Session: Poster Session: Streptocci and Enterococci
Monday, October 27, 2008: 12:00 AM
Room: Hall C
Background: GBS is a leading cause of invasive infections in neonatal and elderly patients. We aimed to clarify the capsule-type distribution and antimicrobial resistance in GBS isolates from invasive GBS infections. Methods: A total of 151 GBS isolates were obtained from 66 Japanese medical institutions between August 2006 and July 2007. In neonatal patients (n=28), GBS isolates were obtained mostly from cases with sepsis and meningitis. In adults (n=123), on the other hand, GBS isolates were obtained predominantly from patients with sepsis, infectious endocarditis, pneumonia, and arthritis. Capsule typing was performed genetically for all isolates. Susceptibility to antimicrobial agents was determined using an agar dilution method. Genes mediating macrolide and fluoloquinolone (FQ) resistance were identified by PCR and sequence. Results: The age distribution of the elderly patients ranged from the 50s to the 90s. Most of these patients had a variety of underlying diseases such as diabetes. The GBS capsule type from neonatal infants was predominantly type III (53.6%), followed by Ia (25%) and Ib (14.2%). In adults, the most prevalent type was Ib (31.7%), followed by type V (17.9%) and types II and III (12.2%). The MIC90 of β-lactam agents (AMP, AMX, CDN, CTX, and MEM) to GBS ranged from 0.063 to 0.125 μg/ml. Strains possessing erm (A) or erm (B) gene accounted for 15.0% of all strains. Remarkably, 27% of GBS showed high resistance to LVX had two amino acid substitutions of Ser-81 to Leu in the gyrA gene and Ser-79 to Phe in the parC gene. Conclusions: These data suggest that GBS, which usually originates in the intestines, is susceptible to FQ antibiotic pressure, unlike S. pyogenes.