Enterococcal Urinary Tract Infections – An Evolving Trend with Changing Antimicrobial Resistance Patterns

Introduction: Urinary tract infections (UTI) are the most common infections encountered both in the community as well as in hospitalised patients. Enterococcus, which was once considered auropathogen of lower importance, is assuming importance as pathological agent in health care associated as well as community-acquired UTI for the last two to three decades. The aim of the present study was to evaluate the prevalence of enterococcal UTI to see its evolving trend and to study the changing antimicrobial resistance patterns in these isolates. Methods: Mid-stream urine samples of both inpatients and outpatients were collected over a period of 4 years from January 2011 to December 2014 and were processed by standard microbiological techniques. All the patients who had culture-proven enterococcal UTI were included in the study, whereas as urine samples showing other isolates like Escherichia coli, Klebsiella were excluded from the study. The isolates were further tested for antimicrobial susceptibility by disc diffusion method according to the Clinical Laboratory Standard Institute guidelines. Results: The present study analysed the urine samples showing enterococcal growth in cultures. Of the 332 patients having culture-proven UTI, 32 showed enterococcal infections in the year 2011 (about 10% of the positive samples). In 2012 and 2013, patients with enterococcal UTI were 42 and 56 out of a total of 300 and 351 positive samples, respectively. In the year 2014, enterococcus was isolated from 64 patients out of a total of 337 positive samples (19% of the total positive samples). Thus, there was an increasing trend in enterococcal UTI over the years. The study further showed that the females and the hospitalised patients were more vulnerable to enterococcal UTI. An increase in resistance to the commonly used antibiotics was found. Of the various antimicrobials tested, Enterococci showed the highest increase in resistance to Penicillin, Ampicillin, Amoxicillin clavulanate and Ciprofloxacin and an intermediate increase in resistance to Amikacin and Nitrofurantoin. The isolates showed the lowest increase in resistance to Teicoplanin, Vancomycin and Linezolid. Conclusion: The evolving epidemiology of UTI should be kept in mind while treating UTI, especially those with initial treatment failures. Antibiotic drug resistance has become a major threat because of misuse of drugs. This demands antimicrobial stewardship in hospitals and also institution of guidelines for empiric therapy where cultures are not available. This will help in better patient care, management and limit the spread of resistant strains.