Antimicrobial Susceptibilities of recent clinical isolates of group B streptococci agalactiae from Belgium

peer reviewedBackground: : GBS cause severe infections in neonates, pregnant women and other adults. Empiric therapy is usually started before susceptibility results are available. Early neonatal diseases can be prevented with intrapartum antibiotic prophylaxis based on accurate susceptibility surveillance data. A previous Belgian study showed an increase of 3 to 10 % R to erythromycin (EM) through the 1990s. Methods: 187 GBS isolates consecutively received at the reference laboratory between 2001 to March 2003 were from 73 neonates (52 early-onset and 21 late-onset diseases), 52 adults and 62 from pregnant women’s vagina. MICs of penicillin (PG), EM, clindamycin (CM) and gentamicin (GM) were determined with Etest. PG MBCs were also determined by inactivating the drug in MIC plates using betalactamase. EM resistant (R) isolates were tested by the CM + EM double disk to determine macrolide R phenotypes. Results: All strains were susceptible (S) to PG and no tolerance was observed with MBCs falling within 2 dilutions of MICs. 19.2% of isolates were R to EM, with significantly more R isolates from adults (30.8%; p /=512 mg/L. Non typable strains were more R to GM (p