期刊
AVIAN PATHOLOGY
卷 50, 期 5, 页码 436-446出版社
TAYLOR & FRANCIS LTD
DOI: 10.1080/03079457.2021.1962004
关键词
Laying chickens; Escherichia coli; E; coli peritonitis syndrome; biotyping; embryo lethality test; virulent E; coli; LD50
资金
- Stichting AviNed, Nieuwegein, Netherlands
- Vaxxinova Research & Development GmbH, Munster, Germany
Fourteen genetically different chicken Escherichia coli strains were biotyped in hens to examine their ability to induce E. coli peritonitis syndrome (EPS). Strains from bone marrow and pericardium were found to be associated with EPS, while strains from other sources were not. The embryo lethality test showed good reproducibility and can be considered a useful alternative for biotyping E. coli in productive hens.
Fourteen genetically different chicken Escherichia coli strains were biotyped in hens to examine if any E. coli strain at high dose can induce the E. coli peritonitis syndrome (EPS). Moreover, biotyping was performed in embryos and the median lethal dose (LD50) of three strains was determined in hens. Nine strains were obtained from femur marrow and one strain from caecum of hens that had died from EPS. One strain originated from the inflamed pericardium of a broiler and three strains from the cloaca of specified pathogen-free (SPF) broiler breeders. Strains were inoculated intratracheally into separate groups of 32 productive SPF White Leghorn (WL) hens at a dose of 7.8-9.2 log(10) colony forming units (CFU) per hen and into the allantoic cavity of separate groups of 20 SPF WL embryos incubated during 14 days in a dose of 4.2-4.6 log(10) CFU per embryo. The embryo test was replicated. Bone marrow and pericardium strains induced EPS, the other strains did not. Based on mortality in hens, EPS-inducing strains could be classified as very virulent (59-100% mortality), moderately virulent (38% mortality) and low virulent (6% mortality). In productive SPF WL hens, the LD50 of three very virulent strains ranged from <2.7 to 5.3 log(10) CFU. Virulent and avirulent strains killed 60-95% and 0-30% of embryos, respectively. The embryo lethality test, which showed good reproducibility, did not discriminate within virulent strains, but can nevertheless be considered as a useful alternative for biotyping E. coli in productive hens.
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