Isolation, Identification, Speciation, and Antibiogram of Enterococcus species by conventional methods and Assessment of the Prevalence of vana genotype among VRE
Authors: Gupta Amit 
Published: September 2022

Enterococci are Gram-positive, ovoid cocci that can be found as diplococci or in short chains. These species are found in the typical microbiota of the intestine, oral cavity, vagina, and other areas. Despite being commensals with moderate virulence, these species have lately emerged as important nosocomial infections with increasing drug resistance particularly to vancomycin. This has resulted in their changing patterns of infection that are resistant to conventional antimicrobial therapy. The main objective of this study was to assess the frequency of the VanA genotype among Vancomycin Resistant Enterococci, as well as the isolation, identification, speciation, and antibiotic sensitivity pattern of Enterococci from various clinical specimens. In this six-month study, 500 different clinical specimens such as urine, blood, and pus were collected aseptically from patients suffering from urinary tract infection (UTI), septicemia, and pyogenic illnesses, and a total of 94 Enterococci strains were identified. These isolates were identified and speciated using traditional tests and biochemical processes. Following culture, the disc diffusion technique was used to determine their antibiotic susceptibility pattern, as suggested for common antibiotics. RCR was also used to evaluate the prevalence of the vanA gene among VRE isolates. 88.29% were E. faecalis, 7.88% were E. faecium, 2.12% were E. durans, 1.06 % was E. casseliflavus, and 1.06 % was E. gallinarum, out of a total of 94 isolates. Urine (70.21 %) yielded the most isolates, followed by blood (17.02 %) and pus (17.02 %). Female patients had a higher isolation rate of 73.40 % (69/94) than male patients, who had a rate of 26.59 % (25/94), and the majority of the Enterococcal isolates were from inpatients (62.77 %) rather than outpatients (37.23 %). 30 % of the isolates were hemolytic, whereas 70% were non-hemolytic. The isolates sensitivity patterns revealed that they were resistant to antibiotics such as ampicillin, ciprofloxacin, and gentamicin. The susceptibility test also included 30g discs of vancomycin. Vancomycin resistance is greatest in E. faecium (28 %) 6/83, followed by E. faecalis (8 %) 2\7. All other isolates were vancomycin-susceptible. Vancomycin-resistant isolates made up 8.51 % of the total. Barely urine isolates were tested for nitrofurantoin resistance, which was found to be only 5%. Linezolid sensitivity was found in all of the Enterococci. According to the PCR test for the vanA gene, among total VRE isolates 5 E. faecalis and 1 E. faecium isolates had vanA genotypes with bands of 473bp. A number of studies have revealed an increment in the infection rate and antimicrobial resistance of Enterococci. Elevated isolation rate of VRE has posed threat to therapeutic strategies as now only few antibiotics are susceptible to such isolates. It is thus imperative to execute measures that could stable the VRE augmentation lest a normal commensal would get the status of SARS-CoV-2