Li Tianmin, Castañeda Claudia D, Miotto Julio, McDaniel Chris, Kiess Aaron S, Zhang Li
Department of Poultry Science, Mississippi State University, Mississippi State, MS, 39762, USA.
Department of Poultry Science, Mississippi State University, Mississippi State, MS, 39762, USA.
Poult Sci. 2021 Mar;100(3):100903. doi: 10.1016/j.psj.2020.11.072. Epub 2020 Dec 10.
Avian pathogenic Escherichia coli (APEC) causes colibacillosis in poultry, which has been traditionally controlled by the prophylactic in-feed supplementation of antibiotics. However, antibiotics are being removed from poultry diets owing to the emergence of multidrug-resistant (MDR) bacteria. Therefore, alternatives to control APEC are required. This study aimed to evaluate the effects of in ovo inoculation of probiotics on the incidence of APEC in broilers and evaluate the virulence and antimicrobial resistance properties of the APEC isolates. On embryonic day 18, 4 in ovo treatments (T) were applied: T1 (Marek's vaccine [MV]), T2 (MV and Lactobacillus animalis), T3 (MV and Lactobacillus reuteri), and T4 (MV and Lactobacillus rhamnosus). A total of 180 male broilers per treatment were randomly placed in 10 pens. The heart, liver, spleen, and yolk sac were collected on day 0, 14, 28, and 42. Presumptive E. coli isolates were confirmed by real-time PCR. The positive isolates were screened for the APEC-related genes (iroN, ompT, hlyF, iss, and iutA), and E. coli isolates containing one or more of these genes were identified as APEC-like strains. A total of 144 APEC-like isolates were isolated from 548 organ samples. No differences (P > 0.05) among treatments were observed for the incidence of APEC-like strains in all organs when averaged over sampling days. However, when averaged over treatments, the incidence in the heart, liver, and yolk sac was different among sampling days; a significant increase was observed in these organs on day 14 compared with day 0. Twenty-five antimicrobial resistance genes were evaluated for all APEC-like isolates, and 92.4% of the isolates carried at least one antimicrobial resistance gene. Thirty-seven isolates were then selected for antimicrobial susceptibility testing; MDR strains accounted for 37.8% of the isolates. In conclusion, the in ovo inoculation of a single probiotic strain did not confer protection against APEC strains in broilers. The high prevalence of MDR isolates indicates that further research on antibiotic alternatives is required to prevent APEC infections in broilers.
禽致病性大肠杆菌（APEC）可导致家禽发生大肠杆菌病，传统上通过在饲料中预防性添加抗生素来控制该病。然而，由于多重耐药（MDR）细菌的出现，抗生素正从家禽日粮中被去除。因此，需要控制APEC的替代方法。本研究旨在评估在鸡胚内接种益生菌对肉鸡中APEC发病率的影响，并评估APEC分离株的毒力和抗菌药物耐药特性。在胚胎第18天，进行了4种鸡胚内处理（T）：T1（马立克氏疫苗[MV]）、T2（MV和动物乳杆菌）、T3（MV和罗伊氏乳杆菌）和T4（MV和鼠李糖乳杆菌）。每种处理共180只雄性肉鸡被随机放入10个鸡舍。在第0、14、28和42天采集心脏、肝脏、脾脏和卵黄囊。通过实时PCR确认疑似大肠杆菌分离株。对阳性分离株进行APEC相关基因（iroN、ompT、hlyF、iss和iutA）筛查，含有这些基因中一个或多个的大肠杆菌分离株被鉴定为APEC样菌株。从548个器官样本中共分离出144株APEC样分离株。在所有采样日平均后，各处理间APEC样菌株在所有器官中的发病率无差异（P>0.05）。然而，在处理平均后，心脏、肝脏和卵黄囊的发病率在不同采样日有所不同；与第0天相比，第14天这些器官中的发病率显著增加。对所有APEC样分离株评估了25种抗菌药物耐药基因，92.4%的分离株携带至少一种抗菌药物耐药基因。然后选择37株分离株进行药敏试验；多重耐药菌株占分离株的37.8%。总之，在鸡胚内接种单一益生菌菌株并不能为肉鸡提供针对APEC菌株的保护。多重耐药分离株的高流行率表明需要对抗生素替代物进行进一步研究以预防肉鸡中的APEC感染。
