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Biomedical subjects

S L On

Publications and source records attributed to S L On.

52 records · Page 3Linked to original sources
PubMed1994

Helicobacter pullorum sp. nov.-genotype and phenotype of a new species isolated from poultry and from human patients with gastroenteritis.

Campylobacter-like organisms were isolated from the liver, duodenum and caecum of broiler and layer chickens, and from humans with gastroenteritis. They formed a unique DNA homology group and a polyphasic taxonomic analysis was made of 16 strains. Analysis of the nucleotide sequence of the 16S rRNA gene from seven of the strains identified them as belonging to a single species, within the genus Helicobacter. This conclusion was supported by the studies of relative DNA homology and of total protein electrophoretic patterns. The new species could be biochemically differentiated from other helicobacters and its ultrastructure in the electron microscope was typical of the genus except that the flagellum was not sheathed. We propose the name Helicobacter pullorum sp. nov. for this group. Like H. fennelliae or H. cinaedi it represents another non-gastric urease-negative Helicobacter species colonizing the lower bowel. Its isolation from the livers of chickens with vibrionic hepatitis is significant. We describe a species-specific PCR assay for H. pullorum sp. nov. which will facilitate its identification and further studies of its epidemiology.

Animals↗
PubMed1994

Investigation of an outbreak of Clostridium difficile infection in a general hospital by numerical analysis of protein patterns by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

One hundred forty-five cultures of Clostridium difficile, including strains from an apparent nosocomial outbreak of infection, were characterized by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell proteins. Each protein pattern was characterized by the presence of one to three dense bands which were highly reproducible. The first 100 strains (in chronological order) were used as the basis for a numerical analysis which divided the strains into 17 phenons (EP types 1 to 17). The protein patterns of the remaining 45 strains were identified to type by comparing their individual patterns against a data base made up of the protein patterns of the first 100 strains. EP type 1 was the most common, with 70 of 139 (50%) patient isolates having this pattern type, and it accounted for 26 of 35 strains (74%) from patients in a medical teaching ward from which the outbreak was believed to have originated. This type was also found as a high proportion of isolations in a number of other medical and oncology wards, but the majority of these isolates occurred subsequent to the isolations on the initial outbreak ward. This technique can therefore provide a method for tracing the possible spread of epidemic strains in hospitals and other institutions and may contribute to a better understanding of the epidemiology of C. difficile.

Adolescent↗
PubMed1994

Evaluation of Biolog system for identification of some gram-negative bacteria of clinical importance.

The Biolog system (Biolog, Inc., Hayward, Calif.) was evaluated for the identification of 55 gram-negative taxa (789 strains) likely to be encountered commonly in clinical laboratories. The Biolog system performed best with oxidase-positive fermenters and biochemically active nonfermenters and had the most problems with unreactive nonfermenters. It gave significantly better results when the MicroPlates were read manually rather than when they were read by the automated reader. Plates read manually gave the following performances: oxidase-positive fermenters, five taxa, 64 strains, 92% correct, 3% not identified, and 5% incorrect; biochemically active nonfermenters, eight taxa, 122 strains, 88% correct, 6% not identified, and 6% incorrect; members of the family Enterobacteriaceae, 35 taxa, 511 strains, 77% correct, 8% not identified, and 15% incorrect; unreactive nonfermenters, seven taxa, 92 strains, 38% correct, 24% not identified, and 38% incorrect. We found the system easy to use, but while for 39 of 55 of the taxa an identification rate of > 70% was achieved, problems were encountered, particularly with identification of capsulated strains of some Enterobacter and Klebsiella taxa, as well as the least biochemically active Moraxella and Neisseria strains.

Bacterial Proteins↗
PubMed1994

Confirmation of human Campylobacter concisus isolates misidentified as Campylobacter mucosalis and suggestions for improved differentiation between the two species.

A strain from human diarrhea originally identified as Campylobacter mucosalis (NCTC 12408) was examined by using 64 phenotypic characters. The similarity of this strain to 297 isolates of Campylobacter, Helicobacter, Arcobacter, and related taxa was then determined with a computer-supported data analysis program, MVSP. NCTC 12408 showed closest similarity to 20 type, reference, and field isolates of Campylobacter concisus. These strains were clearly separated from those of C. mucosalis in the numerical analysis of phenotypic tests; a table was constructed from the data used to aid in differentiating these two species in the clinical laboratory. The identity of NCTC 12408 was confirmed as C. concisus by visual comparison of its sodium dodecyl sulfate-polyacrylamide gel whole-cell protein electrophoregram with those of type strains of C. concisus and C. mucosalis. These data suggest that genuine human infection with C. mucosalis has not yet been reported.

Campylobacter↗
PubMed1993

Neisseria weaveri sp. nov. (formerly CDC group M-5), from dog bite wounds of humans.

The taxonomic relationships of strains belonging to Centers for Disease Control group M-5 were examined. Previous studies of rRNA cistron similarities placed this organism on the Neisseriaceae rRNA branch of rRNA superfamily III; the closest neighbors included the genus Neisseria and groups EF-4a and EF-4b. The group M-5 strains were characterized by a range of phenotypic tests, and their G + C contents and DNA-DNA relatedness levels were determined. In addition, a numerical taxonomic analysis of the whole-cell protein patterns (obtained by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) of group M-5 and related taxa was performed. The strains studied included 45 group M-5 strains, the type strains of six Neisseria species or subspecies, three group EF-4a reference strains, and three group EF-4b reference strains plus the type strain of the phenotypically similar organism Oligella urethralis. Our results showed that the group M-5 strains were members of a homogeneous taxon distinct from phylogenetically closely related taxa. The genomic divergence as revealed by levels of rRNA cistron similarity and phenotypic characteristics indicate that group M-5 can be considered a new species of the genus Neisseria. We therefore propose the new species Neisseria weaveri, with NCTC 12742 (= CCUG 4007 = ISL775/91 = LMG 5135) as the type strain. N. weaveri strains are strictly aerobic, gram-negative, nonmotile, rod-shaped organisms which are catalase and oxidase positive, nonsaccharolytic, and able to grow on MacConkey agar and do not reduce nitrate but generally reduce nitrite.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Helicobacter canis sp. nov., a new species from dogs: an integrated study of phenotype and genotype.

A group of Campylobacter-like organisms (CLOs) were isolated from the faeces of diarrhoeic or healthy dogs, constituting 4% of all CLOs from this source. Since they formed a unique DNA homology group within the genus Helicobacter, and exhibited distinctive phenotypic properties, they were collectively termed the HC group. A polyphasic taxonomic analysis was made of this group. The phenotype of four dog isolates and a single human isolate was unique and could be distinguished bacteriologically from other helicobacters. Electron microscopic ultrastructure revealed defining characteristics of Helicobacter. The 16S rRNA gene of the nominated type strain NCTC 12739T was sequenced, and its analysis delineated the group as a new species of Helicobacter. This conclusion was supported by relative DNA homology and whole-cell protein electrophoretic patterns. We therefore propose the name Helicobacter canis sp. nov. for this group. The species most closely related to H. canis sp. nov. were H. cinaedi, 'Flexispira rappini' and H. fennelliae. A species-specific recombinant DNA probe was cloned from NCTC 12739T for use in routine laboratory identification and epidemiological studies. The faecal source, bile tolerance and lack of urease activity of H. canis sp. nov. suggest that this new Helicobacter species colonizes the lower bowel rather than the stomach.

Animals↗
PubMed1992

Isolation of Campylobacter sputorum biovar sputorum from an axillary abscess.

Campylobacter sputorum biovar sputorum is a rarely isolated organism, particularly from human clinical specimens. Its pathogenic potential is unknown. We present here what we believe to be the first report of this organism being isolated from a clinically significant source, an axillary abscess. To our knowledge, this organism has not been reported previously as one of clinical relevance in the U.K.

Abscess↗
PubMed1992

Campylobacter helveticus sp. nov., a new thermophilic species from domestic animals: characterization, and cloning of a species-specific DNA probe.

An atypical group of thermophilic catalase-negative Campylobacter strains, the 'CH' (Swiss) group, can be recovered from faeces of domestic cats and dogs after selection by filtration, or with the antibiotic cefoperazone. This group of strains shows no relative DNA homology with any species in rRNA superfamily VI (Vandamme et al., 1991, International Journal of Systematic Bacteriology 41, 88-103) except with four thermophilic Campylobacter species, notably C. upsaliensis. The group is homogeneous and possesses a DNA base composition, cellular morphology at the electron microscope level and phenotypic properties characteristic of Campylobacter. Nonetheless it is distinct from known species of Campylobacter in terms of conventional bacteriological tests, total cellular protein profile, rRNA gene profile, and genomic DNA homology. On the basis of an integrated study of phenotype and genotype, we conclude that these bacteria constitute a previously undescribed species for which we propose the name Campylobacter helveticus sp. nov. A species-specific recombinant DNA probe was cloned from the designated type strain (NCTC 12470) for use in identification and further analysis of the epidemiology, pathogenicity and transmission of C. helveticus.

Animals↗
PubMed1992

Assessment of enzyme detection tests useful in identification of campylobacteria.

Twenty-one type or other reference strains, each representing a different Campylobacter, Helicobacter, or Arcobacter taxon, and a reference strain of Staphylococcus aureus were used to assess the reproducibility of nine enzyme detection tests used in the identification of campylobacters. For five of the tests (alkaline phosphatase, DNase, and H2S production, indoxyl acetate hydrolysis, and nitrate reduction), more than one procedure was employed to determine the most suitable method. Alkaline phosphatase test results were better defined and more reproducible if read after 1 h of incubation. Detection of DNase was fully reproducible with each method (except with Helicobacter pylori), but reactions were generally weaker than those of other DNase-producing organisms. Both procedures for determining H2S production were irreproducible for the same strains. The reproducibility of indoxyl acetate hydrolysis was improved by using disks impregnated with 25 microliters of substrate. Reduction of nitrate was best determined by Cook's plate method. Results for the other tests examined (catalase, oxidase, and urease production and hippurate hydrolysis) were both pertinent and fully reproducible for all strains.

Alkaline Phosphatase↗
PubMed1991

Effect of inoculum size on the phenotypic characterization of Campylobacter species.

The type strains of six Campylobacter species or subspecies were examined in eight tests used for the identification of such organisms. False-positive results were obtained in certain tests (growth on 1% bile, brilliant green, selenite, trimethylamine-N-oxide, 2,3,5-triphenyl tetrazolium chloride, and minimal media) when an inoculum yielding 10(7) to 10(8) CFU/ml was used. Each tolerance test was examined with blood, nutrient, and brucella agars as basal media. The type of basal medium used could also affect the test outcome. With the inoculum standardized to a density yielding approximately 10(6) CFU/ml, reproducible and pertinent results were obtained, provided an appropriate basal medium was used. However, 95% confidence limits for viable counts done on these basal media indicated that blood agar may yield more consistent results than the other agars examined.

Agar↗
PubMed1991

Reproducibility of tolerance tests that are useful in the identification of campylobacteria.

Twenty type or other reference strains, each representing a different Campylobacter, Helicobacter, or Arcobacter taxon, were used to assess the reproducibility of 25 phenotypic tests that are used in the identification of such organisms. Twenty-two of the tests depended on growth inhibition, and each of these tolerance tests was performed by using three different basal media. Although the overall reproducibility of the tests with each basal medium exceeded 89%, the proportion of strains that were able to grow in a reproducible manner on the basal media varied from 100% for blood agar and 50% for nutrient agar to 5% for brucella agar. In general, test reproducibility was highest with the basal medium that supported the most luxuriant growth. For the majority of tests, the basal medium which gave the optimum reproducibility could be determined.

Animals↗
PubMed1989

Strain variation in Campylobacter pylori detected by numerical analysis of one-dimensional electrophoretic protein patterns.

A total of 21 clinical isolates of Campylobacter pylori from Peru and the United Kingdom and two reference strains (from Australia), including the type strain (NCTC 11637T), were characterized by high resolution one-dimensional SDS-polyacrylamide gel electrophoresis of cellular proteins. The protein patterns contained more than 40 discrete bands and the approximate molecular weights of the major bands were 22, 27, 46, 57, 60, 65 and 93 kD. The total patterns were used as the basis of numerical analysis. Most strains were clustered in four phenons at 91% similarity with the exception of six ungrouped strains. Overall similarity was high with all strains linked in the phenogram at greater than or equal to 81%. Variation among strains was attributable principally to qualitative and quantitative band differences in the 47 to 56 kD (hypervariable) region of the C. pylori protein profile. From the analysis, ten different electropherotypes (EP-types) were identified. We demonstrated that differences were detectable among isolates from widely separated geographical locations as well as from the same location, although multiple isolates from two Peruvian patients had the same electropherotype. Our results indicate that determination of protein profiles provides the basis of a reproducible method for characterization of C. pylori isolates.

Bacterial Proteins↗
PubMed1989

The effect of cooling rate, freeze-drying suspending fluid and culture age on the preservation of Campylobacter pylori.

The effects of freezing rate, suspending fluid and age of culture on the ability of four strains of Campylobacter pylori to survive and recover from freeze-drying were examined. Freeze-drying by standard procedures generally resulted in an overall loss in viability of between 3 and 7 log units. The exact cause of poor recovery by C. pylori was not established but strain differences were detected, with NCTC 11637 (type strain) surviving better than NCTC 11638 and NCTC 11639. Recovery of the poorest growing strain (NE 26695) was notably more erratic. The largest loss in viability occurred at the primary drying stage. Losses resulting from freezing and secondary drying were less marked and the rate of freezing had only a marginal effect on recovery. Nineteen different freeze-drying suspending fluids were investigated. Overall the best recovery results were obtained with 5% inositol-broth (or horse serum) plus 25% glucose, at pH 7.0, in which loss of viability was typically about 4 log units. Other factors, such as age of culture and number of viable bacteria in the before-dry suspension, did not have a significant effect on survival. We conclude from these results that C. pylori can survive freeze-drying, albeit in small numbers, but the degree of recovery is apparently largely strain dependent.

Campylobacter↗
PubMed1989

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.

Animals↗
PubMedDate not supplied

A cultured strain of "Helicobacter heilmannii," a human gastric pathogen, identified as H. bizzozeronii: evidence for zoonotic potential of Helicobacter.

We compared the characteristics of a cultured human "Helicobacter heilmannii" isolate with those of other helicobacters found in animals. Phenotypic, protein profile, 16S rDNA sequence, and DNA-DNA hybridization analyses identified the human strain as H. bizzozeronii, a species frequently found in dogs. Thus, H. bizzozeronii may have zoonotic potential.

Animals↗