Enhanced virulence of Escherichia coli bearing a site-targeted mutation in the major structural subunit of type 1 fimbriae

A. K. May, C. A. Bloch, R. G. Sawyer, M. D. Spengler, T. L. Pruett

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Type 1 fimbriae promote enterobacterial adherence to a variety of mammalian cells and are thought to play an important role in the establishment of various extraintestinal infections. Whether or not this adhesin has a role in the pathogenesis of peritoneal Escherichia coli infections, such as those initiated by bowel leakage during intraabdominal surgery, is unclear. By using two genetically engineered E. coli strains, each bearing an antibiotic resistance element inserted at a different site within the type 1 fimbria operon, we examined the role of type 1 fimbriation in intraperitoneal infection in rats. A permanently nonfimbriated insertion mutant was compared with an analogously constructed normally fimbriated one. After intraperitoneal inoculation of adult rats, the permanently nonfimbriated mutant produced mortality more rapidly and resulted in a greater number of culturable organisms from both the peritoneum and the blood. Moreover, the differences between these two insertion mutants were dramatically enhanced by preinoculation growth conditions favoring fimbrial expression. After growth under these conditions, 103 CFU of the fimbriation- proficient strain inoculated intraperitoneally caused no mortality; in sharp contrast, the permanently nonfimbriated insertion mutant resulted in death in 60% of the animals inoculated. Notwithstanding evidence that type 1 fimbriae mediate enterobacterial adherence to mammalian oropharyngeal and bladder mucosae, the results presented here demonstrate that type 1 fimbrial expression can lead to diminution of the number of E. coli organisms within the peritoneum.

Original languageEnglish (US)
Pages (from-to)1667-1673
Number of pages7
JournalInfection and immunity
Issue number5
StatePublished - Jan 1 1993


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