Type I fimbriation in fimE mutants of Escherichia coli K-12

We reexamined the influence of fimE, also referred to as hyp, on type 1 fimbriation in Escherichia coli K-12. We found that one strain used previously and extensively in the analysis of type 1 fimbriation, strain CSH50, is in fact a fimE mutant; the fimE gene of CSH50 contains a copy of the insertion sequence IS1. Using a recently described allelic exchange procedure, we transferred the fimE::IS1 allele from CSH50 to our present wild-type strain, MG1655. Characterization of this IS1-containing strain (AAEC137), together with another fimE mutant of MG1655 (AAEC143), led to two conclusions about the role of fimE. First, the formation of phase variant colony types, reported widely in strains of E. coli, depends on mutation of fimE, at least in K-12 strain MG1655. Here we showed that this phenomenon reflects the ability of fimE to stimulate the rapid inversion of the fim invertible element from on to off when the bacteria are grown on agar. Second, our analysis of fimE mutants, which is limited to chromosomal constructs, provided no evidence that they are hyperfimbriate. We believe that these results, which are at odds with a previous study using fim-containing multicopy plasmids, reflect differences in gene copy number

Report To The National Academy Of Dental Surgery Infectious Complications Of Articular Prosthesis And Bucco-Dental Infection

One of the major developments in postwar surgery was the replacement of seriously deteriorated articulations with articular prostheses. The practice of mounting articular prostheses is currently met. Nevertheless, the infectious complications at the level of the articular prostheses still raise problems. In effect, the consequences may be disastrous. We can arrive to the point of changing the prosthesis, if that’s possible. In the contrary case, after the retraction of the prosthesis without replacement, a pseudoarthrosis appears and triggers a skeletal deficiency, shrinkage of the limbs and an important physical deterioration (Salvati 1984