RESUMEN
OBJECTIVE: To estimate the prevalence and analyze the factors associated with group B Streptococcus (GBS) colonization in pregnant women of Los Altos, Chiapas, Mexico. MATERIAL AND METHODS: Between February and September 1999, a cross-sectional study was conducted among 910 women who sought delivery care at three public hospitals of San Cristobal de Las Casas, Chiapas. Vaginal and perianal samples were taken for GBS detection by bacteriological culture. Identification of groups and serotypes was performed using latex agglutination. The analysis of factors associated with colonization was done using chi-squared tests and log-linear modeling. RESULTS: GBS colonization was found in 8.6% (95% CI 6.8-10.5) of study subjects. Women with the greatest likelihood of colonization were those with > or = 5 pregnancies, residents of counties with high levels of poverty, working outside the home, and living in homes in which the head of household worked in agriculture (26.8%, OR = 7.25, 95% CI 1.83-28.67). CONCLUSIONS: In the study area, it is necessary that actions aiming to prevent and control infections by GBS be directed principally at those groups of women with the highest probability of colonization, in order to diminish the perinatal transmission of GBS.