Veterinary Preclinical Centre, Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria.
Avian Pathol. 1998;27(5):505-11. doi: 10.1080/03079459808419375.
We have developed a reliable aerosol challenge method for reproduction of avian colibacillosis. This method involves intranasal administration of infectious bronchitis virus (IBV) to 1-day-old birds followed by three aerosol administrations of .E. coli at 3 to 4-day intervals. In four separate experiments there was no significant difference in virulence for a single isolate of .E. coli (E3) whereas four other field isolates of .E. coli ranged from highly virulent to avirulent. We also observed that the dominant .E. coli population isolated from 1-day-old birds in a flock of broiler breeders was highly virulent but that the dominant .E. coli population isolated from birds in the same flock 2 weeks later was avirulent. The dominant .E. coli population isolated from 1-day-old birds in this flock was sensitive to all of the antimicrobial agents tested whereas the dominant .E. coli population in the 2-week-old birds was multiresistant. A previous study has shown that it is likely that the changed resistance pattern of the dominant .E. coli population in the flock was linked to the administration of antimicrobial agents.
我们已经开发出一种可靠的气溶胶挑战方法来重现禽大肠杆菌病。该方法包括将传染性支气管炎病毒（IBV）鼻内给药给 1 日龄的雏鸡，然后在 3 至 4 天的间隔内进行三次气溶胶给药。在四项独立的实验中，单一分离株的致病性大肠杆菌（E3）没有显著差异，而其他四种大肠杆菌的田间分离株从高致病性到非致病性不等。我们还观察到，在一群肉鸡种鸡群中，从 1 日龄雏鸡中分离出的优势大肠杆菌种群高度致病性，但 2 周后从同一鸡群中分离出的优势大肠杆菌种群无致病性。从这群 1 日龄雏鸡中分离出的优势大肠杆菌种群对所有测试的抗菌药物均敏感，而从 2 周龄鸡中分离出的优势大肠杆菌种群则具有多重耐药性。先前的一项研究表明，该鸡群中优势大肠杆菌种群的耐药模式变化很可能与抗菌药物的使用有关。
