[Streptococcus B screening with GBS medium in obstetrics].

Pregnant women and newborn infants were screened for group B streptococcal (GBS) colonization by obtaining paired swabs from the cervix and urethra for the former group and from the ear, nose, umbilical cord, gastric juice and membranes for the latter. One swab was cultured on blood agar; the other was inoculated into serum-starch broth (GBS medium), which allows identification of GBS by production of a characteristic orange-colored pigment. From the 2105 paired swabs obtained, a total of 158 were GBS positive by either method; of these, 154 (97.5%) were recovered by the GBS medium and 89 (56.3%) by blood agar plate. No false positive color reactions were observed with GBS medium. 75% of the positive GBS media could be read within 24 h of incubation. The use of GBS medium proved to be an easy and reliable method for screening of maternal and neonatal GBS colonization.