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Re‐emergence of chloramphenicol resistance and associated genetic background in Vibrio cholerae O1
Author(s) -
Kumar Pramod,
Yadav Priti,
Nema Akansha,
Goel Ajay K,
Yadava Pramod K
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.907.3
Subject(s) - vibrio cholerae , flor , biology , chloramphenicol , genetics , el tor , gene , cholera , antibiotic resistance , microbiology and biotechnology , antibiotics , bacteria , botany
Acquisition of antibiotic resistance in Vibrio cholerae is a growing concern for management of the disease. Here, we aimed to explore re‐emergence of evolution of chloramphenicol resistance in clinical strains of V. cholerae . A total of 120 strains originating from clinical sources (2004 to 2016) in different parts of India were subjected for antimicrobial susceptibility testing using disc diffusion and broth microdilution with reference to chloramphenicol. Further, the strains were screened using PCR for the presence of chloramphenicol resistance gene floR and the catB9 gene cassette. The floR and catB9 genes were further located in chromosomes followed by DNA sequence and prediction of promoters, higher order structures in mRNA and proteins. All clinical strains carried catB9 gene cassettes associated with super integrons (SI) on chromosome‐II. The floR gene was detected in 90% of the clinical strains and located on Variable Region‐III of Integrated and Conjugative Elements (ICE) on chromosome‐I. A strong positive correlation of floR gene and catB9 with higher chloramphenicol MICs were observed as compared to isolates harbouring catB9 alone. It was observed that floR gene is only responsible for significant increase in MICs but the strains were grouped as reduced susceptible as per CLSI breakpoints. catB9 gene cassette located downstream to a distal promoter (Pc) in SI was associated with very low‐level of resistance to the chloramphenicol. We have observed change in gene localization, change in 5′‐UTR (a ribo‐regulation) and point mutations in coding regions of floR associated with of differential resistance pattern. Acquisition of catB9 (permanently integrated) and floR genes are sequential events and their differential expression is tightly controlled in two different chromosomes. The Screening of floR gene can serve as the basis of V. cholerae classification as resistant