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Background: Three Enterococcus isolates obtained from retail chicken isolates collected in 2010-2011 as part of the Colombian Integrated Program for Antimicrobial Resistance Surveillance (COIPARS) showed reduced susceptibility towards linezolid (MIC 8 mg/L).Objectives: This study aimed at detecting resistance mechanism and characterization of isolates resistant to linezolid.Methods: The strains where in 2011-12 analysed using antimicrobials susceptibility testing and PCR methods and Whole genome sequencing (WGS) was performed and analysed without successful detection of the resistance mechanism. All isolates were found negative for the cfr gene and no 23S rRNA mutations were detected. In 2016 with novel resistance gene optrA being described the WGS data were re-analysed using in silico genomic tools for confirmation of species, detection of virulence and resistance genes, MLST and SNP analyses.Results: Three E. faecalis isolates were found positive for the optrA gene encoding resistance to linezolid and phenicols in the newly performed genomic analyses. Additional screening of 37 Enterococci strains from the same study did not detect any further positives.Typing showed that two of these isolates belong to ST59 while the last belongs to ST489. All isolates carry resistance genes towards macrolide-lincosamide-streptogramin B (MLS), tetracycline and phenicols. In addition, the ST489 isolate also carries genes conforming resistance to aminoglycoside and is resistant to quinolones But no plasmid-mediated gene was detected.Conclusions: To the best of our knowledge this is the first description of optrA gene in E. faecalis isolated from poultry meat in the Americas. |