To assess the cost-effectiveness of human immunodeficiency virus (HIV) screening strategies of surgeons and dentists.

We constructed a model to project costs and HIV transmissions prevented over 15 years for four screening scenarios: 1) one-time voluntary screening, 2) one-time mandatory screening, 3) annual voluntary screening, and 4) annual mandatory screening. One-time screening occurs only in the first year of the program; annual screening occurs once each year. Under mandatory screening, all practitioners are tested and risks of practitioner-to-patient transmission are eliminated for all practitioners testing positive. Voluntary screening assumes 90% of HIV-positive and 50% of HIV-negative practitioners are tested, and risks of transmission in the clinical setting are eliminated for 90% of HIV-positive surgeons and dentists. All costs and benefits are discounted at 5% per annum over 15 years.

Using “best-case” scenario assumptions, we find for surgeons that a one-time voluntary screening program would be most cost-effective, at $899,336 for every HIV transmission prevented. For dentists, the one-time voluntary program also is the most cost-effective, at $139,571 per transmission prevented. Annual mandatory programs were least cost-effective for both surgeons and dentists, at $63.3 million and $2.2 million per transmission prevented, respectively.

HIV screening of surgeons and dentists ranks among the more expensive medical lifesaving programs, even using liberal assumptions about program effectiveness. Frequency of screening and whether testing is mandatory or voluntary dramatically affect cost per transmission prevented; these features should be considered carefully in designing specific HIV screening programs.

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 report a pseudoepidemic of Pseudomonas aeruginosa infections discovered during an investigation of postoperative joint infections.

A retrospective review of case patients’ hospital charts, operative reports, and laboratory data, as well as environmental culturing, polymerase chain reaction (PCR) ribotyping of outbreak isolates, and in vitro analysis of P aeruginosa growth characteristics.

A 510-bed, university-affiliated adult tertiary care hospital.

Between October 1 and December 1, 1992, seven postsurgical joint infections were diagnosed, including four caused by P aeruginosa. A bottle of “sterile” saline used to process tissue specimens was found to be contaminated with P aeruginosa. Further investigation revealed that P aeruginosa had grown from seven additional tissue cultures, all of which had been processed with the contaminated saline. PCR ribotypes of the contaminant matched those of the clinical isolates. In vitro, P aeruginosa strains were viable in commercial nonbacteriostatic saline, but never caused visible turbidity.

Six patients received antibiotics for their presumed infections; four patients had peripherally inserted central catheters placed, and one experienced severe anaphylactic reactions to several antibiotics.

Pseudoepidemics due to common organisms are often difficult to detect, and delayed recognition can result in substantial morbidity. This outbreak investigation illustrates the potential for contamination of diluents in the microbiology laboratory and emphasizes the need for meticulous quality control.

To investigate coagulase-negative staphylococcus (CONS) causing bacteremia in a neonatal intensive care unit (NICU).

A 14-month retrospective review of 47 infants in the NICU with CONS bacteremia was undertaken to determine CONS glycocalyx production, plasmid pattern, total DNA restriction fragment polymorphism, and clinical risk factors.

The isolates included 32 Staphylococcus epidermidis, six Staphylococcus haemolyticus, four Staphylococcus warneri, four Staphylococcus saprophyticus, and one Staphylococcus hominis. Sixty-five percent of S epidermidis produced glycocalyx; other species did not. Oxacillin resistance (52%) and the antibiograms of the CONS were consistent with other units in the hospital. Five similar CONS plasmid patterns were found among 16 isolates; 31 isolates had unique patterns. Extractions of total DNA from these isolates were digested using HindIII, HaeIII, and BstEII. Those with similar restriction fragment length patterns could not be linked as nosocomially transmitted among infants with bacteremia.

Our observations suggest that multiple strains of CONS infect infants in the NICU who have similar risk factors. Although current infection control practices limit transmission of a pathogen, they do not prevent CONS bacteremias.