[Prevention of perinatal infection caused by group B beta-hemolytic streptococcus].

Streptococcus agalactiae strains or group B streptococci (GBS) are the leading cause of bacterial pneumoniae, sepsis and meningitis in neonates. GBS is also a major cause of bacteriemia in pregnant women. Colonization of the human rectovaginal tract with GBS is a risk factor associated with chorioamnionitis and transmission of the infection to the infant. Neonatal exposure to high concentrations of GBS, mainly during vaginal delivery, leads to colonisation of the lung airways and subsequent onset of severe diseases like pneumonia, sepsis and menigitis. GBS is present in the genitourinary tract of 10% to 40% of pregnant women, about 50% of the newborns of these mothers will be colonised during delivery and of these neonates, 1% to 2% present a severe invasive disease. The early-onset disease, appear in the neonates within 7 days of life and more than 90% occur within the first day of life. Fatal infection is associated commonly with fulminat and overwhelming early-onset disease. Maternal-intrapartum chemoprophylaxis is able to prevent the transmission of GBS to the newborn and to reduce the frequency and the severity of early onset disease. In many countries, in particular in US, several recommendations have been proposed to prevent the perinatal GBS infection. In this paper some recommendations to prevent GBS disease of the newborn, performed in collaboration with Italian Society of Perinatal Medicine, are presented. The most important problem in the prevention programme is the identification of the cases to treat, since it is not possible to give antibiotics to all the women. We combine two strategies for the identification of the women to be treated, one risk based and the other screening based. Intra-partum administration of ampicillin or penicillin is recommended for the women with one or more risk-factors (labour < 37 weeks of gestation, duration of ruptured membranes > = 18 hours, intrapartum temperature > = 38 degrees C, previous infant with invasive GBS disease, diabetes) and for women with collect vaginal and rectal swab for GBS culture at 36-38 weeks' gestation, positive for GBS. No treatment is required for the babies of women intrapartum treated or with negative culture performed near term. Treatment with ampicillin is necessary, only in the new-borns of women with incomplete or unknown results or not done cultures and in those born from mothers with positive cultures, but not intrapartum treated. Collection of swabs for GBS is recommended before antibiotic administration. If the culture is negative, we suggest to stop the antibiotic therapy, otherwise the treatment must be continuated for 5-7 days. In conclusion, a written protocol for prevention of GBS infection in new-born must be adopted in every delivery centre and one possible protocol is proposed in this paper.