Infection dynamics of vancomycin and inducible clindamycin resistant Enterococcus faecalis in an Indian teaching hospital

ObjectiveTo do surveillance for vancomycin and inducible clindamycin resistance of Enterococcus faecalis (E. faecalis), a Gram-positive bacterium in a teaching hospital.MethodsE. faecalis strains isolated from clinical samples were screened for vancomycin and inducible clindamycin resistance, i.e., D-test positivity, using vancomycin screen agar and blood agar plates, respectively. For the D-test screening, erythromycin resistant (Er-r) and clindamycin sensitive (Cd-s) strain were used.ResultsOf 265 isolated E. faecalis strains, 159 (60%) were vancomycin resistant Enterococcus (VRE) and 106 were vancomycin sensitive Enterococcus (VSE). Of 265 strains, 42 were constitutively resistant to clindamycin and erythromycin and of 148 Er-r and Cd-s strains, 87 (32.83%) had D-test positivity, while the rest 61 strains were D-test negatives. D-test results examined with 6 hospital factors as bivalents, only 2 factors, the VSE/VRE and the presence/absence of prior antibiotic use > 90 days bivalent were statistically significant. A VRE strain with D-test positivity would be picked up 0.570 2 times more frequently than a strain with VSE and D-test positivity. Also, patients with prior antibiotic use > 90 days had 3.737 5 times more chance of picking up D-test positive strains than patients without any prior antibiotic use. Resistance pattern of E. faecalis strains to individual 14 antibiotics were recorded; the maximum values of resistance were against ampicillin 10 μg/disc and linezolid 30 μg/disc. Student's t-test for hospital acquired and community acquired data revealed that drug resistant strains were equally prevalent in both sources.ConclusionsPrevalence of 60% VRE in both hospital and adjoining community creates consternation. In total 87 (32.83%) strains had D-test positivity; patients who had used antibiotics within the last 90 days have got an ample chance of picking of D-test positive E. faecalis. D-test protocol should be followed with clinical samples in hospitals for Gram-positive bacteria.