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Medycyna Doświadczalna i Mikrobiologia 2015, 67(1): 9-14

Ocena wzrostu na podłożu chromID C. difficile Agar klinicznych szczepów Clostridium difficile należących do różnych PCR-rybotypów
[Evaluation of growth of clinical Clostridium difficile strains belonging to different PCR-ribotypes on chromID C. difficile Agar]

Paweł Karpiński, Hanna Pituch, Dominika Lachowicz, Michał Piotrowski, Piotr Obuch-Woszczatyński

Streszczenie.

Zastosowanie chromogennego podłoża ChromID C. difficile Agar do izolacji klinicznych szczepów Clostridium difficile przyspiesza wykrywanie tego patogenu w próbkach kału chorych z biegunką. Typowe szczepy C. difficile rosną na tym podłożu w postaci ciemnych kolonii. Jednak niektóre warianty mogą rosnąć nietypowo, w postaci jasnych kolonii, co może skutkować nierozpoznaniem tego patogenu. Odsetek polskich szczepów pochodzących z różnych źródeł, które rosły w postaci jasnych kolonii wyniósł ok. 6% i wszystkie należały do PCR-rybotypu 023.

Abstract.

Introduction: Clostridium difficile is main reason of antibiotic-associated diarrhea in hospitalized patients. Diagnostic method for detection of Clostridium difficile infection (CDI) are limited to an enzyme immunoassays (EIAs), while the culture of toxigenic strains is still seen as the gold standard for the laboratory diagnosis. The aim of this study was to compare growth of C. difficile strains belonging to different polymerase chain reaction (PCR) ribotypes on new ChromID C. difficile Agar (CDIFF, bioMérieux, Marcy l’Etoile, France).Materials and Methods: One hundred thirty one of clinical C. difficile strains stored in Anaerobic Laboratory were cultured on ChromID C. difficile Agar. Ten faecal samples were cultured on the same chromogenic medium and incubated at 37°C for 24 h under anaerobic conditions. Isolates were confirmed as C. difficile on the basis of well-known criteria. PCR-ribotyping was performed by visually comparison of patterns of PCR products of the 16S–23S rRNA intergenic spacer region. We examined the occurrence of beta-glucosidase gene, responsible for the dark color of the colony C. difficile on ChromID C.difficile Agar using a pair of primers: gluF (5’-AAGGT GTAAATTTAGGAGGTTGGTT-3’) i gluR (5’- GGTCCCAACTATCCC ATCC-3’). Results: Among ten C. difficile isolates obtained from stool specimens one formed colorless colonies. We received 8 colorless isolates from 131 additional examined strains. All C. difficile isolates forming colorless colonies belonged to PCR ribotype 023. The prevalence of PCR-ribotype 023 was about 6%. We detected lack of beta-glucosidase gene in PCR-ribotype 023 isolates. Conclusions: There are some C. difficile strains forming colorless colonies on ChromID C.difficile Agar. This appearance is important in routine diagnostic use this chromogenic culture medium. 

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