Drug susceptibility of Haemophilus pleuropneumoniae strains isolated from pigs.

Abstract
H. pleuropneumoniae strains isolated from pigs during 1974-1982 were serotyped and examined for their susceptibility to 21 antimicrobial drugs. Of 109 field isolates in Japan and surrounding countries (Japan: 105, Korea; 2, Taiwan; 2), 105 strains were of serovar 2, 2 were of serovar 3 and the remaining 2 were of serovar 5. The great majority of the field isolates, 107 strains, were highly susceptible to penicillins, chloramphenicol, tetracyclines, rifampicin, trimethoprim and furazolidon. These strains were also susceptible to cephalexin and colistin. Susceptibilities to aminoglycosides, macrolides, sulfamonomethoxine and nalidixic acid were not so high. The remaining 2 strains were found to be drug-resistant; strain Hpl was resistant to penicillin, tetracycline, streptomycin and sulfonamide, and strain 966 was resistant to streptomycin and sulfonamide. The former was identified as serovar 3 and the latter was serovar 5. All the 105 strains of serovar 2 were drug-sensitive, and no increase in the resistance of this organism had been observed from 1974 to 1982.