Isolates, antimicrobial susceptibility profiles and multidrug resistance of bacteria cultured from samples collected from sheep in New Zealand (2003–2016)
Creators: name: C B Riley
name: H Pfeffer
name: C MacLachlan
name: L Wakeford
name: I R Gibson
name: J Benschop
name: K E Lawrence
Publisher: name: Taylor & Francis
Year: 2020
Subjects: subject: Microbiology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Biotechnology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: FOS: Earth and related environmental sciences
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: Science Policy
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: FOS: Health sciences
subject: 60506 Virology
subject: Computational Biology

description: AIM: To describe the common species, antimicrobial susceptibility and multidrug resistance (MDR) of bacteria cultured from samples submitted to veterinary diagnostic laboratories from sheep in New Zealand sheep between 2003 and 2016. METHODS: Bacterial culture and antimicrobial susceptibility test data from June 2003 to March 2016 for animals identified as sheep were obtained from two commercial veterinary diagnostic laboratories in New Zealand. Submission information included animal signalment, geographic origin, specimen description, the organisms cultured, and where available, antimicrobial susceptibilities of the isolates. MDR was defined as any isolate with resistance to ≥3 antimicrobial classes. RESULTS: There were 1,971 unique laboratory submissions, yielding 2,188 isolates. Of the 1,971 submissions, the most commonly represented breeds were Romney (933; 47.3%), Romney cross (264; 13.4%), and Coopworth (197; 10.0%), and there were more submissions from females (1,006; 51.0%) than males (184; 9.3%). Most submissions were from Canterbury (549; 27.9%), Southland (471; 23.9%), and Manawatu-Wanganui (272; 13.8%) regions. Other signalment data were inconsistently described. Submitted samples most commonly originated from the gastrointestinal tract (852; 43.2%), faeces (378; 12.1%), or liver (146; 7.4%). Of the 2,188 isolates, 1,771 (80.9%) were identified by species and 247 (11.4%) by genus, with the most common isolates being <i>Salmonella</i> spp. (880; 40.2%), <i>Campylobacter</i> spp. (408; 18.6%), <i>Listeria</i> spp. (140; 6.4%) and <i>Yersinia</i> spp. (113; 5.2%). Susceptibility results were available for 117/2,188 (5.3%) isolates from 51/1,971 (2.6%) submissions. No antimicrobial susceptibility data were available for <i>Salmonella</i> spp., <i>Campylobacter</i> spp., <i>Listeria</i> spp. or <i>Yersinia</i> spp. Overall for the isolates tested, susceptibility to the fluoroquinolones and tetracyclines was greatest, and MDR was found in 24/117 (20.5%) isolates. MDR was a more frequent finding for <i>Enterococcus</i> spp., <i>Bacillus</i> spp., and <i>Proteus mirabilis</i>, but was infrequent in isolates of <i>Staphylococcus aureus</i>, alpha-haemolytic streptococci, <i>Escherichia coli</i> or <i>Enterobacter</i> spp. CONCLUSIONS AND CLINICAL RELEVANCE: This is the first report on antimicrobial susceptibility and MDR for isolates from laboratory submissions from sheep in New Zealand. The low numbers of isolates submitted for antimicrobial susceptibility testing during the period studied mean that these findings provide limited insights into antimicrobial resistance in this population, and highlight the need to address significant gaps in our understanding of why veterinarians do not more frequently submit samples from sheep for bacterial culture and susceptibility testing.