Epidemiological investigation of beta-lactam antibiotic induced vancomycin-resistant MRSA from clinical isolated MRSA--comparison of detection rate of BIVR with or without CZX

Recently, beta-lactam antibiotic induced vancomycin-resistant MRSA (BIVR) has been reported increasingly in Japan. Between 1998 and 2002, we tried to detect BIVR from 500 strains of MRSA in a cancer hospital. And the difference of the detection rate under condition of pre-culture with or without ceftizoxime was compared. The detection rate of BIVR under condition of pre-culture with 1.0 mg/L of ceftizoxime was 20.4% (102/500), and without ceftizoxime was 9% (45/500). That of preculture with 1.0 mg/L of ceftizoxime was higher than those without ceftizoxime with the significant difference. (p < 0.001; McNemar-t examination). In comparing each department, the detection rate of BIVR from Chemotherapy, Head & Neck, and Urology department was 33.3%, 27.0%, and 20.0%, respectively. These results mean that addition of beta-lactam as ceftizoxime in pre-culture induces the ability of resistance to vancomycin for MRSA having a capacity as BIVR.