Infectious Disease
Shigella is the leading cause of bystander pathogen exposure to antibiotics due to diarrhea treatment Stephanie A. Brennhofer* Stephanie A. Brennhofer Timothy L. McMurry James A. Platts-Mills Joseph A. Lewnard Elizabeth T. Rogawski McQuade
Pathogens carried asymptomatically at the time of antibiotic treatment experience selection pressure despite not being the intended target of treatment (i.e., bystander pathogens), which can contribute to antimicrobial resistance. We aimed to quantify the amount of bystander exposures that could be attributed to the treatment of individual diarrheal pathogens to inform the value of pathogen-specific diarrhea interventions. We analyzed 15,697 antibiotic courses from 1,715 children aged 0-2 years across 8 sites in the MAL-ED birth cohort study. Pathogens present in a diarrheal stool sample at a high quantity previously determined to be etiologic were considered the cause of antibiotic courses for diarrhea. Pathogens detected in the most recent stool up to 30 days prior to an antibiotic course were considered bystanders. We calculated incidence rates and proportions of bystander pathogen (enteroaggregative E. coli (EAEC), Campylobacter, enterotoxigenic E. coli (ETEC), atypical enteropathogenic E. coli (aEPEC), typical enteropathogenic E. coli (tEPEC), and Shigella) exposures due to 10 leading causes of diarrhea. The incidence rate of bystander pathogen exposures to antibiotics was the highest due to treatment of Shigella (32.5 bystander exposures to any antibiotic per 100 child-years), of which, 10.0 and 7.1 were exposures to macrolides and fluoroquinolones, respectively (Figure). However, only 4.4% of all antibiotic exposures to bystander pathogens were due to Shigella, given the many causes of antibiotic use in this population. The next leading causes of bystander pathogen exposures were rotavirus (18.4 bystander exposures to any antibiotic per 100 child-years), sapovirus (16.3), adenovirus 40/41 (16.1), and ETEC (14.7). Pathogen-specific interventions for diarrhea such as vaccines could prevent some of this burden of bystander exposures to antibiotics.
