Antigenic and Structural Properties of the Lipopolysaccharide of the Uropathogenic Proteus mirabilis Dm55 Strain Classified to a New O85 Proteus Serogroup.

The aim of the study was the serological and structural characterization of the lipopolysaccharide (LPS) O antigen from P. mirabilis Dm55 coming from the urine of a patient from Lodz. The Dm55 LPS was recognized in ELISA only by the O54 antiserum, suggesting a serological distinction of the Dm55 O antigen from all the 84 Proteus LPS serotypes described. The obtained polyclonal rabbit serum against P. mirabilis Dm55 reacted in ELISA and Western blotting with a few LPSs (including O54), but the reactions were weaker than those observed in the homologous system. The LPS of P. mirabilis Dm55 was subjected to mild acid hydrolysis, and the obtained high-molecular-mass O polysaccharide was chemically studied using sugar and methylation analyses, mass spectrometry, and 1H and 13C NMR spectroscopy, including 1H,1H NOESY, and 1H,13C HMBC experiments. The Dm55 O unit is a branched three-saccharide, and its linear fragment contains α-GalpNAc and ß-Galp, whereas α-GlcpNAc occupies a terminal position. The Dm55 OPS shares a disaccharide epitope with the Proteus O54 antigen. Due to the structural differences of the studied O antigen from the other described Proteus O polysaccharides, we propose to classify the P. mirabilis Dm55 strain to a new Proteus O85 serogroup.

Immunochemical studies and gene cluster relationships of closely related O-antigens of Aeromonas hydrophila Pt679, Aeromonas popoffii A4, and Aeromonas sobria K928 strains classified into the PGO1 serogroup dominant in Polish aquaculture of carp and rainbow trout.

The present study included three Aeromonas sp. strains isolated from fish tissues during Motile Aeromonas Infection/Motile Aeromonas Septicaemia disease outbreaks on commercial farms, i.e.: Aeromonas hydrophila Pt679 obtained from rainbow trout as well as Aeromonas popoffii A4 (formerly Aeromonas encheleia) and Aeromonas sobria K928 both isolated from carp, which were classified into the new provisional PGO1 serogroup prevailing among aeromonads in Polish aquaculture. The structure of the O-specific polysaccharides of A4 and K928 has been previously established. Here, immunochemical studies of the O-specific polysaccharide of A. hydrophila Pt679 were undertaken. The O-specific polysaccharide was obtained from the lipopolysaccharide of A. hydrophila Pt679 after mild acid hydrolysis and separation by gel-permeation chromatography. The high-molecular-mass fraction was studied using chemical methods and 1H and 13C NMR spectroscopy, including 1H,1H NOESY, and 1H,13C HMBC experiments. The following structure of the branched repeating unit of the O-polysaccharide from A. hydrophila Pt679 was determined: [Formula: see text] The studies indicated that O-polysaccharides from A. hydrophila Pt679, A. popoffii A4 and A. sobria K928 share similarities but they also contain unique characteristics. Western blotting and an enzyme-linked immunosorbent assay revealed that the cross-reactivity of the related O-antigens is caused by the occurrence of common structural elements, whereas additional epitopes define the specificity of the O-serotypes. For genetic relationship studies, the O-antigen gene cluster was characterized in the genome of the A. hydrophila Pt679 strain and compared with the corresponding sequences of A. popoffii A4 and A. sobria K928 and with sequences available in the databases. The composition of the regions was found to be consistent with the O-antigen structures of Aeromonas strains classified into the same PGO1 serogroup.

Personalized prediction of the secondary oocytes number after ovarian stimulation: A machine learning model based on clinical and genetic data.

Controlled ovarian stimulation is tailored to the patient based on clinical parameters but estimating the number of retrieved metaphase II (MII) oocytes is a challenge. Here, we have developed a model that takes advantage of the patient's genetic and clinical characteristics simultaneously for predicting the stimulation outcome. Sequence variants in reproduction-related genes identified by next-generation sequencing were matched to groups of various MII oocyte counts using ranking, correspondence analysis, and self-organizing map methods. The gradient boosting machine technique was used to train models on a clinical dataset of 8,574 or a clinical-genetic dataset of 516 ovarian stimulations. The clinical-genetic model predicted the number of MII oocytes better than that based on clinical data. Anti-Müllerian hormone level and antral follicle count were the two most important predictors while a genetic feature consisting of sequence variants in the GDF9, LHCGR, FSHB, ESR1, and ESR2 genes was the third. The combined contribution of genetic features important for the prediction was over one-third of that revealed for anti-Müllerian hormone. Predictions of our clinical-genetic model accurately matched individuals' actual outcomes preventing over- or underestimation. The genetic data upgrades the personalized prediction of ovarian stimulation outcomes, thus improving the in vitro fertilization procedure.

Structural and Serological Characterization of the O Antigen of Proteus mirabilis Clinical Isolates Classified into a New Proteus Serogroup, O84.

Two closely related Proteus mirabilis smooth strains, Kr1 and Ks20, were isolated from wound and skin samples, respectively, of two infected patients in central Poland. Serological tests, using the rabbit Kr1-specific antiserum, revealed that both strains presented the same O serotype. Their O antigens are unique among the Proteus O serotypes, which had been described earlier, as they were not recognized in an enzyme-linked immunosorbent assay (ELISA) by a set of Proteus O1-O83 antisera. Additionally, the Kr1 antiserum did not react with O1-O83 lipopolysaccharides (LPSs). The O-specific polysaccharide (OPS, O antigen) of P. mirabilis Kr1 was obtained via the mild acid degradation of the LPSs, and its structure was established via a chemical analysis and one- and two-dimensional 1H and 13C nuclear magnetic resonance (NMR) spectroscopy applied to both initial and O-deacetylated polysaccharides, where most ß-2-acetamido-2-deoxyglucose (N-acetylglucosamine) (GlcNAc) residues are non-stoichiometrically O-acetylated at positions 3, 4, and 6 or 3 and 6, and a minority of α-GlcNAc residues are 6-O-acetylated. Based on the serological features and chemical data, P. mirabilis Kr1 and Ks20 were proposed as candidates to a new successive O-serogroup in the genus Proteus, O84, which is another example of new Proteus O serotypes identified lately among serologically differentiated Proteus bacilli infecting patients in central Poland.

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 Lódz, 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.

Structural Studies of the Lipopolysaccharide of Aeromonas veronii bv. sobria Strain K133 Which Represents New Provisional Serogroup PGO1 Prevailing among Mesophilic Aeromonads on Polish Fish Farms.

In the present work, we performed immunochemical studies of LPS, especially the O-specific polysaccharide (O-PS) of Aeromonas veronii bv. sobria strain K133, which was isolated from the kidney of carp (Cyprinus carpio L.) during an outbreak of motile aeromonad infection/motile aeromonad septicemia (MAI/MAS) on a Polish fish farm. The structural characterization of the O-PS, which was obtained by mild acid degradation of the LPS, was performed with chemical methods, MALDI-TOF mass spectrometry, and 1H and 13C NMR spectroscopy. It was revealed that the O-PS has a unique composition of a linear tetrasaccharide repeating unit and contains a rarely occurring sugar 2,4-diamino-2,4,6-trideoxy-D-glucose (bacillosamine), which may determine the specificity of the serogroup. Western blotting and ELISA confirmed that A. veronii bv. sobria strain K133 belongs to the new serogroup PGO1, which is one of the most commonly represented immunotypes among carp and trout isolates of Aeromonas sp. in Polish aquacultures. Considering the increase in the MAI/MAS incidences and their impact on freshwater species, also with economic importance, and in the absence of an effective immunoprophylaxis, studies of the Aeromonas O-antigens are relevant in the light of epidemiological data and monitoring emergent pathogens representing unknown antigenic variants and serotypes.

Structural and serological characterization of the O82 antigen of a Proteus mirabilis strain isolated from a patient in Poland.

P. mirabilis strains Kro 45 and Kwy 46 were isolated from the pus and the muscular fluid, respectively, of a hospitalized 61-year-old female in Lódz, Poland. Both strains demonstrated a good swarming ability on a solid medium, and the Dienes test for differentiation of swarming strains indicated their identity. The strains were serologically identical and did not belong to any of the known Proteus O1-O81 serogroups. In this work, we studied the O-specific polysaccharide (O antigen) of P. mirabilis Kwy46, which defines the immunospecificity of the strain. The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide, and the following structure of its oligosaccharide repeat (O-unit) was established by sugar analysis along with 1D and 2D 1H and 13C NMR spectroscopy: where (S)-lac indicates an (S)-1-carboxyethyl group [an (S)-lactic acid residue], which forms an ether with a GlcNAc residue (so called glycolactilic acid). This structure is unique among Proteus O-polysaccharides but shares a trisaccharide fragment with that of P. mirabilis O5. Studies of the cross-reactivity between P. mirabilis Kwy 46 O antiserum/lipopolysaccharide and Proteus O1-O81 lipopolysaccharides/O antisera allowed identification of a putative Kwy 46 O-antigen epitope. Based on the data obtained, it is proposed to create a new O82 serogroup within the genus Proteus represented by the studied P. mirabilis isolates.

Structural and Serological Studies of the O6-Related Antigen of Aeromonas veronii bv. sobria Strain K557 Isolated from Cyprinus carpio on a Polish Fish Farm, which Contains L-perosamine (4-amino-4,6-dideoxy-L-mannose), a Unique Sugar Characteristic for Aeromonas Serogroup O6.

Amongst Aeromonas spp. strains that are pathogenic to fish in Polish aquacultures, serogroup O6 was one of the five most commonly identified immunotypes especially among carp isolates. Here, we report immunochemical studies of the lipopolysaccharide (LPS) including the O-specific polysaccharide (O-antigen) of A. veronii bv. sobria strain K557, serogroup O6, isolated from a common carp during an outbreak of motile aeromonad septicemia (MAS) on a Polish fish farm. The O-polysaccharide was obtained by mild acid degradation of the LPS and studied by chemical analyses, mass spectrometry, and 1H and 13C NMR spectroscopy. It was revealed that the O-antigen was composed of two O-polysaccharides, both containing a unique sugar 4-amino-4,6-dideoxy-L-mannose (N-acetyl-L-perosamine, L-Rhap4NAc). The following structures of the O-polysaccharides (O-PS 1 and O-PS 2) were established.

Chemical characterization and serological properties of a unique O-polysaccharide of the Proteus mirabilis Sm 99 clinical strain - Identification of a new, O81, serotype.

The current serological classification scheme of the medically important bacteria from the genus Proteus consists of 80 O serogroups, the last four of which (O77-O80) were created from clinical strains from Lódz, Poland. There are more serologically unique strains isolated from patient that do not fit into the existing scheme, such as Proteus mirabilis strain Sm 99 isolated from urine of a 74-year-old woman in Lódz. Serological investigation involving ELISA and Western blotting failed to classify the Proteus mirabilis strain Sm 99 into any of the 80 Proteus O serogroups. Sugar analysis along with two-dimensional NMR spectroscopy showed that the O-polysaccharide is composed of branched pentasaccharide repeating units containing one residue each of d-Glc, d-GlcNAc, d-GalNAc, d-glucuronic acid, and 4-[(R)-3-hydroxybutanoylamino]-4,6-dideoxy-d-glucose. The chemical and serological data show that the O antigen of P. mirabilis Sm 99 is unique among the known Proteus O antigens. Based on this finding, it is proposed to extend the current serological classification scheme of Proteus by adding a new serogroup, O81, which at present consists of P. mirabilis strain Sm 99 only.

Genetic diversity of the O antigens of Proteus species and the development of a suspension array for molecular serotyping.

Proteus species are well-known opportunistic pathogens frequently associated with skin wound and urinary tract infections in humans and animals. O antigen diversity is important for bacteria to adapt to different hosts and environments, and has been used to identify serotypes of Proteus isolates. At present, 80 Proteus O-serotypes have been reported. Although the O antigen structures of most Proteus serotypes have been identified, the genetic features of these O antigens have not been well characterized. The O antigen gene clusters of Proteus species are located between the cpxA and secB genes. In this study, we identified 55 O antigen gene clusters of different Proteus serotypes. All clusters contain both the wzx and wzy genes and exhibit a high degree of heterogeneity. Potential functions of O antigen-related genes were proposed based on their similarity to genes in available databases. The O antigen gene clusters and structures were compared, and a number of glycosyltransferases were assigned to glycosidic linkages. In addition, an O serotype-specific suspension array was developed for detecting 31 Proteus serotypes frequently isolated from clinical specimens. To our knowledge, this is the first comprehensive report to describe the genetic features of Proteus O antigens and to develop a molecular technique to identify different Proteus serotypes.

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.

Vaccines in prophylaxis of urinary tract infections caused by the bacteria from the genus Proteus.

Urinary tract infections (UTIs) pose a threat especially to women, the individuals with weakened immunity or with abnormalities in the urinary tract as well as to hospitalized and catheterized patients. The bacteria from the genus Proteus, especially P. mirabilis, are important UTI pathogenic factors. They frequently cause chronic, recurrent or severely complicated infections, resulting in the urinary stones production due to urease and other virulence factors. The ability to survive inside the stones and the increasing antibiotic resistance make it difficult to eradicate the bacteria from the urinary tract. A good solution to the problem may be the vaccination which obtained the interest from the surveyed persons, in spite of the antivaccination attitudes visible also in Poland. Currently, there are four vaccines available, composed of killed cells of different uropathogens, including Proteus spp. They are administrated intranassaly or vaginally and require many booster doses. They decrease the probability of reinfection in patients suffering from recurrent UTIs but the mechanisms of the immune response have not been exactly defined. Promising results were obtained in the studies on a mice model concerning the subunit, conjugated vaccines in which various P. mirabilis surface antigens (with the exception of flagellin) were successfully employed. Hitherto, the best results were obtained by the intranasal vaccinations, using MR/P fimbriae antigens with MPL or cholera toxin adjuvants and the antigens expressed in Lactococcus lactis or Salmonella Typhimurium. It led to an increase in the levels of the specific serum and mucosal antibodies resulting in the protection against P. mirabilis UTIs.

Immunochemical characterization of the O antigens of two Proteus strains, O8-related antigen of Proteus mirabilis 12 B-r and O2-related antigen of Proteus genomospecies 5/6 12 B-k, infecting a hospitalized patient in Poland.

A hospitalized 73-year-old woman was infected with a Proteus mirabilis strain, 12 B-r, isolated from the place of injection of a blood catheter. Another strain, 12 B-k, recognized as Proteus genomospecies 5 or 6, was isolated from the patient's faeces, which was an example of a nosocomial infection rather than an auto-infection. Serological investigation using ELISA and Western blotting showed that strain 12 B-k from faeces belonged to the Proteus O2 serogroup. Strain 12 B-r from the wound displayed cross-reactions with several Proteus O serogroups due to common epitopes on the core or O-specific parts of the lipopolysaccharide. Studies of the isolated 12 B-r O-specific polysaccharide by NMR spectroscopy revealed its close structural similarity to that of Proteus O8. The only difference in 12 B-r was the presence of an additional GlcNAc-linked phosphoethanolamine residue, which creates a putative epitope responsible for the cross-reactivity with Pt. mirabilis O16. The new O-antigen form could appear as a result of adaptation of the bacterium to a changing environment. On the basis of the data obtained, we suggest division of the O8 serogroup into two subgroups: O8a for strains of various Proteus species that have been previously classified into the O8 serogroup, and O8a,b for Pt. mirabilis 12 B-r, where 'a' is a common epitope and 'b' is a phosphoethanolamine-associated epitope. These findings further confirm serological and structural heterogeneity of O antigens of Proteus strains isolated lately from patients in 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.

Halorhabdus rudnickae sp. nov., a halophilic archaeon isolated from a salt mine borehole in Poland.

Two halophilic archaea, designated strains WSM-64(T) and WSM-66, were isolated from a sample taken from a borehole in the currently unexploited Barycz mining area belonging to the "Wieliczka" Salt Mine Company, in Poland. Strains are red pigmented and form non-motile cocci that stain Gram-negative. Strains WSM-64(T) and WSM-66 showed optimum growth at 40 °C, in 20% NaCl and at pH 6.5-7.5. The strains were facultative anaerobes. The major polar lipids of the two strains were phosphatidylglycerol (PG2), phosphatidylglycerol phosphate methyl ester (PGP-Me) and sulfated diglycosyl diether (S-DGD). Menaquinone MK-8 was the major respiratory quinone. The DNA G+C content of strain WSM-64(T) was 61.2 mol% by HPLC method; 61.0 mol% by genome sequencing. Analysis of the almost complete 16S rRNA gene sequence indicated that the strains WSM-64(T) and WSM-66 (99.7% identity) represented a member of the genus Halorhabdus in the family Halobacteriaceae. Both strains formed a distinct cluster and were most closely related to Halorhabdus tiamatea SARL4B(T) and Halorhabdus utahensis AX-2(T) (DSM 12940(T)) (95.4% and 95.6%, respectively). ANI values of WSM-64(T) with the closest relative type strains were <78.5%. Based on 16S rRNA gene sequence and whole genome analyses, physiological and biochemical characteristics we describe a new species represented by strain WSM-64(T) (=DSM 29498(T) =CECT 8673(T)) for which we propose the name Halorhabdus rudnickae sp. nov.

Classification of a Proteus penneri clinical isolate with a unique O-antigen structure to a new Proteus serogroup, O80.

Proteus penneri is an opportunistic pathogen, which may cause severe diseases, most frequently urinary tract infections in immunocompromised patients. P. penneri Br 114 exhibiting a good swarming growth ability as an S-form strain was isolated from a wound of a patient in Lódz, Poland. Serological studies using ELISA and Western blotting and chemical analyses along with (1)H and (13)C NMR spectroscopy showed that the O-antigen (O-polysaccharide) of this strain is unique among the known Proteus serotypes O1-O79. It possesses a linear pentasaccharide repeating unit containing a partially O-acetylated amide of D-glucuronic acid (GlcA) with L-serine having the following structure: [structure: see text]. These data are a basis for creating a new Proteus serogroup, O80, so far represented by the single Br 114 isolate. The O80 is the 21st O-serogroup containing P. penneri strains and the fourth serogroup based on Proteus spp. clinical isolates from Lódz, Poland.

Structure of a Kdo-containing O polysaccharide representing Proteus O79, a newly described serogroup for some clinical Proteus genomospecies isolates from Poland.

From 41 Proteus genomospecies strains isolated in Poland, seven displayed similar serospecificity in ELISA with intact and adsorbed O antisera as well as in Western blot. The cross-reacting strains were found to belong to Proteus genomospecies 5/6 and classified into a new Proteus serogroup, O79, which seems to be widespread among Proteus genomospecies clinical isolates in Lodz, Poland. The O polysaccharide of the lipopolysaccharide of a representative O79 strain, 11 B-r, was studied by chemical analyses and (1)H and (13)C NMR spectroscopy, and the following structure of the repeating unit was established: →4)-α-D-GlcpNAlaAc-(1→5)-α-Kdop-(2→2)-α-D-Glcp-(1→3)-ß-D-GlcpNAc-(1→ where AlaAc indicates N-acetyl-L-alanyl and Kdo indicates 3-deoxy-D-manno-oct-2-ulosonic acid. The O polysaccharide was unstable under mild acidic conditions and cleaved by acid-labile linkages of Kdo residues to yield a tetrasaccharide with Kdo at the reducing end. The structure established is unique among Proteus O polysaccharides, which is in agreement with the lack of any significant cross-reactivity for the lipopolysaccharide of strain 11 B-r and O antisera against strains of all known Proteus O serogroups and vice versa.

Structure of the alanopine-containing O-polysaccharide and serological cross-reactivity of the lipopolysaccharide of Proteus vulgaris HSC 438 classified into a new Proteus serogroup, O76.

The O-polysaccharide was isolated by mild acid hydrolysis of the lipopolysaccharide of Proteus vulgaris HSC 438, and the following structure was established by chemical methods and one- and two-dimensional (1)H and (13)C NMR spectroscopy: →3)-ß-d-Quip4NAlo-(1→3)-α-d-Galp6Ac-(1→6)-α-d-Glcp-(1→3)-α-l-FucpNAc-(1→3)-ß-d-GlcpNAc-(1→, where d-Qui4N stands for 4-amino-4,6-dideoxy-d-glucose and Alo for N-((S)-1-carboxyethyl)-l-alanine (alanopine); only about half of the Gal residues are O-acetylated. This structure is unique among the Proteus O-polysaccharides, and therefore it is proposed to classify P. vulgaris HSC 438 into a new Proteus serogroup, O76. A serological cross-reactivity of HSC 438 O-antiserum and lipopolysaccharides of some other Proteus serogroups was observed and accounted for by shared epitopes on the O-polysaccharides or lipopolysaccharide core regions, including that associated with d-Qui4NAlo.

Structural and serological studies of the O-polysaccharide of strains from a newly created Proteus O78 serogroup prevalent in Polish patients.

Seven Proteus mirabilis strains from five Polish patients (five isolates from urea and two from feces) appeared to be a bacterial clone widespread in hospitals, most probably due to nosocomial infection and autoinfection. Enzyme-linked immunosorbent assay and Western blot showed that lipopolysaccharides from all strains studied are serologically identical to each other but distinct from Proteus lipopolysaccharides studied earlier and, hence, these strains could not be classified in any of the currently existing 77 Proteus O-serogroups. Accordingly, structural analysis of the O-polysaccharide of a representative strain 1B-m revealed a structure that is typical of Proteus O-antigens but is unique in detail. Based on these data, we propose to classify the strains studied as a new serogroup in the genus Proteus named O78.

Structure and serological properties of the O-antigen of two clinical Proteus mirabilis strains classified into a new Proteus O77 serogroup.

Two Proteus mirabilis strains, 3 B-m and 3 B-k, were isolated from urine and faeces of a hospitalized patient from Lodz, Poland. It was suggested that one strain originated from the other, and the presence of the bacilli in the patient's urinary tract was most probably a consequence of autoinfection. The O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of P. mirabilis 3 B-m and studied by sugar analysis and nuclear magnetic resonance spectroscopy, including two-dimensional rotating frame Overhause effect spectroscopy (ROESY) and 1H,13C heteronuclear single quantum coherence (HSQC) experiments. The following structure of the linear trisaccharide-repeating unit of the O-polysaccharide was established:-->2)-beta-D-Glcp-(1-->3)-alpha-L-6dTalp2Ac-(1-->3)-beta-D-GlcpNAc-(1-->where 6dTal2Ac stands for 2-O-acetyl-6-deoxy-L-talose. It resembles the structure of the O-polysaccharide of Proteus penneri O66, which includes additional lateral residues of 2,3-diacetamido-2,3,6-trideoxy-L-mannose. The lipopolysaccharides from two P. mirabilis strains studied were serologically identical to each other but not to that from any of the existing 76 Proteus O-serogroups. Therefore, the strains were classified into a new O77 serogroup specially created in the genus Proteus. Serological studies using Western blot and enzyme-linked immunosorbent assay with intact and adsorbed O-antisera showed that the P. mirabilis O77 antigen is related to Proteus vulgaris O2 and P. penneri O68 antigens, and a putative disaccharide epitope responsible for the cross-reactivity was revealed.