Risk of drug resistance in repeat gram-negative infections among patients with multiple hospitalizations.

PURPOSE: Drug resistance in gram-negative bacterial hospital-acquired infections (GNB HAIs) has become ubiquitous in recent years. Patients who experience multiple hospitalizations are at high risk of developing repeat GNB HAIs. This study aims to evaluate the relationship between repeat GNB HAIs and antibiotic susceptibility patterns.

METHODS: Using electronic medical records from three hospitals, 4053 patients were identified with at least one HAI caused by K. pneumoniae or P. aeruginosa over multiple hospitalizations in a 9-year period. Modified Poisson regression was used to evaluate the risk of drug resistance with increasing number of prior susceptible infections. Drug resistance was defined as resistant to carbapenems for K. pneumoniae and resistant to levofloxacin for P. aeruginosa.

RESULTS: In patients with repeat infections, almost 15% of consecutive infections changed from susceptible to drug-resistant. Patients with K. pneumoniae infections had a 1.14 times increased risk of acquiring a drug-resistant HAI with each prior HAI, after adjusting for potential confounders and antibiotic use prior to infection. Patients with P. aeruginosa infections had a 1.23 times increased risk of a drug-resistant infection with each prior P. aeruginosa HAI.

CONCLUSIONS: Prevention of repeat infections in high healthcare utilizers may be important in reducing drug resistance in this population.