51
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New antibiotics from Nature’s chemical inventory. Bioorg Med Chem 2016; 24:6227-6252. [DOI: 10.1016/j.bmc.2016.09.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/07/2016] [Indexed: 01/07/2023]
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52
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Kamoshida G, Tansho-Nagakawa S, Kikuchi-Ueda T, Nakano R, Hikosaka K, Nishida S, Ubagai T, Higashi S, Ono Y. A novel bacterial transport mechanism of Acinetobacter baumannii via activated human neutrophils through interleukin-8. J Leukoc Biol 2016; 100:1405-1412. [PMID: 27365529 DOI: 10.1189/jlb.4ab0116-023rr] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 06/01/2016] [Accepted: 06/13/2016] [Indexed: 01/08/2023] Open
Abstract
Hospital-acquired infections as a result of Acinetobacter baumannii have become problematic because of high rates of drug resistance. Although neutrophils play a critical role in early protection against bacterial infection, their interactions with A. baumannii remain largely unknown. To elucidate the interactions between A. baumannii and human neutrophils, we cocultured these cells and analyzed them by microscopy and flow cytometry. We found that A. baumannii adhered to neutrophils. We next examined neutrophil and A. baumannii infiltration into Matrigel basement membranes by an in vitro transmigration assay. Neutrophils were activated by A. baumannii, and invasion was enhanced. More interestingly, A. baumannii was transported together by infiltrating neutrophils. Furthermore, we observed by live cell imaging that A. baumannii and neutrophils moved together. In addition, A. baumannii-activated neutrophils showed increased IL-8 production. The transport of A. baumannii was suppressed by inhibiting neutrophil infiltration by blocking the effect of IL-8. A. baumannii appears to use neutrophils for transport by activating these cells via IL-8. In this study, we revealed a novel bacterial transport mechanism that A. baumannii exploits human neutrophils by adhering to and inducing IL-8 release for bacterial portage. This mechanism might be a new treatment target.
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Affiliation(s)
- Go Kamoshida
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan;
| | - Shigeru Tansho-Nagakawa
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan
| | - Takane Kikuchi-Ueda
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan
| | - Ryuichi Nakano
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan.,Department of Microbiology and Infectious Diseases, Nara Medical University, Nara, Japan
| | - Kenji Hikosaka
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan.,Department of Infection and Host Defense, Graduate School of Medicine, Chiba University, Chiba, Japan; and
| | - Satoshi Nishida
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan
| | - Tsuneyuki Ubagai
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan
| | - Shouichi Higashi
- Graduate School of Nanobioscience, Yokohama City University, Yokohama, Japan
| | - Yasuo Ono
- Department of Microbiology and Immunology, Teikyo University School of Medicine, Tokyo, Japan
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53
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Bacterial and archaeal communities in the deep-sea sediments of inactive hydrothermal vents in the Southwest India Ridge. Sci Rep 2016; 6:25982. [PMID: 27169490 PMCID: PMC4864381 DOI: 10.1038/srep25982] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 04/25/2016] [Indexed: 02/01/2023] Open
Abstract
Active deep-sea hydrothermal vents harbor abundant thermophilic and hyperthermophilic microorganisms. However, microbial communities in inactive hydrothermal vents have not been well documented. Here, we investigated bacterial and archaeal communities in the two deep-sea sediments (named as TVG4 and TVG11) collected from inactive hydrothermal vents in the Southwest India Ridge using the high-throughput sequencing technology of Illumina MiSeq2500 platform. Based on the V4 region of 16S rRNA gene, sequence analysis showed that bacterial communities in the two samples were dominated by Proteobacteria, followed by Bacteroidetes, Actinobacteria and Firmicutes. Furthermore, archaeal communities in the two samples were dominated by Thaumarchaeota and Euryarchaeota. Comparative analysis showed that (i) TVG4 displayed the higher bacterial richness and lower archaeal richness than TVG11; (ii) the two samples had more divergence in archaeal communities than bacterial communities. Bacteria and archaea that are potentially associated with nitrogen, sulfur metal and methane cycling were detected in the two samples. Overall, we first provided a comparative picture of bacterial and archaeal communities and revealed their potentially ecological roles in the deep-sea environments of inactive hydrothermal vents in the Southwest Indian Ridge, augmenting microbial communities in inactive hydrothermal vents.
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Darvishi-Khezri H, Alipour A, Emami Zeydi A, Firouzian A, Mahmudi G, Omrani-Nava M. Is type 2 diabetes mellitus in mechanically ventilated adult trauma patients potentially related to the occurrence of ventilator-associated pneumonia? JOURNAL OF RESEARCH IN MEDICAL SCIENCES 2016; 21:19. [PMID: 27904565 PMCID: PMC5121997 DOI: 10.4103/1735-1995.179887] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 09/21/2015] [Accepted: 02/09/2016] [Indexed: 02/02/2023]
Abstract
BACKGROUND Ventilator-associated pneumonia (VAP) is a type of lung infection that typically affects critically ill patients undergoing mechanical ventilation (MV) in the intensive care unit (ICU). Patients with type 2 diabetes mellitus (T2DM) are considered to be more susceptible to several types of infections including community-acquired pneumonia. However, it is not clear whether T2DM is a risk factor for the development of VAP. The purpose of this study was to determine the risk of VAP for diabetic and nondiabetic mechanically ventilated trauma patients. MATERIALS AND METHODS This study is a secondary analysis of a prospective observational study of the history of T2DM in the ICU over a period of 1 year at Imam Khomeini Hospital in Iran. A total of 186 critically ill trauma patients who required at least 48 h of MV were monitored for the occurrence of VAP by their clinical pulmonary infection score (CPIS) until ICU discharge, VAP diagnosis, or death. RESULTS Forty-one of the 186 patients developed VAP. The median time from hospitalization to VAP was 29.09 days (95% CI: 26.27-31.9). The overall incidence of VAP was 18.82 cases per 1,000 days of intubation (95% CI: 13.86-25.57). Risk of VAP in diabetic patients was greater than nondiabetic patients after adjustments for other potential factors [hazard ratio (HR): 10.12 [95% confidence interval (CI): 5.1-20.2); P < 0.0001)]. CONCLUSION The findings show that T2DM is associated with a significant increase in the occurrence of VAP in mechanically ventilated adult trauma patients.
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Affiliation(s)
| | - Abbas Alipour
- Department of Community Medicine, Thalassemia Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Amir Emami Zeydi
- Student Research Committee, Department of Medical-Surgical Nursing, School of Nursing and Midwifery, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Abolfazl Firouzian
- Department of Anesthesiology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Ghahraman Mahmudi
- Hospital Management Research Centers, Department of Health Services Management, Sari Branch, Islamic Azad University, Sari, Iran
| | - Melody Omrani-Nava
- Department of Infectious Diseases, Sari Branch, Islamic Azad University, Sari, Iran
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55
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Activity of Gallium Meso- and Protoporphyrin IX against Biofilms of Multidrug-Resistant Acinetobacter baumannii Isolates. Pharmaceuticals (Basel) 2016; 9:ph9010016. [PMID: 26999163 PMCID: PMC4812380 DOI: 10.3390/ph9010016] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/12/2016] [Accepted: 03/15/2016] [Indexed: 11/17/2022] Open
Abstract
Acinetobacter baumannii is a challenging pathogen due to antimicrobial resistance and biofilm development. The role of iron in bacterial physiology has prompted the evaluation of iron-modulation as an antimicrobial strategy. The non-reducible iron analog gallium(III) nitrate, Ga(NO3)3, has been shown to inhibit A. baumannii planktonic growth; however, utilization of heme-iron by clinical isolates has been associated with development of tolerance. These observations prompted the evaluation of iron-heme sources on planktonic and biofilm growth, as well as antimicrobial activities of gallium meso- and protoporphyrin IX (Ga-MPIX and Ga-PPIX), metal heme derivatives against planktonic and biofilm bacteria of multidrug-resistant (MDR) clinical isolates of A. baumannii in vitro. Ga(NO3)3 was moderately effective at reducing planktonic bacteria (64 to 128 µM) with little activity against biofilms (≥512 µM). In contrast, Ga-MPIX and Ga-PPIX were highly active against planktonic bacteria (0.25 to 8 µM). Cytotoxic effects in human fibroblasts were observed following exposure to concentrations exceeding 128 µM of Ga-MPIX and Ga-PPIX. We observed that the gallium metal heme conjugates were more active against planktonic and biofilm bacteria, possibly due to utilization of heme-iron as demonstrated by the enhanced effects on bacterial growth and biofilm formation.
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56
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Shapiro JA, Wencewicz TA. Acinetobactin Isomerization Enables Adaptive Iron Acquisition in Acinetobacter baumannii through pH-Triggered Siderophore Swapping. ACS Infect Dis 2016; 2:157-68. [PMID: 27624967 DOI: 10.1021/acsinfecdis.5b00145] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pathogenic strains of Acinetobacter baumannii excrete multiple siderophores that enhance iron scavenging from host sources. The oxazoline siderophore pre-acinetobactin undergoes an unusual non-enzymatic isomerization, producing the isoxazolidinone acinetobactin. In this study, we explored the kinetics, mechanism, and biological consequence of this siderophore swapping. Pre-acinetobactin is excreted to the extracellular space where the isomerization to acinetobactin occurs with a pH-rate profile consistent with 5-exo-tet cyclization at C5' with clean stereochemical inversion. Pre-acinetobactin persists at pH <6, and acinetobactin is rapidly formed at pH >7, matching each siderophore's pH preference for iron(III) chelation and A. baumannii growth promotion. Acinetobactin isomerization provides two siderophores for the price of one, enabling A. baumannii to sequester iron over a broad pH range likely to be encountered during the course of an infection.
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Affiliation(s)
- Justin A. Shapiro
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
| | - Timothy A. Wencewicz
- Department of Chemistry, Washington University in St. Louis, One Brookings Drive, St. Louis, Missouri 63130, United States
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Medically Relevant Acinetobacter Species Require a Type II Secretion System and Specific Membrane-Associated Chaperones for the Export of Multiple Substrates and Full Virulence. PLoS Pathog 2016; 12:e1005391. [PMID: 26764912 PMCID: PMC4713064 DOI: 10.1371/journal.ppat.1005391] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 12/18/2015] [Indexed: 01/31/2023] Open
Abstract
Acinetobacter baumannii, A. nosocomialis, and A. pittii have recently emerged as opportunistic human pathogens capable of causing severe human disease; however, the molecular mechanisms employed by Acinetobacter to cause disease remain poorly understood. Many pathogenic members of the genus Acinetobacter contain genes predicted to encode proteins required for the biogenesis of a type II secretion system (T2SS), which have been shown to mediate virulence in many Gram-negative organisms. Here we demonstrate that Acinetobacter nosocomialis strain M2 produces a functional T2SS, which is required for full virulence in both the Galleria mellonella and murine pulmonary infection models. Importantly, this is the first bona fide secretion system shown to be required for virulence in Acinetobacter. Using bioinformatics, proteomics, and mutational analyses, we show that Acinetobacter employs its T2SS to export multiple substrates, including the lipases LipA and LipH as well as the protease CpaA. Furthermore, the Acinetobacter T2SS, which is found scattered amongst five distinct loci, does not contain a dedicated pseudopilin peptidase, but instead relies on the type IV prepilin peptidase, reinforcing the common ancestry of these two systems. Lastly, two of the three secreted proteins characterized in this study require specific chaperones for secretion. These chaperones contain an N-terminal transmembrane domain, are encoded adjacently to their cognate effector, and their disruption abolishes type II secretion of their cognate effector. Bioinformatic analysis identified putative chaperones located adjacent to multiple previously known type II effectors from several Gram-negative bacteria, which suggests that T2SS chaperones constitute a separate class of membrane-associated chaperones mediating type II secretion.
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58
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Dahdouh E, Orgaz B, Gómez-Gil R, Mingorance J, Daoud Z, Suarez M, San Jose C. Patterns of biofilm structure and formation kinetics among Acinetobacter baumannii clinical isolates with different antibiotic resistance profiles. MEDCHEMCOMM 2016. [DOI: 10.1039/c5md00377f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study evaluates the rates of biofilm formation in light of the different characteristics of twelve A. baumannii clinical isolates.
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Affiliation(s)
- E. Dahdouh
- Faculty of Veterinary
- Department of Animal Health
- University Complutense of Madrid
- Madrid
- Spain
| | - B. Orgaz
- Faculty of Veterinary
- Department of Food Science and Technology
- University Complutense of Madrid
- Madrid
- Spain
| | - R. Gómez-Gil
- Servicio de Microbiología
- Hospital Universitario La Paz
- IdiPAZ
- Madrid
- Spain
| | - J. Mingorance
- Servicio de Microbiología
- Hospital Universitario La Paz
- IdiPAZ
- Madrid
- Spain
| | - Z. Daoud
- Faculty of Medicine and Medical Sciences
- Department of Clinical Microbiology
- University of Balamand
- Amioun
- Lebanon
| | - M. Suarez
- Faculty of Veterinary
- Department of Animal Health
- University Complutense of Madrid
- Madrid
- Spain
| | - C. San Jose
- Faculty of Veterinary
- Department of Food Science and Technology
- University Complutense of Madrid
- Madrid
- Spain
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59
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Hasan T, Choi CH, Oh MH. Genes Involved in the Biosynthesis and Transport of Acinetobactin in Acinetobacter baumannii. Genomics Inform 2015; 13:2-6. [PMID: 25873846 PMCID: PMC4394237 DOI: 10.5808/gi.2015.13.1.2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 12/22/2014] [Accepted: 12/26/2014] [Indexed: 11/25/2022] Open
Abstract
Pathogenic bacteria survive in iron-limited host environments by using several iron acquisition mechanisms. Acinetobacter baumannii, causing serious infections in compromised patients, produces an iron-chelating molecule, called acinetobactin, which is composed of equimolar quantities of 2,3-dihydroxybenzoic acid (DHBA), L-threonine, and N-hydroxyhistamine, to compete with host cells for iron. Genes that are involved in the production and transport of acinetobactin are clustered within the genome of A. baumannii. A recent study showed that entA, located outside of the acinetobactin gene cluster, plays important roles in the biosynthesis of the acinetobactin precursor DHBA and in bacterial pathogenesis. Therefore, understanding the genes that are associated with the biosynthesis and transport of acinetobactin in the bacterial genome is required. This review is intended to provide a general overview of the genes in the genome of A. baumannii that are required for acinetobactin biosynthesis and transport.
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Affiliation(s)
- Tarik Hasan
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330-714, Korea
| | - Chul Hee Choi
- Department of Microbiology and Research Institute for Medical Sciences, Chungnam National University College of Medicine, Daejeon 301-747, Korea
| | - Man Hwan Oh
- Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330-714, Korea
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60
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Lin MF, Lan CY. Antimicrobial resistance in Acinetobacter baumannii: From bench to bedside. World J Clin Cases 2014; 2:787-814. [PMID: 25516853 PMCID: PMC4266826 DOI: 10.12998/wjcc.v2.i12.787] [Citation(s) in RCA: 212] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 08/25/2014] [Accepted: 10/27/2014] [Indexed: 02/05/2023] Open
Abstract
Acinetobacter baumannii (A. baumannii) is undoubtedly one of the most successful pathogens in the modern healthcare system. With invasive procedures, antibiotic use and immunocompromised hosts increasing in recent years, A. baumannii has become endemic in hospitals due to its versatile genetic machinery, which allows it to quickly evolve resistance factors, and to its remarkable ability to tolerate harsh environments. Infections and outbreaks caused by multidrug-resistant A. baumannii (MDRAB) are prevalent and have been reported worldwide over the past twenty or more years. To address this problem effectively, knowledge of species identification, typing methods, clinical manifestations, risk factors, and virulence factors is essential. The global epidemiology of MDRAB is monitored by persistent surveillance programs. Because few effective antibiotics are available, clinicians often face serious challenges when treating patients with MDRAB. Therefore, a deep understanding of the resistance mechanisms used by MDRAB can shed light on two possible strategies to combat the dissemination of antimicrobial resistance: stringent infection control and antibiotic treatments, of which colistin-based combination therapy is the mainstream strategy. However, due to the current unsatisfying therapeutic outcomes, there is a great need to develop and evaluate the efficacy of new antibiotics and to understand the role of other potential alternatives, such as antimicrobial peptides, in the treatment of MDRAB infections.
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61
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Kamoshida G, Kikuchi-Ueda T, Tansho-Nagakawa S, Nakano R, Nakano A, Kikuchi H, Ubagai T, Ono Y. Acinetobacter baumannii escape from neutrophil extracellular traps (NETs). J Infect Chemother 2014; 21:43-9. [PMID: 25287154 DOI: 10.1016/j.jiac.2014.08.032] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 08/28/2014] [Accepted: 08/29/2014] [Indexed: 01/09/2023]
Abstract
Acinetobacter baumannii and Pseudomonas aeruginosa are the same aerobic gram-negative bacillus and are usually harmless but cause infectious diseases in compromised hosts. Neutrophils play a critical role in infective protection against the extracellular growth of bacteria. Recently, a new biological defense mechanism called neutrophil extracellular traps (NETs) has been attracting attention. In present study, we investigated the responsiveness of neutrophils to A. baumannii and P. aeruginosa, focusing on NET formation. Neutrophils were co-cultured with A. baumannii or P. aeruginosa, and then DNA, histone and neutrophil elastase were stained, and the formation of NETs was evaluated. Neutrophils stimulated with A. baumannii had spread, but their shapes was maintained, and the nucleus was observed as clearly as that in non-stimulated neutrophils. However, neutrophils stimulated with P. aeruginosa did not maintain their cellular morphology, and the nucleus was disrupted with DNA, histones, and neutrophil elastase released into the extracellular space. These results suggest that A. baumannii does not induce NET formation, in contrast to P. aeruginosa. In addition, we measured expression of myeloperoxidase (MPO), reactive oxygen species (ROS) and superoxide in neutrophils, and we found that these expression in P. aeruginosa-stimulated neutrophils was stronger than that in A. baumannii-stimulated neutrophils. Furthermore, A. baumannii was not killed by neutrophils, in contrast to P. aeruginosa. In this study, we show that the reactivity of neutrophils and their biological defense mechanism are different between A. baumannii and P. aeruginosa, which is important for understanding the pathogenicity of these bacteria.
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Affiliation(s)
- Go Kamoshida
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
| | - Takane Kikuchi-Ueda
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
| | - Shigeru Tansho-Nagakawa
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
| | - Ryuichi Nakano
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
| | - Akiyo Nakano
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
| | - Hirotoshi Kikuchi
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
| | - Tsuneyuki Ubagai
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
| | - Yasuo Ono
- Department of Microbiology and Immunology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan
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Gentile V, Frangipani E, Bonchi C, Minandri F, Runci F, Visca P. Iron and Acinetobacter baumannii Biofilm Formation. Pathogens 2014; 3:704-19. [PMID: 25438019 PMCID: PMC4243436 DOI: 10.3390/pathogens3030704] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Revised: 08/09/2014] [Accepted: 08/12/2014] [Indexed: 01/19/2023] Open
Abstract
Acinetobacter baumannii is an emerging nosocomial pathogen, responsible for infection outbreaks worldwide. The pathogenicity of this bacterium is mainly due to its multidrug-resistance and ability to form biofilm on abiotic surfaces, which facilitate long-term persistence in the hospital setting. Given the crucial role of iron in A. baumannii nutrition and pathogenicity, iron metabolism has been considered as a possible target for chelation-based antibacterial chemotherapy. In this study, we investigated the effect of iron restriction on A. baumannii growth and biofilm formation using different iron chelators and culture conditions. We report substantial inter-strain variability and growth medium-dependence for biofilm formation by A. baumannii isolates from veterinary and clinical sources. Neither planktonic nor biofilm growth of A. baumannii was affected by exogenous chelators. Biofilm formation was either stimulated by iron or not responsive to iron in the majority of isolates tested, indicating that iron starvation is not sensed as an overall biofilm-inducing stimulus by A. baumannii. The impressive iron withholding capacity of this bacterium should be taken into account for future development of chelation-based antimicrobial and anti-biofilm therapies.
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Affiliation(s)
- Valentina Gentile
- Department of Sciences, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy.
| | - Emanuela Frangipani
- Department of Sciences, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy.
| | - Carlo Bonchi
- Department of Sciences, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy.
| | - Fabrizia Minandri
- Department of Sciences, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy.
| | - Federica Runci
- Department of Sciences, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy.
| | - Paolo Visca
- Department of Sciences, Roma Tre University, Viale Marconi 446, 00146 Rome, Italy.
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