In-vitro and in-vivo activities of β-lactam antibiotics on Yersinia enterocolitica

Jimenez-Valera et al. found a high MIC of ceftazidime on strain IP 383 (256 mg/L) while in our study the geometric mean of MICs was 0 multiplied by 18 mg/L, with a range of 0 multiplied by 06 and 1 multiplied by 0 mg/L, on a collection of 126 strains of Y. enterocolitica representative of the diversity of serotypes found in the world and among which 21 were of the serotype O9 like the strain IP 383 in question. The MIC of cephalothin reported by Jimenez-Valera et al. was 1024 mg/L. This is near our previous results ranging between 8 and 512 mg/L, with a geometric mean of 78 mg/L. The inoculum concentration was 2-5 x 10 super(6) cfu/mL in both techniques with a volume of 1 mL for the broth method and 1 mu L (2-5 x 10 super(3) cfu/spot) plated onto agar. Both methods give similar results.