鼠伤寒沙门氏菌在外环境中的存活能力

THE VIABILITY OF Salmonella typhimurium IN ENVIRONMENT

通过模拟试验表明,鼠伤寒沙门氏菌在干燥布片上28天仍有存活,在含水布片上仍可生长繁殖。胃液在pH2时,对该菌有良好杀菌作用,pH值大干3.5,杀菌作用消失。加热至65℃经5分钟,或煮沸20秒,或以消毒剂作用10～120秒,可使该菌杀灭指数达6.0。

In order to improve the prevention of Salmonella typhimurium infection in hospital, the viability of the bacteria in environment was observed in laboratory. It was found in experiment that S. typhimurium on dry cloth carrier(>10~6cfu/carrier) decreased by 90% after 4 days and by 99% after 7 days, but could still be detected in small number after 28 days (18～25℃, RH 60%). In contrast, the bacteria on wet cloth carrier could continue to grow and multiply, went through a logarithmic phase during the period of 12～24 hr and a stationary phase after 2 days, and maintained a certain number on 28th day. The pH of gastric juice could influence the ability of the juice to kill S. typhimurium. The killing index was higher than 5.92 at pH 2 with a 5 min contact time, decreased to 1.60 at pH 2.5, 0.49 at pH 3 and lower than 3.0 at pH 3.5. The results indicate that gastric function exerts certain influence on killing of S. typhimurium. Since the pH of gastric juice of one-week neonates is higher than 4 and increases to higher than 5.3 after taking milk, they are liable to be infected. The killing index of heating to 65℃ for 5 min or boiling (98℃) for 20sec in killing S. typhimurium could reach 6.0, while that of 0.1% bromogeramine, 60% ethanol, 1% lysol or 0.05% peracetic acid with a 10 sec contact time, or chlorine-containing disinfectant solution containing 50mg/L available chlorine with a 2min contact time could also be as high as 6.0. The results indicate that in order to prevent the epidemic of S. typhirnuriurn infection in hospital, it is desirable to improve the disinfection of food, tableware, medical and nursing supplies and environment, especially the baby room and pediatric ward. Heating and treatment with commondisinfectants can fullfill the requirements.