title: The effect of intrapartum clindamycin on vaginal group B streptococcus colony counts.
abstract: OBJECTIVE
  To determine the temporal relationship between intrapartum clindamycin and vaginal Group B Streptococcus (GBS) colony counts.
  
  
  METHODS
  In this prospective observational study, women with GBS-positive, clindamycin-sensitive, antenatal rectovaginal cultures, intrapartum vaginal cultures were collected just before the first clindamycin dose (T(0)) and then every 2 h for 8 h or until delivery. Colony counts were quantified using serial dilution. Results were standardized as percent of initial colony count and analyzed using sequential Friedman tests.
  
  
  RESULTS
  Twenty-one women had positive intrapartum vaginal GBS cultures at T(0). With T(0) colony counts standardized to 100%, subsequent percents-of-baseline fell rapidly and significantly by T(2) and fell further at each subsequent point, reaching 0% by T(6). For 12 women cultured for the full 8 hours, the decline in GBS was significant at p < 0.001.
  
  
  CONCLUSIONS
  Vaginal GBS colony counts fall rapidly after intrapartum clindamycin administration, similar to declines after penicillin. This represents a possible mechanism for efficacy of chemoprophylaxis.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, University of Rochester Strong Memorial Hospital, USA. kristin_knight@urmc.rochester.edu
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Knight
authors.forename: Loralei L
authors.initials: LL
authors.lastname: Thornburg
authors.forename: Anna R
authors.initials: AR
authors.lastname: McNanley
authors.forename: Dwight J
authors.initials: DJ
authors.lastname: Hardy
authors.forename: David
authors.initials: D
authors.lastname: Vicino
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Glantz
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology; D019072:Antibiotic Prophylaxis / Q000379:methods*; D002981:Clindamycin / Q000008:administration & dosage* / Q000494:pharmacology; D015169:Colony Count, Microbial; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical / Q000517:prevention & control*; D036801:Parturition / Q000502:physiology; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000188:drug therapy* / Q000382:microbiology; D013290:Streptococcal Infections / Q000188:drug therapy* / Q000382:microbiology / Q000517:prevention & control / Q000635:transmission; D013292:Streptococcus agalactiae / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification*; D014621:Vagina / Q000187:drug effects / Q000382:microbiology; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D002981:Clindamycin