Mycoplasma hyopneumoniae (M. hyopneumoniae) causes significant economic losses in the swine industry. Antibiotics with activity against Mycoplasma spp. are employed for disease mitigation and pathogen elimination. However, veterinarians are often challenged with the detection of M. hyopneumoniae by PCR after antibiotic treatment, thus raising the question whether the bacterium is still infectious. The objective of this study was to evaluate the effect of tulathromycin treatment on M. hyopneumoniae detection and infectious potential during the acute and chronic phases of infection. For each infection phase, one age-matched naïve gilt was placed in contact with one M. hyopneumoniae infected gilt that was either treated with tulathromycin, treated and vaccinated, or non-treated, for 14 days. Four replicates per treatment group were performed for each infection phase. A numerical reduction in relative bacterial load was observed in acutely treated gilts compared to non-treated gilts. The rate at which naïve gilts became infected with M. hyopneumoniae was numerically reduced when co-housed with treated, acutely infected gilts compared to those housed with non-treated, infected gilts. During the chronic infection phase, M. hyopneumoniae was detected by PCR in more than 50 % of treated infected gilts and persisted for up to three months post-treatment. Transmission was not detected in all treatment groups however, the possibility that the pathogen was infectious could not be completely ruled out. Further research focused on assessing M. hyopneumoniae detection and viability post-treatment is necessary to guide control and elimination efforts.

猪肺炎支原体（M. hyopneumoniae）给养猪业造成重大经济损失。具有抗支原体活性的抗生素。用于减轻疾病和消除病原体。然而，兽医经常面临抗生素治疗后通过 PCR检测猪肺炎支原体的挑战，从而引发了该细菌是否仍具有传染性的问题。本研究的目的是评估土拉霉素治疗对急性和慢性感染阶段猪肺炎支原体检测和感染潜力的影响。对于每个感染阶段，将一只年龄匹配的幼猪与一只猪肺炎支原体接触用 tulathromycin 治疗并接种疫苗或未治疗 14 天的受感染小母猪。对于每个感染阶段，每个处理组进行四次重复。与未处理的小母猪相比，在急性处理的小母猪中观察到相对细菌负荷的数值降低。与饲养未经治疗的感染后备母猪的母猪相比，与经过处理的急性感染后备母猪共同饲养的幼猪感染M. hyopneumoniae的比率在数量上有所降低。在慢性感染阶段，M. hyopneumoniae在超过 50% 的受感染小母猪中通过 PCR 检测到，并在治疗后持续长达三个月。然而，并未在所有治疗组中检测到传播，不能完全排除病原体具有传染性的可能性。进一步的研究侧重于评估M. hyopneumoniae检测和生存力后处理对于指导控制和消除工作是必要的。