Incidence of antibiotic resistance and characterization of plasmids in Campylobacter jejuni strains isolated from clinical sources in Alberta, Canada.

Antibiotic susceptibilities of 382 strains of Campylobacter jejuni isolated in Alberta, Canada, in 1980 and 1981 were determined. Although none were resistant to erythromycin or gentamicin, 5.4 and 22% of strains were resistant to ampicillin in 1980 and 1981, respectively. Tetracycline resistance was noted in 6.8% of strains in 1980 and in 8.6% in 1981. Moreover, resistance to high-level tetracycline (32-128 micrograms/mL) was always mediated by a plasmid of 45-50 kilobases. Three transmissible plasmids from the Alberta strains were compared with the prototype plasmid pMAK175 by restriction enzyme analysis and some minor differences in restriction sites were noted between pMAK175 and pUA183. The two other plasmids pUA142 and pUA143 were 4 kilobases larger than pMAK175 and contained additional restriction sites. However, in all plasmids examined, the HincII and AccI fragments where the tetracycline-resistance determinant was located were shown to be conserved.