Phenotypic and Genotypic Virulence Factors and Their Association with Antibiotic Resistance in Clinical Isolates of Enterococcus Species in Bangladesh

Author(s): Tahani Momotaz, Rehana Razzak Khan, Fatima Afroz, Sharmin Chowdhury, Md. Nahidul Islam, Mohammad Tanvir Sarwar, Abu Naser Ibne Sattar

Introduction: The emergence of drug resistant Enterococcus spp is now become an important public health threat as it is one of the leading causes of nosocomial infections. This study aimed to disclose the virulence factors and their encoding genes (asa, gelE, esp, ebpR, hyl gene for biofilm; cylA gene for hemolysis; gelE gene for gelatin hydrolysis) and observe their relations with antimicrobial resistance in Enterococci.

Methods: For this cross-sectional study, a total of 87 Enterococci isolated from different clinical samples (urine, blood, wound swab, pus and bile) were collected. Virulence factors were detected phenotypically by observing hemolysis, gelatin hydrolysis and biofilm formation by tissue culture plate method. For detection of virulence genes, conventional multiplex PCR was adopted for all genes except ebpR gene which was identified by single conventional PCR. Kirby Bauer disc diffusion method was used for antimicrobial susceptibility testing.

Results: Among the isolated Enterococci majority were E. faecalis (75%) followed by E. faecium (23%) and E. raffinosus (2%). About 52.3% of E. faecalis and 35% of E. faecium isolates were biofilm producers. Both in E. faecalis and in E. faecium significant association were found between biofilm formation and asa, ebpR, esp genes (p value<.05). Hemolysis was phenotypically observed in 30.8% isolates of E. faecalis and 20% isolates of E. faecium. A significant association was observed between cylA gene and hemolysin production in E. faecalis. Eighty five percent, 52.9% and 70.6% biofilm producing and 80%, 55% and 80% hemolysin producing isolates of E. faecalis were resistant to ciprofloxacin, ampicillin and gentamicin respectively which was statistically significant (p value <.05).

Conclusion: Antibiotic resistance was higher in biofilm and hemolysin producing isolates of both species. All biofilm producing isolates of E. faecalis and E. faecium were sensitive to vancomycin, linezolid, teicoplanin and fosfomycin.