GC content of DNA of Campylobacter pylori and other species belonging or related to the genus Campylobacter

DNA of type strain Campylobacter pylori NCTC 11637 and 32 other strains of C. pylori recovered from gastric biopsy specimens was examined by thermal denaturation for its guanine-plus-cytosine (GC) content. The GC content of strain NCTC 11637 was 35.6 mol % (standard deviation (SD) 0.3), and the GC content of the 32 other C. pylori strains ranged from 34.1 to 37.5 mol % (average value 35.2, SD 1.0). A total of 14 type strains of other Campylobacter and Wolinella species were included in this study and the results obtained were compared with those cited in the literature.

Evaluation of autoscan-4 for identification of members of the family Enterobacteriaceae

A study was performed to compare the Autoscan-4 (MicroScan, Inc., Mahwah, N.J.) with conventional biochemical methods for identifying clinical isolates of the family Enterobacteriaceae. The Autoscan-4 yielded correct identification of 95.4% of the isolates at the species level and 98.4% at the genus level. Only one misidentification was observed. The identification of both common and less-common isolates of Enterobacteriaceae makes this system highly efficient.

Susceptibilities to antibiotics and antiseptics of new species of the family Enterobacteriaceae

One hundred and sixty-nine strains of new species of the family Enterobacteriaceae, isolated mainly from the environment, were tested to determine their susceptibilities to 13 antibiotics and 4 antiseptics or disinfectants. All the species were susceptible to aminoglycosides, doxycycline, and trimethoprim but were resistant to chloramphenicol. Susceptibility to beta-lactams varied more among the strains. However, all the strains were cefotaxime susceptible, apart from some Buttiauxella agrestis strains for which MICs were greater than 256 micrograms/ml. The antiseptic MBCs were similar to those published elsewhere for species of the Enterobacteriaceae of clinical origin. No resistance to chlorhexidine was observed. On the other hand, the environmental strains presented a greater resistance to active chlorine than did the reference strains.

Immunological relationship among glyceraldehyde-3-phosphate dehydrogenases in the genera Enterobacter and Escherichia

The comparative immunological study of glyceraldehyde-3-phosphate dehydrogenase (G-3-PDH) among Enterobacteriaceae carried out with an anti-Enterobacter cloacae G-3-PDH serum pointed out the large heterogeneity of the genera Enterobacter and Escherichia. The use of two-dimensional maps integrating our new data and previously acquired quantitative data confirmed these results.

A rapid chemical procedure for isolation and purification of chromosomal DNA from gram-negative bacilli

A rapid and simple method for preparing chromosomal DNA from gram-negative bacilli is presented. It is based on the alkaline (NaOH 0.03 M) lysis of cell walls. The resulting emulsion is purified by proteinase K (0.625 mg/g of wet wt), SDS, and the deproteinizing agent (chloroform isoamyl alcohol). The purity, molecular nature, and yield of DNA obtained by the present method are compared with those of DNA extracted by Marmur's procedure and a Marmur's modified procedure. We have developed and standardized this original method to isolate double-stranded DNA, free of proteins and RNA contamination and with a significantly higher yield of DNA than the two other methods. This procedure is particularly useful for strains with low growth and can be applied in every field concerned with DNA analysis.

[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.

Antigenic specificity of Escherichia coli alkaline phosphatase studied with monoclonal antibodies: immunological characterization of E. coli and Shigella strains

Monoclonal antibodies (MoAb) to the alkaline phosphatase of Escherichia coli were produced from spleen cells of BALB/c mice primed with purified alkaline phosphatase of E. coli and SP2O/Ag-14 myeloma cells. Five stable clones were established. They all produced antibodies which reacted by enzyme-linked immunosorbent assay (ELISA) with alkaline phosphatase of all E. coli (25 strains) independently of their origin (drinking water, saline water, surface water, faecal or clinical origin), and with that of four Shigella species (7 strains) tested. Four of these MoAb gave a positive reaction with 52% (MoAb 4G10), 73% (MoAb 4F8, MoAb 4G6) and 89% (MoAb 3C8) of 14 other bacterial species (30 strains) studied, while one (MoAb 2E5) did not react with alkaline phosphatase of these unrelated bacterial strains and thus appeared specific for E. coli and Shigella species. This MoAb was still detectable in ascitic fluids at 1/500,000 in ELISA, and detected all E. coli strains in an indirect immunofluorescence assay at 1/100. It could therefore be used as a reagent for routine detection of E. coli in drinking water, foods or clinical specimens.

Nosocomial infection and colonization by Klebsiella trevisanii

During an 18-month period we identified two cases of septicemia and 24 examples of colonization of humans by Klebsiella trevisanii. Organisms were identified using the API 20EC and API 147 assimilation galleries. Of 147 clinical isolates initially identified as K. oxytoca, 18% were found to be K. trevisanii. Tracheal aspirate was the most common source of the organism. An extensive environmental sampling survey in the rooms of 12 colonized patients revealed a possible reservoir of the organism only once (a face cloth).

Separation of Escherichia adecarboxylata from the "Erwinia herbicola-Enterobacter agglomerans" complex and from the other Enterobacteriaceae by nucleic acid and protein electrophoretic techniques

The species Escherichia adecarboxylata was examined for DNA relatedness to the "Erwinia herbicola-Enterobacter agglomerans" complex and to other members of the family Enterobacteriaceae. DNA-DNA hybridizations (nitrocellulose filter method) showed that strains received as E. adecarboxylata were highly related to each other (73-100% homology). Three strains of E. agglomerans and one strain of E. herbicola showed, respectively, 77, 96, 97 and 92% relatedness with the labelled DNA of E. adecarboxylata. Two groups (E2 and E3) of "atypical coliforms" previously described by Gavini et al. (1983) showed high reassociation values (76-79% and 80-89%, respectively) with E. adecarboxylata. Most of these strains produced similar or nearly identical protein electrophoregrams. All these strains were therefore classified in E. adecarboxylata. This taxon yielded hybridization values lower than 53% with the previously described phenetic or genetic groups belonging to or related to the "herbicola-agglomerans" complex and values lower than 64% with 56 other species of the Enterobacteriaceae. It was concluded that E. adecarboxylata is a species different from E. agglomerans and the other species of the family Enterobacteriaceae. A new definition of the species E. adecarboxylata is presented.

[Immunological study of glyceraldehyde-3-phosphate dehydrogenase in Enterobacteriaceae; taxonomic value]

The antigenic structure of glyceraldehyde-3-phosphate dehydrogenase of the most representative Enterobacteriaceae species were compared with an antiserum to Escherichia coli glyceraldehyde-3-phosphate dehydrogenase. The results of the immunodiffusion experiments were confirmed and specified by micro-complement fixation studies. They demonstrated a total immunological identity between the E. coli enzyme and the enzymes of Alcalescens-dispar and the Shigella species, a marked relatedness of the Salmonella species enzyme and a more or less significant relation of the enzymes of the other Enterobacteriaceae species. Moreover, the micro-complement fixation had the same sensitivity and a better selectivity than the DNA/DNA hybridizations. The results show that, like DNA polymerase, this enzyme has evolved more slowly than the other enzymes studied at this time.

[Study of the species "Enterobacter gergoviae" by DNA/DNA hybridization (author's transl)]

A DNA/DNA hybridization study was carried out with 13 strains of Enterobacter gergoviae and 123 strains of Enterobacteriaceae, Mostly Enterobacter and Klebsiella species. E. gergoviae strains were very highly related (relative binding ratios: 88-96%) to the type strain CIP 76-01, as previously reported by Brenner and co-workers. No close genomic relationship was found with other species of Enterobacter and Klebsiella (mean relative binding ratio: 39%) and other Enterobacteriaceae.

[On the coliform organisms and their count in water supply analysis (author's transl)]

Many psychrotrophic coliform organisms are isolated from samples of water supply. They are coming from water or soil and not from animal faeces. It is therefore necessary to identify coliform organisms to interpret accurately the results of potability analysis.

[Taxonomic study of enterobacteria belonging or related to Escherichia coli species]

Phenetic (numerical analysis) and genetic (DNA-DNA hybridization) studies were carried out on strains belonging or related to the species Escherichia coli. They have shown the diversity of its phenotypes, by the presence of plasmidic characters (citrate+, urease+, H2S+, tetrathionate reductase+, raffinose+, and saccharose+). New strains related phenetically to E. coli are also individualized. They showed less than 30% DNA relatedness with E. coli. A new definition of E. coli is presented.

Etude taxonomique d'entérobactéries appartenant ou apparentées à l'espèce Escherichia coli

Phenetic (numerical analysis) and genetic (DNA–DNA hybridization) studies were carried out on strains belonging or related to the species Escherichia coli. They have shown the diversity of its phenotypes, by the presence of plasmidic characters (citrate+, urease+, H2S+, tetrathionate reductase+, raffinose+, and saccharose+). New strains related phenetically to E. coli are also individualized. They showed less than 30% DNA relatedness with E. coli. A new definition of E. coli is presented.

Evaluation of Micro-ID, for identification of Enterobacteriaceae

Micro-ID system is a new identification kit for Enterobacteriaceae which provides the identification at the species level 4 hours after primary isolation. When compared with conventional biochemical tube media, micro-ID gave a 94% agreement. Comparison of Micro-ID with Api 20 E showed a 90% agreement. A comparison of all 3 systems showed that for 90% of the time, the isolates were named the same by the all systems.