Antimicrobial-Resistant Bacteremia in the Elderly: Risk of Previous Hospitalization

SummaryBackgroundStudies have shown a positive correlation between hospital admission and antimicrobial-resistant bacteria (ARB)-related community-acquired bacteremia (CAB), however, the definition regarding the duration from prior hospitalization as having risks for such infections varies between literatures. Therefore, we conducted a retrospective analysis to determine the time-effect of recent hospitalization on the risk of CAB due to extended-spectrum beta-lactamases (ESBLs)-producing Enterobacteriaceae in elderly patients.MethodsFrom 2006 to 2008, all consecutive episodes of documented bacteremia developed within first 48 h of hospital admission due to E. coli and K. pneumoniae in patient age of 65 or greater were retrospectively enrolled.ResultsOut of 494 non-duplicated CAB episodes, 9.5% were due to ESBLs-producing E. coli/K. pneumoniae. Age, history of previous hospital admission, and nursing home residents were independently associated with the risk for CAB due to ESBLs-producing E. coli/K. pneumoniae. History of previous hospitalization was the most significant one among these risks and the effect was time-dependent: within 2∼30 days (OR 8.8; 95% CI 1.9 to 41.2), 31∼90 days (OR 9.0; 95% CI 1.9 to 41.2), 91∼180 days (OR 5.6; 95% CI 1.1 to 29.1), 181∼360 days (OR 5.5; 95% CI 1.0 to 29.1) and over 360 days (OR 3.5; 95% CI 0.5 to 22.7).ConclusionOur study showed that the risk of CAB in elderly due to ESBLs-producing E. coli/K. pneumoniae was highly associated with history of recent hospital admissions, and the effect can be prolonged up to 360 days after discharge.