[Antimicrobial drug susceptibility of 365 Streptococcus agalactiae strains isolated in 1999-2006]

In vitro resistance to antimicrobials and its dynamics were evaluated in 365 strains of group B. Streptococcus agalactiae (SGB) isolated in 1999-2006 from female patients in an obstetrics and gynecology clinic of Moscow. Susceptibility to ampicillin, cefazolin, clindamycin, erythromycin, ofloxacin, penicillin, tetracycline and vancomycin was tested with the automatic Vitek 1 system and disk diffusion and double disk method according to CLSI/NCCLS. All the isolates were susceptible to ampicillin, cefazolin, penicillin and vancomycin. Tetracycline, erythromycin, clindamycin and ofloxacin resistance was detected in 78.1, 20.8, 9.0 and 1.1% of the isolates respectively. Three out of 19 strains resistant to erythromycin and susceptible to clindamycin showed inducible resistance to clindamycin in the D test with the Vitek 1 system. No significant differences in the resistance of the SGB strains isolated from diverse clinical materials were observed. Analysis of the resistance of the strains isolated in 1999-2006 demonstrated that resistance to erythromycin increased from 15.6% in 1999-2002 to 24.1% in 2003-2006 (p < 0.05). The tetracycline resistance within the same period lowered from 87.9 to 71.9% (p < 0.01). Therefore, penicillin remained to be the drug of choice for the prophylaxis and treatment of diseases due to SGB. The high of the SGB resistance to erythromycin and clindamycin suggested the use of non-beta-lactam antibiotics by the results of the in vitro susceptibility tests alone. The D-test should be routine in determination of the SGB susceptibility to clindamycin in clinical diagnostic laboratories.