Objective: The objective of this work is to determine the carriage rate of Streptococcus b in pregnant women in the last trimester, to specify the serotypes, to assess the antibiotic sensitivity of the carried strains and to determine the support of the resistance to macrolides and aminoglycosides. Material and methods: This was a prospective study from March 1, 2015 to September 30, 2015, which included 389 of patients consulting at the Gynecology and Obstetrics Department , Nafissa Hamoud university hospital Hussein Dey Algiers, Algeria, it has been carried out according to the recommendations of the CDC. The harvested strains benefited from a study of antibiotic sensitivity, a search of resistance gene to macrolide (ermA, erm B and Mef A) and aminoglycosides aad6 and Aph3 and serotyping were detected by multiplex PCR . Results: the carriage rate found was 22.6%. All strains were sensitive to betalactamines, 50% were resistant to macrolides and 25% to aminoglycosides. A predominance of the ermb gene and the aph3 gene was found ;with predominance of the serotype Ib. Conclusion: The carriage rate of streptococcus b is highly significative represented mainly by serotype Ib , strains are sensitive to betalactamines but 50% proved resistant to macrolides, prophylactic measures must be instituted to prevent transmission.

Keywords: Carriage ,streptococcus agalactiae,résistance,gene