Growth, swarming and production of halo-zone of different proteus mirabilis strains isolated from Jordanian clinical specimens

The growth, swarming and production of halo-zone by six different strains of P. mirabilis were examined on different selective media. Inability of strains to grow on different selective medium commonly showed at 25°C. The swarming did not observe on Baired-Parker stable base agar and cetrimide agar medium at both used temperatures [25 and 37°C]; whereas no swarming observed on desoxycholate citrate lactose agar medium at 25°C and on violet red bile agar medium at 37°C. Both strains [PM4 and PM5] were able to produce hydrogen sulfide [H 2S] at both used temperatures; in contrast, the other two strains [PM2 and PM3] were H 2S negative. But PM1 and PM6 were H 2S positive at 37°C and negative at 25°C. Several compounds inhibit the motility of swarmer cells by disturbing the structural integrity, the activity of flagella or by blocking their ability to move. Those compounds may also inhibit swarming but without affecting growth

Mini-Mu insertions in the tetracycline resistence determinant from proteus mirabilis

The inducible tetracycline resistance determinant isolated from Proteus mirabilis cloned into the plasmid pACYC177 was mutagenized by insertion of a mini-Mu-lac phage in order to define the regions in the cloned sequences encoding the structural and regulatory proteins. Three different types of mutants were obtained: one lost the resistance phenotype and became Lac+; another expressed the resistance at lowerlevels and constitutively; the third was still dependent on induction but showed a lower minimal inhibitory concentration. The mutant phenotypes and the locations of the insertions indicate that the determinant is composed of a repressor gene and a structural gene which are not transcribed divergently as are other known tetracycline determinants isolated from Gram-negative bacteria.