1984 Volume 58 Issue 11 Pages 1206-1212
A total of 245 strains of Campylobacter jejuni including 111 from human diarrheal cases, 29 from cattle, 46 from poultry and 59 from wild birds, as well as 72 strains of Campylobacter coli, including 18 from human and 54 from swine were examined for their susceptibility in vitro to 9 antimicrobial agents, ampicillin (ABPC), erythromycin (EM), chloramphenicol (CP), tetracycline (TC), amikacin (AMK), gentamicin (GM), kanamycin (KM) cephaloridine (CER) and nalidixic acid (NA).
Susceptibility was tested by determining minimal inhibitory concentrations (MICs) of these agents according to an agar dilution method using Mueller-Hinton agar plates which contain 5% defibrinated horse blood. Growth of the test strains was observed after incubation of the inoculated plates at 37C for 48 hours under microaerophilic condition.
AMK, EM and GM were the most active agents, inhibiting growth of all the human strains and more than 90% of the animal strains of C. jejuni at a concentration of 3.12μg/ml or less. ABPC, CP, and KM were also active, and their MICs for almost all the strains of C. jejuni ranged from 0.2 to 12.5μg/ml. All the strains of C. jejuni were inhibited by NA at 25μg/ml or less. CER showed only moderate to poor activity, and its MICs were distributed between≥100 and 3.12μg/ml. The susceptibility to TC was variable, and MICs gave a bimodal distribution. Strains resistant to this drug, which were inhibited at a concentration of 12.5μg/ml or more, were 69% in human strains, 55% in cattle strains, 22% in poultry strains and 10% in wild bird strains.
The susceptibility pattern of C. coli against these agents were essentially same as that of C. jejuni. In the strains isolated from swine, however, appearance of the strains highly resistant to EM and KM were more common, representing 44% and 59%, respectively. Frequency appearance of TC-resistant strains was 33% in human strains, and 19% in swine strains.
The strains resistant to multiple drugs were observed both in C. jejuni and C. coli.
