Community-onset Escherichia coli and Klebsiella pneumoniae bacteremia: influence of health care exposure on antimicrobial susceptibility.

Three hundred forty-one case patients with Escherichia coli bacteremia and 173 case patients with Klebsiella pneumoniae bacteremia were enrolled in this prospective observational study to compare the clinical manifestations of infections in the 2 organisms and to delineate the change in resistance of isolates after health care exposure. Liver abscess, primary bacteremia, and respiratory tract infection were more commonly seen in patients with K. pneumoniae bacteremia, whereas urinary tract infection was more common in those with E. coli bacteremia. The influence of prior hospitalization on resistance of E. coli to some antibiotics could be observed for as long as 6 months after discharge. Patients undergoing procedures in the outpatient setting and nursing home residents also had infections with more resistant E. coli strains than those without hospital exposure within the previous year. However, no difference in resistance was observed in K. pneumoniae isolates from patients in different clinical settings.