Case-case-control study of patients with carbapenem-resistant and third-generation-cephalosporin-resistant Klebsiella pneumoniae bloodstream infections

Abstract

Strains of third-generation-cephalosporin-resistant Klebsiella pneumoniae (3GCRKP) and carbapenem-resistant K. pneumoniae (CRKP) are rapidly spreading. Evidence is needed to establish whether differences exist between patients at risk for 3GCRKP and those at risk for CRKP bloodstream infections (BSIs); thus, this retrospective case-case-control study was conducted to determine if the risk factors for these two infections differ. The inclusion criteria for cases were positive blood cultures for K. pneumoniae, first episode of BSI, age of 18 years, and susceptibility results indicating resistance to either third-generation cephalosporins (3GCRKP group) or carbapenems and cephalosporins (CRKP group). Controls were patients admitted for 72 h and were matched to cases by month/year and medical unit. Variables of interest were analyzed by univariate analysis, and those of significance were analyzed by logistic regression. In total, 111 patients with 3GCRKP BSIs and 43 patients with CRKP BSIs were matched to 154 controls. Multivariate analyses of 3GCRKP case and control groups demonstrated that a length of stay (LOS) of >40 days (odds ratio [OR], 17.7; 95% confidence interval [CI], 3.7 to 84.3), the use of antibiotics in the past 90 days (OR, 4.3; 95% CI, 1.5 to 11.9), and the presence of a central venous catheter (OR, 4.1; 95% CI, 1.3 to 13.4) were independent risk factors. Multivariate analyses of the CRKP case and control groups demonstrated that a LOS of >40 days (OR, 13.5; 95% Cl, 2.9 to 62.8) and the use of antibiotics in the past 90 days (OR, 5.9; 95% CI, 1.3 to 26.5) were independent risk factors. Similar factors put patients at risk for these two types of K. pneumoniae BSIs.Copyright