Relationship between pathogenicity, susceptibility to antibiotics and serotyping of 335 Tunisian strains of Streptococcus agalactiae

Abstract number: r2118

Ferjani  A., Mhalla  S., Hannechi  N., Boukadida  J.


Group B Streptococci (GBS) are an important cause of serious infections among newborns and adults out side perinatology. Interrelationship between serotypes and the pathogenicity orients toward the vaccinal prevention and the survey serotypes-sensitivity to antibiotics provides epidemiological enlightenments on the resistance to antibiotics.


Strains of GBS isolated from all specimens in a teaching hospital were collected during a period of 21 months from 01/01/04 to 30/09/05. Strains were identified according to the conventional characters in particular by a positive hippurate test and by group B specific latex agglutination (biomérieux). Serotypes were identified by serum agglutination test with type-specific antiserum (strep-B-latex-statens Serum Institute, Copenhagen, Denmark). The susceptibility to antibiotics was determined according to the CA- SFM recommendations.


335 strains of group B Streptococcus (GBS) were kept. GBS is the main Streptococcus isolated (with more of 80% of the total Streptococcus) essentially from vaginal specimens (48%) and urine samples (32%). Thirty three percent of strains were isolated from non-pregnant adults who are essentially diabetics with a median age of 57 years and a sex-ratio of 0.22. Serotypes III, V and Ia were being most common from all clinical isolate sources. All strain isolated from blood (n = 16) came from newborns. Serotype III prevailed among GBS vaginal isolates (50%). All isolates were susceptible to penicillin, and to glycopeptides. Resistance to erythromycin was found in 30%, to lincomycin in 32% and to tetracycline in 93%. Only one strain expressed a high-level resistance (RHN) to aminoglycosids. GBS isolates resistant to macrolid belong to serotypes V and III.


2/3 of GBS were isolated in perinatology and 1/3 remaining concern essentially diabetic adult with a predominance of serotype III. The main antimicrobial resistances were noted for tetracycline (veterinary use antibiotics), macrolid and chloramphenicol. Study the relationship between serotyping and pathogenicity give possibilities of prevention by vaccination.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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