Antibiotic resistant Escherichia coli in southeastern Australian pig herds and implications for surveillance

Summary To investigate public health implications of antibiotics to control post‐weaning scours, we surveyed 22 commercial pig herds in southeastern Australia. Fifty faecal samples per herd were collected from pre‐ and post‐weaned piglets. Presumptive Escherichia coli isolates were confirmed by MALDI‐TOF MS. Isolates (n = 325) were screened for susceptibility to 19 veterinary antibiotics using MIC broth microdilution. All 325 E. coli isolates underwent further testing against 27 antibiotics used in human medicine and were screened for ETEC adhesin and enterotoxin genes (F4 (K88), F5 (K99), F6 (987P), F18, F41, STa, STb, Stx2e and LT) by multiplex PCR. Isolates identified as phenotypically resistant to third‐generation cephalosporin (3GC) and aminoglycoside antibiotics were screened by multiplex PCR/reverse line blot to detect common β‐lactam and aminoglycosides resistance genes, confirmed by sequencing. Twenty (6.1%) of the E. coli isolates were resistant to 3GC antibiotics and 24 (7.4%) to the aminoglycoside antibiotic gentamicin. Genetic analysis revealed six different extended spectrum β‐lactamase (ESBL) genes (blaCTX‐M‐1, ‐14, ‐15, ‐27, blaSHV‐12 and blaCMY‐2‐like genes), four of which have not been previously reported in Australian pigs. Critically, the prevalence of 3GC resistance was higher in non‐pathogenic (non‐ETEC) isolates and those from clinically normal (non‐diarrhoeal) samples. This highlights the importance of non‐E...
Source: Zoonoses and Public Health - Category: Infectious Diseases Authors: Tags: ORIGINAL ARTICLE Source Type: research