[Streptococcus pneumoniae transmission in a nursing home: analysis of an epidemic outbreak]. / Transmisión de Streptococcus pneumoniae en una residencia de ancianos: análisis de un brote epidémico.

ABSTRACT

BACKGROUND AND OBJECTIVE: On the basis of an outbreak of pneumococcal pneumonia in a nursing home, we analyze causes and patterns of transmission and discuss preventive interventions carried out on the target population. PATIENTS AND METHOD: A retrospective cohort study was designed on 232 residents to identify risk factors associated with the outbreak. A descriptive study of those nasopharyngeal carriers of pneumococcus among nursing home workers was also carried out. RESULTS: Twenty cases of pneumococcal pneumonia were detected with 4 deaths; 13 cases were confirmed. Cases occurred on a close temporal aggregation form but they were quite disseminated spatially. Among the factors investigated, an older age was the only factor significantly associated (p = 0.02) with the risk of disease. In 4 workers, strains of Streptococcus pneumoniae were isolated from nasopharyngeal swabs; two of them corresponded to the serotype 3, as it was the strain isolated from the blood of a nursing home case. The number of new cases decreased dramatically after vaccination and/or chemoprophylaxis. CONCLUSIONS: Vaccination and chemoprophylaxis administered to nursing home residents seemed effective measures to halt the spread of this outbreak. Detection of the S. pneumoniae antigen by immunochromatographic tests in urine samples is a valuable tool for detecting an outbreak.