Lack of Change in Susceptibility of Pseudomonas aeruginosa in a Pediatric Hospital Despite Marked Changes in Antibiotic Utilization

INTRODUCTION It is assumed that a direct relationship exists between the extent of use of any given antibiotic or antibiotic class and the degree of susceptibility or resistance on the part of various bacteria to that antibiotic or class. METHODS Pseudomonas aeruginosa susceptibility rates and utilization of key antipseudomonal antibiotics in a pediatric hospital, reflected as grams/1,000 patient days, were studied over a 7-year period. RESULTS While the volume of use of a number of antibiotics changed dramatically over this time period, susceptibility of Pseudomonas to these same agents remained relatively stable. The use of aminoglycosides decreased 14.5% while that of piperacillin/tazobactam increased 92% over the period of observation while susceptibility generally varied by <10%. CONCLUSION Contrary to popular belief, changes in antibiotic utilization patterns do not always result in changes in susceptibility thus emphasizing the importance of continual institutional monitoring of antibiotic use and susceptibility patterns.