Prevalence of group B streptococcus colonization in pregnant women and the correspondence of its virulence genes with adverse pregnancy outcome

Document Type : Original Article


1 Department of Medical laboratories, Directorate Babylon of Health, Iraq

2 Medical Microbiology/ College of medicine, Al-Nahrain University, Iraq

3 Department of Medical laboratories, Medical City, Burns Specialist Hospital, Ministry of Health, Iraq


Background and rationale:  Group B Streptococcus (GBS) is a Gram-positive, non-motile, encapsulated bacterium classified under Lancefield group B antigen. Predominantly found in the gastrointestinal and genitourinary tracts. GBS is a leading cause of invasive bacterial diseases in neonates, including neonatal sepsis, meningitis, septicemia, and pneumonia. Aim: To study the vaginal colonization rate of Streptococcus agalactiae and virulence genes in pregnant women with adverse pregnancy outcome.  Methods: A cross-sectional study was designed included 200 pregnant women at 34–37 weeks of gestation. A total of two hundred vaginal swabs were taken from all pregnant women enrolled in this project by the gynecologist. GBS isolated bacteria was evaluated by means of using classical microbiological approaches. After DNA extraction, the isolated GBS strains were screened for the presence of cfb and scpB gene by polymerase chain reaction. Results: Thirty-six (18%) of 200 pregnant women enrolled in this project were positive for group B Streptococcus by culture methods. The majority were 18–36 years old, 20 (20.6%) had a history of abortion, and 10 (9.9%) had rupture membranes of >18 hours. The particular PCR primer detected scpB and cfb genes. The scpB gene was discovered in 17 (47%), whereas the cfb gene was detected in 31 (86%). Conclusion: There is no statistical significance between repeated abortions with the presence of scpB and cfb genes as a virulence factor in GBS while there is statistical significance between the presence of these virulence genes and rupture membranes.


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