Antibiotic Susceptibility of Mannheimia haemolytica, Pasteurella multocida, Mycoplasma bovis and Ureaplasma diversum Isolates from Nasal Swabs of Clinically Healthy Cattle

Abstract

Nasal swabs from clinically healthy cattle for fattening were bacteriologically examined from 2004 to 2012 in Yamagata prefecture. The pathogenic bacteria described below were found in 990 out of 1,098 cattle (90.2%); Mannheimia haemolytica (Mh) was isolated from 225 heads, Pasteurella multocida (Pm) was isolated from 835 heads, Mycoplasma bovis (Mb) was isolated from 421 heads and Ureaplasma diversum (Ud) was isolated from 270 heads, respectively. Both enrofloxacin (ERFX) and florfenicol to Mh and Pm isolates, showing a minimum 50% inhibitory concentration (MIC₅₀) of ≦0.031～0.5 mg/l and a MIC₉₀ of ≦0.031～2 mg/l. Mb and Ud had high sensitivity to ERFX, showing a MIC₅₀ of 0.2～0.78 mg/l and a MIC₉₀ of 0.25～3.13 mg/l, but Mb showed remarkably low sensitivity to macrolides (MIC range; vs. TS 1～100 mg/l≦, vs. TMS 2～128 mg/l≦).