Microbial drug resistance最新文献

{"title":"Occurrence of <i>bla</i>_OXA-116 Carbapenemase in <i>Escherichia coli</i> ST2519 of Clinical Origin: A Report from Northeast India.","authors":"Bhaskar Jyoti Das, K Melson Singha, Jayalaxmi Wangkheimayum, Debadatta Dhar Chanda, Amitabha Bhattacharjee","doi":"10.1089/mdr.2024.0022","DOIUrl":"10.1089/mdr.2024.0022","url":null,"abstract":"<p><p>Carbapenem-resistant <i>Escherichia coli</i> pose a significant threat to global public health due to the dearth of available treatment options, resulting in infections with high mortality and morbidity. The study aimed to investigate the mechanism of carbapenem resistance in a carbapenem non-susceptible <i>E. coli</i> isolate recovered from an urinary tract infection patient admitted to a tertiary referral hospital, through whole-genome sequencing using Illumina NovaSeq 6000 platform. Carbapenemase production followed by antibiotic susceptibility testing were performed following Clinical Laboratory Standard Institute guidelines. Polymerase chain reaction targeting carbapenemase genes was performed followed by an investigation of horizontal transferability. The Center for Genomic Epidemiology database was used to analyze the sequenced data. ST2519 <i>E. coli</i> BJD_EC1808 with a genome size of 5.8 Mb harbored Col440I plasmid and a chromosomally located <i>bla</i>_OXA-116 gene with an IS18 element upstream, along with multiple antibiotic resistance genes conferring clinical resistance toward beta-lactams, aminoglycosides, amphenicols, sulfonamides, tetracyclines, trimethoprim, rifampin, macrolide, and streptogramin antibiotics and antiseptics. <i>E. coli</i> ST2519 harboring <i>bla</i>_OXA-116 associated with a mobile genetic element exhibiting carbapenem resistance is a public health threat due to its limiting effect on the therapeutic usage of carbapenem and their dissemination into carbapenem non-susceptible phenotypes will contribute to carbapenem resistance burden and, therefore, warrants urgent monitoring and clinical intervention.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"399-406"},"PeriodicalIF":2.3,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141879139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining the Disinfectants Resistance Genes and the Susceptibility to Common Disinfectants of Extensively Drug-Resistant Carbapenem-Resistant <i>Klebsiella pneumoniae</i> Strains at a Tertiary Hospital in China.","authors":"Kexin Zhao, Liang Wang, Jinglan Deng, Qiuxia Zuo, Maimaiti Adila, Xiao Wang, Zhe Dai, Ping Tian","doi":"10.1089/mdr.2024.0089","DOIUrl":"10.1089/mdr.2024.0089","url":null,"abstract":"<p><p>Carbapenem-resistant <i>Klebsiella pneumoniae</i> (CRKP) infection has become a significant threat to global health. The application of chemical disinfectants is an effective infection control strategy to prevent the spread of CRKP in hospital environments. However, bacteria have shown reduced sensitivity to clinical disinfectants in recent years. Furthermore, bacteria can acquire antibiotic resistance due to the induction of disinfectants, posing a considerable challenge to hospital infection prevention and control. This study collected 68 CRKP strains from the Fifth Affiliated Hospital of Xinjiang Medical University in China from 2023 to 2024. These strains were isolated from the sputum, urine, and whole blood samples of patients diagnosed with CRKP infection. Antibiotic susceptibility tests were performed on CRKP strains. Concurrently, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of disinfectants (benzalkonium bromide, 1% iodophor disinfectant, alcohol, and chlorine-containing disinfectant) against the test isolates were determined by the broth microdilution method. The efflux pump genes (cepA, qacE, qacEΔ1, qacEΔ1-SUL1, oqxA, and oqxB) were detected using polymerase chain reaction. The results showed that 21 out of the 68 CRKP strains exhibited extensive drug resistance, whereas 47 were nonextensively drug-resistant. The MIC value for benzalkonium bromide disinfectants displayed statistically significant differences (<i>p</i> < 0.05) between extensively drug-resistant (XDR) and non-XDR strains. Additionally, the MBC values for benzalkonium bromide disinfectants and 1% iodophor disinfectants displayed statistically significant differences (<i>p</i> < 0.05) between XDR and non-XDR strains. The detection rates for the efflux pump genes were as follows: cepA 52.9%, qacE 39.7%, qacEΔ1 35.2%, qacEΔ1-SUL1 52.9%, oqxA 30.8%, and oqxB 32.3%. The detection rate of the qacEΔ1-SUL1 gene in XDR CRKP strains was significantly higher than in non-XDR CRKP strains (<i>p</i> < 0.05). This indicates a potential link between CRKP bacterial disinfectant efflux pump genes and CRKP bacterial resistance patterns. Ongoing monitoring of the declining sensitivity of XDR strains against disinfectants is essential for the effective control and prevention of superbug.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"407-414"},"PeriodicalIF":2.3,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142009075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in the Antimicrobial Resistance and Bacterial Epidemiology of <i>Moraxella catarrhalis</i> from Pediatric Community-Acquired Pneumonia Patients During the COVID-19 Pandemic: A 5-Year Study at a Tertiary Hospital of Southwest China.","authors":"Ling Ai, Chanjuan Zhou, Beizhong Liu, Liang Fang, Fang Gong","doi":"10.1089/mdr.2024.0064","DOIUrl":"10.1089/mdr.2024.0064","url":null,"abstract":"<p><p>This study aimed to assess the impact of the COVID-19 pandemic on <i>Moraxella catarrhalis</i> infections in pediatric patients hospitalized with community-acquired pneumonia (CAP). The epidemiological features and antimicrobial resistance (AMR) patterns of <i>M. catarrhalis</i> were compared between the pre-pandemic period (2018-2019) and during the pandemic (2020-2022). The results revealed a marked increase in the positivity rate of <i>M. catarrhalis</i> in 2020 and 2021 compared with the pre-pandemic years. The median age of the patients increased significantly in 2021 and 2022, while the proportion of male patients decreased substantially from 2019 to 2021. In addition, there were notable changes in the co-infections of <i>Haemophilus influenzae</i>, parainfluenza virus, and respiratory syncytial virus during the COVID-19 pandemic. The AMR profile of <i>M. catarrhalis</i> also changed significantly, showing increased resistance to ampicillin, but decreased resistance to trimethoprim-sulfamethoxazole and ofloxacin, and a lower proportion of multidrug-resistant isolates. Notably, ampicillin resistance increased among <i>β</i>-lactamase-producing isolates. Before the pandemic, the number and detection rate of isolates, along with resistance to ampicillin and trimethoprim-sulfamethoxazole, were seasonally distributed, peaking in autumn and winter. However, coinciding with local COVID-19 outbreaks, these indices sharply fell in February 2020, and the number of isolates did not recover during the autumn and winter of 2022. These findings indicate that the COVID-19 pandemic has significantly altered the infection landscape of <i>M. catarrhalis</i> in pediatric CAP patients, as evidenced by shifts in the detection rate, demographic characteristics, respiratory co-infections, AMR profiles, and seasonal patterns.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"415-421"},"PeriodicalIF":2.3,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141913303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparison of Mutant Prevention Concentrations of Fluoroquinolones Against ESBL-Positive and ESBL-Negative <i>Klebsiella pneumoniae</i> Isolates from Orthopedic Patients.","authors":"Peng Zou, Zhiquan Chen, Jijun Tu, Xinfeng Chen, Xuejian Liu","doi":"10.1089/mdr.2024.0023","DOIUrl":"10.1089/mdr.2024.0023","url":null,"abstract":"<p><p>The majority of <i>Klebsiella pneumonia</i> isolates possess the extended-spectrum beta-lactamase (ESBL) enzymes. Therefore, <i>K. pneumoniae</i> can easily develop drug resistance. How to effectively overcome the problem of drug resistance in <i>K. pneumoniae</i> is still a research hotspot. This study aimed to compare the mutant prevention concentration (MPC) of ESBL-positive and ESBL-negative <i>K. pneumoniae</i> isolated from orthopedic patients, which may provide a basis for the effective use of drugs to control the enrichment of resistance mutants of <i>K. pneumoniae</i>. The MPC₉₀ values of 55 isolates of ESBL-positive <i>K. pneumoniae</i> against 4 fluoroquinolones were 32 µg/mL for levofloxacin and gatifloxacin, 16 µg/mL for ciprofloxacin, and 4 µg/mL for gemifloxacin. The selection index value was 8 for levofloxacin and ciprofloxacin and 2 for gemifloxacin and gatifloxacin, respectively. For ESBL-negative <i>K. pneumoniae</i> isolates, the MPC₉₀ values were 16 µg/mL for levofloxacin and ciprofloxacin, 4 µg/mL for gemifloxacin, and 32 µg/mL for gatifloxacin. The selection index value was 8 for levofloxacin and ciprofloxacin, 2 for gemifloxacin, and 4 for gatifloxacin. For the ESBL-positive <i>K. pneumoniae</i>, the %T>MIC₉₀ order was gemifloxacin > levofloxacin > ciprofloxacin > gatifloxacin. For the ESBL-negative <i>K. pneumoniae,</i> the %T>MIC₉₀ order was levofloxacin > gemifloxacin > ciprofloxacin > gatifloxacin. The mutant-preventing ability of gatifloxacin and gemifloxacin was the strongest among the 4 fluoroquinolones. So gemifloxacin may be the first choice of drug to treat <i>K. pneumoniae</i> infection.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"391-397"},"PeriodicalIF":2.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141633938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rosalind Franklin Society Proudly Announces the 2023 Award Recipient for Microbial Drug Resistance.","authors":"Dr Anna Carannante","doi":"10.1089/mdr.2024.44723.rfs2023","DOIUrl":"https://doi.org/10.1089/mdr.2024.44723.rfs2023","url":null,"abstract":"","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":"8 1","pages":"353"},"PeriodicalIF":2.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drug Resistance in Biofilm and Planktonic Cells of <i>Achromobacter</i> spp., <i>Burkholderia</i> spp., and <i>Stenotrophomonas maltophilia</i> Clinical Isolates.","authors":"Edeer Iván Montoya-Hinojosa, Licet Villarreal-Treviño, Paola Bocanegra-Ibarias, Adrián Camacho-Ortiz, Samantha Flores-Treviño","doi":"10.1089/mdr.2023.0301","DOIUrl":"10.1089/mdr.2023.0301","url":null,"abstract":"<p><p><b><i>Background:</i></b> Biofilm production in nonfermenting Gram-negative bacteria influences drug resistance. The aim of this work was to evaluate the effect of different antibiotics on biofilm eradication of clinical isolates of <i>Achromobacter</i>, <i>Burkholderia</i>, and <i>Stenotrophomonas maltophilia</i>. <b><i>Methods:</i></b> Clinical isolates were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry in a third-level hospital in Monterrey, Mexico. Crystal violet staining was used to determine biofilm production. Drug susceptibility testing was determined by broth microdilution in planktonic cells and biofilm cells. <b><i>Results:</i></b> Resistance in planktonic cells was moderate to trimethoprim-sulfamethoxazole, and low to chloramphenicol, minocycline, levofloxacin (<i>S. maltophilia</i> and <i>Burkholderia</i>), ceftazidime, and meropenem (<i>Burkholderia</i> and <i>Achromobacter</i>). Biofilm eradication required higher drug concentrations of ceftazidime, chloramphenicol, levofloxacin, and trimethoprim-sulfamethoxazole than planktonic cells (<i>p</i> < 0.05). Levofloxacin showed biofilm eradication activity in <i>S. maltophilia,</i> minocycline and meropenem in <i>Burkholderia</i>, and meropenem in <i>Achromobacter</i>. <b><i>Conclusions:</i></b> Drug resistance increased due to biofilm production for some antibiotics, particularly ceftazidime and trimethoprim-sulfamethoxazole for all three pathogens, chloramphenicol for <i>S. maltophilia</i> and <i>Burkholderia,</i> and levofloxacin for <i>Burkholderia.</i> Some antibiotics could be used for the treatment of biofilm-associated infections in our population, such as levofloxacin for <i>S. maltophilia,</i> minocycline and meropenem for <i>Burkholderia</i>, and meropenem for <i>Achromobacter</i>.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"354-362"},"PeriodicalIF":2.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141727504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bioflavonoid Baicalein Modulates Tetracycline Resistance by Inhibiting Efflux Pump in <i>Staphylococcus aureus</i>.","authors":"Soumitra Moulick, Dijendra Nath Roy","doi":"10.1089/mdr.2024.0099","DOIUrl":"10.1089/mdr.2024.0099","url":null,"abstract":"<p><p>The rise in antibiotic resistance among bacterial pathogens, particularly <i>Staphylococcus aureus</i>, has become a critical global health issue, necessitating the search for novel antimicrobial agents. <i>S. aureus</i> uses various mechanisms to resist antibiotics, including the activation of efflux pumps, biofilm formation, and enzymatic modification of drugs. This study explores the potential of baicalein, a bioflavonoid from <i>Scutellaria baicalensis</i>, in modulating tetracycline resistance in <i>S. aureus</i> by inhibiting efflux pumps. The synergistic action of baicalein and tetracycline was evaluated through various assays. The minimum inhibitory concentration (MIC) of baicalein and tetracycline against <i>S. aureus</i> was 256 and 1.0 μg/mL, respectively. Baicalein at 64 μg/mL reduced the MIC of tetracycline by eightfold, indicating a synergistic effect (fractional inhibitory concentration index: 0.375). Time-kill kinetics demonstrated a 1.0 log CFU/mL reduction in bacterial count after 24 hours with the combination treatment. The ethidium bromide accumulation assay showed that baicalein mediated significant inhibition of efflux pumps, with a dose-dependent increase in fluorescence. In addition, baicalein inhibited DNA synthesis by 73% alone and 92% in combination with tetracycline. It also markedly reduced biofilm formation and the invasiveness of <i>S. aureus</i> into HeLa cells by 52% at 64 μg/mL. These findings suggest that baicalein enhances tetracycline efficacy and could be a promising adjunct therapy to combat multidrug-resistant <i>S. aureus</i> infections.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"363-371"},"PeriodicalIF":2.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141917117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the Expression of Efflux Pumps in <i>Pseudomonas aeruginosa</i> in Exposure to Sodium Dodecyl Sulfate, Didecyldimethylammonium Chloride, and Octenidine Dihydrochloride.","authors":"Khawla Alsamhary","doi":"10.1089/mdr.2024.0070","DOIUrl":"10.1089/mdr.2024.0070","url":null,"abstract":"<p><p>Emerging resistance of Gram-negative bacteria, including <i>Pseudomonas aeruginosa</i>, to commonly used detergents and disinfectant is encountering us with hazard. Inappropriate use of disinfectants has forced bacteria to gain resistance. The ability of bacteria to extrude substrates from the cellular interior to the external environment has enabled them to persist in exposure to toxic compounds, which is due to existence of transport proteins. Efflux pumps, in Gram-negative bacteria, are proteins responsible for exporting molecules outside of the cell, by crossing the two membranes. In this study, 40 <i>P. aeruginosa</i> strains from hospitals, clinics, and burn center laundries and 40 <i>P. aeruginosa</i> strains from urban laundries were collected. This study evaluated the minimum inhibitory concentration (MIC) level of sodium dodecyl sulfate (SDS), didecyldimethylammonium chloride (DDAC), and octenidine dihydrochloride (Od) in <i>P. aeruginosa</i> strains. The real-time PCR was carried out to evaluate the expression of MexAB-OprM, MexCD-OprJ, and MexXY-OprM efflux system. The obtained results indicated a higher MIC level for SDS, DDAC, and Od in medical laundries. The sub-MIC level of DDAC and Od increased the expression level of MexAB-OprM, MexCD-OprJ, and MexXY-OprM in <i>P. aeruginosa</i> strains, suggesting that efflux pumps contribute to disinfectant resistance in <i>P. aeruginosa</i>.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"385-390"},"PeriodicalIF":2.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141855970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Third Kuwaiti Multicenter Survey of Antibiotic Susceptibility of Anaerobic Bacteria: A Comparative Analysis of 20-Year Data.","authors":"Khalifa Al Benwan,Wafaa Jamal,May Shahin","doi":"10.1089/mdr.2024.0036","DOIUrl":"https://doi.org/10.1089/mdr.2024.0036","url":null,"abstract":"Objective: This study aimed to evaluate antibiotic susceptibility and antimicrobial resistance trends among clinically significant anaerobes in Kuwait hospitals from 2013 to 2022, comparing these findings with data from 2002 to 2012. Methods: The study prospectively collected 2,317 anaerobic isolates from various body sites across four Kuwaiti hospitals between January 2013 and December 2022. The minimum inhibitory concentrations for 11 antianaerobic antibiotics were determined using E-test methodology. The study analyzed trends and resistance rates across two periods: 2013-2017 and 2018-2022, using statistical analysis for resistance comparison. Results: Of the 2,317 isolates, most were from wounds (42.2%), fluids (28.0%), and tissues (20.5%). Bacteroides fragilis was the most common pathogen (34.0%), followed by Prevotella bivia (13.4%). Over 90% of isolates were susceptible to imipenem, meropenem, tigecycline, and metronidazole, whereas lower susceptibility was observed for penicillin, amoxicillin-clavulanic acid, and clindamycin. Notable differences in resistance profiles since 2002 were observed, especially in amoxicillin-clavulanic acid, piperacillin, piperacillin-tazobactam, and clindamycin. Conclusion: Owing to detected resistance to all antibiotics, susceptibility testing for anaerobic isolates is recommended in severe infections to ensure effective antimicrobial therapy. Continuous surveillance is crucial for developing antibiotic policies to manage invasive anaerobic infections.","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":"64 1","pages":"372-384"},"PeriodicalIF":2.6,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic Alterations Associated with Colistin Resistance Development in <i>Escherichia coli</i>.","authors":"Fatemeh Alsahlani, Mehri Haeili","doi":"10.1089/mdr.2024.0026","DOIUrl":"10.1089/mdr.2024.0026","url":null,"abstract":"<p><p><b><i>Background:</i></b> The increased incidence of infections due to multidrug-resistant Gram-negative bacteria has led to the renewed interest in the use of 'forgotten' antibiotics such as colistin. In this work, we studied the chromosomal colistin resistance mechanisms among laboratory-induced colistin-resistant <i>Escherichia coli</i> isolates. <b><i>Methods:</i></b> Three colistin-susceptible (ColS) clinical isolates of <i>E. coli</i> assigning to ST131, ST405, and ST361 were exposed to successively increasing concentrations of colistin. The nucleotide sequences of <i>pmrA</i>, <i>pmrB</i>, <i>pmrD</i>, <i>phoP</i>, <i>phoQ</i>, and <i>mgrB</i> genes were determined. The fitness burden associated with colistin resistance acquisition was determined by measuring the <i>in vitro</i> growth rate. <b><i>Results:</i></b> Colistin resistance induction resulted in 16-64 times increase in colistin MICs in mutants (<i>n</i> = 8) compared with parental isolates. Analysis of chromosomal genes in colistin-resistant mutants compared with those of ColS ancestors revealed genetic alterations confined to PmrAB two-component system and included PmrA G53R/R81S/L105P and PmrB E121K/E121A/A159P/A159V/G302E changes. The PmrB E121 was found as a critical position for colistin resistance development being altered in three mutants with different ancestors. The acquired colistin-resistance phenotype was stable following 10 consecutive passages in the absence of selective pressure of colistin and it did not alter the susceptibility of mutants to other antimicrobial agents. All mutants exhibited growth rates similar to their respective ColS ancestors, except for one isolate, which revealed a significant growth defect. <b><i>Conclusion:</i></b> Our results revealed that colistin resistance in <i>E. coli</i> was more related to PmrAB alterations, which did not impose a fitness cost in most cases.</p>","PeriodicalId":18701,"journal":{"name":"Microbial drug resistance","volume":" ","pages":"325-331"},"PeriodicalIF":2.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141437208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}