Phenotypic Characterisation, Virulence Determination and Antimicrobial Resistance Pattern of Enterococcus Species Isolated from Clinical Specimen in a Tertiary Care Hospital in Kolkata

Abstract

Introduction: Enterococci are usually normal human commensal of gastrointestinal tract predominantly. They are considered as an important nosocomial pathogen now a day due to its intrinsic as well as increasing acquired antibiotic resistance resulting in a great threat to modern Medicine. Aim: To determine prevalence of Enterococci isolated from clinical specimens with special reference to its virulence and antibiogram conventionally. Materials and Methods: A cross-sectional observational study was conducted over a period of two years (January 2019 to December 2020) with 326 Enterococci, isolated from various clinical specimens received by Department of Microbiology. Enterococci isolated from stool samples were excluded. They were identified and speciated conventionally as per standard laboratory protocol. Gelatinase, haemolysin and biofilm formation was determined for each isolate. Their antibiogram was also determined by disc diffusion methods over Blood agar followed by Minimum Inhibitory Concentration (MIC) testing (as per Clinical and Laboratory Standards Institute (CLSI) guideline). All statistical analysis was done by Chi-square test using Software Statistical Package for the Social Sciences (SPSS) version 22.0. Results: Among the total 4516 samples collected, growth of Enterococci was noted in 7.22% cases. Out of them, E. faecalis (84.05%) out numbered E. faecium. Urine was the most predominant (55.22%) sample. 73.93% isolates produced biofilm whereas 18.40% produced haemolysin and 19.94% produced gelatinase. Most of the isolates were susceptible to vancomycin (94.79%) and linezolid (98.77%). High level gentamicin resistance was seen in 54.6% cases. Ciprofloxacin was the most resistant antibiotic. Vancomycin Resistance Enterococcus (VRE) was detected in 5.21% cases only, out of which Van A type was detected phenotypically in most cases. Conclusion: The high rate of resistance to high-level gentamicin could fail treatment of gentamicin in combination with penicillin group of antibiotics. In clinical samples, the emergence of VRE strains makes treatment options more challenging.