Culture of Rectal Swab Specimens for Enteric Bacterial Pathogens Decreases Time to Test Result While Preserving Assay Sensitivity Compared to Bulk Fecal Specimens

Abstract

Diarrheal illness is a major cause of morbidity and mortality throughout the world, yet the etiologic agent of many cases of gastrointestinal illness remains unspecified, often due to the lack of convenient, timely, and sensitive diagnostic testing. Although bulk fecal specimens remain the recommended specimen type for enteric culture, rectal swabs may be an option preferred by clinicians and patients due to the convenience and timing of collection. However, the lack of data evaluating the sensitivity of rectal swabs compared to fecal specimens for detection of enteric pathogens precludes this specimen type from being recommended by national guidelines. In this study, we retrospectively reviewed 480 paired rectal swab and fecal specimens submitted for enteric culture to the Barnes-Jewish Hospital and St. Louis Children’s Hospital microbiology laboratories in St. Louis, MO, from 2002 to 2017. We report 32% positivity of paired specimens with an overall agreement of 93% and Cohen's κ of 0.84 (95% confidence interval, 0.78 to 0.89). Additionally, we evaluated the time to result from the time of patient presentation to the health care setting and demonstrate that rectal swabs have a significantly shorter time to an actionable result than bulk fecal specimens (median, 67.4 h versus 78.4 h, respectively; P < 0.001). These findings indicate that rectal swabs facilitate on-demand culture-based testing with a sensitivity comparable to that of fecal specimens and thus should be recommended for enteric bacterial culture when bulk fecal specimens are unavailable.

Setting up a Hospital Based Diarrhoea Surveillance System in a Low- and Middle-Income Country: Lessons Learned

“…Regrettably, diarrhea stool collection or handling process-as central to etiologic-pathogen isolation, are often not exhaustively discussed. Delays in reporting laboratory results can have a significant impact on patient diagnosis and treatment decisions (15) (16) as factors related to microbe stability, such as time and temperature, are major contributors to false results (17) especially for fastidious organisms such as Shigella . For example, Shigella-positive stool samples stored at room temperature for more than 45 minutes, may be culture negative unless stored at 4 degrees or less (18).…”

“…There is paucity of data that specifically addresses delays in the context of clinical specimen collection and handling prior to lab transportation, other samples other than HIV, COVID 19 or blood samples (18) (19) (14). Stool sample collections or diarrhoea samples are rarely discussed in the context of individual delays in the sample collection from patient to lab processing cascade (16). Delayed sample collection and processing can have significant implications for antimicrobial resistance (AMR) in low- and middle-income countries (LMICs).…”

Diagnostic testing practices for diarrhoeal cases in South African public hospitals

“…Rectal swabs or wipes should be investigated to address compliance. Swabs are more convenient for both patients and clinicians and demonstrate decreased time to results [ 12 ]. Wipes are efficient in the detection of both bacterial and viral pathogens [ 13 , 14 ], and collection without requiring nursing assistance, may address compliance issues.…”

Bacterial Carriage of Genes Encoding Fibronectin-Binding Proteins Is Associated with Long-Term Persistence of Staphylococcus aureus in the Nasal and Gut Microbiota of Infants

“…Thereafter, gut colonization was assessed by quantitative culturing of feces. The latter method could be considered more sensitive, although in the case of enteric pathogens the culturing of rectal swabs is as sensitive as the culturing of feces ( 32 ). There is no reason to believe that this is not also true for S. aureus .…”