To review experience with methicillin-resistant Staphylococcus aureus (MRSA) in tertiary acute-care teaching hospitals on the Canadian prairies.

Retrospective review for a 36-month period, 1990 through 1992.

Five tertiary acute-care teaching hospitals in three Canadian prairie provinces.

MRSA isolates and susceptibility were identified through the clinical microbiology laboratory at each institution. For each patient, data collected included duration of institutional residence prior to isolation, patient ethnic background, age, sex, and antimicrobial susceptibility. Epidemiologic typing of strains used restriction fragment length polymorphism analysis by pulsed-field gel electrophoresis.

Two hundred fifty-nine MRSA isolates were identified in 135 patients during the 36 months, with substantial institutional variation in number of isolates. No consistent increase in yearly numbers of isolates was apparent. Patients usually had MRSA identified at admission (62%); only one of five centers had the majority of isolates acquired nosocomially. Patients with MRSA present at admission were more frequently of aboriginal (First Nations) ethnicity (62% compared with 14% of nosocomial; P<0.001). Pulsed-field gel electrophoresis of 167 isolates from 135 patients revealed 46 different strains with little interprovincial or inter-institutional identity of strains.

MRSA isolated in patients in tertiary care institutions in these three Canadian provinces usually is acquired prior to admission. A disproportionate number of isolates are identified in aboriginal Canadians. Epidemiologic typing was consistent with a polyclonal origin of MRSA in this geographic area.

To assess the potential for nosocomial measles transmission by measuring seropositivity among healthcare workers in Utah.

Blood specimens were collected for measurement of measles IgG antibody by enzyme immunoassay (EIA). Individuals with undetectable or equivocal antibody levels were considered at risk for infection. Employees were grouped according to the decade of their birth, and analyses of serological findings were done by the Mantel-Haenszel chi-square test for trend.

The study was performed in a healthcare organization comprised of six urban and 10 rural hospitals.

Employees (n = 5825) were tested regardless of age, history of disease, or immunization.

There were 599 employees (10.3%) who were nonimmune. A trend showing age-related differences in immunity was not noted among employees born prior to 1957 (4.7% nonimmune). However, for employees born after that time, there was a significant age-associated increase in the percentage of susceptible individuals (P= 0.00001). The rate of susceptibility was 8.1% for individuals born between 1957 and 1959, 16.3% for individuals born during the 1960s, and 33.7% for those born in the 1970s.

We concluded that employees born after 1960 represent a material risk for transmission of measles in the hospital setting. Despite the low percentage of susceptibility among those born before 1957, the 144 susceptible individuals in this group also are at risk for measles transmission. Thus, during periods of increased measles prevalence, we would recommend screening all healthcare workers regardless of age and vaccinating those who are susceptible.

To understand the epidemiology, risks, and management of Clostridium difficile -associated disease (CDAD) and to establish and evaluate reliable methods of surveillance.

Case finding was done by daily ward and laboratory rounds. The criteria for CDAD diagnosis were: at least four unformed stools per day for 2 days and a positive culture or cytotoxin for C difficile, or positive endoscopy or autopsy for pseudomembranes.

The surveillance covered all patients from 1982 through 1991 in the 820-bed Minneapolis Veterans Affairs Medical Center.

The criteria were met by 908 patients. Medical service patients numbered 488; surgical patients, 420. Frequencies ranged from a high of 149 cases in 1982 to a low of 50 cases in 1989.

Stool specimens were obtained on 898 (99%) of the 908 CDAD patients. Stools were culture-positive in 864 (96%) of 898, cytotoxin-positive in 569 (63%) of 898. Endoscopy was performed on 196 (22%) of the 908 patients, and 80 (41%) of 196 patients had pseudomembranes. Ten (1%) of the 908 patients were diagnosed by endoscopy without a stool specimen, or at autopsy. No treatment was needed for 135 (15%) of the 908 CDAD patients, and 19 (2%) of the 908 died before treatment was started. Oral metronidazole was the treatment for 632 (70%) of 908 patients (1% intolerance, 2% failure, 7% relapse) and oral vancomycin was given to 122 (13%) of 908 patients (1% intolerance, 1% failure, 10% relapse). Twelve patients had pseudomembranous colitis at autopsy, and it was the primary cause of death in 5 (0.6%) of 908.

CDAD usually responds to oral metronidazole or vancomycin but is nonetheless responsible for a high morbidity and occasional mortality in patients even when the diagnosis and treatment are pursued aggressively.