Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
Vet Microbiol. 2019 Dec;239:108446. doi: 10.1016/j.vetmic.2019.108446. Epub 2019 Oct 4.
Plasmid-mediated extended-spectrum β-lactamase and AmpC β-lactamase (ESBL/pAmpC) producing bacteria are present at all levels of the broiler production pyramid. Young birds can be found positive for ESBL/pAmpC-producing Escherichia coli shortly after arrival at farm. The aim of this study was to determine the effect of different challenge doses of ESBL/pAmpC-producing E. coli on time-until-colonization and the level of excretion in young broilers. One-day-old broilers (specific-pathogen free (SPF) and conventional Ross 308) were housed in isolators and challenged with 0.5 ml ESBL/pAmpC-producing E. coli strains of varying doses (10-10 CFU/ml). Presence and concentration (CFU/gram feces) of ESBL/pAmpC-producing E. coli and total E. coli were determined longitudinally from cloacal swabs, and in cecal content 72 h after challenge. Higher challenge doses resulted in shorter time-until-colonization. However, even the lowest dose (10 CFU/ml) resulted in colonization of the broilers which excreted >10 CFU/gram feces 72 h after inoculation. Conventional broilers were colonized later than SPF broilers, although within 72 h after challenge all broilers were excreting ESBL/pAmpC-producing E. coli. A probabilistic model was used to estimate the probability of colonization by initial inoculation or transmission. The higher the dose the higher the probability of excreting ESBL/pAmpC-producing E. coli as a result of inoculation. In conclusion, low initial doses of ESBL/pAmpC-producing E. coli can result in rapid colonization of a flock. Interventions should thus be aimed to eliminate ESBL/pAmpC-producing bacteria in the environment of the hatchlings and measures focusing at reducing colonization and transmission of ESBL/pAmpC-producing E. coli should be applied shortly after hatching.
质粒介导的超广谱β-内酰胺酶和 AmpC β-内酰胺酶（ESBL/pAmpC）产生菌存在于肉鸡生产金字塔的各个层次。雏鸡在到达农场后不久即可检测到产 ESBL/pAmpC 的大肠杆菌呈阳性。本研究旨在确定不同剂量的产 ESBL/pAmpC 大肠杆菌对雏鸡定植时间和排泄水平的影响。将 1 日龄 SPF 和常规 Ross 308 肉鸡分别饲养在隔离器中，并以不同剂量（10-10 CFU/ml）的产 ESBL/pAmpC 大肠杆菌菌株 0.5 ml 进行攻毒。从泄殖腔拭子中纵向检测产 ESBL/pAmpC 大肠杆菌和总大肠杆菌的存在和浓度（CFU/克粪便），并在攻毒后 72 小时检测盲肠内容物中的产 ESBL/pAmpC 大肠杆菌和总大肠杆菌。较高的攻毒剂量导致定植时间缩短。然而，即使是最低剂量（10 CFU/ml）也导致了肉鸡的定植，攻毒后 72 小时，这些肉鸡的粪便排泄量超过 10 CFU/克。常规肉鸡比 SPF 肉鸡定植晚，但在攻毒后 72 小时内，所有肉鸡均排泄产 ESBL/pAmpC 大肠杆菌。使用概率模型估计初始接种或传播引起定植的概率。剂量越高，接种后排泄产 ESBL/pAmpC 大肠杆菌的概率越高。总之，低剂量的产 ESBL/pAmpC 大肠杆菌初始接种即可迅速定植鸡群。因此，应针对孵化环境中的 ESBL/pAmpC 产生菌进行干预，并在孵化后不久采取减少产 ESBL/pAmpC 大肠杆菌定植和传播的措施。
