Antimicrobial resistance of Escherichia coli isolated from piglets in South Eastern Australian piggeries. (#102)
The Australian pig industry commonly uses antimicrobials for prevention of diarrhoeal diseases in neonatal and weaner piglets caused by Escherichia coli. E. coli is ubiquitous in both humans and animals. Surveillance of E. coli resistance from both healthy and diseased piglets is necessary to anticipate any potential threat to both animal and public health. The aim of this study was to assess resistance to antimicrobials used in human medicine in E. coli isolated from healthy and clinically sick piglets. A snapshot survey of 22 commercial piggeries located in South Eastern Australia: New South Wales n=9; Victoria n=10; and South Australia n=3 was conducted from September 2013 to May 2014. Faecal samples were collected from each herd (10 from pre-weaned and 40 from post-weaned piglets). Each sample was categorised according to a simple faecal consistency score (1 = firm and shaped, 2 = soft and shaped, 3 = loose, 4 = watery) and according to detection of β-haemolytic E. coli. A total of 325 E. coli isolates were tested for resistance to 27 antimicrobials using the BD Phoenix Automated Microbiology System (BD Diagnostics). The highest prevalence of resistance was to tetracycline (72%), with moderate prevalence of resistance to trimethoprim-sulfamethoxazole (45%) and chloramphenicol (37%). Resistance to cefazolin (8%), cefoxitin (5%) and ceftriaxone (3%) was less common but continued monitoring for emerging resistance to these antimicrobials is essential because of their status in human therapeutics. E. coli from Australian piglets appear to show comparable or slightly lower antibiotic resistance levels than those in European pig producing countries, however several multi-drug resistant isolates (including drugs important for human health) were observed in this study and require further investigation.