title: Persistence of penicillin G benzathine in pregnant group B streptococcus carriers.
abstract: OBJECTIVE
  To determine if streptococcicidal levels of penicillin G benzathine can be detected in maternal serum 4 weeks after treatment with 4.8 million units.
  
  
  METHODS
  Thirty-seven pregnant women with positive group B streptococcus vaginal or urine cultures were each given 4.8 million units of penicillin G benzathine. Maternal blood samples were collected after injection and at delivery. Serum penicillin levels were measured by high-pressure liquid chromatography. Follow-up cultures were done when possible.
  
  
  RESULTS
  None of the patients had serum penicillin levels below 0.20 microgram/mL 30 days after treatment. Cord blood levels were approximately 50% lower than maternal levels. In all but three subjects, cord blood levels exceeded 0.06 microgram/mL, the minimal inhibitory concentration for group B streptococcus. The three exceptions were patients who delivered more than 100 days after treatment. Group B streptococcus cultures were negative at the time of delivery in 72% of cases. None of the patients with positive cultures were moderately or heavily colonized.
  
  
  CONCLUSIONS
  In pregnant women, penicillin G benzathine levels are high enough to inhibit the growth of group B streptococcus for more than 4 weeks after injection with 4.8 million units. Further studies are needed to evaluate whether this regimen can prevent neonatal colonization and invasive group B streptococcus disease.
authors.affiliation: Department of Obstetrics & Gynecology, Louisiana State University School of Medicine, Shreveport, USA. jweeks1@mail.sh.lsumc.edu
authors.forename: J W
authors.initials: JW
authors.lastname: Weeks
authors.forename: S R
authors.initials: SR
authors.lastname: Myers
authors.forename: L
authors.initials: L
authors.lastname: Lasher
authors.forename: J
authors.initials: J
authors.lastname: Goldsmith
authors.forename: C
authors.initials: C
authors.lastname: Watkins
authors.forename: S A
authors.initials: SA
authors.lastname: Gall
mesh_terms: D000328:Adult; D002353:Carrier State; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006801:Humans; D007231:Infant, Newborn; D010401:Penicillin G Benzathine / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use; D010406:Penicillins / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy* / Q000382:microbiology; D013290:Streptococcal Infections / Q000188:drug therapy / Q000517:prevention & control*; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000302:isolation & purification; D013997:Time Factors
chemical_list: D010406:Penicillins; D010401:Penicillin G Benzathine