Department of Veterinary Microbiology and Preventive Medicinea, Iowa State University, Ames, Iowa, USA.
Antimicrob Agents Chemother. 2012 Mar;56(3):1300-8. doi: 10.1128/AAC.05516-11. Epub 2011 Dec 19.
Campylobacter jejuni is a major zoonotic pathogen transmitted to humans via the food chain and is prevalent in chickens, a natural reservoir for this pathogenic organism. Due to the importance of macrolide antibiotics in clinical therapy of human campylobacteriosis, development of macrolide resistance in Campylobacter has become a concern for public health. To facilitate the control of macrolide-resistant Campylobacter, it is necessary to understand if macrolide resistance affects the fitness and transmission of Campylobacter in its natural host. In this study we conducted pairwise competitions and comingling experiments in chickens using clonally related and isogenic C. jejuni strains, which are either susceptible or resistant to erythromycin (Ery). In every competition pair, Ery-resistant (Ery(r)) Campylobacter was consistently outcompeted by the Ery-susceptible (Ery(s)) strain. In the comingling experiments, Ery(r) Campylobacter failed to transmit to chickens precolonized by Ery(s) Campylobacter, while isogenic Ery(s) Campylobacter was able to transmit to and establish dominance in chickens precolonized by Ery(r) Campylobacter. The fitness disadvantage was linked to the resistance-conferring mutations in the 23S rRNA. These findings clearly indicate that acquisition of macrolide resistance impairs the fitness and transmission of Campylobacter in chickens, suggesting that the prevalence of macrolide-resistant C. jejuni will likely decrease in the absence of antibiotic selection pressure.
空肠弯曲菌是一种主要的人畜共患病病原体，通过食物链传播给人类，在鸡中很常见，是这种病原体的天然宿主。由于大环内酯类抗生素在人类弯曲菌病的临床治疗中非常重要，因此弯曲菌对大环内酯类药物的耐药性发展引起了公众健康的关注。为了便于控制耐大环内酯类弯曲菌，有必要了解大环内酯类耐药性是否会影响其在天然宿主中的适应性和传播能力。在这项研究中，我们使用克隆相关和同源的空肠弯曲菌菌株在鸡中进行了成对竞争和混合实验，这些菌株对红霉素（Ery）敏感或耐药。在每一对竞争菌株中，红霉素耐药（Ery(r)）弯曲菌始终被红霉素敏感（Ery(s)）菌株所淘汰。在混合实验中，红霉素耐药（Ery(r)）弯曲菌无法传播到被红霉素敏感（Ery(s)）弯曲菌定植的鸡中，而同源的红霉素敏感（Ery(s)）弯曲菌能够传播并在被红霉素耐药（Ery(r)）弯曲菌定植的鸡中建立优势。适应性劣势与 23S rRNA 上的耐药性赋予突变有关。这些发现清楚地表明，获得大环内酯类耐药性会损害弯曲菌在鸡中的适应性和传播能力，这表明在没有抗生素选择压力的情况下，大环内酯类耐药空肠弯曲菌的流行率可能会降低。
