In vitro efficacy of Piperacillin/sulbactam, Piperacillin/tazobactam and Cefoperazone/sulbactam against clinical isolates of Pseudomanas aeruginosa- a comparative study

Abstract

Objective: To determine the in vitro efficacy of Piperacillin/sulbactam, Piperacillin/tazobactam and Cefoperazone/sulbactam against clinical isolates of Pseudomanas aeruginosa. Place and duration of study: The study was carried out in the department of microbiology, Armed Forces institute of Pathology from January 2010 to September 2010. Material and Methods: A total of 287 isolates of Pseudomonas aeruginosa recovered from various clinical specimens were taken under consideration. Routine microbiological methods were used to identify the organism. Susceptibility of the isolates was carried out by modified Kirby-Bauer disc diffusion method against piperacillin 100/sulbactam 30 (SPR130ìg), cefoperazone 75/sulbactam 30 (SCF105ìg) and piperacillin 100/tazobactam 10 (TZP110ìg), according to the guidelines provided by Clinical and Laboratory Standards Institute (CLSI). Results: The highest numbers of Pseudomonas aeruginosa isolates were found in pus swabs, followed by urine and endobronchial washings. 75% of clinical isolates of P. aeruginosa were susceptible to tazobactam/piperacillin, 71% to piperacillin/sulbactam and 70% to cefoperazone/sulbactam. The difference between the susceptibility of these three antimicrobials was statistically not significant (p>0.05). Conclusion: We conclude that there was very little difference in the antimicrobial susceptibility of P. aeruginosa to the three beta-lactam/beta-lactamase inhibitor combination drugs studied. Periodic susceptibility testing should be carried out over a period of two to three years, to detect the current resistance trends. Moreover, a rational strategy on the limited and prudent use of anti-Pseudomonal agents is urgently required.