Evaluation of antibiotic resistance and quorum sensing assay of Enterococcus faecalis isolates from the urine samples

Abstract

The Gram-positive Enterococci found in the normal flora of the gastrointestinal tract (GIT) and urinary tract infection (UTI) were characterized by high resistance to antibiotics and large virulence. The aim of our study was to evaluate the diversity of antibiotic-resistant and quorum-sensing assays of Enterococcus faecalis isolated from urine samples of children aged between 11 and 15 with UTI. A total of 155 samples were collected from hospitals and diagnostic centres of the Kalaburagi region. The E. faecalis isolates were screened on bile esculin azide agar media. Antibiotic susceptibility test was performed using different antibiotics as per Clinical and Laboratory Standards Institute guidelines. Minimum inhibitory concentrations (MICs) for gentamycin and vancomycin were determined by the method of broth dilution. Quorum sensing assay of E. faecalis was determined by a bioluminescence-based method. The species-level identification of E. faecalis isolates was determined by 16S rRNA polymerase chain reaction amplification. The incidence of E. faecalis in urine samples was found to be 47.74% (74/155). Antimicrobial susceptibility test (AST) indicates that 27% of isolates were multi-drug resistant, showing increased resistance to gentamycin and vancomycin (54.05%). MIC results show that 23 isolates were resistant to gentamycin with a concentration of 128 μg/ml and 17 isolates were resistant to vancomycin with a concentration of 1024 μg/ml. The quorum sensing assay has shown that the normalized relative light units range from 0.4 to 1.2. According to the 16srRNA gene amplification, out of 10 isolates, seven were identified as Enterococcus faecalis and three isolates were Streptococcus gallolyticus. This study emphasizes the development of increased vancomycin resistance of E. faecalis and indicates the presence of virulence factors through the autoinducer assay. It is been suggested that major precautionary measures should be implemented in the eradication of VRE in UTI infection.