Increased mortality associated with a clonal outbreak of ceftazidime-resistant Klebsiella pneumoniae: a case-control study.

Overview

OBJECTIVES: To determine risk factors for ceftazidime-resistant Klebsiella pneumoniae infection and the effect of ceftazidime-resistant K. pneumoniae infection on mortality during an isolated outbreak. DESIGN: Case-control investigation using clinical and molecular epidemiology and prospective analysis of infection control interventions. SETTING: Surgical intensive care unit of a university-affiliated community hospital. PATIENTS: Fourteen case-patients infected with ceftazidime-resistant K. pneumoniae and 14 control-patients. RESULTS: Ten of 14 case-patients had identical strains by pulsed-field gel electrophoresis. Broad-spectrum antibiotic therapy before admission to the unit was strongly predictive of subsequent ceftazidime-resistant K. pneumoniae infection. In addition, patients with ceftazidime-resistant K. pneumoniae infection experienced increased mortality (odds ratio, 3.77). CONCLUSIONS: Cephalosporin restriction has been shown to decrease the incidence of nosocomial ceftazidime-resistant K. pneumoniae. However, isolated clonal outbreaks may occur due to lapses in infection control practices. Reinstatement of strict handwashing, thorough environmental cleaning, and repeat education led to termination of the outbreak. A distinct correlation between ceftazidime-resistant K. pneumoniae infection and mortality supports the important influence of antibiotic resistance on the outcome of serious bacterial infections.