Barbara M. Willey

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A major outbreak involving an Escherichia coli strain that was resistant to expanded-spectrum cephalosporins occurred in Toronto and surrounding regions in 2000 to 2002. We report the complete sequence of a plasmid, pC15-1a, that was found associated with the outbreak strain. Plasmid pC15-1a is a circular molecule of 92,353 bp consisting of two distinct(More)
Understanding the fine-structure molecular architecture of bacterial epidemics has been a long-sought goal of infectious disease research. We used short-read-length DNA sequencing coupled with mass spectroscopy analysis of SNPs to study the molecular pathogenomics of three successive epidemics of invasive infections involving 344 serotype M3 group A(More)
Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from nares of 27/417 (6.5%) attendees at an international veterinary conference: 23/345 (7.0%) veterinarians, 4/34 (12.0%) technicians, and 0/38 others. Colonization was more common for large-animal (15/96, 15.6%) than small-animal personnel (12/271, 4.4%) or those with no animal patient(More)
Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging equine pathogen. To attempt to control nosocomial and zoonotic transmission, an MRSA screening program was established for all horses admitted to the Ontario Veterinary College Veterinary Teaching Hospital, whereby nasal screening swabs were collected at admission, weekly during(More)
Many pathogens colonize different anatomical sites, but the selective pressures contributing to survival in the diverse niches are poorly understood. Group A Streptococcus (GAS) is a human-adapted bacterium that causes a range of infections. Much effort has been expended to dissect the molecular basis of invasive (sterile-site) infections, but little is(More)
Clostridium difficile is the bacterium most commonly surmised to cause antimicrobial- and hospital-associated diarrhea in developed countries worldwide, and such infections are thought to be increasing in frequency and severity. A laboratory-based study was carried out to characterize C. difficile strains isolated from persons in Ontario, Canada, during(More)
Enterococci, a common cause of nosocomial infection, are intrinsically resistant to most antimicrobials and readily acquire additional resistance. Vancomycin-resistant enterococci (VRE) have caused clusters of nosocomial infections since 1988. In April, 1991, the New York City Department of Health asked all city laboratories to submit suspected VRE isolates(More)
OBJECTIVE To describe MRSA infection and colonization in household pets, and transmission of MRSA between animals and humans. METHODS MRSA infection and colonization in household pets and human contacts were evaluated during investigations initiated after identification of MRSA infection or colonization of a household pet in order to determine if there(More)
OBJECTIVE To evaluate the prevalence of nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) in horses and horse personnel. DESIGN Prospective prevalence study. SAMPLE POPULATION 972 horses and 107 personnel from equine farms in Ontario, Canada and New York state. PROCEDURE Nasal swab specimens were collected from horses and(More)
Methicillin-resistant Staphylococcus aureus (MRSA) carriage and subsequent infection were prospectively compared among a well-defined group of 107 individuals infected with human immunodeficiency virus type 1 (HIV-1) who had no evidence of immune suppression and 52 epidemiologically matched, uninfected individuals. The carriage strains and infecting strains(More)