Molecular epidemiology of endemic Clostridium difficile infection

Abstract

SUMMARYThis is the first study to provide a comprehensive insight into the molecular epidemiology of endemic Clostridium difficile and particularly that associated with a recently recognized epidemic strain. We DNA fingerprinted all C. difficile isolates from the stools of patients with symptomatic antibiotic-associated diarrhoea and from repeated samples of the inanimate ward environment on two elderly medicine hospital wards over a 22-month period. Notably, C. difficile was not recoverable from either ward immediately before opening, but was found on both wards within 1-3 weeks of opening, and the level of environmental contamination rose markedly during the first 6 months of the study period. C. difficile infection (CDI) incidence data correlated significantly with the prevalence of environmental C. difficile on ward B (r l 0n76, P 0n05) but not on ward A (r l 0n26, P 0n05). We found that RAPD and RS-PCR typing had similar discriminatory power, although, despite fingerprinting over 200 C. difficile isolates, we identified only six distinct types. Only two distinct C. difficile strains were identified as causing both patient infection and ward contamination. Attempts to determine whether infected patients or contaminated environments are the prime source for cross-infection by C. difficile had limited success, as over 90 % of C. difficile isolates were the UK epidemic clone. However, a non-epidemic strain caused a cluster of six cases of CDI, but was only isolated from the environment after the sixth patient became symptomatic. The initial absence of this strain from the environment implies patient-to-patient and\or staff-to-patient spread. In general, routine cleaning with detergent was unsuccessful at removing C. difficile from the environment. Understanding the epidemiology and virulence of prevalent strains is important if CDI is to be successfully controlled.

Clostridium difficile in a geriatric unit: a prospective epidemiological study employing a novel S-layer typing method

“…The seven other S/toxin-types and the untypable colonized a comparatively small number of patients. These findings were similar to those from a study carried out by Fawley & Wilcox (2001). Their study investigated the patients and the environment of two elderly general medicine wards over a 22-month period.…”

“…These data from both the RVH and Fawley & Wilcox (2001) suggest that an increase in the number of colonized patients can lead to an increase in the levels of environmental contamination with the colonizing strain. Fawley & Wilcox (2001) also suggested that initial cross-infection from patient to patient or from staff to patient may occur before heavy environmental contamination occurs and causes further crosscontamination. This may perhaps explain the transfer of Stype 5438 between patients in different bays within ward A.…”

“…All the patients colonized with this strain were housed in different bays, suggesting that contamination of the environment may not have been directly responsible if cross-infection occurred with this strain. In the study by Fawley & Wilcox (2001), they reported that a particular genotype was not isolated from the environment until the sixth patient in a cluster of cases became symptomatic. These data from both the RVH and Fawley & Wilcox (2001) suggest that an increase in the number of colonized patients can lead to an increase in the levels of environmental contamination with the colonizing strain.…”

“…In the study by Fawley & Wilcox (2001), they reported that a particular genotype was not isolated from the environment until the sixth patient in a cluster of cases became symptomatic. These data from both the RVH and Fawley & Wilcox (2001) suggest that an increase in the number of colonized patients can lead to an increase in the levels of environmental contamination with the colonizing strain. Fawley & Wilcox (2001) also suggested that initial cross-infection from patient to patient or from staff to patient may occur before heavy environmental contamination occurs and causes further crosscontamination.…”

Clostridium difficile infection in elderly nursing home residents

“…There are few studies that refer to the presence of C. difficile in the environment of elderly patient hospital wards [4,27,28]. Contaminated areas of the environment such as floors, electronic thermometers and even the air can contribute towards C. difficile transmission in healthcare settings [4,29].…”