Detection of Streptococcus agalactiae colonization in pregnant women by using combined swab cultures: cross-sectional prevalence study.

Camila Marconi,Márcia Guimarães Da Silva,Lidia Raquel De Carvalho,Talita Trevizani Rocchetti,Vera Terezinha Medeiros Borges,Vera Lúcia Mores Rall

doi:10.1590/s1516-31802010000200003

Camila Marconi, Márcia Guimarães Da Silva + Show 4 more

Open Access

https://doi.org/10.1590/s1516-31802010000200003

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Abstract

Maternal Streptococcus agalactiae colonization and early-onset neonatal sepsis have aroused interest in the worldwide literature. Streptococcal neonatal disease is associated with significant morbidity and mortality in the perinatal period, especially among premature neonates. The aim of this study was to assess the prevalence of maternal streptococcal colonization by using combined swab cultures, compared with swab collection from a single site. Cross-sectional study at Faculdade de Medicina de Botucatu, Universidade Estadual Paulista. Samples were obtained from 405 patients at gestational ages of 35 to 37 weeks. Swabs from the perianal (rectal) region, vaginal introitus and upper lateral vaginal vault were cultured in Todd-Hewitt selective broth. Colonies suggestive of Streptococcus agalactiae were subjected to the catalase and CAMP (Christie, Atkins, Munch-Petersen) tests. To evaluate the positivity of combined swab cultures, Tukey's test was used for comparison of proportions. The prevalence of streptococcal colonization was 25.4%. Among the patients with positive cultures, 28.1% had this at only one collection site, 24.2% simultaneously at two sites and 47.5% at all three sites. Associating the swabs from two collection sites significantly increased streptococcal isolation, compared with a single swab (P < 0.05), except for perianal (rectal) collection. Use of combined swabs from three collection sites showed statistically higher isolation rates. In combined swab cultures collected from three collection sites, the prevalence of maternal Streptococcus agalactiae colonization was higher than in swabs collected from a single site.

Highlights

During the last few decades, maternal Streptococcus agalactiae (S. agalactiae) colonization and early-onset neonatal sepsis have undergone intense worldwide study
567 patients with a gestational age of 35 to 37 weeks were seen at the Faculdade de Medicina de Botucatu (FMB) prenatal service
Considering all the 405 women included in the study, the results from the cultures showed that the rate of maternal colonization with S. agalactiae was 25.4%

Summary

INTRODUCTION

During the last few decades, maternal Streptococcus agalactiae (S. agalactiae) colonization and early-onset neonatal sepsis have undergone intense worldwide study. Vertical transmission of S. agalactiae occurs when the membranes rupture and the neonate comes into contact with a colonized maternal birth canal during labor and delivery.[6] The Centers for Disease Control and Prevention (CDC) currently recommends that all pregnant women should be screened for S. agalactiae at a gestational age of between 35 and 37 weeks.[7] For patients with positive vaginal or rectal cultures, intravenous penicillin prophylaxis is recommended during labor. Implementation of this strategy has reduced early-onset neonatal sepsis by 70%.8. Some studies have consistently shown that combined swabs from different collection sites give up to 30% better yield than single vaginal swabs do.[12]

MATERIALS AND METHODS

RESULTS

DISCUSSION