Kasturi P K, Panigrahi D, Ganguly N K, Nayak N, Ayyagari A, Khuller M
Department of Medical Microbiology, Postgraduate Institute of Medical Education & Research, Chandigarh.
Indian J Med Res. 1991 May;93:166-70.
Twenty five isolates of S. typhimurium from clinical specimens were studied for markers of virulence. Three of five isolates from blood, both isolates from CSF and urine and only two of fifteen isolates from faeces were positive for fluid accumulation in rabbit ileal loop. All these strains produced an enterotoxic principle, antigenically related to cholera coli family of enterotoxins, as detected by latex agglutination and immuno-dot-blot tests. Polymyxin-B treated 6 h cultures yielded the best toxin. All 5 blood isolates, both CSF isolates and one of the two urine isolates showed low LD50 indicating high virulence. The study thus revealed that some strains of S. typhimurium are more virulent and produce more enterotoxins. These strains invade the intestinal mucosa potently and lead to extra-intestinal manifestations. The low virulent strains, on the other hand, are confined to the intestine and cause mild/moderate gastroenteritis. Enzyme assays were done in 5 representative strains of good, moderate and low toxin producers. Catalase and superoxide dismutase assays did not show any correlation with toxin production, thus suggesting that the enzyme production is unlikely to be a reliable indicator of the virulence for S. typhimurium.
对从临床标本中分离出的25株鼠伤寒沙门氏菌进行了毒力标志物研究。从血液中分离出的5株菌株中有3株、从脑脊液和尿液中分离出的所有菌株以及从粪便中分离出的15株菌株中只有2株在兔回肠袢中出现液体蓄积呈阳性。通过乳胶凝集试验和免疫斑点印迹试验检测，所有这些菌株都产生了一种肠毒素，其抗原性与霍乱弧菌家族的肠毒素相关。用多粘菌素B处理6小时的培养物产生的毒素效果最佳。所有5株血液分离株、2株脑脊液分离株以及2株尿液分离株中的1株显示出低半数致死剂量（LD50），表明毒力高。该研究因此揭示，一些鼠伤寒沙门氏菌菌株毒力更强且产生更多肠毒素。这些菌株能有力地侵入肠黏膜并导致肠外表现。另一方面，低毒力菌株局限于肠道，引起轻度/中度肠胃炎。对5株分别代表高产毒、中产毒和低产毒的典型菌株进行了酶活性测定。过氧化氢酶和超氧化物歧化酶活性测定结果与毒素产生没有任何相关性，因此表明酶的产生不太可能是鼠伤寒沙门氏菌毒力的可靠指标。
