Primary prevention
Group B streptococci (GBS) are a leading cause of neonatal sepsis, and are acquired before birth from bacteria colonising the maternal vagina. Studies have shown that active screening for colonisation, together with intrapartum antibiotics given to carriers and at-risk groups, has reduced the incidence of early-onset GBS infection and is the recommended means of prevention in the US.[6][56][57] However, the effectiveness of screening has been disputed in a systematic review. The review concluded that although intrapartum antibiotics in GBS-colonised mothers appear to reduce early-onset GBS disease, this may be the result of bias in study design and execution. In addition, the review noted that intrapartum antibiotic prophylaxis did not significantly reduce the incidence of all-cause mortality, mortality from GBS infection, or from infections caused by bacteria other than GBS.[58] The American College of Obstetricians and Gynecologists recommends a screening strategy for prevention of early-onset GBS infection.[6] Local guidelines should also be referred to.
In clinical practice, patients with indications for intrapartum antibiotic prophylaxis should receive either benzylpenicillin or ampicillin until delivery. The recommended antibiotics for patients with penicillin allergy depend on the risk of anaphylaxis, angio-oedema, respiratory distress, or urticaria following administration of penicillin or a cephalosporin. Patients with penicillin allergies and a low risk for anaphylaxis (based on clinical history) should receive cefazolin until delivery. Prophylaxis for those at high risk of anaphylaxis depends on antimicrobial susceptibility tests. If the isolate shows no inducible resistance and is sensitive to it, clindamycin should be administered until delivery, while if resistance or inducible resistance is present or sensitivities are unknown, vancomycin should be administered until delivery. For the purposes of determining neonatal management, maternal antibiotic prophylaxis is only deemed adequate if penicillin, ampicillin, or cefazolin has been continued for at least 4 hours prior to delivery. Maternal prophylaxis with clindamycin or vancomycin is not considered adequate with respect to the neonate, regardless of the duration of administration.[6]
Rectal and vaginal swabs should be obtained immediately for GBS culture, and GBS prophylaxis commenced, if signs or symptoms of premature labour (gestation <37 weeks, 0 days) develop. If true labour is entered, prophylaxis should be continued until delivery, unless negative culture results from samples taken within the previous 5 weeks are available. If delivery does not occur at this time, these culture results can be used to inform GBS status at the onset of true labour. Cultures must be repeated at 36 to 37 weeks' gestation if delivery has not yet taken place.[6]
In the event of premature rupture of membranes (PROM), GBS cultures should be obtained and prophylaxis commenced. If labour is not entered, prophylactic antibiotics should be continued for 48 hours and further antibiotics given at the onset of true labour if culture results are positive.[6]
In non-pregnant adults, infection can be prevented by attention to predisposing factors (e.g., skin care, care of urinary or central venous catheters, handwashing) and appropriate management and modulation of risk factors (e.g., diabetes, immunosuppression).[14][59]
There are currently no primary prevention measures for late-onset neonatal infection, or infection in infants, children, or pregnant women. In 2015, however, the World Health Organization identified the development of GBS vaccines as a global priority, and has since published a report describing the public health rationale for a maternal immunisation programme. Maternal vaccine candidates remain in phase 2 clinical trials.[60]
Although vaginal chlorhexidine results in a statistically significant reduction in colonisation of neonates, studies did not show a reduction in other outcomes. There is therefore no evidence to support use of vaginal chlorhexidine as a means of preventing early-onset GBS disease.[61][62][63]
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Indications for intrapartum antibiotics:[6][56][64]
Previous infant with GBS disease
GBS colonisation, bacteriuria, or infection during current pregnancy
GBS colonisation, bacteriuria, or infection in a previous pregnancy (not necessary if screening culture or polymerase chain reaction test performed between 35 and 37 weeks’ gestation [36 and 37 weeks’ gestation in the US] or 3 to 5 weeks before the anticipated delivery date if current pregnancy is negative)
Delivery at <37 weeks' gestation (not necessary if screening culture result taken within previous 5 weeks is known to be negative)
Unknown GBS status and intrapartum temperature ≥38°C (100.4°F) OR premature rupture of membranes ≥18 hours
Antibiotics clinically indicated (e.g., urinary tract infection or chorioamnionitis).
Intrapartum antibiotics are not recommended for women having a preterm planned caesarean section with intact membranes.[6][56]
Secondary prevention
Women who have babies with GBS infection should be advised to have antibiotic prophylaxis during future pregnancies.
In order to diagnose early-onset GBS infection, neonates should be managed according to local guidelines.[6] Any neonate with signs of sepsis should receive empirical antibiotics pending investigation results (blood culture, full blood count (FBC) with white cell differential and platelet count, chest x-ray if focal respiratory signs are present, and lumbar puncture if the baby is stable enough). The antibiotic regimen should cover GBS and any other potential infecting organisms.
Neonates born to mothers with chorioamnionitis, but who appear well, should undergo limited clinical evaluation (blood culture, and FBC with white cell differential and platelet count) and receive prophylactic antibiotics pending culture results. Confirmation of the diagnosis of chorioaminionitis is required to inform appropriate further management of the neonate. Those without signs of sepsis born to mothers requiring GBS prophylaxis should be observed for at least 48 hours. If the mother has received adequate GBS prophylaxis (penicillin, ampicillin, or cefazolin continued for at least 4 hours prior to delivery), the neonate can be discharged after 24 hours if medical attention is easily accessible and information for home observation is given. If adequate GBS prophylaxis has not been received by the mother and the neonate was born before 37 weeks' gestation or PROM lasting >18 hours occurred, the neonate should undergo limited clinical evaluation and be observed for at least 36-48 hours.[65]
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