This study aimed to implement a toxigenic culture as an optional third diagnostic step for glutamate dehydrogenase (GDH)-positive and toxin A/B-negative diarrheal stool samples into a diagnostic algorithm for Clostridioides (Clostridium) difficile infection (CDI), and to characterise C. difficile isolates for epidemiological purposes. During the 5-month study, 481 diarrhoeal stool samples from three Slovak hospitals were investigated and 66 non-duplicated GDH-positive stool samples were found. Of them, 36 were also toxin A/B-positive. Twenty-three GDH-positive and toxin A/B-negative stool samples were shown subsequently to be positive following toxigenic culture (TC). Molecular characterisation of C. difficile isolates showed the predominance of PCR ribotype (RT) 001 (n = 37, 56.1%) and the occurrence of RT 176 (n = 3, 4.5%). C. difficile RT 001 isolates clustered to eight clonal complexes (CCs) using multiple-locus variable-number tandem repeats analysis (MLVA). Interestingly, one third of RT 001 isolates clustering in these CCs were cultured from toxin A/B-negative stool samples. Our observations highlight the need of use multiple step diagnostic algorithm in CDI diagnosis in order to detect all CDI cases and to avoid the spread of C. difficile in healthcare settings.

Department of Medical Microbiology 2nd Faculty of Medicine Charles University and Motol University Hospital 5 Uvalu 84 150 06 Prague 5 Czech Republic

Department of Microbiology Medirex Group Kosice Slovakia

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