Waterman S R, Small P L
Microscopy Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana 59840 USA.
Infect Immun. 1996 Jul;64(7):2808-11. doi: 10.1128/iai.64.7.2808-2811.1996.
Shiga-like toxin-producing Escherichia coli (SLTEC) strains are an important group of enteric pathogens. In this study we have examined the abilities of 58 SLTEC isolates to survive at pH 2.5 and found 13 of these isolates to be defective in acid resistance. Introduction of rpoS on a plasmid conferred acid resistance to the majority of the acid-sensitive isolates. The rpoS genes from two of these isolates were sequenced; both isolates contained lesions in the rpoS gene resulting in a nonfunctional RpoS. These results show that mutant rpoS alleles exist in natural populations of E. coli. Such mutations may play an important role in determining the infective dose of SLTEC and suggest that isolates may vary in infectivity.
产志贺样毒素大肠杆菌(SLTEC)菌株是一类重要的肠道病原体。在本研究中,我们检测了58株SLTEC分离株在pH 2.5环境下的存活能力,发现其中13株分离株存在耐酸性缺陷。将rpoS基因导入质粒可使大多数酸敏感分离株获得耐酸性。对其中两株分离株的rpoS基因进行了测序;这两株分离株的rpoS基因均存在损伤,导致RpoS功能丧失。这些结果表明,突变的rpoS等位基因存在于大肠杆菌的自然群体中。此类突变可能在决定SLTEC的感染剂量方面发挥重要作用,并提示分离株的传染性可能存在差异。