The impact of diagnostic methods on the diagnosis of Clostridiodes difficile infection

Abstract

Clostridiodes difficile is a common cause of healthcare-associated diarrhoea. The clinical outcome depends on host factors and the virulence of the toxin-producing strain. This organism causes disease that ranges in severity from asymptomatic colonisation to severe diarrhoea, pseudomembranous colitis, toxic megacolon, colonic perforation and death. [1-3] The principal risk factor for C. difficile infection (CDI) is prior antibiotic therapy. [4] Results of a systematic review assessing the epidemiology of CDI in low and middle Human Development Index countries show that there is a paucity of published literature describing the epidemiology and burden of CDI. [2] Rajabally et al. [1,3] highlight that data relating to the burden of C. difficile-associated disease (CDAD) in southern Africa are limited. The study conducted by this group emphasises that the magnitude of the CDI burden in South African (SA) hospitals is not known. [1,3] Freeman et al. [5] note the two key issues that hinder understanding of the epidemiology of CDI. Firstly, there is poor recognition and documentation of CDAD. [5] The second obstacle is the many different approaches to the laboratory diagnosis of CDI. This is a dilemma also encountered in SA. [5] There are numerous targets and combinations of targets that can be used to detect C. difficile (cell cytotoxicity assays (CCAs), toxigenic culture, glutamate dehydrogenase (GDH), toxins through enzyme immunoassay (EIA), and toxin genes through polymerase chain reaction (PCR)). Researchers in the UK have noted a variation in the reference standards for CDI diagnosis. This variation gives rise to differences in assessment of the diagnostic performance of assays and contributes to uncertainty in diagnosing CDI. [6,7] It is therefore likely that the measured incidence of infection will vary according to the laboratory diagnostic method used. [5-7] PCR-based testing is unable to differentiate between infection and colonisation. As a result, reliance on it as a stand-alone test may result in over-diagnosis of CDI. [3] The low sensitivity of toxin EIAs also makes these unsuitable as stand-alone tests. [3,6] For this reason, an algorithm that includes a sensitive assay (GDH or PCR) followed by a specific assay (toxin detection) may provide more accurate results. [8] The Society for Healthcare Epidemiology of America (SHEA), the Infectious Diseases Society of America (IDSA) and the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) all recommend the use of multistep algorithms for the diagnosis of CDI. [8,9] These algorithms allow reliable exclusion of CDI without additional tests if the GDH screen or PCR is negative, [8] reducing the turnaround time significantly while providing accurate results. [8,9] Objectives Prior to July 2016, the Charlotte Maxeke Johannesburg Academic Hospital (CMJAH) Microbiology Laboratory used stand-alone PCR and stand-alone toxin EIA for CDI diagnosis. Currently, a two-step algorithm for CDI diagnosis is used. A rapid EIA for GDH and toxin A/B is the i...

Comparison of commercial assays and two-step approach to detect Clostridioides difficile in South Africa

“…In a study conducted 2014–2017 in South Africa demonstrated the impact of diagnostic methods on the diagnosis of C. difficile infection, Nomlomo et al found a 15.9% positivity rate when using an algorithm approach (consisting of EIA followed by PCR) versus 11.4% and 21.1% when using a toxin EIA and PCR. 27 However, neither of the two accepted references tests was performed as the comparator test in this study. We showed a 16.6% TC positivity rate which is very similar to Nomlomo et al’s finding using the algorithm approach.…”

“…We showed a 16.6% TC positivity rate which is very similar to Nomlomo et al’s finding using the algorithm approach. 27 …”

Effect of Tanshinone IIA on Gut Microbiome in Diabetes-Induced Cognitive Impairment

“…C. difficile , a Gram-positive bacteria, is suggested to cause pseudomembranous colitis, swelling or inflammation of the colon ( Nomlomo and Nana, 2020 ). A retrospective study of the Nationwide Readmissions Database in the United States suggested that diabetes mellitus correlates to 30-day all-cause readmissions for C. difficile –induced enterocolitis ( Kichloo et al, 2022 ).…”