Enhanced surveillance of non-O157 verotoxin-producing Escherichia coli in human stool samples from Manitoba.

Background: Relatively few enhanced surveillance studies have been undertaken to investigate the extent to which verotoxin-producing non-O157 serotypes of Escherichia coli occur in stool samples received for the detection of verotoxin-producing organisms.

Objectives: To describe the prevalence, molecular and epidemiological characteristics, and geographical patterns associated with non-O157 verotoxin-producing E coli (VTEC) in Manitoba.

Results: Thirty-two VTEC isolates consisting of 10 serogroups and 13 different serotypes were isolated over a 22-month period.

Increase in ampC promoter strength due to mutations and deletion of the attenuator in a clinical isolate of cefoxitin-resistant Escherichia coli as determined by RT-PCR.

Objectives: To characterize the mechanism of cefoxitin resistance in clinical isolate Escherichia coli N99-0001.

Methods: Plasmid analysis, PCR for beta-lactamases, and sequencing of the ampC genes was carried out. An RT-PCR method was developed to determine relative ampC expression.