To describe the occurrence and decline of methicillin-resistant Staphylocococcus aureus in Denmark from 1966 to 1986, and to illustrate why it has been possible to retain a frequency of only 0.2% MRSA since 1984.

A study of antibiotic susceptibility and phage-type of 522,978 S aureus strains isolated from hospitalized patients in Denmark during the years 1960 to 1988 combined with clinical information on patients with methicillin-resistant strains during the years 1986 through 1988.

All strains and information were collected at the centralized, national laboratory for S aureus phage-typing.

Hospitalized patients with S aureus isolates, and especially patients with meth-icillin-resistant strains.

Antibiotic treatment.

The frequency of MRSA rose to 15% in the years 1967 through 1971 but decreased to 0.2% in 1984, and has remained so ever since. The increase was due mainly to the spread of a single or a few clones of the phage-type complex 83A. Occurrence of strains of these phage-types declined from 18% in 1969 to 0.6% in 1989. In 1986 through 1988, at least 48% of the MRSA strains were imported by patients from abroad. Cross-infection occurred only in two cases. High awareness and special precautions were taken when MRSA was detected.

MRSA of a single or a few clones spread in Danish hospitals in the years 1967 through 1971. Since 1984, only 0.2% of the Danish S aureus population has been MRSA, and imported MRSA strains have been prevented from spreading. (Infect Control Hosp Epidemiol. 1991;12:83-88.)

Spirometry is a widely used pulmonary function test that allows measurement of forced vital capacity and time-related measures of dynamic pulmonary function. This study was designed to identify the risk of cross-transmission associated with two commonly used dry-rolling seal spirometers.

Using a prospective study design, we examined whether microbial contamination of spirometers occurred following use by patients with a heavily colonized or infected respiratory tract. Prior to spirometry evaluation, a patients sputum culture and equipment samples (i.e., mouthpiece, proximal tubing, piston surface) were obtained. After patient evaluation, a sterile 2 L ventilation bag and sterile tubing were used to simulate the risk of infection of subsequent patients. Simulation 1 was performed immediately after patient testing and Simulation 2, representing a second patient was conducted approximately 18 hours later.

This study was conducted at the University of North Carolina Hospitals, a large university teaching facility.

Fourteen patients with underlying pulmonary disease were studied.

Our study revealed that the mouthpieces became contaminated with the patients' oral flora and with the associated respiratory pathogen. Fourteen percent of the associated tubing after patient testing contained the respiratory pathogen. All other equipment samples (e.g., interior surfaces of the machine, Simulation 1, Simulation 2 samples) were negative for the respiratory pathogen.

These data suggest that mouthpieces and spirometry tubing may become contaminated with microorganisms and should not be shared between patients. Since there is little or no bacterial contamination of the surfaces inside the spirometers and cross transmission is unlikely, it is unnecessary to routinely clean the interior surfaces of the spirometers. (Infect Control Hosp Epidemiol. 1991;12:89-92.)

To determine the efficacy of a lanolin-based gel in preventing radioactive particle and viral penetration.

Paired, stacked filter discs were held in a stainless steel support, and the gel was applied manually to the upper surface of the upper filter. Indicator solution containing either radioactive viral particles (3H-labeled simian virus 40 or 3H-labeled woodchuck hepatitis virus) or 20 u1 or 100 u1 of 32P-labeled radioactive compounds of much lower molecular weight then were applied to the upper filter. The filter discs were separated after 30 minutes, and the lower disc was examined for radioactivity in a liquid scintillation counter.

Transmission of radioactive particles was statistically significantly reduced by the application of the ointment on the upper filter (from 6.7 ± 0.1 × 105 counts per minute [cpm] to 88 ± 38 cpm). Transmission of both labeled viral particles also was reduced to a similar degree.

Application of protective ointment to the filters significantly reduces transmission of radioactive viral particles and smaller radioactive compounds through filter discs. Use of this ointment may offer similar mechanical protection against the transmission of viruses between patient and healthcare provider. (Infect Control Hosp Epidemiol. 1991;12:93-95.)

This study identifies risk factors that predispose hospitalized patients to diarrhea caused by Clostridium difficile.

Unlike most previous studies, this case-control study accounts for horizontal (person-to-person) transmission of this infectious organism by matching on location.

An urban community hospital of 600 beds with both primary care and referred patients.

Both the 36 cases and the 36 controls came from billing printouts for C difficile cytotoxin assays. Exclusion criteria included outpatient specimens and stays of 38 days or more. Controls had negative assays and were individually matched on the basis of the floor and by the general date of specimen collection.

Cases had a longer mean duration of antibiotic use (6.7 versus 4.1 days, p = .006). Of the other 22 factors that were evaluated for their risk of predisposing to C difficile, only clindamycin (OR = 3.50, p =.09) and third-generation cephalosporins (OR = 3.00, p = .04) showed any association. The odds ratio for third-generation cephalosporins in the absence of clindamycin was 3.50 (p = .09). Data were collected by physicians who were not blinded.

This study found that the clindamycin and third-generation cephalosporins were risk factors for C difficile-associated diarrhea after controlling for horizontal transmission. First-generation cephalosporins were not risk factors (OR= 0.86), while sample size considerations prevented firm conclusions about second-generation cephalosporins (OR = 1.67, p = .23). Many of the previously alleged risk factors might be explained by the horizontal transmission of an infectious disease; for instance, this seems a better explanation for an outbreak on a surgery ward than does surgery itself. (Infect Control Hosp Epidemiol. 1991;12:96-100.)