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Ouyang Z, He W, Jiao M, Yu Q, Guo Y, Refat M, Qin Q, Zhang J, Shi Q, Zheng F, Wen Y. Mechanistic and biophysical characterization of polymyxin resistance response regulator PmrA in Acinetobacter baumannii. Front Microbiol 2024; 15:1293990. [PMID: 38476937 PMCID: PMC10927774 DOI: 10.3389/fmicb.2024.1293990] [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: 09/14/2023] [Accepted: 02/05/2024] [Indexed: 03/14/2024] Open
Abstract
Introduction Acinetobacter baumannii PmrAB is a crucial two-component regulatory system (TCS) that plays a vital role in conferring resistance to polymyxin. PmrA, a response regulator belonging to the OmpR/PhoB family, is composed of a C-terminal DNA-binding effector domain and an N-terminal receiver domain. The receiver domain can be phosphorylated by PmrB, a transmembrane sensor histidine kinase that interacts with PmrA. Once phosphorylated, PmrA undergoes a conformational change, resulting in the formation of a symmetric dimer in the receiver domain. This conformational change facilitates the recognition of promoter DNA by the DNA-binding domain of PmrA, leading to the activation of adaptive responses. Methods X-ray crystallography was carried out to solve the structure of PmrA receiver domain. Electrophoretic mobility shift assay and Isothermal titration calorimetry were recruited to validate the interaction between the recombinant PmrA protein and target DNA. Field-emission scanning electron microscopy (FE-SEM) was employed to characterize the surface morphology of A. baumannii in both the PmrA knockout and mutation strains. Results The receiver domain of PmrA follows the canonical α5β5 response regulator assembly, which undergoes dimerization upon phosphorylation and activation. Beryllium trifluoride is utilized as an aspartate phosphorylation mimic in this process. Mutations involved in phosphorylation and dimerization significantly affected the expression of downstream pmrC and naxD genes. This impact resulted in an enhanced cell surface smoothness with fewer modifications, ultimately contributing to a decrease in colistin (polymyxin E) and polymyxin B resistance. Additionally, a conservative direct-repeat DNA PmrA binding sequence TTTAAGNNNNNTTTAAG was identified at the promoter region of the pmrC and naxD gene. These findings provide structural insights into the PmrA receiver domain and reveal the mechanism of polymyxin resistance, suggesting that PmrA could be a potential drug target to reverse polymyxin resistance in Acinetobacter baumannii.
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Affiliation(s)
- Zhenlin Ouyang
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Wenbo He
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Min Jiao
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Qinyue Yu
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Yucheng Guo
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Moath Refat
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Qian Qin
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Jiaxin Zhang
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Qindong Shi
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
| | - Fang Zheng
- The Key Laboratory of Environment and Genes Related to Disease of Ministry of Education Health Science Center, Xi'an Jiaotong University, Xi'an, China
| | - Yurong Wen
- Shaanxi Provincial Key Laboratory of Sepsis in Critical Care Medicine, Department of Critical Care Medicine, Center for Microbiome Research of Med-X Institute, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an, China
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Rout BP, Dash SK, Otta S, Behera B, Praharaj I, Sahu KK. Colistin resistance in carbapenem non-susceptible Acinetobacter baumanii in a tertiary care hospital in India: clinical characteristics, antibiotic susceptibility and molecular characterization. Mol Biol Rep 2024; 51:357. [PMID: 38400950 DOI: 10.1007/s11033-023-08982-5] [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: 09/09/2023] [Accepted: 10/24/2023] [Indexed: 02/26/2024]
Abstract
INTRODUCTION Acinetobacter baumanii (AB) is a bacterium of concern in the hospital setup due to its ability to thrive in unfavorable conditions and the rapid emergence of antibiotic resistance. Carbapenem resistance in this organism is disheartening, further clouded by the emergence of colistin resistance. AIM The present prospective study aims to note the epidemiology, molecular profile, and clinical outcome of patients with colistin resistance AB infections in a multispecialty tertiary care setup in Odisha, Eastern India. METHODS All AB strains received from March 2021 to February 2022, identified by Vitek2 (Biomerieux) and confirmed by oxa-51 genes, were included. Carbapenem and colistin resistance were identified as per CLSI guidelines. Known mutations for blaOXA-23-like, blaIMP, blaVIM, blaKP, lpxA, lpxC, pmrA, pmrB, and plasmid mediated mcr (mcr1-5) were screened by conventional PCR techniques. The clinical outcome was noted retrospectively from case sheets. Data was entered in MS Excel and tabulated using SPSS software. RESULTS In the study period, 350 AB were obtained, of which 317(90.5%) were carbapenem resistant (CRAB). Among the CRAB isolates, 19 (5.9%) were colistin resistant (ABCoR). The most valuable antibiotics in the study were tigecycline (65.4% in ABCoI; 31.6% in ABCoR) and minocycline (44.3% in CI; 36.8% in CR). There was a significant difference in mortality among ABCoI and ABCoR infections. bla OXA was the predominant carbapenem resistance genotype, while pmrA was the predominant colistin resistant genotype. There were no plasmid mediated mcr genes detected in the present study.
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Affiliation(s)
- Bidyut Prava Rout
- Department of Microbiology, IMS & SUM Hospital, Bhubaneswar, Odisha, India
| | - Sumesh Kumar Dash
- Department of Microbiology, IMS & SUM Hospital, Bhubaneswar, Odisha, India
| | - Sarita Otta
- Department of Microbiology, IMS & SUM Hospital, Bhubaneswar, Odisha, India.
| | - Birasen Behera
- Department of Microbiology, IMS & SUM Hospital, Bhubaneswar, Odisha, India
| | - Ira Praharaj
- Department of Virology, RMRC (ICMR), Bhubaneswar, Odisha, India
| | - Kundan Kumar Sahu
- Department of Microbiology, IMS & SUM Hospital, Bhubaneswar, Odisha, India.
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Vijayakumar S, Swetha RG, Bakthavatchalam YD, Vasudevan K, Abirami Shankar B, Kirubananthan A, Walia K, Ramaiah S, Biswas I, Veeraraghavan B, Anbarasu A. Genomic investigation unveils colistin resistance mechanism in carbapenem-resistant Acinetobacter baumannii clinical isolates. Microbiol Spectr 2024; 12:e0251123. [PMID: 38214512 PMCID: PMC10846133 DOI: 10.1128/spectrum.02511-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 11/29/2023] [Indexed: 01/13/2024] Open
Abstract
Colistin resistance in Acinetobacter baumannii is mediated by multiple mechanisms. Recently, mutations within pmrABC two-component system and overexpression of eptA gene due to upstream insertion of ISAba1 have been shown to play a major role. Thus, the aim of our study is to characterize colistin resistance mechanisms among the clinical isolates of A. baumannii in India. A total of 207 clinical isolates of A. baumannii collected from 2016 to 2019 were included in this study. Mutations within lipid A biosynthesis and pmrABC genes were characterized by whole-genome shotgun sequencing. Twenty-eight complete genomes were further characterized by hybrid assembly approach to study insertional inactivation of lpx genes and the association of ISAba1-eptA. Several single point mutations (SNPs), like M12I in pmrA, A138T and A444V in pmrB, and E117K in lpxD, were identified. We are the first to report two novel SNPs (T7I and V383I) in the pmrC gene. Among the five colistin-resistant A. baumannii isolates where complete genome was available, the analysis showed that three of the five isolates had ISAba1 insertion upstream of eptA. No mcr genes were identified among the isolates. We mapped the SNPs on the respective protein structures to understand the effect on the protein activity. We found that majority of the SNPs had little effect on the putative protein function; however, some SNPs might destabilize the local structure. Our study highlights the diversity of colistin resistance mechanisms occurring in A. baumannii, and ISAba1-driven eptA overexpression is responsible for colistin resistance among the Indian isolates.IMPORTANCEAcinetobacter baumannii is a Gram-negative, emerging and opportunistic bacterial pathogen that is often associated with a wide range of nosocomial infections. The treatment of these infections is hindered by increase in the occurrence of A. baumannii strains that are resistant to most of the existing antibiotics. The current drug of choice to treat the infection caused by A. baumannii is colistin, but unfortunately, the bacteria started to show resistance to the last-resort antibiotic. The loss of lipopolysaccharides and mutations in lipid A biosynthesis genes are the main reasons for the colistin resistance. The present study characterized 207 A. baumannii clinical isolates and constructed complete genomes of 28 isolates to recognize the mechanisms of colistin resistance. We showed the mutations in the colistin-resistant variants within genes essential for lipid A biosynthesis and that cause these isolates to lose the ability to produce lipopolysaccharides.
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Affiliation(s)
- Saranya Vijayakumar
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Rayapadi G. Swetha
- Medical and Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | | | - Karthick Vasudevan
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
- Department of Biotechnology, School of Applied Sciences, REVA University, Bangalore, India
| | - Baby Abirami Shankar
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | | | - Kamini Walia
- Division of Epidemiology and Communicable Diseases, Indian Council for Medical Research, New Delhi, India
| | - Sudha Ramaiah
- Medical and Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
| | - Indranil Biswas
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas, USA
| | - Balaji Veeraraghavan
- Department of Clinical Microbiology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Anand Anbarasu
- Medical and Biological Computing Laboratory, School of Biosciences and Technology, Vellore Institute of Technology (VIT), Vellore, Tamil Nadu, India
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Shi J, Cheng J, Liu S, Zhu Y, Zhu M. Acinetobacter baumannii: an evolving and cunning opponent. Front Microbiol 2024; 15:1332108. [PMID: 38318341 PMCID: PMC10838990 DOI: 10.3389/fmicb.2024.1332108] [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: 11/02/2023] [Accepted: 01/08/2024] [Indexed: 02/07/2024] Open
Abstract
Acinetobacter baumannii is one of the most common multidrug-resistant pathogens causing nosocomial infections. The prevalence of multidrug-resistant A. baumannii infections is increasing because of several factors, including unregulated antibiotic use. A. baumannii drug resistance rate is high; in particular, its resistance rates for tigecycline and polymyxin-the drugs of last resort for extensively drug-resistant A. baumannii-has been increasing annually. Patients with a severe infection of extensively antibiotic-resistant A. baumannii demonstrate a high mortality rate along with a poor prognosis, which makes treating them challenging. Through carbapenem enzyme production and other relevant mechanisms, A. baumannii has rapidly acquired a strong resistance to carbapenem antibiotics-once considered a class of strong antibacterials for A. baumannii infection treatment. Therefore, understanding the resistance mechanism of A. baumannii is particularly crucial. This review summarizes mechanisms underlying common antimicrobial resistance in A. baumannii, particularly those underlying tigecycline and polymyxin resistance. This review will serve as a reference for reasonable antibiotic use at clinics, as well as new antibiotic development.
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Affiliation(s)
- Jingchao Shi
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
- Department of Clinical Laboratory, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, China
- Graduate School, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jianghao Cheng
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
| | - Shourong Liu
- Department of Infectious Disease, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
| | - Yufeng Zhu
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
| | - Mingli Zhu
- Open Laboratory Medicine, Hangzhou Xixi Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
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Shelenkov A, Akimkin V, Mikhaylova Y. International Clones of High Risk of Acinetobacter Baumannii-Definitions, History, Properties and Perspectives. Microorganisms 2023; 11:2115. [PMID: 37630675 PMCID: PMC10459012 DOI: 10.3390/microorganisms11082115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/24/2023] [Accepted: 08/10/2023] [Indexed: 08/27/2023] Open
Abstract
Acinetobacter baumannii is a Gram-negative coccobacillus with exceptional survival skills in an unfavorable environment and the ability to rapidly acquire antibiotic resistance, making it one of the most successful hospital pathogens worldwide, representing a serious threat to public health. The global dissemination of A. baumannii is driven by several lineages named 'international clones of high risk' (ICs), two of which were first revealed in the 1970s. Epidemiological surveillance is a crucial tool for controlling the spread of this pathogen, which currently increasingly involves whole genome sequencing. However, the assignment of a particular A. baumannii isolate to some IC based on its genomic sequence is not always straightforward and requires some computational skills from researchers, while the definitions found in the literature are sometimes controversial. In this review, we will focus on A. baumannii typing tools suitable for IC determination, provide data to easily determine IC assignment based on MLST sequence type (ST) and intrinsic blaOXA-51-like gene variants, discuss the history and current spread data of nine known ICs, IC1-IC9, and investigate the representation of ICs in public databases. MLST and cgMLST profiles, as well as OXA-51-like presence data are provided for all isolates available in GenBank. The possible emergence of a novel A. baumannii international clone, IC10, will be discussed.
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Affiliation(s)
- Andrey Shelenkov
- Central Research Institute of Epidemiology, Novogireevskaya Str., 3a, 111123 Moscow, Russia
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Zafer MM, Hussein AFA, Al-Agamy MH, Radwan HH, Hamed SM. Retained colistin susceptibility in clinical Acinetobacter baumannii isolates with multiple mutations in pmrCAB and lpxACD operons. Front Cell Infect Microbiol 2023; 13:1229473. [PMID: 37600939 PMCID: PMC10436201 DOI: 10.3389/fcimb.2023.1229473] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/10/2023] [Indexed: 08/22/2023] Open
Abstract
The progressive increase in the resistance rates to first- and second-line antibiotics has forced the reuse of colistin as last-line treatment for Acinetobacter baumannii infections, but the emergence of colistin-resistant strains is not uncommon. This has been long linked to acquired chromosomal mutations in the operons pmrCAB and lpxACD. Hence, such mutations are routinely screened in colistin-resistant strains by most studies. The current study was designed to explore the possible existence of pmrCAB and lpxACD mutations in colistin-susceptible isolates. For this purpose, the whole genome sequences of eighteen multi-/extensively drug resistant A. baumannii were generated by Illumina sequencing and screened for missense mutations of the operons pmrCAB and lpxACD. Most of the isolates belonged to global clones (GCs) including GC1 (n=2), GC2 (n=7), GC7 (n=2), GC9 (n=3), and GC11 (n=1). The minimum inhibitory concentrations (MICs) of colistin were determined by the broth microdilution assay. Seventeen isolates were fully susceptible to colistin with MICs ranging from (≤0.125 to 0.5 µg/ml). Interestingly, all colistin-susceptible isolates carried missense mutations in pmrCAB and lpxACD operons with reference to A. baumannii ATCC 19606. Overall, 34 mutations were found. Most substitutions were detected in pmrC (n=20) while no mutations were found in pmrA or lpxA. Notably, the mutation pattern of the two operons was almost conserved among the isolates that belonged to the same sequence type (ST) or GC. This was also confirmed by expanding the analysis to include A. baumannii genomes deposited in public databases. Here, we demonstrated the possible existence of missense mutations in pmrCAB and lpxACD operons in colistin-susceptible isolates, shedding light on the importance of interpreting mutations with reference to colistin-susceptible isolates of the same ST/GC to avoid the misleading impact of the ST/GC-related polymorphism. In turn, this may lead to misinterpretation of mutations and, hence, overlooking the real players in colistin resistance that are yet to be identified.
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Affiliation(s)
- Mai M. Zafer
- Department of Microbiology and Immunology, Faculty of Pharmacy, Ahram Canadian University, Cairo, Egypt
| | - Amira F. A. Hussein
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
- Faculty of Applied Health Science, Galala University, Cairo, Egypt
| | - Mohamed H. Al-Agamy
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
- Department of Microbiology and Immunology, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt
| | - Hesham H. Radwan
- Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Samira M. Hamed
- Department of Microbiology and Immunology, Faculty of Pharmacy, October University for Modern Sciences and Arts (MSA), 6th of October, Giza, Egypt
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Colistin Resistance in Acinetobacter baumannii: Molecular Mechanisms and Epidemiology. Antibiotics (Basel) 2023; 12:antibiotics12030516. [PMID: 36978383 PMCID: PMC10044110 DOI: 10.3390/antibiotics12030516] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/17/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Acinetobacter baumannii is recognized as a clinically significant pathogen causing a wide spectrum of nosocomial infections. Colistin was considered a last-resort antibiotic for the treatment of infections caused by multidrug-resistant A. baumannii. Since the reintroduction of colistin, a number of mechanisms of colistin resistance in A. baumannii have been reported, including complete loss of LPS by inactivation of the biosynthetic pathway, modifications of target LPS driven by the addition of phosphoethanolamine (PEtN) moieties to lipid A mediated by the chromosomal pmrCAB operon and eptA gene-encoded enzymes or plasmid-encoded mcr genes and efflux of colistin from the cell. In addition to resistance to colistin, widespread heteroresistance is another feature of A. baumannii that leads to colistin treatment failure. This review aims to present a critical assessment of relevant published (>50 experimental papers) up-to-date knowledge on the molecular mechanisms of colistin resistance in A. baumannii with a detailed review of implicated mutations and the global distribution of colistin-resistant strains.
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Kabic J, Novovic K, Kekic D, Trudic A, Opavski N, Dimkic I, Jovcic B, Gajic I. Comparative genomics and molecular epidemiology of colistin-resistant Acinetobacter baumannii. Comput Struct Biotechnol J 2022; 21:574-585. [PMID: 36659926 PMCID: PMC9816908 DOI: 10.1016/j.csbj.2022.12.045] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/27/2022] [Accepted: 12/27/2022] [Indexed: 12/29/2022] Open
Abstract
This study aimed to investigate the prevalence and resistance mechanisms of colistin-resistant Acinetobacter baumannii (ColRAB) isolates in Serbia, assess their genetic relatedness to other circulating A. baumannii isolates in the neighbouring European countries, and analyse the global genomic epidemiology of ColRAB isolates. A total of 784 isolates of A. baumannii were recovered from hospitalised patients in Serbia between 2018 and 2021. The antimicrobial susceptibility testing was performed using disk diffusion and broth microdilution. All ColRAB isolates were subjected to DNA isolation and whole-genome sequencing (WGS). Overall, 3.94 % (n = 30) isolates were confirmed as ColRAB. Results of mutational and transcriptional analysis of genes associated with colistin resistance indicate the central role of the two-component regulating system, PmrAB, and increased expression of the pmrC gene in ColRAB. Most of the isolates (n = 29, 96.6 %) belonged to international clone II, with the most common sequence type being STPas2 (n = 23, 76.6 %). Based on the WGS analysis, ColRAB isolates belonging to the same ST isolated in various countries were grouped into the same clusters, indicating the global dissemination of several high-risk clonal lineages. Phylogenomic analysis of ColRAB isolates, together with all previously published A. baumannii genomes from South-Eastern European countries, showed that colistin resistance arose independently in several clonal lineages. Comparative genomic analysis revealed multiple genes with various roles (transcriptional regulation, transmembrane transport, outer membrane assembly, etc.), which might be associated with colistin resistance in A. baumannii. The obtained findings serve as the basis for further studies, contributing to a better understanding of colistin resistance mechanisms in A. baumannii.
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Affiliation(s)
- Jovana Kabic
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Katarina Novovic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, 11000, Belgrade, Serbia
| | - Dusan Kekic
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Anika Trudic
- Department of Microbiology, Faculty of Medicine, University of Novi Sad, 21000, Novi Sad, Serbia
- Institute for Pulmonary Diseases of Vojvodina, 21204, Sremska Kamenica, Serbia
| | - Natasa Opavski
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
| | - Ivica Dimkic
- Faculty of Biology, University of Belgrade, 11000, Belgrade, Serbia
| | - Branko Jovcic
- Laboratory for Molecular Microbiology, Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, 11000, Belgrade, Serbia
- Faculty of Biology, University of Belgrade, 11000, Belgrade, Serbia
- Correspondence to: Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, Faculty of Biology, University of Belgrade Studentski trg 16, 11000 Belgrade, Serbia.
| | - Ina Gajic
- Institute of Microbiology and Immunology, Faculty of Medicine, University of Belgrade, 11000, Belgrade, Serbia
- Correspondence to: Institute of Microbiology and Immunology, Medical Faculty, University of Belgrade Dr Subotica 1, 11000 Belgrade, Serbia.
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Seleim SM, Mostafa MS, Ouda NH, Shash RY. The role of pmrCAB genes in colistin-resistant Acinetobacter baumannii. Sci Rep 2022; 12:20951. [PMID: 36470921 PMCID: PMC9722906 DOI: 10.1038/s41598-022-25226-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 11/28/2022] [Indexed: 12/11/2022] Open
Abstract
The progressively increasing antimicrobial-resistant Acinetobacter baumannii infections have enforced the use of colistin as the last option for therapy, resulting in the colistin resistance evolution. This work aimed to study the pmrCAB expression in A. baumannii isolates as well as the presence of the mcr-1 gene. Colistin MICs of 100 A. baumannii isolates were measured using the broth microdilution assay. In four colistin-susceptible and four colistin-resistant isolates, the relative expression of the pmrA, pmrB, and pmrC genes was determined using reverse transcription PCR, and then selected isolates were sequenced using the Sanger technique. Finally, the mcr-1 gene was detected using conventional PCR. The colistin resistance rate among the studied isolates was 49%. The expression levels of pmrA and pmrB were statistically significantly higher in colistin-resistant isolates than in colistin-susceptible ones, while the pmrC expression had no statistically significant change. There was a weak positive correlation between colistin MICs and the expression levels of each of the pmrA and pmrB genes. By sequencing, two colistin-resistant strains with low pmrCAB expression showed insertion mutations 3277188_3277189T in pmrB and 1185149_1185150T in pmrC. Only one isolate (1%) was positive for the presence of mcr-1. We concluded that pmrCAB increased expression and/or mutations may cause colistin resistance in A. baumannii. However, increased pmrC expression may not necessarily result in colistin resistance. In Egypt, this is the first study to reveal the existence of mcr-1 in A. baumanni. This should attract attention in clinical settings due to the ultimate tendency of spreading colistin resistance.
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Affiliation(s)
- Shaimaa Mohamed Seleim
- grid.7776.10000 0004 0639 9286Department of Medical Microbiology and Immunology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Marwa Salah Mostafa
- grid.7776.10000 0004 0639 9286Department of Medical Microbiology and Immunology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Nadia Hafez Ouda
- grid.7776.10000 0004 0639 9286Department of Medical Microbiology and Immunology, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Rania Yahia Shash
- grid.7776.10000 0004 0639 9286Department of Medical Microbiology and Immunology, Faculty of Medicine, Cairo University, Cairo, Egypt
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Kamoshida G, Yamada N, Nakamura T, Yamaguchi D, Kai D, Yamashita M, Hayashi C, Kanda N, Sakaguchi M, Morimoto H, Sawada T, Okada T, Kaya Y, Takemoto N, Yahiro K. Preferential Selection of Low-Frequency, Lipopolysaccharide-Modified, Colistin-Resistant Mutants with a Combination of Antimicrobials in Acinetobacter baumannii. Microbiol Spectr 2022; 10:e0192822. [PMID: 36173297 PMCID: PMC9602988 DOI: 10.1128/spectrum.01928-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 09/13/2022] [Indexed: 12/31/2022] Open
Abstract
Colistin, which targets lipopolysaccharide (LPS), is used as a last-resort drug against severe infections caused by drug-resistant Acinetobacter baumannii. However, A. baumannii possesses two colistin-resistance mechanisms. LPS modification caused by mutations in pmrAB genes is often observed in clinical isolates of multidrug-resistant Gram-negative pathogens. In addition to LPS modification, A. baumannii has a unique colistin resistance mechanism, a complete loss of LPS due to mutations in the lpxACD genes, which are involved in LPS biosynthesis. This study aimed to elucidate the detailed mechanism of the emergence of colistin-resistant A. baumannii using strains with the same genetic background. Various colistin-resistant strains were generated experimentally using colistin alone and in combination with other antimicrobials, such as meropenem and ciprofloxacin, and the mutation spectrum was analyzed. In vitro selection of A. baumannii in the presence of colistin led to the emergence of strains harboring mutations in lpxACD genes, resulting in LPS-deficient colistin-resistant strains. However, combination of colistin with other antimicrobials led to the selection of pmrAB mutant strains, resulting in strains with modified LPS (LPS-modified strains). Further, the LPS-deficient strains showed decreased fitness and increased susceptibility to many antibiotics and disinfectants. As LPS-deficient strains have a higher biological cost than LPS-modified strains, our findings suggested that pmrAB mutants are more likely to be isolated in clinical settings. We provide novel insights into the mechanisms of resistance to colistin and provide substantial solutions along with precautions for facilitating current research and treatment of colistin-resistant A. baumannii infections. IMPORTANCE Acinetobacter baumannii has developed resistance to various antimicrobial drugs, and its drug-resistant strains cause nosocomial infections. Controlling these infections has become a global clinical challenge. Carbapenem antibiotics are the frontline treatment drugs for infectious diseases caused by A. baumannii. For patients with infections caused by carbapenem-resistant A. baumannii, colistin-based therapy is often the only treatment option. However, A. baumannii readily acquires resistance to colistin. Many patients infected with colistin-resistant A. baumannii undergo colistin treatment before isolation of the colistin-resistant strain, and it is hypothesized that colistin resistance predominantly emerges under selective pressure during colistin therapy. Although the concomitant use of colistin and carbapenems has been reported to have a synergistic effect in vitro against carbapenem-resistant A. baumannii strains, our observations strongly suggest the need for attention to the emergence of strains with a modified lipopolysaccharide during treatment.
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Affiliation(s)
- Go Kamoshida
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Noriteru Yamada
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Tomoka Nakamura
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Daiki Yamaguchi
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Daichi Kai
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Maho Yamashita
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Chiaki Hayashi
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Nana Kanda
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Moe Sakaguchi
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Hitoshi Morimoto
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Teppei Sawada
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Tomoko Okada
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Yuki Kaya
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Norihiko Takemoto
- Pathogenic Microbe Laboratory, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan
| | - Kinnosuke Yahiro
- Department of Microbiology and Infection Control Sciences, Kyoto Pharmaceutical University, Kyoto, Japan
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11
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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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12
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pmrCAB Recombination Events among Colistin-Susceptible and -Resistant Acinetobacter baumannii Clinical Isolates Belonging to International Clone 7. mSphere 2021; 6:e0074621. [PMID: 34851165 PMCID: PMC8636104 DOI: 10.1128/msphere.00746-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Acinetobacter baumannii is a successful nosocomial pathogen due to its genomic plasticity. Homologous recombination allows genetic exchange and allelic variation among different clonal lineages and is one of the mechanisms associated with horizontal gene transfer (HGT) of resistance determinants. The main mechanism of colistin resistance in A. baumannii is mediated through mutations in the pmrCAB operon. Here, we describe two A. baumannii clinical isolates belonging to International Clone 7 (IC7) that have undergone recombination in the pmrCAB operon and evaluate the contribution of mobile genetic elements (MGE) to this phenomenon. Isolates 67569 and 72554 were colistin susceptible and resistant, respectively, and were submitted for short- and long-read genome sequencing using Illumina MiSeq and MinION platforms. Hybrid assemblies were built with Unicycler, and the assembled genomes were compared to reference genomes using NUCmer, Cortex, and SplitsTree. Genomes were annotated using Prokka, and MGEs were identified with ISfinder and repeat match. Both isolates presented a 21.5-kb recombining region encompassing pmrCAB. In isolate 67659, this region originated from IC5, while in isolate 72554 multiple recombination events might have happened, with the 5-kb recombining region encompassing pmrCAB associated with an isolate representing IC4. We could not identify MGEs involved in the mobilization of pmrCAB in these isolates. In summary, A. baumannii belonging to IC7 can present additional sequence divergence due to homologous recombination across clonal lineages. Such variation does not seem to be driven by antibiotic pressure but could contribute to HGT mediating colistin resistance. IMPORTANCE Colistin resistance rates among Acinetobacter baumannii clinical isolates have increased over the last 20 years. Despite reports of the spread of plasmid-mediated colistin resistance among Enterobacterales, the presence of mcr-type genes in Acinetobacter spp. remains rare, and reduced colistin susceptibility is mainly associated with the acquisition of nonsynonymous mutations in pmrCAB. We have recently demonstrated that distinct pmrCAB sequences are associated with different A. baumannii International Clones (IC). In this study, we identified the presence of homologous recombination as an additional cause of genetic variation in this operon, which, to the best of our knowledge, was not mediated by mobile genetic elements. Even though this phenomenon was observed in both colistin-susceptible and -resistant isolates, it has the potential to contribute to the spread of resistance-conferring alleles, leading to reduced susceptibility to this last-resort antimicrobial agent.
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13
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King A, Blackledge MS. Evaluation of small molecule kinase inhibitors as novel antimicrobial and antibiofilm agents. Chem Biol Drug Des 2021; 98:1038-1064. [PMID: 34581492 PMCID: PMC8616828 DOI: 10.1111/cbdd.13962] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/24/2021] [Accepted: 09/15/2021] [Indexed: 12/25/2022]
Abstract
Antibiotic resistance is a global and pressing concern. Our current therapeutic arsenal is increasingly limited as bacteria are developing resistance at a rate that far outpaces our ability to create new treatments. Novel approaches to treating and curing bacterial infections are urgently needed. Bacterial kinases have been increasingly explored as novel drug targets and are poised for development into novel therapeutic agents to combat bacterial infections. This review describes several general classes of bacterial kinases that play important roles in bacterial growth, antibiotic resistance, and biofilm formation. General features of these kinase classes are discussed and areas of particular interest for the development of inhibitors will be highlighted. Small molecule kinase inhibitors are described and organized by phenotypic effect, spotlighting particularly interesting inhibitors with novel functions and potential therapeutic benefit. Finally, we provide our perspective on the future of bacterial kinase inhibition as a viable strategy to combat bacterial infections and overcome the pressures of increasing antibiotic resistance.
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Affiliation(s)
- Ashley King
- Department of Chemistry, High Point University, One University Parkway, High Point, NC 27268
| | - Meghan S. Blackledge
- Department of Chemistry, High Point University, One University Parkway, High Point, NC 27268
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14
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Yoon EJ, Kim HS, Woo H, Choi YJ, Won D, Choi JR, Kim YA, Jeong SH. Trajectory of genetic alterations associated with colistin resistance in Acinetobacter baumannii during an in-hospital outbreak of infection. J Antimicrob Chemother 2021; 77:69-73. [PMID: 34609499 DOI: 10.1093/jac/dkab363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/06/2021] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND As carbapenem-resistant Acinetobacter baumannii is dominant in clinical settings, the old polymyxin antibiotic colistin has been revived as a therapeutic option. The development of colistin resistance during treatment is becoming a growing concern. OBJECTIVES To access low- to mid-level colistin-resistant A. baumannii blood isolates recovered from an outbreak in a tertiary care hospital from a national antimicrobial surveillance study. METHODS The entire bacterial genome was sequenced through long-read sequencing methodology. Quantitative RT-PCR was carried out to determine the level of gene expression. Relative growth rates were determined to estimate fitness costs of each isolate caused by the genetic alterations. RESULTS The A. baumannii isolates belonged to global clone 2 harbouring two intrinsic phosphoethanolamine transferases. Cumulative alterations continuing the colistin resistance were observed. PmrC overproduction caused by the PmrBA226T alteration was identified in A. baumannii isolates with low-level colistin resistance and an additional PmrCR109H substitution led to mid-level colistin resistance. Truncation of the PmrC enzyme by insertion of ISAba59 was compensated by ISAba10-mediated overproduction of EptA and, in the last isolate, the complete PmrAB two-component regulatory system was eliminated to restore the biological cost of the bacterial host. CONCLUSIONS During the in-hospital outbreak, a trajectory of genetic modification in colistin-resistant A. baumannii isolates was observed for survival in the harsh conditions imposed by life-threatening drugs with the clear purpose of maintaining drug resistance above a certain level with a reasonable fitness cost.
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Affiliation(s)
- Eun-Jeong Yoon
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, South Korea.,Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, South Korea
| | - Hyun Soo Kim
- Department of Laboratory Medicine, Hallym University Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, South Korea
| | - Heungjeong Woo
- Department of Infectious Diseases, Hallym University Dongtan Sacred Heart Hospital, Hallym University College of Medicine, Hwaseong, South Korea
| | - You Jeong Choi
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, South Korea.,Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, South Korea
| | - Dongju Won
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Jong Rak Choi
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Young Ah Kim
- Department of Laboratory Medicine, National Health Insurance Service Ilsan Hospital, Goyang, South Korea
| | - Seok Hoon Jeong
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, South Korea.,Research Institute of Bacterial Resistance, Yonsei University College of Medicine, Seoul, South Korea
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15
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Yang YS, Jeng WY, Lee YT, Hsu CJ, Chou YC, Kuo SC, Chen CC, Hsu WJ, The Action Study Group, Chen HY, Sun JR. Ser253Leu substitution in PmrB contributes to colistin resistance in clinical Acinetobacter nosocomialis. Emerg Microbes Infect 2021; 10:1873-1880. [PMID: 34468294 PMCID: PMC8451652 DOI: 10.1080/22221751.2021.1976080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Infections caused by extensively drug-resistant (XDR) Acinetobacter nosocomialis have become a challenging problem. The frequent use of colistin as the last resort drug for XDR bacteria has led to the emergence of colistin-resistant A. nosocomialis (ColRAN) in hospitals. The mechanism of colistin resistance in A. nosocomialis remains unclear. This study aimed to investigate the mechanisms underlying colistin resistance in clinical ColRAN isolates. We collected 36 A. nosocomialis isolates from clinical blood cultures, including 24 ColRAN and 12 colistin-susceptible A. nosocomialis (ColSAN). The 24 ColRAN isolates clustered with ST1272 (13), ST433 (eight), ST1275 (two), and ST410 (one) by multilocus sequence typing. There was a positive relationship between pmrCAB operon expression and colistin resistance. Further analysis showed that colistin resistance was related to an amino acid substitution, Ser253Leu in PmrB. By introducing a series of recombinant PmrB constructs into a PmrB knockout strain and protein structural model analyses, we demonstrated that the association between Ser253Leu and Leu244 in PmrB was coupled with colistin resistance in ColRAN. To the best of our knowledge, this is the first study demonstrating that the key amino acid Ser253Leu in PmrB is associated with overexpression of the pmrCAB operon and hence colistin resistance. This study provides insight into the mechanism of colistin resistance in A. nosocomialis.
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Affiliation(s)
- Ya-Sung Yang
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Wen-Yih Jeng
- University Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan, Taiwan.,Department of Biochemistry and Molecular Biology, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Tzu Lee
- School of Medicine, National Yang-Ming University, Taipei, Taiwan.,Department of Emergency Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Chi-Ju Hsu
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Ching Chou
- School of Public Health, National Defense Medical Center, Taipei, Taiwan
| | - Shu-Chen Kuo
- National Institute of Infectious Diseases and Vaccinology, National Health Research Institutes, Zhunan, Taiwan
| | - Cheng-Cheung Chen
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan.,Graduate Institute of Medical Sciences, National Defence Medical Centre, Taipei, Taiwan
| | - Wei-Jane Hsu
- Department of Medical Techniques, Taipei City Hospital Ren-Ai Branch, Taipei, Taiwan
| | | | - Hsing-Yu Chen
- Department of Medical Techniques, Taipei City Hospital Ren-Ai Branch, Taipei, Taiwan
| | - Jun-Ren Sun
- Division of Infectious Diseases and Tropical Medicine, Department of Internal Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.,Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
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16
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Comparison of the Acinetobacter baumannii Reference Strains ATCC 17978 and ATCC 19606 in Antimicrobial Resistance Mediated by the AdeABC Efflux Pump. Antimicrob Agents Chemother 2021; 65:e0057021. [PMID: 34097477 DOI: 10.1128/aac.00570-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Acinetobacter baumannii RND efflux pump AdeABC is regulated by the 2-component regulator AdeRS. In this study, we compared the regulation and expression of AdeABC of the reference strains ATCC 17978 and ATCC 19606. A clearly stronger efflux activity was demonstrated for ATCC 19606. An amino acid substitution at residue 172 of adeS was identified as a potential cause for differential expression of the pump. Therefore, we recommend caution with exclusively using single reference strains for research.
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17
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Lucaßen K, Müller C, Wille J, Xanthopoulou K, Hackel M, Seifert H, Higgins PG. Prevalence of RND efflux pump regulator variants associated with tigecycline resistance in carbapenem-resistant Acinetobacter baumannii from a worldwide survey. J Antimicrob Chemother 2021; 76:1724-1730. [PMID: 33760099 DOI: 10.1093/jac/dkab079] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 02/18/2021] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To determine the most common tigecycline resistance mechanisms in carbapenem-resistant Acinetobacter baumannii isolates obtained during the global Tigecycline Evaluation Surveillance Trial (TEST). METHODS Tigecycline MICs were determined by broth microdilution. WGS was used to screen for the previously identified tigecycline resistance mechanisms, as well as mutations in resistance-nodulation-cell division (RND)-type efflux pump regulators. RESULTS From a total 313 isolates, 113 genetically unique tigecycline-resistant isolates were analysed. The most frequent and worldwide distributed mechanism associated with tigecycline resistance was disruption of adeN, which encodes the repressor of the RND efflux pump AdeIJK, either by IS elements or nucleotide deletions causing premature stop codons. However, mutations leading to amino acid substitutions and disruption by IS elements within the two-component regulatory system adeRS, which regulates expression of the AdeABC efflux pump, correlate with higher tigecycline MICs, but these were found less frequently and were mainly restricted to Southern European countries. Furthermore, an altered version of tviB was identified in several tigecycline-resistant isolates that did not have putative resistance mutations within RND-type regulators. The resistance determinants tet(A) and tet(X), as well as resistance mutations in putative resistance determinants trm, plsC, rrf, msbA and genes encoding 30S ribosomal proteins, were not identified in any isolate. CONCLUSIONS The most prevalent tigecycline resistance mechanisms were caused by alterations in the regulators of RND-type efflux pumps. These data provide the basis for further characterization of regulator alterations and their contribution to increased efflux and tigecycline resistance, and also should be taken into account in drug discovery programmes to overcome the contribution of efflux pumps.
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Affiliation(s)
- Kai Lucaßen
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany
| | - Carina Müller
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Julia Wille
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Kyriaki Xanthopoulou
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Meredith Hackel
- International Health Management Associates, 2122 Palmer Drive, Schaumburg, IL 60173, USA
| | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Paul G Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
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18
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Li L, Li R, Qi C, Gao H, Wei Q, Tan L, Sun F. Mechanisms of polymyxin resistance induced by Salmonella typhimurium in vitro. Vet Microbiol 2021; 257:109063. [PMID: 33932721 DOI: 10.1016/j.vetmic.2021.109063] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 03/29/2021] [Indexed: 11/26/2022]
Abstract
The increase incidence of multi-drug resistant (MDR) Salmonella has become a major global health concern. Polymyxin, an ancient polypeptide antibiotic, has been given renewed attention over recent years, resulting in resistance of Gram-negative bacteria to polymyxin, but its resistance mechanism is not completely clear. Thus, it is important to study its resistance mechanisms. In this study, an in vitro induced polymyxin-resistant strain of Salmonella typhimurium in the laboratory were constructed to investigate the mechanism of resistance of Salmonella to polymyxin. Gradual induction of Salmonella typhimurium ATCC13311 (AT) by concentration increment was used to screen for a highly polymyxin-resistant strain AT-P128. The broth dilution technique was used to compare the sensitivity of the two strains to different antimicrobial drugs. Single nucleotide polymorphisms (SNPs) were then identified by whole genome sequencing, and differences in gene expression between the two strains were compared by transcriptome sequencing and reverse transcription-quantitative PCR (RT-qPCR). Finally, for the first time, the CRISPR/Cas9 gene-editing system was used to construct gene deletion mutants in Salmonella to knock out the phoP gene of AT-P128. The results showed that strain AT-P128 was significantly more resistant to amoxicillin, ceftiofur, ampicillin, fluphenazine, and chloramphenicol and significantly less resistant to sulfamethoxazole than the parental strain AT. The growth curve results showed no significant change in the growth rate between AT-P128 and AT. Motility and biofilm formation assays showed a significant decrease in AT-P128. Additionally, the WGS results showed that AT-P128 had mutations in 9 genes involving 14 SNPs. RNA-seq and RT-qPCR results showed increased expression of phoPQ. The loss of the phoP gene decreased AT-P128ΔphoP resistance to polymyxin by 32-fold. These results suggested that polymyxin resistance affected the biology, genome components, and gene expression levels of Salmonella and that the PhoPQ two-component system played a key role in polymyxin resistance in Salmonella, providing insights into the diversity and complexity of polymyxin resistance in Salmonella.
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Affiliation(s)
- Lin Li
- Pharmacology and Toxicology Laboratory, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230026, PR China; Anhui Province Key Lab of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui 230036, PR China
| | - Rui Li
- Pharmacology and Toxicology Laboratory, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230026, PR China
| | - Caili Qi
- Pharmacology and Toxicology Laboratory, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230026, PR China
| | - Haixia Gao
- Pharmacology and Toxicology Laboratory, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230026, PR China
| | - Qiling Wei
- Pharmacology and Toxicology Laboratory, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230026, PR China
| | - Lei Tan
- Pharmacology and Toxicology Laboratory, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230026, PR China
| | - Feifei Sun
- Pharmacology and Toxicology Laboratory, College of Animal Science and Technology, Anhui Agricultural University, Hefei, Anhui 230026, PR China; Anhui Province Key Lab of Veterinary Pathobiology and Disease Control, Anhui Agricultural University, Hefei, Anhui 230036, PR China.
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19
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Carrasco LDDM, Dabul ANG, Boralli CMDS, Righetto GM, Carvalho ISE, Dornelas JV, Martins da Mata CPS, de Araújo CA, Leite EMM, Lincopan N, Camargo ILBDC. Polymyxin Resistance Among XDR ST1 Carbapenem-Resistant Acinetobacter baumannii Clone Expanding in a Teaching Hospital. Front Microbiol 2021; 12:622704. [PMID: 33897637 PMCID: PMC8063854 DOI: 10.3389/fmicb.2021.622704] [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: 10/29/2020] [Accepted: 03/05/2021] [Indexed: 12/14/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic pathogen primarily associated with multidrug-resistant nosocomial infections, for which polymyxins are the last-resort antibiotics. This study investigated carbapenem-resistant A. baumannii strains exhibiting an extensively drug-resistant (XDR) phenotype, including four isolates considered locally pan drug-resistant (LPDR), isolated from inpatients during an outbreak at a teaching hospital in Brazil. ApaI DNA macrorestriction followed by PFGE clustered the strains in three pulsotypes, named A to C, among carbapenem-resistant A. baumannii strains. Pulsotypes A and B clustered six polymyxin-resistant A. baumannii strains. MLST analysis of representative strains of pulsotypes A, B, and C showed that they belong, respectively, to sequence types ST1 (clonal complex, CC1), ST79 (CC79), and ST903. Genomic analysis of international clones ST1 and ST79 representative strains predicted a wide resistome for β-lactams, aminoglycosides, fluoroquinolones, and trimethoprim-sulfamethoxazole, with blaOXA–23 and blaOXA–72 genes encoding carbapenem resistance. Amino acid substitutions in PmrB (Thr232Ile or Pro170Leu) and PmrC (Arg125His) were responsible for polymyxin resistance. Although colistin MICs were all high (MIC ≥ 128 mg/L), polymyxin B MICs varied; strains with Pro170Leu substitution in PmrB had MICs > 128 mg/L, while those with Thr232Ile had lower MICs (16–64 mg/L), irrespective of the clone. Although the first identified polymyxin-resistant A. baumannii strain belonged to ST79, the ST1 strains were endemic and caused the outbreak most likely due to polymyxin B use. The genome comparison of two ST1 strains from the same patient, but one susceptible and the other resistant to polymyxin, revealed mutations in 28 ORFs in addition to pmrBC. The ORF codifying an acyl-CoA dehydrogenase has gained attention due to its fatty acid breakdown and membrane fluidity involvement. However, the role of these mutations in the polymyxin resistance mechanism remains unknown. To prevent the dissemination of XDR bacteria, the hospital infection control committee implemented the patient bathing practice with a 2% chlorhexidine solution, a higher concentration than all A. baumannii chlorhexidine MICs. In conclusion, we showed the emergence of polymyxin resistance due to mutations in the chromosome of the carbapenem-resistant A. baumannii ST1, a high-risk global clone spreading in this hospital.
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Affiliation(s)
- Letícia Dias de Melo Carrasco
- Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Paulo, Brazil
| | - Andrei Nicoli Gebieluca Dabul
- Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Paulo, Brazil
| | - Camila Maria Dos Santos Boralli
- Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Paulo, Brazil
| | - Gabriela Marinho Righetto
- Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Paulo, Brazil
| | - Iago Silva E Carvalho
- Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Paulo, Brazil
| | - Janaína Valerini Dornelas
- Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Paulo, Brazil
| | | | | | | | - Nilton Lincopan
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Ilana Lopes Baratella da Cunha Camargo
- Laboratory of Molecular Epidemiology and Microbiology, Department of Physics and Interdisciplinary Science, São Carlos Institute of Physics, University of São Paulo, São Paulo, Brazil
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20
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Sykes EME, Deo S, Kumar A. Recent Advances in Genetic Tools for Acinetobacter baumannii. Front Genet 2020; 11:601380. [PMID: 33414809 PMCID: PMC7783400 DOI: 10.3389/fgene.2020.601380] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/30/2020] [Indexed: 12/26/2022] Open
Abstract
Acinetobacter baumannii is classified as a top priority pathogen by the World Health Organization (WHO) because of its widespread resistance to all classes of antibiotics. This makes the need for understanding the mechanisms of resistance and virulence critical. Therefore, tools that allow genetic manipulations are vital to unravel the mechanisms of multidrug resistance (MDR) and virulence in A. baumannii. A host of current strategies are available for genetic manipulations of A. baumannii laboratory-strains, including ATCC® 17978TM and ATCC® 19606T, but depending on susceptibility profiles, these strategies may not be sufficient when targeting strains newly obtained from clinic, primarily due to the latter's high resistance to antibiotics that are commonly used for selection during genetic manipulations. This review highlights the most recent methods for genetic manipulation of A. baumannii including CRISPR based approaches, transposon mutagenesis, homologous recombination strategies, reporter systems and complementation techniques with the spotlight on those that can be applied to MDR clinical isolates.
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Affiliation(s)
- Ellen M E Sykes
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Soumya Deo
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
| | - Ayush Kumar
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada
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21
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Nodari CS, Cayô R, Streling AP, Lei F, Wille J, Almeida MS, de Paula AI, Pignatari ACC, Seifert H, Higgins PG, Gales AC. Genomic Analysis of Carbapenem-Resistant Acinetobacter baumannii Isolates Belonging to Major Endemic Clones in South America. Front Microbiol 2020; 11:584603. [PMID: 33329450 PMCID: PMC7734285 DOI: 10.3389/fmicb.2020.584603] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 11/04/2020] [Indexed: 12/17/2022] Open
Abstract
Carbapenem-resistant Acinetobacter baumannii (CRAB) are emerging worldwide. In South America, clinical isolates presenting such a phenotype usually do not belong to the globally distributed international clone 2 (IC2). The majority of these isolates are also resistant to multiple other antimicrobials and are often designated extremely drug-resistant (XDR). The aim of this study was to characterize the resistance mechanisms presented by 18 carbapenem-resistant A. baumannii isolates from five different Brazilian hospitals. Species identification was determined by rpoB sequencing, and antimicrobial susceptibility was determined by broth microdilution. Isolates were submitted to whole genome sequencing using Illumina platform and genetic similarity was determined by PFGE, MLST, and cgMLST. Genome analysis was used to identify intrinsic and acquired resistance determinants, including mutations in the AdeRSABC efflux system and in outer membrane proteins (OMPs). All isolates were identified as A. baumannii and grouped into 4 pulsotypes by PFGE, which belonged to clonal complexes (CC) 15Pas/103Ox (n = 4) and 79Pas/113Ox (n = 14), corresponding to IC4 and IC5, respectively. High MIC values to carbapenems, broad-spectrum cephalosporins, amikacin, and ciprofloxacin were observed in all isolates, while MICs of ampicillin/sulbactam, gentamicin, and tigecycline varied among the isolates. Minocycline was the most active antimicrobial agent tested. Moreover, 12 isolates (66.7%) were considered resistant to polymyxins. Besides intrinsic OXA-51 and ADC variants, all isolates harbored an acquired carbapenem-hydrolyzing class D β-lactamase (CHDL) encoding gene, either blaOXA–23 or blaOXA–72. A diversity of aminoglycoside modifying enzymes and resistance determinants to other antimicrobial classes were found, as well as mutations in gyrA and parC. Non-synonymous mutations have also been identified in the AdeRSABC efflux system and in most OMPs, but they were considered natural polymorphisms. Moreover, resistance to polymyxins among isolates belonging to IC5 were associated to non-synonymous mutations in pmrB, but no known polymyxin resistance mechanism was identified in isolates belonging to IC4. In conclusion, A. baumannii clinical isolates belonging to South America’s major clones present a myriad of antimicrobial resistance determinants. Special attention should be paid to natural polymorphisms observed in each clonal lineage, especially regarding non-synonymous mutations in constitutive genes associated with distinct resistance phenotypes.
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Affiliation(s)
- Carolina Silva Nodari
- Universidade Federal de São Paulo (UNIFESP), Laboratório Alerta, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil
| | - Rodrigo Cayô
- Universidade Federal de São Paulo (UNIFESP), Laboratório Alerta, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil.,Universidade Federal de São Paulo (UNIFESP), Laboratório de Imunologia e Bacteriologia (LIB), Setor de Biologia Molecular, Microbiologia e Imunologia - Departamento de Ciências Biológicas (DCB), Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF), Diadema, Brazil
| | - Ana Paula Streling
- Universidade Federal de São Paulo (UNIFESP), Laboratório Alerta, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil
| | - Felipe Lei
- Universidade Federal de São Paulo (UNIFESP), Laboratório Alerta, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil
| | - Julia Wille
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Myriam S Almeida
- Laboratório de Microbiologia, Hospital Universitário Cassiano Antônio de Moraes, Universidade Federal do Espírito Santo (UFES), Vitória, Brazil
| | - Alexandre Inacio de Paula
- Setor de Microbiologia - Serviço de Análises Clínicas, Hospital do Servidor Público Estadual (IAMSPE), São Paulo, Brazil
| | - Antonio Carlos Campos Pignatari
- Universidade Federal de São Paulo (UNIFESP), Laboratório Especial de Microbiologia Clínica (LEMC), Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil
| | - Harald Seifert
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Paul G Higgins
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Cologne, Germany
| | - Ana Cristina Gales
- Universidade Federal de São Paulo (UNIFESP), Laboratório Alerta, Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil.,Universidade Federal de São Paulo (UNIFESP), Laboratório Especial de Microbiologia Clínica (LEMC), Division of Infectious Diseases, Department of Internal Medicine, Escola Paulista de Medicina (EPM), São Paulo, Brazil
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22
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Lunha K, Thet KT, Ngudsuntia A, Charoensri N, Lulitanond A, Tavichakorntrakool R, Wonglakorn L, Faksri K, Chanawong A. PmrB mutations including a novel 10-amino acid repeat sequence insertion associated with low-level colistin resistance in carbapenem-resistant Acinetobacter baumannii. INFECTION GENETICS AND EVOLUTION 2020; 85:104577. [PMID: 33007498 DOI: 10.1016/j.meegid.2020.104577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 09/22/2020] [Accepted: 09/27/2020] [Indexed: 10/23/2022]
Abstract
The global emergence of colistin resistance in carbapenem-resistant Acinetobacter baumannii (CRAB) clinical isolates is a serious public health concern. We therefore aimed to investigate colistin resistance mechanisms in 5 colistin-resistant (COL-R) CRAB isolates collected from Thai patients in 2016 by whole genome sequencing (WGS) compared with those of 5 colistin-intermediate (COL-I) CRAB isolates from the same period. All isolates were subjected to antimicrobial susceptibility testing, efflux pump inhibitor-based test and WGS. Mutations in known genes associated with colistin resistance were analyzed and deleterious mutations were then predicted by PROVEAN tool. The 10 CRAB isolates carried blaOXA-23 with the addition of blaOXA-58 in 1 isolate. All COL-R isolates exhibited colistin MICs of 4 μg/mL except for 1 isolate with that of 16 μg/mL. They belonged to ST2, ST16, ST23, ST164 and ST215, whereas the COL-I isolates with colistin MICs of ≤0.25-1 μg/mL were ST2, ST164 and ST215. Neither increased efflux pump activity nor mcr gene was found in any COL-R isolate. Three COL-R isolates contained different PmrB variants: a novel 10-amino acid (aa) repeat sequence insertion, VILGCILIFS between positions 27 and 28 (S27_A28insVILGCILIFS) in transmembrane domain (TM); a 1-aa insertion, alanine between positions 162 and 163 (A162_I163insA) in TM; and a 1-aa substitution, A226T in histidine kinase domain. One COL-R isolate possessed PmrA variant with A80V substitution. These alterations were predicted as deleterious. Mechanisms of colistin resistance in the remaining COL-R isolate were still unknown. In conclusion, the alterations in both PmrB and PmrA were predicted and suggested as initial mutations responsible for low-level colistin resistance in our CRAB isolates. Under selective pressure, these isolates may exhibit higher level colistin resistance by the additional mutations, leading to more therapeutic difficulties.
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Affiliation(s)
- Kamonwan Lunha
- Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Khin Thet Thet
- Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Arisa Ngudsuntia
- Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Nicha Charoensri
- Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Aroonlug Lulitanond
- Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Ratree Tavichakorntrakool
- Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Lumyai Wonglakorn
- Clinical Microbiology Laboratory, Srinagarind Hospital, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Kiatichai Faksri
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Aroonwadee Chanawong
- Centre for Research and Development of Medical Diagnostic Laboratories (CMDL), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
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23
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Palmieri M, D’Andrea MM, Pelegrin AC, Perrot N, Mirande C, Blanc B, Legakis N, Goossens H, Rossolini GM, van Belkum A. Abundance of Colistin-Resistant, OXA-23- and ArmA-Producing Acinetobacter baumannii Belonging to International Clone 2 in Greece. Front Microbiol 2020; 11:668. [PMID: 32425900 PMCID: PMC7212473 DOI: 10.3389/fmicb.2020.00668] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/24/2020] [Indexed: 12/14/2022] Open
Abstract
Carbapenem resistant Acinetobacter baumannii (CRAB) represents one of the most challenging pathogens in clinical settings. Colistin is routinely used for treatment of infections by this pathogen, but increasing colistin resistance has been reported. We obtained 122 CRAB isolates from nine Greek hospitals between 2015 and 2017, and those colistin resistant (ColR; N = 40, 32.8%) were whole genome sequenced, also by including two colistin susceptible (ColS) isolates for comparison. All ColR isolates were characterized by a previously described mutation, PmrBA226V, which was associated with low-level colistin resistance. Some isolates were characterized by additional mutations in PmrB (E140V or L178F) or PmrA (K172I or D10N), first described here, and higher colistin minimum inhibitory concentrations (MICs), up to 64 mg/L. Mass spectrometry analysis of lipid A showed the presence of a phosphoethanolamine (pEtN) moiety on lipid A, likely resulting from the PmrA/B-induced pmrC overexpression. Interestingly, also the two ColS isolates had the same lipid A modification, suggesting that not all lipid A modifications lead to colistin resistance or that other factors could contribute to the resistance phenotype. Most of the isolates (N = 37, 92.5%) belonged to the globally distributed international clone (IC) 2 and comprised four different sequence types (STs) as defined by using the Oxford scheme (ST 425, 208, 451, and 436). Three isolates belonged to IC1 and ST1567. All the genomes harbored an intrinsic bla OXA-51 group carbapenemase gene, where bla OXA-66 and bla OXA-69 were associated with IC2 and IC1, respectively. Carbapenem resistance was due to the most commonly reported acquired carbapenemase gene bla OXA-23, with ISAba1 located upstream of the gene and likely increasing its expression. The armA gene, associated with high-level resistance to aminoglycosides, was detected in 87.5% of isolates. Collectively, these results revealed a convergent evolution of different clonal lineages toward the same colistin resistance mechanism, thus limiting the effective therapeutic options for the treatment of CRAB infections.
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Affiliation(s)
- Mattia Palmieri
- bioMérieux, Data Analytics Unit, La Balme-les-Grottes, France
| | - Marco Maria D’Andrea
- Department of Medical Biotechnologies, University of Siena, Siena, Italy
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
| | | | - Nadine Perrot
- bioMérieux, R&D Microbiology, La Balme-les-Grottes, France
| | | | | | | | - Herman Goossens
- Laboratory of Medical Microbiology, Vaccine and Infectious Disease Institute, University of Antwerp, Antwerp, Belgium
| | - Gian Maria Rossolini
- Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy
- Clinical Microbiology and Virology Unit, Florence Careggi University Hospital, Florence, Italy
| | - Alex van Belkum
- bioMérieux, Data Analytics Unit, La Balme-les-Grottes, France
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