Antibiotics in obstetrics

INDICATIONS OF INTRAPARTUM ANTIBIOTIC PROPHYLAXIS

· GBS identified by screening cultures in late gestation during the current pregnancy · Invasive GBS disease in a neonate from a previous pregnancy · GBS bacteriuria detected during any trimester of the current pregnancy · Intrapartum nucleic acid amplification test (NAAT) positive for GBS

ANTIBIOTIC PROPHYLAXIS IN OBSTETRICS

WHEN DO WE START ANTIBIOTIC PROPHYLAXIS?Unknown GBS status AND any of the following: SPONTANEOUS preterm onset of labour <= 37 weeks Prolonged ROM > 18 hours Intrapartum fever >= 38 C

What antibiotics to give?

In these situations, antibiotic therapy should be started on admission to hospital for labour or rupture of membranes, ideally at least 4 hours before delivery, and continued until the neonate is delivered. Recommended intra-partum antibiotic therapy: · IV benzylpenicillin 3 g dose followed by 1.8g 4 hourly until delivery OR If penicillin hypersensitivity (excluding immediate hypersensitivity), IV cephazolin 2 g dose 8 hourly until delivery OR If immediate penicillin hypersensitivity and GBS isolate known to be susceptible to clindamycin, IV clindamycin 600 mg 8-hourly until deliveryOR If immediate penicillin hypersensitivity and GBS isolate resistant to clindamycin or results of susceptibility testing are not available, IV vancomycin

pPROM antibiotic prophylaxis

Associated with prolonged pregnancy and a reduction in maternal and neonatal infection. Antibiotic DOES NOT alter perinatal mortality or longer term outsomes

PROPHYLAXIS DEPENDS ON PRESENCE OR ABSENCE OF INFECTION

PRESENCE OF INFECTION

· IV amoxicillin 2 g 6-hourly, IV gentamicin (as per RHH Adult Gentamicin Guideline) and IV metronidazole 500 mg 12 hourlyor· If penicillin hypersensitivity (excluding immediate hypersensitivity), IV ceftriaxone 1 g IV every 24 hours and IV metronidazole 500 mg 12 hourlyor· If penicillin hypersensitivity (excluding immediate hypersensitivity), IV ceftriaxone 1 g IV every 24 hours and IV metronidazole 500 mg 12 hourlyAUGMENTIN IN CONTRAINDICATED DUE TO ITS ASSOCIATION WITH NECROTISING ENTEROCOLITIS

ABSENCE OF INFECTION

· IV amoxicillin 2g IV 6-hourly for 48 hours, followed by amoxicillin 250 mg orally 8-hourly for a total of 7 days (IV and oral) AND · Oral erythromycin 250 mg 6 hourly for 7 days (or erythromycin (ethyl succinate formulation) 400 mg 6-hourly for 7 days In patients with penicillin hypersensitivity, give erythromycin as a single drug.

POST DELIVERY

In the presence of chorioamnionitis, continue antibiotics to complete at least 5 days of therapy (de-escalating from IV therapy to oral therapy), otherwise antibiotics can cease post delivery. Oral options include: · Amoxycillin-clavulanate 875/125 once every 12 hours OR · Cephalexin 500 mg 6 hourly and metronidazole 400 mg 8 hourly

ANTIBIOTIC IN 3rd or 4th DEGREE TEAR

Single pre-operative doses of Cephazolin 2g IV and metronidazole 500 mg IV, as early as possible before repair (ideally 15 to 30 minutes) before skin incision before the repair of a third- or fourth-degree perineal tear.

The role of post-operative antibiotic therapy is unclear but therapy is recommended following anal sphincter repair because infection in this setting carries a high risk of anal incontinence and fistula formation. Use:Oral amoxycillin+clavulanate 875+125 mg 12-hourly for 7 days OR If penicillin hypersensitivity (excluding immediate hypersensitivity), oral cephalexin 500 mg 6-hourly and oral metronidazole 400 mg 12-hourly for 7 days OR If immediate penicillin hypersensitivity, oral trimethoprim+sulfamethoxazole 160+800 mg 12-hourly and oral metronidazole 400 mg 12-hourly for 7 days