Shivaramaiah S, Wolfenden R E, Barta J R, Morgan M J, Wolfenden A D, Hargis B M, Téllez G
Department of Poultry Science, University of Arkansas, Fayetteville, AR 72701, USA.
Avian Dis. 2011 Jun;55(2):319-23. doi: 10.1637/9604-112910-ResNote.1.
Necrotic enteritis (NE) caused by Clostridium perfringens (CP) in poultry is an important bacterial disease in terms of economic implications. The disease is multifactorial and is invariably associated with predisposing factors. In the present experiments, we investigated the potential predisposing role of neonatal Salmonella Typhimurium (ST) infection for NE-associated mortality in a laboratory challenge model. In two experiments, day-of-hatch chicks were randomly assigned to four groups: Group 1, nonchallenged control; Group 2, chickens received Eimeria maxima (EM) and CP; Group 3, chickens received EM and CP and were also challenged with ST at day 1 of age; Group 4, chickens received EM and CP and were also challenged with ST at day 17 of age. Challenged groups received an oral dose of EM at 18 days of age and CP (10(8) colony-forming units/chick) at 22-23 days of age. When compared to EM and CP, chicks challenged with ST (day 1) had increased NE-associated mortality and CP-associated lesion scores (P < 0.05) in both experiments. Furthermore, body weight and body weight gain were lower (P < 0.05) in chicks infected with ST (day 1) in the first experiment, even though no differences (P > 0.05) were observed in weight gain in the second experiment. Chicks challenged with ST (day 17) were similar to the EM and CP group in all of the above-mentioned parameters, indicating that a paratyphoid infection in younger chicks remarkably alters the susceptibility to secondary bacterial infections. Based on this work, the authors suggest that an ST infection early in the age of a chick may be important for altering susceptibility to NE, an observation that may be useful from the perspective of experimental reproduction of this disease and, perhaps, as an economically important reason to address the problem of paratyphoid Salmonella infections in young chicks.
由产气荚膜梭菌（CP）引起的家禽坏死性肠炎（NE）是一种具有重要经济影响的细菌性疾病。该疾病是多因素的，并且总是与易感因素相关。在本实验中，我们在实验室攻毒模型中研究了新生鼠伤寒沙门氏菌（ST）感染对NE相关死亡率的潜在易感作用。在两个实验中，孵化当天的雏鸡被随机分为四组：第1组，未攻毒对照组；第2组，鸡接种巨型艾美耳球虫（EM）和CP；第3组，鸡接种EM和CP，并在1日龄时用ST攻毒；第4组，鸡接种EM和CP，并在17日龄时用ST攻毒。攻毒组在18日龄时口服一剂EM，在22 - 23日龄时口服CP（每只鸡10⁸菌落形成单位）。与EM和CP组相比，在两个实验中，用ST（1日龄）攻毒的雏鸡NE相关死亡率和CP相关病变评分均升高（P < 0.05）。此外，在第一个实验中，感染ST（1日龄）的雏鸡体重和体重增加较低（P < 0.05），尽管在第二个实验中体重增加未观察到差异（P > 0.05）。用ST（17日龄）攻毒的雏鸡在上述所有参数方面与EM和CP组相似，这表明幼雏中的副伤寒感染显著改变了对继发性细菌感染的易感性。基于这项工作，作者认为雏鸡早期的ST感染可能对改变NE易感性很重要，这一观察结果从该疾病的实验复制角度来看可能有用，并且也许作为解决幼雏副伤寒沙门氏菌感染问题的一个重要经济原因。
