Wang C, Zhang L F, Austin F W, Boyle C R
Research Program and Diagnostic Laboratory Services, College of Veterinary Medicine, Mississippi State University, MS 39762, USA.
Am J Vet Res. 1998 Sep;59(9):1125-8.
To characterize Listeria monocytogenes from tissues of channel catfish for their ability to cause hemolysis and grow intracellularly in mouse macrophages.
15 isolates from processed fillets and 15 isolates from the brain, spleen, and kidneys.
Serotype and hemolytic activity of L monocytogenes isolates were evaluated, using plate agglutination and CAMP tests, respectively. Invasiveness of L monocytogenes was determined by inoculating each strain or isolate on J774A.1 macrophage cells. Infected cells were incubated for 0 or 3 hours and lysed; then 100 gli of the lysate was plated onto a brain heart infusion agar plate. Colony counts for each strain or isolate were analyzed statistically.
Of 30 isolates, 19 were serotype 1 and 11 were serotype 4. Mouse J774A.1 macrophages were inoculated with catfish isolates, a wild-type (EGD) or a nonhemolytic strain of L monocytogenes. Seventy-three percent (11/15) of isolates originating from catfish organs and 100% (15/15) of isolates originating from fillets were not significantly different from the wild-type EGD strain. The nonhemolytic L monocytogenes strain used as a negative control failed to replicate. Intracellular growth of all L monocytogenes isolates decreased after an additional 3-hour incubation period with medium containing 50 [microg/ml of gentamicin.
Similar to the wild-type EGD strain, most channel catfish L monocytogenes isolates were hemolytic, serotype 1 or 4, and were invasive for mouse J774A.1 macrophages.
monocytogenes growth in mouse macrophages may serve as an in vitro model for determining virulence of isolates from food products or environments.
鉴定来自斑点叉尾鮰组织的单核细胞增生李斯特菌引起溶血及在小鼠巨噬细胞内生长的能力。
从加工鱼片分离出15株菌株，从脑、脾脏和肾脏分离出15株菌株。
分别采用平板凝集试验和CAMP试验评估单核细胞增生李斯特菌分离株的血清型和溶血活性。通过将每种菌株或分离株接种到J774A.1巨噬细胞上来测定单核细胞增生李斯特菌的侵袭性。将感染的细胞孵育0或3小时后裂解；然后将100 μl裂解物接种到脑心浸液琼脂平板上。对每种菌株或分离株的菌落计数进行统计学分析。
30株分离株中，19株为血清型1，11株为血清型4。用斑点叉尾鮰分离株、野生型（EGD）或单核细胞增生李斯特菌非溶血菌株接种小鼠J774A.1巨噬细胞。源自斑点叉尾鮰器官的分离株中有73%（11/15）以及源自鱼片的分离株中有100%（15/15）与野生型EGD菌株无显著差异。用作阴性对照的非溶血单核细胞增生李斯特菌菌株未能复制。在含有50 μg/ml庆大霉素的培养基中再孵育3小时后，所有单核细胞增生李斯特菌分离株的细胞内生长均减少。
与野生型EGD菌株相似，大多数斑点叉尾鮰单核细胞增生李斯特菌分离株具有溶血活性，血清型为1或4，并且可侵袭小鼠J774A.1巨噬细胞。
单核细胞增生李斯特菌在小鼠巨噬细胞内的生长可作为一种体外模型，用于确定食品或环境分离株的毒力。
