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PubMed1995

Beta-D-Glucuronidase activity among prototrophic and auxotrophic variants of Escherichia coli and other Enterobacteriaceae commonly implicated in urinary tract infections.

Glucuronidase (GUD) activity of 102 prototrophic, 91 cysteine-requiring, and 19 thymidine-requiring strains of Escherichia coli was examined using growth from MacConkey, CLED, and enriched brain heart infusion (BHI) agars. After 24 h incubation, GUD activity was detected in 92%-96% of prototrophic strains and a similar proportion of thymidine-requiring strains with most reactions detectable in shorter incubation periods. GUD activity among strains requiring cysteine was significantly less than that found amongst prototrophic strains. The effects of different sources of inocula were evident in the shorter incubation periods. Other strains of the Enterobacteriaceae and oxidative strains frequently implicated in urinary tract infection were also tested. Here, positive reactions were detected among Citrobacter and Enterobacter spp. and a strain of Klebsiella oxytoca, but only after 24 h incubation. GUD activity was not detected among the oxidative strains tested under the same conditions. Although an incubation time of 24 h is necessary to detect activity in a small number of "slow hydrolyzing" E. coli, the increased sensitivity thus attained compromises the specificity of the test for this organism by simultaneously enhancing detection of the enzyme in other enterobacteria.

Bacteriological Techniques↗
PubMedDate not supplied

Diversity of the phosphoenolpyruvate/glucose phosphotransferase system in the Enterobacteriaceae.

The presence of the phosphoenolpyruvate glucose phosphotransferase entry routes was studied in 97 genospecies of Enterobacteriaceae. Phosphoenolpyruvate(PEP)-dependent phosphorylation of alpha-methyl-D-glucoside and 2-deoxyglucose was evidenced in 72 species (group I organisms), suggesting the presence of both the IIGlc (formerly II-BGlc/IIIGlc) and IIMan (formerly II-B/II-AMan) entry routes. Erwinia amylovora, Budvicia aquatica and all species of Leminorella and Proteus (as defined by DNA relatedness studies) showed little or no PEP phosphorylation of 2-deoxyglucose, suggesting the absence of the IIMan entry route (group II organisms). Morganella morganii, Tatumella ptyseos and all species of Xenorhabdus and Providencia (as defined by DNA relatedness studies) showed little or no PEP phosphorylation of alpha-methyl-D-glucoside, suggesting the absence of the IIGlc entry route (group III organisms).

Cell Membrane Permeability↗
PubMedDate not supplied

[Comparative immunological study of glyceraldehydephosphate dehydrogenase in Enterobacteriaceae: contribution of an anti-glyceraldehydephosphate dehydrogenase antiserum of Enterobacter intermedium].

A comparative immunological study of glyceraldehyde-3-phosphate dehydrogenase among Enterobacteriaceae was carried out with an antiserum against Enterobacter intermedium G-3-PDH. Results of immunodiffusion experiments and microcomplement fixation studies showed E. intermedium to be a homogeneous species. The genera Enterobacter and Escherichia were found to be quite heterogeneous.

Complement Fixation Tests↗
PubMedDate not supplied

Extracellular oxidation of D-glucose by some members of the Enterobacteriaceae.

Extracellular D-glucose oxidation by 5 enterobacterial species was studied with the purpose of selecting conditions useful for taxonomic studies. Extracellular production of gluconate from 14C-glucose by bacterial cells was evidenced by DEAE-cellulose paper chromatography. Escherichia coli oxidized glucose only when pyrroloquinoline quinone (PQQ) was added, whereas Serratia marcescens, Yersinia frederiksenii, Erwinia cypripedii and Cedecea lapagei oxidized D-glucose without added PQQ. 2-Deoxyglucose was found to be an excellent non-metabolized analogue of D-glucose in oxidation experiments. D-glucose oxidation was inhibited by KCN, p-chloromercuribenzoic acid and carbonyl cyanide m-chlorophenylhydrazone; and activated by p-benzoquinone. Iodoacetate had no action. Comparative cellulose thin-layer chromatography including 2-ketogluconate and 2,5-diketogluconate (produced by Janthinobacterium lividum) as standards, showed that gluconate was oxidized to 2-ketogluconate by S. marcescens and E. cypripedii, and 2-ketogluconate was oxidized to 2,5-diketogluconate by E. cypripedii. The diversity of D-glucose oxidation products in the Enterobacteriaceae could have some taxonomic applications.

Carbohydrates↗
PubMed1986

O-antigenic chains of lipopolysaccharide prevent binding of antibody molecules to an outer membrane pore protein in Enterobacteriaceae.

The accessibility of outer membrane pore protein PhoE to antibody molecules at the cell surface of intact cells of various Enterobacteriaceae was investigated. Significant antibody binding was observed for only two of the nine strains tested. Analysis of the lipopolysaccharide by sodium dodecyl sulphate gel electrophoresis revealed a clear correlation between the presence of an O-antigenic side chain and the inability to bind PhoE protein-specific antibodies. As mutants that lack the O-antigen chain appeared to have acquired the ability to bind antibody, it must be concluded that the presence of O-antigenic chains of lipopolysaccharide prevents binding of antibodies to PhoE protein at the surface of intact cells. The relevance of this conclusion for the potential use of enterobacterial outer membrane pore proteins as vaccine components is discussed.

Antibodies, Monoclonal↗
PubMedDate not supplied

Palindromic unit highly repetitive DNA sequences exhibit species specificity within Enterobacteriaceae.

Palindromic units (PU, or REP for repetitive extragenic palindrome) constitute a family of DNA sequences of 40 nucleotides which is highly repeated in the genome of Escherichia coli. We analysed the presence of PU sequences in 99 different bacterial genomes by cross-hybridization. When PU sequences were used as a probe, only DNA from Enterobacteriaceae closely related to E. coli exhibited an appreciable hybridization signal: Shigella sonnei, Shigella boydii, Salmonella enteritica serotype Typhimurium, Citrobacter freundii and Levinea malonatica. Furthermore, these bacteria could be divided into two groups which corresponded to a slight difference in their PU sequence: the E. coli group includes S. sonnei and S. boydii; the S. enteritica serotype Typhimurium group includes C. freundii and L. malonatica.

Blotting, Southern↗
PubMed1992

Pyrazinamidase activity in Enterobacteriaceae.

Pyrazinamidase activity was tested in 1,033 strains of 15 different genera of Enterobacteriaceae. The test was performed by a simple method which reveals the production of pyrazionic acid by a heavy bacterial suspension in 0.2 ml of a 0.5% pyrazinecarboxamide solution in Tris-maleate (0.2 M, pH 6) buffer after incubation for 18 h at 37 degrees C. Positivity was revealed by the development of a pink to red color after addition of 2 drops of 1% extemporaneously prepared ferrous ammonium sulphate aqueous solution. Pyrazinamidase activity proved to be a useful characteristic for the differentiation of some species from other enterobacteria devoid of this property. Because of its simplicity, this test is suitable for its introduction into the miniaturized diagnostic kits for the identification of enterobacteria.

Amidohydrolases↗
PubMed2004

The survival of Escherichia coli, faecal coliforms and enterobacteriaceae in general in soil treated with sludge from wastewater treatment plants.

We monitored the effect of the application of treated sludge on the behaviour of enterobacteriaceae (mainly faecal coliforms and especially Escherichia coli) in the soil, and studied their evolution over time after application. Three different sludges were used: two from a municipal sewage plant, one of them had been subjected to anaerobic digestion and heat drying, and the other to anaerobic digestion and mechanical dehydration, and one from a dairy waste treatment to aerobic digestion and gravity thickening. Two types of tests were carried out: type O, in the open air, with no possibility of controlling humidity or temperature; and type L, under laboratory conditions, with controlled temperature and humidity. Sludge tests were also run on unscreened soil previously treated with chemical fertilizer. After 80 days of experimentation the populations of faecal coliforms and E. coli had decreased considerably or were undetectable in assays carried out on the soil/sludge mixtures, under both open-air and laboratory conditions, but that, over the same period, in the mixtures containing chemical fertilizer (calcium ammonium nitrate) there had been a considerable increase in the micro-organism populations studied.

Analysis of Variance↗
PubMed2004

Susceptibility of meropenem and comparators tested against 30,634 Enterobacteriaceae isolated in the MYSTIC Programme (1997-2003).

A total of 30,634 global Enterobacteriaceae isolates collected from the MYSTIC (Meropenem Yearly Surveillance Test Information Collection) Programme were tested using a reference methodology against meropenem and seven other broad-spectrum agents commonly used in the hospital setting (1997-2003). The most active compound was meropenem (99.6% susceptible), followed by imipenem (98.4%), cefepime (94.0%), gentamicin (86.8%), piperacillin/tazobactam (85.8%), ceftazidime (85.0%), ciprofloxacin (84.6%), and tobramycin (84.5%). Continued surveillance of antimicrobial compounds' in vitro activity is necessary to recommend regimens that are likely to be effective in clinical practice.

Anti-Bacterial Agents↗
PubMed2005

Evaluation of a new screen agar plate for detection and presumptive identification of Enterobacteriaceae producing extended-spectrum beta-lactamases.

A new agar screen plate for extended-spectrum beta-lactamase (ESBL) detection was evaluated with 50 clinical isolates of ESBL-producing Enterobacteriaceae species: Enterobacter cloacae (n = 10), Escherichia coli (n = 10), Klebsiella oxytoca (n = 3), Klebsiella pneumoniae (n = 25), and Proteus mirabilis (n = 2). Fecal samples were artificially inoculated with 2 concentrations (25 and 250 colony forming units [CFU]/plate) of the test strains and then applied to the new agar screen plates. By this approach, the new agar formula detected growth that was suggestive of ESBL activity in 44 of 50 (88%) and 50 of 50 (100%) of ESBL strains with 25 and 250 CFU/plate, respectively. A limitation of the agar screen plates was a lack of some specificity. Among 15 strains with resistant phenotypes other than ESBL (K1 producers of K. oxytoca, 6 strains; 9 strains with AmpC phenotype), growth was recorded in 7 (25 CFU/plate) and 11 (250 CFU/plate) of 15 strains. In conclusion, the new agar screen plate is a sensitive and convenient method to directly screen for ESBL organisms in rectal swabs or stool samples, with the potential for incorporation into routine clinical laboratory service.

Agar↗
PubMed2006

Performance in detection and reporting beta-lactam resistance phenotypes in Enterobacteriaceae: a nationwide proficiency study in Italian laboratories.

We evaluated the ability of 60 Italian clinical microbiology laboratories in detecting and reporting beta-lactam resistance phenotypes in Enterobacteriaceae. Laboratories received 5 well-characterized isolates producing extended-spectrum beta-lactamases (ESBLs), 2 hyperproducers of chromosomal enzymes, and 3 quality control strains. The performances in antimicrobial susceptibility testing (AST) were different depending on the species and type of ESBL produced. High rates of very major errors (up to 56%) were observed for ESBL producers when testing cephalosporins and aztreonam, especially in the case of CTX-M-1-producing Escherichia coli and TEM-52-producing Proteus mirabilis. Isolates hyperproducing chromosomal enzymes were erroneously reported as ESBL producers in approximately 20% of cases. Detection of ESBLs is still a problem for clinical microbiology laboratories. Overall, performances in AST appear to be better with Klebsiella spp. producing well-known enzymes (e.g., SHV type) than with strains producing emerging enzymes (e.g., CTX-M type) or organisms not well recognized as ESBL producers (e.g., P. mirabilis).

Enterobacteriaceae↗
PubMed2006

First report of CTX-M-15 and CTX-M-3 beta-lactamases among clinical isolates of Enterobacteriaceae in Béjaia, Algeria.

We assessed the prevalence and phenotypic characteristics of extended-spectrum beta-lactamase producers among 365 clinical isolates of members of the family Enterobacteriaceae recovered from two hospitals in Béjaia, Algeria, between March 2004 and April 2005. Twenty-one strains were resistant to cefotaxime and/or ceftazidime. A double-disk synergy test yielded a positive result in five cases (three Escherichia coli, one Klebsiella pneumoniae and one Enterobacter cloacae). Using polymerase chain reaction and sequencing, the three E. coli isolates and the K. pneumoniae isolate were found to produce extended-spectrum beta-lactamase CTX-M-15 and the E. cloacae isolate produced CTX-M-3. The three CTX-M-15-producing E. coli isolates were not isolated in the same wards, although genotyping by randomly amplified polymorphic DNA analysis revealed that they were clonally related. The bla(CTX-M-15) genes were transferred from E. coli by conjugation, whilst conjugative transfer of bla(CTX-M) genes from K. pneumoniae and E. cloacae was not detectable.

Algeria↗
PubMed2005

Predictive modelling of growth and measurement of enzymatic synthesis and activity by a cocktail of selected Enterobacteriaceae and Aeromonas hydrophila.

The possibility was examined of developing a predictive model that would predict food spoilage by combining microbial growth (increase in cellular number) with extracellular enzymatic activity of a cocktail of five strains of Enterobacteriaceae: Escherichia coli, Enterobacter agglomerans, Klebsiella oxytoca, Klebsiella pneumoniae and Proteus vulgaris and one Aeromonas hydrophila strain. Estimations of growth and enzyme activity were made within a three-dimensional matrix of conditions: temperature 2-20 degrees C, pH value 4.0-7.5 and water activity (a(w)) 0.95-0.995. A mathematical model was constructed which predicted growth based on increases in cell number. However, although notable effects of extracellular lipases and proteases were detected, it was not possible to model enzymatic activity and prepare a combined model because the data did not follow the characteristic profile that would allow curve-fitting. Nevertheless, the model for microbial growth and information relating to enzyme activity will be made freely available in a database on the internet.

Aeromonas hydrophila↗
PubMed2004

Molecular biology of extended-spectrum beta-lactamase-producing Enterobacteriaceae responsible for digestive tract colonization.

Twenty-nine extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae strains (14 Klebsiella pneumoniae, 10 Escherichia coli and five Citrobacter diversus) isolated from April to July 1996 from faecal carriers in a surgical intensive care unit at the university hospital of Casablanca (Morocco) were studied. Plasmid content and DNA macrorestriction polymorphism determined by pulsed-field gel electrophoresis (PFGE) were used to compare the strains. Restriction profiles of total genomic DNAs cleaved by XbaI and compared by PFGE revealed nine, four and two clones in K. pneumoniae, E. coli and C. diversus, respectively. Plasmid profile analysis of ESBL-producing strains of K. pneumoniae showed that only seven of 14 isolates had a plasmid; four different plasmid profiles were observed. Three different plasmid profiles were observed in E. coli and two in C. diversus. Plasmids responsible for ESBL production could be transferred by conjugation to E. coli K(12) J53-2 from all E. coli isolates and from four of seven K. pneumoniae. No plasmid transfer could be obtained from C. diversus strains. Restriction enzyme digests of plasmids from transconjugants (four transconjugants of K. pneumoniae and five transconjugants of E. coli) showed different patterns. In the surgical intensive care unit where the survey was conducted, the dissemination of ESBLs was due to a mix of strain spread and strain diversity rather than to plasmid dissemination.

Carrier State↗
PubMed2005

Simultaneous enumeration of viable Enterobacteriaceae and Pseudomonas spp. within three hours by multicolor fluorescence in situ hybridization with vital staining.

A new means of rapidly and simultaneously counting viable phylogenetically different bacteria was developed. The cyanine dimer dye, BOBO-3 that selectively stains bacteria with damaged membranes were used to evaluate bacterial viability based on membrane integrity. Viable Enterobacteriaceae and Pseudomonas spp. could be selectively detected within three hours using multicolor fluorescence in situ hybridization (FISH) following BOBO-3 staining (BOBO3-FISH).

Bacteriological Techniques↗
PubMed2006

The role of the Rcs phosphorelay in Enterobacteriaceae.

The Rcs phosphorelay is composed of the sensor kinase, RcsC, the HPt-domain protein RcsD and the response regulator, RcsB. In this review we discuss the role of the Rcs phosphorelay in the Enterobacteriaceae, highlighting the observation that the Rcs phosphorelay appears to play a key role in the temporal regulation of biofilm formation and pathogenicity.

Bacterial Adhesion↗
PubMed2006

The beta-lactamase threat in Enterobacteriaceae, Pseudomonas and Acinetobacter.

Over the past 60 years, the use of successive generations of beta-lactam antibiotics has selected successive generations of beta-lactamase enzymes, each more potent than the last. Currently, rising problems include CTX-M extended-spectrum beta-lactamases (ESBLs), plasmid-mediated AmpC beta-lactamases and KPC carbapenemases in Enterobacteriaceae, while OXA- and metallo- carbapenemases are of growing importance in Acinetobacter spp. and (less so) in other non-fermenters. Escherichia coli isolates with CTX-M ESBLs are spreading multiresistance in the community and in hospitals, while carbapenemase-producing Acinetobacter spp., mostly from intensive care, are among the most multiresistant nosocomial bacteria known and are often susceptible only to polymyxins and, potentially, tigecycline. This review discusses the epidemiology and microbiology of these resistance problems, along with possible solutions.

Acinetobacter↗
PubMed1975

The role of vaginal colonization with enterobacteriaceae in recurrent urinary infections.

Quantitative cultures of the vaginal introitus for Enterobacteriaceae, S. faecalis and P. aeruginosa were compared in 20 premenopausal normal women (200 cultures) to 198 consecutive cultures from 9 premenopausal women in between episodes of bacteriuria. Introital colonization in patients susceptible to urinary infections was significantly higher for E. coli (p equals 0.001), S. faecalis (p equals 0.001) and for the presence of any gram-negative pathogens (p equals less than 0.001). In addition, introital colonization with these bacteria occurred in larger numbers and persisted through consecutive cultures for longer periods in women with recurrent infections.

Enterobacteriaceae↗