Genotyping of New and Old Proteus mirabilis Isolates from Mansoura Hospitals in Egypt by rpoB Sequence Analysis

Sequence analysis of the RNA polymerase B subunit encoding gene (rpoB) has been proposed as a useful tool for bacterial identification. This method has been implemented to differentiate five well-defined Proteus species: P. mirabilis, P. hauseri, P. penneri, P. vulgaris, and P. myxofaciens. In this study, we evaluated the usefulness of rpoB sequencing for intraspecies discrimination of P. mirabilis. The sequence of rpoB 909 bp region was analyzed in 15 newly isolated strains and 5 of 8 years old isolates from different clinical sources. Three respective groups were obtained. The first group included 13 of the new strains showing similarity with Proteus mirabilis (ATCC 29906) strain. The second group including 3 of the old strains differs from the first group with a divergence of 0.22%. Group 3 contains only a single new strain 33. The sequence of this strain shows differences in the rpoB 909 bp region analyzed from the members of group 1 and the second group by 1.65% and 1.87% divergence respectively. According to our results, genetic differences could be detected within the P. mirabilis species. Therefore much more effort should be made to re-evaluate rpoB method and validate its usefulness as a molecular diagnostic method.