Laboratory identification of anaerobic bacteria isolated on Clostridium difficile selective medium

Abstract

Despite increasing interest in the bacterium, the methodology for Clostridium difficile recovery has not yet been standardized. Cycloserine-cefoxitin fructose taurocholate (CCFT) has historically been the most used medium for C. difficile isolation from human, animal, environmental, and food samples, and presumptive identification is usually based on colony morphologies. However, CCFT is not totally selective. This study describes the recovery of 24 bacteria species belonging to 10 different genera other than C. difficile, present in the environment and foods of a retirement establishment that were not inhibited in the C. difficile selective medium. These findings provide insight for further environmental and food studies as well as for the isolation of C. difficile on supplemented CCFT.

C. difficilemay be overdiagnosed in adults and is a prevalent commensal in infants

“…Diarrheal symptoms, often the initial diagnostic prompt, are not specific to CDI [48][49][50][51] and pseudomembranous colitis, long thought to be characteristic (and often eponymously referred to as "C. difficile colitis"), may indeed be caused by other enteropathogens, such as C. innocuum or E. coli 8,9,52 . Additional challenges include the large variability in sensitivity and specificity in diagnostic laboratory tests 40,[53][54][55][56][57][58][59][60][61][62] , contradicting results between cultivation and toxin detection assays 63 and an excessive reliance on single molecular tests 64 . Recommended guidelines discourage stand-alone tests for CDI diagnosis and recommend a two-step procedure 53,57 , but due to costs, test availability, capacity and turnaround times, diagnostic algorithms vary between hospitals and often deviate from recommended procedures 58 .…”

“…Diarrheal symptoms, often the initial diagnostic prompt, are not specific to CDI(Bartlett & Gerding, 2008; Jackson et al, 2016; Polage et al, 2012; Reich et al, 2019) and pseudomembranous colitis, long thought to be characteristic (and often eponymously referred to as “ C. difficile colitis”), may indeed be caused by other enteropathogens, such as C. innocuum or E. coli(Chia et al ., 2018; Tang et al ., 2014, 2016) . Additional challenges include the large variability in sensitivity and specificity in diagnostic laboratory tests( BBL TM Clostridium Difficile Selective Agar , n.d.; Burnham & Carroll, 2013; Crobach et al, 2016; Gateau et al, 2018; Humphries et al, 2013; Lee et al, 2021; Litvin et al, 2009; Martínez-Meléndez et al, 2017; McDonald et al, 2018; Rodriguez et al, 2016; Tenover et al, 2011), contradicting results between cultivation and toxin detection assays(T. Parks et al, 2011) and an excessive reliance on single molecular tests(Polage et al, 2015). Recommended guidelines discourage stand-alone tests for CDI diagnosis and recommend a two-step procedure(Crobach et al, 2016; Gateau et al, 2018), but due to costs, test availability, capacity and turnaround times, diagnostic algorithms vary between hospitals and often deviate from recommended procedures(Tenover et al, 2011).…”

Diagnostic deficiencies of C. difficile infection among patients in a tertiary hospital in Saudi Arabia: A laboratory-based case series

“…Enterococcus faecalis is an enterococcus, a nosocomial pathogen that has similar risk factors as C. difficile including antibiotic treatment and hospitalization ( Özsoy and İlki, 2017 ). This Vancomycin-Resistant Enterococcus faecalis (VRE) is often detected in the C. difficile toxin positive samples ( Rodriguez et al, 2016 ). Therefore, based on the above results comparing two different methods for detecting C. difficile , we are reporting herein the recovery of nine bacterial species belonging to different genera on the C. difficile culture medium.…”

Clinical application of a multiplex genetic pathogen detection system remaps the aetiology of diarrhoeal infections in Shanghai

“…These limitations include the requirement of up to several days of growth before analysis, requirement of variable media and culture conditions for various species, problems associated with overgrowth of non-pathogenic bacteria that are abundant in the gut, and limited sensitivity due to technical limitations of incubation environments. Finally, a number of strictly anaerobic but important bacterial species, such as C. difficile are difficult to be cultured under routine laboratory conditions due to the requirement of specific equipment [ 30 , 31 ]. Detection of viruses is commonly conducted by singleplex real-time PCR.…”