[Bacteremia caused by Escherichia coli and Klebsiella pneumoniae producing extended-spectrum betalactamases: mortality and readmission-related factors]

Abstract

Background and objective: The incidence of bloodstream-infections caused by extended-spectrum betalactamases (ESBL)-producing bacteria has increased exponentially. The objective of this study is to determine the factors related to mortality and readmission in these patients.

Patients and methods: Socio-epidemiological, clinical and laboratory data has been collected (from January, 1st 2008 to April, 31th 2011). They were classified as nosocomial, healthcare-associated or community-acquired data. A descriptive research was conducted to determine the main differences in terms of responsible bacteria and variables associated with mortality and readmission rates. The following techniques were used to compare variables: Student's t-test, one-way ANOVA test, χ(2)-test and Fisher's exact test. A logistic-regression analysis was performed to identify variables independently related to mortality and readmission, using SPSS(®) statistics software v18.

Results: A total of 68 patients were included in the study: 73.5% of the infections were caused by Escherichia coli (E. coli), and 26.5% by Klebsiella pneumoniae (K. pneumoniae). Nosocomial origin, critical condition of patients, and abdominal location were more frequent when K. pneumoniae was isolated; urinary tract was the most frequent site of E. coli infections. The in-hospital mortality reached 20.6%, and 24% during the follow-up period. The main factor associated to in-hospital mortality was previous antibiotic treatment (OR 8.37; CI 95%: 1.094-64.091); within the follow-up period, the first mortality factor was central venous catheterization (OR 8.416; CI 95%: 1.367-51.821). Readmission was required in 55.5% of patients. The main variables associated were nosocomial origin (OR 4.801; CI 95%: 1.057-21.802) and previous antibiotic treatment (OR 4.715; CI 95%: 1.125-19.766). Inadequate antibiotic treatment was not associated with increased mortality or readmission. Conclusions ESBL-producing E. coli and K. pneumoniae bloodstream-infections are linked to a high mortality and readmission risk. Previous antibiotic treatment is the main factor associated to a poor outcome.

Keywords: Bacteremia; Bacteriemia; Betalactamasas de espectro extendido; Escherichia coli; Extended-spectrum betalactamases; Klebsiella pneumoniae; Mortalidad; Mortality; Readmission; Reingreso.