Enterococci: A journey of a successful pathogen

Introduction: A dynamic homeostasis is maintained between the host and native bacteria of the gastrointestinal tract in humans, but migration of bacteria from the gut to other organs can lead to disease or death. Enterococci, traditionally viewed as commensal bacteria are now acknowledged to be organisms capable of causing life-threatening infections in humans, especially in the nosocomial environment. The existence of Enterococci in such a dual role is facilitated by its intrinsic and acquired resistance to virtually all antibiotics currently in use. Objective: The present pilot study was taken up to compare the multidrug resistance prevalence in commensal Enterococci and pathogenic Enterococci. Material and methods: A total of 50 commensal Enterococci isolated from stool samples and 50 clinical samples yielding Enterococci were taken for the study. Antibiotic susceptibility testing was done using Kirby Bauer’s disk diffusion method. Minimum inhibitory concentration of Vancomycin was tested by using E- strip. Results: Among 50 commensal Enterococci, majority showed resistance to Ampicillin 50 (100%), Erythromycin 38 (76%), Clindamycin 30 (60%), higher level of resistance to high level Gentamycin 14 (28%), Linezolid 6 (12%), vancomycin 3 (6%). 23 (46%) isolates showed multi drug resistance (resistance to ? 3 categories of antibiotics). Among 50 clinical isolates, majority showed resistance to Ampicillin 50 (100%), Clindamycin 46 (92%), Tetracycline 46 (92%), Erythromycin 41 (82%), Linezolid resistance was seen in 8 (16%) and Vancomycin resistance in 5 (10%) clinical isolates. 48 (96%) showed multi drug resistance. Conclusion: Boundary line between pathogenic and commensal Enterococci is blurred due to exchange of resistant traits. Regular screening of enterococcal isolates for resistance detection should be implemented. It is very important to consider infection control measures, screening of health care workers, surveillance cultures which can control spread of multidrug resistant Enterococci.