الفهرس 
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Abstract
Introduction: Group B streptococcus (GBS), known as Streptococcus agalactiae , is a facultative Gram-positive coccus originally known for causing bovine mastitis. Group B streptococcus can cause neonatal sepsis, pneumonia and meningitis. GBS can also disease in pregnant women, adults with underlying chronic medical conditions. The gastrointestinal tract is the natural human reservoir for GBS and is the source of vaginal colonization. GBS carriage in pregnant women may be chronic, intermittent or transient. . Neonatal GBS disease is acquired intrapartum from mothers with vaginal colonization with GBS. Virulence factors of GBS include the polysaccharide capsule, β-hemolysin, CAMP factor and C5a peptidase.
Aim: This study aimed at detection of the importance of GBS as a causative organism of neonatal sepsis, assessment of vaginal GBS colonization in pregnant women and identification of GBS virulence factors.
Methods: Invasive GBS were isolated from neonates by blood cultures. Colonizing GBS isolates were identified by vaginal swabbing of pregnant women using Todd-Hewitt selective broth medium. Antibiotic sensitivities and serotyping by latex agglutination were done. GBS virulence factors were studied including detection of β-haemolysin production, CAMP test on blood agar plates, C5a peptidase production encoded by scpB gene and presence of GBS ST-17 clone by PCR.
Results: GBS were isolated from 11.7% of neonates and from 18.9% of vaginal swabs. Resistance patterns of isolated invasive GBS were 29.4 %, and 17.6% for erythromycin and clindamycin respectively. Among invasive and colonizing GBS isolates, serotype III was the most common. All of GBS isolates were CAMP test positive. Hemolytic GBS were 91.4% of isolates. The scpB gene was detected in 88.2% and 88.9% of invasive and colonizing GBS isolates respectively while presence of ST-17 clone was significantly associated with invasive GBS isolates.
Conclusion: GBS is one of the important causes of neonatal sepsis in Egypt. Therefore, universal maternal screening for GBS with intrapartum antibiotic prophylaxis should be considered to reduce GBS neonatal infection. Serotype III is the commonest serotype among GBS isolates. Detection of GBS ST-17 clone by PCR can be used as a parameter to measure the invasiveness of GBS isolates.