Mycoplasma gallisepticum (MG) causes chronic respiratory disease in chickens, leading to severe economic losses to the poultry industry. Currently the disease is managed with antimicrobials and vaccination; however, emergence of multi-drug resistant Mycoplasma and the limited effect of vaccines necessitate development of novel approaches. A library of 4,182 small molecules (SMs) was screened for identification of narrow spectrum anti-MG compounds using high throughput screening. A total of 584 SMs were identified. Ten SMs possessed low MICs (0.78–100 μM) with efficacy against multiple MG strains and MG biofilm. These 10 SMs did not affect commensal/probiotic bacteria and other avian and foodborne pathogens. They displayed no or little toxicity on the avian macrophage HD-11 cells, human epithelial Caco-2 cells, and chicken red blood cells (RBCs); but, they were effective in reducing MG in chicken RBCs. Six SMs (SM1, SM3−5, and SM9−10) were tested in three-week-old chickens infected with MG (nasal spray; 10⁹ CFU/bird). SM4 and SM9 reduced airsacculitis by 77.2 % and 82.9 %, MG load in the trachea by 0.9 log (p < 0.05) and 2.7 log (p < 0.0001), and tracheal mucosal thickness by 23 % and 61 %, respectively with no impact on the richness and evenness of the cecal (P = 0.6; H = 1.0) and tracheal (P = 0.8; H = 0.8) microbiota compared to the MG-infected controls. Both SM4 and SM9 treatments resulted in a significant alteration in the cell membrane conformation of MG. In conclusion; we identified two novel growth inhibitors of MG that are effective in chickens. These findings will facilitate development of novel antibacterials to control mycoplasmosis in poultry.

鸡毒支原体（MG）引起鸡的慢性呼吸道疾病，给家禽业造成严重的经济损失。目前，该疾病可通过抗菌药物和疫苗接种来控制。然而，多重耐药性支原体的出现疫苗的作用有限，因此必须开发新方法。使用高通量筛选筛选了一个4,182个小分子（SM）的文库，以鉴定窄谱抗MG化合物。总共鉴定了584个SM。十个SM的MIC低（0.78–100μM），可抵抗多种MG菌株和MG生物膜。这10种SM不影响共生/益生菌以及其他禽和食源性病原体。他们对禽巨噬细胞HD-11细胞，人上皮Caco-2细胞和鸡红细胞（RBC）几乎没有毒性。但是，它们可以有效减少鸡肉RBC中的MG。在三周龄感染了MG的鸡中（鼻喷雾剂； 10 ⁹）对六个SM（SM1，SM3-5和SM9-10）进行了测试。CFU /鸟）。SM4和SM9分别降低了77.2％和82.9％的气管炎，气管中的MG负荷分别降低了0.9 log（p <0.05）和2.7 log（p <0.0001），气管粘膜厚度分别降低了23％和61％。与MG感染的对照组相比，盲肠（P = 0.6; H = 1.0）和气管（P = 0.8; H = 0.8）菌群的丰富度和均匀度。SM4和SM9处理均导致MG细胞膜构象的显着改变。结论; 我们确定了两种对鸡有效的新型MG生长抑制剂。这些发现将促进新型抗菌剂的开发，以控制家禽支原体病。