Molecular characterization of antimicrobial resistance in clinical isolates during 2014 and 2015: trends in South India.

BACKGROUND

species are an important cause of acute diarrheal disease worldwide. This study describes the prevalence of spp. serotypes and their resistance profile in Vellore, South India from 2014 to 2015.

METHODS

From 2014 to 2015, 338 strains were isolated from stool samples at Christian Medical College, Vellore, India. Identification and serotyping was carried out using standard protocols. Antimicrobial susceptibility testing was done against commonly used antibiotics. Multidrug resistance was detected in 157 isolates. A subset of 73 isolates was randomly characterized further for acquired antimicrobial resistance genes in this study.

RESULTS

The resistance profile of the study isolates varied by species and year. isolates were 100% resistant to all tested antibiotics in 2014, whereas in 2015, resistance was found for AMP-NAL-TAX-SXT-FIX. The resistance phenotypes among isolates for the year 2014 and 2015 were AMP-SXT-NAL-NOR-FIX-TAX and AMP-NAL-SXT-TAX-NOR-FIX respectively. Screening for antimicrobial resistance genes in found , , , , B, S and AmpC genes while were found to have only , and S genes respectively. Antimicrobial resistance genes were predominantly seen in AMP-SXT-NAL and AMP-SXT-NAL-NOR resistance phenotypes.

CONCLUSION

prevalence of 4.8% to 4.6% was documented between the years 2014 to 2015 in this study. We show evidence that resistance to commonly used antibiotics continues to increase among spp. in South India. The presence of S and in the study isolates further indicates the threat of spreading resistance to quinolones and third-generation cephalosporins.