Aims: To assess the ef®cacy of numerical analysis of PFGE-DNA pro®les for identi®cation and differentiation of Campylobacter fetus subspecies. Methods and Results: 31 Camp. fetus strains were examined by phenotypic, PCR-and PFGE-based methods, and the 16S rDNA sequences of 18 strains compared. Numerical analysis of PFGE-DNA pro®les divided strains into two clusters at the 86% similarity level. One cluster contained 19 strains clearly identi®ed as Camp. fetus subsp. venerealis. The other cluster comprised 12 strains, of which 10 were unambiguously identi®ed as Camp. fetus subsp. fetus. The remaining two strains were identi®ed as Camp. fetus subsp. venerealis by either phenotypic or PCR methods, but not both. At higher similarity levels, clusters containing isolates from each of two countries were identi®ed, suggesting that certain clones predominate in certain geographical regions. Conclusions: Numerical analysis of PFGE-DNA pro®les is an effective method for differentiating Camp. fetus subspecies. Signi®cance and Impact of the Study: Critical comparison of PFGE, PCR, 16S rDNA sequencing and phenotypic methods for differentiation of Camp. fetus subspecies was attained. Novel phenotypic markers for distinguishing subspecies were identi®ed. Evidence for dominant clones of each subspecies in certain countries was provided.

The flagellin subunit of the flagellar filament in Campylobacter jejuni is encoded by two highly homologous tandem genes, flaA and flaB. The flaA gene was sequenced in 18 strains of C. jejuni, including isolates from three outbreak groups. Sequences obtained were compared with flaA sequences available in the GenBank database, and all were analyzed for mosaic gene structure by using recently described statistical tests for detecting gene conversion among aligned sets of sequences. Strong evidence was found supporting recombination between flaA genes of different strains (i.e., intergenomic recombination). Intragenomic recombination between the flaA and flaB genes of C. jejuni TGH9011 was also demonstrated. Both mechanisms of recombination may act as a potential means by which pathogenic strains can generate increased antigenic diversity, so allowing them to escape the immunological responses of the host. Furthermore, demonstration of recombination within and between flagellin loci of natural strains suggests that flagellin gene typing (restriction fragment length polymorphism analysis of PCR-amplified flagellin genes) cannot be considered a stable method for long-term monitoring of pathogenic Campylobacter populations.

A 1-year study was undertaken to determine the prevalence of Arcobacter spp. in raw milk and retail raw meats on sale in Northern Ireland. Retail raw poultry samples (n = 94), pork samples (n = 101), and beef samples (n = 108) were obtained from supermarkets in Northern Ireland, and raw milk samples (n = 101) were kindly provided by the Milk Research Laboratory, Department of Agriculture and Rural Development, Belfast, Northern Ireland. Presumptive arcobacters were identified by previously described genus-specific and species-specific PCR assays. Arcobacter spp. were found to be common contaminants of retail raw meats and raw milk in Northern Ireland. Poultry meat (62%) had the highest prevalence, but frequent isolations were made from pork (35%), beef (34%), and raw milk (46%). Arcobacter butzleri was the predominant species isolated from retail raw meats and was the only species isolated from raw milk samples. Arcobacter cryaerophilus was detected less frequently, and Arcobacter skirrowii was detected only as a cocontaminant. To our knowledge, this is the first report of Arcobacter spp. prevalence in a diverse range of products of animal origin in Northern Ireland.

A polyphasic taxonomic study of 15 bovine and human strains assigned to the catalase-negative, urease-positive campylobacter (CNUPC) group identified these bacteria as a novel, ureolytic biovar of Campylobacter sputorum for which w e propose the name C. sputorum bv. paraureolyticus : suitable reference strains are LMG 11764 (human isolate) and LMG 17590 (= CCUG 37579, bovine isolate). The present study confirmed previous findings showing that the salient biochemical tests used to differentiate C. sputorum bv. sputorum from C. sputorum bv. bubulus are not reproducible; and that the absolute validity of source-specific biovars of the species is questionable. A correlation between the results of numerical analysis of protein profiles and the reaction of strains in certain enzyme tests was, however, noted. Therefore, it is proposed that the infrasubspecific (biovar) divisions of C. sputorum should be revised to include bv. sputorum for catalase-negative strains; bv. fecalis for catalase-positive strains; and bv. paraureolyticus for urease-positive strains. Strains classified previously as bv. bubulus should be reclassified as bv. sputorum. The species description of C. sputorum is revised accordingly.

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Ph y logenet ic relationships of Campylobacter hyointestinalis subspecies were examined by means of 16s rRNA gene sequencing. Sequence similarities among C. hyointestinalis subsp. Iawsonii strains exceeded 99.0 %, but values among C. hyointestinalis subsp. hyointestinalis strains ranged from 964 to 100 %. Sequence similarites between strains representing the two different subspecies ranged from 95.7 to 990%. An intervening sequence was identified in certain of the C. hyointestinalis subsp. lawsonii strains. C. hyointestinalis strains occupied two distinct branches in a phylogenetic analysis of the genus Campylobacter, emphasizing the need for multiple strain analysis when using 165 rRNA gene sequence comparisons for taxonomic investigations.

Aims: To use amplified fragment length polymorphism (AFLP) analysis to evaluate the genetic relatedness among 254 Campylobacter jejuni reference and field strains of diverse origin representing all defined ÔPennerÕ serotypes for this species. Methods and Results: Field strains (n ¼ 207) from human diarrhoea and diverse animal and environmental sources were collected mainly through a National surveillance programme in Denmark and serotyped by use of the established ÔPennerÕ scheme. Genetic relationships among these isolates, and the archetypal serotype reference strains, were assessed by numerical analysis of AFLP profiles derived from genomic DNA. Extensive genetic diversity was seen among the strains examined; however, 43 groups of isolates were identified at the 92% similarity (S-) level. Thirteen groups contained isolates from a single host, possibly representing genotypes of Ôlow riskÕ to human health. The remaining 30 groups contained isolates from humans, chickens and associated food products, cattle, sheep, turkeys, ostriches and/or dogs. Strains assigned to serotypes 2, 6/7, 11 and 12 formed major clusters at the 77AE6% S-level. Most other serotypes did not form homogeneous clusters. Conclusions: High-resolution genotyping applied to strains from a comprehensive range of sources provides evidence for multiple sources of sporadic C. jejuni infection. The results suggest that public health protection measures should be directed at all foods of animal origin. Significance and Impact of the Study: The genetic relatedness among all ÔPennerÕ serotypes of C. jejuni is assessed by AFLP analysis. In addition, further evidence of epidemic and host-specific clones of C. jejuni is provided.

Aims:  To develop a PCR‐denaturing gradient gel electrophoresis (PCR‐DGGE) method for the detection and identification of Campylobacter, Helicobacter and Arcobacter species (Epsilobacteria) in clinical samples and evaluate its efficacy on saliva samples from humans and domestic pets. Methods and Results:  A semi‐nested PCR was developed to allow sensitive detection of all Epsilobacteria, with species separation undertaken by DGGE. A database was constructed in BioNumerics using 145 strains covering 51 Campylobacter, Arcobacter and Helicobacter taxa; Nineteen distinct DGGE profile‐groups were distinguished. This approach detected Epsilobacteria in all saliva samples collected from humans, cats and dogs, and identified Campylobacter concisus and/or Campylobacter gracilis in the human samples. The pet animal samples were taken from individuals with oral/dental diseases; PCR‐DGGE identified up to four different species in each sample. The most common species detected included Wolinella succinogenes, Arcobacter butzleri and two hitherto uncultured campylobacters. The enteropathogen Campylobacter lari was also found. Conclusions:  PCR combined with DGGE is a useful tool for direct detection and preliminary identification of Epsilobacteria in the oral cavity of humans and small animals. Significance and Impact of the Study:  The PCR‐DGGE method should allow determination of the true prevalence and diversity of Epsilobacteria in clinical and other samples. Contact with the oral cavity of domestic pets may represent a route of transmission for epsilobacterial enteric diseases.