DNA base compositions and base sequence relatedness of atypicalCampylobacter jejunistrains from clinical material

DNA-DNA hybridization and analysis of restriction endonuclease and rRNA gene patterns of atypical (catalase-weak/negative) Campylobacter jejuni from paediatric blood and faecal cultures

Sixteen strains of atypical (catalase-weak or negative), hippurate-hydrolysing campylobacters from paediatric blood and faecal cultures were identified by DNA-DNA slot hybridization. All were closely related (greater than or equal to 67%) to Campylobacter jejuni and representative strains had G + C contents of 30 +/- 1 mol%. Numerical analysis of chromosomal DNA HaeIII digest patterns revealed two clusters of strains at the 55%S level corresponding to C. jejuni subsp. jejuni and C. jejuni subsp. doylei; most strains belonged to the latter subspecies. No two strains had identical patterns but within each subspecies two subgroups were identifiable, corresponding to Lior biotypes I and II. Southern blot hybridization analysis with a 16 + 23S rRNA cistron probe from Escherichia coli also showed differences between the various strains, and in a numerical analysis three groupings were formed at 70%S corresponding to C. jejuni subsp. jejuni Lior biotypes I and II, and C. jejuni subsp. doylei. Four of the subspecies doylei strains contained a 3.4-MDa plasmid. These analyses showed that catalase-negative C. jejuni subsp. jejuni were genomically distinguishable from C. jejuni subsp. doylei as were Lior biotypes within subsp. jejuni. Ability to produce catalase is not a feature common to all C. jejuni strains, and our results confirm that some strains of subspecies jejuni may be negative in that character although typical in other respects. DNA pattern heterogeneity was consistent with serological differences between strains.

Identification of EF group 22 campylobacters from gastroenteritis cases as Campylobacter concisus

EF (E. Falsen) group 22, a group of Campylobacter strains sorted out by routine immunotyping among unidentified or misidentified human nonoral clinical specimens, was characterized by numerical analysis of gel electrophoretic protein profiles and immunotyping. The protein electrophoretic and immunotyping analyses, DNA:DNA hybridizations, and the DNA base composition demonstrated unambiguously that all EF group 22 strains belong to Campylobacter concisus. EF group 22 strains have DNA binding values of at least 42% with the type strain of C. concisus, showing a considerable degree of genomic heterogeneity. The isolation from blood, esophagus, stomach, duodenum, and feces of humans in association with different gastrointestinal disorders considerably extends the clinical significance of this species. Our results indicate that sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunotyping are excellent tools for the identification of the fastidious C. concisus strains and relatives.

Electrophoretic protein typing of Campylobacter jejuni subspecies "doylei" (nitrate-negative campylobacter-like organisms) from human faeces and gastric mucosa

Twenty-seven strains comprising 23 clinical isolates of nitrate negative campylobacters (NNC) from Australia, South Africa, the United Kingdom and the Federal Republic of Germany, a representative of the CNW (catalase negative/weak) group and reference strains of three other Campylobacter species, were characterized by one-dimensional SDS-polyacrylamide gel electrophoresis of cellular proteins. The protein patterns were highly reproducible, and were used as the basis for a numerical analysis which showed that the reference strain (NCTC 11951) of Campylobacter jejuni subspecies "doylei", and 20 NNC isolates formed a distinct group at the 74% similarity level. The protein patterns showed unexpectedly low similarity between subspecies "doylei" and the type strain of Campylobacter jejuni and revealed that some NNC strains were quite distinct from subspecies "doylei". Four electrophoretic (EP) types (I-IV) were identified from phenons formed at the 81% similarity level. Three of these (I, III, IV) corresponded to geographical location of strain isolation but the type II strains were from diverse locations. The correlation observed between EP-type, catalase production and sensitivity to 2, 3, 5, triphenyltetrazolium chloride indicated these latter two tests might be useful for biotyping within the subspecies.