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Kamani J, Nachum-Biala Y, Bukar L, Shand M, Harrus S. Molecular detection of Bartonella quintana, Acinetobacter baumannii and Acinetobacter haemolyticus in Pediculus humanus lice in Nigeria, West Africa. Zoonoses Public Health 2024; 71:48-59. [PMID: 37787179 DOI: 10.1111/zph.13082] [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: 04/02/2023] [Revised: 06/18/2023] [Accepted: 09/11/2023] [Indexed: 10/04/2023]
Abstract
The human lice Pediculus humanus is distributed worldwide but, it thrives and flourishes under conflict situations where people are forced to live in crowded unhygienic conditions. Molecular methods were used to identify and screen human lice for the DNA of pathogens of public health importance in an area that has been under insurgency related to religious and political conflicts with tens of thousands of internally displaced people (IDP). DNA of Bartonella quintana, Acinetobacter baumannii and Acinetobacter haemolyticus was detected in 18.3%, 40.0% and 1.7%, respectively, of human lice collected from children in Maiduguri, Nigeria. More body lice than head lice were positive for pathogen's DNA (64.3% vs. 44.4%; χ2 = 1.3, p = 0.33), but the difference was not significant. Two lice samples were found to harbour mixed DNA of B. quintana and A. baumannii. Phylogenetic analysis of the cytochrome b (cytb) gene sequences of the positive lice specimens placed them into clades A and E. This is the first report on the molecular identification of human lice and the detection of the DNA of pathogens of public health importance in lice in Nigeria, West Africa. The findings of this study will assist policy makers and medical practitioners in formulating a holistic healthcare delivery to IDPs.
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Affiliation(s)
- Joshua Kamani
- National Veterinary Research Institute (NVRI), Vom, Plateau State, Nigeria
| | - Yaarit Nachum-Biala
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Laminu Bukar
- National Veterinary Research Institute (NVRI), Vom, Plateau State, Nigeria
| | - Mike Shand
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK
| | - Shimon Harrus
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
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McDougal AN, DeMaet MA, Garcia B, York T, Iverson T, Ojo O, Patel J. A cluster investigation of Candida auris among hospitalized incarcerated patients. ANTIMICROBIAL STEWARDSHIP & HEALTHCARE EPIDEMIOLOGY : ASHE 2023; 3:e244. [PMID: 38156225 PMCID: PMC10753478 DOI: 10.1017/ash.2023.520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/15/2023] [Accepted: 11/15/2023] [Indexed: 12/30/2023]
Abstract
Objective Investigate and mitigate a cluster of Candida auris cases among incarcerated patients in a maximum-security prison hospital utilizing contact tracing, screening, whole genome sequencing, and environmental sampling and decontamination. Design Outbreak investigation. Setting Inpatient prison hospital affiliated with an academic tertiary referral center. Patients Inmates of the Texas Department of Criminal Justice. Methods Epidemiologic and environmental investigations were conducted including contact tracing, point prevalence surveys, and environmental sampling. Whole genome sequencing was performed on positive patient isolates. Results Following a clinical case of C. auris fungemia, 344 patients underwent C. auris surveillance screening. Eight (2.3%) patients were identified with C. auris colonization. All patients were male. Our index patient was the only clinical case and death. Whole genome sequencing was performed on the nine patient isolates. All isolates were clade III (Africa) and clustered together with the largest SNP difference being 21. Environmental cultures from 7 of 61 rooms (11.5%) were positive following terminal disinfection with bleach. Sites nearest to the patient were most often positive including the hospital bed rails and bedside table. The transmission cluster was successfully mitigated within 60 days of identification. Conclusions Implementation of an aggressive surveillance and decontamination program resulted in mitigation of a C. auris transmission cluster among our incarcerated patients. This investigation provides valuable insight into C. auris transmission in the incarcerated population, which is not considered a classic high-risk population as well as the challenges faced to stop transmission in a facility that requires the use of shared patient environments.
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Affiliation(s)
- April N. McDougal
- Department of Infection Control and Healthcare Epidemiology, University of Texas Medical Branch, Galveston, TX, USA
- Division of Infectious Disease, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA
| | - Mary Ann DeMaet
- Department of Infection Control and Healthcare Epidemiology, University of Texas Medical Branch, Galveston, TX, USA
| | - Bobbiejean Garcia
- Healthcare Safety Unit, Texas Department of State Health Services, Austin, TX, USA
| | - Teresa York
- Department of Infection Control and Healthcare Epidemiology, University of Texas Medical Branch, Galveston, TX, USA
| | - Thomas Iverson
- Utah Department of Health and Human Services, Salt Lake City, UT, USA
| | - Olugbenga Ojo
- Division of General Internal Medicine, Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX, USA
- Texas Department of Criminal Justice Hospital & Clinics, Galveston, TX, USA
| | - Janak Patel
- Department of Infection Control and Healthcare Epidemiology, University of Texas Medical Branch, Galveston, TX, USA
- Division of Infectious Disease, Department of Pediatrics, University of Texas Medical Branch, Galveston, TX, USA
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Plasencia-Rebata S, Levy-Blitchtein S, Del Valle-Mendoza J, Silva-Caso W, Peña-Tuesta I, Vicente Taboada W, Barreda Bolaños F, Aguilar-Luis MA. Effect of Phenylalanine-Arginine Beta-Naphthylamide on the Values of Minimum Inhibitory Concentration of Quinolones and Aminoglycosides in Clinical Isolates of Acinetobacter baumannii. Antibiotics (Basel) 2023; 12:1071. [PMID: 37370390 DOI: 10.3390/antibiotics12061071] [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: 04/16/2023] [Revised: 06/06/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023] Open
Abstract
(1) Background: Acinetobacter baumannii has become the most important pathogen responsible for nosocomial infections in health systems. It expresses several resistance mechanisms, including the production of β-lactamases, changes in the cell membrane, and the expression of efflux pumps. (2) Methods: A. baumannii was detected by PCR amplification of the blaOXA-51-like gene. Antimicrobial susceptibility to fluoroquinolones and aminoglycosides was assessed using the broth microdilution technique according to 2018 CLSI guidelines. Efflux pump system activity was assessed by the addition of a phenylalanine-arginine beta-naphthylamide (PAβN) inhibitor. (3) Results: A total of nineteen A. baumannii clinical isolates were included in the study. In an overall analysis, in the presence of PAβN, amikacin susceptibility rates changed from 84.2% to 100%; regarding tobramycin, they changed from 68.4% to 84.2%; for nalidixic acid, they changed from 73.7% to 79.0%; as per ciprofloxacin, they changed from 68.4% to 73.7%; and, for levofloxacin, they stayed as 79.0% in both groups. (4) Conclusions: The addition of PAβN demonstrated a decrease in the rates of resistance to antimicrobials from the family of quinolones and aminoglycosides. Efflux pumps play an important role in the emergence of multidrug-resistant A. baumannii strains, and their inhibition may be useful as adjunctive therapy against this pathogen.
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Affiliation(s)
- Stefany Plasencia-Rebata
- Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
| | - Saul Levy-Blitchtein
- Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Microbiology Department, Vall d'Hebron University Hospital, 08034 Barcelona, Spain
| | - Juana Del Valle-Mendoza
- Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Laboratorio de Biomedicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Instituto de Investigación Nutricional, Lima 15024, Peru
| | - Wilmer Silva-Caso
- Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Laboratorio de Biomedicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Instituto de Investigación Nutricional, Lima 15024, Peru
| | - Isaac Peña-Tuesta
- Laboratorio de Biomedicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Instituto de Investigación Nutricional, Lima 15024, Peru
| | | | | | - Miguel Angel Aguilar-Luis
- Escuela de Medicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Laboratorio de Biomedicina, Facultad de Ciencias de la Salud, Universidad Peruana de Ciencias Aplicadas, Lima 15023, Peru
- Instituto de Investigación Nutricional, Lima 15024, Peru
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Vaccination with a combination of planktonic and biofilm virulence factors confers protection against carbapenem-resistant Acinetobacter baumannii strains. Sci Rep 2022; 12:19909. [PMID: 36402866 PMCID: PMC9675771 DOI: 10.1038/s41598-022-24163-z] [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: 08/02/2022] [Accepted: 11/10/2022] [Indexed: 11/21/2022] Open
Abstract
Acinetobacter baumannii is a multi-drug resistant pathogen with the ability to switch between planktonic and biofilm phenotypes. Although there is no vaccine against A. baumannii infections, many attempts have been made to develop vaccines using planktonic or biofilm antigens. To cover the different phenotypes of A. baumannii during growth and attachment, we combined planktonic upregulated antigens of iron receptors with biofilm upregulated antigens of pilus rods and evaluated immune responses and protective efficacies of the combined vaccine using lethal and sub-lethal murine sepsis models. The results showed that the combined vaccine elicited high IgG antibody titers and conferred protection against lethal doses of two Carbapenem-resistant high adherent A. baumannii strains. Complete bacterial clearance from all the affected tissues of the mice challenged with A. baumannii was an excellent achievement with our quadrivalent immunogen. These results demonstrate both planktonic and biofilm antigens are important during antigen selection for vaccine design.
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Tawfick MM, Rady HF, El-Borhamy MI, Maraqa AD. Dissemination of Plasmid-Mediated Aminoglycoside-Modifying Enzymes Among MDR Acinetobacter baumannii Isolates from a Tertiary Care Egyptian Hospital. Open Microbiol J 2020. [DOI: 10.2174/1874285802014010098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background:
Acinetobacter baumannii is one of the most challenging multidrug-resistant (MDR) nosocomial pathogens worldwide. Aminoglycosides are used for the treatment of A. baumannii infections, however, resistance to aminoglycosides is currently emerging, limiting therapeutic choices.
Objective:
In this study, the prevalence of aminoglycoside resistance and plasmid-mediated mechanisms of aminoglycoside resistance were investigated in A. baumannii clinical isolates collected from ICU patients at a tertiary care hospital in Egypt.
Methods:
The automated Vitek 2 system was used to identify A. baumannii species and determination of the antimicrobial susceptibility pattern. The identification of A. baumannii was confirmed by the detection of the blaOXA-51-like gene intrinsic to this species. Minimum Inhibitory Concentration (MIC) of gentamicin was determined using E-test following the CLSI breakpoints. Isolates were screened for the prevalence and diversity of the plasmid-carried aminoglycoside-modifying enzymes encoding genes aacC1, aadA1, aadB and aphA6. For genetic diversity analysis, the ERIC-PCR method was performed.
Results:
All A. baumannii isolates were MDR with high resistance rates to tested antimicrobials. The resistance rate to gentamicin was 92.9% with elevated MICs (≥ 32 μg/mL). The gentamicin-resistant isolates harboured one or more of the studied genes with the prevalence of aphA6 (81%). ERIC-based genotyping revealed that there was no evidence of A. baumannii clonal dissemination among isolates.
Conclusion:
The study concluded that MDR A. baumannii isolates were highly resistant to gentamicin. The plasmid-carried aminoglycoside-modifying enzymes encoding genes were disseminated among isolates with the AphA6 gene, which was the most prevalent one. The acquisition of more than one aminoglycoside resistance gene was associated with an elevated MIC of gentamicin. Thus, regular surveillance studies of the emerging resistance to antimicrobials and strict measures to control the dissemination of resistance determinants genes are warranted.
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Ranjbar R, Tolon SS, Zayeri S, Sami M. The Frequency of Antibiotic Resistance and ESBLs Among Clinically Acinetobacter baumannii Strains Isolated from Patients in a Major Hospital in Tehran, Iran. Open Microbiol J 2018; 12:254-260. [PMID: 30197699 PMCID: PMC6110056 DOI: 10.2174/1874285801812010254] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 07/10/2018] [Accepted: 07/14/2018] [Indexed: 02/06/2023] Open
Abstract
Background: Bacterial resistance to antibiotics limits treatment options, increases morbidity and mortality, and raises the risk of antibiotic-associated adverse events. Antibacterial resistance emerges rapidly following an increase in the consumption of antibiotics against infectious diseases. The spread of ESBL producing strains has a limiting factor based on antibiotic function for the treatment of infections particularly caused by Acinetobacter baumannii (A. baumannii). Objective: This study was conducted to evaluate the prevalence of antimicrobial resistance and distribution of blaTEM, blaCTX, and blaSHV genes among A. baumannii strains isolated from clinical samples at a major hospital in Teheran, Iran. Methods: A. baumannii strains were isolated and identified using standard microbiological methods. The disc diffusion and combined discs methods were used for testing antimicrobial susceptibility and to identify the strains producing Extended-Spectrum Beta-Lactamases (ESBL), respectively. DNA extraction was done by boiling method. Finally, the frequency of resistant genes including blaTEM, blaCTX, and blaSHV in ESBL producing isolates was studied by PCR. Results: Gender distribution in this study was 53 (53%) samples for men and 47 (47%) for women. Totally, one hundred A. baumannii strains were isolated. More than 93% of the isolates were multi drug resistant. The highest to lowest antibiotic resistance was observed against amoxicillin/clavulanic acid (98%), ceftriaxone (96%), cefotaxime (94%), and ceftazidime (93%), respectively. The frequency of positive phenotypic test of ESBL was 19% and 16% for CAZ-C and CTX-C, respectively. The frequency of blaTEM, blaCTX, and blaSHV genes was 52.1, 43.4, and 21.7, respectively. Conclusion: A. baumannii isolates exhibited an extremely worrying level of antibiotic resistance, and a high percentage of the isolates showed MDR in this study. This is a serious warning because ESBLs are a major threat to the effectiveness of antibiotics that are currently available for medical uses. The frequency of genes encoded ESBL isolates of A. baumannii may be due to overuse and misuse of antibiotics.
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Affiliation(s)
- Reza Ranjbar
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Sajjad S Tolon
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Shahin Zayeri
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Mehrdad Sami
- Department of Clinical Sciences, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran
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Fernando DM, Khan IUH, Patidar R, Lapen DR, Talbot G, Topp E, Kumar A. Isolation and Characterization of Acinetobacter baumannii Recovered from Campylobacter Selective Medium. Front Microbiol 2016; 7:1871. [PMID: 27917170 PMCID: PMC5114274 DOI: 10.3389/fmicb.2016.01871] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/07/2016] [Indexed: 11/29/2022] Open
Abstract
Acinetobacter baumannii, a Gram-negative opportunistic pathogen, is known to cause multidrug resistant infections. This organism has primarily been isolated from clinical environments and its environmental reservoirs remain largely unknown. In the present study, we recovered seven isolates of A. baumannii growing under conditions selective for Campylobacter spp. (microaerophilic at 42°C and in the presence of antibiotics) from dairy cattle manure storage tank or surface water impacted by livestock effluents. Antibiotic susceptibility tests revealed that all of these isolates were less susceptible to at least two different clinically relevant antibiotics, compared to the type strain A. baumannii ATCC17978. Expression of resistance-nodulation-division efflux pumps, an important mechanism of intrinsic resistance in these organisms, was analyzed, and adeB was found to be overexpressed in one and adeJ was overexpressed in three isolates. Comparison of these isolates using genomic DNA Macro-Restriction Fragment Pattern Analysis (MRFPA) revealed relatively low relatedness among themselves or with some of the clinical isolates from previous studies. This study suggests that A. baumannii isolates are capable of growing under selective conditions for Campylobacter spp. and that this organism can be present in manure and water.
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Affiliation(s)
- Dinesh M Fernando
- Department of Microbiology, University of Manitoba , Winnipeg, MB, Canada
| | - Izhar U H Khan
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada , Ottawa, ON, Canada
| | - Rakesh Patidar
- Department of Microbiology, University of Manitoba , Winnipeg, MB, Canada
| | - David R Lapen
- Ottawa Research and Development Centre, Agriculture and Agri-Food Canada , Ottawa, ON, Canada
| | - Guylaine Talbot
- Sherbrooke Research and Development Centre, Agriculture and Agri-Food Canada , Sherbrooke, QC, Canada
| | - Edward Topp
- London Research and Development Centre, Agriculture and Agri-Food Canada , London, ON, Canada
| | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada; Department of Medical Microbiology, University of Manitoba, Winnipeg, MB, Canada
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Chatterjee S, Datta S, Roy S, Ramanan L, Saha A, Viswanathan R, Som T, Basu S. Carbapenem Resistance in Acinetobacter baumannii and Other Acinetobacter spp. Causing Neonatal Sepsis: Focus on NDM-1 and Its Linkage to ISAba125. Front Microbiol 2016; 7:1126. [PMID: 27551277 PMCID: PMC4976090 DOI: 10.3389/fmicb.2016.01126] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 07/06/2016] [Indexed: 11/13/2022] Open
Abstract
Carbapenem-resistant determinants and their surrounding genetic structure were studied in Acinetobacter spp. from neonatal sepsis cases collected over 7 years at a tertiary care hospital. Acinetobacter spp. (n = 68) were identified by ARDRA followed by susceptibility tests. Oxacillinases, metallo-β-lactamases (MBLs), extended-spectrum β-lactamases and AmpCs, were detected phenotypically and/or by PCR followed by DNA sequencing. Transconjugants possessing the bla NDM-1(New Delhi metallo-β-lactamase) underwent further analysis for plasmids, integrons and associated genes. Genetic environment of the carbapenemases were studied by PCR mapping and DNA sequencing. Multivariate logistic regression was used to identify risk factors for sepsis caused by NDM-1-harboring organisms. A. baumannii (72%) was the predominant species followed by A. calcoaceticus (10%), A. lwoffii (6%), A. nosocomialis (3%), A. junni (3%), A. variabilis (3%), A. haemolyticus (2%), and 14TU (2%). Fifty six percent of the isolates were meropenem-resistant. Oxacillinases present were OXA-23-like, OXA-58-like and OXA-51-like, predominately in A. baumannii. NDM-1 was the dominant MBL (22%) across different Acinetobacter spp. Isolates harboring NDM-1 also possessed bla (VIM-2, PER-1, VEB-2, CTX-M-15), armA, aac(6')Ib, aac(6')Ib-cr genes. bla NDM-1was organized in a composite transposon between two copies of ISAba125 in the isolates irrespective of the species. Further, OXA-23-like gene and OXA-58-like genes were linked with ISAba1 and ISAba3 respectively. Isolates were clonally diverse. Integrons were variable in sequence but not associated with carbapenem resistance. Most commonly found genes in the 5' and 3'conserved segment were aminoglycoside resistance genes (aadB, aadA2, aac4'), non-enzymatic chloramphenicol resistance gene (cmlA1g) and ADP-ribosylation genes (arr2, arr3). Outborn neonates had a significantly higher incidence of sepsis due to NDM-1 harboring isolates than their inborn counterparts. This study demonstrates the significance of both A. baumannii and other species of Acinetobacter in cases of neonatal sepsis over an extended period. Oxacillinases and bla NDM-1 are the major contributors to carbapenem resistance. The dissemination of the bla NDM-1 is likely linked to Tn125 in diverse clones of the isolates.
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Affiliation(s)
- Somdatta Chatterjee
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases Kolkata, India
| | - Saswati Datta
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases Kolkata, India
| | - Subhasree Roy
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases Kolkata, India
| | - Lavanya Ramanan
- Absolut Data Labs, Absolut Data Research and Analytics Gurgaon, India
| | - Anindya Saha
- Department of Neonatology, Institute of Postgraduate Medical Education and Research, SSKM Hospital Kolkata, India
| | - Rajlakshmi Viswanathan
- Department of Neonatology, Institute of Postgraduate Medical Education and Research, SSKM Hospital Kolkata, India
| | - Tapas Som
- Department of Neonatology, Institute of Postgraduate Medical Education and Research, SSKM Hospital Kolkata, India
| | - Sulagna Basu
- Division of Bacteriology, National Institute of Cholera and Enteric Diseases Kolkata, India
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Molecular characterization and antimicrobial susceptibility of Acinetobacter baumannii isolates obtained from two hospital outbreaks in Los Angeles County, California, USA. BMC Infect Dis 2016; 16:194. [PMID: 27146090 PMCID: PMC4857389 DOI: 10.1186/s12879-016-1526-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 04/27/2016] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Antibiotic resistant strains of Acinetobacter baumannii have been responsible for an increasing number of nosocomial infections including bacteremia and ventilator-associated pneumonia. In this study, we analyzed 38 isolates of A. baumannii obtained from two hospital outbreaks in Los Angeles County for the molecular epidemiology, antimicrobial susceptibility and resistance determinants. METHODS Pulsed field gel electrophoresis, tri-locus multiplex PCR and multi-locus sequence typing (Pasteur scheme) were used to examine clonal relationships of the outbreak isolates. Broth microdilution method was used to determine antimicrobial susceptibility of these isolates. PCR and subsequent DNA sequencing were employed to characterize antibiotic resistance genetic determinants. RESULTS Trilocus multiplex PCR showed these isolates belong to Global Clones I and II, which were confirmed to ST1 and ST2, respectively, by multi-locus sequence typing. Pulsed field gel electrophoresis analysis identified two clonal clusters, one with 20 isolates (Global Clone I) and the other with nine (Global Clone II), which dominated the two outbreaks. Antimicrobial susceptibility testing using 14 antibiotics indicated that all isolates were resistant to antibiotics belonging to four or more categories of antimicrobial agents. In particular, over three fourth of 38 isolates were found to be resistant to both imipenem and meropenem. Additionally, all isolates were found to be resistant to piperacillin, four cephalosporin antibiotics, ciprofloxacin and levofloxacin. Resistance phenotypes of these strains to fluoroquinolones were correlated with point mutations in gyrA and parC genes that render reduced affinity to target proteins. ISAba1 was detected immediately upstream of the bla OXA-23 gene present in those isolates that were found to be resistant to both carbapenems. Class 1 integron-associated resistance gene cassettes appear to contribute to resistance to aminoglycoside antibiotics. CONCLUSION The two outbreaks were found to be dominated by two clonal clusters of A. baumannii belonging to MLST ST1 and ST2. All isolates were resistant to antibiotics of at least four categories of antimicrobial agents, and their antimicrobial susceptibility profiles correlate well with genetic determinants. The results of this study will facilitate our understanding of the molecular epidemiology, antimicrobial susceptibility and mechanisms of resistance of A. baumannii obtained from Los Angeles hospitals.
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Li P, Niu W, Li H, Lei H, Liu W, Zhao X, Guo L, Zou D, Yuan X, Liu H, Yuan J, Bai C. Rapid detection of Acinetobacter baumannii and molecular epidemiology of carbapenem-resistant A. baumannii in two comprehensive hospitals of Beijing, China. Front Microbiol 2015; 6:997. [PMID: 26441924 PMCID: PMC4585070 DOI: 10.3389/fmicb.2015.00997] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/07/2015] [Indexed: 12/21/2022] Open
Abstract
Acinetobacter baumannii is an important opportunistic pathogen associated with a variety of nosocomial infections. A rapid and sensitive molecular detection in clinical isolates is quite needed for the appropriate therapy and outbreak control of A. baumannii. Group 2 carbapenems have been considered the agents of choice for the treatment of multiple drug-resistant A. baumannii. But the prevalence of carbapenem-resistant A. baumannii (CRAB) has been steadily increasing in recent years. Here, we developed a loop-mediated isothermal amplification (LAMP) assay for the rapid detection of A. baumannii in clinical samples by using high-specificity primers of the bla OXA-51 gene. Then we investigated the OXA-carbapenemases molecular epidemiology of A. baumannii isolates in two comprehensive hospitals in Beijing. The results showed that the LAMP assay could detect target DNA within 60 min at 65°C. The detection limit was 50 pg/μl, which was about 10-fold greater than that of PCR. Furthermore, this method could distinguish A. baumannii from the homologous A. nosocomialis and A. pittii. A total of 228 positive isolates were identified by this LAMP-based method for A. baumannii from 335 intensive care unit patients with clinically suspected multi-resistant infections in two hospitals in Beijing. The rates of CRAB are on the rise and are slowly becoming a routine phenotype for A. baumannii. Among the CRABs, 92.3% harbored both the bla OXA-23 and bla OXA-51 genes. Thirty-three pulsotypes were identified by pulsed-field gel electrophoresis, and the majority belonged to clone C. In conclusion, the LAMP method developed for detecting A. baumannii was faster and simpler than conventional PCR and has great potential for both point-of-care testing and basic research. We further demonstrated a high distribution of class D carbapenemase-encoding genes, mainly OXA-23, which presents an emerging threat in hospitals in China.
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Affiliation(s)
- Puyuan Li
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Wenkai Niu
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Huan Li
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Hong Lei
- Department of Clinical Laboratory, 309th Hospital of Chinese People's Liberation Army Beijing, China
| | - Wei Liu
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Xiangna Zhao
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Leijing Guo
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Dayang Zou
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Xin Yuan
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Huiying Liu
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Jing Yuan
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Changqing Bai
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
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Khosravi AD, Sadeghi P, Shahraki AH, Heidarieh P, Sheikhi N. Molecular Methods for Identification of Acinetobacter Species by Partial Sequencing of the rpoB and 16S rRNA Genes. J Clin Diagn Res 2015; 9:DC09-13. [PMID: 26393127 DOI: 10.7860/jcdr/2015/13867.6188] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/04/2015] [Indexed: 11/24/2022]
Abstract
BACKGROUND Acinetobacter spp. is a diverse group of Gram-negative bacteria which are ubiquitous in soil and water, and an important cause of nosocomial infections. The purpose of this study was to identify a collection of Acinetobacter spp. clinical isolates accurately and to investigate their antibiotic susceptibility patterns. MATERIALS AND METHODS A total of 197 non-duplicate clinical isolates of Acinetobacter spp. isolates identified using conventional biochemical tests. The molecular technique of PCR-RFLP and sequence analysis of rpoB and 16S rRNA genes was applied for species identification. Antimicrobial susceptibility test was performed with a disk diffusion assay. RESULTS Based on 16S rRNA and rpoB genes analysis separately, most of clinical isolates can be identified with high bootstrap values. However, the identity of the isolate 555T was uncertain due to high similarity of A. grimontii and A. junii. Identification by concatenation of 16S rRNA and rpoB confirmed the identity of clinical isolates of Acenitobacer to species level confidently. Accordingly, the isolate 555T assigned as A. grimontii due to 100% similarity to A. grimontii. Moreover, this isolate showed 98.64% to A. junii. Besides, the identity of the isolates 218T and 364T was confirmed as Genomic species 3 and A. calcoaceticus respectively. So, the majority of Acinetobacter spp. isolates, were identified as: A. baumannii (131 isolates, 66%), A. calcoaceticus (9 isolates, 4.5%), and A. genomosp 16 (8 isolates, 4%). The rest of identified species showed the lower frequencies. In susceptibility test, 105 isolates (53%), presented high antibiotic resistance of 90% to ceftriaxone, piperacillin, piperacillin tazobactam, amikacin, and 81% to ciprofloxacin. CONCLUSION Sequence analysis of the 16S rRNA and rpoB spacer simultaneously was able to do identification of Acinetobacter spp. to species level. A.baumannii was identified as the most prevalent species with high antibiotic resistance. Other species showed lower frequencies ranged from 4 to 9 strains.
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Affiliation(s)
- Azar Dokht Khosravi
- Professor, Department of Microbiology & Health Research Institute, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences , Ahvaz, Iran
| | - Parisa Sadeghi
- Research Assistant, Department of Microbiology, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences , Ahvaz, Iran; Clinical Biochemistry Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran
| | - Abdolrazagh Hashemi Shahraki
- Assistant Professor, Department of Health Research Institute, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences , Ahvaz, Iran; Department of Epidemiology, Pasteur Institute of Iran
| | - Parvin Heidarieh
- Assistant Professor, Department of Bacteriology and Virology, Alborz University of Medical Sciences , Karaj, Iran
| | - Nasrin Sheikhi
- Research Assistant, Department of Microbiology Unit, Masoud Medical Laboratory , Tehran, Iran
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Li XZ, Plésiat P, Nikaido H. The challenge of efflux-mediated antibiotic resistance in Gram-negative bacteria. Clin Microbiol Rev 2015; 28:337-418. [PMID: 25788514 PMCID: PMC4402952 DOI: 10.1128/cmr.00117-14] [Citation(s) in RCA: 899] [Impact Index Per Article: 99.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The global emergence of multidrug-resistant Gram-negative bacteria is a growing threat to antibiotic therapy. The chromosomally encoded drug efflux mechanisms that are ubiquitous in these bacteria greatly contribute to antibiotic resistance and present a major challenge for antibiotic development. Multidrug pumps, particularly those represented by the clinically relevant AcrAB-TolC and Mex pumps of the resistance-nodulation-division (RND) superfamily, not only mediate intrinsic and acquired multidrug resistance (MDR) but also are involved in other functions, including the bacterial stress response and pathogenicity. Additionally, efflux pumps interact synergistically with other resistance mechanisms (e.g., with the outer membrane permeability barrier) to increase resistance levels. Since the discovery of RND pumps in the early 1990s, remarkable scientific and technological advances have allowed for an in-depth understanding of the structural and biochemical basis, substrate profiles, molecular regulation, and inhibition of MDR pumps. However, the development of clinically useful efflux pump inhibitors and/or new antibiotics that can bypass pump effects continues to be a challenge. Plasmid-borne efflux pump genes (including those for RND pumps) have increasingly been identified. This article highlights the recent progress obtained for organisms of clinical significance, together with methodological considerations for the characterization of MDR pumps.
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Affiliation(s)
- Xian-Zhi Li
- Human Safety Division, Veterinary Drugs Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
| | - Patrick Plésiat
- Laboratoire de Bactériologie, Faculté de Médecine-Pharmacie, Centre Hospitalier Régional Universitaire, Université de Franche-Comté, Besançon, France
| | - Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, California, USA
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13
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Insertions or deletions (Indels) in the rrn 16S-23S rRNA gene internal transcribed spacer region (ITS) compromise the typing and identification of strains within the Acinetobacter calcoaceticus-baumannii (Acb) complex and closely related members. PLoS One 2014; 9:e105390. [PMID: 25141005 PMCID: PMC4139376 DOI: 10.1371/journal.pone.0105390] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 07/17/2014] [Indexed: 11/19/2022] Open
Abstract
To determine whether ITS sequences in the rrn operon are suitable for identifying individual Acinetobacter Acb complex members, we analysed length and sequence differences between multiple ITS copies within the genomes of individual strains. Length differences in ITS reported previously between A. nosocomialis BCRC15417T (615 bp) and other strains (607 bp) can be explained by presence of an insertion (indel 13i/1) in the longer ITS variant. The same Indel 13i/1 was also found in ITS sequences of ten strains of A. calcoaceticus, all 639 bp long, and the 628 bp ITS of Acinetobacter strain BENAB127. Four additional indels (13i/2–13i/5) were detected in Acinetobacter strain c/t13TU 10090 ITS length variants (608, 609, 620, 621 and 630 bp). These ITS variants appear to have resulted from horizontal gene transfer involving other Acinetobacter species or in some cases unrelated bacteria. Although some ITS copies in strain c/t13TU 10090 are of the same length (620 bp) as those in Acinetobacter strains b/n1&3, A. pittii (10 strains), A. calcoaceticus and A. oleivorans (not currently acknowledged as an Acb member), their individual ITS sequences differ. Thus ITS length by itself can not by itself be used to identify Acb complex strains. A shared indel in ITS copies in two separate Acinetobacter species compromises the specificity of ITS targeted probes, as shown with the Aun-3 probe designed to target the ITS in A. pitti. The presence of indel 13i/5 in the ITS of Acinetobacter strain c/t13TU means it too responded positively to this probe. Thus, neither ITS sequencing nor the currently available ITS targeted probes can distinguish reliably between Acb member species.
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Al-Anazi KA, Al-Jasser AM. Infections Caused by Acinetobacter baumannii in Recipients of Hematopoietic Stem Cell Transplantation. Front Oncol 2014; 4:186. [PMID: 25072028 PMCID: PMC4095644 DOI: 10.3389/fonc.2014.00186] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 07/02/2014] [Indexed: 01/21/2023] Open
Abstract
Acinetobacter baumannii (A. baumannii) is a Gram-negative, strictly aerobic, non-fermentative coccobacillus, which is widely distributed in nature. Recently, it has emerged as a major cause of health care-associated infections (HCAIs) in addition to its capacity to cause community-acquired infections. Risk factors for A. baumannii infections and bacteremia in recipients of hematopoietic stem cell transplantation include: severe underlying illness such as hematological malignancy, prolonged use of broad-spectrum antibiotics, invasive instrumentation such as central venous catheters or endotracheal intubation, colonization of respiratory, gastrointestinal, or urinary tracts in addition to severe immunosuppression caused by using corticosteroids for treating graft versus host disease. The organism causes a wide spectrum of clinical manifestations, but serious complications such as bacteremia, septic shock, ventilator-associated pneumonia, extensive soft tissue necrosis, and rapidly progressive systemic infections that ultimately lead to multi-organ failure and death are prone to occur in severely immunocompromised hosts. The organism is usually resistant to many antimicrobials including penicillins, cephalosporins, trimethoprim-sulfamethoxazole, almost all fluoroquinolones, and most of the aminoglycosides. The recently increasing resistance to carbapenems, colistin, and polymyxins is alarming. Additionally, there are geographic variations in the resistance patterns and several globally and regionally resistant strains have already been described. Successful management of A. baumannii infections depends upon appropriate utilization of antibiotics and strict application of preventive and infection control measures. In uncomplicated infections, the use of a single active beta-lactam may be justified, while definitive treatment of complicated infections in critically ill individuals may require drug combinations such as colistin and rifampicin or colistin and carbapenem. Mortality rates in patients having bacteremia or septic shock may reach 70%. Good prognosis is associated with presence of local infection, absence of multidrug resistant strain, and presence of uncomplicated infection while poor outcome is associated with severe underlying medical illness, bacteremia, septic shock, multi-organ failure, HCAIs, admission to intensive care facilities for higher levels of care, and culture of certain aggressive genotypes of A. baumannii.
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Affiliation(s)
- Khalid Ahmed Al-Anazi
- Section of Adult Hematology and Oncology, Department of Medicine, College of Medicine and King Khalid University Hospital, King Saud University, Riyadh, Saudi Arabia
| | - Asma M. Al-Jasser
- Central Regional Laboratory, Ministry of Health, Riyadh, Saudi Arabia
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15
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Sung JY, Koo SH, Kim S, Kwon KC. Epidemiological characterizations of class 1 integrons from multidrug-resistant acinetobacter isolates in Daejeon, Korea. Ann Lab Med 2014; 34:293-9. [PMID: 24982834 PMCID: PMC4071186 DOI: 10.3343/alm.2014.34.4.293] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 10/09/2013] [Accepted: 05/01/2014] [Indexed: 01/19/2023] Open
Abstract
Background Multidrug-resistant (MDR) Acinetobacter spp. acquire antimicrobial agent-resistance genes via class 1 integrons. In this study, integrons were characterized to investigate the antimicrobial resistance mechanisms of MDR Acinetobacter isolates. In addition, the relationship between the integron type and integron-harboring bacterial species was analyzed by using epidemiological typing methods. Methods Fifty-six MDR Acinetobacter spp.-A. baumannii (N=30), A. bereziniae (N=4), A. nosocomialis (N=5), and A. pittii (N=17)-were isolated. The minimum inhibitory concentrations (MICs) were determined on the basis of the results of the Epsilometer test (Etest). PCR and DNA sequencing was performed to characterize the gene cassette arrays of class 1 integrons. Multilocus sequence typing (MLST) and repetitive extragenic palindromic sequence (REP)-PCR were performed for epidemiological typing. Results Class 1 integrons were detected in 50 (89.3%) of the 56 isolates, but no class 2 or 3 integron was found within the cohorts. The class 1 integrons were classified into 4 types: 2.3-kb type A (aacA4-catB8-aadA1), 3.0-kb type B (aacA4-blaIMP-1-blaOXA-2), 3.0-kb type C (blaVIM-2-aacA7-aadA1), and 1.8-kb type D (aac3-1-blaOXA-2-orfD). Type A was most prevalent and was detected only in A. baumannii isolates, except for one A. bereziniae isolate; however, type B was amplified in all Acinetobacter isolates except for A. baumannii isolates, regardless of clone and separation time of the bacteria. Conclusions Although class 1 integron can be transferred horizontally between unrelated isolates belonging to different species, certain types of class 1 integrons tend to transfer horizontally and vertically among A. baumannii or non-baumannii Acinetobacter isolates.
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Affiliation(s)
- Ji Youn Sung
- Department of Biomedical Laboratory Science, Far East University, Eumseong, Korea
| | - Sun Hoe Koo
- Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea
| | - Semi Kim
- Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea
| | - Kye Chul Kwon
- Department of Laboratory Medicine, College of Medicine, Chungnam National University, Daejeon, Korea
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Mustaev A, Malik M, Zhao X, Kurepina N, Luan G, Oppegard LM, Hiasa H, Marks KR, Kerns RJ, Berger JM, Drlica K. Fluoroquinolone-gyrase-DNA complexes: two modes of drug binding. J Biol Chem 2014; 289:12300-12. [PMID: 24497635 DOI: 10.1074/jbc.m113.529164] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA gyrase and topoisomerase IV control bacterial DNA topology by breaking DNA, passing duplex DNA through the break, and then resealing the break. This process is subject to reversible corruption by fluoroquinolones, antibacterials that form drug-enzyme-DNA complexes in which the DNA is broken. The complexes, called cleaved complexes because of the presence of DNA breaks, have been crystallized and found to have the fluoroquinolone C-7 ring system facing the GyrB/ParE subunits. As expected from x-ray crystallography, a thiol-reactive, C-7-modified chloroacetyl derivative of ciprofloxacin (Cip-AcCl) formed cross-linked cleaved complexes with mutant GyrB-Cys(466) gyrase as evidenced by resistance to reversal by both EDTA and thermal treatments. Surprisingly, cross-linking was also readily seen with complexes formed by mutant GyrA-G81C gyrase, thereby revealing a novel drug-gyrase interaction not observed in crystal structures. The cross-link between fluoroquinolone and GyrA-G81C gyrase correlated with exceptional bacteriostatic activity for Cip-AcCl with a quinolone-resistant GyrA-G81C variant of Escherichia coli and its Mycobacterium smegmatis equivalent (GyrA-G89C). Cip-AcCl-mediated, irreversible inhibition of DNA replication provided further evidence for a GyrA-drug cross-link. Collectively these data establish the existence of interactions between the fluoroquinolone C-7 ring and both GyrA and GyrB. Because the GyrA-Gly(81) and GyrB-Glu(466) residues are far apart (17 Å) in the crystal structure of cleaved complexes, two modes of quinolone binding must exist. The presence of two binding modes raises the possibility that multiple quinolone-enzyme-DNA complexes can form, a discovery that opens new avenues for exploring and exploiting relationships between drug structure and activity with type II DNA topoisomerases.
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Affiliation(s)
- Arkady Mustaev
- From the Public Health Research Institute and Department of Microbiology and Molecular Genetics, New Jersey Medical School, Rutgers Biomedical and Health Sciences, Newark, New Jersey 07103
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Lopes BS, Gould IM, Opazo AF, Amyes SGB. The resistance profile of Acinetobacter baumannii strains isolated from the Aberdeen Royal Infirmary. Int J Antimicrob Agents 2012; 39:361-2. [PMID: 22325121 DOI: 10.1016/j.ijantimicag.2011.12.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Revised: 12/06/2011] [Accepted: 12/07/2011] [Indexed: 11/26/2022]
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18
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Park YK, Jung SI, Park KH, Kim SH, Ko KS. Characteristics of carbapenem-resistant Acinetobacter spp. other than Acinetobacter baumannii in South Korea. Int J Antimicrob Agents 2011; 39:81-5. [PMID: 21996405 DOI: 10.1016/j.ijantimicag.2011.08.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 08/05/2011] [Accepted: 08/17/2011] [Indexed: 11/28/2022]
Abstract
Although many studies have been performed on carbapenem-resistant Acinetobacter baumannii, only a few studies have addressed carbapenem resistance in Acinetobacter spp. other than A. baumannii (non-baumannii Acinetobacter). Amongst 287 Acinetobacter spp. isolates from patients with bacteraemia in a South Korean hospital collected between 2003 and 2010, 160 (55.7%) were non-baumannii Acinetobacter spp. Antimicrobial susceptibility testing was performed and the effect of efflux pump inhibitors was examined. Antimicrobial resistance genes were identified and pulsed-field gel electrophoresis (PFGE) analysis was performed. OprD expression was also evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), and CarO disruption was investigated by PCR. Seventeen non-baumannii Acinetobacter isolates (10.6%) were resistant to imipenem or meropenem, comprising eight Acinetobacter pittii (or Acinetobacter genomospecies 3), four Acinetobacter nosocomialis (or Acinetobacter genomospecies 13TU), two Acinetobacter genomospecies 'close to 13TU', two Acinetobacter bereziniae (or Acinetobacter genomospecies 10) and one Acinetobacter genomospecies 16. bla(IMP-1) genes were detected in seven and two carbapenem-resistant A. pittii and A. bereziniae isolates, respectively. PFGE showed that A. pittii isolates carrying bla(IMP-1) belonged to the same clone. In addition, bla(SIM-1) and bla(PER-1) genes were simultaneously identified in two A. nosocomialis isolates. In four isolates (one each of A. pittii, A. nosocomialis, Acinetobacter genomospecies 'close to 13TU' and Acinetobacter genomospecies 16), efflux pumps were implicated in the increase in carbapenem minimum inhibitory concentrations. No decreased expression of OprD was identified in any carbapenem-resistant non-baumannii Acinetobacter isolates, and disruption of carO was also not detected. Clonal spread of carbapenem-resistant A. pittii carrying bla(IMP-1), which contributes to a high resistance rate in this species, was identified. The bla(IMP-1) and bla(SIM-1) genes were first identified in A. bereziniae and A. nosocomialis, respectively. Since no carbapenem resistance mechanisms could be identified, further efforts to find the resistance mechanism should be made.
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Affiliation(s)
- Young Kyoung Park
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, South Korea
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