Biochemical identification and characterization of DNA groups within the Proteus vulgaris complex

The prevailing O serogroups among the serologically differentiated clinical Proteus spp. strains in central Poland

In the years 2006–2011, 617 Proteus spp. strains isolated mostly from urine and wounds or other clinical sources were collected in Łódź, Poland, to determine the offensive O serotypes frequently occurring among patients. P. mirabilis exhibited the most intensive swarming growth and was dominating species (86.9%), followed by P. genomospecies, P. vulgaris, and P. penneri. Ninety four per cent strains were recognized as S (smooth) forms. Serological studies (involving ELISA—enzyme-linked immunosorbent assay and Western blotting using native and adsorbed rabbit antisera) enabled classification of 80% S isolates into respective Proteus O serogroups among the 83 ones, described so far. The remaining strains seemed to be serologically unique. Despite the observed big serological variety of Proteus spp. isolates, we found the O78 serogroup recently described in Poland as dominating and identified other widespread serotypes: O3, O6, O10, O11, O27, O28, and O30 reported earlier as predominating also in other countries; O77 and O79 detected lately in Poland; O16, O18, O20, and O50. No unique structural feature of the prevalent O serotypes has been indicated. However, the prevalence of some O serogroups indicates that particular serotypes may be in some ways beneficial to the strains producing these kinds of O antigen.

Structures and serospecificity of threonine-containing O polysaccharides of two clinical isolates belonging to the genus Proteus and their classification into O11 subserogroups

Two clinical isolates from Polish patients, Proteus mirabilis 9B-m and Proteus genomospecies 3J-r, were found to be serologically related to P mirabilis O11. However, serological studies involving ELISA and Western blotting methods, using lipopolysaccharides (LPSs) extracted from the strains as antigens and native or adsorbed rabbit polyclonal O antisera, specific to the studied strains, revealed slight differences in the cross-reactivity and specificity of the two studied Proteus isolates, when compared to P. mirabilis O11. Two different O polysaccharides containing N-(d-galacturonoyl)-l-threonine were isolated from the LPSs of the isolates. Their structures were determined by chemical analysis and NMR spectroscopy and found to be related to the P. mirabilis O11 antigen structure established earlier, the 9B-m structure differing in the absence of the lateral glucose residue and the 3J-r structure in non-stoichiometric O-acetylation of the threonine residue only. Thus, the Proteus O11 serogroup should be divided into two subgroups: O11a, represented by the 9B-m isolate and O11a, b possessing the additional b epitope, containing the lateral residue of glucose and formed by the 3J-r isolate as well as P. mirabilis 25/57 belonging to O11 serogroup so far. O11a is the sixth new serotype found in Proteus spp. strains recently isolated from patients in central Poland.

Significance and Roles of Proteus spp. Bacteria in Natural Environments

Proteus spp. bacteria were first described in 1885 by Gustav Hauser, who had revealed their feature of intensive swarming growth. Currently, the genus is divided into Proteus mirabilis, Proteus vulgaris, Proteus penneri, Proteus hauseri, and three unnamed genomospecies 4, 5, and 6 and consists of 80 O-antigenic serogroups. The bacteria are known to be human opportunistic pathogens, isolated from urine, wounds, and other clinical sources. It is postulated that intestines are a reservoir of these proteolytic organisms. Many wild and domestic animals may be hosts of Proteus spp. bacteria, which are commonly known to play a role of parasites or commensals. However, interesting examples of their symbiotic relationships with higher organisms have also been described. Proteus spp. bacteria present in soil or water habitats are often regarded as indicators of fecal pollution, posing a threat of poisoning when the contaminated water or seafood is consumed. The health risk may also be connected with drug-resistant strains sourcing from intestines. Positive aspects of the bacteria presence in water and soil are connected with exceptional features displayed by autochthonic Proteus spp. strains detected in these environments. These rods acquire various metabolic abilities allowing their adaptation to different environmental conditions, such as high concentrations of heavy metals or toxic substances, which may be exploited as sources of energy and nutrition by the bacteria. The Proteus spp. abilities to tolerate or utilize polluting compounds as well as promote plant growth provide a possibility of employing these microorganisms in bioremediation and environmental protection.

Screening of marine bacteria with bacteriocin-like activities and probiotic potential for ornate spiny lobster (Panulirus ornatus) juveniles

Bacteriocins are ribosomally synthesized antimicrobial peptides, which have been found in diverse bacterial species of terrestrial origins and some from the sea. New bacteriocins with new characteristics, new origins and new applications are likely still awaiting discovery. The present study screened bacteria isolated from marine animals of interest to the aquaculture industry for antimicrobial and bacteriocin-like activities in order to uncover biodiversity of bacteriocin producers, and explore the potential application in aquaculture. In total, 24 of 100 screened isolates showed antimicrobial activities and 7 of these exerted bacteriocin-like activities. Sequencing of 16S rRNA genes identified the isolates as members of the six genera Proteus, Providencia, Klebsiella, Alcaligenes, Bacillus and Enterococcus. In some cases, further analysis of housekeeping genes, rpoB for Proteus and recA for Klebsiella, as well as biochemical tests was necessary for identification to species level, and some of the Proteus isolates may represent novel species. The seven bacteriocinogenic isolates showed a wide antimicrobial spectrum against foodborne and animal pathogens, which opens the way to their potential use as marine drugs and probiotics in food, aquaculture, livestock and clinical settings. As a case study, the protective effect of shortlisted bacteriocinogenic isolates were tested in aquaculture-raised spiny lobster (Panulirus ornatus) juveniles. A single-strain (Bacillus pumilus B3.10.2B) and a three-strain (B. pumilus B3.10.2B, Bacillus cereus D9, Lactobacillus plantarum T13) probiotic preparation were added to the feed of Panulirus ornatus juveniles, which were subsequently challenged with the pathogen Vibrio owensii DY05. Juveniles in the probiotic treatments displayed increased growth and reduced feed conversion rates after 60 days, and increased survival rate after pathogen challenge relative to the control. This study represents the first evidence of bacteriocin production by bacteria associated with lobster, tiger shrimp, snubnose pompano and cobia and the first description of V. owensii as a pathogen in P. ornatus juveniles.

Proteus penneri

Proteus penneri, formerly P. vulgaris biogroup 1, was recognized as a new species in 1982. This species is associated with clinical processes similar to those involving P. mirabilis and P. vulgaris and expresses similar pathogenic determinants. In clinical samples, P. penneri is mainly isolated from urine (50%), wound and soft tissue exudates (25%), and blood cultures (15%), mostly of nosocomial origin. Although P. penneri is easy to identify, it can be misidentified as P. vulgaris by automatic systems that do not include the indol test result in the identification process. This species has a characteristic susceptibility profile, essentially due to the production of the chromosomal inducible beta-lactamase HugA, which presents a high homology (86%) with CumA from P. vulgaris. HugA is inhibited by clavulanic acid and determines resistance to aminopenicillins and first- and second-generation cephalosporins, including cefuroxime, but does not affect cephamycins or carbapenems, and is inhibited by clavulanic acid. HugA is derepressed due to mutational processes in gene regulators, affecting the activity of cefotaxime and, to a much lesser extent, that of ceftazidime and aztreonam. This phenotype resembles the production of an extended spectrum beta-lactamase. Like other Proteus species, P. penneri is resistant to tetracyclines and should be considered resistant to nitrofurantoin.

Rapid detection of isoniazid and rifampin resistance mutations in Mycobacterium tuberculosis complex from cultures or smear-positive sputa by use of molecular beacons

The slow-growing nature of Mycobacterium tuberculosis complex hinders the improvement of turnaround time for phenotypic drug susceptibility testing. We designed a set of molecular beacons for the detection of isoniazid and rifampin resistance mutations in M. tuberculosis complex organisms from cultures or from N-acetyl-l-cysteine-NaOH-treated, smear-positive specimens. The performance of the molecular beacons was characterized by studying a total of 196 clinical isolates (127 drug-resistant isolates and 69 drug-susceptible isolates). For detection of isoniazid resistance, the sensitivity and specificity of the assay were 82.7 and 100%, and the positive predictive value (PPV) and negative predictive value (NPV) at a resistance prevalence of 10% were 100 and 98.11%, respectively. For detection of rifampin resistance, the sensitivity and specificity of the assay were 97.5 and 100%, and the PPV and NPV at a resistance prevalence of 2.0% were 100 and 99.95%, respectively.

Natural antibiotic susceptibility of Proteus spp., with special reference to P. mirabilis and P. penneri strains

The natural susceptibility of 102 Proteus mirabilis and 35 Proteus penneri strains to 71 antibiotics was examined. Minimum inhibitory concentrations (MICs) were determined by applying a microdilution procedure in IsoSensitest broth (for all strains) and cation-adjusted Mueller Hinton broth (for some strains). P. mirabilis and P. penneri were naturally resistant to penicillin G, oxacillin, all tested macrolides, lincosamides, streptogramins, glycopeptides, rifampicin and fusidic acid. Both species were uniformly, naturally sensitive to all tested aminoglycosides, acylureidopenicillins, some cephalosporins, carbapenems, aztreonam, quinolones, sulfamethoxazole and co-trimoxazole. Species-specific differences in natural susceptibility affecting clinical assessment criteria were seen with tetracyclines, several beta-lactams, chloramphenicol and nitrufurantoin. P. mirabilis was naturally resistant to all tested tetracyclines, and was naturally sensitive to all beta-lactams, except penicillin G and oxacillin. Strains of P. penneri were naturally sensitive or of intermediate susceptibility to tetracyclines, and naturally resistant to amoxicillin (but sensitive or of intermediate susceptibility to aminopenicillins in the presence of beta-lactamase inhibitors) and some cephalosporins (i.e. cefaclor, cefazoline, loracarbef, cefuroxime, cefotiam, and cefdinir). P. penneri was less susceptible than P. mirabilis to chloramphenicol; P. mirabilis was less susceptible than P. penneri to nitrofurantoin. Major medium-dependent influences on the MICs were seen with fosfomycin. The present study describes a database concerning the natural antibiotic susceptibility of P. mirabilis and P. penneri strains to a range of antibiotics, which can be applied to validate forthcoming antibiotic susceptibility tests of these bacteria. It was shown that ten of fifteen amoxicillin-sensitive P. mirabilis strains produced beta-lactamases at a low level, supporting the thesis of the presence of a naturally-occurring beta-lactamase in this species. Natural susceptibility patterns are compared with those of a recent study, dealing with natural susceptibilities of species of the P. vulgaris complex.

Characteristics of Massilia timonae and Massilia timonae-like isolates from human patients, with an emended description of the species

The description of Massilia timonae, a nonfermentative aerobic gram-negative rod, was based on a single strain. A subsequent report of a second isolate has been recently published. Phenotypic descriptions of these two strains were based primarily on commercial test kit results. We have identified three additional strains as M. timonae by 16S rRNA sequence analysis and have characterized them phenotypically in parallel with the type strain of M. timonae, CIP 105350, by conventional test methods. A fourth strain, designated M. timonae-like, was also characterized. All four strains were isolated from human patients: two were blood isolates, one was isolated from cerebrospinal fluid, and one was isolated from bone. The four strains and the type strain were quite similar phenotypically. However, in contrast to the original description, the strains were found to be oxidase positive and arginine dihydrolase negative and to have lateral flagella as well as a single polar flagellum. Additionally the strains produced acid oxidatively from some carbohydrates. Other phenotypic characteristics, including cellular fatty acids, agreed with the original description. Based on our emended description, M. timonae and M. timonae-like strains can be differentiated from other aerobic nonfermentative gram-negative rods by conventional biochemical tests combined with cellular fatty acid analysis.