An outbreak of group A streptococcal infection in a maternity unit

Hospital-acquired invasive group a streptococcal infections in Ontario, Canada, 1992-2000

BACKGROUND

A significant proportion of invasive group A streptococcal infections are hospital acquired. No large, prospective studies have characterized this subgroup of cases and evaluated the risk of transmission in hospitals.

METHODS

We conducted prospective, population-based surveillance of invasive group A streptococcal infections in Ontario, Canada, from 1992 to 2000. Epidemiologic and microbiologic investigations were conducted to identify cross-transmission.

RESULTS

We identified 291 hospital-acquired cases (12.4%) among 2351 cases of invasive group A streptococcal disease. Hospital-acquired invasive group A streptococcal infections are heterogeneous, including surgical site (96 cases), postpartum (86 cases), and nonsurgical, nonobstetrical infections (109 cases). Surgical site infections affected 1 of 100,000 surgical procedures and involved all organ systems. Postpartum infections occurred at a rate of 0.7 cases per 10,000 live births and exhibited an excellent prognosis. Nonsurgical, nonobstetrical infections encompassed a broad range of infectious syndromes (case-fatality rate, 37%). Nine percent of cases were associated with in-hospital transmission. Transmission occurred from 3 of 142 patients with community-acquired cases of necrotizing fasciitis requiring intensive care unit (ICU) admission, compared with 1 of 367 patients with community-acquired cases without necrotizing fasciitis admitted to the ICU and 1 of 1551 patients with other cases (P<.001). Fifteen outbreaks were identified; 9 (60%) involved only 2 cases. Hospital staff were infected in 1 of 15 outbreaks, but colonized staff were identified in 6 (60%) of 10 investigations in which staff were screened.

CONCLUSIONS

Presentation of hospital-associated invasive group A streptococcal infections is diverse. Cross-transmission is common; illness occurs in patients but rarely in staff. Isolation of new cases of necrotizing fasciitis and intervention after a single nosocomial case may also prevent transmission.

Spread of Klebsiella in a neonatal ward

The colonization of infants with Klebsiella pneumoniae was prospectively studied. Samples were taken from nose, throat, umbilicus and rectum on the day of arrival and thereafter once a week. Phage typing was performed the first time K. pneumoniae was found at any of these sites. Settle plates were exposed in the incubators and in the patient rooms 5 h/day. The study lasted for 32 weeks. The first 15 weeks was a control period with no information to the staff, the following 4 weeks was a period of intervention and education and the last 13 weeks was a second control period. In all, 603 infants were investigated. The number of infants nursed per week and severity of their disease was comparable in the 3 periods. The colonization rates were 65, 34 and 58%, respectively. The acquisition of new strains was 1.4 per infant in the first and last periods, but only 0.4 in the period of intervention. Thus, colonization rates decreased only during the period of continuous education in hygiene.