Antimicrobial susceptibility testing of Brachyspira intermedia and Brachyspira pilosicoli isolates from Australian chickens

Hampson, D.J.ORCID: 0000-0002-7729-0427, Stephens, C.P. and Oxberry, S.L. (2006) Antimicrobial susceptibility testing of Brachyspira intermedia and Brachyspira pilosicoli isolates from Australian chickens. Avian Pathology, 35 (1). pp. 12-16.

Abstract

Susceptibilities of predominantly Australian isolates of the pathogenic intestinal spirochaetes Brachyspira intermedia (n=25) and Brachyspira pilosicoli (n=17) from chickens were tested in agar dilution against four concentrations each of the antimicrobials tiamulin, lincomycin, tylosin, metronidazole, tetracycline and ampicillin. Based on available minimum inhibitory concentration (MIC) breakpoint values for Brachyspira hyodysenteriae or other Gram-negative enteric veterinary pathogens, isolates of both species generally were susceptible to tiamulin, lincomycin, metronidazole and tetracycline. Although not classed as resistant, four isolates of B. intermedia had an elevated MIC range for tiamulin (1 to 4 09mg/l), 11 isolates of B. intermedia and five of B. pilosicoli had an elevated MIC range for lincomycin (10 to 50 09mg/l), one isolate of B. pilosicoli had an elevated MIC range for tetracycline (10 to 20 09mg/l), and one isolate of B. intermedia and five of B. pilosicoli had an elevated MIC range for ampicillin (10 to 50 09mg/l). A clear lack of susceptibility to tylosin (MIC 0A> 0A4 09mg/l) was seen in 11 isolates each of B. intermedia and B. pilosicoli, and to ampicillin (MIC 0A> 0A32 09mg/l) in two isolates of B. pilosicoli. These data suggest that some resistance to common antimicrobials exists among intestinal spirochetes obtained from laying hens and supports the need of MIC data for clinical isolates before any treatment is considered.

Item Type:	Journal Article
Murdoch Affiliation:	School of Veterinary and Biomedical Sciences
Publisher:	Taylor & Francis
Copyright:	2006 Houghton Trust Ltd.
URI:	http://researchrepository.murdoch.edu.au/id/eprint/12683

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