Diagnostic performance of two chromogenic media for Streptococcus agalactiae screening in pregnant women.

Document Type : Original Article


1 Department of Clinical Pathology, Faculty of Medicine, Ain Shams University, Cairo, Egypt

2 El-Galaa Hospital, Cairo, Egypt.

3 Department of Medical Microbiology and Immunology, Faculty of Medicine, Ain Shams University, Cairo, Egypt.

4 Clinical pathology department, Faculty of Medicine, Ain Shams University, Cairo, Egypt.


Background: Group β Streptococcus (GBS) colonization among pregnant females is common and is regarded as a substantial cause of neonatal diseases if not treated properly. Thus, we aimed to evaluate the diagnostic performance of two chromogenic media (Granada agar and ChromID StreptoB agar) for screening of GBS in pregnant women between 35-37 weeks of gestation. In addition, we determined their susceptibility profile for guiding the antimicrobial prophylaxis for cases of GBS colonized pregnant women. Method: This study included 112 vagino-rectal swabs collected in duplicates from 112 pregnant women between 34-37 weeks of gestation. All swabs were incubated in enrichment broth for 18 hours followed by subculture on blood agar, ChromID strepto B, and Granada agar. Growth of confirmed GBS isolate was subjected to antimicrobial susceptibility testing (AST) to penicillin, vancomycin, clindamycin, erythromycin, and cefotaxime by disc diffusion method. Results: The frequency rate of GBS among Egyptian pregnant females was (25.89%). Granada agar was the most accurate among the tested media (98.21%) versus ChromID (96.4%). We observed a high resistant rate for all the tested antibiotics. Conclusion: The examined chromogenic media showed promising results and proved to have the potential to be implemented as a screening method for GBS in pregnant women. Regarding the antibiotics’ resistance pattern, our results can be an indicator that it is no longer suitable to use the antibiotics empirically without testing. As antibiotic treatment failure is likely, it became inevitable to perform AST before starting any antibiotic to identify the most appropriate treatment for colonized pregnant women.


Main Subjects