Positive and Negative Control of R-Factor Replication in Proteus mirabilis

Positive and negative control of R-factor replication in Proteus mirabilis.

Replication of the 50 and 58 moles per cent guanine plus cytosine (%GC) components of R factor 222 in Proteus mirabilis during growth in the presence and absence of chloramphenicol and after shifting exponential- and stationary-phase cells to conditions which inhibit host protein or deoxyribonucleic acid (DNA) synthesis was examined. Chloramphenicol reduced the growth rate but increased the amo...

R-factor-mediated resistance to tetracycline in Proteus mirabilis.

The expression of R-factor-mediated resistance to tetracycline has been compared in Proteus mirabilis and Escherichia coli. Resistance to a range of concentrations of tetracycline was significantly lower in P. mirabilis than in E. coli in both induced and repressed states. Indirect evidence showed that conditions which result in a marked increase in the level of resistance of P. mirabilis harbo...

Characterization of indole-positive Proteus mirabilis.

Thirteen indole-producing, swarming strains of Proteus were identified by additional biochemical testing as being Proteus mirabilis. These strains were characterized by 40 biochemical tests and by susceptibility testing to 11 antibiotics. All produced ornithine decarboxylase and were susceptible to members of the penicillin-cephalosporin groups of antibiotics. These indole-positive strains are ...

Transduction of R factors in Proteus mirabilis and P. rettgeri.

Phage 34 transduces some R factors to Proteus mirabilis strain 13. These transductants can transmit the R factor by conjugation. Transduction frequencies vary from I x I ~-~/plaque-forming unit (p.f.u.) adsorbed (higher than .chromosomal marker transduction) to 5 x Io-8/p.f.u. adsorbed. Transduced drug resistance markers of other R factors were detected only in the presence of resident$factors ...

Similar anti-Proteus mirabilis titres in P1 positive and P1 negative individuals with rheumatoid arthritis.