Comparison between Perianal Swab and Stool Specimens for Detecting Colonization with Extended-Spectrum Beta-Lactamase-Producing and Fluoroquinolone-Resistant Enterobacterales

Stool specimens are frequently used to detect gastrointestinal tract colonization with antimicrobial-resistant enteric bacteria, but they cannot be rapidly collected. Perianal swab specimens can be collected more quickly and efficiently, but data evaluating their suitability as a specimen type for this purpose are sparse. We performed selective culture for extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) and fluoroquinolone-resistant Enterobacterales (FQRE) using paired perianal swab and stool specimens that were collected within 1 day of each other from hematopoietic cell transplant recipients and patients with acute leukemia. Nineteen (7.6%) of 251 stool specimens yielded ESBL-E and 64 (26%) of 246 stool specimens yielded FQRE. The positive percent agreement of perianal swab specimens compared to stool specimens was 95% (18/19; 95% confidence interval [CI], 74% to 100%) for detecting ESBL-E and 95% (61/64; 95% CI, 87% to 99%) for detecting FQRE. The concordance between specimen types was 98% (95% CI, 97% to 100%). Perianal swabs are a reliable specimen type for surveillance of the gastrointestinal tract for ESBL-E and FQRE.