Colonization of pregnant women with group B streptococcus: current view at the problem

Abstract

The relevance of the problem of group B streptococcus (GBS) in obstetric practice casts no doubt. Attracting the close attention of leading experts, introducing new solutions and based on practical experience gained, it is still not possible to prevent all cases of neonatal infections associated with GBS. The review article demonstrates the current view of the problem. According to the literature, African-American race in combination with sexually transmitted infections are predisposing risk factors for GBS colonization. A direct relationship between obesity and the percentage of GBS carriers was revealed. GBS-colonized primigravidas have a 50 % increased chance of detecting the pathogen in subsequent pregnancies. Absolute factors for massive GBS colonization of the birth tract include GBS-associated asymptomatic bacteriuria and a history of GBS-colonized children. It is assumed that such virulence factors as hemolytic pigment and hyaluronidase contribute to the GBS pathogenic potential. The protective function in the immune system is performed by Kaschenko–Gofbauer cells, but their role is ambiguous. Early neonatal GBS infection realized in 90 % of newborns that manifested by sepsis, pneumonia and purulent meningitis. Implemented measures to prevent early neonatal GBS infection have a number of disadvantages. False-negative results of culture screening for GBS antigen at gestational age of 35–37 weeks increase a risk of vertical transmission, whereas false-positive results underlie a reason for prescribing irrational intranatal antibiotic prophylaxis. Moreover, antenatal GBS microbiological screening and antibiotic prophylaxis at birth do not prevent the risks of late-onset neonatal GBS infection.