Molecular Characterization of the Genera Proteus , Morganella , and Providencia by Ribotyping

Abstract

The so-called Proteus-Providencia group is constituted at present by three genera and 10 species. Several of the recognized species are common opportunistic pathogens for humans and animals. Different methods based on the study of phenotypic characters have been used in the past with variable levels of efficiency for typing some species for epidemiological purposes. We have determined the rRNA gene restriction patterns (ribotypes) for the type strains of the 10 different species of the genera Proteus,Morganella, and Providencia. Visual inspection of EcoRV- and HincII-digested DNA from the type strains showed remarkably different patterns for both enzymes, butEcoRV provided better differentiation. Both endonucleases were retained to study a large number of wild and collection strains belonging to the different species. Clinical isolates of Proteus mirabilis, Proteus penneri, Morganella morganii, and Providencia heimbachae showed patterns identical or very similar to those of the respective type strains, so that groups of related patterns (ribogroups) were found to correspond to the diverse species. On the contrary, distinct ribogroups were detected within Providencia alcalifaciens (two ribogroups with both enzymes), Providencia rettgeri (four ribogroups with EcoRV and five with HincII),Providencia stuartii (two ribogroups withEcoRV), Providencia rustigianii (two ribogroups with HincII), and Proteus vulgaris (two ribogroups with both enzymes). The pattern shown by the ancientP. vulgaris type strain NCTC 4175 differed considerably from both P. vulgaris ribogroups as well as from the newly proposed type strain ATCC 29905 and from any other strain in this study, thus confirming its atypical nature. Minor differences were frequently observed among patterns of strains belonging to the same ribogroup. These differences were assumed to define ribotypes within each ribogroup. No correlation was observed between ribogroups or ribotypes and biogroups of P. vulgaris, P. alcalifaciens, P. stuartii, and P. rettgeri. Since, not only different species showed different rRNA gene restriction patterns, but also different ribogroups and ribotypes have been found in the majority of the species, ribotyping would be a sensitive method for molecular characterization of clinical isolates belonging to the genera Proteus, Morganella, and Providencia.

Comparative Epidemiology and Resistance Trends of Proteae in Urinary Tract Infections of Inpatients and Outpatients: A 10-Year Retrospective Study

“…The indole-negative P. mirabilis strains are generally more susceptible to the relevant antibiotics than P. vulgaris (and other related species), Morganella spp., and Providencia spp [13,14,17,18,19,24]; however, this difference in resistance rates was not demonstrated in our present study. Gentamicin resistance has remained relatively constant in the surveillance period, while other antibiotics, which are more frequently used in primary care (especially amoxicillin/clavulanic acid, ciprofloxacin, sulfamethoxazole/trimethoprim, and fosfomycin) or are available in oral formulations, resistance levels show a pronounced and statistically significant increase [48].…”

“…Based on the results of this retrospective survey, the most prevalent isolate at our tertiary-care center remains P. mirabilis ; however, a noteworthy increase (~5–7-times higher) was observed in the isolation rate of Morganella and Providencia species in the second half of the study period. Their higher prevalence in hospitalized patients and catheter-associated infections, a slight male dominance (~1.1–1.5-times) and the advanced age (over 65 years of age) of many affected patients is in line with the findings in the literature [13,14,17,18,19,24]. There is great variation in the species-distribution and susceptibilities of urinary tract pathogens in various parts of the globe, and, therefore, continuous and strict surveillance is recommended [40].…”

“…Species of Proteae are widespread in the environment and are normal inhabitants of the gut microbiota, in addition, they are the third most frequent causative agents of UTIs, especially in nosocomial settings [2,3,4,17]. They are characterized by strong urease production from urine (lowering the pH, which leads to tissue damage, scarring, and stone formation, through the composition of struvite and apatite crystals via precipitation of Ca 2+ and Mg 2+ ions), additionally, they possess virulence factors crucial for the pathogenesis of UTIs (IgA protease, hemolysin, cytotoxins, and fimbriae) [13,14,17,18,19]. In contrast to E. coli , Proteae are more frequently isolated in patients with complicated UTIs (i.e., the presence of urinary catheters and functional or anatomical abnormalities) and are frequently associated with pyelonephritis, recurrence and prolonged treatment [20,21,22,23].…”

“…In contrast to E. coli , Proteae are more frequently isolated in patients with complicated UTIs (i.e., the presence of urinary catheters and functional or anatomical abnormalities) and are frequently associated with pyelonephritis, recurrence and prolonged treatment [20,21,22,23]. They are intrinsically resistant to several groups of antibiotics (nitrofurantoin, tetracyclines, and colistin; this intrinsic resistance may be used as a presumptive identification marker for these organisms), they produce various β-lactamases (penicillinases, AmpC-β-lactamases) and have an intrinsic reduced susceptibility to imipenem, making the management of these infections even more difficult [13,14,17,18,19,24]. It is generally accepted that P. mirabilis has the most advantageous resistance trends among the Proteae group, while P. vulgaris and Morganella species have somewhat higher, and Providencia species have the highest rates of resistance to the relevant antibiotics.…”

“…It is generally accepted that P. mirabilis has the most advantageous resistance trends among the Proteae group, while P. vulgaris and Morganella species have somewhat higher, and Providencia species have the highest rates of resistance to the relevant antibiotics. Indeed, these differences are frequently used in routine microbiology laboratories for their phenotypic identification/differentiation [13,14,17,18,19,24].…”