Stephen L.W. On

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.

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.

A Sustained Outbreak of Clostridium difficile in a General Hospital: Persistence of a Toxigenic Clone in Four Units

OBJECTIVEnTo evaluate the endemicity and epidemiology of toxigenic Clostridium difficile in a sustained outbreak of antibiotic-associated diarrhea.nnnSETTINGnUniversity-affiliated, 465-bed tertiary care teaching hospital with adjacent cancer clinic in Hamilton, Ontario.nnnDESIGNnFrom August 8, 1991, through August 31, 1993, a total of 187 cases were investigated for epidemiologic analysis of toxigenic C difficile from stool cultures, to identify the endemic clone(s). To assess the nature of contamination, cultures of inanimate surfaces in the patient environment from the four most affected units (medical teaching, nonteaching medical, hematologic oncology, and the intensive care unit) were processed for C difficile. The 229 clinical strains and 24 environmental strains isolated were typed by numerical analysis of SDS-PAGE protein patterns.nnnRESULTSnA majority (81%) of cases in the epidemiologic analysis were associated with a toxigenic electrophoretic (EP) type 1 C difficile that was identical to the strain first isolated from an index case that occurred 18 months before the start of this study. Culture and typing of the C difficile strains from the inanimate surfaces in the four most affected units showed that the patient environment was contaminated with the toxigenic EP type 1 organism. Six other strains that occurred infrequently among cases also were found in the environment.nnnCONCLUSIONSnA single predominant toxigenic clone has been implicated in a sustained outbreak of antibiotic-associated diarrhea that affected elderly patients. The endemic clone transmitted for the 25-month study period was linked to an index case shedding a toxigenic EP type 1 strain that occurred 21 months prior to the initial outbreak on the medical teaching unit. The patient environment in the affected units was found to be contaminated with the same clone, possibly due to shedding of organisms by fecally incontinent symptomatic patients. The extrinsic factors contributing to the endemic transmission of this one clone still are not well understood.

Classification and Identification of Campylobacters, Helicobacters and Allied Taxa by Numerical Analysis of Phenotypic Characters

Summary The value of numerical analysis of phenotypic characters for the classification and identification of campylobacteria was investigated. Sixty-seven phenotypic characters were determined for 347 strains representing forty-three species, subspecies, biovars or unnamed groups assigned or affiliated to the genera Crmpylobacter, Arcobacter, Helicobacter , and Anaerobiospirillum . The data were subjected to numerical analysis using a computer program, MVSP. The results indicated that, (i) there was considerable agreement between the groupings obtained and previously determined genomic relationships, (ii) most strains could be identified accurately to the specific or subspecific level, and (iii) two novel groups could be delineated. Although highly atypical strains proved difficult to classify, the method has considerable potential for accurately differentiating members of this taxonomically complex and economically important group of bacteria.

Differentiation of Helicobacter Species by Numerical Analysis of their One-Dimensional Electrophoretic Protein Patterns

Summary The suitability of sodium dodecyl sulfate-polyacrylamide gel electrophoretic protein profiles coupled to a computer-assisted numerical analysis for the differentiation of helicobacters was evaluated. Fifty-three strains representing most of the known and available species of Helicobacter and reference strains of allied taxa were included. The results indicate, (i) that the majority of the species examined by this technique could be clearly differentiated, including H. cinaedi and H. fennelliae , which can be difficult to separate by conventional bacteriological methods; two species, H. acinonyx and H. pylori constitute a single phenon at the 69% similarity level and cannot be distinguished at this level, (ii) that gastric helicobacters were more closely clustered to each other than they were to those of enteric origin, (iii) that within several species, different electrophoretic types could be distinguished and that, in the case of the H. pylori/H. acinonyx complex, there appeared to be clustering based on the host source of the strains. Two minor groups (one of human and one of canine origin) were identified and these may merit further phylogenetic analysis.

Classification and Identification of Campylobacter sputorum using Numerical Analyses of Phenotypic Tests and of One-dimensional Electrophoretic Protein Profiles

Summary The application of numerical analyses of phenotypic tests and sodium-dodecyl sulphate polyacrylamide gel electrophoretic protein profiles in the classification and identification of Campylobacter sputorum was examined. Thirty-eight strains received, or isolated as, representatives of each of the defined biovars of Campylobacter sputorum (i.e. bubulus, fecalis, and sputorum), along with seventeen type or reference strains of other Campylobacter, Arcobacter , and Helicobacter species, were studied. The results from both analyses indicated, (i) that thirty-two strains formed a distinct cluster which included the type strain of C. sputorum , confirming their identity as members of this species, (ii) that catalase-positive strains of C. sputorum are associated with faeces, (iii) that the normal subdivision of catalase-negative C. sputorum strains into two source-specific biovars is invalid. Thus, catalase-positive strains of C. sputorum should remain as biovar fecalis and catalase-negative strains (i.e. biovars sputorum and bubulus) should be unified as a single biovar sputorum and the biovar bubulus discarded. Five oral isolates initially believed to be C. sputorum biovar sputorum were identified as potentially novel campylobacters. Numerical analysis of both types of data used were shown to be effective methods of classifying and identifying campylobacters and allied taxa.

Identification and intra-specific heterogeneity of Campylobacter hyointestinalis based on numerical analysis of electrophoretic protein profiles

Summary Sixty-six strains received as Campylobacter hyointestinalis , along with twelve type or reference strains of other Campylobacter species, were characterized using high-resolution one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. The resulting protein patterns were analyzed numerically, by computer, and revealed that when only background patterns were analyzed, 57 of the 66 strains formed a single cluster which included the type strain of C. hyointestinalis , thus confirming their identity. This cluster could be divided into two sub-clusters (a and b) which could also be differentiated phenotypically. When the full patterns were analyzed, 17 electrophoretypes were recognized among the 57 C. hyointestinalis strains. Evidence for the co-existence of strains of different protein types in the digestive tract of a single animal is presented.