ArticleAntimicrobial agents and chemotherapy2003
Role of AcrR and ramA in fluoroquinolone resistance in clinical Klebsiella pneumoniae isolates from Singapore.
Article in Antimicrobial agents and chemotherapy, 2003. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 79 papers.
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Who cites it
79 citing papers in PubMed, 161 citations in OpenAlex.
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- Clonal dissemination and persistence of Carbapenem-resistantJAC-antimicrobial resistance · 2025Article
- Antibiotic-induced stress responses in Gram-negative bacteria and their role in antibiotic resistance.The Journal of antimicrobial chemotherapy · 2025Review
- Comprehensive Genomic Analysis ofMicroorganisms · 2025Article
- Phenotypic and genomic changes in entericmSphere · 2024Article
- The complex development of psoralen-interstrand crosslink resistance inbioRxiv : the preprint server for biology · 2024Article
- Could traces of fluoroquinolones in food induce ciprofloxacin resistance inMicrobiology spectrum · 2024Article
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- sRNA expression profile of KPC-2-producing carbapenem-resistant Klebsiella pneumoniae: Functional role of sRNA51.PLoS pathogens · 2024Article
- Antibiotic influx and efflux in Pseudomonas aeruginosa: Regulation and therapeutic implications.Microbial biotechnology · 2024Review
- Pyridylpiperazine efflux pump inhibitor boosts in vivo antibiotic efficacy against K. pneumoniae.EMBO molecular medicine · 2024Article
- Antimicrobial resistance patterns ofVeterinary world · 2023Article
- Evaluation of Potential Factors Influencing the Dissemination of Multidrug-ResistantTropical medicine and infectious disease · 2023Review
- Virulence Characteristics and Molecular Typing of Carbapenem-Resistant ST15Antibiotics (Basel, Switzerland) · 2023Article
- Contribution of the efflux pump AcrAB-TolC to the tolerance of chlorhexidine and other biocides inJournal of medical microbiology · 2022Article
- Antimicrobial Susceptibility, Virulence, and Genomic Features of a Hypervirulent Serotype K2, ST65Antibiotics (Basel, Switzerland) · 2022Article
19 more citing papers are in PubMed but not listed here.
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Authors and funding
3 authors at 2 institutions in 2 countries.
Funding
Abstract
The MICs of ciprofloxacin for 33 clinical isolates of K. pneumoniae resistant to extended-spectrum cephalosporins from three hospitals in Singapore ranged from 0.25 to >128 microg/ml. Nineteen of the isolates were fluoroquinolone resistant according to the NCCLS guidelines. Strains for which the ciprofloxacin MIC was >or=0.5 microg/ml harbored a mutation in DNA gyrase A (Ser83-->Tyr, Leu, or IIe), and some had a secondary Asp87-->Asn mutation. Isolates for which the MIC was 16 microg/ml possessed an additional alteration in ParC (Ser80-->IIe, Trp, or Arg). Tolerance of the organic solvent cyclohexane was observed in 10 of the 19 fluoroquinolone-resistant strains; 3 of these were also pentane tolerant. Five of the 10 organic solvent-tolerant isolates overexpressed AcrA and also showed deletions within the acrR gene. Complementation of the mutated acrR gene with the wild-type gene decreased AcrA levels and produced a two- to fourfold reduction in the fluoroquinolone MICs. None of the organic solvent-tolerant clinical isolates overexpressed another efflux-related gene, acrE. While marA and soxS were not overexpressed, another marA homologue, ramA, was overexpressed in 3 of 10 organic solvent-tolerant isolates. These findings indicate that multiple target and nontarget gene changes contribute to fluoroquinolone resistance in K. pneumoniae. Besides AcrR mutations, ramA overexpression (but not marA or soxS overexpression) was related to increased AcrAB efflux pump expression in this collection of isolates.
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