No abstract

Accurate diagnosis of Clostridium difficile infection is essential for disease management.A clinical and molecular analysis of C. difficile isolated from symptomatic patients at Groote Schuur Hospital, South Africa, was conducted to establish the most suitable clinical test for the diagnosis and characterization of locally prevalent strains. C. difficile was detected in stool samples using enzyme-based immunoassays (EIA) and nucleic acid amplification methods, and their performance was compared with that of C. difficile isolation using direct selective culture combined with specific PCR to detect the C. difficile tpi gene, toxin A and B genes and binary toxin genes. Toxigenic isolates were characterized further by ribotyping. Selective culture isolated 32 C. difficile strains from 145 patients (22 %). Of these, the most prevalent (50 %) were of ribotype 017 (toxin A 2 B + ) while 15.6 % were ribotype 001 (toxin A + B + ). No ribotype 027 strains or binary toxin genes (cdtA and cdtB) were detected. The test sensitivities and specificities, respectively, of four commercial clinical diagnostic methods were as follows: ImmunoCard Toxins A & B (40 % and 99.1 %), VIDAS C. difficile Toxin A & B (50 % and 99.1 %), GenoType CDiff (86.7 % and 88.3 %) and Xpert C. difficile (90 % and 97.3 %). Ribotype 001 and 017 strains had a 100 % detection rate by Xpert C. difficile, 100 % and 93.3 % by GenoType CDiff, 75 % and 53.3 % by ImmunoCard and 75 % and 60 % by VIDAS, respectively. The overall poor performance of EIA suggests that a change to PCR-based testing would assist diagnosis and ensure reliable detection of locally prevalent C. difficile 017 strains. INTRODUCTIONOver the last decade, Clostridium difficile infection (CDI) has emerged as an important healthcare problem, both in the hospital setting and in the community. There has been growing concern over its rising incidence, disease severity and mortality. Major epidemics, causing significant loss of lives, have been reported in North America and Europe (Birgand et al., 2010; Healthcare Commission, 2006; Pépin et al., 2004). These epidemics have been attributed to virulent strains capable of producing more than ten times the amount of toxins than conventional strains (Kelly & LaMont, 2008;McDonald et al., 2005;O'Connor et al., 2009). In addition, the 'hyper virulent' 027 strain has developed resistance to antibiotics such as fluoroquinolones (Pépin et al., 2005).In South Africa, information on CDI remains scarce. Yet, there are some studies that have shown that CDI in this Abbreviations: CA, community acquired; CDI, Clostridium difficile infection; EIA, enzyme-based immunoassays; GDH, glutamate dehydrogenase; HA, hospital acquired; NLR, negative likelihood ratio; NPV, negative predictive value; PLR, positive likelihood ratio; PPV, positive predictive value. part of the world is not insignificant. In 2008, an institution in Pretoria reported a sudden increase in toxin-producing C. difficile, raising the alert of a possible outbreak and sensitizing its clinicians (Lekala...

Background. Diarrhoea due to gastrointestinal infections is a significant problem facing the South African (SA) healthcare system. Infections can be acquired both from the community and from the hospital environment itself, the latter acting as a reservoir for potential pathogenic bacteria. Objectives. To examine the prevalence of a panel of potential diarrhoeacausing bacteria in patients attending a tertiary healthcare facility in Cape Town, SA. Methods. Polymerase chain reaction (PCR) primers specific for Clostridium difficile, Shigella spp., Salmonella spp., Klebsiella oxytoca, enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC/EHEC), Staphylococcus aureus, enterotoxigenic Bacteroides fragilis and Campylobacter spp. were used to screen total bacterial genomic DNA extracted from stool samples provided by 156 patients with diarrhoea attending Groote Schuur Hospital, Cape Town, SA. Results. C. difficile was the most frequently detected pathogen (16% of cases) in the 21 87yearold patient range, but was not present in samples from the 16 20yearold range. K. oxytoca (6%), EPEC/EHEC strains (9%) and S. aureus (6%) were also detected. The remaining pathogens were present at low frequencies (0 2.9%), and the occurrence of mixed infections was 5%. The majority of nonC. difficilerelated diarrhoeas were community acquired. Conclusion. C. difficile was the main cause of infectious diarrhoea in the sampled patients, while K. oxytoca and EPEC/EHEC strains were present as relatively minor but potentially significant pathogens.