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Adhikari NP, Adhikari S, Rijal KR. Community composition and co-occurrence of free-living and particle-attached bacteria in the source region of the Ganges and Brahmaputra Rivers. Int Microbiol 2024:10.1007/s10123-024-00607-6. [PMID: 39400629 DOI: 10.1007/s10123-024-00607-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2024] [Revised: 10/06/2024] [Accepted: 10/08/2024] [Indexed: 10/15/2024]
Abstract
Bacteria have two trophic lifestyles in aquatic ecosystems, i.e., free-living (FL) and particle-attached (PA), with different but essential ecological roles. However, relevant knowledge is still dearth in the upstream source region of the Himalayan Rivers. Thus, we emphasized a comparative study on community composition, co-occurrence, and geographic distribution of the FL and PA bacteria and the effect of environmental factors in the source region of the Ganges and Brahmaputra Rivers. PA bacteria relative to FL harbored a significantly higher local diversity, richness, and evenness. A significantly higher abundance of Betaproteobacteria, Verrucomicrobiota, and Planctomycetota in PA trophic lifestyle and Gammaproteobacteria and Actinomycetota in FL tropic lifestyle and indicator OTUs belonging to related taxa were observed. The spatial variation of the FL and PA bacterial communities was most significantly impacted by dispersal limitation as a discrete factor. Among the environmental parameters, the total nitrogen (TN) was found to be a significant (P < 0.001) driver of the variation in PA communities. Meanwhile, particulate organic carbon (POC) and TN considerably explained the variation of FL communities. A significant correlation (P < 0.001) of TN with dominant bacterial taxa (Pseudomonadota, Actinomycetota, and Verrucomicrobiota) and FL and PA indicator OTUs associated with these taxa further confirmed nitrogen as the limiting nutrient in the source region of the Ganges and Brahmaputra Rivers. The co-occurrence network topological characteristics showed that the PA network was more stable than the FL network, which was more complicated and unstable. Thus, it can be speculated that FL communities relative to PA are more vulnerable to shifting upon disturbances.
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Affiliation(s)
- Namita Paudel Adhikari
- Center for the Pan-Third Pole Environment, Lanzhou University, Lanzhou, 730000, China
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Subash Adhikari
- Center for the Pan-Third Pole Environment, Lanzhou University, Lanzhou, 730000, China.
- State Key Laboratory of Tibetan Plateau Earth System, Resources and Environment (TPESRE), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Komal Raj Rijal
- Central Department of Microbiology, Tribhuvan University, Kirtipur, 44613, Kathmandu, Nepal
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Benoit T, Sajjad D, Cloutier M, Lapen DR, Craiovan E, Sykes EME, Kumar A, Khan IUH. Acinetobacter calcoaceticus-baumannii complex prevalence, spatial-temporal distribution, and contamination sources in Canadian aquatic environments. Microbiol Spectr 2024; 12:e0150924. [PMID: 39240108 PMCID: PMC11449026 DOI: 10.1128/spectrum.01509-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2024] [Accepted: 07/29/2024] [Indexed: 09/07/2024] Open
Abstract
Acinetobacter calcoaceticus-baumannii (ACB) complex has been identified as a group of emerging opportunistic pathogens that cause nosocomial infections. The current study investigates the prevalence, distribution, and diversity of pathogenic ACB complex in various aquatic systems with different uses. Of the total 157 agricultural, raw drinking water intake, recreational beach, and wastewater treatment plant (WWTP) effluent samples, acinetobacters were isolated, quantified, and confirmed by genus- and ACB complex-specific PCR assays. Of all agricultural surface water samples, A. calcoaceticus (65%) was more frequently detected than A. pittii (14%), A. nosocomialis (9%), and A. baumannii (3%). In WWTP effluent samples, A. baumannii was more prevalent in de-chlorinated (60%) samples compared to both A. pittii and A. nosocomialis (40%). Interestingly, A. nosocomialis (43%), A. calcoaceticus (29%), and A. baumannii (14%) were detected in raw drinking water intake samples, whereas A. pittii (50%) and A. nosocomialis (25%) were detected in beach samples. Although no sampling location-specific differences were recorded, significant (P < 0.05) seasonal differences were observed when agricultural surface water samples collected in spring were compared with the summer and fall. Whereas effluent chlorination significantly impacted the degree of prevalence of Acinetobacter in WWTP effluent samples, overall, the prevalence of ACB complex in all sampling locations and seasons indicates that these water sources, containing human-associated ACB complex, may pose potential health risks as community-acquired opportunistic infections.IMPORTANCEAcinetobacter calcoaceticus-baumannii (ACB) complex is a group of organisms known to cause problematic nosocomial opportunistic infections. A member of the species complex, A. baumannii, is becoming a global threat to infection treatment as strains are increasingly develop resistance to antibiotics. The prevalence and distribution of potentially pathogenic Acinetobacter calcoaceticus-baumannii complex species remain poorly understood, and there is a need to better understand the occurrence of A. baumannii in non-nosocomial environments. Our research details the spatial-temporal distribution of ACB complex species in a regional watershed and highlights the presence of ACB complex in wastewater effluent that is discharged into a river. These findings deepen our understanding of this group of species in non-nosocomial environments and encourage the development of monitoring programs for these species in regional waters.
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Affiliation(s)
- Thomas Benoit
- Ottawa Research and
Development Centre, Agriculture and Agri-Food
Canada, Ontario,
Canada
- Department of
Chemistry and Biomolecular Sciences, University of
Ottawa, Ontario,
Canada
| | - Dania Sajjad
- Ottawa Research and
Development Centre, Agriculture and Agri-Food
Canada, Ontario,
Canada
- Department of
Chemistry and Biomolecular Sciences, University of
Ottawa, Ontario,
Canada
| | - Michel Cloutier
- Ottawa Research and
Development Centre, Agriculture and Agri-Food
Canada, Ontario,
Canada
| | - David R. Lapen
- Ottawa Research and
Development Centre, Agriculture and Agri-Food
Canada, Ontario,
Canada
| | - Emilia Craiovan
- Ottawa Research and
Development Centre, Agriculture and Agri-Food
Canada, Ontario,
Canada
| | - Ellen M. E. Sykes
- Department of
Microbiology, University of Manitoba,
Winnipeg, Manitoba,
Canada
| | - Ayush Kumar
- Department of
Microbiology, University of Manitoba,
Winnipeg, Manitoba,
Canada
| | - Izhar U. H. Khan
- Ottawa Research and
Development Centre, Agriculture and Agri-Food
Canada, Ontario,
Canada
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Oliveira JMS, Ottosen LDM, Kofoed MVW. Continuous biomethanation of flue gas-carbon dioxide using bio-integrated carbon capture and utilization. BIORESOURCE TECHNOLOGY 2024; 399:130506. [PMID: 38423486 DOI: 10.1016/j.biortech.2024.130506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 02/26/2024] [Accepted: 02/26/2024] [Indexed: 03/02/2024]
Abstract
Biomethanation of carbon dioxide (CO2) from flue gas is a potential enabler of the green transition, particularly when integrated with the power-to-gas chain. However, challenges arise in achieving synthetic natural gas quality when utilizing CO2 from diluted carbon sources, and the high costs of CO2 separation using amine-based solutions make large-scale implementation unfeasible. We propose an innovative continuous biomethanation system that integrates carbon capture and CO2 stripping through microbial utilization, eliminating expenses with the stripper. Stable continuous biomethane production (83-92 % methane purity) was achieved from flue gas-CO2 using a biocompatible aqueous n-methyldiethanolamine (MDEA) solution (50 mmol/L) under mesophilic and hydrogen-limiting conditions. MDEA was found to be recalcitrant to biodegradation and could be reused after regeneration. Demonstrating the microbial ability to simultaneously strip and convert the captured CO2 and regenerate MDEA provides a new pathway for valorization of flue gas CO2.
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Affiliation(s)
- Jean M S Oliveira
- Department of Biological and Chemical Engineering, Aarhus University, Gustav Wieds Vej 10C, DK-8000, Denmark
| | - Lars D M Ottosen
- Department of Biological and Chemical Engineering, Aarhus University, Gustav Wieds Vej 10C, DK-8000, Denmark; The Novo Nordisk Foundation CO2 Research Center (CORC), Aarhus University, Gustav Wieds Vej 10C, DK-8000, Denmark
| | - Michael V W Kofoed
- Department of Biological and Chemical Engineering, Aarhus University, Gustav Wieds Vej 10C, DK-8000, Denmark; The Novo Nordisk Foundation CO2 Research Center (CORC), Aarhus University, Gustav Wieds Vej 10C, DK-8000, Denmark.
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Dey J, Mahapatra SR, Singh PK, Prabhuswamimath SC, Misra N, Suar M. Designing of multi-epitope peptide vaccine against Acinetobacter baumannii through combined immunoinformatics and protein interaction-based approaches. Immunol Res 2023; 71:639-662. [PMID: 37022613 PMCID: PMC10078064 DOI: 10.1007/s12026-023-09374-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 03/16/2023] [Indexed: 04/07/2023]
Abstract
Acinetobacter baumannii is one of the major pathogenic ESKAPE bacterium, which is responsible for about more than 722,000 cases in a year, globally. Despite the alarming increase in multidrug resistance, a safe and effective vaccine for Acinetobacter infections is still not available. Hence in the current study, a multiepitope vaccine construct was developed using linear B cell, cytotoxic T cell, and helper T cell epitopes from the antigenic and well-conserved lipopolysaccharide assembly proteins employing systematic immunoinformatics and structural vaccinology strategies. The multi-peptide vaccine was predicted to be highly antigenic, non-allergenic, non-toxic, and cover maximum population coverage worldwide. Further, the vaccine construct was modeled along with adjuvant and peptide linkers and validated to achieve a high-quality three-dimensional structure which was subsequently utilized for cytokine prediction, disulfide engineering, and docking analyses with Toll-like receptor (TLR4). Ramachandran plot showed 98.3% of the residues were located in the most favorable and permitted regions, thereby corroborating the feasibility of the modeled vaccine construct. Molecular dynamics simulation for a 100 ns timeframe further confirmed the stability of the binding vaccine-receptor complex. Finally, in silico cloning and codon adaptation were also performed with the pET28a (+) plasmid vector to determine the efficiency of expression and translation of the vaccine. Immune simulation studies demonstrated that the vaccine could trigger both B and T cell responses and can elicit strong primary, secondary, and tertiary immune responses. The designed multi-peptide subunit vaccine would certainly expedite the experimental approach for the development of a vaccine against A. baumannii infection.
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Affiliation(s)
- Jyotirmayee Dey
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be University, -751024, Bhubaneswar, India
| | - Soumya Ranjan Mahapatra
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be University, -751024, Bhubaneswar, India
| | | | - Samudyata C Prabhuswamimath
- Department of Biotechnology and Bioinformatics, School of Life Sciences, JSS Academy of Higher Education and Research, -570015, Mysuru, Karnataka, India
| | - Namrata Misra
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be University, -751024, Bhubaneswar, India.
- KIIT-Technology Business Incubator (KIIT-TBI), Kalinga Institute of Industrial Technology (KIIT), Deemed to be University, -751024, Bhubaneswar, India.
| | - Mrutyunjay Suar
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be University, -751024, Bhubaneswar, India.
- KIIT-Technology Business Incubator (KIIT-TBI), Kalinga Institute of Industrial Technology (KIIT), Deemed to be University, -751024, Bhubaneswar, India.
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Boulesnam SL, Hamaidi-Chergui F, Benamara M, Azrou S. Phenotypical Comparison between Environmental and Clinical Acinetobacter baumannii Strains Isolated from an Intensive Care Unit. Malays J Med Sci 2023; 30:85-93. [PMID: 37655144 PMCID: PMC10467598 DOI: 10.21315/mjms2023.30.4.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 12/05/2022] [Indexed: 09/02/2023] Open
Abstract
Background Acinetobacter baumannii (A. baumannii) causes a variety of nosocomial infections that mainly affect critically ill patients in intensive care units (ICUs). The objective of this study was to assess the prevalence of A. baumannii in the ICU environment and evaluate the antibiotic resistance and biofilm formation ability of the environmental isolates compared to those isolated from ICU patients simultaneously. Methods A total of 166 non-duplicate ICU samples (80 environmental and 86 clinical) were collected between January 2019 and January 2020. Antimicrobial susceptibility detection was determined using the disc diffusion method, and the strains were evaluated for the minimum inhibitory concentration (MIC) of imipenem (IMP) using broth microdilution or metallo-β-lactamase (MBL) detection according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. The isolates' capacity to produce biofilms was evaluated using the tube method and the crystal violet microtitre plate-based method. Results A. baumannii was identified in 25 (31.25%) environmental and 30 (34.88%) clinical samples, and beds were the most infected (60%). Both types of isolate demonstrated a rate surpassing 80% resistance to the tested antibiotics. Phenotypically, the environmental and clinical strains were found to be MBL producers. Fourteen environmental (56%) and 15 clinical (50%) strains were found to be moderate biofilm producers, indicating that each isolate has a high biofilm-forming capacity. Conclusion These results show that the spread of multidrug-resistant (MDR) A. baumannii in an ICU setting emphasises the necessity of disinfecting and cleaning medical devices and surfaces to prevent and restrict cross-transmission. Intensive surveillance and infection control methods are also of paramount importance.
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Affiliation(s)
- Saliha Lydia Boulesnam
- Biotechnology, Environment and Health Laboratory, Biology Department, Blida 1 University, Algeria
| | - Fella Hamaidi-Chergui
- Biotechnology, Environment and Health Laboratory, Biology Department, Blida 1 University, Algeria
| | | | - Sihem Azrou
- Microbiology Laboratory, Faculty of Pharmacy of Algiers, Algeria
- Central Laboratory, Beni Messous EPH, Algeria
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Gagnon JC, Beauregard-Tousignant S, Marcil JS, Lazar CS. Deep Isolated Aquifer Brines Harbor Atypical Halophilic Microbial Communities in Quebec, Canada. Genes (Basel) 2023; 14:1529. [PMID: 37628582 PMCID: PMC10454208 DOI: 10.3390/genes14081529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/21/2023] [Accepted: 07/24/2023] [Indexed: 08/27/2023] Open
Abstract
The deep terrestrial subsurface, hundreds of meters to kilometers below the surface, is characterized by oligotrophic conditions, dark and often anoxic settings, with fluctuating pH, salinity, and water availability. Despite this, microbial populations are detected and active, contributing to biogeochemical cycles over geological time. Because it is extremely difficult to access the deep biosphere, little is known about the identity and metabolisms of these communities, although they likely possess unknown pathways and might interfere with deep waste deposits. Therefore, we analyzed rock and groundwater microbial communities from deep, isolated brine aquifers in two regions dating back to the Ordovician and Devonian, using amplicon and whole genome sequencing. We observed significant differences in diversity and community structure between both regions, suggesting an impact of site age and composition. The deep hypersaline groundwater did not contain typical halophilic bacteria, and genomes suggested pathways involved in protein and hydrocarbon degradation, and carbon fixation. We identified mainly one strategy to cope with osmotic stress: compatible solute uptake and biosynthesis. Finally, we detected many bacteriophage families, potentially indicating that bacteria are infected. However, we also found auxiliary metabolic genes in the viral genomes, probably conferring an advantage to the infected hosts.
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Affiliation(s)
- Jean-Christophe Gagnon
- Department of Biological Sciences, University of Québec at Montréal (UQAM), C.P. 8888, Succ. Centre-Ville, Montréal, QC H3C 3P8, Canada; (J.-C.G.); (S.B.-T.)
- Interuniversity Research Group in Limnology/Groupe de Recherche Interuniversitaire en Limnologie (GRIL), Montréal, QC H3C 3P8, Canada
| | - Samuel Beauregard-Tousignant
- Department of Biological Sciences, University of Québec at Montréal (UQAM), C.P. 8888, Succ. Centre-Ville, Montréal, QC H3C 3P8, Canada; (J.-C.G.); (S.B.-T.)
| | - Jean-Sébastien Marcil
- Derena Geosciences, Quebec, QC G7A 3Y5, Canada;
- Ressources Utica Inc., Quebec, QC G1V 4M7, Canada
| | - Cassandre Sara Lazar
- Department of Biological Sciences, University of Québec at Montréal (UQAM), C.P. 8888, Succ. Centre-Ville, Montréal, QC H3C 3P8, Canada; (J.-C.G.); (S.B.-T.)
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7
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Ren X, Palmer LD. Acinetobacter Metabolism in Infection and Antimicrobial Resistance. Infect Immun 2023:e0043322. [PMID: 37191522 DOI: 10.1128/iai.00433-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
Acinetobacter infections have high rates of mortality due to an increasing incidence of infections by multidrug-resistant (MDR) and extensively-drug-resistant (XDR) strains. Therefore, new therapeutic strategies for the treatment of Acinetobacter infections are urgently needed. Acinetobacter spp. are Gram-negative coccobacilli that are obligate aerobes and can utilize a wide variety of carbon sources. Acinetobacter baumannii is the main cause of Acinetobacter infections, and recent work has identified multiple strategies A. baumannii uses to acquire nutrients and replicate in the face of host nutrient restriction. Some host nutrient sources also serve antimicrobial and immunomodulatory functions. Hence, understanding Acinetobacter metabolism during infection may provide new insights into novel infection control measures. In this review, we focus on the role of metabolism during infection and in resistance to antibiotics and other antimicrobial agents and discuss the possibility that metabolism may be exploited to identify novel targets to treat Acinetobacter infections.
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Affiliation(s)
- Xiaomei Ren
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
| | - Lauren D Palmer
- Department of Microbiology and Immunology, University of Illinois Chicago, Chicago, Illinois, USA
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Nezhad NG, Rahman RNZRA, Normi YM, Oslan SN, Shariff FM, Leow TC. Isolation, screening and molecular characterization of phytase-producing microorganisms to discover the novel phytase. Biologia (Bratisl) 2023; 78:2527-2537. [DOI: 10.1007/s11756-023-01391-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 03/10/2023] [Indexed: 09/02/2023]
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Goodarzi Z, Asad S, Mehrshad M. Genome-resolved insight into the reservoir of antibiotic resistance genes in aquatic microbial community. Sci Rep 2022; 12:21047. [PMID: 36473884 PMCID: PMC9726936 DOI: 10.1038/s41598-022-25026-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 11/23/2022] [Indexed: 12/12/2022] Open
Abstract
Aquatic microbial communities are an important reservoir of antibiotic resistance genes (ARGs). However, distribution and diversity of different ARG categories in environmental microbes with different ecological strategies is not yet well studied. Despite the potential exposure of the southern part of the Caspian Sea to the release of antibiotics, little is known about its natural resistome profile. We used a combination of Hidden Markov model (HMM), homology alignment and a deep learning approach for comprehensive screening of the diversity and distribution of ARGs in the Caspian Sea metagenomes at genome resolution. Detected ARGs were classified into five antibiotic resistance categories including prevention of access to target (44%), modification/protection of targets (30%), direct modification of antibiotics (22%), stress resistance (3%), and metal resistance (1%). The 102 detected ARG containing metagenome-assembled genomes of the Caspian Sea were dominated by representatives of Acidimicrobiia, Gammaproteobacteria, and Actinobacteria classes. Comparative analysis revealed that the highly abundant, oligotrophic, and genome streamlined representatives of taxa Acidimicrobiia and Actinobacteria modify the antibiotic target via mutation to develop antibiotic resistance rather than carrying extra resistance genes. Our results help with understanding how the encoded resistance categories of each genome are aligned with its ecological strategies.
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Affiliation(s)
- Zahra Goodarzi
- grid.46072.370000 0004 0612 7950Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran
| | - Sedigheh Asad
- grid.46072.370000 0004 0612 7950Department of Biotechnology, College of Science, University of Tehran, Tehran, Iran
| | - Maliheh Mehrshad
- grid.6341.00000 0000 8578 2742Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences (SLU), Box 7050, 75007 Uppsala, Sweden
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Potentiate the activity of current antibiotics by naringin dihydrochalcone targeting the AdeABC efflux pump of multidrug-resistant Acinetobacter baumannii. Int J Biol Macromol 2022; 217:592-605. [PMID: 35841965 DOI: 10.1016/j.ijbiomac.2022.07.065] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 11/23/2022]
Abstract
Acinetobacter baumannii is an ESKAPE pathogen responsible for severe nosocomial infections. Among all the mechanisms contributing to multidrug resistance, efflux pumps have gained significant attention due to their widespread distribution among bacterial species and broad substrate specificity. This study has investigated the diverse roles of efflux pumps present in carbapenem-resistant A. baumannii (CRAB) and screen an efflux pump inhibitor. The result showed the presence of AdeABC, AdeFGH, AdeIJK, and AbeM efflux pumps in CRAB, and experimental studies using gene mutants demonstrated the significant role of AdeABC in carbapenem resistance, biofilm formation, surface motility, pathogenesis, bacterial adherence, and invasion to the host cells. The structure-based ligand screening, molecular mechanics, molecular dynamics simulation, and experimental validation using efflux pump mutants and antibiotic accumulation assay identified naringin dihydrochalcone (NDC) as the lead against AdeB. This lead was selected as a capping agent for silver nanoparticles. The NDC-capped silver nanoparticles (NDC-AgNPs) were characterized by UV-spectroscopy, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and scanning electron microscopy (SEM). The investigated molecular mechanism showed that the NDC-AgNPs possessed multiple mechanisms of action. In addition to efflux inhibitory activity, it also generates reactive oxygen and nitrogen species as well as causes change in the electrochemical gradient in CRAB. The proton gradient is important for the function of AdeABC; hence altering the electrochemical gradient also disrupts its efflux activity. Moreover, A. baumannii did not develop any resistance against NDC-AgNPs till several generations which were investigated. The NDC-AgNPs were also found to be effective against carbapenem-resistant clinical isolates of A. baumannii. Therefore, the present study provided an insight into the efflux pump mediated carbapenem resistance and possible inhibitor NDC-AgNPs to combat AdeABC efflux pump mediated resistance.
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Abdelhafiz Y, Fernandes JMO, Stefani E, Albanese D, Donati C, Kiron V. Power Play of Commensal Bacteria in the Buccal Cavity of Female Nile Tilapia. Front Microbiol 2021; 12:773351. [PMID: 34867911 PMCID: PMC8636895 DOI: 10.3389/fmicb.2021.773351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/14/2021] [Indexed: 01/29/2023] Open
Abstract
Fish are widely exposed to higher microbial loads compared to land and air animals. It is known that the microbiome plays an essential role in the health and development of the host. The oral microbiome is vital in females of different organisms, including the maternal mouthbrooding species such as Nile tilapia (Oreochromis niloticus). The present study reports for the first time the microbial composition in the buccal cavity of female and male Nile tilapia reared in a recirculating aquaculture system. Mucus samples were collected from the buccal cavity of 58 adult fish (∼1 kg), and 16S rRNA gene amplicon sequencing was used to profile the microbial communities in females and males. The analysis revealed that opportunistic pathogens such as Streptococcus sp. were less abundant in the female buccal cavity. The power play of certain bacteria such as Acinetobacter, Acidobacteria (GP4 and GP6), and Saccharibacteria that have known metabolic advantages was evident in females compared to males. Association networks inferred from relative abundances showed few microbe–microbe interactions of opportunistic pathogens in female fish. The findings of opportunistic bacteria and their interactions with other microbes will be valuable for improving Nile tilapia rearing practices. The presence of bacteria with specific functions in the buccal cavity of female fish points to their ability to create a protective microbial ecosystem for the offspring.
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Affiliation(s)
- Yousri Abdelhafiz
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | | | - Erika Stefani
- Unit of Computational Biology, Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy
| | - Davide Albanese
- Unit of Computational Biology, Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy
| | - Claudio Donati
- Unit of Computational Biology, Research and Innovation Centre, Fondazione Edmund Mach, San Michele all'Adige, Italy
| | - Viswanath Kiron
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
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CsrA Coordinates Compatible Solute Synthesis in Acinetobacter baumannii and Facilitates Growth in Human Urine. Microbiol Spectr 2021; 9:e0129621. [PMID: 34730379 PMCID: PMC8567240 DOI: 10.1128/spectrum.01296-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
CsrA is a global regulator widespread in bacteria and known to be involved in different physiological processes, including pathogenicity. Deletion of csrA of Acinetobacter baumannii strain ATCC 19606 resulted in a mutant that was unable to utilize a broad range of carbon and energy sources, including amino acids. This defect in amino acid metabolism was most likely responsible for the growth inhibition of the ΔcsrA mutant in human urine, where amino acids are the most abundant carbon source for A. baumannii. Recent studies revealed that deletion of csrA in the A. baumannii strains AB09-003 and ATCC 17961 resulted in an increase in hyperosmotic stress resistance. However, the molecular basis for this observation remained unknown. This study aimed to investigate the role of CsrA in compatible solute synthesis. We observed striking differences in the ability of different A. baumannii strains to cope with hyperosmotic stress. Strains AB09-003 and ATCC 17961 were strongly impaired in hyperosmotic stress resistance in comparison to strain ATCC 19606. These differences were abolished by deletion of csrA and are in line with the ability to synthesize compatible solutes. In the salt-sensitive strains AB09-003 and ATCC 17961, compatible solute synthesis was repressed by CsrA. This impairment is mediated via CsrA and could be overcome by deletion of csrA from the genome. IMPORTANCE The opportunistic human pathogen Acinetobacter baumannii has become one of the leading causes of nosocomial infections around the world due to the increasing prevalence of multidrug-resistant strains and their optimal adaptation to clinical environments and the human host. Recently, it was found that CsrA, a global mRNA binding posttranscriptional regulator, plays a role in osmotic stress adaptation, virulence, and growth on amino acids of A. baumannii AB09-003 and ATCC 17961. Here, we report that this is also the case for A. baumannii ATCC 19606. However, we observed significant differences in the ΔcsrA mutants with respect to osmostress resistance, such as the AB09-003 and 17961 mutants being enhanced in osmostress resistance whereas the ATCC 19606 mutant was not. This suggests that the role of CsrA in osmotic stress adaptation is strain specific. Furthermore, we provide clear evidence that CsrA is essential for growth in human urine and at high temperatures.
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Lombardo D, Cordovana M, Deidda F, Pane M, Ambretti S. Application of Fourier transform infrared spectroscopy for real-time typing of Acinetobacter baumannii outbreak in intensive care unit. Future Microbiol 2021; 16:1239-1250. [PMID: 34674538 DOI: 10.2217/fmb-2020-0276] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: Acinetobacter baumannii is a pathogen of serious concern, often exhibiting multiple antibiotic resistance, frequently associated with hospital outbreaks in intensive care units. A prompt detection and tracking of these isolates is crucial. Reference methods for typing (pulsed-field gel electrophoresis, whole-genome sequencing) are accurate, but expensive and time-consuming, therefore limited to retrospective analysis. Materials & methods: In this study, the application of the FTIR-based IR Biotyper® (IRBT) to track and monitor in real-time the spread of a multidrug-resistant A. baumannii outbreak was investigated. The index case and the multidrug-resistant A. baumannii isolates collected in the following 3 weeks were investigated. Results: IR Biotyper® clustering results were fully confirmed by pulsed-field gel electrophoresis results. Conclusions: IR Biotyper represent a promising tool for real-time hospital hygiene, enabling a prompt and reliable typing.
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Affiliation(s)
- Donatella Lombardo
- Operative Unit of Microbiology, University Hospital Policlinico Sant'Orsola-Malpighi, Bologna, Italy
| | - Miriam Cordovana
- Operative Unit of Microbiology, University Hospital Policlinico Sant'Orsola-Malpighi, Bologna, Italy
| | | | - Marco Pane
- Probiotical Research s.r.l., Novara, Italy
| | - Simone Ambretti
- Operative Unit of Microbiology, University Hospital Policlinico Sant'Orsola-Malpighi, Bologna, Italy
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14
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Baumas CMJ, Le Moigne FAC, Garel M, Bhairy N, Guasco S, Riou V, Armougom F, Grossart HP, Tamburini C. Mesopelagic microbial carbon production correlates with diversity across different marine particle fractions. THE ISME JOURNAL 2021; 15:1695-1708. [PMID: 33452475 PMCID: PMC8163737 DOI: 10.1038/s41396-020-00880-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 12/02/2020] [Accepted: 12/09/2020] [Indexed: 01/29/2023]
Abstract
The vertical flux of marine snow particles significantly reduces atmospheric carbon dioxide concentration. In the mesopelagic zone, a large proportion of the organic carbon carried by sinking particles dissipates thereby escaping long term sequestration. Particle associated prokaryotes are largely responsible for such organic carbon loss. However, links between this important ecosystem flux and ecological processes such as community development of prokaryotes on different particle fractions (sinking vs. non-sinking) are yet virtually unknown. This prevents accurate predictions of mesopelagic organic carbon loss in response to changing ocean dynamics. Using combined measurements of prokaryotic heterotrophic production rates and species richness in the North Atlantic, we reveal that carbon loss rates and associated microbial richness are drastically different with particle fractions. Our results demonstrate a strong negative correlation between prokaryotic carbon losses and species richness. Such a trend may be related to prokaryotes detaching from fast-sinking particles constantly enriching non-sinking associated communities in the mesopelagic zone. Existing global scale data suggest this negative correlation is a widespread feature of mesopelagic microbes.
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Affiliation(s)
- Chloé M. J. Baumas
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
| | - Frédéric A. C. Le Moigne
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
| | - Marc Garel
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
| | - Nagib Bhairy
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
| | - Sophie Guasco
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
| | - Virginie Riou
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
| | - Fabrice Armougom
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
| | - Hans-Peter Grossart
- grid.419247.d0000 0001 2108 8097Department of Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany ,grid.11348.3f0000 0001 0942 1117Institute of Biochemistry and Biology, Postdam University, 14469 Potsdam, Germany
| | - Christian Tamburini
- grid.500499.10000 0004 1758 6271Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France
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15
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Precise Species Identification for Acinetobacter: a Genome-Based Study with Description of Two Novel Acinetobacter Species. mSystems 2021; 6:e0023721. [PMID: 34061620 PMCID: PMC8269215 DOI: 10.1128/msystems.00237-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The genus Acinetobacter comprises species with ecological significance and opportunistic pathogens and has a complicated taxonomy. Precise species identification is a foundation for understanding bacteria. In this study, we found and characterized two novel Acinetobacter species, namely, Acinetobacter tianfuensis sp. nov. and Acinetobacter rongchengensis sp. nov., based on phenotype examinations and genome analyses of the two strains WCHAc060012T and WCHAc060115T. The two strains had ≤89.69% (mean, 79.28% or 79.72%) average nucleotide identity (ANI) and ≤36.4% (mean, 20.89% or 22.19%) in silico DNA-DNA hybridization (isDDH) values compared with each other and all known Acinetobacter species. Both species can be differentiated from all hitherto known Acinetobacter species by a combination of phenotypic characteristics. We found that Acinetobacter pullorum B301T and Acinetobacter portensis AC 877T are actually the same species with 98.59% ANI and 90.4% isDDH values. We then applied the updated taxonomy to curate 3,956 Acinetobacter genomes in GenBank and found that 6% of Acinetobacter genomes (n = 234) are required to be corrected or updated. We identified 56 novel tentative Acinetobacter species, extending the number of Acinetobacter species to 144, including 68 with species names and 76 unnamed taxa. We also found that ANI and the average amino acid identity (AAI) values among type or reference strains of all Acinetobacter species and taxa are ≥76.97% and ≥66.5%, respectively, which are higher than the proposed cutoffs to define the genus boundary. This study highlights the complex taxonomy of Acinetobacter as a single genus and the paramount importance of precise species identification. The newly identified unnamed taxa warrant further studies. IMPORTANCEAcinetobacter species are widely distributed in nature and are of important ecological significance and clinical relevance. In this study, first, we significantly update the taxonomy of Acinetobacter by reporting two novel Acinetobacter species, namely, Acinetobacter tianfuensis and Acinetobacter rongchengensis, and by identifying Acinetobacter portensis as a synonym of Acinetobacter pullorum. Second, we curated Acinetobacter genome sequences deposited in GenBank (n = 3,956) using the updated taxonomy by correcting species assignations for 6% (n = 234) genomes and by assigning 94 (2.4%) to 56 previously unknown tentative species (taxa). Therefore, after curation, we further update the genus Acinetobacter to comprise 144 species, including 68 with species names and 76 unnamed taxa. Third, we addressed the question of whether such a large number of species should be divided in different genera and found that Acinetobacter is indeed a single genus. Our study significantly advanced the taxonomy of Acinetobacter, an important genus with science and health implications.
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Nemec A, Radolfová-Křížová L, Maixnerová M, Nemec M, Španělová P, Šafránková R, Šedo O, Lopes BS, Higgins PG. Delineation of a novel environmental phylogroup of the genus Acinetobacter encompassing Acinetobacter terrae sp. nov., Acinetobacter terrestris sp. nov. and three other tentative species. Syst Appl Microbiol 2021; 44:126217. [PMID: 34107439 DOI: 10.1016/j.syapm.2021.126217] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/14/2021] [Accepted: 05/14/2021] [Indexed: 11/29/2022]
Abstract
This study aimed to define the taxonomic position and structure of a novel, taxonomically unique group of 26 Acinetobacter strains, provisionally designated Taxon 24 (T24). The strains were recovered from soil and freshwater ecosystems (n = 21) or animals (n = 5) in Czechia, Scotland, Germany, the Netherlands and Turkey between 1993 and 2015. They were non-glucose-acidifying, nonhemolytic, nonproteolytic, growing at 32 °C and on acetate and ethanol as single carbon sources, but not on 4-hydroxybenzoate and mostly not at 37 °C. Their whole-genome sequences were 3.0-3.7 Mb in size, with GC contents of 39.8-41.3%. Based on core genome phylogenetic analysis, the 26 strains formed a distinct clade within the genus Acinetobacter, with strongly supported subclades termed T24A (n = 11), T24B (n = 8), T24C (n = 2), T24D (n = 3) and T24E (n = 2). The internal genomic ANIb values for these subclades were >94.8%, while the ANIb values between them were <92.5%. The results of MALDI-TOF MS-based analyses agreed with this classification. The five subclades differed from each other in the results of one to six carbon source assimilation tests. Given the genomic and phenotypic distinctness, internal coherence, numbers of available strains and geographically diverse origin of T24A and T24B, we propose the names Acinetobacter terrae sp. nov. and Acinetobacter terrestris sp. nov. for these two taxa, respectively. The type strains are ANC 4282v (= CCM 8986T = CCUG 73811T = CNCTC 8082T) and ANC 4471T (= CCM 8985T = CCUG 73812T = CNCTC 8093T), respectively. We conclude that these two species together with the other T24 strains represent a widely dispersed Acinetobacter clade primarily associated with terrestrial ecosystems.
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Affiliation(s)
- Alexandr Nemec
- Laboratory of Bacterial Genetics, Centre for Epidemiology and Microbiology, National Institute of Public Health, Šrobárova 48, 100 42 Prague 10, Czech Republic; Department of Medical Microbiology, Second Faculty of Medicine, Charles University, V Úvalu 84, 150 06 Prague 5, Czech Republic.
| | - Lenka Radolfová-Křížová
- Laboratory of Bacterial Genetics, Centre for Epidemiology and Microbiology, National Institute of Public Health, Šrobárova 48, 100 42 Prague 10, Czech Republic
| | - Martina Maixnerová
- Laboratory of Bacterial Genetics, Centre for Epidemiology and Microbiology, National Institute of Public Health, Šrobárova 48, 100 42 Prague 10, Czech Republic
| | - Matěj Nemec
- Laboratory of Bacterial Genetics, Centre for Epidemiology and Microbiology, National Institute of Public Health, Šrobárova 48, 100 42 Prague 10, Czech Republic
| | - Petra Španělová
- Czech National Collection of Type Cultures, Centre for Epidemiology and Microbiology, National Institute of Public Health, Šrobárova 48, 100 42 Prague 10, Czech Republic
| | - Renata Šafránková
- Czech National Collection of Type Cultures, Centre for Epidemiology and Microbiology, National Institute of Public Health, Šrobárova 48, 100 42 Prague 10, Czech Republic
| | - Ondrej Šedo
- Research Group Proteomics, Central European Institute of Technology and National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic
| | - Bruno S Lopes
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Aberdeen AB25 2ZD, UK
| | - Paul G Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelstrasse 19-21 50935 Cologne, and German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
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17
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Recombinant Production and Characterization of an Extracellular Subtilisin-Like Serine Protease from Acinetobacter baumannii of Fermented Food Origin. Protein J 2021; 40:419-435. [PMID: 33870461 PMCID: PMC8053418 DOI: 10.1007/s10930-021-09986-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2021] [Indexed: 12/20/2022]
Abstract
Acinetobacter baumannii is a ubiquitous bacteria that is increasingly becoming a formidable nosocomial pathogen. Due to its clinical relevance, studies on the bacteria's secretory molecules especially extracellular proteases are of interest primarily in relation to the enzyme's role in virulence. Besides, favorable properties that extracellular proteases possess may be exploited for commercial use thus there is a need to investigate extracellular proteases from Acinetobacter baumannii to gain insights into their catalytic properties. In this study, an extracellular subtilisin-like serine protease from Acinetobacter baumannii designated as SPSFQ that was isolated from fermented food was recombinantly expressed and characterized. The mature catalytically active form of SPSFQ shared a high percentage sequence identity of 99% to extracellular proteases from clinical isolates of Acinetobacter baumannii and Klebsiella pneumoniae as well as a moderately high percentage identity to other bacterial proteases with known keratinolytic and collagenolytic activity. The homology model of mature SPSFQ revealed its structure is composed of 10 β-strands, 8 α-helices, and connecting loops resembling a typical architecture of subtilisin-like α/β motif. SPSFQ is catalytically active at an optimum temperature of 40 °C and pH 9. Its activity is stimulated in the presence of Ca2+ and severely inhibited in the presence of PMSF. SPSFQ also displayed the ability to degrade several tissue-associated protein substrates such as keratin, collagen, and fibrin. Accordingly, our study shed light on the catalytic properties of a previously uncharacterized extracellular serine protease from Acinetobacter baumannii that warrants further investigations into its potential role as a virulence factor in pathogenicity and commercial applications.
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18
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Lavefve L, Cureau N, Rodhouse L, Marasini D, Walker LM, Ashley D, Lee S, Gadonna‐Widehem P, Anton PM, Carbonero F. Microbiota profiles and dynamics in fermented plant‐based products and preliminary assessment of their in vitro gut microbiota modulation. FOOD FRONTIERS 2021. [DOI: 10.1002/fft2.75] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Laura Lavefve
- Department of Food Science University of Arkansas Fayetteville AR USA
| | - Natacha Cureau
- Department of Food Science University of Arkansas Fayetteville AR USA
| | - Lindsey Rodhouse
- Department of Food Science University of Arkansas Fayetteville AR USA
| | - Daya Marasini
- Department of Food Science University of Arkansas Fayetteville AR USA
| | - Laura M. Walker
- Department of Biology Washington University in Saint‐Louis St Louis MO USA
| | - Danielle Ashley
- Department of Food Science University of Arkansas Fayetteville AR USA
| | - Sun‐Ok Lee
- Department of Food Science University of Arkansas Fayetteville AR USA
| | - Pascale Gadonna‐Widehem
- Transformations & Agroresources, ULR7519 Institut Polytechnique UniLaSalle, Universite d’Artois Beauvais France
| | - Pauline M. Anton
- Transformations & Agroresources, ULR7519 Institut Polytechnique UniLaSalle, Universite d’Artois Beauvais France
| | - Franck Carbonero
- Department of Food Science University of Arkansas Fayetteville AR USA
- Department of Nutrition and Exercise Physiology Elson Floyd School of Medicine Washington State University‐Spokane Spokane WA USA
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19
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Blaschke U, Skiebe E, Wilharm G. Novel Genes Required for Surface-Associated Motility in Acinetobacter baumannii. Curr Microbiol 2021; 78:1509-1528. [PMID: 33666749 PMCID: PMC7997844 DOI: 10.1007/s00284-021-02407-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 02/10/2021] [Indexed: 01/28/2023]
Abstract
Acinetobacter baumannii is an opportunistic and increasingly multi-drug resistant human pathogen rated as a critical priority one pathogen for the development of new antibiotics by the WHO in 2017. Despite the lack of flagella, A. baumannii can move along wet surfaces in two different ways: via twitching motility and surface-associated motility. While twitching motility is known to depend on type IV pili, the mechanism of surface-associated motility is poorly understood. In this study, we established a library of 30 A. baumannii ATCC® 17978™ mutants that displayed deficiency in surface-associated motility. By making use of natural competence, we also introduced these mutations into strain 29D2 to differentiate strain-specific versus species-specific effects of mutations. Mutated genes were associated with purine/pyrimidine/folate biosynthesis (e.g. purH, purF, purM, purE), alarmone/stress metabolism (e.g. Ap4A hydrolase), RNA modification/regulation (e.g. methionyl-tRNA synthetase), outer membrane proteins (e.g. ompA), and genes involved in natural competence (comEC). All tested mutants originally identified as motility-deficient in strain ATCC® 17978™ also displayed a motility-deficient phenotype in 29D2. By contrast, further comparative characterization of the mutant sets of both strains regarding pellicle biofilm formation, antibiotic resistance, and virulence in the Galleria mellonella infection model revealed numerous strain-specific mutant phenotypes. Our studies highlight the need for comparative analyses to characterize gene functions in A. baumannii and for further studies on the mechanisms underlying surface-associated motility.
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Affiliation(s)
- Ulrike Blaschke
- Robert Koch Institute, Project group P2, Burgstr. 37, 38855, Wernigerode, Germany.
| | - Evelyn Skiebe
- Robert Koch Institute, Project group P2, Burgstr. 37, 38855, Wernigerode, Germany
| | - Gottfried Wilharm
- Robert Koch Institute, Project group P2, Burgstr. 37, 38855, Wernigerode, Germany.
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20
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Kazou M, Grafakou A, Tsakalidou E, Georgalaki M. Zooming Into the Microbiota of Home-Made and Industrial Kefir Produced in Greece Using Classical Microbiological and Amplicon-Based Metagenomics Analyses. Front Microbiol 2021; 12:621069. [PMID: 33584624 PMCID: PMC7876260 DOI: 10.3389/fmicb.2021.621069] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 01/07/2021] [Indexed: 11/22/2022] Open
Abstract
Kefir is a high nutritional fermented dairy beverage associated with a wide range of health benefits. It constitutes a unique symbiotic association, comprising mainly lactic acid bacteria, yeasts, and occasionally acetic acid bacteria, which is strongly influenced by the geographical origin of the grains, the type of milk used, and the manufacture technology applied. Until recently, kefir microbiota has been almost exclusively studied by culture-dependent techniques. However, high-throughput sequencing, alongside omics approaches, has revolutionized the study of food microbial communities. In the present study, the bacterial, and yeast/fungal microbiota of four home-made samples (both grains and drinks), deriving from well spread geographical regions of Greece, and four industrial beverages, was elucidated by culture-dependent and -independent analyses. In all samples, classical microbiological analysis revealed varying populations of LAB and yeasts, ranging from 5.32 to 9.60 log CFU mL–1 or g–1, and 2.49 to 7.80 log CFU mL–1 or g–1, respectively, while in two industrial samples no yeasts were detected. Listeria monocytogenes, Salmonella spp. and Staphylococcus spp. were absent from all the samples analyzed, whereas Enterobacteriaceae were detected in one of them. From a total of 123 isolates, including 91 bacteria and 32 yeasts, Lentilactobacillus kefiri, Leuconostoc mesenteroides, and Lactococcus lactis as well as Kluvyeromyces marxianus and Saccharomyces cerevisiae were the mostly identified bacterial and yeast species, respectively, in the home-made samples. On the contrary, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Lacticaseibacillus rhamnosus along with Debaryomyces hansenii and K. marxianus were the main bacterial and yeast species, respectively, isolated from the industrial beverages. In agreement with the identification results obtained from the culture-dependent approaches, amplicon-based metagenomics analysis revealed that the most abundant bacterial genera in almost all home-made samples (both grains and drinks) were Lactobacillus and Lactococcus, while Saccharomyces, Kazachstania, and Kluvyeromyces were the predominant yeasts/fungi. On the other hand, Streptococcus, Lactobacillus, and Lactococcus as well as Kluvyeromyces and Debaryomyces dominated the bacterial and yeast/fungal microbiota, respectively, in the industrial beverages. This is the first report on the microbiota of kefir produced in Greece by a holistic approach combining classical microbiological, molecular, and amplicon-based metagenomics analyses.
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Affiliation(s)
- Maria Kazou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Andriana Grafakou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Effie Tsakalidou
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Marina Georgalaki
- Laboratory of Dairy Research, Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
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21
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Deems A, Du Prey M, Dowd SE, McLaughlin RW. Characterization of the Biodiesel Degrading Acinetobacter oleivorans Strain PT8 Isolated from the Fecal Material of a Painted Turtle (Chrysemys picta). Curr Microbiol 2021; 78:522-527. [PMID: 33392672 DOI: 10.1007/s00284-020-02320-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 12/07/2020] [Indexed: 11/26/2022]
Abstract
Acinetobacter species are gram-negative, non-fermenting bacteria with coccobacilli morphology. The bacteria are found ubiquitously and have the ability to occupy niches which include environmental sites, animals, and humans. The original purpose of this study was to determine if painted turtles (Chrysemys picta) living in the wild in Western Wisconsin were colonized with carbapenem-resistant bacteria. Fecal samples from ten turtles were examined for carbapenem-resistant bacteria. None of the isolates were found to be carbapenem resistant by antimicrobial susceptibility testing. However, all the isolates were resistant to other β-lactams and chloramphenicol classes of antimicrobials. One isolate, Acinetobacter oleivorans strain PT8, was selected for additional characterization, including whole-genome sequencing (WGS). Strain PT8 is capable of degrading biodiesel, forming biofilms, and has a putative type 6 gene cluster. Finally, the taxonomic position of the available whole-genome sequences of 25 A. oleivorans genomes from purified isolates was determined.
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Affiliation(s)
- Amanda Deems
- General Studies, Gateway Technical College, 3520-30th Avenue, Kenosha, WI, 53144, USA
| | - Michael Du Prey
- General Studies, Gateway Technical College, 3520-30th Avenue, Kenosha, WI, 53144, USA
| | - Scot E Dowd
- MR DNA (Molecular Research LP), Shallowater, TX, USA
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22
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Gallagher P, Baker S. Developing new therapeutic approaches for treating infections caused by multi-drug resistant Acinetobacter baumannii. J Infect 2020; 81:857-861. [DOI: 10.1016/j.jinf.2020.10.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 10/21/2020] [Indexed: 12/23/2022]
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23
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Benoit T, Cloutier M, Schop R, Lowerison MW, Khan IUH. Comparative assessment of growth media and incubation conditions for enhanced recovery and isolation of Acinetobacter baumannii from aquatic matrices. J Microbiol Methods 2020; 176:106023. [PMID: 32795636 DOI: 10.1016/j.mimet.2020.106023] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 07/16/2020] [Accepted: 07/24/2020] [Indexed: 11/16/2022]
Abstract
Acinetobacter baumannii causes serious multidrug resistant nosocomial infections around the world. This comprehensive comparative study was designed to assess the effect of temperature (30, 37 and 42 °C), incubation (aerobic and microaerobic) condition and selective [CHROMagar Acinetobacter (CHR) and Leeds Acinetobacter Medium (LAM)] and non-selective [Modified Karmali Agar (MKA)] growth media on the enhanced recovery of A. baumannii from a variety of water (agricultural, recreational, raw drinking intake source, pre-chlorinated and post-chlorinated wastewater effluent) samples spiked with a known number of A. baumannii cells. After spiking each water type with a known number of cells in 10 mL volume, the sample was passed through a membrane filter (pore size 0.45 μm) and filters were placed on different selective media plates and subjected to incubate at various incubation conditions. The results reported in this study show that for all water types tested (except post-chlorinated wastewater effluent), LAM was the most effective selective growth medium in combination with variable temperature and incubation conditions for yielding high recovery rates of A. baumannii cells. Overall, A. baumannii showed that it has a high adaptive capacity to grow on selective and non-selective growth media at different temperature and incubation conditions. The data described in this study suggest that no single incubation condition and growth media would efficiently recover A. baumannii from all environmental water types tested. This data also indicate that selective growth media and incubation condition can significantly affect the recovery of A. baumannii. Differences in recovery of A. baumannii observed in this study which appeared to be dependent on the temperature and environmental characteristics of incubation as well as the sample type, suggest the need for caution when comparing recovery using different protocols.
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Affiliation(s)
- Thomas Benoit
- Ottawa Research and Development Centre (ORDC), Agriculture and Agri-Food Canada, Ottawa, ON, Canada; Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada
| | - Michel Cloutier
- Ottawa Research and Development Centre (ORDC), Agriculture and Agri-Food Canada, Ottawa, ON, Canada
| | - Rhonda Schop
- Ontario Ministry of the Environment, Conservation and Parks, Etobioke, ON, Canada
| | | | - Izhar U H Khan
- Ottawa Research and Development Centre (ORDC), Agriculture and Agri-Food Canada, Ottawa, ON, Canada.
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24
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Wang Y, Lu J, Engelstädter J, Zhang S, Ding P, Mao L, Yuan Z, Bond PL, Guo J. Non-antibiotic pharmaceuticals enhance the transmission of exogenous antibiotic resistance genes through bacterial transformation. THE ISME JOURNAL 2020; 14:2179-2196. [PMID: 32424247 PMCID: PMC7367833 DOI: 10.1038/s41396-020-0679-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/19/2022]
Abstract
Antibiotic resistance is a serious global threat for public health. Considering the high abundance of cell-free DNA encoding antibiotic resistance genes (ARGs) in both clinical and environmental settings, natural transformation is an important horizontal gene transfer pathway to transmit antibiotic resistance. It is acknowledged that antibiotics are key drivers for disseminating antibiotic resistance, yet the contributions of non-antibiotic pharmaceuticals on transformation of ARGs are overlooked. In this study, we report that some commonly consumed non-antibiotic pharmaceuticals, at clinically and environmentally relevant concentrations, significantly facilitated the spread of antibiotic resistance through the uptake of exogenous ARGs. This included nonsteroidal anti-inflammatories, ibuprofen, naproxen, diclofenac, the lipid-lowering drug, gemfibrozil, and the β-blocker propranolol. Based on the results of flow cytometry, whole-genome RNA sequencing and proteomic analysis, the enhanced transformation of ARGs was affiliated with promoted bacterial competence, enhanced stress levels, over-produced reactive oxygen species and increased cell membrane permeability. In addition, a mathematical model was proposed and calibrated to predict the dynamics of transformation during exposure to non-antibiotic pharmaceuticals. Given the high consumption of non-antibiotic pharmaceuticals, these findings reveal new concerns regarding antibiotic resistance dissemination exacerbated by non-antibiotic pharmaceuticals.
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Affiliation(s)
- Yue Wang
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Ji Lu
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Shuai Zhang
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Pengbo Ding
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Likai Mao
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Zhiguo Yuan
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Philip L Bond
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Jianhua Guo
- Advanced Water Management Centre, The University of Queensland, Brisbane, QLD, 4072, Australia.
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Nadhirawaty R, Titah HS. Simultaneous Bioaugmentation and Biostimulation to Remediate Soil Contaminated by Ship Dismantling in Bangkalan District, Indonesia. J Health Pollut 2019; 9:191212. [PMID: 31893173 PMCID: PMC6905141 DOI: 10.5696/2156-9614-9.24.191212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 10/22/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND High concentrations of total petroleum hydrocarbons (TPH), iron (Fe), and manganese (Mn) were identified in soil samples from two shipyards where vessel dismantling activities take place in Tanjungjati Village, Indonesia, and subjected to bioremediation. OBJECTIVES The aim of the present study was to determine whether the combination of surfactant solution, bioaugmentation (a consortium of Bacillus subtilis and Acinetobacter lwoffii), and biostimulation (nutrient amendment and aeration intermittent) would reduce TPH, Fe, and Mn levels from soil contaminated from ship dismantling activities. METHODS Iron and Mn bioavailability were examined according to the Indonesian technical guidelines for soil chemical analysis with the help of atomic absorption spectrophotometry. The n-hexane solvent soil was extracted using the ultrasonic water bath method for TPH analysis. RESULTS The highest removal results achieved were TPH (69.62%), Fe (87.10%), and Mn (29%) for Soil 1 samples and elimination of TPH (28.80%), Fe (65.10%), and Mn (57.38%) for Soil 2 samples using a combination of surfactant solution, bioaugmentation, and biostimulation (nutrient amendment and without aeration intermittent). Iron and Mn removal in the controls was higher than in the treated soils, which showed that Fe and Mn could decrease naturally in both contaminated soils. CONCLUSIONS The present study showed that bioremediation using a combination of surfactant solution, a consortium of Bacillus subtilis, and Acinetobacter lwoffii, as well as a nutrient amendment, has the potential to degrade hydrocarbons in contaminated soil. Furthermore, Bacillus subtilis and Acinetobacter lwoffii consortium used for bioaugmentation have the potential to enhance the degradation of hydrocarbons in soil. COMPETING INTERESTS The authors declare no competing financial interests.
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Affiliation(s)
- Rizqi Nadhirawaty
- Department of Environmental Engineering, Faculty of Civil, Environmental and Geo Engineering, Institut Teknologi Sepuluh Nopember (ITS), Surabaya, Indonesia
| | - Harmin Sulistiyaning Titah
- Department of Environmental Engineering, Faculty of Civil, Environmental and Geo Engineering, Institut Teknologi Sepuluh Nopember (ITS), Surabaya, Indonesia
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Tekielska D, Peňázová E, Kovács T, Křižan B, Čechová J, Eichmeier A. Bacterial Contamination of Plant in vitro Cultures in Commercial Production Detected by High-Throughput Amplicon Sequencing. ACTA UNIVERSITATIS AGRICULTURAE ET SILVICULTURAE MENDELIANAE BRUNENSIS 2019. [DOI: 10.11118/actaun201967041005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Mlynarcik P, Bardon J, Htoutou Sedlakova M, Prochazkova P, Kolar M. Identification of novel OXA-134-like β-lactamases in Acinetobacter lwoffii and Acinetobacter schindleri isolated from chicken litter. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub 2019; 163:141-146. [DOI: 10.5507/bp.2018.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/22/2018] [Indexed: 11/23/2022] Open
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Batra P, Khurana S, Govindaswamy A, Aravinda A, Bajpai V, Ayyanar M, Mathur P, Malhotra R. Antibiotic resistance profile and co-production of extended spectrum beta lactamases and AmpC in Acinetobacter spp. in a level 1 trauma center from India. J Lab Physicians 2019; 11:128-132. [PMID: 31160851 PMCID: PMC6543943 DOI: 10.4103/jlp.jlp_139_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
INTRODUCTION: Acinetobacter baumannii has now emerged as a significant nosocomial pathogen in health-care setting ESP in intensive care units. Rapidly growing resistance among clinical isolates suggests a need to detect resistance mechanisms in this organism. The present study was designed to compare the various phenotypic tests available with the gold standard of genotype. METHODOLOGY: The present study was conducted to include all isolates of Acinetobacter spp. isolated over 3 years. Their resistance to various antibiotics was determined and extended spectrum beta-lactamases (ESBL) and AmpC production in the isolates showing resistance to ceftazidime/ceftriaxone/cefotaxime (CAZ/CTR/CTX) was determined. ESBL and AmpC production was confirmed using polymerase chain reaction (PCR). RESULTS: A total of 154 strains were isolated, and all the strains were tested for ESBL and AmpC detection. Of the strains tested, 15 (9.7%), 17 (11%), 24 (15.6%), 27 (17.5%), 54 (35%), 67 (43.5%), and 72 (46.7%) strains showed ESBL production using CTX/CTX-clavulanate double-disc synergy test (DDST), CTX/CTX-clavulanate E-test, CAZ/CAZ-clavulanate DDST, CAZ/CAZ-clavulanate E-test, Piperacillin/Piperacillin-tazobactam (TZ) DDST, CTR/CTR-Sulbactum DDST, and Piperacillin/Piperacillin-TZ E-test, respectively. 20 (12.9%) and 19 (12.3%) of strains were positive for AmpC production using AmpC disc test and Boronic acid inhibition test, respectively. Genotype analysis using PCR for TEM, SHV, CTXM, PER, and VEB genes was done and 69 (51.5%) strains were positive for TEM gene. DISCUSSION: ESBL detection in Acinetobacter spp. is difficult as standard guidelines for the same are not available unlike in enterobacteriaceae, and there are no zone diameter breakpoints for aztreonam and cefpodoxime. In comparison, piperacillin/piperacillin-TZ E-test had the best sensitivity and specificity for ESBL detection. CONCLUSION: Standard guidelines for ESBL detection in nil fermeners like Acinetobacter spp. must be laid down for ease of detection. Use of piperacillin/piperacillin-tazobactam E-test could be used as one of the standard methods.
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Affiliation(s)
- Priyam Batra
- Department of Lab Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Surbhi Khurana
- Department of Lab Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Aishwarya Govindaswamy
- Department of Lab Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Anjana Aravinda
- Department of Lab Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Vijeta Bajpai
- Department of Lab Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Muruganantham Ayyanar
- Department of Lab Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Purva Mathur
- Department of Lab Medicine, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
| | - Rajesh Malhotra
- Department of Orthopaedics, JPNA Trauma Centre, All India Institute of Medical Sciences, New Delhi, India
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Babaie Z, Delfani S, Rezaei F, Norolahi F, Mahdian S, Shakib P. Molecular Detection of Carbapenem Resistance in Acinetobacter Baumannii Isolated From Patients in Khorramabad City, Iran. Infect Disord Drug Targets 2019; 20:543-549. [PMID: 31099322 DOI: 10.2174/1871526519666190517124314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 02/04/2019] [Accepted: 02/04/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Acinetobacter baumannii is an opportunistic pathogen, which causes a wide range of infections in hospitals, especially in intensive care units. Nowadays, due to the high resistance of Acinetobacter bumanni to antibiotics, this study, in addition to the phenotypic and genotypic investigations of drug resistance, focused on determining the molecular types of Acinetobacter baumannii isolated from patients in Khorramabad city by the pulsed-field gel electrophoresis (PFGE) method. MATERIALS AND METHODS In this cross-sectional study, 50 samples of Acinetobacter baumannii were collected from educational hospitals in Khorramabad city, Iran, from January to August 2015. They were identified in the laboratory using biochemical tests and culture methods. After determining the drug resistance pattern by the disc diffusion method and percentage of resistance genes to carbapenems, Acinetobacter baumannii isolates were analyzed using the PFGE method using the Apa1 enzyme. RESULTS The highest antibiotic resistance observed for Acinetobacter baumannii strains was against ampicillin-sulbactam (100%) and aztreonam (98%). The highest sensitivity was to polymixin B (100%) and colistin (94%), and also to the OXA-51-like gene present in all samples. The OXA-23-like gene was positive in 44 (88%) samples. PFGE results showed that Acinetobacterbaumannii strains had 33 different pulsotype patterns, of which 27 patterns had more than one strain and 23 had only one strain. CONCLUSION Due to the high resistance of Acinetobacter baumannii and its ease of spread and its ability to transfer resistance genes, resistance control methods should be used in the disinfection of hospital areas. Hospital staff should observe hygiene standards and there should also be a reduction in antibiotic use.
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Affiliation(s)
- Zeinab Babaie
- Department of Microbiology, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Somayeh Delfani
- Department of Microbiology, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Faranak Rezaei
- Department of Microbiology, School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Fatemeh Norolahi
- Department of Microbiology, School of Medicine, Pasteur Institute University of Medical Sciences, Tehran, Iran
| | - Somayeh Mahdian
- Department of Microbiology, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran
| | - Pegah Shakib
- Razi Herbal Medicines Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran
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Fariba Akrami, Amirmorteza Ebrahimzadeh Namvar. Acinetobacter baumannii as Nosocomial Pathogenic Bacteria. MOLECULAR GENETICS, MICROBIOLOGY AND VIROLOGY 2019. [DOI: 10.3103/s0891416819020046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Radó J, Kaszab E, Benedek T, Kriszt B, Szoboszlay S. First isolation of carbapenem-resistant Acinetobacter beijerinckii from an environmental sample. Acta Microbiol Immunol Hung 2019; 66:113-130. [PMID: 30816807 DOI: 10.1556/030.66.2019.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The emergence of opportunistic Acinetobacter spp. in healthcare settings poses a significant threat to public health. The major reasons for nosocomial spread of these species are their abilities to develop and transfer drug resistance against various classes of antibiotics. Considering that Acinetobacter spp. are ubiquitous in nature, can utilize several carbon sources, and reach humans via various pathways, our aim was to obtain information about the environmental strains of this genus. Our first step was to develop and test a multistep isolation procedure based on traditional scientific methods. Antibiotic resistance patterns of the isolated strains were determined, as susceptibility to 12 antibiotics of 7 classes was tested by MIC Test Strip method. Altogether 366 samples (groundwater, surface water, and soil) of 24 sites were investigated and a collection of 37 Acinetobacter isolates was obtained. Among others, clinically important human pathogen Acinetobacter spp., such as A. baumannii, A. johnsonii, and A. gyllenbergii were identified. Three environmental strains were determined as multidrug-resistant including a carbapenem-resistant, hemolytic Acinetobacter beijerinckii strain isolated from a hydrocarbon-contaminated groundwater sample. In summary, it has been found that the applied multistep isolation procedure is applicable to isolate various species of Acinetobacter genus. Based on the antibiotic resistance assay, we can conclude that environmental representatives of Acinetobacter spp. are able to develop multidrug resistance, but at a lower rate than their clinical counterparts.
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Affiliation(s)
- Júlia Radó
- 1 Department of Environmental Safety and Ecotoxicology, Szent István University, Gödöllő, Hungary
| | - Edit Kaszab
- 1 Department of Environmental Safety and Ecotoxicology, Szent István University, Gödöllő, Hungary
| | - Tibor Benedek
- 2 Regional University Center of Excellence, Szent István University, Gödöllő, Hungary
| | - Balázs Kriszt
- 1 Department of Environmental Safety and Ecotoxicology, Szent István University, Gödöllő, Hungary
| | - Sándor Szoboszlay
- 1 Department of Environmental Safety and Ecotoxicology, Szent István University, Gödöllő, Hungary
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Lonergan ZR, Nairn BL, Wang J, Hsu YP, Hesse LE, Beavers WN, Chazin WJ, Trinidad JC, VanNieuwenhze MS, Giedroc DP, Skaar EP. An Acinetobacter baumannii, Zinc-Regulated Peptidase Maintains Cell Wall Integrity during Immune-Mediated Nutrient Sequestration. Cell Rep 2019; 26:2009-2018.e6. [PMID: 30784584 PMCID: PMC6441547 DOI: 10.1016/j.celrep.2019.01.089] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 12/21/2018] [Accepted: 01/24/2019] [Indexed: 01/10/2023] Open
Abstract
Acinetobacter baumannii is an important nosocomial pathogen capable of causing wound infections, pneumonia, and bacteremia. During infection, A. baumannii must acquire Zn to survive and colonize the host. Vertebrates have evolved mechanisms to sequester Zn from invading pathogens by a process termed nutritional immunity. One of the most upregulated genes during Zn starvation encodes a putative cell wall-modifying enzyme which we named ZrlA. We found that inactivation of zrlA diminished growth of A. baumannii during Zn starvation. Additionally, this mutant strain displays increased cell envelope permeability, decreased membrane barrier function, and aberrant peptidoglycan muropeptide abundances. This altered envelope increases antibiotic efficacy both in vitro and in an animal model of A. baumannii pneumonia. These results establish ZrlA as a crucial link between nutrient metal uptake and cell envelope homeostasis during A. baumannii pathogenesis, which could be targeted for therapeutic development.
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Affiliation(s)
- Zachery R Lonergan
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA; Microbe-Host Interactions Training Program, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Brittany L Nairn
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jiefei Wang
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - Yen-Pang Hsu
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Laura E Hesse
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA; Microbe-Host Interactions Training Program, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - William N Beavers
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Walter J Chazin
- Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA; Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jonathan C Trinidad
- Department of Chemistry, Indiana University, Bloomington, IN, USA; Laboratory for Biological Mass Spectrometry, Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - Michael S VanNieuwenhze
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - David P Giedroc
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA; Department of Chemistry, Indiana University, Bloomington, IN, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA; Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, TN, USA.
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Van Assche A, Crauwels S, De Brabanter J, Willems KA, Lievens B. Characterization of the bacterial community composition in water of drinking water production and distribution systems in Flanders, Belgium. Microbiologyopen 2018; 8:e00726. [PMID: 30318762 PMCID: PMC6528567 DOI: 10.1002/mbo3.726] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 08/09/2018] [Accepted: 08/09/2018] [Indexed: 12/25/2022] Open
Abstract
The quality of drinking water is influenced by its chemical and microbial composition which in turn may be affected by the source water and the different processes applied in drinking water purification systems. In this study, we investigated the bacterial diversity in different water samples from the production and distribution chain of thirteen drinking water production and distribution systems from Flanders (Belgium) that use surface water or groundwater as source water. Water samples were collected over two seasons from the source water, the processed drinking water within the production facility and out of the tap in houses along its distribution network. 454‐pyrosequencing of 16S ribosomal RNA gene sequences revealed a total of 1,570 species‐level bacterial operational taxonomic units. Strong differences in community composition were found between processed drinking water samples originating from companies that use surface water and other that use groundwater as source water. Proteobacteria was the most abundant phylum in all samples. Yet, several phyla including Actinobacteria were significantly more abundant in surface water while Cyanobacteria were more abundant in surface water and processed water originating from surface water. Gallionella, Acinetobacter, and Pseudomonas were the three most abundant genera detected. Members of the Acinetobacter genus were even found at a relative read abundance of up to 47.5% in processed water samples, indicating a general occurrence of Acinetobacter in drinking water (systems).
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Affiliation(s)
- Ado Van Assche
- Laboratory for Process Microbial Ecology and Bioinspirational Management (PME & BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, Sint-Katelijne-Waver, Belgium
| | - Sam Crauwels
- Laboratory for Process Microbial Ecology and Bioinspirational Management (PME & BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, Sint-Katelijne-Waver, Belgium
| | - Joseph De Brabanter
- Department of Electrical Engineering (ESAT - STADIUS), KU Leuven, Leuven, Belgium
| | - Kris A Willems
- Laboratory for Process Microbial Ecology and Bioinspirational Management (PME & BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, Sint-Katelijne-Waver, Belgium
| | - Bart Lievens
- Laboratory for Process Microbial Ecology and Bioinspirational Management (PME & BIM), Department of Microbial and Molecular Systems (M2S), KU Leuven, Campus De Nayer, Sint-Katelijne-Waver, Belgium
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Cao S, Geng Y, Yu Z, Deng L, Gan W, Wang K, Ou Y, Chen D, Huang X, Zuo Z, He M, Lai W. Acinetobacter lwoffii, an emerging pathogen for fish in Schizothorax genus in China. Transbound Emerg Dis 2018; 65:1816-1822. [PMID: 30239149 DOI: 10.1111/tbed.12957] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 06/14/2018] [Accepted: 06/18/2018] [Indexed: 11/27/2022]
Abstract
Acinetobacter lwoffii, a serious human pathogen, has been identified as a cause of nosocomial infections such as bacteremia, pneumonia and meningitis. There are only a few studies reporting A. lwoffii as a pathogen of fish. During 2016 and 2017, six bacterial strains, isolated from diseased fish of the Schizothorax genus, were identified as A. lwoffii by morphology, biochemical tests, 16S rDNA and gyrB gene sequencing analysis. One of these isolates was selected for experimental infection of Sclizothorax prenanti, Schizothorax davidi and Schizothorax wangchiachii, to confirm its pathogenicity. Experimentally infected fish showed similar symptoms to those observed in fish after natural outbreaks. Susceptibility of the isolates to 14 antibiotics was tested using a disc diffusion method; all isolates were resistant to cephalothin, aminoglycosides and β-lactams, and sensitive only to some fluoroquinolones and tetracyclines. Histological examination revealed that A. lwoffii infection could cause pathological lesions in multiple organs and tissues, especially in liver, kidney, spleen and heart. These lesions included extensive haemorrhage, vacuolar degeneration, necrosis and inflammatory cell infiltration. To our knowledge, this is the first report on A. lwoffii as a virulent pathogen for fish of the Schizothorax genus.
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Affiliation(s)
- Shiqi Cao
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Yi Geng
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Zehui Yu
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Longjun Deng
- Yalong River Hydropower Development Company Ltd., Chengdu, Sichuan, China
| | - Weixiong Gan
- Yalong River Hydropower Development Company Ltd., Chengdu, Sichuan, China
| | - Kaiyu Wang
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Yangping Ou
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Defang Chen
- Department of Aquaculture, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Xiaoli Huang
- Department of Aquaculture, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Zhicai Zuo
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Min He
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
| | - Weiming Lai
- College of Veterinary Medicine, Sichuan Agricultural University, Wenjiang, Sichuan, China
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A Light-Regulated Type I Pilus Contributes to Acinetobacter baumannii Biofilm, Motility, and Virulence Functions. Infect Immun 2018; 86:IAI.00442-18. [PMID: 29891547 DOI: 10.1128/iai.00442-18] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 06/08/2018] [Indexed: 11/20/2022] Open
Abstract
Transcriptional analyses of Acinetobacter baumannii ATCC 17978 showed that the expression of A1S_2091 was enhanced in cells cultured in darkness at 24°C through a process that depended on the BlsA photoreceptor. Disruption of A1S_2091, a component of the A1S_2088-A1S_2091 polycistronic operon predicted to code for a type I chaperone/usher pilus assembly system, abolished surface motility and pellicle formation but significantly enhanced biofilm formation on plastic by bacteria cultured in darkness. Based on these observations, the A1S_2088-A1S_2091 operon was named the photoregulated pilus ABCD (prpABCD) operon, with A1S_2091 coding for the PrpA pilin subunit. Unexpectedly, comparative analyses of ATCC 17978 and prpA isogenic mutant cells cultured at 37°C showed the expression of light-regulated biofilm biogenesis and motility functions under a temperature condition that drastically affects BlsA production and its light-sensing activity. These assays also suggest that ATCC 17978 cells produce alternative light-regulated adhesins and/or pilus systems that enhance bacterial adhesion and biofilm formation at both 24°C and 37°C on plastic as well as on the surface of polarized A549 alveolar epithelial cells, where the formation of bacterial filaments and cell chains was significantly enhanced. The inactivation of prpA also resulted in a significant reduction in virulence when tested by using the Galleria mellonella virulence model. All these observations provide strong evidence showing the capacity of A. baumannii to sense light and interact with biotic and abiotic surfaces using undetermined alternative sensing and regulatory systems as well as alternative adherence and motility cellular functions that allow this pathogen to persist in different ecological niches.
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Asif M, Alvi IA, Rehman SU. Insight into Acinetobacter baumannii: pathogenesis, global resistance, mechanisms of resistance, treatment options, and alternative modalities. Infect Drug Resist 2018; 11:1249-1260. [PMID: 30174448 PMCID: PMC6110297 DOI: 10.2147/idr.s166750] [Citation(s) in RCA: 168] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Acinetobacter baumannii, once considered a low-category pathogen, has emerged as an obstinate infectious agent. The scientific community is paying more attention to this pathogen due to its stubbornness to last resort antimicrobials, including carbapenems, colistin, and tigecycline, its high prevalence of infections in the hospital setting, and significantly increased rate of community-acquired infections by this organism over the past decade. It has given the fear of pre-antibiotic era to the world. To further enhance our understanding about this pathogen, in this review, we discuss its taxonomy, pathogenesis, current treatment options, global resistance rates, mechanisms of its resistance against various groups of antimicrobials, and future therapeutics.
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Affiliation(s)
- Muhammad Asif
- Department of Microbiology and Molecular Genetics, University of the Punjab, Lahore, Pakistan,
- Department of Pathology, King Edward Medical University, Lahore, Pakistan
| | - Iqbal Ahmad Alvi
- Department of Microbiology and Molecular Genetics, University of the Punjab, Lahore, Pakistan,
- Department of Microbiology, Hazara University, Mansehra, Pakistan
| | - Shafiq Ur Rehman
- Department of Microbiology and Molecular Genetics, University of the Punjab, Lahore, Pakistan,
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Abstract
Acinetobacter baumannii has become an important pathogen in hospitals worldwide, where the incidence of these infections has been increasing. A. baumannii infections have become exceedingly difficult to treat due to a rapid increase in the frequency of multidrug- and pan-resistant isolates. This has prompted the World Health Organization to list A. baumannii as the top priority for the research and development of new antibiotics. This study reports for the first time a detailed analysis of aminoglycoside heteroresistance in A. baumannii. We define the mechanistic basis for heteroresistance, where the aadB(ant2″)Ia gene encoding an aminoglycoside adenylyltransferase becomes highly amplified in a RecA-dependent manner. Remarkably, this amplification of 20 to 40 copies occurs stochastically in 1/200 cells in the absence of antibiotic selection. In addition, we provide evidence for a second RecA-independent mechanism for aminoglycoside heteroresistance. This study reveals that aminoglycoside resistance in A. baumannii is far more complex than previously realized and has important implications for the use of aminoglycosides in treating A. baumannii infections. Heteroresistance is a phenomenon where a subpopulation of cells exhibits higher levels of antibiotic resistance than the general population. Analysis of tobramycin resistance in Acinetobacter baumannii AB5075 using Etest strips demonstrated that colonies with increased resistance arose at high frequency within the zone of growth inhibition. The presence of a resistant subpopulation was confirmed by population analysis profiling (PAP). The tobramycin-resistant subpopulation was cross resistant to gentamicin but not amikacin. The increased tobramycin resistance phenotype was highly unstable, and cells reverted to a less resistant population at frequencies of 60 to 90% after growth on nonselective media. Furthermore, the frequency of the resistant subpopulation was not increased by preincubation with subinhibitory concentrations of tobramycin. The tobramycin-resistant subpopulation was shown to replicate during the course of antibiotic treatment, demonstrating that these were not persister cells. In A. baumannii AB5075, a large plasmid (p1AB5075) carries aadB, a 2″-nucleotidyltransferase that confers resistance to both tobramycin and gentamicin but not amikacin. The aadB gene is part of an integron and is carried adjacent to four additional resistance genes that are all flanked by copies of an integrase gene. In isolates with increased resistance, this region was highly amplified in a RecA-dependent manner. However, in a recA mutant, colonies with unstable tobramycin resistance arose by a mechanism that did not involve amplification of this region. These data indicate that tobramycin heteroresistance occurs by at least two mechanisms in A. baumannii, and future studies to determine its effect on patient outcomes are warranted. IMPORTANCEAcinetobacter baumannii has become an important pathogen in hospitals worldwide, where the incidence of these infections has been increasing. A. baumannii infections have become exceedingly difficult to treat due to a rapid increase in the frequency of multidrug- and pan-resistant isolates. This has prompted the World Health Organization to list A. baumannii as the top priority for the research and development of new antibiotics. This study reports for the first time a detailed analysis of aminoglycoside heteroresistance in A. baumannii. We define the mechanistic basis for heteroresistance, where the aadB(ant2″)Ia gene encoding an aminoglycoside adenylyltransferase becomes highly amplified in a RecA-dependent manner. Remarkably, this amplification of 20 to 40 copies occurs stochastically in 1/200 cells in the absence of antibiotic selection. In addition, we provide evidence for a second RecA-independent mechanism for aminoglycoside heteroresistance. This study reveals that aminoglycoside resistance in A. baumannii is far more complex than previously realized and has important implications for the use of aminoglycosides in treating A. baumannii infections.
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Li X, Tang Y, Lu X. Insight into Identification of Acinetobacter Species by Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) in the Clinical Laboratory. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:1546-1553. [PMID: 29633221 DOI: 10.1007/s13361-018-1911-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Revised: 01/30/2018] [Accepted: 01/30/2018] [Indexed: 06/08/2023]
Abstract
Currently, the capability of identification for Acinetobacter species using MALDI-TOF MS still remains unclear in clinical laboratories due to certain elusory phenomena. Thus, we conducted this research to evaluate this technique and reveal the causes of misidentification. Briefly, a total of 788 Acinetobacter strains were collected and confirmed at the species level by 16S rDNA and rpoB sequencing, and subsequently compared to the identification by MALDI-TOF MS using direct smear and bacterial extraction pretreatments. Cluster analysis was performed based on the mass spectra and 16S rDNA to reflect the diversity among different species. Eventually, 19 Acinetobacter species were confirmed, including 6 species unavailable in Biotyper 3.0 database. Another novel species was observed, temporarily named A. corallinus. The accuracy of identification for Acinetobacter species using MALDI-TOF MS was 97.08% (765/788), regardless of which pretreatment was applied. The misidentification only occurred on 3 A. parvus strains and 20 strains of species unavailable in the database. The proportions of strains with identification score ≥ 2.000 using direct smear and bacterial extraction pretreatments were 86.04% (678/788) and 95.43% (752/788), χ2 = 41.336, P < 0.001. The species similar in 16 rDNA were discriminative from the mass spectra, such as A. baumannii & A. junii, A. pittii & A. calcoaceticus, and A. nosocomialis & A. seifertii. Therefore, using MALDI-TOF MS to identify Acinetobacter strains isolated from clinical samples was deemed reliable. Misidentification occurred occasionally due to the insufficiency of the database rather than sample extraction failure. We suggest gene sequencing should be performed when the identification score is under 2.000 even when using bacterial extraction pretreatment. Graphical Abstract ᅟ.
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Affiliation(s)
- Xiuyuan Li
- Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Legation Street 1#, Beijing, Dongcheng District, 100730, China
| | - Yanyan Tang
- Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Legation Street 1#, Beijing, Dongcheng District, 100730, China
| | - Xinxin Lu
- Department of Laboratory Medicine, Beijing Tongren Hospital, Capital Medical University, Legation Street 1#, Beijing, Dongcheng District, 100730, China.
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Salto IP, Torres Tejerizo G, Wibberg D, Pühler A, Schlüter A, Pistorio M. Comparative genomic analysis of Acinetobacter spp. plasmids originating from clinical settings and environmental habitats. Sci Rep 2018; 8:7783. [PMID: 29773850 PMCID: PMC5958079 DOI: 10.1038/s41598-018-26180-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/27/2018] [Indexed: 12/20/2022] Open
Abstract
Bacteria belonging to the genus Acinetobacter have become of clinical importance over the last decade due to the development of a multi-resistant phenotype and their ability to survive under multiple environmental conditions. The development of these traits among Acinetobacter strains occurs frequently as a result of plasmid-mediated horizontal gene transfer. In this work, plasmids from nosocomial and environmental Acinetobacter spp. collections were separately sequenced and characterized. Assembly of the sequenced data resulted in 19 complete replicons in the nosocomial collection and 77 plasmid contigs in the environmental collection. Comparative genomic analysis showed that many of them had conserved backbones. Plasmid coding sequences corresponding to plasmid specific functions were bioinformatically and functionally analyzed. Replication initiation protein analysis revealed the predominance of the Rep_3 superfamily. The phylogenetic tree constructed from all Acinetobacter Rep_3 superfamily plasmids showed 16 intermingled clades originating from nosocomial and environmental habitats. Phylogenetic analysis of relaxase proteins revealed the presence of a new sub-clade named MOBQAci, composed exclusively of Acinetobacter relaxases. Functional analysis of proteins belonging to this group showed that they behaved differently when mobilized using helper plasmids belonging to different incompatibility groups.
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Affiliation(s)
- Ileana P Salto
- IBBM (Instituto de Biotecnología y Biología Molecular), CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina
| | - Gonzalo Torres Tejerizo
- IBBM (Instituto de Biotecnología y Biología Molecular), CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Daniel Wibberg
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Alfred Pühler
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Andreas Schlüter
- Center for Biotechnology (CeBiTec), Bielefeld University, Genome Research of Industrial Microorganisms, Universitätsstr. 27, D-33615, Bielefeld, Germany
| | - Mariano Pistorio
- IBBM (Instituto de Biotecnología y Biología Molecular), CCT-CONICET-La Plata, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina.
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Zolfo M, Asnicar F, Manghi P, Pasolli E, Tett A, Segata N. Profiling microbial strains in urban environments using metagenomic sequencing data. Biol Direct 2018; 13:9. [PMID: 29743119 PMCID: PMC5944035 DOI: 10.1186/s13062-018-0211-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 04/26/2018] [Indexed: 11/10/2022] Open
Abstract
Background The microbial communities populating human and natural environments have been extensively characterized with shotgun metagenomics, which provides an in-depth representation of the microbial diversity within a sample. Microbes thriving in urban environments may be crucially important for human health, but have received less attention than those of other environments. Ongoing efforts started to target urban microbiomes at a large scale, but the most recent computational methods to profile these metagenomes have never been applied in this context. It is thus currently unclear whether such methods, that have proven successful at distinguishing even closely related strains in human microbiomes, are also effective in urban settings for tasks such as cultivation-free pathogen detection and microbial surveillance. Here, we aimed at a) testing the currently available metagenomic profiling tools on urban metagenomics; b) characterizing the organisms in urban environment at the resolution of single strain and c) discussing the biological insights that can be inferred from such methods. Results We applied three complementary methods on the 1614 metagenomes of the CAMDA 2017 challenge. With MetaMLST we identified 121 known sequence-types from 15 species of clinical relevance. For instance, we identified several Acinetobacter strains that were close to the nosocomial opportunistic pathogen A. nosocomialis. With StrainPhlAn, a generalized version of the MetaMLST approach, we inferred the phylogenetic structure of Pseudomonas stutzeri strains and suggested that the strain-level heterogeneity in environmental samples is higher than in the human microbiome. Finally, we also probed the functional potential of the different strains with PanPhlAn. We further showed that SNV-based and pangenome-based profiling provide complementary information that can be combined to investigate the evolutionary trajectories of microbes and to identify specific genetic determinants of virulence and antibiotic resistances within closely related strains. Conclusion We show that strain-level methods developed primarily for the analysis of human microbiomes can be effective for city-associated microbiomes. In fact, (opportunistic) pathogens can be tracked and monitored across many hundreds of urban metagenomes. However, while more effort is needed to profile strains of currently uncharacterized species, this work poses the basis for high-resolution analyses of microbiomes sampled in city and mass transportation environments. Reviewers This article was reviewed by Alexandra Bettina Graf, Daniel Huson and Trevor Cickovski. Electronic supplementary material The online version of this article (10.1186/s13062-018-0211-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Moreno Zolfo
- Centre for Integrative Biology, University of Trento, Via Sommarive 9, 38123, Trento, TN, Italy
| | - Francesco Asnicar
- Centre for Integrative Biology, University of Trento, Via Sommarive 9, 38123, Trento, TN, Italy
| | - Paolo Manghi
- Centre for Integrative Biology, University of Trento, Via Sommarive 9, 38123, Trento, TN, Italy
| | - Edoardo Pasolli
- Centre for Integrative Biology, University of Trento, Via Sommarive 9, 38123, Trento, TN, Italy
| | - Adrian Tett
- Centre for Integrative Biology, University of Trento, Via Sommarive 9, 38123, Trento, TN, Italy
| | - Nicola Segata
- Centre for Integrative Biology, University of Trento, Via Sommarive 9, 38123, Trento, TN, Italy.
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Leight AK, Crump BC, Hood RR. Assessment of Fecal Indicator Bacteria and Potential Pathogen Co-Occurrence at a Shellfish Growing Area. Front Microbiol 2018; 9:384. [PMID: 29593669 PMCID: PMC5861211 DOI: 10.3389/fmicb.2018.00384] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 02/20/2018] [Indexed: 01/04/2023] Open
Abstract
Routine monitoring of shellfish growing waters for bacteria indicative of human sewage pollution reveals little about the bacterial communities that co-occur with these indicators. This study investigated the bacterial community, potential pathogens, and fecal indicator bacteria in 40 water samples from a shellfish growing area in the Chesapeake Bay, USA. Bacterial community composition was quantified with deep sequencing of 16S rRNA gene amplicons, and absolute gene abundances were estimated with an internal standard (Thermus thermophilus genomes). Fecal coliforms were quantified by culture, and Vibrio vulnificus and V. parahaemolyticus with quantitative PCR. Fecal coliforms and V. vulnificus were detected in most samples, and a diverse assemblage of potential human pathogens were detected in all samples. These taxa followed two general patterns of abundance. Fecal coliforms and 16S rRNA genes for Enterobacteriaceae, Aeromonas, Arcobacter, Staphylococcus, and Bacteroides increased in abundance after a 1.3-inch rain event in May, and, for some taxa, after smaller rain events later in the season, suggesting that these are allochthonous organisms washed in from land. Clostridiaceae and Mycobacterium 16S rRNA gene abundances increased with day of the year and were not positively related to rainfall, suggesting that these are autochthonous organisms. Other groups followed both patterns, such as Legionella. Fecal coliform abundance did not correlate with most other taxa, but were extremely high following the large rainstorm in May when they co-occurred with a broad range of potential pathogen groups. V. vulnificus were absent during the large rainstorm, and did not correlate with 16S rRNA abundances of Vibrio spp. or most other taxa. These results highlight the complex nature of bacterial communities and the limited utility of using specific bacterial groups as indicators of pathogen presence.
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Affiliation(s)
- Andrew K Leight
- Cooperative Oxford Laboratory, National Ocean Service/National Centers for Coastal Ocean Science, National Oceanic and Atmospheric Administration (NOAA), Oxford, MD, United States.,Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, MD, United States
| | - Byron C Crump
- College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, United States
| | - Raleigh R Hood
- Horn Point Laboratory, University of Maryland Center for Environmental Science, Cambridge, MD, United States
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Wepking C, Avera B, Badgley B, Barrett JE, Franklin J, Knowlton KF, Ray PP, Smitherman C, Strickland MS. Exposure to dairy manure leads to greater antibiotic resistance and increased mass-specific respiration in soil microbial communities. Proc Biol Sci 2018; 284:rspb.2016.2233. [PMID: 28356447 DOI: 10.1098/rspb.2016.2233] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 02/27/2017] [Indexed: 01/08/2023] Open
Abstract
Intensifying livestock production to meet the demands of a growing global population coincides with increases in both the administration of veterinary antibiotics and manure inputs to soils. These trends have the potential to increase antibiotic resistance in soil microbial communities. The effect of maintaining increased antibiotic resistance on soil microbial communities and the ecosystem processes they regulate is unknown. We compare soil microbial communities from paired reference and dairy manure-exposed sites across the USA. Given that manure exposure has been shown to elicit increased antibiotic resistance in soil microbial communities, we expect that manure-exposed sites will exhibit (i) compositionally different soil microbial communities, with shifts toward taxa known to exhibit resistance; (ii) greater abundance of antibiotic resistance genes; and (iii) corresponding maintenance of antibiotic resistance would lead to decreased microbial efficiency. We found that bacterial and fungal communities differed between reference and manure-exposed sites. Additionally, the β-lactam resistance gene ampC was 5.2-fold greater under manure exposure, potentially due to the use of cephalosporin antibiotics in dairy herds. Finally, ampC abundance was positively correlated with indicators of microbial stress, and microbial mass-specific respiration, which increased 2.1-fold under manure exposure. These findings demonstrate that the maintenance of antibiotic resistance associated with manure inputs alters soil microbial communities and ecosystem function.
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Affiliation(s)
- Carl Wepking
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Bethany Avera
- Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, CO 80521, USA
| | - Brian Badgley
- Department of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - John E Barrett
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - Josh Franklin
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA.,Department of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | | | - Partha P Ray
- Animal, Dairy and Food Chain Sciences, School of Agriculture, Policy and Development, University of Reading, Early Gate, Reading RG6 6AR, UK
| | - Crystal Smitherman
- Department of Crop and Soil Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, USA
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Lipopolysaccharide from Crypt-Specific Core Microbiota Modulates the Colonic Epithelial Proliferation-to-Differentiation Balance. mBio 2017; 8:mBio.01680-17. [PMID: 29042502 PMCID: PMC5646255 DOI: 10.1128/mbio.01680-17] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We identified a crypt-specific core microbiota (CSCM) dominated by strictly aerobic, nonfermentative bacteria in murine cecal and proximal colonic (PC) crypts and hypothesized that, among its possible functions, it may affect epithelial regeneration. In the present work, we isolated representative CSCM strains using selective media based upon our initial 16S rRNA-based molecular identification (i.e., Acinetobacter, Delftia, and Stenotrophomonas). Their tropism for the crypt was confirmed, and their influence on epithelial regeneration was demonstrated in vivo by monocolonization of germfree mice. We also showed that lipopolysaccharide (LPS), through its endotoxin activity, was the dominant bacterial agonist controlling proliferation. The relevant molecular mechanisms were analyzed using colonic crypt-derived organoids exposed to bacterial sonicates or highly purified LPS as agonists. We identified a Toll-like receptor 4 (TLR4)-dependent program affecting crypts at different stages of epithelial differentiation. LPS played a dual role: it repressed cell proliferation through RIPK3-mediated necroptosis of stem cells and cells of the transit-amplifying compartment and concurrently enhanced cell differentiation, particularly the goblet cell lineage. The LPS from crypt-specific core microbiota controls intestinal epithelium proliferation through necroptosis of stem cells and enhances cell differentiation, mainly the goblet cell lineage.
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Grande Burgos MJ, López Aguayo MDC, Pérez Pulido R, Galvez A, Lucas R. Analysis of the microbiota of refrigerated chopped parsley after treatments with a coating containing enterocin AS-48 or by high-hydrostatic pressure. Food Res Int 2017; 99:91-97. [DOI: 10.1016/j.foodres.2017.05.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/17/2017] [Accepted: 05/18/2017] [Indexed: 12/26/2022]
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Munier AL, Biard L, Rousseau C, Legrand M, Lafaurie M, Lomont A, Donay JL, de Beaugrenier E, Flicoteaux R, Mebazaa A, Mimoun M, Molina JM. Incidence, risk factors, and outcome of multidrug-resistant Acinetobacter baumannii acquisition during an outbreak in a burns unit. J Hosp Infect 2017; 97:226-233. [PMID: 28751010 DOI: 10.1016/j.jhin.2017.07.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 07/19/2017] [Indexed: 12/31/2022]
Abstract
BACKGROUND Multidrug-resistant Acinetobacter baumannii (MR-AB) can cause outbreaks in a burns unit. AIM To study the incidence, risk factors and outcome of MR-AB colonization during an outbreak. METHODS A prospective study was conducted from April to November 2014 in a burns unit in Paris. Weekly surveillance cultures of patients and their environment were performed. MR-AB acquisition, discharge, or death without MR-AB colonization were considered as competing events. To identify risk factors for colonization, baseline characteristics and time-dependent variables were investigated in univariate and multivariate analyses using Cox models. MR-AB strains were genotypically compared using multi-locus sequence typing. FINDINGS Eighty-six patients were admitted in the burns unit during the study period. Among 77 patients without MR-AB colonization at admission, 25 (32%) acquired MR-AB with a cumulative incidence of 30% at 28 days (95% CI: 20-40). Median time to MR-AB acquisition was 13 days (range: 5-34). In multivariate analysis, risk factors for MR-AB acquisition were ≥2 skin graft procedures performed [hazard ratio (HR): 2.97; 95% confidence interval (CI): 1.10-8.00; P = 0.032] and antibiotic therapy during hospitalization (HR: 4.42; 95% CI: 1.19-16.4; P = 0.026). A major sequence type of MR-AB (ST2) was found in 94% and 92% of patients and environmental strains, respectively, with all strains harbouring the blaOXA-23 gene. MR-AB colonization increased length of hospitalization (HR: 0.32; 95% CI: 0.17-0.58; P = 0.0002) by a median of 12 days. CONCLUSION A high incidence of MR-AB acquisition was seen during this outbreak with most strains from patients and their environment belonging to single sequence type. MR-AB colonization was associated with more skin graft procedures, antibiotic use, and prolonged hospitalization.
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Affiliation(s)
- A-L Munier
- Infectious Disease Department, St Louis Hospital, APHP and University Paris Diderot, Paris, France.
| | - L Biard
- Department of Biostatistics, St Louis Hospital, APHP and University Paris Diderot, Paris, France
| | - C Rousseau
- Microbiology Department, St Louis Hospital, APHP and EA4065, University Paris Descartes, Paris, France
| | - M Legrand
- Department of Anesthesiology, Critical Care and Burn Unit, St Louis Hospital, APHP and University Paris Diderot, Paris, France; INSERM U942, France
| | - M Lafaurie
- Infectious Disease Department, St Louis Hospital, APHP and University Paris Diderot, Paris, France
| | - A Lomont
- Microbiology Department, St Louis Hospital, APHP and EA4065, University Paris Descartes, Paris, France
| | - J-L Donay
- Microbiology Department, St Louis Hospital, APHP and EA4065, University Paris Descartes, Paris, France
| | - E de Beaugrenier
- Pharmacy Department, St Louis Hospital, APHP and University Paris Diderot, Paris, France
| | - R Flicoteaux
- Department of Biostatistics, St Louis Hospital, APHP and University Paris Diderot, Paris, France
| | - A Mebazaa
- Department of Anesthesiology, Critical Care and Burn Unit, St Louis Hospital, APHP and University Paris Diderot, Paris, France
| | - M Mimoun
- Plastic Surgery Department, St Louis Hospital, APHP and University Paris Diderot, Paris, France
| | - J-M Molina
- Infectious Disease Department, St Louis Hospital, APHP and University Paris Diderot, Paris, France
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Saffarian A, Touchon M, Mulet C, Tournebize R, Passet V, Brisse S, Rocha EPC, Sansonetti PJ, Pédron T. Comparative genomic analysis of Acinetobacter strains isolated from murine colonic crypts. BMC Genomics 2017; 18:525. [PMID: 28697749 PMCID: PMC5505149 DOI: 10.1186/s12864-017-3925-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 07/06/2017] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND A restricted set of aerobic bacteria dominated by the Acinetobacter genus was identified in murine intestinal colonic crypts. The vicinity of such bacteria with intestinal stem cells could indicate that they protect the crypt against cytotoxic and genotoxic signals. Genome analyses of these bacteria were performed to better appreciate their biodegradative capacities. RESULTS Two taxonomically different clusters of Acinetobacter were isolated from murine proximal colonic crypts, one was identified as A. modestus and the other as A. radioresistens. Their identification was performed through biochemical parameters and housekeeping gene sequencing. After selection of one strain of each cluster (A. modestus CM11G and A. radioresistens CM38.2), comparative genomic analysis was performed on whole-genome sequencing data. The antibiotic resistance pattern of these two strains is different, in line with the many genes involved in resistance to heavy metals identified in both genomes. Moreover whereas the operon benABCDE involved in benzoate metabolism is encoded by the two genomes, the operon antABC encoding the anthranilate dioxygenase, and the phenol hydroxylase gene cluster are absent in the A. modestus genomic sequence, indicating that the two strains have different capacities to metabolize xenobiotics. A common feature of the two strains is the presence of a type IV pili system, and the presence of genes encoding proteins pertaining to secretion systems such as Type I and Type II secretion systems. CONCLUSIONS Our comparative genomic analysis revealed that different Acinetobacter isolated from the same biological niche, even if they share a large majority of genes, possess unique features that could play a specific role in the protection of the intestinal crypt.
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Affiliation(s)
- Azadeh Saffarian
- Unité de Pathogénie Microbienne Moléculaire, INSERM U1202, Institut Pasteur, Paris, France
| | - Marie Touchon
- Unité de Génomique Evolutive des Microbes, CNRS, UMR3525, Institut Pasteur, Paris, France
| | - Céline Mulet
- Unité de Pathogénie Microbienne Moléculaire, INSERM U1202, Institut Pasteur, Paris, France
| | - Régis Tournebize
- Unité de Pathogénie Microbienne Moléculaire, INSERM U1202, Imagopole Citech, Institut Pasteur, Paris, France
| | - Virginie Passet
- Unité de Génomique Evolutive des Microbes, CNRS, UMR3525, Institut Pasteur, Paris, France
| | - Sylvain Brisse
- Unité de Génomique Evolutive des Microbes, CNRS, UMR3525, Institut Pasteur, Paris, France
| | - Eduardo P C Rocha
- Unité de Génomique Evolutive des Microbes, CNRS, UMR3525, Institut Pasteur, Paris, France
| | - Philippe J Sansonetti
- Unité de Pathogénie Microbienne Moléculaire, INSERM U1202, Institut Pasteur, Paris, France.,Chaire de Microbiologie et Maladies Infectieuses, Collège de France, Paris, France
| | - Thierry Pédron
- Unité de Pathogénie Microbienne Moléculaire, INSERM U1202, Institut Pasteur, Paris, France.
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Erdönmez D, Rad AY, Aksöz N. Quorum sensing molecules production by nosocomial and soil isolates Acinetobacter baumannii. Arch Microbiol 2017; 199:1325-1334. [PMID: 28688010 DOI: 10.1007/s00203-017-1408-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 06/22/2017] [Accepted: 06/29/2017] [Indexed: 12/31/2022]
Abstract
Acinetobacter species remain alive in hospitals on various surfaces, both dry and moist, forming an important source of hospital infections. These bacteria are naturally resistant to many antibiotic classes. Although the role of the quorum sensing system in regulating the virulence factors of Acinetobacter species has not been fully elucidated, it has been reported that they play a role in bacterial biofilm formation. The biofilm formation helps them to survive under unfavorable growth conditions and antimicrobial treatments. It is based on the accumulation of bacterial communication signal molecules in the area. In this study, we compared the bacterial signal molecules of 50 nosocomial Acinetobacter baumannii strain and 20 A. baumannii strain isolated from soil. The signal molecules were detected by the biosensor bacteria (Chromobacterium violaceum 026, Agrobacterium tumefaciens A136, and Agrobacterium tumefaciens NTL1) and their separation was determined by thin-layer chromatography. As a result, it has been found that soil-borne isolates can produce 3-oxo-C8-AHL and C8-AHL, whereas nosocomial-derived isolates can produce long-chain signals such as C10-AHL, C12-AHL, C14-AHL and C16-AHL. According to these results, it is possible to understand that these signal molecules are found in the infection caused by A. baumannii. The inhibition of this signaling molecules in a communication could use to prevent multiple antibiotic resistance of these bacteria.
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Affiliation(s)
- Demet Erdönmez
- Department of Biology, Institute of Science, Hacettepe University, Ankara, Turkey.
| | - Abbas Yousefi Rad
- Department of Medical Microbiology, Medical Faculty, Yüksek İhtisas University, Ankara, Turkey
| | - Nilüfer Aksöz
- Department of Biology, Faculty of Science, Hacettepe University, Ankara, Turkey
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Raro OHF, Gallo SW, Ferreira CAS, Oliveira SDD. Carbapenem-resistant Acinetobacter baumannii contamination in an intensive care unit. Rev Soc Bras Med Trop 2017; 50:167-172. [DOI: 10.1590/0037-8682-0329-2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 02/08/2017] [Indexed: 11/22/2022] Open
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Xu J, Wei Y, Jia H, Xiao L, Gong D. A new perspective on studying burial environment before archaeological excavation: analyzing bacterial community distribution by high-throughput sequencing. Sci Rep 2017; 7:41691. [PMID: 28169321 PMCID: PMC5294632 DOI: 10.1038/srep41691] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 12/23/2016] [Indexed: 02/01/2023] Open
Abstract
Burial conditions play a crucial role in archaeological heritage preservation. Especially, the microorganisms were considered as the leading causes which incurred degradation and vanishment of historic materials. In this article, we analyzed bacterial diversity and community structure from M1 of Wangshanqiao using 16 S rRNA gene amplicon sequencing. The results indicated that microbial communities in burial conditions were diverse among four different samples. The samples from the robber hole varied most obviously in community structure both in Alpha and Beta diversity. In addition, the dominant phylum in different samples were Proteobacteria, Actinobacteria and Bacteroidetes, respectively. Moreover, the study implied that historical materials preservation conditions had connections with bacterial community distribution. At the genus level, Acinetobacter might possess high ability in degrading organic culture heritage in burial conditions, while Bacteroides were associated closely with favorable preservation conditions. This method contributes to fetch information which would never recover after excavation, and it will help to explore microbial degradation on precious organic culture heritage and further our understanding of archaeological burial environment. The study also indicates that robbery has a serious negative impact on burial remains.
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Affiliation(s)
- Jinjin Xu
- Department of History of Science and Scientific Archaeology, University of Science and Technology of China, Hefei, 230026 China
| | - Yanfei Wei
- Department of History of Science and Scientific Archaeology, University of Science and Technology of China, Hefei, 230026 China.,Jingzhou Preservation Centre of Cultural Relics, Jingzhou, 434020 China
| | | | - Lin Xiao
- Chengdu Institute of Cultural Relics and Archaeology, Chengdu, 610000 China
| | - Decai Gong
- Department of History of Science and Scientific Archaeology, University of Science and Technology of China, Hefei, 230026 China
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Genetic Dissection of the Type VI Secretion System in Acinetobacter and Identification of a Novel Peptidoglycan Hydrolase, TagX, Required for Its Biogenesis. mBio 2016; 7:mBio.01253-16. [PMID: 27729508 PMCID: PMC5061870 DOI: 10.1128/mbio.01253-16] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread secretory apparatus produced by Gram-negative bacteria that has emerged as a potent mediator of antibacterial activity during interbacterial interactions. Most Acinetobacter species produce a genetically conserved T6SS, although the expression and functionality of this system vary among different strains. Some pathogenic Acinetobacter baumannii strains activate this secretion system via the spontaneous loss of a plasmid carrying T6SS repressors. In this work, we compared the expression of T6SS-related genes via transcriptome sequencing and differential proteomics in cells with and without the plasmid. This approach, together with the mutational analysis of the T6SS clusters, led to the determination of the genetic components required to elaborate a functional T6SS in the nosocomial pathogen A. baumannii and the nonpathogen A. baylyi By constructing a comprehensive combination of mutants with changes in the T6SS-associated vgrG genes, we delineated their relative contributions to T6SS function. We further determined the importance of two effectors, including an effector-immunity pair, for antibacterial activity. Our genetic analysis led to the identification of an essential membrane-associated structural component named TagX, which we have characterized as a peptidoglycan hydrolase possessing l,d-endopeptidase activity. TagX shows homology to known bacteriophage l,d-endopeptidases and is conserved in the T6SS clusters of several bacterial species. We propose that TagX is the first identified enzyme that fulfills the important role of enabling the transit of T6SS machinery across the peptidoglycan layer of the T6SS-producing bacterium. IMPORTANCE Acinetobacter baumannii is one of the most troublesome and least investigated multidrug-resistant bacterial pathogens. We have previously shown that A. baumannii employs a T6SS to eliminate competing bacteria. Here we provide a comprehensive analysis of the components of the T6SS of Acinetobacter, and our results provide genetic and functional insights into the Acinetobacter T6SS. Through this analysis, we identified a novel peptidoglycan hydrolase, TagX, that is required for biogenesis of the T6SS apparatus. This is the first peptidoglycanase specialized in T6SS function identified in any species. We propose that this enzyme is required for the spatially and temporally regulated digestion of peptidoglycan to allow assembly of the T6SS machinery.
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