High Burden of Extended-Spectrum β-Lactamase–Producing Escherichia coli and Klebsiella pneumoniae Bacteremia in Older Adults: A Seven-Year Study in Two Rural Thai Provinces

Escherichia coli and Klebsiella pneumoniae are two of the most common causes of bloodstream infections (BSIs) worldwide.1,2 β-Lactam antibiotics are the preferred treatment because of their selective toxicity, broad spectrum of activity, and low cost.3,4 However, E. coli and K. pneumoniae, and other Enterobacteriaceae, have developed extended-spectrum β-lactamase (ESBL)–producing capability and can hydrolyze penicillins, cephalosporins, and monobactams, rendering them clinically ineffective.5 Extended-spectrum β-lactamase–producing E. coli and K. pneumoniae are increasingly reported worldwide in hospital and community settings, resulting in prolonged and more expensive hospitalizations and increased morbidity and mortality.6,7 Prompt identification is essential for appropriate treatment and improved patient outcomes.8,9 Extended-spectrum β-lactamase–producing E. coli have been identified throughout Thailand,10–13 with the first documented case in 1994,14 and a prevalence among different clinical specimens ranging from 22% to 59%, and evidence that they are becoming more common.10–13,15 However, representative estimates of the incidence of ESBL-producing E. coli and K. pneumoniae and longitudinal trends in antimicrobial resistance are currently limited in Southeast Asia. This study aimed to expand our understanding of ESBL-producing pathogen disease burden by estimating trends in population-based E. coli and K. pneumoniae bacteremia incidence, changes over time in the proportion of these cases due to ESBL-producing organisms, susceptibility profiles to other antibiotics, and the probability of recurrent infections. This study used the same well-established surveillance database that was previously used to estimate the incidence and susceptibility profiles of several other pathogens in rural Thailand.16–19