Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Ga, USA.
Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX, USA.
Sci Rep. 2020 Jan 22;10(1):911. doi: 10.1038/s41598-020-57479-9.
The practice of prophylactic administration of a macrolide antimicrobial with rifampin (MaR) to apparently healthy foals with pulmonary lesions identified by thoracic ultrasonography (i.e., subclinically pneumonic foals) is common in the United States. The practice has been associated epidemiologically with emergence of R. equi resistant to MaR. Here, we report direct evidence of multi-drug resistance among foals treated with MaR. In silico and in vitro analysis of the fecal microbiome and resistome of 38 subclinically pneumonic foals treated with either MaR (n = 19) or gallium maltolate (GaM; n = 19) and 19 untreated controls was performed. Treatment with MaR, but not GaM, significantly decreased fecal microbiota abundance and diversity, and expanded the abundance and diversity of antimicrobial resistance genes in feces. Soil plots experimentally infected with Rhodococcus equi (R. equi) and treated with MaR selected for MaR-resistant R. equi, whereas MaR-susceptible R. equi out-competed resistant isolates in GaM-treated or untreated plots. Our results indicate that MaR use promotes multi-drug resistance in R. equi and commensals that are shed into their environment where they can persist and potentially infect or colonize horses and other animals.
在美国，对经胸部超声检查发现肺部病变（即亚临床肺炎驹）的健康幼驹预防性给予大环内酯类抗菌药物与利福平（MaR）联合治疗的做法很常见。该做法与马红球菌对 MaR 的耐药性出现呈流行病学相关。在此，我们报告了马红球菌治疗幼驹中出现多药耐药的直接证据。对 38 例经 MaR（n = 19）或镓麦芽糖酸盐（GaM；n = 19）治疗的亚临床肺炎驹和 19 例未治疗对照者的粪便微生物组和抗药组进行了体内和体外分析。与 GaM 治疗不同，MaR 治疗显著降低了粪便微生物群的丰度和多样性，并扩大了粪便中抗菌药物耐药基因的丰度和多样性。用马红球菌进行土壤接种实验并给予 MaR 治疗选择了马红球菌耐药株，而 GaM 治疗或未治疗的土壤中则存在马红球菌敏感株与耐药株竞争。我们的结果表明，MaR 的使用促进了马红球菌及其环境中脱落的共生菌的多药耐药性，这些耐药菌可能在环境中持续存在并潜在地感染或定植马和其他动物。
