Isolation of vanA-Mediated Vancomycin-Resistant Enterococcus faecalis (ST1912/CC116) and Enterococcus faecium (ST80/CC17), optrA-Positive Linezolid-Resistant E. faecalis (ST32, ST1902) from Human Clinical Specimens in Bangladesh

Abstract

Background/Objectives: Enterococcus is one of the major nosocomial pathogens. The present status of antimicrobial resistance determinants and virulence factors was analyzed for current Enterococcus causing infectious diseases in Bangladesh. Methods: Clinical isolates of Enterococcus recovered from various specimens in a tertiary care hospital were analyzed. Antimicrobial susceptibility was measured by a broth microdilution test, and resistance genes/virulence factors were detected by uniplex/multiplex PCR, along with sequencing analysis as required. The sequence type (ST) of E. faecalis and E. faecium was identified based on a multilocus sequence typing (MLST) scheme. Results: For a one-year period, a total of 143 isolates (135 E. faecalis, 7 E. faecium, and 1 E. hirae) were collected. Although all E. faecalis isolates were susceptible to penicillin, high resistance rates were noted against erythromycin (87%) and levofloxacin (62%). High-level resistance to gentamicin was detected in 30% of E. faecalis and 86% of E. faecium. Vancomycin resistance due to vanA was identified in one isolate each of E. faecalis (ST1912, CC116) and E. faecium (ST80, CC17). Three E. faecalis isolates (2.2%) with ST32 or ST1902 were resistant to linezolid, harboring optrA-fexA. Conclusions: The present study identifies the vancomycin-resistant Enterococcus harboring vanA from humans in Bangladesh and shows the potential spread of optrA in multiple lineages of E. faecalis.