Antibiotic resistance patterns of group B streptococci in late third-trimester rectovaginal cultures.
OBJECTIVE
Our purpose was to determine the antibiotic sensitivity patterns of rectovaginal group B streptococcal isolates obtained from a heterogeneous obstetric population in the late third trimester.


METHODS
We performed a prospective observational study of rectovaginal group B streptococcal isolates obtained in the late third trimester during routine screening over a 12-month period. All cultures were prepared in a selective broth medium for 18 to 24 hours before plating onto sheep blood agar. Susceptibility testing of all isolates was performed for ampicillin, cefazolin, clindamycin, erythromycin, penicillin G, and vancomycin with the E-test method.


RESULTS
A total of 2111 consecutive rectovaginal cultures were performed in which group B streptococci were isolated from 574 (27.2%) different patients. The "antibiogram" of the susceptible percentage is as follows: vancomycin, 100%; ampicillin, 98.2%; penicillin G, 98.2%; cefazolin, 98.1%; clindamycin, 92%; erythromycin, 81%. Ten isolates (1.8%) demonstrated intermediate susceptibility to both ampicillin and penicillin G.


CONCLUSIONS
Routine susceptibility testing of group B streptococcal isolates collected during pregnancy should be considered because of the emergence of antibiotic resistance among group B streptococcal strains.
Bland
M L
ML
Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston 29425, USA.
Vermillion
S T
ST
Soper
D E
DE
Austin
M
M
D000328:Adult; D004352:Drug Resistance, Microbial; D005260:Female; D006801:Humans; D008826:Microbial Sensitivity Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000382:microbiology; D011263:Pregnancy Trimester, Third; D011446:Prospective Studies; D012007:Rectum / Q000382:microbiology*; D013292:Streptococcus agalactiae / Q000502:physiology*; D014621:Vagina / Q000382:microbiology*