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Published on: March 19, 2018
Comparison between Perianal Swab and Stool Specimens for Detecting Colonization with Extended-Spectrum
Jeffrey M Kubiak1,2, Michael Hovan3, Emily Davidson3
1Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, New York, USA.
Abstract:
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.
Insights
Perianal swabs offer a rapid and reliable alternative to stool samples for detecting antimicrobial-resistant bacteria in the gut. This study shows high agreement between swab and stool results for ESBL-E and FQRE.
Area of Science:
- Clinical Microbiology
- Infectious Diseases
- Healthcare Epidemiology
Background:
- Stool specimens are standard for detecting gastrointestinal antimicrobial-resistant enteric bacteria but are slow to collect.
- Perianal swabs offer faster collection but their utility for this surveillance is not well-established.
- Hematopoietic cell transplant recipients and acute leukemia patients are at high risk for resistant infections.
Purpose of the Study:
- To evaluate the suitability of perianal swabs versus stool specimens for detecting specific antimicrobial-resistant bacteria.
- To assess the diagnostic accuracy of perianal swabs for extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) and fluoroquinolone-resistant Enterobacterales (FQRE).
Main Methods:
- Paired perianal swab and stool specimens were collected from at-risk patients.
- Selective culture was used to identify ESBL-E and FQRE in both specimen types.
- Positive percent agreement and concordance between specimen types were calculated.
Main Results:
- Stool cultures detected ESBL-E in 7.6% and FQRE in 26% of patients.
- Perianal swabs showed 95% positive percent agreement for both ESBL-E and FQRE compared to stool.
- Overall concordance between perianal swabs and stool specimens was high at 98%.
Conclusions:
- Perianal swabs are a reliable and efficient specimen type for surveillance of gastrointestinal colonization with ESBL-E and FQRE.
- This finding supports the use of perianal swabs to expedite the detection of key antimicrobial-resistant organisms.
