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Sakuma M, Tohya M, Hishinuma T, Sherchand JB, Kirikae T, Tada T. Molecular epidemiology of multidrug-resistant Acinetobacter baumannii isolates from a hospital in Nepal. J Glob Antimicrob Resist 2024; 38:363-367. [PMID: 39117143 DOI: 10.1016/j.jgar.2024.07.017] [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: 06/04/2024] [Revised: 07/10/2024] [Accepted: 07/29/2024] [Indexed: 08/10/2024] Open
Abstract
OBJECTIVES The emergence of multidrug-resistant (MDR) Acinetobacter baumannii has become a serious worldwide medical problem. This study was designed to clarify the genetic and epidemiological properties of MDR A. baumannii clinical isolates. METHODS A total of 66 MDR A. baumannii isolates were obtained from 66 inpatients between May 2019 and February 2020 in a university hospital in Nepal. Whole genomes of these isolates were sequenced using next-generation sequencing. Phylogenetic trees were constructed from single nucleotide polymorphism concatemers. Multilocus sequence typing (MLST) and clonal complex (CC) analysis were conducted, and drug-resistance genes were identified. RESULTS Of the 66 isolates, 26 harboured a gene encoding NDM-type metallo-β-lactamase, and 55 harboured a gene encoding the 16S rRNA methyltransferase, ArmA. All isolates had point mutations in the quinolone-resistance-determining regions of gyrA and parC. Phylogenetic analysis showed that 55 isolates harboured armA, 26 harboured blaNDM-1, and14 harboured blaPER-7. Multilocus sequence typing and CC analysis revealed that 34 isolates belonged to CC2 (ST2), 10 to CC1 (nine ST1 and one ST623), and eight to CC149 (ST149). Compared to our previous study on MDR A. baumannii in Nepal in 2012, the isolation rate of CC2 increased, whereas that of CC149 decreased between 2012 and 2020. CONCLUSIONS This study indicates that MDR A. baumannii producing carbapenemase and 16S rRNA methyltransferase, with high resistance to carbapenems and/or aminoglycosides, are spreading in medical settings in Nepal. The genetic backgrounds of MDR A. baumannii isolates have shifted to international clone 2 over several years.
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Affiliation(s)
- Masafumi Sakuma
- Department of Microbiology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Mari Tohya
- National Institute of Health Sciences, Kawasaki, Kanagawa, Japan
| | - Tomomi Hishinuma
- Department of Microbiology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan
| | | | - Teruo Kirikae
- Juntendo University, Juntendo Advanced Research Institute of Health Science, Bunkyo, Japan
| | - Tatsuya Tada
- Department of Microbiology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
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Gurung A, Napit R, Shrestha B, Lekhak B. Carbapenem Resistance in Acinetobacter calcoaceticus-baumannii Complex Isolates From Kathmandu Model Hospital, Nepal, Is Attributed to the Presence of bla OXA-23-like and bla NDM-1 Genes. BIOMED RESEARCH INTERNATIONAL 2024; 2024:8842625. [PMID: 39161641 PMCID: PMC11333142 DOI: 10.1155/2024/8842625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 04/28/2024] [Accepted: 06/11/2024] [Indexed: 08/21/2024]
Abstract
The Acinetobacter calcoaceticus-baumannii (ACB) complex, also known as ACB complex, consists of four bacterial species that can cause opportunistic infections in humans, especially in hospital settings. Conventional therapies for susceptible strains of the ACB complex include broad-spectrum cephalosporins, β-lactam/β-lactamase inhibitors, and carbapenems. Unfortunately, the effectiveness of these antibiotics has declined due to increasing rates of resistance. The predominant resistance mechanisms identified in the ACB complex involve carbapenem-resistant (CR) oxacillinases and metallo-β-lactamases (MBLs). This research, conducted at Kathmandu Model Hospital in Nepal, sought to identify genes associated with CR, specifically blaNDM-1, blaOXA-23-like, and blaOXA-24-like genes in carbapenem-resistant Acinetobacter calcoaceticus-baumannii (CR-ACB) complex. Additionally, the study is aimed at identifying the ACB complex through the sequencing of the 16s rRNA gene. Among the 992 samples collected from hospitalized patients, 43 (approximately 4.334%) tested positive for the ACB complex. These positive samples were mainly obtained from different hospital units, including intensive care units (ICUs); cabins; and neonatal, general, and maternity wards. The prevalence of infection was higher among males (58.14%) than females (41.86%), with the 40-50 age group showing the highest infection rate. In susceptibility testing, colistin and polymyxin B exhibited a susceptibility rate of 100%, whereas all samples showed resistance to third-generation cephalosporins. After polymyxins, gentamicin (30.23%) and amikacin (34.88%) demonstrated the highest susceptibility. A substantial majority (81.45%) of ACB complex isolates displayed resistance to carbapenems, with respiratory and pus specimens being the primary sources. Polymerase chain reaction (PCR) revealed that the primary CR gene within the ACB complex at this hospital was bla OXA-23-like, followed by bla NDM-1. To ensure the accuracy of the phenotypic assessment, 12 samples were chosen for 16s rRNA sequencing using Illumina MiSeq™ to confirm that they are Acinetobacter species. QIIME 2.0 analysis confirmed all 12 isolates to be Acinetobacter species. In the hospital setting, a substantial portion of the ACB complex carries CR genes, rendering carbapenem ineffective for treatment.
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Affiliation(s)
- Anupama Gurung
- Central Department of MicrobiologyTribhuvan University, Kirtipur, Nepal
| | - Rajindra Napit
- Central Department of BiotechnologyTribhuvan University, Kirtipur, Nepal
| | - Basudha Shrestha
- Department of MicrobiologyKathmandu Model Hospital, Putalisadak, Kathmandu, Nepal
| | - Binod Lekhak
- Central Department of MicrobiologyTribhuvan University, Kirtipur, Nepal
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3
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Anita, Kumari R, Saurabh K, Kumar S, Kumari N. Comparative Evaluation of Broth Microdilution With Disc Diffusion and VITEK 2 for Susceptibility Testing of Colistin on Multidrug-Resistant Gram-Negative Bacteria. Cureus 2023; 15:e50894. [PMID: 38259409 PMCID: PMC10803103 DOI: 10.7759/cureus.50894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2023] [Indexed: 01/24/2024] Open
Abstract
Background The rise of antibiotic resistance, particularly in Gram-negative bacteria, poses a significant global health threat. Colistin, a last-resort antibiotic, has witnessed renewed use. However, accurate susceptibility testing for colistin is challenging, with various methods available, leading to potential discrepancies. Ensuring reliable testing is crucial for effective patient treatment and antimicrobial stewardship. This study addresses the need to compare different colistin susceptibility testing methods, providing insights into their accuracy and relevance in clinical settings. Methods In this one-year prospective observational cross-sectional study conducted at Indira Gandhi Institute of Medical Sciences (IGIMS), Bihar, India, a tertiary care hospital from July 2021 to June 2022, we aimed to evaluate the concordance between two widely used methods, VITEK 2 and Disc Diffusion, for antibiotic susceptibility testing in clinical multidrug-resistant Gram-negative bacterial isolates. These isolates, including species like Klebsiella pneumoniae, Acinetobacter baumannii, Klebsiella oxytoca, Pseudomonas aeruginosa, Citrobacter freundii, and Escherichia coli, were isolated from various clinical specimens. After rigorous species-level identification and quality control measures, antibiotic susceptibility testing was performed using both methods, and their agreement was assessed through Percentage Agreement analysis. Results In our study, we isolated and identified bacterial isolates from 105 patients, with a mean age of 47.30 years, demonstrating a wide age range. Pus samples were the most common type (25.7%), and K. pneumoniae was the most prevalent organism (45.7%). Antibiotic resistance patterns revealed significant challenges in treating infections caused by K. pneumoniae and A. baumannii, with resistance rates exceeding 70% for certain antibiotics. Among the 48 isolates of K. pneumoniae, the agreement was 93.8%, with 89.6% being sensitive and 6.3% being resistant by Disc Diffusion, while VITEK 2 indicated 0% resistance. E. coli isolates (n=21) had an agreement of 90.5%, with 90.5% sensitivity and 9.5% resistance by Disc Diffusion, and no resistance by VITEK 2. Conclusion The comparative analysis of antibiotic susceptibility testing methods reveals the superior performance of the VITEK 2 system, particularly in sensitivity and negative predictive value, emphasizing its potential as a reliable tool for guiding antibiotic therapy decisions.
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Affiliation(s)
- Anita
- Microbiology, Indira Gandhi Institute of Medical Sciences, Patna, IND
| | - Ritu Kumari
- Microbiology, Indira Gandhi Institute of Medical Sciences, Patna, IND
| | - Kumar Saurabh
- Microbiology, Indira Gandhi Institute of Medical Sciences, Patna, IND
| | - Santosh Kumar
- Emergency Medicine, Indira Gandhi Institute of Medical Sciences, Patna, IND
| | - Namrata Kumari
- Microbiology, Indira Gandhi Institute of Medical Sciences, Patna, IND
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Overcoming addition of phosphoethanolamine to lipid A mediated colistin resistance in Acinetobacter baumannii clinical isolates with colistin–sulbactam combination therapy. Sci Rep 2022; 12:11390. [PMID: 35794134 PMCID: PMC9259700 DOI: 10.1038/s41598-022-15386-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 06/23/2022] [Indexed: 01/08/2023] Open
Abstract
Overcoming colistin-resistant Acinetobacter baumannii (CoR-AB) has become a major concern due to the lack of effective antibiotics. This study aimed to explore the prevalence of CoR-AB clinical isolates in Thailand, their mechanisms of resistance, and test the efficacy of colistin plus sulbactam against CoR-AB isolates. The colistin resistance rate among carbapenem-resistant A. baumannii was 15.14%. The mcr gene or its variants were not detected in CoR-AB isolates by PCR screening. The lipid A mass spectra of CoR-AB isolates showed the additional [M–H]− ion peak at m/z = 2034 that correlated to the phosphoethanolamine (pEtN) addition to lipid A (N = 27/30). The important amino acid substitutions were found at position S14P, A138T, A227V in PmrB that are associated with overexpression of the pEtN transferase (PmrC) and contributed the pEtN addition. The lipopolysacccharide production genes (lpxACD) were not related to lipid A mass spectra. A colistin plus sulbactam combination exhibited the synergy rate at 86.7% against CoR-AB isolates compare to sulbactam (85.89% resistance) or colistin (15.14% resistance) alone. The excellent synergistic activity of colistin plus sulbactam combination has the potential for the treatment of CoR-AB infections.
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Bartoletti M, Antonelli A, Bussini L, Corcione S, Giacobbe DR, Marconi L, Pascale R, Dettori S, Shbaklo N, Ambretti S, Gaibani P, Giani T, Coppi M, Bassetti M, De Rosa FG, Marchese A, Cavallo R, Lewis R, Rossolini GM, Viale P, Giannella M. Clinical consequences of very major and errors with semi-automated testing systems for antimicrobial susceptibility of carbapenem-resistant enterobacterales. Clin Microbiol Infect 2022; 28:1290.e1-1290.e4. [DOI: 10.1016/j.cmi.2022.03.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 03/07/2022] [Accepted: 03/10/2022] [Indexed: 11/29/2022]
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Fadana V, Thomas T, von Knorring N. Retrospective analysis of Vitek ®2 performance compared to manual broth micro-dilution for colistin susceptibility testing of Acinetobacter baumanniicomplex isolates in South Africa. Afr J Lab Med 2022; 11:1597. [PMID: 35282395 PMCID: PMC8905463 DOI: 10.4102/ajlm.v11i1.1597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/27/2021] [Indexed: 11/17/2022] Open
Abstract
The manual broth micro-dilution (mBMD) is the recommended reference method for colistin minimum inhibitory concentration determination; however, it is not as readily available in South Africa as the Vitek®2. This retrospective study compared the performance of Vitek®2 against mBMD in determining the colistin minimum inhibitory concentration of 337 extensively drug-resistant Acinetobacter baumannii complex isolates. Vitek®2 yielded a categorical agreement of 89%, an essential agreement of 56%, a major error rate of 8% and a very major error rate of 55%. The Vitek®2 is not an alternative to mBMD for colistin susceptibility testing.
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Affiliation(s)
- Vuyolwethu Fadana
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Department Pathology, National Health Laboratory Services, Johannesburg, South Africa
| | - Teena Thomas
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Infectious Control Services Laboratory, National Health Laboratory Services, Johannesburg, South Africa
| | - Nina von Knorring
- School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Mycobacteriology Referral Laboratory, National Health Laboratory Service, Johannesburg, South Africa
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7
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Yang T, Mei H, Wang J, Cai Y. Therapeutic Drug Monitoring of Tigecycline in 67 Infected Patients and a Population Pharmacokinetics/Microbiological Evaluation of A. baumannii Study. Front Microbiol 2021; 12:678165. [PMID: 34220762 PMCID: PMC8241901 DOI: 10.3389/fmicb.2021.678165] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/19/2021] [Indexed: 11/26/2022] Open
Abstract
Background The widespread use of antibiotics has led to the emergence of multidrug-resistant (MDR) bacteria such as multidrug-resistant Acinetobacter baumannii (AB). Tigecycline (TGC), as the first glycylcycline antibiotic approved by FDA, is a broad-spectrum antibiotic which remains highly effective to treat AB infections. Objective To confirm the TGC treatment dosage and effectiveness to treat AB infections in the Chinese population by performing therapeutic drug monitoring (TDM). Methods This study was performed from October 2018 through March 2019 at the PLA General Hospital. A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was validated and employed to determine the plasma concentrations of TGC in patients with infectious diseases. The minimum inhibitory concentration (MIC) of TGC to clinically isolated AB was determined by broth microdilution method, agar dilution method, and disk diffusion method. Moreover, a model of population pharmacokinetics/pharmacodynamics (PPK/PD) was constructed. Results A total of 186 plasma samples from 67 patients were detected by the validated HPLC-MS/MS method. The MIC values determined by the broth microdilution method were more sensitive and accurate than the other two methods. The microbial and clinical PK/PD breakpoints were reached when the maintenance dose of TGC was 100 mg. Conclusion Our study established a validated HPLC-MS/MS method to monitor the plasma concentrations of TGC. In view of the MIC range to AB isolates in our hospital and the PPK/PD modeling results, we recommend a relatively high dose of 100 mg q12h regimen to achieve the optimal clinical efficacy and antimicrobial response.
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Affiliation(s)
- Tianli Yang
- Center of Medicine Clinical Research, Department of Pharmacy, Medical Supplies Center of Chinese PLA General Hospital, Beijing, China
| | - Hekun Mei
- Center of Medicine Clinical Research, Department of Pharmacy, Medical Supplies Center of Chinese PLA General Hospital, Beijing, China
| | - Jin Wang
- Center of Medicine Clinical Research, Department of Pharmacy, Medical Supplies Center of Chinese PLA General Hospital, Beijing, China
| | - Yun Cai
- Center of Medicine Clinical Research, Department of Pharmacy, Medical Supplies Center of Chinese PLA General Hospital, Beijing, China
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Elarabi MA. Answers to the authors of the "Letter to the Editor": A comparative study between non colistin based combinations for treatment of infections caused by extensive drug resistant Acinetobacter baumannii: comments. Int J Clin Pharm 2021; 43:1149-1151. [PMID: 33411179 DOI: 10.1007/s11096-020-01214-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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9
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Dafopoulou K, Vourli S, Tsakris A, Pournaras S. An update on polymyxin susceptibility testing methods for Acinetobacter baumannii. Expert Rev Anti Infect Ther 2019; 17:699-713. [DOI: 10.1080/14787210.2019.1667230] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Konstantina Dafopoulou
- Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Greece
- Laboratory of Clinical Microbiology, Attikon University Hospital, Athens, Greece
| | - Sophia Vourli
- Laboratory of Clinical Microbiology, Attikon University Hospital, Athens, Greece
| | - Athanasios Tsakris
- Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Greece
| | - Spyros Pournaras
- Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Greece
- Laboratory of Clinical Microbiology, Attikon University Hospital, Athens, Greece
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Mantzourani I, Bontsidis CA, Plessas S, Alexopoulos A, Theodoridou E, Tsigalou C, Voidarou C, Douganiotis G, Kazakos SL, Stavropoulou E, Bezirtzoglou E. Comparative Susceptibility Study Against Pathogens Using Fermented Cranberry Juice and Antibiotics. Front Microbiol 2019; 10:1294. [PMID: 31231355 PMCID: PMC6568244 DOI: 10.3389/fmicb.2019.01294] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/23/2019] [Indexed: 01/02/2023] Open
Abstract
In the present study, unfermented and fermented cranberry juice in combination with the Antibiotics vancomycin and tigecycline were tested for their antimicrobial activity. Cranberry juice was fermented with a recently isolated potentially probiotic Lactobacillus paracasei K5. The tested strains selected for this purpose were Enterococcus faecalis, E. faecium, Enterobacter cloacae and Staphylococcus aureus. The methods followed were the determination of zones inhibition, Minimum Inhibitory Concentration (MIC) and Fractional Inhibitory Concentration Index (FICI). Tigecycline together with fermented juice exhibited larger Zones of Inhibition (ZOI) in strains of E. faecium (65 ± 4.8 mm) compared to the respective ZOI with tigecycline and unfermented juice (no zone). The same outcome was also obtained with E. cloacae. Vancomycin together with fermented juice exhibited larger ZOI in strains of E. faecium (28 ± 2.2 mm) compared to the respective ZOI with vancomycin and unfermented juice (24 ± 2.3 mm). The lowest MIC values were recorded when tigecycline was combined with fermented cranberry juice against S. aureus strains, followed by the same combination of juice and antibiotic against E. cloacae strains. FICI revealed synergistic effects between fermented juice and tigecycline against a strain of E. faecium (A2020) and a strain of E. faecalis (A1940). Such effects were also observed in the case of fermented juice in combination with vancomycin against a strain of S. aureus (S18), as well as between fermented juice and tigecycline against E. cloacae (E1005 and E1007) strains. The results indicate that the antibacterial activity of juice fermented with the potentially probiotic L. paracasei K5 may be due to synergistic effects between some end fermentation products and the antibiotic agents examined.
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Affiliation(s)
- Ioanna Mantzourani
- Laboratory of Microbiology, Biotechnology and Hygiene, Faculty of Agriculture Development, Democritus University of Thrace, Orestiada, Greece
| | - Christos A. Bontsidis
- Laboratory of Microbiology, Biotechnology and Hygiene, Faculty of Agriculture Development, Democritus University of Thrace, Orestiada, Greece
| | - Stavros Plessas
- Laboratory of Microbiology, Biotechnology and Hygiene, Faculty of Agriculture Development, Democritus University of Thrace, Orestiada, Greece
| | - Athanasios Alexopoulos
- Laboratory of Microbiology, Biotechnology and Hygiene, Faculty of Agriculture Development, Democritus University of Thrace, Orestiada, Greece
| | - Eirini Theodoridou
- Laboratory of Microbiology, Biotechnology and Hygiene, Faculty of Agriculture Development, Democritus University of Thrace, Orestiada, Greece
| | - Christina Tsigalou
- Department of Agriculture, Faculty of Agriculture, Food Science, Nutrition, University of Ioannina, Ioannina, Greece
| | - Chrysa Voidarou
- Laboratory of Microbiology, Medical School, Democritus University of Thrace, Alexandroupolis, Greece
| | - George Douganiotis
- Theageneio Cancer Hospital, 3rd Department of Clinical Oncology, Thessaloniki, Greece
| | - Stavros L. Kazakos
- Laboratory of Microbiology, Biotechnology and Hygiene, Faculty of Agriculture Development, Democritus University of Thrace, Orestiada, Greece
| | - Elisavet Stavropoulou
- Service de Medicine Interne, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Eugenia Bezirtzoglou
- Laboratory of Microbiology, Biotechnology and Hygiene, Faculty of Agriculture Development, Democritus University of Thrace, Orestiada, Greece
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Comparison of susceptibility testing methods for determining the activity of colistin against Gram-negative bacilli of clinical origin. J Med Microbiol 2019; 68:60-66. [DOI: 10.1099/jmm.0.000879] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Bardet L, Rolain JM. Development of New Tools to Detect Colistin-Resistance among Enterobacteriaceae Strains. THE CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY = JOURNAL CANADIEN DES MALADIES INFECTIEUSES ET DE LA MICROBIOLOGIE MEDICALE 2018; 2018:3095249. [PMID: 30631384 PMCID: PMC6305056 DOI: 10.1155/2018/3095249] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/11/2018] [Indexed: 12/27/2022]
Abstract
The recent discovery of the plasmid-mediated mcr-1 gene conferring resistance to colistin is of clinical concern. The worldwide screening of this resistance mechanism among samples of different origins has highlighted the urgent need to improve the detection of colistin-resistant isolates in clinical microbiology laboratories. Currently, phenotypic methods used to detect colistin resistance are not necessarily suitable as the main characteristic of the mcr genes is the low level of resistance that they confer, close to the clinical breakpoint recommended jointly by the CLSI and EUCAST expert systems (S ≤ 2 mg/L and R > 2 mg/L). In this context, susceptibility testing recommendations for polymyxins have evolved and are becoming difficult to implement in routine laboratory work. The large number of mechanisms and genes involved in colistin resistance limits the access to rapid detection by molecular biology. It is therefore necessary to implement well-defined protocols using specific tools to detect all colistin-resistant bacteria. This review aims to summarize the current clinical microbiology diagnosis techniques and their ability to detect all colistin resistance mechanisms and describe new tools specifically developed to assess plasmid-mediated colistin resistance. Phenotyping, susceptibility testing, and genotyping methods are presented, including an update on recent studies related to the development of specific techniques.
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Affiliation(s)
- Lucie Bardet
- Aix-Marseille Université, IRD, AP-HM, MEPHI, IHU-Méditerranée Infection, Marseille, France
| | - Jean-Marc Rolain
- Aix-Marseille Université, IRD, AP-HM, MEPHI, IHU-Méditerranée Infection, Marseille, France
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Evaluation of the Rapid Polymyxin NP test for detection of colistin susceptibility in Enterobacteriaceae isolated from Thai patients. Diagn Microbiol Infect Dis 2018; 92:102-106. [PMID: 29884562 DOI: 10.1016/j.diagmicrobio.2018.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 05/10/2018] [Accepted: 05/10/2018] [Indexed: 11/21/2022]
Abstract
Development and evaluations of the Rapid Polymyxin NP test for detection of colistin resistance in Enterobacteriaceae have been recently reported. In this study, we evaluated the performance of the test using a larger number of Enterobacteriaceae, and a larger proportion of isolates with a colistin MIC close to the breakpoint. Out of 339 isolates, the Rapid Polymyxin NP test detected colistin resistance in 13 isolates of Escherichia coli, 213 isolates of Klebsiella pneumoniae, 9 isolates of Enterobacter aerogenes, and 10 isolates of the other Enterobacteriaceae species. Sensitivity and specificity of the test for detecting colistin resistance were 100% and 95.9%, respectively. Positive predictive value and negative predictive value were 98.3% and 100%, respectively.
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Vourli S, Dafopoulou K, Vrioni G, Tsakris A, Pournaras S. Evaluation of two automated systems for colistin susceptibility testing of carbapenem-resistant Acinetobacter baumannii clinical isolates. J Antimicrob Chemother 2018; 72:2528-2530. [PMID: 28605445 DOI: 10.1093/jac/dkx186] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 05/19/2017] [Indexed: 11/14/2022] Open
Abstract
Background Colistin is commonly needed for the treatment of infections due to carbapenem-resistant Acinetobacter baumannii (CRAB) and the determination of its in vitro activity is obviously important. However, the accurate routine antimicrobial susceptibility testing (AST) of colistin is still challenging. The only acceptable method for colistin AST is broth microdilution (BMD); disc and gradient diffusion assays are inappropriate and the performance of semi-automated systems has not been validated. Objectives In the present study, two commonly used semi-automated systems were evaluated for colistin AST of contemporary CRAB clinical isolates. Methods A total of 117 single-patient CRAB isolates collected randomly during 2015 from distinct tertiary hospitals located throughout Greece were tested. Colistin MICs were determined using the semi-automated systems Phoenix100 and Vitek2 and also agar dilution (AD), compared with the reference BMD. Results Colistin resistance rates for Phoenix100/Vitek2/AD/BMD were 15.4%/16.2%/35.9%/24.8%. The essential/categorical agreement rates were as follows: Phoenix100, 91.5%/88.9%; Vitek2, 88.9%/89.7%; and AD, 93.2%/87.2%. Alarmingly high rates of very major errors (VMEs) were observed for Phoenix100 (41.4%) and Vitek2 (37.9%), while major errors (MEs) were limited (1.1% by both systems); VMEs were much more common for isolates with MICs of 2 mg/L than for isolates with MICs of ≤ 1 mg/L, as determined by automated methods. AD produced considerably higher colistin MICs, yielding MEs of 15.9%. Conclusions Colistin resistance of A. baumannii is greatly underestimated by Phoenix100/Vitek2, potentially leading to inappropriate colistin administration. Colistin AST results by automated systems within the susceptible range, particularly those at the susceptibility breakpoint (2 mg/L), need to be validated by BMD.
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Affiliation(s)
- Sophia Vourli
- Laboratory of Clinical Microbiology, Attikon University Hospital, Athens, Greece
| | - Konstantina Dafopoulou
- Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Georgia Vrioni
- Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Athanassios Tsakris
- Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Spyros Pournaras
- Laboratory of Clinical Microbiology, Attikon University Hospital, Athens, Greece.,Department of Microbiology, Medical School, National and Kapodistrian University of Athens, Athens, Greece
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Singhal L, Sharma M, Verma S, Kaur R, Britto XB, Kumar SM, Ray P, Gautam V. Comparative Evaluation of Broth Microdilution with Polystyrene and Glass-Coated Plates, Agar Dilution, E-Test, Vitek, and Disk Diffusion for Susceptibility Testing of Colistin and Polymyxin B on Carbapenem-Resistant Clinical Isolates of Acinetobacter baumannii. Microb Drug Resist 2018; 24:1082-1088. [PMID: 29406804 DOI: 10.1089/mdr.2017.0251] [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] [Indexed: 11/12/2022] Open
Abstract
INTRODUCTION With the increasing threat of multidrug-resistant organisms, such as Acinetobacter baumannii, the polymyxin class of drugs (colistin and polymyxin B) has become popular in clinical practice. A better understanding of antimicrobial susceptibility testing methods for colistin and polymyxin B is needed for optimal patient management. MATERIALS AND METHODS Forty-two carbapenem-resistant A. baumannii isolates were subjected to susceptibility testing for colistin and polymyxin B using the following methods: broth microdilution (BMD) (glass-coated plates [BMD-Gs] and polystyrene plates [BMD-Ps]), agar dilution (AD), E-test®, Vitek®, and disk diffusion. Using BMD as the gold standard, comparative analysis between different methods was carried out. RESULTS With BMD-Gs as reference, reliability was high for BMD-Ps and moderate for AD and Vitek for both the drugs. Similar results were obtained when the BMD-P was used as reference, but drug-polystyrene interaction was observed. CONCLUSION Different susceptibility testing methods for polymyxins show great variation in their results and BMD using glass-coated plates can be considered the best candidate for gold standard.
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Affiliation(s)
- Lipika Singhal
- 1 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research , Chandigarh, India .,2 Department of Microbiology, GMCH , Chandigarh, India
| | - Megha Sharma
- 1 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research , Chandigarh, India
| | - Salony Verma
- 1 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research , Chandigarh, India
| | - Ramanpreet Kaur
- 1 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research , Chandigarh, India
| | - Xavier Basil Britto
- 3 Department of Medical Microbiology, Vaccine and Infectious Disease Institute, University of Antwerp , Antwerp, Belgium
| | - Surbhi Malhotra Kumar
- 3 Department of Medical Microbiology, Vaccine and Infectious Disease Institute, University of Antwerp , Antwerp, Belgium
| | - Pallab Ray
- 1 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research , Chandigarh, India
| | - Vikas Gautam
- 1 Department of Medical Microbiology, Post Graduate Institute of Medical Education and Research , Chandigarh, India
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Susceptibility Testing for the Polymyxins: Two Steps Back, Three Steps Forward? J Clin Microbiol 2017; 55:2573-2582. [PMID: 28724555 DOI: 10.1128/jcm.00888-17] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Optimizing and standardizing susceptibility testing for the polymyxins have become pressing issues, given the rise in multidrug-resistant Gram-negative bacilli. Recently, both the CLSI and EUCAST have recommended broth microdilution (BMD) (without polysorbate) as the reference method for polymyxin susceptibility testing. In this issue, K. L. Chew et al. (J Clin Microbiol 55:2609-2616, 2017, https://doi.org/10.1128/JCM.00268-17) compare the performances of three commercial BMD panels and the Etest to the reference, BMD, for polymyxin B and colistin, using 76 Enterobacteriaceae isolates (21 of which were mcr-1 positive). Although none of the commercial BMD panels strictly met FDA performance standards in this evaluation, possibly because of the small number isolates tested, the Sensititre panel achieved >90% categorical agreement for both polymyxin compounds. These results also reaffirm CLSI and EUCAST guidance that gradient diffusion testing, which had unacceptable error rates, should be abandoned. In a simulated analysis with lowered breakpoints (susceptible, ≤1 mg/liter; intermediate, 2 mg/liter; resistant, ≥4 mg/liter), error rates and agreement were improved across the various methods and the rate of detection of mcr-1-positive isolates improved. These observations, taken together with recent pharmacokinetic data on optimizing target attainment for the polymyxins, suggest that more-stringent (lower) breakpoints may be reasonable, although such an approach may be limited by the inherent reliability of current testing methodologies and a lack of robust clinical correlative data, which are sorely needed.
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17
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Leungtongkam U, Thummeepak R, Wongprachan S, Thongsuk P, Kitti T, Ketwong K, Runcharoen C, Chantratita N, Sitthisak S. Dissemination of bla OXA-23, bla OXA-24, bla OXA-58, and bla NDM-1 Genes of Acinetobacter baumannii Isolates from Four Tertiary Hospitals in Thailand. Microb Drug Resist 2017; 24:55-62. [PMID: 28594634 DOI: 10.1089/mdr.2016.0248] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Acinetobacter baumannii is a major threat to public health due to the emergence and dissemination of antibiotic-resistant strains. The purpose of this study was to determine the molecular epidemiology of antibiotic-resistant A. baumannii isolates collected from four tertiary hospitals in Thailand during the period November 2013-February 2015. We screened 339 A. baumannii, nonrepetitive clinical isolates to determine drug susceptibility. Among all isolates, we found that 7.9% was nondrug-resistant A. baumannii (NR-AB). Carbapenem-resistant A. baumannii (CR-AB) strains accounted for 84.9% of the total isolates, with extensively drug-resistant A. baumannii (XDR-AB) accounting for 7.9% of the total isolates. We further investigated class D carbapenemase genes using multiplex-PCR amplification and class B metallo-β-lactamase genes, including blaIMP, blaVIM, and blaNDM-1 genes, using PCR and sequencing methods. We found that 300 (88.5%) isolates carried acquired class D carbapenemase genes, including blaOXA-23 (82.6%), blaOXA-24 (0.3%), and blaOXA-58 (6.5%). The genes blaIMP and blaVIM were not detected in any isolates. The blaNDM-1 was detected in 31 isolates from two hospitals (9.1%). All of the blaNDM-1-positive A. baumannii (NDM-AB) had ISAba125 sequences upstream of the blaNDM-1 gene. A coexistence of three resistance genes-blaOXA-23-blaOXA-58-blaNDM-1-was found in one isolate. A repetitive element palindromic-PCR (REP-PCR) revealed that all A. baumannii isolates were genetically diverse and could be divided into 33 genotypes. Only three genotypes were found to be predominant in all hospitals. Data from our study indicate the widespread emergence of multiple resistance determinants in A. baumannii isolates in Thailand, suggesting the need for more stringent infection control measures.
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Affiliation(s)
- Udomluk Leungtongkam
- 1 Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University , Phitsanulok, Thailand
| | - Rapee Thummeepak
- 1 Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University , Phitsanulok, Thailand
| | | | - Pollawat Thongsuk
- 3 Chiangrai Prachanukroh Hospital , Amphoe Meuang, Chiangrai, Thailand
| | - Thawatchai Kitti
- 4 Department of Oriental Medicine, ChiangRai College , Chiangrai, Thailand
| | - Kwanjai Ketwong
- 5 Sawan Pracharak Hospital , Amphoe Meuang, Nakorn Sawan, Thailand
| | - Chakkaphan Runcharoen
- 6 Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University , Bangkok, Thailand
| | - Narisara Chantratita
- 6 Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University , Bangkok, Thailand
| | - Sutthirat Sitthisak
- 1 Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University , Phitsanulok, Thailand .,7 Centre of Excellence in Medical Biotechnology, Naresuan University , Phitsanulok, Thailand
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Moghnieh RA, Abdallah DI, Fawaz IA, Hamandi T, Kassem M, El-Rajab N, Jisr T, Mugharbil A, Droubi N, Al Tabah S, Sinno L, Ziade F, Daoud Z, Ibrahim A. Prescription Patterns for Tigecycline in Severely Ill Patients for Non-FDA Approved Indications in a Developing Country: A Compromised Outcome. Front Microbiol 2017; 8:497. [PMID: 28396656 PMCID: PMC5366332 DOI: 10.3389/fmicb.2017.00497] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/10/2017] [Indexed: 01/19/2023] Open
Abstract
Introduction: With the rise in antibiotic resistance, tigecycline has been used frequently in off-label indications, based on its in-vitro activity against multidrug-resistant organisms. In this study, our aim was to assess its use in approved and unapproved indications. Materials and Methods: This is a retrospective chart review evaluating a 2-year experience of tigecycline use for > 72 h in 153 adult patients inside and outside critical care unit from January 2012 to December 2013 in a Lebanese tertiary-care hospital. Results: Tigecycline was mostly used in off-label indications (81%) and prescribed inside the critical care area, where the number of tigecycline cycles was 16/1,000 patient days. Clinical success was achieved in 43.4% of the patients. In the critically ill group, it was significantly higher in patients with a SOFA score <7 using multivariate analysis (Odds Ratio (OR) = 12.51 [4.29–36.51], P < 0.0001). Microbiological success was achieved in 43.3% of patients. Yet, the univariate and adjusted multivariate models failed to show a significant difference in this outcome between patients inside vs. outside critical care area, those with SOFA score <7 vs. ≥ 7, and in FDA-approved vs. off-label indications. Total mortality reached ~45%. It was significantly higher in critically ill patients with SOFA score ≥7 (OR = 5.17 [2.43–11.01], P < 0.0001) and in off-label indications (OR = 4.00 [1.30–12.31], P = 0.01) using an adjusted multivariate model. Gram-negative bacteria represented the majority of the clinical isolates (81%) and Acinetobacter baumannii predominated (28%). Carbapenem resistance was present in 85% of the recovered Acinetobacter, yet, more than two third of the carbapenem-resistant Acinetobacter species were still susceptible to tigecycline. Conclusion: In our series, tigecycline has been mostly used in off-label indications, specifically in severely ill patients. The outcome of such infections was not inferior to that of FDA-approved indications, especially inside critical care area. The use of this last resort antibiotic in complicated clinical scenarios with baseline microbiological epidemiology predominated by extensively-drug resistant pathogens ought to be organized.
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Affiliation(s)
- Rima A Moghnieh
- Division of Infectious Diseases, Department of Internal Medicine, Makassed General HospitalBeirut, Lebanon; Faculty of Medicine, Beirut Arab UniversityBeirut, Lebanon; Faculty of Medical Sciences, Lebanese UniversityBeirut, Lebanon
| | | | - Ismail A Fawaz
- Department of Infectious Diseases, University of Balamand Amioun, Lebanon
| | - Tarek Hamandi
- Department of Internal Medicine, Makassed General Hospital Beirut, Lebanon
| | - Mohammad Kassem
- Department of Internal Medicine, Makassed General Hospital Beirut, Lebanon
| | - Nabila El-Rajab
- Department of Internal Medicine, Makassed General Hospital Beirut, Lebanon
| | - Tamima Jisr
- Department of Laboratory Medicine, Makassed General Hospital Beirut, Lebanon
| | - Anas Mugharbil
- Division of Hematology-Oncology, Department of Internal Medicine, Makassed General Hospital Beirut, Lebanon
| | - Nabila Droubi
- Pharmacy Department, Makassed General Hospital Beirut, Lebanon
| | - Samaa Al Tabah
- Faculty of Health Sciences, American University of Beirut Beirut, Lebanon
| | | | - Fouad Ziade
- Faculty of Public Health, Lebanese University Beirut, Lebanon
| | - Ziad Daoud
- Clinical Microbiology, Faculty of Medicine and Medical Sciences, University of Balamand Amioun, Lebanon
| | - Ahmad Ibrahim
- Faculty of Medical Sciences, Lebanese UniversityBeirut, Lebanon; Pharmacy Department, Makassed General HospitalBeirut, Lebanon; Division of Hematology-Oncology, Department of Internal Medicine, Makassed General HospitalBeirut, Lebanon
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Pantović V, Dinić M, Stanković Đorđević D, Kocić B, Bogdanović M. SUSCEPTIBILITY PATTERN OF CARBAPENEM-RESISTANT CLINICAL ISOLATES OF ACINETOBACTER SPP. ACTA MEDICA MEDIANAE 2016. [DOI: 10.5633/amm.2016.0412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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National epidemiology of carbapenem-resistant and extensively drug-resistant Gram-negative bacteria isolated from blood samples in China in 2013. Clin Microbiol Infect 2016; 22 Suppl 1:S1-8. [DOI: 10.1016/j.cmi.2015.09.015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 09/07/2015] [Accepted: 09/13/2015] [Indexed: 11/22/2022]
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In Vitro Activity of Tigecycline Against Acinetobacter baumannii: Global Epidemiology and Resistance Mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 897:1-14. [DOI: 10.1007/5584_2015_5001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Shrestha S, Tada T, Miyoshi-Akiyama T, Ohara H, Shimada K, Satou K, Teruya K, Nakano K, Shiroma A, Sherchand JB, Rijal BP, Hirano T, Kirikae T, Pokhrel BM. Molecular epidemiology of multidrug-resistant Acinetobacter baumannii isolates in a university hospital in Nepal reveals the emergence of a novel epidemic clonal lineage. Int J Antimicrob Agents 2015; 46:526-31. [PMID: 26362951 DOI: 10.1016/j.ijantimicag.2015.07.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 07/09/2015] [Accepted: 07/15/2015] [Indexed: 11/26/2022]
Abstract
The emergence of multidrug-resistant (MDR) Acinetobacter baumannii has become a serious medical problem worldwide. To clarify the genetic and epidemiological properties of MDR A. baumannii strains isolated from a medical setting in Nepal, 246 Acinetobacter spp. isolates obtained from different patients were screened for MDR A. baumannii by antimicrobial disk susceptibility testing. Whole genomes of the MDR A. baumannii isolates were sequenced by MiSeq™ (Illumina), and the complete genome of one isolate (IOMTU433) was sequenced by PacBio RS II. Phylogenetic trees were constructed from single nucleotide polymorphism concatemers. Multilocus sequence types were deduced and drug resistance genes were identified. Of the 246 Acinetobacter spp. isolates, 122 (49.6%) were MDR A. baumannii, with the majority being resistant to aminoglycosides, carbapenems and fluoroquinolones but not to colistin and tigecycline. These isolates harboured the 16S rRNA methylase gene armA as well as bla(NDM-1), bla(OXA-23) or bla(OXA-58). MDR A. baumannii isolates belonging to clonal complex 1 (CC1) and CC2 as well as a novel clonal complex (CC149) have spread throughout a medical setting in Nepal. The MDR isolates harboured genes encoding carbapenemases (OXA and NDM-1) and a 16S rRNA methylase (ArmA).
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Affiliation(s)
- Shovita Shrestha
- Department of Microbiology, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Tatsuya Tada
- Department of Infectious Diseases, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan
| | - Tohru Miyoshi-Akiyama
- Pathogenic Microbe Laboratory, Research Institute, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
| | - Hiroshi Ohara
- Department of International Medical-Cooperation, National Center for Global Health and Medicine, Tokyo 162-8655, Japan
| | - Kayo Shimada
- Department of Infectious Diseases, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan
| | - Kazuhito Satou
- Okinawa Institute of Advanced Science, Okinawa 904-2234, Japan
| | - Kuniko Teruya
- Okinawa Institute of Advanced Science, Okinawa 904-2234, Japan
| | - Kazuma Nakano
- Okinawa Institute of Advanced Science, Okinawa 904-2234, Japan
| | - Akino Shiroma
- Okinawa Institute of Advanced Science, Okinawa 904-2234, Japan
| | - Jeevan Bdr Sherchand
- Department of Microbiology, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Basista Psd Rijal
- Department of Microbiology, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Takashi Hirano
- Okinawa Institute of Advanced Science, Okinawa 904-2234, Japan
| | - Teruo Kirikae
- Department of Infectious Diseases, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan.
| | - Bharat Mani Pokhrel
- Department of Microbiology, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
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He S, He H, Chen Y, Chen Y, Wang W, Yu D. In vitro and in vivo analysis of antimicrobial agents alone and in combination against multi-drug resistant Acinetobacter baumannii. Front Microbiol 2015; 6:507. [PMID: 26074898 PMCID: PMC4444844 DOI: 10.3389/fmicb.2015.00507] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 05/08/2015] [Indexed: 11/13/2022] Open
Abstract
Objective: To investigate the in vitro and in vivo antibacterial activities of tigecycline and other 13 common antimicrobial agents, alone or in combination, against multi-drug resistant Acinetobacter baumannii. Methods: An in vitro susceptibility test of 101 A. baumannii was used to detect minimal inhibitory concentrations (MICs). A mouse lung infection model of multi-drug resistant A. baumannii, established by the ultrasonic atomization method, was used to define in vivo antimicrobial activities. Results: Multi-drug resistant A. baumannii showed high sensitivity to tigecycline (98% inhibition), polymyxin B (78.2% inhibition), and minocycline (74.2% inhibition). However, the use of these antimicrobial agents in combination with other antimicrobial agents produced synergistic or additive effects. In vivo data showed that white blood cell (WBC) counts in drug combination groups C (minocycline + amikacin) and D (minocycline + rifampicin) were significantly higher than in groups A (tigecycline) and B (polymyxin B) (P < 0.05), after administration of the drugs 24 h post-infection. Lung tissue inflammation gradually increased in the model group during the first 24 h after ultrasonic atomization infection; vasodilation, congestion with hemorrhage were observed 48 h post infection. After 3 days of anti-infective therapy in groups A, B, C, and D, lung tissue inflammation in each group gradually recovered with clear structures. The mortality rates in drug combination groups(groups C and D) were much lower than in groups A and B. Conclusion: The combination of minocycline with either rifampicin or amikacin is more effective against multi-drug resistant A. baumannii than single-agent tigecycline or polymyxin B. In addition, the mouse lung infection by ultrasonic atomization is a suitable model for drug screening and analysis of infection mechanism.
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Affiliation(s)
- Songzhe He
- The Affiliated First Hospital of Hangzhou, Zhejiang Chinese Medical University Hangzhou, China ; Department of Clinical Laboratories, Hangzhou First People's Hospital Hangzhou, China
| | - Hui He
- The Affiliated First Hospital of Hangzhou, Zhejiang Chinese Medical University Hangzhou, China ; Department of Clinical Laboratories, Hangzhou First People's Hospital Hangzhou, China
| | - Yi Chen
- The Affiliated First Hospital of Hangzhou, Zhejiang Chinese Medical University Hangzhou, China ; Department of Clinical Laboratories, Hangzhou First People's Hospital Hangzhou, China
| | - Yueming Chen
- Department of Clinical Laboratories, Hangzhou First People's Hospital Hangzhou, China
| | - Wei Wang
- Department of Clinical Laboratories, Hangzhou First People's Hospital Hangzhou, China
| | - Daojun Yu
- The Affiliated First Hospital of Hangzhou, Zhejiang Chinese Medical University Hangzhou, China ; Department of Clinical Laboratories, Hangzhou First People's Hospital Hangzhou, China
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