Affiliation:
1. Department of Microbiology, Leeds Teaching Hospitals & University of Leeds, Leeds, United Kingdom
Abstract
ABSTRACT
We previously identified two subtypes of the epidemic strain
Clostridium difficile
PCR ribotype 1, one clindamycin-sensitive strain (arbitrarily primed PCR [AP-PCR] type Ia) and a closely related clindamycin-resistant strain (AP-PCR type Ib) in our institution. We have now carried out prospective epidemiological surveillance for 4 years, immediately following the relocation of two acute medicine wards for elderly patients (wards A and B), to determine the clinical epidemiology of subtypes of the epidemic
C. difficile
PCR ribotype 1 group. To maximize the chance of strain discrimination, we used three DNA fingerprinting methods, AP-PCR, ribospacer PCR (RS-PCR), and pulsed-field gel electrophoresis (PFGE), to analyze
C. difficile
isolates recovered from symptomatic patients and from repeated environmental samplings. On ward B the incidence of
C. difficile
infection correlated significantly with the prevalence of environmental
C. difficile
both in ward areas closely associated with patients and health care personnel (
r
= 0.53;
P
< 0.05) and in high-reach sites (
r
= 0.85;
P
< 0.05). No such relationships were found on ward A. Seventeen distinct
C. difficile
genotypes were identified, 17 by AP-PCR, 12 by PFGE, and 11 by RS-PCR, but only 4 of 17 genotypes caused patient infection. Isolates recovered from the hospital ward environment were much more diverse (14 genotypes). AP-PCR type Ia represented >90% of the
C. difficile
isolates. In addition to this genotype, only two others were isolated from both patient feces and environmental surfaces. AP-PCR type Ib (clindamycin-resistant PCR ribotype 1 clone) was not associated with any cases of
C. difficile
infection and was isolated from the environment on only two occasions, after having been implicated in a cluster of six
C. difficile
infections 5 months before this study. The disappearance of this strain implies that differences in virulence and/or selective pressures may exist for this strain and the closely related, widespread
C. difficile
AP-PCR type Ia strain. Our findings emphasize the need to understand the epidemiology and virulence of clinically significant strains to determine successful control measures for
C. difficile
infections.
Publisher
American Society for Microbiology
Cited by
36 articles.
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