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Kim SJ, Jo J, Ko KS. Lipid A modification-induced colistin-resistant Klebsiella variicola from healthy adults. J Med Microbiol 2023; 72. [PMID: 37261959 DOI: 10.1099/jmm.0.001680] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023] Open
Abstract
Background. Klebsiella variicola was once recognised as a benign plant-endosymbiont but recent case reports suggest that it is a newly emerging Gram-negative pathogen related to opportunistic infection of multiple sites in humans.Methods. Antimicrobial susceptibility testing was performed using broth microdilution method. To identify colistin resistance mechanisms, phoPQ, pmrAB, and mgrB were sequenced and their mRNA expression was analysed using quantitative real-time PCR. In addition, we tried to detect crrAB and mcr. The lipid A moieties of colistin-susceptible and -resistant isolates were analysed using MALDI-TOF.Results. Among the two K. variicola isolates, one is colistin-resistant, and another is colistin-susceptible. The colistin-resistant K. variicola isolate showed no mutations in phoPQ, pmrAB, and mgrB, and crrAB and mcr were not identified. However, its phoQ and pbgP expression was significantly higher and amino-arabinosylated lipid A with hexa-acylated species in lipopolysaccharide was identified.Conclusions. We found that colistin resistance in K. variicola was mediated by the modification of lipid A. Although the isolate was obtained from faecal samples of healthy adults, colistin-resistant K. variicola challenges public health as an opportunistic pathogen.
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Affiliation(s)
- Sun Ju Kim
- Department of Pharmacy, School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
| | - Jeongwoo Jo
- Department of Microbiology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Kwan Soo Ko
- Department of Microbiology, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
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Prevalence of Mutated Colistin-Resistant Klebsiella pneumoniae: A Systematic Review and Meta-Analysis. Trop Med Infect Dis 2022; 7:tropicalmed7120414. [PMID: 36548669 PMCID: PMC9782491 DOI: 10.3390/tropicalmed7120414] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/04/2022] Open
Abstract
The emergence of genetic mutations in chromosomal genes and the transmissible plasmid-mediated colistin resistance gene may have helped in the spread of colistin resistance among various Klebsiella pneumoniae (K. pneumoniae) isolates and other different bacteria. In this study, the prevalence of mutated colistin-resistant K. pneumoniae isolates was studied globally using a systematic review and meta-analysis approach. A systematic search was conducted in databases including PubMed, ScienceDirect, Scopus and Google Scholar. The pooled prevalence of mutated colistin resistance in K. pneumoniae isolates was analyzed using Comprehensive Meta-Analysis Software (CMA). A total of 50 articles were included in this study. The pooled prevalence of mutated colistin resistance in K. pneumoniae was estimated at 75.4% (95% CI = 67.2−82.1) at high heterogeneity (I2 = 81.742%, p-value < 0.001). Meanwhile, the results of the subgroup analysis demonstrated the highest prevalence in Saudi Arabia with 97.9% (95% CI = 74.1−99.9%) and Egypt, with 4.5% (95% CI = 0.6−26.1%), had the lowest. The majority of mutations could be observed in the mgrB gene (88%), pmrB gene (54%) and phoQ gene (44%). The current study showed a high prevalence of the mutation of colistin resistance genes in K. pneumoniae. Therefore, it is recommended that regular monitoring be performed to control the spread of colistin resistance.
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Kim SJ, Cho H, Ko KS. Comparative analysis of the Colistin resistance-regulating gene cluster in Klebsiella species. J Microbiol 2022; 60:461-468. [DOI: 10.1007/s12275-022-1640-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 01/18/2022] [Accepted: 01/20/2022] [Indexed: 10/18/2022]
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Seo J, Wi YM, Kim JM, Kim YJ, Ko KS. Detection of colistin-resistant populations prior to antibiotic exposure in KPC-2-producing Klebsiella pneumoniae clinical isolates. J Microbiol 2021; 59:590-597. [PMID: 33779958 DOI: 10.1007/s12275-021-0610-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 01/26/2021] [Accepted: 02/09/2021] [Indexed: 12/12/2022]
Abstract
Although colistin is frequently regarded as the antibiotic of last resort in treating carbapenem-resistant Klebsiella pneumoniae, colistin heteroresistance may in part be associated with antibiotic treatment failure. However, we do not know how widespread the colistin heteroresistance is in carbapenem-resistant K. pneumoniae isolates. In this study, we performed colistin disc diffusion assays, E-tests, and population analysis profiling for KPC-2-producing K. pneumoniae isolates to identify colistin heteroresistance. Although no colistin-resistant colonies were detected by the disc diffusion test and E-test, a colistin-resistant subpopulation was identified in population analysis profiling in all colistin-susceptible, KPC-2-producing K. pneumoniae isolates. Colistin-resistant subpopulations were also identified even when isolates had no colistin exposure. The ratio of colistin-resistant subpopulations to the total population increased as the exposure concentration of colistin increased. In in vitro time-kill assays, regrowth was observed in all isolates after 2 h upon exposure to colistin. We identified common amino acid alterations in PhoQ, PhoP, and PmrB in colistin-resistant subpopulations from some isolates, but no substitutions were found in most resistant subpopulations from other isolates. In all colistin-resistant subpopulations, overexpression of PhoQ and PbgP was observed. In this study, we demonstrated that colistin heteroresistance may be common in KPC-2-producing K. pneumoniae isolates, which could not be detected in the disc diffusion method and E-test. Colistin heteroresistance may cause colistin treatment failure in part and may evolve into resistance. Thus, development of more reliable diagnostic methods is required to detect colistin heteroresistance.
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Affiliation(s)
- Jungyu Seo
- Department of Microbiology and Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea
| | - Yu Mi Wi
- Division of Infectious Diseases, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, 51353, Republic of Korea
| | - Jong Min Kim
- Department of Pediatrics, Myongji Hospital, Goyang, 10475, Republic of Korea
| | - Yae-Jean Kim
- Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06355, Republic of Korea
| | - Kwan Soo Ko
- Department of Microbiology and Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea.
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Risk factors and mechanisms of in vivo emergence of colistin resistance in carbapenem-resistant Klebsiella pneumoniae. Int J Antimicrob Agents 2021; 57:106342. [PMID: 33864932 DOI: 10.1016/j.ijantimicag.2021.106342] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 03/07/2021] [Accepted: 04/03/2021] [Indexed: 11/21/2022]
Abstract
Colistin is one of the last-resort antibiotics for treating carbapenem-resistant Klebsiella pneumoniae (CRKP). However, colistin resistance in CRKP poses a global antimicrobial crisis, as therapeutic options are limited. We investigated risk factors for in vivo emergence of colistin resistance in CRKP and explored the underlying resistance mechanisms. We conducted this matched case-control study of patients with sequential CRKP clinical strains at a medical centre in Taiwan between October 2016 and June 2019. The case group included patients with an index colistin-resistant CRKP (ColR-CRKP) strain and a previous colistin-susceptible CRKP (ColS-CRKP) counterpart. The control group encompassed patients with both an index and previous ColS-CRKP strains. Cases and controls were matched according to the time at risk, and conditional logistic regression was used to evaluate potential risk factors. Alterations in genes associated with resistance were compared between ColR-CRKP and ColS-CRKP strains. We identified 24 CRKP cases with in vivo-emergent colistin resistance, matched in a 1:2 ratio with controls. Multivariate analysis showed that colistin exposure is the only independent risk factor predisposing to colistin resistance (adjusted odds ratio = 19.09, 95% confidence interval 1.26-290.45; P = 0.034). Alteration in the mgrB gene was the predominant mechanism for emergent colistin resistance (17/24; 71%). In conclusion, colistin use is a risk factor for in vivo emergence of colistin resistance in CRKP. Given the lack of a rapid and reliable method to detect colistin resistance in daily practice, physicians should be vigilant for the emergence of resistance during colistin treatment.
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Aulin LBS, Koumans CIM, Haakman Y, van Os W, Kraakman MEM, Gooskens J, Smits WK, Liakopoulos A, van Hasselt JGC. Distinct evolution of colistin resistance associated with experimental resistance evolution models in Klebsiella pneumoniae. J Antimicrob Chemother 2021; 76:533-535. [PMID: 33150358 PMCID: PMC7816166 DOI: 10.1093/jac/dkaa450] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/30/2020] [Indexed: 12/04/2022] Open
Affiliation(s)
- L B S Aulin
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - C I M Koumans
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Y Haakman
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - W van Os
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - M E M Kraakman
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - J Gooskens
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - W K Smits
- Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - A Liakopoulos
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - J G C van Hasselt
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
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Emerging Transcriptional and Genomic Mechanisms Mediating Carbapenem and Polymyxin Resistance in Enterobacteriaceae: a Systematic Review of Current Reports. mSystems 2020; 5:5/6/e00783-20. [PMID: 33323413 PMCID: PMC7771540 DOI: 10.1128/msystems.00783-20] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The spread of carbapenem- and polymyxin-resistant Enterobacteriaceae poses a significant threat to public health, challenging clinicians worldwide with limited therapeutic options. This review describes the current coding and noncoding genetic and transcriptional mechanisms mediating carbapenem and polymyxin resistance, respectively. The spread of carbapenem- and polymyxin-resistant Enterobacteriaceae poses a significant threat to public health, challenging clinicians worldwide with limited therapeutic options. This review describes the current coding and noncoding genetic and transcriptional mechanisms mediating carbapenem and polymyxin resistance, respectively. A systematic review of all studies published in PubMed database between 2015 to October 2020 was performed. Journal articles evaluating carbapenem and polymyxin resistance mechanisms, respectively, were included. The search identified 171 journal articles for inclusion. Different New Delhi metallo-β-lactamase (NDM) carbapenemase variants had different transcriptional and affinity responses to different carbapenems. Mutations within the Klebsiella pneumoniae carbapenemase (KPC) mobile transposon, Tn4401, affect its promoter activity and expression levels, increasing carbapenem resistance. Insertion of IS26 in ardK increased imipenemase expression 53-fold. ompCF porin downregulation (mediated by envZ and ompR mutations), micCF small RNA hyperexpression, efflux upregulation (mediated by acrA, acrR, araC, marA, soxS, ramA, etc.), and mutations in acrAB-tolC mediated clinical carbapenem resistance when coupled with β-lactamase activity in a species-specific manner but not when acting without β-lactamases. Mutations in pmrAB, phoPQ, crrAB, and mgrB affect phosphorylation of lipid A of the lipopolysaccharide through the pmrHFIJKLM (arnBCDATEF or pbgP) cluster, leading to polymyxin resistance; mgrB inactivation also affected capsule structure. Mobile and induced mcr, efflux hyperexpression and porin downregulation, and Ecr transmembrane protein also conferred polymyxin resistance and heteroresistance. Carbapenem and polymyxin resistance is thus mediated by a diverse range of genetic and transcriptional mechanisms that are easily activated in an inducing environment. The molecular understanding of these emerging mechanisms can aid in developing new therapeutics for multidrug-resistant Enterobacteriaceae isolates.
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Colistin Heteroresistance among Extended Spectrum β-lactamases-Producing Klebsiella pneumoniae. Microorganisms 2020; 8:microorganisms8091279. [PMID: 32825799 PMCID: PMC7569871 DOI: 10.3390/microorganisms8091279] [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: 07/29/2020] [Revised: 08/14/2020] [Accepted: 08/20/2020] [Indexed: 01/24/2023] Open
Abstract
Colistin-heteroresistant (CST-HR) Enterobacterales isolates have been identified recently, challenging the clinical laboratories since routine susceptibility tests fail to detect this phenotype. In this work we describe the first CST-HR phenotype in extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolates in South America. Additionally, we determine the genomic mechanisms of colistin heteroresistance in these strains. The CST-HR phenotype was analyzed by the population analysis profile (PAP) method, and mutations associated with this phenotype were determined by whole-genome sequencing (WGS) and the local BLAST+ DB tool. As a result, 8/60 isolates were classified as CST-HR according to the PAP method. From WGS, we determined that the CST-HR isolates belong to three different Sequence Types (STs) and four K-loci: ST11 (KL15 and KL81), ST25 (KL2), and ST1161 (KL19). We identified diverse mutations in the two-component regulatory systems PmrAB and PhoPQ, as well as a disruption of the mgrB global regulator mediated by IS1-like and IS-5-like elements, which could confer resistance to CST in CST-HR and ESBL-producing isolates. These are the first descriptions in Chile of CST-HR in ESBL-producing K. pneumoniae isolates. The emergence of these isolates could have a major impact on the effectiveness of colistin as a “last resort” against these isolates, thus jeopardizing current antibiotic alternatives; therefore, it is important to consider the epidemiology of the CST-HR phenotype.
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Choi M, Ko KS. Identification of Genetic Alterations Associated with Acquired Colistin Resistance in Klebsiella pneumoniae Isogenic Strains by Whole-Genome Sequencing. Antibiotics (Basel) 2020; 9:antibiotics9070374. [PMID: 32630683 PMCID: PMC7400116 DOI: 10.3390/antibiotics9070374] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 06/25/2020] [Accepted: 06/30/2020] [Indexed: 11/16/2022] Open
Abstract
The present study was undertaken to find novel genes associated with colistin resistance in Klebsiella pneumoniae. Five colistin-resistant mutants were derived from four colistin-susceptible parental K. pneumoniae strains belonging to different clones. Whole-genome sequencing was performed for the nine K. pneumoniae strains to screen altered candidate genes. Expression levels of genes with amino acid alterations in derivative strains were determined using quantitative real-time Polymerase chain reaction (PCR). Colistin susceptibility was examined in a parental strain complemented with altered candidate genes. Overall, 13 genetic alterations were identified in five pairs of isogenic K. pneumoniae strains. Genetic alterations related to KP1_3468, including the insertion of an IS5-like element in an intergenic or coding region and amino acid substitutions, were identified in three separate derivative strains. Amino acid substitutions and deletion of PhoQ were determined in one derivative strain. With inactivation of CrrA and substituted CrrB, amino acid substitutions and deletion were identified in a repressor of galETK operon (KP1_0061) and hypothetical protein (KP1_3620), respectively. Decreased colistin susceptibility was observed in a parental strain complemented with KP1-0061, but not a KP1-3620 gene. This study demonstrated diverse genetic paths to colistin resistance in K. pneumoniae. Our results suggest that a repressor of galETK operon may play an important role in colistin resistance in K. pneumoniae.
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Affiliation(s)
| | - Kwan Soo Ko
- Correspondence: ; Tel.: +82-31-299-6223; Fax: +82-31-299-6229
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Cheong HS, Kim SY, Seo J, Wi YM, Peck KR, Ko KS. Colistin Resistance and Extensive Genetic Variations in PmrAB and PhoPQ in Klebsiella Pneumoniae Isolates from South Korea. Curr Microbiol 2020; 77:2307-2311. [PMID: 32524274 DOI: 10.1007/s00284-020-02074-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 06/03/2020] [Indexed: 12/22/2022]
Abstract
We investigated the colistin resistance of Klebsiella pneumoniae blood isolates from South Korea. Among 252 K. pneumoniae isolates, only 11 (4.4%) demonstrated colistin resistance, of which, one was resistant to all antibiotics but tigecycline. Multilocus sequence typing analysis revealed ten sequence types among the 11 colistin-resistant isolates, indicating independent occurrence of colistin resistance in K. pneumoniae. To understand the mechanism of colistin resistance, amino acid variations in PmrAB, PmrD, PhoPQ, and MgrB were investigated. Amino acid substitutions were identified in all the colistin-resistant K. pneumoniae isolates. Particularly, extensive alterations in the genes associated with colistin resistance were shared in four colistin-resistant isolates, suggesting recombination between these genes of unrelated isolates. Our results suggest that genetic recombination is responsible for colistin resistance in some K. pneumoniae isolates.
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Affiliation(s)
- Hae Suk Cheong
- Division of Infectious Disease, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, 03181, Republic of Korea
| | - So Yeon Kim
- Division of Bacterial Disease Research, Center for Infectious Diseases Research, Centers for Control and Prevention, Korea National Institute of Health, Cheongju, 28159, Republic of Korea
| | - Jungyu Seo
- Department of Microbiology, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea
| | - Yu Mi Wi
- Division of Infectious Diseases, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, 51353, Republic of Korea
| | - Kyong Ran Peck
- Division of Infectious Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, Republic of Korea
| | - Kwan Soo Ko
- Department of Microbiology, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea.
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Huang J, Li C, Song J, Velkov T, Wang L, Zhu Y, Li J. Regulating polymyxin resistance in Gram-negative bacteria: roles of two-component systems PhoPQ and PmrAB. Future Microbiol 2020; 15:445-459. [PMID: 32250173 DOI: 10.2217/fmb-2019-0322] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Polymyxins (polymyxin B and colistin) are last-line antibiotics against multidrug-resistant Gram-negative pathogens. Polymyxin resistance is increasing worldwide, with resistance most commonly regulated by two-component systems such as PmrAB and PhoPQ. This review discusses the regulatory mechanisms of PhoPQ and PmrAB in mediating polymyxin resistance, from receiving an external stimulus through to activation of genes responsible for lipid A modifications. By analyzing the reported nonsynonymous substitutions in each two-component system, we identified the domains that are critical for polymyxin resistance. Notably, for PmrB 71% of resistance-conferring nonsynonymous mutations occurred in the HAMP (present in histidine kinases, adenylate cyclases, methyl accepting proteins and phosphatase) linker and DHp (dimerization and histidine phosphotransfer) domains. These results enhance our understanding of the regulatory mechanisms underpinning polymyxin resistance and may assist with the development of new strategies to minimize resistance emergence.
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Affiliation(s)
- Jiayuan Huang
- Biomedicine Discovery Institute & Department of Microbiology, Monash University, Melbourne 3800, Australia
| | - Chen Li
- Biomedicine Discovery Institute & Department of Biochemistry & Molecular Biology, Monash University, Melbourne 3800, Australia.,Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich 8093, Switzerland
| | - Jiangning Song
- Biomedicine Discovery Institute & Department of Biochemistry & Molecular Biology, Monash University, Melbourne 3800, Australia
| | - Tony Velkov
- Department of Pharmacology & Therapeutics, School of Biomedical Sciences, Faculty of Medicine, Dentistry & Health Sciences, The University of Melbourne, Melbourne 3010, Australia
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao 266237, China
| | - Yan Zhu
- Biomedicine Discovery Institute & Department of Microbiology, Monash University, Melbourne 3800, Australia
| | - Jian Li
- Biomedicine Discovery Institute & Department of Microbiology, Monash University, Melbourne 3800, Australia
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12
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Hong YK, Ko KS. PmrAB and PhoPQ Variants in Colistin-Resistant Enterobacter spp. Isolates in Korea. Curr Microbiol 2019; 76:644-649. [PMID: 30891622 DOI: 10.1007/s00284-019-01672-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 03/13/2019] [Indexed: 12/18/2022]
Abstract
In this study, we investigated the amino acid variations and mRNA expression of PhoPQ and PmrAB two-component regulatory systems in colistin-resistant Enterobacter cloacae isolates from Korea. We determined the nucleotide sequences of phoP, phoQ, pmrA, and pmrB in 51 colistin-resistant, 5 colistin-susceptible, and 8 skip-well isolates and consequently, the corresponding amino acid sequences as well. PhoPQ and PmrAB sequences showed large variations among the isolates (14, 67, 20, and 68 sites, respectively). Although there was some discrepancy between the genes, the colistin-resistant E. cloacae isolates were grouped into four clades and the susceptible isolates were grouped into two clades. We did not find any distinct amino acid substitutions associated with colistin resistance. Furthermore, mRNA expression of phoQ and pmrB was not significantly higher in the colistin-resistant isolates. Our data suggests that the colistin resistance mechanisms might be different in E. cloacae when compared to other gram-negative bacteria.
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Affiliation(s)
- Yoon-Kyoung Hong
- Department of Molecular Cell Biology and Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea
| | - Kwan Soo Ko
- Department of Molecular Cell Biology and Samsung Medical Center, Sungkyunkwan University School of Medicine, Suwon, 16419, Republic of Korea.
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Hashemi MM, Holden BS, Coburn J, Taylor MF, Weber S, Hilton B, Zaugg AL, McEwan C, Carson R, Andersen JL, Price JC, Deng S, Savage PB. Proteomic Analysis of Resistance of Gram-Negative Bacteria to Chlorhexidine and Impacts on Susceptibility to Colistin, Antimicrobial Peptides, and Ceragenins. Front Microbiol 2019; 10:210. [PMID: 30833936 PMCID: PMC6388577 DOI: 10.3389/fmicb.2019.00210] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 01/24/2019] [Indexed: 12/19/2022] Open
Abstract
Use of chlorhexidine in clinical settings has led to concerns that repeated exposure of bacteria to sub-lethal doses of chlorhexidine might result in chlorhexidine resistance and cross resistance with other cationic antimicrobials including colistin, endogenous antimicrobial peptides (AMPs) and their mimics, ceragenins. We have previously shown that colistin-resistant Gram-negative bacteria remain susceptible to AMPs and ceragenins. Here, we investigated the potential for cross resistance between chlorhexidine, colistin, AMPs and ceragenins by serial exposure of standard strains of Gram-negative bacteria to chlorhexidine to generate resistant populations of organisms. Furthermore, we performed a proteomics study on the chlorhexidine-resistant strains and compared them to the wild-type strains to find the pathways by which bacteria develop resistance to chlorhexidine. Serial exposure of Gram-negative bacteria to chlorhexidine resulted in four- to eight-fold increases in minimum inhibitory concentrations (MICs). Chlorhexidine-resistant organisms showed decreased susceptibility to colistin (8- to 32-fold increases in MICs) despite not being exposed to colistin. In contrast, chlorhexidine-resistant organisms had the same MICs as the original strains when tested with representative AMPs (LL-37 and magainin I) and ceragenins (CSA-44 and CSA-131). These results imply that there may be a connection between the emergence of highly colistin-resistant Gram-negative pathogens and the prevalence of chlorhexidine usage. Yet, use of chlorhexidine may not impact innate immune defenses (e.g., AMPs) and their mimics (e.g., ceragenins). Here, we also show that chlorhexidine resistance is associated with upregulation of proteins involved in the assembly of LPS for outer membrane biogenesis and virulence factors in Pseudomonas aeruginosa. Additionally, resistance to chlorhexidine resulted in elevated expression levels of proteins associated with chaperones, efflux pumps, flagella and cell metabolism. This study provides a comprehensive overview of the evolutionary proteomic changes in P. aeruginosa following exposure to chlorhexidine and colistin. These results have important clinical implications considering the continuous application of chlorhexidine in hospitals that could influence the emergence of colistin-resistant strains.
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Affiliation(s)
- Marjan M Hashemi
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Brett S Holden
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Jordan Coburn
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Maddison F Taylor
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Scott Weber
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Brian Hilton
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Aaron L Zaugg
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Colten McEwan
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Richard Carson
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Joshua L Andersen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - John C Price
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Shenglou Deng
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
| | - Paul B Savage
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, United States
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