Identification of Clostridium difficile: evaluation of genotypic, phenotypic and proteomic methods

Toxigenic Clostridium difficile colonization among hospitalised adults; risk factors and impact on survival

OBJECTIVES

To establish risk factors for Clostridium difficile colonization among hospitalized patients in England.

METHODS

Patients admitted to elderly medicine wards at three acute hospitals in England were recruited to a prospective observational study. Participants were asked to provide a stool sample as soon as possible after enrolment and then weekly during their hospital stay. Samples were cultured for C. difficile before ribotyping and toxin detection by PCR. A multivariable logistic regression model of risk factors for C. difficile colonization was fitted from univariable risk factors significant at the p < 0.05 level.

RESULTS

410/727 participants submitted ≥1 stool sample and 40 (9.8%) carried toxigenic C. difficile in the first sample taken. Ribotype 106 was identified three times and seven other ribotypes twice. No ribotype 027 strains were identified. Independent predictors of colonization were previous C. difficile infection (OR 4.53 (95% C.I. 1.33-15.48) and malnutrition (MUST score ≥2) (OR 3.29 (95% C.I. 1.47-7.35)). Although C. difficile colonised patients experienced higher 90-day mortality, colonization was not an independent risk for death.

CONCLUSIONS

In a non-epidemic setting patients who have previously had CDI and have a MUST score of ≥2 are at increased risk of C. difficile colonization and could be targeted for active surveillance to prevent C. difficile transmission.

Prevalence and molecular types of Clostridium difficile isolates from faecal specimens of patients in a tertiary care centre

Clostridium difficile infection (CDI) leads to considerable morbidity and mortality among hospitalized patients. Faecal specimens from 1110 hospitalized patients suspected for CDI were cultured for isolation of C. difficile and characterization of virulence genes. PCR was carried out for toxigenic genes tcdA, tcdB, cdtA and cdtB and PCR-RFLP for fliC and slpA genes. Of 174 (15.7%) C. difficile isolates, 121 (69.5%) were toxigenic, amongst which 68 (56.2%) also had both tcdA and tcdB genes. The remaining 53 (43.8%) of the isolates also had at least one of the toxin genes. Binary toxin genes (cdtA and cdtB) with only one of the two components were present in 16 (9.2%) of the 174 isolates. The other virulence genes - fliC and slpA - were present in 100% of the isolates. The most frequent PCR-RFLP type of fliC gene was type I (n = 101), followed by type VII (n = 49) and type III (n = 24). The slpA gene presented with three combinations of patterns. Characterization of virulence genes in C. difficile isolates is of extreme importance for epidemiological surveillance and control of outbreaks owing to the capacity of this bacterium to adapt to new environmental circumstances, leading to the emergence of new epidemic strains.