Mycoplasma gallisepticum is a bacterium that causes chronic respiratory disease in chickens and sinusitis in turkeys. M. gallisepticum infection can lead to considerable economic losses in the poultry industry because it results in reduced weight gain and egg production, as well as increased embryo mortality, in commercial birds. Macrolides, such as tylosin, are a class of antibiotics that are important for the clinical treatment of M. gallisepticum infection. However, long-term and often incorrect use of macrolides has resulted in increased M. gallisepticum resistance, which has reduced the clinical efficacy of the drugs.

Macrolides can interact with the 50S ribosomal subunit to inhibit protein synthesis and a mutation of the gene site in the central loop of domain V in 23S rRNA reportedly contributes to the generation of macrolides resistance in M. gallisepticum. Additionally, in 23S rRNA, a single site mutation in hairpin 35 of domain II could confer resistance to macrolides. Mutations in the genes encoding ribosomal protein L4 or L22 may also cause resistance by preventing macrolides binding to the ribosome. In our laboratory, we obtained M. gallisepticum strains that were highly resistant to macrolides by using in vitro selection and we identified point mutations in 23S rRNA in macrolide-resistant mutants. Although gene expression has been profiled in the macrolide-resistant and susceptible parent strains, little is known about the global proteome alterations associated with resistance in M. gallisepticum mutants. Determining these proteome changes could lead to improved understanding of antibiotic resistance mechanisms.

Here, we used in vitro selection and performed comparative proteomics analysis of tylosin-resistant and parent strains of M. gallisepticum to investigate the proteome alterations associated with resistance mutations. Our findings indicate that specific enzymatic activity could lead to tylosin resistance in M. gallisepticum.