The influence of beta-lactam prescribing patterns on resistance rates among various adult ICU populations

Sara Parli, University of Kentucky College of Pharmacy; Wilbur Rutter, University of Kentucky College of Pharmacy; Daniel Davenport, University of Kentucky College of Medicine; Phillip Chang, University of Kentucky College of Medicine

Current knowledge exists that overuse of antibiotics leads to increased bacterial resistance to drug therapy. Gram negative bacterial resistance is increasing in prevalence, with clinicians at heightened concern, especially in the intensive care unit (ICU). Meropenem has been described in the management of intra abdominal infection, specifically in moderate to severe infection. Meropenem has also been reported to induce chromosomal beta-lactamases, specifically in vitro. Limited data is published regarding this resistance pattern and meropenem usage in the adult ICU patient population.

Increased use of meropenem leads to increased resistance of other beta-lactams to gram negative bacteria.

We collected drug consumption data of meropenem use across three ICU populations including trauma/surgical, cardiovascular, and medicine ICUs in 2013. Antibiotic usage was classified using the World Health Organization definition of defined daily dose (DDD). These DDD were further categorized by ICU per 1000 patient days. The susceptibility rates of piperacillin/tazobactam to Pseudomonas aeruginosa was also collected for each unit.

The total DDD by ICU per 1000 patients was 21.97, 101.62, and 157.35 for trauma/surgical, cardiovascular, and medicine ICUs respectively, in 2013. Susceptibility rates of piperacillin/tazobactam to Pseudomonas aeruginosa were 94%, 67%, and 64% for trauma/surgical, cardiovascular, and medicine ICUs respectively. Pearson Correlation coefficient was calculated, r = -0.97, p = 0.157.

Meropenem usage is inversely correlated to piperacillin/tazobactam susceptibility to Pseudomonas aeruginosa. Further analysis should be done to investigate other correlations of increased antibiotic use to gram negative bacterial resistance. When possible, meropenem should be reserved for known or suspected multi-drug resistance bacterial infection.