Evaluating of molecular diagnostic accuracy of pregnant women colonization with Group B Streptococcus after bacterial enrichment culture

Abstract

Introduction: Pregnant women colonization with Group B Streptococcus (GBS) besides infecting the mother can increase the risk of preterm labor and transmission of bacteria to neonate during childbirth, which can cause sepsis and neonatal meningitis during the first 6 weeks of life.Therefore, this study was performed with aim to identify the colonization in pregnant women with Streptococcus agalactiae referred to two Isfahan by PCR after 4 and 24 hours of enrichment culture and comparing with phenotypic results. Methods: This descriptive study was performed on 200 pregnant women with gestational age of 35-37 weeks who had referred to Shahid Beheshti hospital in Isfahan during one year (2015) for monthly examinations. Sampling was done from the vaginal area (a third terminal) and rectum by sterile swabs separately. Collected specimens were transferred to enrichment broth medium and after 4 and 24 hours incubation, PCR method was performed. After 24 h, all specimens were evaluated using phenotypic methods. Also, sensitivity and specificity of molecular method were calculated. Data were analyzed by SPSS software (version 19), and logistic regression. PResults: Among 200 pregnant women, 22 (11%) were colonized using phenotypic and 27 (13.5%) were colonized using PCR methods after 4 and 24 hours; no difference was observed between the results. According to the results of statistical tests, the sensitivity of molecular method after the mentioned times was 100% and the specificity were 97% and 95% for vaginal and rectal specimens, respectively. Conclusion: Using PCR method after 4 hoursincubation of enrichment medium not only increase the speed of the colonization detection in pregnant women with Streptococcus agalactiae, but also provides the opportunity to perform the antibiotic susceptibility tests after bacteria growth and chose the appropriate prophylaxis or treatment if needed.

Keywords

• colonization
• molecular diagnosis
• streptococcus agalactiae