Emergence of a pandrug-resistant VIM-1-producing Providencia stuartii clonal strain causing an outbreak in a Greek intensive care unit

Here we describe an outbreak caused by a pandrug-resistant Providencia stuartii strain involving 15 critically ill patients in a Greek intensive care unit (ICU) during September-November 2011. All isolates harboured the blaVIM-1 gene and a class 1 integron structure of 1913 bp as well as blaSHV-5 and blaTEM-1. Pulsed-field gel electrophoresis (PFGE) demonstrated that isolates from all 15 patients belonged to a single P. stuartii clonal type. As all of the infected patients were hospitalised during overlapping time periods, horizontal intra-ICU transmission was considered as the main route for the dissemination of the outbreak strain. The outbreak ended following reinforcement of infection control measures, including implementation of additional barrier precautions for infected patients.

Textile dye degradation by bacterial consortium and subsequent toxicological analysis of dye and dye metabolites using cytotoxicity, genotoxicity and oxidative stress studies

The present study aims to evaluate Red HE3B degrading potential of developed microbial consortium SDS using two bacterial cultures viz. Providencia sp. SDS (PS) and Pseudomonas aeuroginosa strain BCH (PA) originally isolated from dye contaminated soil. Consortium was found to be much faster for decolorization and degradation of Red HE3B compared to the individual bacterial strain. The intensive metabolic activity of these strains led to 100% decolorization of Red HE3B (50 mg l(-1)) with in 1h. Significant induction of various dye decolorizing enzymes viz. veratryl alcohol oxidase, laccase, azoreductase and DCIP reductase compared to control, point out towards their involvement in overall decolorization and degradation process. Analytical studies like HPLC, FTIR and GC-MS were used to scrutinize the biodegradation process. Toxicological studies before and after microbial treatment was studied with respect to cytotoxicity, genotoxicity, oxidative stress, antioxidant enzyme status, protein oxidation and lipid peroxidation analysis using root cells of Allium cepa. Toxicity analysis with A. cepa signifies that dye Red HE3B exerts oxidative stress and subsequently toxic effect on the root cells where as biodegradation metabolites of the dye are relatively less toxic in nature. Phytotoxicity studies also indicated that microbial treatment favors detoxification of Red HE3B.

Phylogenetic analysis of the genera Proteus, Morganella and Providencia by comparison of rpoB gene sequences of type and clinical strains suggests the reclassification of Proteus myxofaciens in a new genus, Cosenzaea gen. nov., as Cosenzaea myxofaciens comb. nov

Phylogenetic analysis of partial rpoB gene sequences of type and clinical strains belonging to different 16S rRNA gene-fingerprinting ribogroups within 11 species of enterobacteria of the genera Proteus, Morganella and Providencia was performed and allowed the definition of rpoB clades, supported by high bootstrap values and confirmed by ≥2.5 % nucleotide divergence. None of the resulting clades included strains belonging to different species and the majority of the species were confirmed as discrete and homogeneous. However, more than one distinct rpoB clade could be defined among strains belonging to the species Proteus vulgaris (two clades), Providencia alcalifaciens (two clades) and Providencia rettgeri (three clades), suggesting that some strains represent novel species according to the genotypes outlined by rpoB gene sequence analysis. Percentage differences between the rpoB gene sequence of the type strain of Proteus myxofaciens and other members of the same genus (17.3-18.9 %) were similar to those calculated amongst strains of the genus Providencia (16.4-18.7 %), suggesting a genetic distance at the genus-level between Proteus myxofaciens and the rest of the Proteus-Providencia group. Proteus myxofaciens therefore represents a member of a new genus, for which the name Cosenzaea gen. nov., is proposed.

Providencia vermicola sp. nov., isolated from infective juveniles of the entomopathogenic nematode Steinernema thermophilum

In the course of isolating bacteria from infective juveniles of the entomopathogenic nematodeSteinernema thermophilumGanguly & Singh, 2000, three isolates were obtained (OP1T, OP29 and VS3). On the basis of 16S rRNA gene sequence analysis and riboprint patterns, these three strains were identical to each other but distinct from the type strains of the five recognized species of the genusProvidencia. Based on biochemical and genomic analysis and supported by the low (<35 %) DNA–DNA relatedness between strain OP1Tand the type strain of its phylogenetically closest relative,Providencia rettgeri(99·5 % 16S rRNA gene sequence similarity), strain OP1Twas considered to be sufficiently distinct from recognizedProvidenciaspecies to warrant the description of a novel species. The nameProvidencia vermicolasp. nov. is proposed, with OP1T(=DSM 17385T=CIP 108829T) as the type strain.

Metallo-beta-lactamase IMP-1 in Providencia rettgeri from two different hospitals in Japan

In 2002, 495 indole-positive proteae strains were isolated from patients at 60 hospitals in Japan. Nine indole-positive proteae strains had reduced susceptibility to imipenem (MIC > or = 8 microg ml(-1)) and were identified as Providencia rettgeri by BD Phoenix. Eight of the nine Prov. rettgeri isolates were confirmed as metallo-beta-lactamase producers by the double-disc synergy test. All the metallo-beta-lactamases were classified as IMP-1 by PCR and DNA sequence analysis. These bla(IMP-1) genes were encoded in the integron structure on conjugative plasmids. These plasmids could transfer from Prov. rettgeri clinical isolates to Escherichia coli ML4903 at a frequency between 1.5 x 10(-5) and 5.5 x 10(-7). The eight bla(IMP)-positive strains were isolated from two hospitals, and showed two different PFGE patterns, two different integron structures and two different incompatibility groups, which corresponded to the two hospitals. These results strongly suggest the possibility of nosocomial infections by bla(IMP-1)-producing Prov. rettgeri isolates.

Importance of Providencia species as a major cause of travellers' diarrhoea

In this study the importance of Providencia species as a cause of travellers' diarrhoea was examined using a selective medium developed by the authors. Providencia species could easily be distinguished from other enteric pathogens by the colour of the colonies obtained. Nine strains of Providencia alcalifaciens, nine of Providencia rettgeri and five of Providencia stuartii were isolated from 130 specimens, representing a surprisingly high incidence of infection compared with other pathogens isolated on SS agar and TCBS agar. Patients infected with P. rettgeri complained of abdominal pain, as for other Providencia species, but also of vomiting, which is rather characteristic of P. rettgeri infection. To analyse the pathogenicity of these isolates, their invasiveness was examined using Caco-2 cells. Most of the P. rettgeri strains invaded Caco-2 cells. Random amplified polymorphic DNA (RAPD) fingerprinting showed the same profile for two P. rettgeri isolates from individuals travelling in the same tour group. The results show that Providencia species, especially P. rettgeri, might cause diarrhoea, and that these species are important pathogens.

PER-1 production in a urinary isolate of Providencia rettgeri

A Providencia rettgeri strain resistant to extended-spectrum cephalosporins and intermediate to aztreonam was isolated from the urine of a patient hospitalized in the urology clinic of SSK Educational Hospital in Ankara. Clavulanic acid restored the activity of extended-spectrum cephalosporins, suggesting that the strain was harboring an extended-spectrum beta-lactamase. Since the PER-1 enzyme is widespread in Turkey, and had been already detected in a related species such as Proteus mirabilis, the Providencia strain was suspected of harboring a PER-1 enzyme, which was indeed detected by PCR. This is the first description in a P. rettgeri isolate of a PER-1 enzyme which is widespread among Acinetobacter baumanni and Pseudomonas aeruginosa strains in Turkey.

Structure of the O-polysaccharide of Providencia stuartii O4 containing 4-(N-acetyl-L-aspart-4-yl)amino-4,6-dideoxy-D-glucose

The O-polysaccharide of Providencia stuartii O4 was obtained by mild acid degradation of the lipopolysaccharide, and the following structure of the pentasaccharide repeating unit was established: [structure: see text] where D-Qui4N(L-AspAc) is 4-(N-acetyl-L-aspart-4-yl)amino-4,6-dideoxy-D-glucose, which has not been hitherto found in bacterial polysaccharides. Structural studies were performed using sugar and methylation analyses, Smith degradation and NMR spectroscopy, including conventional 2D 1H,1H COSY, TOCSY, NOESY and 1H,13C HSQC experiments as well as COSY and NOESY experiments run in an H(2)O-D(2)O mixture to reveal correlations for NH protons.

Structure of the O-specific polysaccharide of Providencia alcalifaciens O16 containing N-acetylmuramic acid

The O-specific polysaccharide of Providencia alcalifaciens O16 was obtained by mild-acid degradation of the lipopolysaccharide and studied by chemical methods and NMR spectroscopy, including 2D 1H,(1)H COSY, TOCSY, NOESY, and 1H,(13)C HSQC experiments. It was found that the polysaccharide contains N-acetylmuramic acid, which was isolated by solvolysis with trifluoromethanesulfonic acid and identified by the specific optical rotation and NMR spectroscopy. The following structure of the trisaccharide repeating-unit of the polysaccharide was established:

Classification, identification, and clinical significance of Proteus, Providencia, and Morganella

This review presents the current taxonomy of the genera Proteus, Providencia, and Morganella, along with the current methods for the identification of each species within the three genera, incorporating both conventional biochemical and commercial methods. While all of these organisms are ubiquitous in the environment, individual case reports and nosocomial outbreak reports that demonstrate their ability to cause major infectious disease problems are presented. Lastly, anticipated antimicrobial susceptibility patterns are reviewed. Many of these organisms are easily controlled, but the advent of newer and more powerful antimicrobial agents has led to some problems of which laboratorians need to be aware.

Molecular characterization of the genera Proteus, Morganella, and Providencia by ribotyping

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, but EcoRV 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 with EcoRV), Providencia rustigianii (two ribogroups with HincII), and Proteus vulgaris (two ribogroups with both enzymes). The pattern shown by the ancient P. 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.

Clonal structure of Providencia alcalifaciens strains isolated from diarrhoeal stools in São Paulo, Brazil

Clonal analysis based on ribotyping demonstrated that Providencia alcalifaciens strains isolated mainly from diarrhoeal stools in São Paulo, Brazil, were clustered into two main groups. Eleven distinct ribotype patterns were identified with ClAI, EcoRV and MluI restriction endonucleases. P. alcalifaciens strains with invasive properties were of two ribotype patterns that differed from those identified among non-invasive strains. The ribotyping results confirmed that P. alcalifaciens strains associated with diarrhoeal disease in São Paulo represent distinct groups of strains. Although the invasive strains were isolated from different patients over an extended period they were clustered into two genetically related clones, which seemed to be distributed endemically in the population studied.

Identification of Enterobacteriaceae bacteria by direct matrix-assisted laser desorptiom/ionization mass spectrometric analysis of whole cells

Several members of Enterobacteriaceas were analyzed by matrix-assisted laser desorption ionization (MALDI) time-of-flight mass spectrometry (TOFMS). Characteristic mass spectral peaks and patterns were observed in the mass range of 2 to 20 kDa. The mass peaks reported to be reproducibly observed by previous researchers, which were claimed to serve as species/strain-specific biomarkers, are consistently observed in our current study. Despite the high degree of similarity found in the MALDI mass spectra within the enteric bacteria, minor yet notable differences existed to allow their differentiation. Five spectral peaks at m/z 4364, 5380, 6384, 6856, and 9540, generated reproducibly for each genus studied here, are assigned as family-specific biomarkers for the Family Enterobacteriaceae. The mass peaks at m/z 7324, 7724, 9136, and 9253 are assigned as genus-specific biomarkers for Salmonella. Some unique biomarkers characterizing the species and strains of E. coli are also presented.

Invasion of HEp-2 and other eukaryotic cell lines by Providenciae: further evidence supporting the role of Providencia alcalifaciens in bacterial gastroenteritis

Wild-type strains of Providencia species were evaluated for their ability to invade HEp-2 monolayers based upon microscopic and semi-quantitative assays. Of 14 P. alcalifaciens strains tested, 3 (17%) were found to be highly invasive, 4 (22%) moderately invasive, and the remaining 61% weakly or noninvasive. HEp-2 invasion results were confirmed by thin-section electron microscopy. Invasive capabilities of P. alcalifaciens were greater at higher MOIs (100 to 1000) than at lower inocula (<10 MOI). No strain of P. stuartii or P. rettgeri tested invaded HEp-2 cells. Quantitative assays of Triton X-100-lysed, HEp-2-invaded cells indicated that between 0.001% and 0. 013% of the initial bacterial inoculum was gentamicin resistant. Further testing of select strains on various cell lines indicated the efficiency of invasion was Vero > Y1 > INT-407 > HEp-2. Two isolates recovered from a father and son with prolonged diarrhea after returning from Mexico were found to be identical on the basis of biotype, serotype, and genotype. These results provide additional evidence that some P. alcalifaciens strains cause gastroenteritis.

Prevalence of pathogenic role of Morganella-proteus providencia-group of bacteria in human faeces

Speculation in literature that organisms of the Morganella-Proteus-Providencia (MPP) group can cause diarrhoea led to the present studies which investigated their occurrence and pathogenic role in human faeces. Faecal specimens were collected from a total of 307 subjects, 80 of which were from diarrhoea cases and 277 from healthy controls. Ninety-two species of the MPP (24/80 diarrhoea and 68/277 control) were isolated from 30% of all subjects. None of the species of the MPP group was significantly associated with diarrhoea as their isolation rate in the controls matched that of the diarrhoea cases (30% of each group). Additional evidence of apparent non-involvement as de facto causative agents of diarrhoea was in their inability to demonstrate the LT or ST enterotoxin production. Tests for invasiveness by Sereny test was also negative. There was a concurrent isolation of other proven diarrhoeal pathogens, such as Salmonella spp and enteropathogenic Escherichia coli (EPEC), with the MPP spp in all the cases in the diarrhoeal group. MPP spp was never isolated as the sole pathogen in any diarrhoeal case. We therefore found no strong evidence from our study to associate the species of the MPP group with diarrhoeal production.

Bacteremia due to Providencia stuartii: review of 49 episodes

We reviewed cases of Providencia stuartii bacteremia at a large community teaching hospital during a 12-year period (1981 to 1992). None of the infections were hospital-acquired. Of the 49 patients, 47 (96%) came from a nursing home, and 45 (92%) had a long-term indwelling Foley catheter. The urinary tract was definitely proven to be the source of bacteremia in 35 patients (71%) and was the probable source in another 5 patients (11%). Polymicrobial bacteremia occurred in 25 patients (51%). The overall mortality rate during hospitalization was 25%.

Modified MacConkey medium which allows simple and reliable identification of Providencia stuartii

This work describes a modified MacConkey medium (MCP medium) enabling the simple identification of Providencia stuartii, an emerging nosocomial pathogen. A total of 813 strains, belonging to the families Enterobacteriaceae and Pseudomonadaceae, were tested on MCP medium; all P. stuartii strains were phosphatase positive, as were 97.5% of Morganella morganii strains, in contrast with all other tested organisms. A simple discriminating test, such as the ornithine or citrate test, allowed identification of strains of these species. We have also compared the reliabilities of P. stuartii identification by commercial kits (API 20E system) by using a standard MacConkey or MCP medium. Sixteen and three-tenths percent of P. stuartii strains were misidentified by using the former procedure, while with the latter all strains were correctly identified. Finally, the MCP medium was used over a 6-month period in our routine clinical laboratory. Of a total of 1,278 seeded urine samples from elderly patients, we isolated 103 P. stuartii strains which were all correctly identified by coupling MCP medium and the API 20E system. Seventeen and one-half percent of these strains were misidentified when the API 20E system was used in combination with standard MacConkey medium.

Correlation between DNA polymorphism and enzyme polymorphism argues in favour of the delineation of two species within Providencia alcalifaciens

Ribosomal DNA (rDNA) polymorphism was compared to enzyme polymorphism and DNA/DNA hybridization data for the intraspecies differentiation of Providencia alcalifaciens. DNA from 27 strains previously classified into two zymotypes A1 and A2 and discriminated by two levels of DNA/DNA hybridization (delta Tm values of 0 to 1 degree C and 6 to 10 degrees C, respectively) were analysed by Southern blotting for rDNA polymorphism. The ribotypes fell into two ribogroups A1 and A2, which correlated with the corresponding zymotypes. This correlation argues for the proposed creation of two species within P. alcalifaciens.

Numerical analysis of electrophoretic protein patterns of Morganella morganii strains from faeces, wound, urine and other clinical sources

Sixty-five strains of Morganella morganii (mainly of human origin) were characterized by one-dimensional SDS-PAGE of cellular proteins. The strains came from various countries; 13 were from stools (including one from a toucan), 13 from wounds, 11 from urine, five from blood (including one from a snake), five from the respiratory tract (four sputum, one lung), 12 from miscellaneous sources and six from unknown sources. The protein patterns, which contained 45 to 50 discrete bands, were highly reproducible. The patterns of 67 M. morganii cultures plus those of the type strains of seven Proteus and Providencia species were used as the basis for two numerical analyses. In the first, which included all the protein bands, the M. morganii strains formed 21 clusters at the 91% S level. In the second analysis, in which the principal protein bands (in the 31.6-43.2 kDa range) were excluded, the 67 M. morganii cultures formed a single cluster at the 80% S level distinct from the seven Proteus and Providencia reference strains. We conclude that high resolution PAGE combined with computerized analysis of protein patterns provides the basis for typing clinical strains of M. morganii. Reference strains of each of the 21 PAGE types identified are available from NCTC for inclusion in future studies.

Numerical analysis of electrophoretic protein patterns of Providencia stuartii strains from urine, wound and other clinical sources

Eighty-six strains of Providencia stuartii (mainly of human origin) were characterized by one-dimensional SDS-PAGE of cellular proteins. The strains came from various countries; 52 were from urine, 11 from wounds, five from blood (one of these also from urine), four from ear infections, two each from faeces and sputum, one from 'alimentation' and nine from unknown sources. The protein patterns, which contained 45 to 50 discrete bands, were highly reproducible. The patterns of 46 Prov. stuartii strains (selected to represent the full range of protein pattern diversity) plus those of the type strains of the four other Providencia species were used as the basis for two numerical analyses. In the first, which included all the protein bands, the Prov. stuartii strains formed 13 clusters at the 88% S level. In the second analysis, in which the principal protein bands (in the 33.8-40.7 kDa range) were excluded, 45 of the 46 Prov. stuartii strains formed a single cluster at the 82% S level, whilst the four Providencia reference strains remained unclustered. The 40 strains of Prov. stuartii not included in the cluster analysis were assigned to a protein type by calculating their similarity with the strains in the database used for the cluster analysis. We conclude that high resolution PAGE combined with computerized analysis of protein patterns provides the basis for typing clinical strains of Prov. stuartii. Reference strains of each of the 13 PAGE types identified are available from NCTC for inclusion in future studies.

Numerical analysis of electrophoretic protein patterns of Providencia rettgeri strains from human faeces, urine and other specimens

Thirty-one strains of Providencia rettgeri (mainly from humans) were characterized by one-dimensional SDS-PAGE of cellular proteins. The strains came from various countries and comprised 14 from urine, eight from faeces, two from bile (plus one from the liver of a sheep), two from sputum, one from an insect pupa and three the sources of which were unknown. Also included, for reference purposes, were the type strains of the four other Providencia species. The protein patterns, which contained 45-50 discrete bands, were highly reproducible and were used as the basis for two numerical analyses. In the first, which included all the protein bands, the 31 Prov. rettgeri strains formed 13 clusters at the 84% S level. In the second analysis, in which the principal protein bands (in the 33.3-41.3 kD range) were excluded, 29 of the 31 Prov. rettgeri strains formed a single cluster at the 81% S level, whilst the four Providencia reference strains remained unclustered. We conclude that high resolution PAGE combined with computerized analysis of protein patterns provides the basis for typing clinical strains of Prov. rettgeri. Reference strains of each of the 13 PAGE types identified are available from NCTC for inclusion in future studies.

Usefulness of trehalose fermentation and L-glutamic acid decarboxylation for identification of biochemically aberrant Providencia stuartii strains

A total of 849 Providencia isolates were collected during a 4-year period when an increased incidence of nosocomial Providencia stuartii infection was noted in urologic wards. Of these isolates, 630 were identified as P. stuartii, 206 were identified as Providencia rettgeri, and 1 was identified as Providencia alcalifaciens. Twelve inositol-positive isolates from 10 patients (10 strains) resembled P. stuartii in fermenting trehalose but resembled P. rettgeri in fermenting D-arabitol or meso-erythritol or both. The latter traits, however, were not stable in all cases. These aberrant strains were identified as P. stuartii on the basis of their O antigens and DNA hybridization experiments. All isolates were tested for L-glutamic acid decarboxylase activity by a qualitative thin-layer chromatography method. All P. stuartii isolates, including the aberrant ones, were trehalose positive and L-glutamic acid decarboxylase negative. None of the P. rettgeri isolates fermented trehalose, while 99.0% of them and the single P. alcalifaciens strain were L-glutamic acid decarboxylase positive. Thus, trehalose fermentation and L-glutamic acid decarboxylation are more useful for separating P. stuartii from P. rettgeri than are D-arabitol and meso-erythritol fermentation.

Commercial identification systems often fail to identify Providencia stuartii

We tested 145 clinical isolates in an attempt to evaluate some of the most widely used commercial identification systems in Europe in terms of their ability to identify Providencia strains. Two manual miniaturized systems (API 20E and Enterotube II) and three mechanized-automated systems (Cobas-Bact, Sceptor System, and Titertek-Enterobac-Rapid Automated System) were evaluated. Providencia alcalifaciens and Providencia rettgeri strains were correctly identified by all systems in all cases, and in most cases identification was achieved without the aid of supplementary tube tests. By contrast, Providencia stuartii was identified without the aid of supplementary tube tests for only 42.5% (API 20E), 37.5% (Enterotube), 68.7% (Sceptor), and 71.2% (Cobas-Bact) of the isolates. The overall misidentification rates were 16.3, 11.3, 11.3, and 10%, respectively. The Titertek-Enterobac-Rapid Automated System failed to identify only 1 of 80 strains (1.3%) and required supplementary tests in 2 other cases (2.5%). Since four of the multitest systems examined often failed to correctly identify P. stuartii, we conclude that supplementary conventional tube tests should always be used to distinguish this species from the other taxa of the Proteeae tribe.

Numerical analysis of electrophoretic protein patterns of Providencia alcalifaciens strains from human faeces and veterinary specimens

Twenty-five strains of Providencia alcalifaciens from various countries have been characterized by one-dimensional SDS-PAGE of cellular proteins. They comprised 15 from human faeces, one from duck faeces, one from a guinea-pig eye and eight from unknown sources. Also included, for reference purposes, were the type strains of three other Providencia species. The protein patterns, which contained 45-50 discrete bands, were highly reproducible and were used as the basis for two numerical analyses. In the first, in which the principal protein bands (in the 33-40 kD range) were excluded, the 25 Prov. alcalifaciens strains formed, at the 83% S level, a single cluster whilst the three Providencia reference strains remained unclustered. In the second, which included all the protein bands, the 25 Prov. alcalifaciens strains formed 10 clusters at the 85% S level. We conclude that high resolution PAGE combined with computerized analysis of protein patterns provides the basis for typing clinical strains of Prov. alcalifaciens. Reference strains of each of the 10 PAGE types identified are available from NCTC for inclusion in future studies.

Numerical analysis of electrophoretic protein patterns of Providencia rustigianii strains from human diarrhoea and other sources

Twenty strains of Providencia rustigianii (including the type strain of Prov. friedericiana) have been characterized by one-dimensional SDS-PAGE of cellular proteins. They comprised 12 strains (almost exclusively associated with the intestinal tract) from humans, plus eight largely from the intestinal tract of pig, penguin and environmental sources. The protein patterns, which contained 45-50 discrete bands, were highly reproducible and were used as the basis for two numerical analyses. In the first, which included all the protein bands, the 20 Prov. rustigianii strains formed six clusters at the 88% S level. One of these clusters included the type strains of both Prov. friedericiana and Prov. rustigianii, thereby confirming the synonymy of these two species. In the second analysis, the principal protein bands were excluded. At the 86% S level the 20 Prov. rustigianii strains formed a single cluster, whilst a field strain of Morganella morganii and the respective type strains of three other Providencia species remained unclustered. The total protein pattern of the type strain of Prov. alcalifaciens was very similar to that of Prov. rustigianii phenon 3 and the M. morganii field strain, which indicates that careful biochemical characterization may be necessary to ascribe strains to a species before typing by the PAGE technique. Alternatively, a selective analysis of the protein bands may be used to confirm the identity of the strains, as shown in this study.

Speciation, serotyping, antimicrobial sensitivity and plasmid content of Proteeae from the environment of calf-rearing units in South West England

A survey was undertaken of the occurrence, serotype, antimicrobial sensitivity and plasmid content of members of the tribe Proteeae in the environment of two calf-rearing units in the county of Avon in South West England. Examples of the following species were found: Proteus mirabilis, Prot. vulgaris, Prot. vulgaris Biogroup 2, Morganella morganii, Providencia stuartii, Prov. alcalifaciens and Prov. rettgeri. A wide range of serotypes was found, many having been previously reported from nosocomial isolates. A total of 15% of isolates carried plasmids; six pairs of isolates were identified which had identical serotypes but different patterns of plasmid carriage. The antimicrobial sensitivity of the isolates was generally similar to isolates of Proteeae from humans. Although no truly aminoglycoside-resistant isolates were found, some isolates of Prov. stuartii and Prov. rettgeri had MIC's higher than the other isolates to gentamicin and netilmicin, suggesting the presence of low levels of the enzyme AAC 2'. The study demonstrates that there is a considerable diversity of species and types of Proteeae associated with calves and their environment. It seems likely that a potential cause of colonization of the human gut by Proteeae is the consumption of meat.

Lipopolysaccharide of Providencia rettgeri. Chemical studies and taxonomical implications

The chemical constitutional analysis of the lipopolysaccharide (LPS) isolated from Providencia rettgeri was carried out. Polyacrylamide gel electrophoresis using sodium dodecylsulfate or sodium deoxycholate showed that the lipopolysaccharide mostly consisted of short sugar chains. The lipid A was precipitated out after mild acid hydrolysis of LPS. From the supernatant degraded polysaccharide and unsubstituted core fractions were isolated. Compositional analysis of the core material revealed the presence of galacturonic acid, galactose, glucose, glucosamine, L-glycero-D-manno-heptose, 3-deoxy-D-manno-octulosonic acid, alanine and phosphorus. Methylation analysis of the core material indicated the presence of terminal units of glucose, galacturonic acid and glucosamine. The chemical structure of the lipid A was elucidated. It constitutes a beta-1,6-glucosamine disaccharide substituted on either side by ester and glycosidically-bond phosphate residues. The ester-bound phosphate was found to be substituted by a 4-amino-4-deoxy-L-arabinosyl residue. The amino groups of the backbone disaccharide are N-acylated by 3-O-(14:0)14:0 and 3-O-14:0. Two hydroxyl groups of the disaccharide are esterified by 3-O-(14:0)14:0 and 3-O-14:0. The taxonomical importance of these structural details will be discussed.

A simple chromogenic test for rapid screening of Proteus and Providencia bacteria

A rapid test for detection of p-nitrophenylalanine ammonia-lyase is described. The test is performed by suspending a loopful of bacteria in 0.5 ml of a buffered 1 mM solution of p-nitro-DL-phenylalanine (PNPA). The enzymatic activity is revealed by the formation of a yellow colour after 2 hours of incubation at 35 degrees C. Out of 285 strains of different enterobacteria species positive results were shown only by 75 Proteus and Providence strains. Thus, the PNPA test can be useful for rapid screening of these enterobacteria.

[Electrophoretic polymorphism of lactate, malate and glutamate dehydrogenases, acid phosphatase and esterases of Providencia alcalifaciens, P. stuartii and P. rustigianii]

The polymorphism of glutamate, lactate and malate dehydrogenases, of acid phosphatase and of esterases of 27 strains of Providencia alcalifaciens, 35 strains of P. stuartii and 17 strains of P. rustigianii was investigated by conventional electrophoresis in polyacrylamide agarose gel and by isoelectric focusing in thin-layer polyacrylamide gel. For each enzyme analysed, the three species were characterized by a distinct electrophoretic pattern. The number of allozymes detected by conventional electrophoresis was greater than that detected by isoelectric focusing. The use of these two techniques in parallel led to improved detection of polymorphism of esterase alpha beta from P. alcalifaciens. A two-dimensional profile obtained by plotting isoelectric points against electrophoretic mobilities for malate dehydrogenase, acid phosphatase and beta-A esterase showed a molecular relationship between the diverse allozymes and demonstrated their taxonomic values. Polymorphism varied considerably according to the enzyme and species analysed and was correlated with DNA heterogeneity. The strains of P. alcalifaciens exhibited the greatest enzyme polymorphism and were classified into two main zymotypes reflecting genetic divergence within this species, whereas the strains of P. stuartii were electrophoretically less variable.

Characterization of endemic Providencia stuartii isolates from patients with urinary devices

Providencia stuartii has emerged as a significant nosocomial urinary tract pathogen. An increase in the number of Providencia isolates from urine cultures prompted an investigation into the possibility of an outbreak due to this organism. A high proportion of patients studied had urinary devices. Four wards were screened at two time periods to ascertain the prevalence of Providencia stuartii in urine cultures. Biotype, serotype, antibiogram and plasmid content were determined for each Providencia isolate. Of 129 patients initially sampled 22.5% were found to harbor Providencia stuartii. Biotyping, serotyping and antibiograms indicated an epidemic strain was not present. Similar results were obtained when the wards were screened a second time, with 25.4% of urine cultures found to contain Providencia stuartii. By plasmid analysis the isolates could be grouped into one of ten profiles. A correlation could be made between urease activity and the presence of a large plasmid. No association however could be made between a particular plasmid profile and antibiogram. The data indicate that an epidemic strain of Providencia stuartii was not present. The source(s) of the endemic Providencia stuartii strains remain unknown.

Cryptic plasmids in hospital isolates of Providencia stuarti

The distribution of cryptic plasmids among 123 isolates of Providencia stuarti from a hospital ward during a prospective epidemiological study is reported. Two closely related stable plasmids (34 Kb and 36 Kb) were identified by restriction endonuclease digest analysis of plasmid DNA. One or other of these cryptic plasmids was carried by 40 isolates, the remainder were plasmid-free. A higher proportion of one cryptic plasmid (CPT-A) was found in environmental isolates than in isolates from patients. The serotype of all isolates of P. stuarti was O63 and they were epidemiologically related. Two of the eight patients colonised by P. stuarti carried all three possible variants: plasmid-free (PFI) strains or strains containing cryptic plasmid A (CPT-A) or cryptic plasmid B (CPT-B). The epidemiological significance of these results is discussed.

[Serological passage of bacteria of the genus Providencia isolated from patients with wound, urological and intestinal infections]

A total of 395 Providencia strains isolated from patients and the environment were studied. Their differentiation by O and H antigens revealed that these strains belonged to 36 serological groups and contained 26 varieties of the flagellar antigen. In accordance with the combinations of O and H antigens, 59 serological variants were found among the Providencia strains. 33 new, formerly unknown serovars and 2 flagellar antigens were added to the existing antigenic and diagnostic scheme of Providencia. Most of the strains isolated from patients with surgical complications and burns were found to belong to P. stuartii, serovars O44: H4 and O4: H4, and from patients with acute intestinal diseases, to P. alcalifaciens, serovars O2: H26 and O50: H33.

Providencia rustigianii: a new species in the family Enterobacteriaceae formerly known as Providencia alcalifaciens biogroup 3

The name Providencia rustigianii sp. nov. is proposed for a group of organisms previously known as Providencia alcalifaciens biogroup 3. By DNA hybridization, strains of P. rustigianii were 81 to 99% related to each other at 60 degrees C, but only 44 to 49% related to P. alcalifaciens biogroups 1 and 2 and 26 to 33% related to Providencia stuartii. P. rustigianii could be differentiated from P. alcalifaciens and P. stuartii by simple biochemical tests. P. rustigianii produced acid from D-galactose but not from trehalose; P. stuartii produced acid from both; and P. alcalifaciens produced acid from neither. P. rustigianii could be distinguished from Providencia rettgeri (formerly Proteus rettgeri) by urea hydrolysis and acid production from D-arabitol; P. rustigianii was negative for these two tests, but P. rettgeri was positive. Strains of P. rustiganii were 32 to 34% related to strains of P. rettgeri. Three of the 11 strains of P. rustigianii were isolated from stools, but the sources of the other isolates are unknown. Three strains (27%) were sensitive to colistin, and 82 to 100% were sensitive to ampicillin, carbenicillin, cephalothin, gentamicin, kanamycin, nalidixic acid, streptomycin, and tetracycline. Strain ATCC 33673 (CDC no. 0132-68) is the type strain for this species.

Comparative in vitro activity of semisynthetic penicillins against Proteeae

The in vitro susceptibilities of 181 isolates of precisely identified Proteeae species to five semisynthetic penicillins were determined with low and high inocula. Significant differences in susceptibility patterns among various Proteeae species to the penicillins examined were demonstrated. Providencia stuartii was clearly distinguished from Providencia alcalifaciens by its greater resistance to the antibiotics tested.

A numerical taxonomic study of the genus Shigella

One hundred and two strains representing four species of the genus Shigella and sixty-four strains representing fourteen other genera of the family Enterobacteriaceae were tested for 192 characters based on their morphology, biochemistry and physiology. The data were subjected to a number of numerical analyses. The results (confirmed by the use of overlap statistics) showed that four phenons can be distinguished within the genus shigella. These correspond with the species S. dysenteriae. S. flexneri, S. boydii and S. sonnei. Of the other bacteria studied the Alkalescens-Dispar group was most closely related to the genus Shigella and the need for this group to be studied further is noted. The importance of using computer-based matrices for the routine identification of strains of Shigella and other enterobacteria is discussed. Strains of the genus Providencia clustered separately from the shigellae. Three distinct species were evident within this genus: P. stuartii, O. alcalifaciens and a new Providencia species. The latter can be equated with the 'BG3' group in the DNA-DNA hybridization studies of Brenner et al. (1978).

Antibiotic resistance in Providencia stuartii isolated in hospitals

A total of 238 isolates of Providencia stuartii obtained from infected patients in six Dublin hospitals were grouped by using serological and bacteriocin typing methods and tested for sensitivity to a number of antimicrobial agents. Most isolates were resistant to several of these agents. Resistance to tetracycline, resistance to penicillin, resistance to polymyxin, and probably resistance to nitrofurantoin was intrinsic. Plasmid screening coupled with resistance transfer studies showed that both chromosome-encoded and plasmid-coded resistance mechanisms were clinically important. Ampicillin resistance was both chromosomally and plasmid encoded, whereas resistance to kanamycin and resistance to carbenicillin were exclusively plasmid encoded. Gentamicin resistance was more common than kanamycin resistance, and although gentamicin-resistant strains contained aminoglycoside acetyltransferase activity, no association could be demonstrated with plasmid deoxyribonucleic acid in the strains tested. Unlike minimal inhibitory concentrations for kanamycin, minimal inhibitory concentrations for gentamicin varied over a wide range. P. stuartii isolated obtained from several different countries were tested for comparison. As a group, these strains were less resistant, but they did exhibit similar resistance properties.

Three episodes of nosocomial urinary tract infections caused by one O-serotype of Providencia stuartii

The results of O-serotyping Providencia stuartii isolates in a general hospital showed that 43 isolates were the same serotype (063) and were from 15 patients located in 1 or 2 adjacent wards. On retrospective examination it was found that the series of infections occurred during a 9-month period and could be separated into 3 episodes, involving 7, 6 and 2 patients. All patients who acquired the Providencia stuartii 063 strain were catheterized. The introduction of the strain into the hospital was attributed to a patient catheterized before admission from an institution in which the 063 strain had been identified previously. Antibiotic irrigation was not successful in eliminating Providencia stuartii from the urine and the procedure may be a predisposing factor in preferentially selecting strains of this species.

Hemagglutinins and fimbriae of Providencia spp

A series of 25 strains of Providencia spp. produced at least five different patterns of hemagglutination as judged by results from hemagglutination tests in the presence and absence of D-mannose and at least six distinct types of fimbriae as seen from observations with the electron microscope.

Differences among Providencia species in their in vitro susceptibilities to five antibiotics

Significant differences among the three Providencia species (P. alcalifaciens, P. stuartii, and P. rettgeri) in antimicrobial susceptibilities to five antibiotics were shown. P. stuartii was the most resistant of the three species, and P. alcalifaciens was the most susceptible. P. rettgeri was similar to P. stuartii in susceptibilities to cefoxitin, cephalothin, and cefamandole but differed in showing greater susceptibilities to tobramycin and gentamicin. Cefoxitin (16 micrograms/ml) and cefamandole (16 micrograms/ml) inhibited a greater proportion of P. stuartii isolates than did cephalothin, tobramycin, or gentamicin. The susceptibilities of urea-positive isolates of P. stuartii resembled more closely the susceptibilities of urea-negative isolates of this species than those of P. rettgeri isolates, a finding consistent with the recent recommendation for transferring such urea-positive strains to P. stuartii. Among P. stuartii isolates, marked resistance to cefoxitin accompanied by susceptibility to cefamandole was predominantly restricted to isolates of one serotype (O55). The use of isolates that had been serotyped and classified according to recent proposals for taxonomic changes in the Proteeae provided for clearer demonstration of species differences in susceptibility.

[Serotyping of bacteria of the genus Providencia using the indirect hemagglutination test and the indirect hemagglutination inhibition test]

The experiments with the collection of strains and diagnostic sera available in the USSR confirmed the data contained in the literature on the good prospects of using the indirect hemagglutination test for the serotyping of bacteria belonging to the genus Providencia. Certain differences were observed in cross reactions, revealed by the indirect hemagglutination test and by agglutination: the interrelations of serogroups O14 and O25, O23 and O25, O23 and O29, O29 and O45, O37 and O49, determined by means of the indirect hemagglutination test, could not be detected in the same sera by the slide and tube agglutination tests. For the first time the usefulness of aqueous-saline extracts of agar cultures in the indirect hemagglutination inhibition test to specify more precisely the interrelations between individual bacterial serogroups of the genus Providencia has been shown.

Nosocomial multiply resistant Providencia stuartii: a long-term outbreak with multiple biotypes and serotypes at one hospital

A long-term outbreak of urinary tract-associated multiply resistant Providencia stuartii occurred in a large medical facility that included a 513-bed chronic care unit. The unique characteristics of this outbreak were that from within a single medical facility, P. stuartii with multiple serotypes, biotypes, and antibiograms could be identified. The organisms isolated had five different biotypes, seven different antibiograms, and two major serotypes. All of the organisms were susceptible to amikacin, cefamandole, and cefoxitin. Application of standard infection control measures impeded the spread of this outbreak, and it slowly terminated 16 months later.

O-serotyping Providencia alcalifaciens

The O-serotyping scheme for Providencia was tested on Providencia alcalifaciens isolates collected mostly from two hospitals. The specificites of the somatic (O) antigens of P. alcalifaciens were found to be different from those of Providencia stuartii, and separation of the Providencia typing scheme to allow separate typing of each species led to more efficient typing. All but 4 of 86 isolates were typable. Eighteen serotypes occurred among 53 typable isolates obtained from a pediatric hospital, and 11 occurred among 19 isolates from a general hospital. Thirty-two percent of the isolates from the pediatric hospital belonged to serotype O3, the most frequently isolated and most widely distributed type. The use of the serotyping scheme for P. alcalifaciens is advocated for further studies to examine strains of the species for enteropathogenic types.

Application of O-serotyping in a study of Providencia rettgeri (Proteus rettgeri) isolated from human and nonhuman sources

A somatic (O) antigen serotyping scheme for Providencia rettgeri (Proteus rettgeri) was modified to exclude O-type strains recently reclassified as urea-positive Providencia stuartii and was extended to include new serotypes to provide for serotyping on the basis of 93 O-antigens. Isolates from two hospitals, five public health laboratories, and nonhuman sources (polluted water and frogs) were serotyped. The 112 isolates collected from a large general hospital over a 99-month period were distributed among 42 O-serotypes. No serotype showed significant predominance that would suggest the occurrence of human strains that are more prone than others to cause human infections, but in an institution experiencing cross-infection, 11 of the 22 (50%) isolates belonged to one serotype. The 54 isolates from the five public health laboratories belonged to 33 serotypes, 15 of which were found also among hospital isolates. All but 5 of 99 frog isolates were typable, and the 94 typable isolates were separated into 25 serotypes. Each of the four isolates from polluted water samples was of a different serotype. Sixteen of the serotypes found in frogs and three found in water were also identified among human isolates.

O serotyping of Providencia stuartii isolates collected from twelve hospitals

A collection of 829 isolates of Providencia stuartii, mostly from urological specimens of patients in 12 hospitals, were O serotyped. Hospitals varied in serotype distribution, but most isolates (97%) fell into one or another of 14 O types of P. stuartii. One type (O63) was found in 10 hospitals, and six types (O4, O17, O25, O52, O55, O56) were found in 5 or more hospitals. These seven types were more common than others and included 753 (91%) of the isolates. Only four isolates agglutinated in Providencia alcalifaciens antisera and, for increased efficiency in serotyping, it is recommended that separate schemes be employed for P. stuartii and P. alcalifaciens. Strains endemic in different hospitals may differ in serotype and give rise to nosocomial infections that are clinically recognizable when infections occur in obvious clusters. Nosocomial infections occurring in low frequency among patients not located close to each other in the hospital may be detected with the aid of serotyping.