[Evaluation of the Granada medium used for the determination of Streptococcus agalactiae at the eighth month of pregnancy].

Granada medium (GM) was evaluated for the detection of group B streptococci (GBS) in vaginal swabs compared with the standard culture on selective blood agar (BA) and classical identification methods. From May to November 2002, samples from 325 pregnant women (34 to 37 weeks of gestation) were processed and 44 of these women (13.5%) carried GBS. Comparatively, GM was found more sensitive than the selective BA (95% versus 91%) in GBS recovery. The characteristic red-orange colonies produced by GBS are so specific that further identification is unnecessary. The technique is simple and results are available after overnight incubation, improving the time to reporting a GBS-positive result by at least 24 h. The inconvenience of anaerobic incubation of GM plates can be avoided when a cover slide is placed upon the inoculum because the same pigmentation is obtained under these aerobic conditions. This study confirms that the routine use of GM appears to be an accurate, easy and highly sensitive method of identification of GBS in pregnant women. Copyright John Libbey Eurotext 2003