To investigate an outbreak of Serratia marcescens in a maternity hospital (November 1994 to May 1995).

Retrospective analysis of epidemiological data and prospective study of systematic bacteriological samples from patients and environment, with genotyping of strains by arbitrarily primed polymerase chain reaction.

A private maternity hospital, Saint-Etienne, France.

In the neonatal unit, 1 newborn developed a bacteremia, and 36 were colonized in stools with S marcescens. As the colonization of some newborns was shown to occur only a few hours after delivery, the inquiry was extended to other maternity wards, where 8 babies and 4 mothers were found to be colonized. Environmental sampling led to the isolation of S marcescens from a bottle of enteral feed additive in the neonatal unit and from the transducers of two internal tocographs in the delivery rooms. The genotyping of 27 strains showed two different profiles: a major epidemic profile shared by 22 strains (18 from babies of the neonatal unit, 2 from babies of other units, and 2 from breast milk) and another profile shared by 5 strains (2 from transducers of internal tocographs, 2 from babies, and 1 from a mother). The strain isolated from lipid enteral feeding was not available for typing. Although this source of contamination was removed soon from the neonatal unit, the outbreak stopped only when infection control measures were reinforced in the delivery rooms, including the nonreuse of internal tocographs.

In delivery rooms, the quality of hygiene needs to be as high as in surgery rooms to prevent nosocomial colonization or infection of neonates at birth.

To describe the epidemiology of measles in medical settings and to evaluate the implementation and effectiveness of the 1989 Advisory Committee on Immunization Practices (ACIP) guidelines for measles immunization in healthcare workers (HCWs).

Confirmed cases of measles reported in Clark County, Washington, from March 14 to June 2,1996, were analyzed for characteristics of cases occurring in medical settings. A questionnaire was used to assess employee immunization (95% response rate).

Reported measles cases and HCWs at community hospitals, primary-care medical facilities, a health-maintenance organization, and a multispecialty group practice.

Of 31 cases of measles, 8 (26%) occurred in HCWs, and 5 (16%) occurred in patients or visitors to medical facilities. Cases of measles occurred in HCWs who were not required to have proof of measles immunity as defined by the 1989 ACIP guidelines. The relative risk of measles in HCWs compared to Clark County adults was 18.6 (95% confidence interval, 7.4-45.8; P<.001).

A survey of medical facilities revealed that 47% had an employee measles immunization policy; only 21% met ACIP recommendations and enforced their policies.

HCWs were at higher risk of measles than the adult population. Transmission of measles in medical settings was related to both deficiencies in, and lack of implementation of, the ACIP guidelines.

To describe the molecular epidemiology of Legionella pneumophila infections in the University of Iowa Hospitals and Clinics (UIHC).

Molecular epidemiological study using pulsed-field gel electrophoresis (PFGE).

A large university teaching hospital.

All surviving isolates obtained from culture-proven nosocomial L pneumophila infections and all surviving isolates obtained from the University of Iowa Hospital and Clinics' water supply between 1981 and 1993.

Thirty-three isolates from culture-proven nosocomial cases of L pneumophila pneumonia were available for typing. PFGE of genomic DNA from the clinical isolates identified six different strains. However, only strain C (16 cases) and strain D (13 cases) caused more than 1 case. Strain C caused clusters of nosocomial infection in 1981, 1986, and 1993 and also caused 4 sporadic cases. Strain D caused a cluster in 1987 and 1988 plus 4 sporadic cases. Of the six strains causing clinical infections, only strains C and D were identified in water samples. PFGE identified three strains in the water supply, of which strains C and D caused clinical disease and also persisted in the water supply during most of the study period.

Specific strains of L pneumophila can colonize hospital water supplies and cause nosocomial infections over long periods of time.

The overall aim of this study was to investigate the survival and possible growth of Mycobacterium tuberculosis simulant bacteria on respirator filters.

Mycobacterium smegmatis was used as a biochemical simulant for M tuberculosis. Bacterial survival was tested on National Institute for Occupational Safety and Health-certified N95 respirators from three manufacturers. The first experiments simulated one-time respirator use and subsequent storage for 1 to 9 days under ideal conditions for the growth of mycobacteria: 37°C and 85% relative humidity. The bacteria were loaded on the respirator filters under three different nutritional conditions: in the absence of nutrients; in the presence of human saliva (simulating conditions when the respirator is worn); and in the presence of nutrient broth (for ideal growth potential). The subsequent experiments simulated respirator wear for 2 hours under medium workload conditions at a breathing rate of 56 L/min.

It was found that M smegmatis did not grow on the tested respirators, even when the respirators were stored at temperature, humidity, and nutrition conditions most favorable for microbial growth. However, these bacteria could survive on respirators for up to 3 days during storage. The culturability of M smegmatis was not affected by airflow that simulated the breathing rate associated with medium work-load conditions for 2 hours.

This study shows that M tuberculosis surrogate bacteria collected on a respirator are not able to grow and are able to survive only in ideal (ie, not clinically relevant) conditions. Based on these experiments, we conclude that M tuberculosis is unlikely ever to become an infectious problem in the air again, once it is removed by a respirator.