Dataset Information

Variation in germination of Clostridium difficile clinical isolates correlates to disease severity.

ABSTRACT: Over the past two decades, Clostridium difficile infections have been increasing in both number and severity throughout the world. As with other spore forming bacteria, germination is a vital step in the life cycle of this pathogen. Studies have examined differences in sporulation and toxin production among a number of C. difficile clinical isolates; however, few have examined differences in germination and the relationship between this phenotype and disease severity. Here, over 100 C. difficile isolates from the University of Michigan Health System were examined for overall germination in response to various combinations of known germinants (taurocholate) and co-germinants (glycine and histidine). Significant variation was observed among isolates under all conditions tested. Isolates representing ribotype 014-020, which was the most frequently isolated ribotype at our hospital, exhibited increased germination in the presence of taurocholate and glycine when compared to isolates representing other ribotypes. Interestingly, isolates that caused severe disease exhibited significantly lower germination in response to minimal germination conditions (taurocholate only), indicating increased control over germination in these isolates. These data provide a broad picture of C. difficile isolate germination and indicate a role for precise control of germination in disease severity.

SUBMITTER: Carlson PE

PROVIDER: S-EPMC4467518 | biostudies-literature | 2015 Jun

REPOSITORIES: biostudies-literature

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Variation in germination of Clostridium difficile clinical isolates correlates to disease severity.

Carlson Paul E PE Kaiser Alyssa M AM McColm Sarah A SA Bauer Jessica M JM Young Vincent B VB Aronoff David M DM Hanna Philip C PC

Anaerobe 20150211

Over the past two decades, Clostridium difficile infections have been increasing in both number and severity throughout the world. As with other spore forming bacteria, germination is a vital step in the life cycle of this pathogen. Studies have examined differences in sporulation and toxin production among a number of C. difficile clinical isolates; however, few have examined differences in germination and the relationship between this phenotype and disease severity. Here, over 100 C. difficile ...[more]

PMID: 25681667

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Project description:Rifaximin, a poorly absorbed rifamycin derivative, is a promising alternative for the treatment of Clostridium difficile infections. Resistance to this agent has been reported, but no commercial test for rifaximin resistance exists and the molecular basis of this resistance has not been previously studied in C. difficile. To evaluate whether the rifampin Etest would be a suitable substitute for rifaximin susceptibility testing in the clinical setting, we analyzed the in vitro rifaximin susceptibilities of 80 clinical isolates from our collection by agar dilution and compared these results to rifampin susceptibility results obtained by agar dilution and Etest. We found rifaximin susceptibility data to agree with rifampin susceptibility; the MICs of both antimicrobials for all isolates were either very low or very high. Fourteen rifaximin-resistant (MIC, > or = 32 microg/ml) unique isolates from patients at diverse locations in three countries were identified. Molecular typing analysis showed that nine (64%) of these isolates belonged to the epidemic BI/NAP1/027 group that is responsible for multiple outbreaks and increased disease severity in the United Kingdom, Europe, and North America. The molecular basis of rifaximin and rifampin resistance in these isolates was investigated by sequence analysis of rpoB, which encodes the beta subunit of RNA polymerase, the target of rifamycins. Resistance-associated rpoB sequence differences that resulted in specific amino acid substitutions in an otherwise conserved region of RpoB were found in all resistant isolates. Seven different RpoB amino acid substitutions were identified in the resistant isolates, which were divided into five distinct groups by restriction endonuclease analysis typing. These results suggest that the amino acid substitutions associated with rifamycin resistance were independently derived rather than disseminated from specific rifamycin-resistant clones. We propose that rifaximin resistance in C. difficile results from mutations in RpoB and that rifampin resistance predicts rifaximin resistance for this organism.

Dataset Information

Variation in germination of Clostridium difficile clinical isolates correlates to disease severity.

Publications

Variation in germination of Clostridium difficile clinical isolates correlates to disease severity.

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