Time trends in the epidemiology of microbial infections at a tertiary care center in west India over last 5 years.

Introduction: Microbiological surveillance data is of crucial importance in appropriate management of patients with infectious diseases. The current study was conducted to study the microbiological surveillance data along with antibiotic sensitivity patterns for isolates collected at a single tertiary care center from Western India over last four years and to analyze the change in the patterns of nosocomial infections seen over the last four year period.

Design: Retrospective study. Culture reports data were retrospectively collected from microbiology department of Sterling hospital Ahmedabad. Isolates from clinical specimen from blood cultures, surgical site swabs, abdominal drain fluid, urine samples and bronchoscopy samples were analysed in present study. Isolates from respiratory secretions includind endotracheal, tracheostomy and sputums were excluded from analysis, Frequency of different organisms which were isolated as well the sensitivity patterns to major antibiotics were recorded.

Results: Among the blood isolates there was a clear trend regarding the emergence of gram positive organisms with Staphylococcus being the most common isolate from 149 blood culture specimens in the period 2008-09 (27.4%). Majority (> 85%) of gram negative isolates causing blood stream infections were sensitive to Amikacin, Cefoperazone-Sulbactam, Piperaciln-Tazobactam, Meropenem and Colistin. On the other hand, sensitivity of gram negative isolates from other sites to these antibiotics was much more variable. Incidence of candidemia went down from 20.3% to 13.4% in 2005-6 and in 2008-09 respectively.

Conclusion: Staphylococcus aureus has emerged as the dominant pathogen causing the blood stream infections in last two years. Piperacilin-tazobactum, cefaperazone-sulbactum or meropenem may be appropriate as empiric antibiotic choice for gram negative blood stream infections along with Amikacin for patients with serious infections.