In the case of newborns and infants two general types of infections can occur. Early-onset infections occur in the first week of life, with an average onset age of 20 hours. Approximately “half of these children have signs of infection at birth with a group B streptococcal infection.”(1,2) This infection is acquired during or shortly before birth, from the microorganisms colonizing the maternal genital tract. Surveillance studies have shown” that 40% of women are carriers of group B genital or rectal streptococci”(1). Approximately “50% of children born via genital way by infected mothers become colonized”(3), although only 1-2% of those colonized develop a clinically obvious infection. Prematurity and maternal risk factors are frequently encountered. (prolonged labor, obstetric complications and maternal fever). The aspect of early-onset infection is the same as other forms of neonatal sepsis. Typical signs include: respiratory distress; lethargy; hypotension. All neonates presenting an early-onset of the disease had: bacteremia, 1/3 up to 1⁄2 had pneumonia and / or respiratory distress syndrome and1/3 had meningitis. “Delayed-onset infections occur in infants aged between one week and three months, with an average age of 3-4 weeks”(1). Microorganisms can be acquired during birth – as in early-onset cases –or later, through contact with colonized mother, medical staff or other contaminated sources. “The most common manifestation of delayed-onset infection is meningitis,”(2) which in many cases is associated with type III encapsulated strain infections. Infants have: fever; lethargy; refusal to eat ; seizures; Signs of poor prognosis are: hypotension; coma; status epilepticus; neutropenia. Over 50% of survivors have some degree of “long-term neurological damage from a slight delay in the appearance of language or hear loss, to the profound mental retardation, blindness and seizures that can not be controlled”(5). A variety of late-onset infections can occur including “bacteremia without an identified source, osteomyelitis, septic arthritis and facial cellulitis associated with preauricular or submandibular adena.”(4) “Nowadays, streptococcus B represents, together with Escherichia coli B, represents the main cause of neonatal infection.”(6) B streptococcus is responsible for 40% of neonatal infections; infections caused by this germ affects 5% of newborns, 3% are early infections and 1.5% delayed infections. The prevalence of B streptococcus neonatal infections could be the consequence of: improvement of bacteriological screening techniques; use of preventive antiseption against Staphylococcus that favoured the Streptococcus development; antibiotic treatment of pneumococcal infections, that inhibits the formation of pneumococcal antibodies for the mother and, in particular during childhood; Approximately 60% of cases are caused by type III, which contrasts with the distribution of types I, I b, Ic, II and III in "colonized" women and asymptomatic infants.