Antibiogram and genetic relatedness of clinical isolates of Enterococcus spp. in Mangalore, India.

Introduction: Drug-resistant Enterococcus species is a persisting clinical problem and may serve as a reservoir of resistant genes. The present study was undertaken in Mangalore, India to know the antibiogram and genetic relatedness of Enterococcus spp. isolated from clinical samples.

Methodology: A total of 150 non-repetitive Enterococcus spp. isolated from clinical samples were subjected to antimicrobial susceptibility testing by Kirby Bauer disk diffusion method. Molecular typing of the isolates was done by Random amplification of polymorphic DNA (RAPD).

Results: Among the 150 isolates, 79 were from urine, 68 from pus and three from blood samples. Of this 58.7 % were E. faecalis and the remaining were E. faecium. Urinary isolates of E. faecium showed a higher percentage of antibiotic resistance when compared to E. faecium isolates from pus (p < 0.001). E. faecium from blood samples were resistant to ampicillin, penicillin, ciprofloxacin and were sensitive to vancomycin and teicoplanin. E. faecalis blood isolates were resistant to ciprofloxacin, penicillin, and erythromycin. 73% of Enterococcus isolates from pus were resistant to erythromycin. All the Enterococcus spp. were sensitive to vancomycin. Among the total Enterococcus isolates 44 were high-level aminoglycoside resistant (HLAR) by disc diffusion method which corresponded to MIC of > 500 µg/mL for gentamicin and > 1000 µg/mL for streptomycin. These isolates were subjected to RAPD, which showed similarity and differences in the banding patterns.

Conclusions: Our study showed a baseline resistance among Enterococcus spp. in our area, which poses a challenge to the treating physicians and a reservoir for transmission of antibiotic resistant genes.