Antimicrobial susceptibility, plasmid replicon typing, phylogenetic grouping, and virulence potential of avian pathogenic and faecal <i>Escherichia coli</i> isolated from meat chickens in Australia
Creators: name: Awawdeh, L.
name: Turni, C.
name: Mollinger, J. L.
name: Henning, J.
name: Cobbold, R. N.
name: Trott, D. J.
name: Gibson, J. S.
name: Wakeham, D. L.
Publisher: name: Taylor & Francis
Year: 2022
Subjects: subject: Space Science
subject: Medicine
subject: Microbiology
subject: FOS: Biological sciences
subject: Genetics
subject: Molecular Biology
subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Ecology
subject: 69999 Biological Sciences not elsewhere classified
subject: Cancer
subject: 110309 Infectious Diseases
subject: FOS: Health sciences
subject: 60506 Virology

description: Globally, avian colibacillosis is a leading cause of morbidity and mortality in poultry, associated with economic losses and welfare problems. Here, clinical avian pathogenic <i>E. coli</i> isolates (CEC; <i>n</i> = 50) and faecal <i>E. coli</i> isolates from healthy (FEC; <i>n </i>= 187) Australian meat chickens collected between 2006 and 2014 were subjected to antimicrobial susceptibility testing, phylogenetic grouping, plasmid replicon (PR) typing, multilocus sequence typing, and virulence gene (VG) profiling. Extended-spectrum cephalosporin (ESC)- and fluoroquinolone (FQ)-resistant <i>E. coli</i> isolates underwent further genetic characterization. Significant proportions of CEC and FEC were, respectively, susceptible (13/50; 48/187) or MDR (9/50; 26/187) to 20 tested antimicrobials. Phylogenetic groups A and C, and PR types IncFIB and IncFrep were most represented. Five tested CEC-associated VGs were more prevalent in CEC (≥ 90%) than FEC (≤ 58%). Some isolates (CEC <i>n</i> = 3; FEC <i>n</i> = 7) were resistant to ESCs and/or FQs and possessed signature mutations in chromosomal FQ target genes and plasmid-mediated <i>qnrS</i>, <i>bla</i><sub>CMY-2</sub>, and <i>bla</i><sub>DHA-1</sub> genes. Sequence type 354 (<i>n</i> = 4), associated with extraintestinal infections in a broad range of hosts, was prevalent among ESC- and/or FQ-resistant FEC. This study confirmed existence of a small reservoir of ESC- and FQ-resistant <i>E. coli</i> in Australian commercial meat chickens despite absence of use in the industry of these drugs. Otherwise, diversity of VGs and PR types in both FEC and CEC populations was identified. We hypothesize that the source of ESC- and FQ-resistant <i>E. coli</i> is external to poultry production facilities. RESEARCH HIGHLIGHTSLow-level resistance to older and newer generation antimicrobial drugs detected.The most common sequence type (ST) associated with FQ resistance was ST354 (4/10).A small proportion of CEC (<i>n</i> = 3) and FEC (<i>n</i> = 7) were resistant to ESCs and/or FQs. Low-level resistance to older and newer generation antimicrobial drugs detected. The most common sequence type (ST) associated with FQ resistance was ST354 (4/10). A small proportion of CEC (<i>n</i> = 3) and FEC (<i>n</i> = 7) were resistant to ESCs and/or FQs.