Emergence of Acholeplasma laidlawii Infection in Ducks: Isolation and Colonization Potential

Acholeplasma laidlawii is a Mycoplasma species widely distributed in the environment. It is often regarded as an opportunistic pathogen capable of causing respiratory infections in animals and humans. To date, only a few studies have reported A. laidlawii infection in poultry. In the present study, an A. laidlawii strain was isolated from the lungs and trachea of diseased ducks presenting with air sac lesions. Antimicrobial susceptibility testing revealed that the isolate was susceptible to tylvalosin, tylosin, and valnemulin, with relatively low minimum inhibitory concentrations (MICs). The pathogenicity of the isolate was evaluated using specific-pathogen-free (SPF) ducks via subcutaneous inoculation. No clinical signs were observed during the experimental period. Oral and cloacal swabs, as well as tissue samples, were tested by PCR. The results showed that the pathogen was detectable in swabs from 5 to 21 days post-inoculation (dpi), and all lung and tracheal samples from infected ducks tested positive. Histopathological examination of the lungs and trachea revealed pathological changes in both tissues. Collectively, these findings demonstrated that A. laidlawii was capable of colonizing ducks and inducing mild histopathological changes, suggesting that this pathogen might pose an epidemiological risk in duck farming. Furthermore, these results indicate that A. laidlawii could colonize ducks, underscoring the need for continued surveillance to monitor for emerging pathogens in ducks.