Identification and Antimicrobial Susceptibility of Mycoplasma capricolum subsp. capripneumoniae Isolates from China...

Respiratory diseases induced by Mycoplasma species, mainly Mycoplasma capricolum subsp. capripneumoniae (Mccp) and Mycoplasma ovipneumonia (Mo), pose a major threat to goat/sheep farming. This study investigated the biological characteristics and antimicrobial susceptibility of Mccp isolates that suddenly spread extensively in China in the first half of 2024. A total of 34 Mccp isolates were obtained from goats with suspected contagious caprine pleuropneumonia (CCPP) across multiple provinces during 2024-2025. All isolates were purified and confirmed via a PCR targeting the arcD gene and exhibited characteristic "fried egg" colony morphology. Phylogenetic analysis based on the arcD gene and multi-locus sequence analysis (MLSA) of eight genetic loci revealed that the circulating strains shared high homology and belonged to Group 1 within Lineage 1, which showed a close genetic relationship with isolates from Qatar and the United Arab Emirates, while differing from previously reported strains in China. Antimicrobial susceptibility testing against nine antimicrobial drugs indicated that the Mccp isolates generally exhibited low resistance levels. However, some strains showed reduced susceptibility to florfenicol and lincomycin. These findings highlight the emergence of a genetically distinct Mccp lineage in China and underscore the importance of ongoing surveillance, strain characterization, and prudent antimicrobial use in CCPP control.