Molecular analysis of Clostridium difficile PCR ribotype 027 isolates from Eastern and Western Canada.

The prevalence and characteristics of PCR ribotype 027 strains of Clostridium difficile have come into question following recent outbreaks in Eastern Canada and elsewhere. In order to determine the distribution of this strain in other regions in Canada, we screened a bank of 1,419 isolates recovered from three different Canadian health regions between 2000 and 2004. Among isolates from a Montreal area hospital, PCR ribotype 027 strains represented 115/153 strains (75.2%) from 2003 to 2004, but ribotype 027 strains were absent in 2000 and 2001. In Calgary, by contrast, ribotype 027 rates have remained relatively stable over 4 years of surveillance, representing 51/685 (7.4%) hospital isolates and 62/373 (16.6%) strains from the community (P < 0.001). PCR ribotype 027 accounted for 8/135 (5.9%) hospital isolates in the Fraser Health Region in 2004. repetitive extragenic palindromic PCR was used to subtype a random selection of 027 isolates from each region. All 10 of the isolates from Quebec were of a single subtype, which was also dominant among isolates from Alberta (8/10 isolates) and British Columbia (6/8 isolates). Comparative sequencing of the tcdC repressor gene confirmed the documented 18-bp deletion and identified a second, single-base-pair deletion at position 117. Both deletions were conserved across all three provinces and were identified in a United Kingdom reference strain. The presence of a frameshift in the early portion of the tcdC gene implies serious functional disruption and may contribute to the hypervirulence of the 027 phenotype. PCR ribotype 027 strains appear to be widely distributed, to predate the Montreal outbreak, and to have measurable community presence in Western Canada.

An Outbreak of Human Coronavirus OC43 Infection and Serological Cross-reactivity with SARS Coronavirus.

BACKGROUND: In summer 2003, a respiratory outbreak was investigated in British Columbia, during which nucleic acid tests and serology unexpectedly indicated reactivity for severe acute respiratory syndrome coronavirus (SARS-CoV). METHODS: Cases at a care facility were epidemiologically characterized and sequentially investigated for conventional agents of respiratory infection, SARS-CoV and other human CoVs. Serological cross-reactivity between SARS-CoV and human CoV-OC43 (HCoV-OC43) was investigated by peptide spot assay. RESULTS: Ninety-five of 142 residents (67%) and 53 of 160 staff members (33%) experienced symptoms of respiratory infection. Symptomatic residents experienced cough (66%), fever (21%) and pneumonia (12%). Eight residents died, six with pneumonia. No staff members developed pneumonia. Findings on reverse transcriptase-polymerase chain reaction assays for SARS-CoV at a national reference laboratory were suspected to represent false positives, but this was confounded by concurrent identification of antibody to N protein on serology. Subsequent testing by reverse transcriptase-polymerase chain reaction confirmed HCoV-OC43 infection. Convalescent serology ruled out SARS. Notably, sera demonstrated cross-reactivity against nucleocapsid peptide sequences common to HCoV-OC43 and SARS-CoV. CONCLUSIONS: These findings underscore the virulence of human CoV-OC43 in elderly populations and confirm that cross-reactivity to antibody against nucleocapsid proteins from these viruses must be considered when interpreting serological tests for SARS-CoV.