Campylobacteriosis caused by C. jejuni is a serious yet common foodborne disease in the U.S. The prevalence of fluoroquinolone-resistant C. jejuni from poultry has continued to increase despite the withdrawal of fluoroquinolone use in the U.S. poultry industry in 2005. To date, no clear selective pressures that explain this effect have been documented. In this study, we investigated limited bioavailability of iron in poultry and enhanced iron uptake and regulation as potential indirect selective pressures conferring fitness advantages in fluoroquinolone-resistant C. jejuni compared to its susceptible wild-type counterpart. Five fluoroquinolone-susceptible C. jejuni isolates were selected from litter collected from commercial broiler farms. Using antibiotic selection, five fluoroquinolone-resistant strains were created. Relative expressions of six genes involved in iron acquisition and regulation were compared between the resistant and susceptible strains using RT-qPCR under normal and iron-limiting conditions. High variability in the relative gene expressions was observed among the strains, with only one resistant strain showing the consistent upregulation of the measured genes compared to the matching susceptible wild-type. Our results suggest that the hypothesis tested in the study may not be an adequate explanation of the molecular mechanism behind the enhanced fitness of fluoroquinolone-resistant C. jejuni compared to susceptible C. jejuni. This study highlights the need for a better understanding of the complex ecology and dynamics of fluoroquinolone resistance in C. jejuni in poultry environment and warrants an examination of fluoroquinolone-resistant C. jejuni strains recovered from the natural broiler chicken environment.

空肠弯曲杆菌引起的弯曲杆菌病是美国的一种严重但常见的食源性疾病。尽管2005年美国家禽业停止使用氟喹诺酮，但家禽中对氟喹诺酮类耐药的空肠弯曲杆菌的发病率仍在继续增加。已经证明了解释这种作用的选择性压力。在这项研究中，我们调查了家禽中铁的有限生物利用度，并提高了铁的吸收和调节能力，因为潜在的间接选择压力使耐氟喹诺酮空肠弯曲菌与其易受感染的野生型对应物具有适应性优势。五种氟喹诺酮易感空肠弯曲杆菌从商业肉鸡场收集的垫料中选择分离株。使用抗生素选择，创建了五个氟喹诺酮耐药菌株。在正常和铁限制条件下，使用RT-qPCR比较了抗性和易感菌株中涉及铁获得和调节的六个基因的相对表达。在菌株之间观察到相对基因表达的高度可变性，与匹配的易感野生型相比，只有一种抗性菌株显示出所测基因的一致上调。我们的结果表明，研究中检验的假设可能不足以解释氟喹诺酮耐药C适应性增强背后的分子机制。空肠与易感者相比Ç。空肠。这项研究强调需要更好地了解C中氟喹诺酮耐药性的复杂生态学和动力学。空禽环境中的空肠，需要检查从天然肉鸡环境中回收的耐氟喹诺酮空肠弯曲杆菌菌株。