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Genetic characterization of fluoroquinolone-resistant Escherichia coli associated with bovine mastitis in India.

ABSTRACT: AIM:The present study was undertaken to characterize the mutation in gyrA (DNA gyrase) and parC (topoisomerase IV) genes responsible for fluoroquinolone resistance in Escherichia coli isolates associated with the bovine mastitis. MATERIALS AND METHODS:A total of 92 milk samples from bovine mastitis cases were sampled in and around Puducherry (Southern India). Among these samples, 30 isolates were bacteriologically characterized as E. coli. Minimum inhibitory concentrations (MIC) of fluoroquinolones of these 30 E. coli isolates were evaluated by resazurin microtiter assay. Then, the quinolone resistance determining region (QRDR) (gyrA and parC genes) of these E. coli isolates was genetically analyzed for determining the chromosomal mutation causing fluoroquinolone resistance. RESULTS:E. coli isolates showed a resistance rate of 63.33%, 23.33% and 30.03% to nalidixic acid, ciprofloxacin and enrofloxacin, respectively. Mutations were found at 83(rd) and 87(th) amino acid position of gyrA gene, and at 80(th) and 108(th) amino acid position of parC gene in our study isolates. Among these five isolates, one had a single mutation at 83 amino acid position of gyrA with reduced susceptibility (0.5 µg/ml) to ciprofloxacin. Then, in remaining four isolates, three isolates showed triple mutation (at gyrA: S83?L and D87?N; at parC: S80?I) and the fifth isolate showed an additional mutation at codon 108 of parC (A108?T) with the increased ciprofloxacin MIC of 16-128 µg/ml. The most common mutation noticed were at S83?L and D87?N of gyrA and S80?I of ParC. CONCLUSION:The study confirms the presence of mutation/s responsible for fluoroquinolone resistance in QRDR of gyrA and parC genes of E. coli isolates of animal origin, and there is increased rate of fluoroquinolone resistance with high-level of MIC. The mutations observed in this study were similar to that of human isolates.

SUBMITTER: Balakrishnan S

PROVIDER: S-EPMC4983120 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Genetic characterization of fluoroquinolone-resistant Escherichia coli associated with bovine mastitis in India.

Balakrishnan Sangeetha S Antony Prabhakar Xavier PX Mukhopadhyay Hirak Kumar HK Pillai Raghavan Madhusoodanan RM Thanislass Jacob J Padmanaban Vijayalakshmi V Srinivas Mouttou Vivek MV

Veterinary world 20160711 7

<h4>Aim</h4>The present study was undertaken to characterize the mutation in gyrA (DNA gyrase) and parC (topoisomerase IV) genes responsible for fluoroquinolone resistance in Escherichia coli isolates associated with the bovine mastitis.<h4>Materials and methods</h4>A total of 92 milk samples from bovine mastitis cases were sampled in and around Puducherry (Southern India). Among these samples, 30 isolates were bacteriologically characterized as E. coli. Minimum inhibitory concentrations (MIC) o ...[more]

PMID: 27536030

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Project description:BackgroundEscherichia coli bovine mastitis is a disease of significant economic importance in the dairy industry. Molecular characterization of mastitis-associated E. coli (MAEC) did not result in the identification of common traits. Nevertheless, a mammary pathogenic E. coli (MPEC) pathotype has been proposed suggesting virulence traits that differentiate MAEC from commensal E. coli. The present study was designed to investigate the MPEC pathotype hypothesis by comparing the genomes of MAEC and commensal bovine E. coli.ResultsWe sequenced the genomes of eight E. coli isolated from bovine mastitis cases and six fecal commensal isolates from udder-healthy cows. We analyzed the phylogenetic history of bovine E. coli genomes by supplementing this strain panel with eleven bovine-associated E. coli from public databases. The majority of the isolates originate from phylogroups A and B1, but neither MAEC nor commensal strains could be unambiguously distinguished by phylogenetic lineage. The gene content of both MAEC and commensal strains is highly diverse and dominated by their phylogenetic background. Although individual strains carry some typical E. coli virulence-associated genes, no traits important for pathogenicity could be specifically attributed to MAEC. Instead, both commensal strains and MAEC have very few gene families enriched in either pathotype. Only the aerobactin siderophore gene cluster was enriched in commensal E. coli within our strain panel.ConclusionsThis is the first characterization of a phylogenetically diverse strain panel including several MAEC and commensal isolates. With our comparative genomics approach we could not confirm previous studies that argue for a positive selection of specific traits enabling MAEC to elicit bovine mastitis. Instead, MAEC are facultative and opportunistic pathogens recruited from the highly diverse bovine gastrointestinal microbiota. Virulence-associated genes implicated in mastitis are a by-product of commensalism with the primary function to enhance fitness in the bovine gastrointestinal tract. Therefore, we put the definition of the MPEC pathotype into question and suggest to designate corresponding isolates as MAEC.

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Genetic characterization of fluoroquinolone-resistant Escherichia coli associated with bovine mastitis in India.

Publications

Genetic characterization of fluoroquinolone-resistant Escherichia coli associated with bovine mastitis in India.

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