In vitro susceptibility of group B Streptococcus strains isolated from genital tract of pregnant women

Abstract number: P1741

Bosch J., Guardià C., Juncosa T., Andreu A., Lite J., Sanfeliu I.

Objectives: Group B Streptococcus (GBS) early neonatal sepsis prevention, requires GBS detection in pregnant women genital tract, and intrapartum prophylaxis with penicillin or ampicillin administration. In women with allergy to penicillin, administration of clindamycin or erythromycin, and vancomycin in case of resistance to these antibiotics, is suggested. The aim of the study is the GBS resistance surveillance.

Methods: Between May to November 2007, in six different Microbiology laboratories of Barcelona, Spain, the in vitro susceptibility of 591 GBS strains was studied. The strains were isolated from genital tract (vaginal and/or rectal swabs) of women between 35–37 weeks of gestation. Susceptibility to clindamycin, erythromycin, telithromycin and fosfomycin was performed by disk-diffusion and/or microdilution tests. The resistance mechanisms to clindamycin, erythromycin and telithromycin were assessed by disk-diffusion method.

Results: 140 strains (236%) showed resistance to any of four antibiotics: 102 (17.2%) to clindamycin, 106 (17.9%) to erythromycin, 18 (3.0%) to telithromycin and 29 (4.9%) to fosfomycin.

86 strains presented a constitutive MLS-B phenotype (clindamycin and erythromycin resistant), 14 inducible MLS-B phenotype (erythromycin resistant and clindamycin inducible resistance), 6 M phenotype (erythromycin resistant and clindamycin susceptible) and 2, unknown mechanism (erythromycin susceptible and clindamycin resistant). Of the 18 strains with resistance to telithromycin, 13 presented a constitutive phenotype and 5 an inducible phenotype.

Increasing resistance rate to these antibiotics has been observed since the last multicentre study performed in Spain in year 2002 (with resistance rates as follows: 12.4% to erythromycin, 11.8% to clindamycin, 1.8% to telithromycin and 0.3% to fosfomycin).

Conclusion: Susceptibility surveillance is required in genital GBS strains isolated from penicillin allergic women, due to the high and increasing resistance rates to clindamycin and erythromycin. Since GBS remains quite susceptible to fosfomycin, this antibiotic could be an alternative in some cases.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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