[Epidemiology of beta-hemolytic streptococcus group B colonization in perinatology. Methodology considerations and personal data]. / Epidemiologia della colonizzazione da streptococco beta-emolitico gruppo B (GBS) in perinatologia. Considerazioni metodologiche e dati personali.

GBS have attracted increasing attention in recent years as a major cause of serious neonatal sepsis. The maternal genital tract is the principal source of organism for babies with the most serious early onset form of disease. Reported rates of GBS carriage in the genital and anorectal tract of pregnant women vary widely: much of the variations is undoubtedly associated with differences in laboratory technique, sampling site and number of samples taken. The key bacteriological factor is the use of enrichment culture technique. We have studied GBS colonization in 274 pregnant women during labor and in their newborns (275). Carriage was documented in 25.91% women by vaginal (low portion) and anorectal swabs, and in 6.14% newborns by auricolar, pharyngeal and rectal swabs taken at birth and before leaving nursery. The higher rectal colonization rate in pregnant women suggests that the gastrointestinal tract is the primary site of GBS carriage. Colonized newborns have no obstetrics risk factors, except for maternal GBS carriage. Our data confirms that limiting antimicrobial intrapartum prophylaxis to premature infants leaves term infants (who account for 60% of the fetal cases of early onset disease) unprotected, unless membrane rupture is prolonged. Prevention of early onset infections among low-risk term infants will require additional investigations.