The occurrence of CTX-M-25-producing Enterobacteriaceae in day-old broiler chicks in Japan

Area of Science:

• Veterinary Microbiology
• Antimicrobial Resistance
• Food Safety

Background:

• Antimicrobial resistance is a growing global health concern.
• Enterobacteriaceae are common bacteria found in poultry, which can carry resistance genes.
• The spread of antibiotic resistance in food-producing animals is a significant pathway for human exposure.

Purpose of the Study:

• To investigate the presence of cephalosporin-resistant Enterobacteriaceae on bedding paper from day-old chicks.
• To identify the specific resistance genes and their mobile genetic elements.
• To assess the potential for transmission of these resistant bacteria and genes within commercial broiler farms.

Main Methods:

• Collection and microbiological examination of 66 meconium-stained bedding paper samples from broiler farms.
• Isolation and identification of cephalosporin-resistant Enterobacteriaceae.
• Conjugation experiments to determine the transferability of resistance genes via plasmids.

Main Results:

• Five samples (7.58%) yielded cephalosporin-resistant Enterobacteriaceae, including Klebsiella pneumoniae and Enterobacter cloacae.
• The blaCTX-M-25 gene, conferring cefotaxime resistance, was identified.
• This gene was transferable via IncA/C plasmids from K. pneumoniae and E. cloacae isolates to Escherichia coli DH5α.

Conclusions:

• Day-old chicks can carry cephalosporin-resistant Enterobacteriaceae on their bedding paper.
• The blaCTX-M-25 gene is present and transferable within this environment.
• This suggests a potential route for the dissemination of antimicrobial resistance genes from poultry to broader environments.