Prevalence of <i>Streptococcus agalactiae</i> colonization in a sample of pregnant and non pregnant women in Porto Alegre, Rio Grande do Sul state, Brazil

Abstract

AIMS: To determine the prevalence of Streptococcus agalactiae in vaginal and rectal samples of pregnant and non-pregnant women, analyzed in a private laboratory in Porto Alegre, Rio Grande do Sul state, Brazil, from January 2011 to June 2012. METHODS: The study included all culture results of vaginal and anorectal samples collected from pregnant and non-pregnant women, aged 18 years or more, from January 2011 to June 2012, in a private laboratory in the city of Porto Alegre. The samples were plated on blood agar and chromogenic specific for S. agalactiae, being analyzed in the CAMP test for samples with positive bacterial growth. Statistical analysis was performed using the chi-square and p values less than 0.05 were considered significant. RESULTS: We analyzed 1146 samples, being 963 of 2011 and 183 of the first half of 2012, of which 105 were from pregnant and 1041 and were from non-pregnant women. Among the 1146 women surveyed, 83 (7.2% - 95% confidence interval: 5.8%-8.8%) were colonized with S. agalactiae. There was a higher frequency of positive samples in the group of pregnant women (15.2%) than in the group of non-pregnant women (6.4%) (p equals 0.002). This difference is mainly due to the results of the year 2012, when the pregnant group had 23.1% of positive samples, while the non-pregnant group had 6.3% (p equals 0.004). CONCLUSIONS: The high incidence of colonization by S. agalactiae among the pregnant women screened emphasizes the importance of detecting this colonization in late pregnancy for the effective prevention of neonatal streptococcal disease.