[Detection and Distribution Characteristics of Antibiotic Resistance Genes in Companion Animals]

To explore the distribution characteristics of antimicrobial resistance genes (ARGs) in companion animals and accumulate scientific data for preventing the transmission of ARGs between companion animals and humans.

From December 2023 to October 2024, fecal or rectal swab samples were collected from companion animals at a large pet hospital in Chengdu. PCR and qPCR were used to detect 9 ARGs types (including 20 ARGs). The distribution characteristics of ARGs in companion animals with different species, gender, age, clinical status and the mobile genetic element intΙ1 carrying status were analyzed based on the data of ARGs quantities, detection rates and relative abundance.

A total of 136 samples were collected. The median (interquartile range) of ARGs detected per animal was 6.5 (5, 9). Tetracycline and aminoglycoside resistance genes had higher detection rates, with tetQ and tetW having the highest detection rates (both at 90.44%), and relative abundance > 10^－2. This was followed by tetM (67.65%) and aph3 (58.82%), with relative abundance > 10^－3. Female animals had higher relative abundance of sul2, strB, and cmlA than male animals. The detection rate of sul1 in animals aged 0-2 months was higher than that in animals aged 12 months and above (P = 0.007). The detection rates of macrolide resistance genes and ermB in animals aged 3-5 months were higher than those in animals aged 12 months and above (P < 0.001). Animals carrying intΙ1 had higher ARGs detection quantities, detection rates and relative abundance of multiple ARGs than those not carrying intΙ1, with all differences being statistically significant.

Companion animals commonly carry ARGs, with tetracycline and aminoglycoside resistance genes having high detection rates. Age and the carriage of intΙ1 are important factors influencing the distribution of ARGs in companion animals.