Czuprynski Charles J, Faith Nancy G, Steinberg Howard
Department of Pathobiological Sciences School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin 53706, USA.
Appl Environ Microbiol. 2002 Jun;68(6):2893-900. doi: 10.1128/AEM.68.6.2893-2900.2002.
Listeriosis is an important food-borne disease that causes high rates of morbidity and mortality. For reasons that are not clear, most large outbreaks of human listeriosis involve Listeria monocytogenes serotype 4b. Relatively little is known about the pathogenesis of listeriosis following gastrointestinal exposure to food-borne disease isolates of L. monocytogenes. In the present study, we investigated the pathogenesis of systemic infection by the food-borne isolate Scott A in an intragastric (i.g.) mouse challenge model. We found that the severity of infection with L. monocytogenes Scott A was increased in mice made neutropenic by administration of monoclonal antibody RB6-8C5. This observation was similar to a previous report on a study with the laboratory strain L. monocytogenes EGD. Prior administration of sodium bicarbonate did not enhance the virulence of L. monocytogenes strain Scott A for i.g. inoculated mice. Following i.g. inoculation of mice, two serotype 4b strains of L. monocytogenes (Scott A and 101M) achieved a greater bacterial burden in the spleen and liver and elicited more severe histopathological damage to those organs than did a serotype 1/2a strain (EGD) and a serotype 1/2b stain (CM). Of the four strains tested, only strain CM exhibited poor survival in synthetic gastric fluid in vitro. The other three strains exhibited similar patterns of survival at pHs of greater than 5 and relatively rapid (<30 min) loss of viability at pHs of less than 5.0. Growth of L. monocytogenes Scott A at temperatures of 12.5 to 37 degrees C did not affect its ability to cause systemic infection in i.g. inoculated mice. These observations suggest that the serotype 4b L. monocytogenes strains Scott A and 101M possess one or more virulence determinants that make them better able to cause systemic infection following inoculation via the g.i. tract than do the serotype 1/2 strains EGD and CM.
李斯特菌病是一种重要的食源性疾病，可导致高发病率和死亡率。由于尚不清楚的原因，大多数人类李斯特菌病的大规模暴发都涉及4b血清型单核细胞增生李斯特菌。对于经胃肠道接触食源性单核细胞增生李斯特菌分离株后李斯特菌病的发病机制，人们了解相对较少。在本研究中，我们在胃内（i.g.）小鼠攻击模型中研究了食源性分离株斯科特A引起全身感染的发病机制。我们发现，通过给予单克隆抗体RB6-8C5使小鼠中性粒细胞减少后，感染单核细胞增生李斯特菌斯科特A的严重程度增加。这一观察结果与先前关于单核细胞增生李斯特菌实验室菌株EGD的一项研究报告相似。预先给予碳酸氢钠并未增强单核细胞增生李斯特菌斯科特A菌株对经胃内接种小鼠的毒力。经胃内接种小鼠后，两种4b血清型单核细胞增生李斯特菌菌株（斯科特A和101M）在脾脏和肝脏中达到了更高的细菌负荷，并对这些器官造成了比1/2a血清型菌株（EGD）和1/2b血清型菌株（CM）更严重的组织病理学损伤。在所测试的四种菌株中，只有CM菌株在体外合成胃液中存活率较低。其他三种菌株在pH值大于5时表现出相似的存活模式，而在pH值小于5.0时活力相对较快（<30分钟）丧失。单核细胞增生李斯特菌斯科特A在12.5至37摄氏度的温度下生长并不影响其在经胃内接种小鼠中引起全身感染的能力。这些观察结果表明，4b血清型单核细胞增生李斯特菌菌株斯科特A和101M拥有一个或多个毒力决定因素，使其在经胃肠道接种后比1/2血清型菌株EGD和CM更能引起全身感染。
