Antibiotic susceptibility of canine Bordetella bronchiseptica isolates

The antimicrobial sensitivities of 78 recent (1995-1998) canine isolates of Bordetella bronchiseptica from 13 separate sources were determined. Minimu m inhibitory concentrations were assessed using the E-test method or by aga r dilution. All 78 isolates were sensitive to tetracycline, doxycycline, en rofloxacin, and amoxycillin/clavulanic acid; the majority were sensitive to ampicillin (63/78; 81%), trimethoprim (57/78; 73%), and sulphadiazine (63/ 78; 81%). Plasmids were detected in 14 out of the 24 isolates tested. There was no correlation between the presence of plasmids and antibiotic resista nce, but there was some correlation between the presence of plasmids and th e origin of the isolates. Three sizes of plasmid were found: 20, 14, and 5. 5 kb, Eight of the isolates contained all three plasmids, the remainder one or two. Thirteen isolates demonstrated beta-haemolysis, of which six produ ced a soluble haemolysin. Except for one isolate, haemolysin production cor related with plasmid carriage, Pulsed-field gel electrophoresis showed that all except one isolate could be grouped in the same genotype. Within this genotype isolates could be divided into three subtypes, generally correspon ding to their place of origin. (C) 2000 Elsevier Science B.V. All rights re served.