Evaluation of the Gram stain as a screening tool for maternal carriage of group B beta-hemolytic streptococci. The Vaginal Infections and Prematurity Study Group.
To determine the usefulness of the vaginal Gram stain as a screen for maternal group B streptococcal carriage, we compared the presence of gram-positive cocci on Gram stain with a cervicovaginal culture in 7755 women at 23-26 weeks' gestation and in 1452 women at delivery. Group B streptococci were isolated from 18.4% of women at 23-26 weeks and 14.9% of women at delivery. The sensitivity, specificity, positive predictive value, and negative predictive value of the Gram stain were 28, 69, 17, and 81%, respectively, in mid-gestation and 34, 72, 18, and 86%, respectively, at delivery. The presence of gram-positive cocci on Gram stain was strongly associated with the isolation of Gardnerella vaginalis and with the presence of bacterial vaginosis. We conclude that most gram-positive cocci seen on Gram stain are probably anaerobes or micrococci and that the vaginal Gram stain is neither sensitive nor specific enough to be of use as a tool in the diagnosis of maternal group B streptococcal carriage.
National Institute of Child Health and Human Development, Bethesda, Maryland.
J C
JC
Carey
M A
MA
Klebanoff
J A
JA
Regan
D002584:Cervix Uteri / Q000382:microbiology; D005260:Female; D005840:Gentian Violet; D006801:Humans; D008403:Mass Screening / Q000379:methods*; D010619:Phenazines; D011237:Predictive Value of Tests; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis / Q000382:microbiology*; D012680:Sensitivity and Specificity; D013194:Staining and Labeling; D013290:Streptococcal Infections / Q000175:diagnosis / Q000382:microbiology*; D013292:Streptococcus agalactiae / Q000302:isolation & purification*; D014621:Vagina / Q000382:microbiology
C035863:Gram's stain; D010619:Phenazines; D005840:Gentian Violet