Infection of Hamsters with Epidemiologically Important Strains of<i>Clostridium difficile</i>

Sambol, Susan P.; Tang, Janet K.; Merrigan, Michelle M.; Johnson, Stuart; Gerding, Dale N.

doi:10.1086/320736

Cited by 103 publications

(113 citation statements)

References 21 publications

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“…Nevertheless, previous studies characterized various levels of intrinsic virulence in C. difficile, classifying toxigenic strains as highly or less virulent in the hamster model (12). These different virulence potentials of strains, however, could not be confirmed by other researchers (44), who were unable to discriminate in the hamster model between toxigenic strains with various levels of postulated virulence in humans. In our MLST (1,8,9).…”

Section: Discussionmentioning

confidence: 89%

Multilocus Sequence Typing Analysis of Human and Animal Clostridium difficile Isolates of Various Toxigenic Types

et al. 2004

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A multilocus sequence typing (MLST) scheme was developed to study the genetic relationships and population structure of 72 Clostridium difficile isolates from various hosts, geographic sources, PCR ribotypes, and toxigenic types (determined by PCR targeting tcdA and tcdB genes). MLST was performed by DNA sequence analysis of seven housekeeping genes (aroE, ddl, dutA, tpi, recA, gmk, and sodA). The number of alleles ranged from five (dutA and ddl) to eleven (recA). Allelic profiles allowed the definition of 34 different sequence types (STs). These STs lacked correlation with geographic source but were well correlated to toxigenic type. The dendrogram generated from a matrix of pairwise genetic distances showed that animal isolates did not constitute a distinct lineage from human isolates and that there was no hypervirulent lineage within the population of toxigenic human isolates (isolates recovered from pseudomembranous colitis and antibioticassociated diarrhea did not cluster in distinct lineages). However, A ؊ B ؉ variant isolates shared the same ST that appeared as a divergent lineage in the population studied, indicating a single evolutionary origin. The population structure was further examined by analysis of allelic polymorphism. The dendrogram generated from composite sequence-based analysis revealed a homogeneous population associated with three divergent lineages, one of which was restricted to A ؊ B ؉ variant isolates. C. difficile exhibited a clonal population structure, as revealed by the estimation of linkage disequilibrium (Ia) between loci. The analysis of alleles within clonal complexes estimated that point mutation generated new alleles at a frequency eightfold higher than recombinational exchange, and the congruence of the dendrograms generated from separate housekeeping loci confirmed the mutational evolution of this species.

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Section: Discussionmentioning

confidence: 89%

Multilocus Sequence Typing Analysis of Human and Animal Clostridium difficile Isolates of Various Toxigenic Types

et al. 2004

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“…C. difficile spores for virulence assays were prepared as previously described (28). Briefly, cells were grown on TY plates for 5 days.…”

Section: Methodsmentioning

confidence: 99%

“…For pathogenesis assays, C. difficile spores were prepared as previously described (28). The number of viable spores was determined by plating on TY medium containing 0.1% taurocholate and 1% cysteine (15).…”

Section: Methodsmentioning

confidence: 99%

Identification and Characterization of a Gene Cluster Required for Proper Rod Shape, Cell Division, and Pathogenesis in Clostridium difficile

et al. 2014

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Little is known about cell division in Clostridium difficile, a strict anaerobe that causes serious diarrheal diseases in people whose normal intestinal microbiome has been perturbed by treatment with broad-spectrum antibiotics. Here we identify and characterize a gene cluster encoding three cell division proteins found only in C. difficile and a small number of closely related bacteria. These proteins were named MldA, MldB, and MldC, for midcell localizing division proteins. MldA is predicted to be a membrane protein with coiled-coil domains and a peptidoglycan-binding SPOR domain. MldB and MldC are predicted to be cytoplasmic proteins; MldB has two predicted coiled-coil domains, but MldC lacks obvious conserved domains or sequence motifs. Mutants of mldA or mldB had morphological defects, including loss of rod shape (a curved cell phenotype) and inefficient separation of daughter cells (a chaining phenotype). Fusions of cyan fluorescent protein (CFP) to MldA, MldB, and MldC revealed that all three proteins localize sharply to the division site. This application of CFP was possible because we discovered that O 2 -dependent fluorescent proteins produced anaerobically can acquire fluorescence after cells are fixed with cross-linkers to preserve native patterns of protein localization. Mutants lacking the Mld proteins are severely attenuated for pathogenesis in a hamster model of C. difficile infection. Because all three Mld proteins are essentially unique to C. difficile, they might be exploited as targets for antibiotics that combat C. difficile without disrupting the intestinal microbiome.C lostridium difficile is a strictly anaerobic, Gram-positive, spore-forming bacterium that has become the leading cause of hospital-acquired diarrhea in developed countries. The annual impact of C. difficile infections in the United States has been estimated at 14,000 deaths and over $1 billion in excess medical costs (1). Both the severity and the frequency of C. difficile infections are increasing (2), and a recent report on the impact of antibiotic resistance classified the organism as an "urgent threat," the highest threat level (1).C. difficile infections typically occur in people who have been treated with antibiotics that disrupt the flora of the gastrointestinal tract (3, 4). Although C. difficile is resistant to many antibiotics, the infection usually resolves upon treatment with metronidazole or oral vancomycin (5). Unfortunately, disease recurs in ϳ20% of patients, and the prognosis for this cohort is poor (4, 6, 7). The high rate of recurrence has been attributed to germination of C. difficile spores after antibiotic therapy is ended but before restoration of the normal flora (2, 8). For this reason, there is interest in developing antibiotics that target C. difficile selectively and in treatments such as fecal transplants which work by restoring a healthy microbiome (4, 7, 9, 10).Here we describe a cluster of three genes found in C. difficile that is important for morphogenesis, cell division, and pathogenesis. W...

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“…Of the microorganisms associated with HAI, Clostridium difficile (C. difficile) (Malamou-Ladas et al, 1983, Kim et al, 1981 represents the most significant disinfection challenge due to: the innate disinfection resistance of C. difficile spores (Tumah, 2009, Maillard, 2011, their environmental persistence (Kramer et al, 2006), the large numbers of spores excreted (Mulligan et al, 1979) and their low infective dose (Sambol et al, 2001). The requirement for disinfectants able to inactivate C. difficile spores, and the limited number of sporicides (Tumah, 2009, Lambert, 2004, has resulted in the domination of chlorine based products (Vohra andPoxton, 2011, Fraise, 2011).…”

Section: Introductionmentioning

confidence: 99%

A systematic evaluation of a peracetic-acid-based high performance disinfectant

Humphreys

Finan

Rout

et al. 2013

Journal of Infection Prevention

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The importance of environmental contamination in the spread of HAI has generated a need for high performance disinfectants. Currently chlorine based disinfectants are the products of choice, a position reflected in UK guidance. The aim of this research was to evaluate a peracetic acid (PAA) generating disinfectant to determine if it provided a realistic alternative to commonly used chlorine based disinfectants. The European standards framework was employed in this study and enhanced where appropriate by reducing the contact times, increasing the organic and microbial challenge, and changing the organisms involved. When tested against bacteria and spores PAA provided similar or better performance than currently employed levels of chlorine. This was particularly the case in the presence of an organic challenge or dried surface contamination. The chlorine disinfectants only demonstrated superior performance in the case of fungal spores. These results suggest that PAA generating products provide an effective alternative to chlorine based products up to 10,000 ppm free available chlorine. These products have superior performance in situations with spore borne, surface contamination and high organic challenge. In cases where filamentous fungi are a concern, high levels of PAA (>5000 ppm) would be required to match the performance of chlorine based disinfectants.

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Infection of Hamsters with Epidemiologically Important Strains ofClostridium difficile

Cited by 103 publications

References 21 publications

Multilocus Sequence Typing Analysis of Human and Animal Clostridium difficile Isolates of Various Toxigenic Types

Multilocus Sequence Typing Analysis of Human and Animal Clostridium difficile Isolates of Various Toxigenic Types

Identification and Characterization of a Gene Cluster Required for Proper Rod Shape, Cell Division, and Pathogenesis in Clostridium difficile

A systematic evaluation of a peracetic-acid-based high performance disinfectant

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