Diseases due to Campylobacter, Helicobacter and related bacteria

Serotype and genotype diversity and hatchery transmission of Campylobacter jejuni in commercial poultry flocks

We investigated the genotype and serotype diversity of Campylobacter coli and C. jejuni in two parent flocks of adult hens and their offspring over two rotations in order to evaluate the role of hatchery mediated transmission and/or vertical transmission of campylobacters in broiler flocks. In total, 314 C. jejuni and 32 C. coli isolates from parent and broiler flocks and from the surroundings of broiler houses were typed by flagellin gene PCR/RFLP (fla-typing), and selected isolates were also typed by serotyping and macrorestriction profiling using PFGE (MRP/PFGE). The combined typing results showed that the broiler flocks could be colonised by 1-3 different Campylobacter clones and parent flocks could be colonised by 2-6 different clones. C. coli was isolated from up to 36% of birds in one parent flock, whereas only C. jejuni was isolated from broiler flocks. C. jejuni clones from different flocks were clearly discriminated by fla-typing as well as by MRP/PFGE, except for a few cases where individual isolates belonging to two different clones were found to have altered fla-types. Similarly, one C. coli clone showed pronounced fla-type variation. The present results lead to the conclusion that vertical transmission or horizontal transmission via the hatchery are not significant transmission routes of C. jejuni to broiler chickens under Danish conditions. In the cases where more than one Campylobacter clone simultaneously colonised flocks, we found that the different clones coexisted in flocks rather than excluding each other.

Comparison of genotypes and serotypes of Campylobacter jejuni isolated from Danish wild mammals and birds and from broiler flocks and humans

The incidence of human infection with Campylobacter jejuni is increasing in most developed countries and the reason for this is largely unknown. Although poultry meat is considered to be a major source, it is evident that other reservoirs exist, possibly common to humans and poultry. Environmental sources are believed to be important reservoirs of Campylobacter infection in broiler chicken flocks. We investigated the potential importance of wildlife as a source of infection in commercial poultry flocks and in humans by comparing the serotype distributions, fla types, and macrorestriction profiles (MRPs) of C. jejuni isolates from different sources. The serotype distribution in wildlife was significantly different from the known distributions in broilers and humans. Considerable sero- and genotype diversity was found within the wildlife collection, although two major groups of isolates within serotype O:12 and the O:4 complex were found. Common clonal lines among wildlife, chicken, and/or human isolates were identified within serotype O:2 and the O:4 complex. However, MRPs of O:12 and O:38 strains isolated from wildlife and other sources indicated that some clonal lines propagated in a wide selection of animal species but were not detected in humans or broilers in this study. The applied typing methods successfully identified different clonal groups within a strain collection showing large genomic diversity. However, the relatively low number of wildlife strains with an inferred clonal relationship to human and chicken strains suggests that the importance of wildlife as a reservoir of infection is limited.

Genomic relatedness within five common Finnish Campylobacter jejuni pulsed-field gel electrophoresis genotypes studied by amplified fragment length polymorphism analysis, ribotyping, and serotyping

Thirty-five Finnish Campylobacter jejuni strains with five SmaI/SacII pulsed-field gel electrophoresis (PFGE) genotypes selected among human and chicken isolates from 1997 and 1998 were used for comparison of their PFGE patterns, amplified fragment length polymorphism (AFLP) patterns, HaeIII ribotypes, and heat-stable (HS) serotypes. The discriminatory power of PFGE, AFLP, and ribotyping with HaeIII were shown to be at the same level for this selected set of strains, and these methods assigned the strains into the same groups. The PFGE and AFLP patterns within a genotype were highly similar, indicating genetic relatedness. The same HS serotypes were distributed among different genotypes, and different serotypes were identified within one genotype. HS serotype 12 was only associated with the combined genotype G1 (PFGE-AFLP-ribotype). These studies using polyphasic genotyping methods suggested that common Finnish C. jejuni genotypes form genetic lineages which colonize both humans and chickens.

The isolation and characterization of Campylobacter jejuni subsp. jejuni from domestic geese (Anser anser)

AIMS

The objectives of this study were to determine the presence of thermophilic Campylobacter spp. in free range domestic geese, and to characterize isolated strains using phenotyping criteria and SDS-PAGE of whole-cell proteins.

METHODS AND RESULTS

Forty cloacal swabs from two different flocks of domestic geese were examined. All Camp. jejuni strains isolated from geese were biotyped using the Lior biotyping scheme. Twelve Camp. jejuni isolates were also tested for their susceptibility to 17 different antibacterial agents by a disc diffusion

METHOD

Fourteen of the isolates were also subjected to SDS-PAGE. All of the geese examined were found to harbour Camp. jejuni. Six geese carried more than one species of Campylobacter. All strains examined were susceptible to various antibiotics but resistant to penicillin G and cephalothin. Eleven strains (92%) were resistant to sodium cefuroxime, and eight (67%) were resistant to cloxacillin, ampicillin and colistin sulphate. Three strains (25%) were resistant to tetracycline, and one strain was resistant to sulfamethoxazole/trimethoprim and kanamycin. Nine strains were subtyped as Camp. jejuni subsp. jejuni biotype II and the remaining ones as biotype I. There were 96% and 100% similarities between all the strains examined by SDS-PAGE.

CONCLUSION

This study showed that Camp. jejuni were common in the intestinal tract of domestic geese.

SIGNIFICANCE AND IMPACT OF THE STUDY

Geese should be considered as potential reservoirs for human and animal campylobacteriosis. The antibiotic resistance data from this study also showed that fluoroquinolone resistance, which appears to be a problem in poultry isolates in some countries, is not yet a problem in these geese.

Evaluation of numerical analysis of PFGE-DNA profiles for differentiating Campylobacter fetus subspecies by comparison with phenotypic, PCR and 16S rDNA sequencing methods

AIMS

To assess the efficacy of numerical analysis of PFGE-DNA profiles for identification 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 profiles divided strains into two clusters at the 86% similarity level. One cluster contained 19 strains clearly identified as Camp. fetus subsp. venerealis. The other cluster comprised 12 strains, of which 10 were unambiguously identified as Camp. fetus subsp. fetus. The remaining two strains were identified 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 identified, suggesting that certain clones predominate in certain geographical regions.

CONCLUSION

Numerical analysis of PFGE-DNA profiles is an effective method for differentiating Camp. fetus subspecies.

SIGNIFICANCE 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 identified. Evidence for dominant clones of each subspecies in certain countries was provided.

Chemical structure of the core oligosaccharide of aerotolerant Campylobacter jejuni O:2 lipopolysaccharide

The structure of the core oligosaccharide of aerotolerant Campylobacter jejuni 0:2 lipopolysaccharide was determined and found to contain 3-deoxy-D-manno-octulosonic acid (Kdo), L-glycero-D-manno-heptose (LD-Hep), D-galactose, D-glucose, and phosphorylethanolamine (PEtn). Based on 1H, 13C and 31P NMR spectroscopic studies including 2D COSY, TOCSY, ROESY and heteronuclear 1H-31P and HMQC experiments it was established that the oligosaccharide has the following structure: [structure: see text].

Histological and immunohistochemical detection of different Helicobacter species in the gastric mucosa of cats

Detailed histopathological evaluation of the gastric mucosa of Helicobacter-infected cats is complicated by the difficulty of recognizing Helicobacter organisms on hematoxylin and eosin (HE)-stained sections and the ability of multiple Helicobacter species to infect cats. In this study, the presence and localization of different species of Helicobacter in the stomachs of cats was investigated using silver staining and immunohistochemistry. Five groups containing 5 cats each were established (group 1: urease negative and Helicobacter free; groups 2, 3, 4, and 5: urease positive and infected with Helicobacter heilmannii, unclassified Helicobacter spp., Helicobacter felis, and Helicobacter pylori, respectively). Gastric samples were evaluated by HE and silver staining and by immunohistochemistry with 3 different anti-Helicobacter primary antibodies. Helicobacter were detected by Steiner stain in all infected cats at the mucosal surface, in the lumen of gastric glands, and in the cytoplasm of parietal cells. In silver-stained sections, H. pylori was easily differentiated from H. felis, H. heilmannii, and unclassified Helicobacter spp., which were larger and more tightly coiled. No organisms were seen in uninfected cats. Helicobacter antigen paralleled the distribution of organisms observed in Steiner-stained sections for 2 of the 3 primary antibodies tested. The antisera were not able to discriminate between the different Helicobacter species examined. A small amount of Helicobacter antigen was present in the lamina propria of 3 H. pylori-, 3 H. felis-, and 1 H. heilmannii-infected cat. Minimal mononuclear inflammation was present in uninfected cats and in those infected with unclassified Helicobacter spp. and H. heilmannii cats. In H. felis-infected cats, lymphoid follicular hyperplasia with mild pangastric mononuclear inflammation and eosinophilic infiltrates were present. The H. pylori-infected cats had severe lymphoid follicular hyperplasia and mild to moderate mononuclear inflammation accompanied by the presence of neutrophils and eosinophils. These findings indicate that Steiner staining and immunohistochemistry are useful for detecting Helicobacter infections, particularly when different Helicobacter species can be present. Monoclonal antibodies specific for the different Helicobacter species could be important diagnostic aids. There appear to be differences in the severity of gastritis in cats infected with different Helicobacter species.

Multilocus sequence typing system for Campylobacter jejuni

The gram-negative bacterium Campylobacter jejuni has extensive reservoirs in livestock and the environment and is a frequent cause of gastroenteritis in humans. To date, the lack of (i) methods suitable for population genetic analysis and (ii) a universally accepted nomenclature has hindered studies of the epidemiology and population biology of this organism. Here, a multilocus sequence typing (MLST) system for this organism is described, which exploits the genetic variation present in seven housekeeping loci to determine the genetic relationships among isolates. The MLST system was established using 194 C. jejuni isolates of diverse origins, from humans, animals, and the environment. The allelic profiles, or sequence types (STs), of these isolates were deposited on the Internet (http://mlst.zoo.ox.ac.uk), forming a virtual isolate collection which could be continually expanded. These data indicated that C. jejuni is genetically diverse, with a weakly clonal population structure, and that intra- and interspecies horizontal genetic exchange was common. Of the 155 STs observed, 51 (26% of the isolate collection) were unique, with the remainder of the collection being categorized into 11 lineages or clonal complexes of related STs with between 2 and 56 members. In some cases membership in a given lineage or ST correlated with the possession of a particular Penner HS serotype. Application of this approach to further isolate collections will enable an integrated global picture of C. jejuni epidemiology to be established and will permit more detailed studies of the population genetics of this organism.

Identification of taxonomic and epidemiological relationships among Campylobacter species by numerical analysis of AFLP profiles

Amplified fragment length polymorphism (AFLP)-based profiling was performed on 138 strains representing all named Campylobacter species and subspecies. Profiles of 15/16 species comprised 6 to greater than 100 fragments and were subjected to numerical analysis. The mean similarity of 48 duplicate, outbreak and/or 'identical' strain profiles exceeded 94%. Species were clearly distinguished at the 17.90% similarity (S-) level in the dendrogram. Subspecies of Campylobacter jejuni and Campylobacter hyointestinalis, and biovars of Campylobacter lari and Campylobacter sputorum were distinguished at higher S-levels. All outbreak or 'genetically identical' strains of C. jejuni subsp. jejuni, Campylobacter coli, C. hyointestinalis and C. sputorum clustered at S-levels >92% and were distinguished from unrelated strains. Numerical analysis of AFLP profiles is useful for concurrent identification of taxonomic and epidemiological relationships among most Campylobacter species.

Epidemiology of ovine Campylobacter infection determined by numerical analysis of electrophoretic protein profiles

The relationship of 50 Campylobacter strains isolated from aborted ovine foetuses, and the faeces of sheep, cattle and chickens were determined by numerical analysis of electrophoretic (SDS-PAGE) protein profiles. Comparison of protein patterns by numerical methods revealed differences between C. fetus ssp. fetus, C. jejuni, and C. coli strains as well as heterogeneity among isolates from different outbreaks. Isolates from each farm produced a distinct cluster and flocks from different locations were found to be infected with relatively different strains. In most cases, protein patterns of ovine foetal isolates were very similar to those of ovine faecal isolates. Ovine isolates of C. fetus ssp. fetus, C. jejuni and C. coli gave similar protein patterns to the corresponding Campylobacter species isolated from cattle or chicken, on the same farm. Thus, it was concluded that certain protein types of ovine Campylobacter strains were more likely associated with local areas, and Campylobacter strains causing ovine abortions are distributed in the environment more widely than assumed to date.

Comparative fingerprinting analysis of Campylobacter jejuni subsp. jejuni strains by amplified-fragment length polymorphism genotyping

Amplified-fragment length polymorphism (AFLP) analysis with the endonucleases BglII and MfeI was used to genotype 91 Campylobacter jejuni subsp. jejuni strains from outbreaks and sporadic cases. AFLP-generated fragments were labeled with fluorescent dye and separated by capillary electrophoresis. The software packages GeneScan and GelCompar II were used to calculate AFLP pattern similarities and to investigate phylogenetic relationships among the genotyped strains. The AFLP method was compared with two additional DNA-based typing methods, pulsed-field gel electrophoresis (PFGE) using SmaI and restriction fragment length polymorphism analysis on PCR products (PCR-RFLP) of the flaA and flaB genes. We found that AFLP analysis of C. jejuni strains is a rapid method that offers better discriminatory power than do both PFGE and PCR-RFLP. AFLP and, to a lesser extent, PCR-RFLP could differentiate strains within the same PFGE profiles, which also makes PCR-RFLP an alternative to PFGE. We were able to clearly distinguish 9 of 10 recognized outbreaks by AFLP and to identify similarities among outbreak and sporadic strains. Therefore, AFLP is suitable for epidemiological surveillance of C. jejuni and will be an excellent tool for source identification in outbreak situations.

Efficacy of flagellin gene typing for epidemiological studies of Campylobacter jejuni in poultry estimated by comparison with macrorestriction profiling

Thirty isolates of Campylobacter jejuni isolated from 29 different Danish broiler flocks were chosen for the evaluation of PCR-Fla typing as a genotyping tool. Except for two isolates that originated from the same broiler flock, the isolates were clearly distinguishable on basis of their macrorestriction profiles using the restriction endonucleases SmaI and KpnI. PCR-Fla typing of the 30 isolates yielded 16 distinct genotypes, whereas one isolate was untypeable by this method. The dominant PCR-Fla type (1/1) was shared by eight isolates, and five additional Fla groups containing two or three isolates were obtained. The PCR-Fla type of one isolate changed spontaneously after five subcultures, illustrating the relative plasticity of the gene locus. Comparison of MRPs within and between Fla-types support the view that some PCR-Fla types may be conserved within clonal lines. It is concluded that PCR-Fla typing is useful as a genotyping tool in large-scale epidemiological studies but that additional analyses with other methods are required to properly define interstrain relationships.

Identification of Campylobacter jejuni, C. coli, C. lari, C. upsaliensis, arcobacter butzleri, and A. butzleri-like species based on the glyA gene

Currently, the detection and identification of Campylobacter and Arcobacter species remains arduous, largely due to cross-species phenotypic similarities and a relatively narrow spectrum of biochemical reactivity. We have developed a PCR-hybridization strategy, wherein degenerate primers are used to amplify glyA fragments from samples, which are then subjected to species-specific oligodeoxyribonucleotide probe hybridizations, to identify and distinguish between Campylobacter jejuni, C. coli, C. lari, C. upsaliensis, Arcobacter butzleri, and an A. butzleri-like species. Evaluation of this strategy with genomic DNA from different type strains suggests that this approach is both specific and sensitive and thus may be applicable in a diagnostic assay to identify and differentiate these highly related species.

Roles of the surface layer proteins of Campylobacter fetus subsp. fetus in ovine abortion

The role of the surface (S)-layer proteins of Campylobacter fetus subsp. fetus has been investigated using an ovine model of abortion. Wild-type strain 23D induced abortion in up to 90% of pregnant ewes challenged subcutaneously. Isolates recovered from both dams and fetuses expressed S-layer proteins with variable molecular masses. The spontaneous S-layer-negative variant, strain 23B, neither colonized nor caused abortions in pregnant ewes. A series of isogenic sapA and recA mutants, derived from 23D, also were investigated in this model. A mutant (501 [sapA recA(+)]) caused abortion in one of five challenged animals and was recovered from the placenta of a second animal. Another mutant (502 [sapA recA]) with no S-layer protein expression caused no colonization or abortions in challenged animals but caused abortion when administered intraplacentally. Mutants 600(2) and 600(4), both recA, had fixed expression of 97- and 127-kDa S-layer proteins, respectively. Two of the six animals challenged with mutant 600(4) were colonized, but there were no abortions. As expected, all five strains recovered expressed a 127-kDa S-layer protein. In contrast, mutant 600(2) was recovered from the placentas of all five challenged animals and caused abortion in two. Unexpectedly, one of the 16 isolates expressed a 127-kDa rather than a 97-kDa S-layer protein. Thus, these studies indicate that S-layer proteins appear essential for colonization and/or translocation to the placenta but are not required to mediate fetal injury and that S-layer variation may occur in a recA strain.

Isolation and characterization of Campylobacter jejuni subsp. jejuni from macaroni penguins (Eudyptes chrysolophus) in the subantarctic region

On Bird Island, South Georgia, albatrosses (n = 140), penguins (n = 100), and fur seals (n = 206) were sampled for Campylobacter jejuni. C. jejuni subsp. jejuni was recovered from three macaroni penguins (Eudyptes chrysolophus). These isolates, the first reported for the subantarctic region, showed low genetic diversity and high similarity to Northern Hemisphere C. jejuni isolates, possibly suggesting recent introduction to the area.

Integronlike structures in Campylobacter spp. of human and animal origin

Resistance to antimicrobial agents used to treat severe Campylobacter spp. gastroenteritis is increasing worldwide. We assessed the antimicrobial resistance patterns of Campylobacter spp. isolates of human and animal origin. More than half (n = 32) were resistant to sulphonamide, a feature known to be associated with the presence of integrons. Analysis of these integrons will further our understanding of Campylobacter spp. epidemiology.

Large-scale survey of Campylobacter species in human gastroenteritis by PCR and PCR-enzyme-linked immunosorbent assay

A PCR-based study of the incidence of enteropathogenic campylobacter infection in humans was done on the basis of a detection and identification algorithm consisting of screening PCRs and species identification by PCR-enzyme-linked immunosorbent assay. This was applied to DNA extracted from 3,738 fecal samples from patients with sporadic cases of acute gastroenteritis, submitted by seven regional Public Health Laboratories in England and Wales over a 2-year period. The sending laboratories had cultured "Campylobacter spp." from 464 samples. The PCR methodologies detected 492 Campylobacter-positive samples, and the combination of culture and PCR yielded 543 Campylobacter-positive samples. There was identity (overlap) for 413 samples, but 79 PCR-positive samples were culture negative, and 51 culture-positive samples were PCR negative. While there was no statistically significant difference between PCR and culture in detection of C. jejuni-C. coli (PCR, 478 samples; culture, 461 samples), PCR provided unique data about mixed infections and non-C. jejuni and non- C. coli campylobacters. Mixed infections with C. jejuni and C. coli were found in 19 samples, and mixed infection with C. jejuni and C. upsaliensis was found in one sample; this was not apparent from culture. Eleven cases of gastroenteritis were attributed to C. upsaliensis by PCR, three cases were attributed to C. hyointestinalis, and one case was attributed to C. lari. This represents the highest incidence of C. hyointestinalis yet reported from human gastroenteritis, while the low incidence of C. lari suggests that it is less important in this context.

Drug resistance in Campylobacter jejuni, C coli, and C lari isolated from humans in north west England and Wales, 1997

AIMS

To test the sensitivity of strains of Campylobacter species isolated from humans in England and Wales against a range of antimicrobial agents for the purpose of monitoring therapeutic efficacy and as an epidemiological marker.

METHODS

An agar dilution breakpoint technique was used to screen isolates against ampicillin, chloramphenicol, gentamicin, kanamycin, neomycin, tetracycline, nalidixic acid, ciprofloxacin, and erythromycin. Minimal inhibitory concentrations (MIC) were also determined for a sample of quinolone resistant strains.

RESULTS

Approximately 50% of strains tested were resistant to at least one drug. Strains which were resistant to four or more of the drugs tested were classified as multiresistant; this occurred in 11.3% of C jejuni, 19.9% of C coli, and 63.6% of C lari. Resistance to erythromycin occurred in 1.0% of C jejuni and 12.8% of C coli. Resistance to quinolones occurred in 12% of strains, with a ciprofloxacin MIC of > 8 mg/l and a nalidixic acid MIC of > 256 mg/l; a further 4% of strains had intermediate resistance with a ciprofloxacin MIC of between 0.5 and 2 mg/l (fully sensitive strains, 0.25 mg/l or less) and a nalidixic acid MIC of between 32 and 64 mg/l (fully sensitive strains, 8 mg/l or less).

CONCLUSIONS

Resistance to quinolones in campylobacters from human infection may relate to clinical overuse or use of fluoroquinolones in animal husbandry. Both veterinary and clinical use should be reconsidered and fluoroquinolone drugs used only as a treatment for serious infections requiring hospital admission. Erythromycin resistance is still rare in C jejuni but much more common in C coli.

Campylobacter species in cats and dogs in South Australia

BACKGROUND

Campylobacter enteritis was the most frequently notified infectious disease in Australia in 1996 and Campylobacter species have been associated with extra-intestinal infections such as purulent arthritis and Guillian-Barré syndrome. Dogs and cats are known to carry campylobacteria and contact with household pets have been implicated as possible sources of human infection.

OBJECTIVE

To provide information on the species of campylobacter carried by cats and dogs in South Australia.

METHODS

Faecal samples were collected from stray and owned cats and dogs and feral cats. Campylobacter-like organisms were isolated using selective media and filtration methods. They were then characterised by biochemical tests, antibiotic resistance and growth patterns under various conditions. Husbandry factors that could have influenced the carriage rates were examined both as single variables and in a multivariate logistic regression.

RESULTS

Campylobacter upsaliensis and C jejuni were found in 11% and 4% of cats, respectively, whereas 34% dogs carried C upsaliensis, 7% C jejuni and 2% C coli. Intensive housing and open drains were found to be significant risk factors and increased the carriage rate by 2 and 2.6 times, respectively.

CONCLUSION

Dogs and cats are a potential reservoir for human enteric infections with campylobacters.

High-resolution genomic fingerprinting of Campylobacter jejuni and Campylobacter coli by analysis of amplified fragment length polymorphisms

A method for high-resolution genomic fingerprinting of the enteric pathogens Campylobacter jejuni and Campylobacter coli, based on the determination of amplified fragment length polymorphism, is described. The potential of this method for molecular epidemiological studies of these species is evaluated with 50 type, reference, and well-characterised field strains. Amplified fragment length polymorphism fingerprints comprised over 60 bands detected in the size range 35-500 bp. Groups of outbreak strains, replicate subcultures, and 'genetically identical' strains from humans, poultry and cattle, proved indistinguishable by amplified fragment length polymorphism fingerprinting, but were differentiated from unrelated isolates. Previously unknown relationships between three hippurate-negative C. jejuni strains, and two C. coli var. hyoilei strains, were identified. These relationships corresponded to available epidemiological data. We conclude that this amplified fragment length polymorphism fingerprinting method may be a highly effective tool for molecular epidemiological studies of Campylobacter spp.

Intermittent shedding of thermophilic campylobacters by sheep at pasture

The rates at which sheep on different types of pasture shed campylobacters in their faeces were measured over 12 months. Overall, shedding of campylobacters at pasture was between a third and a half of the carriage rate (92%) of the intestines of sheep at slaughter. Shedding was highest during saltmarsh grazing, followed by upland fell and farm grazing. The rate of shedding varied at different times of the year, with the highest rates (100%) coinciding with lambing, weaning, and movement onto new pasture. The lowest rates (0%) occurred when sheep were fed on hay and silage. On the farm, low rates occurred during the whole of gestation, both when the sheep were indoors and outdoors. Campylobacter jejuni was the main species isolated and survived for up to 4 d in sheep faeces. Lambs became colonized by Campylobacter within 1-5 d of being born. Ewes, which were not shedding campylobacters prior to lambing, started to shed after lambing, and ewes which were shedding low numbers of Campylobacter before lambing, increased the numbers of bacteria being shed after lambing.

In vitro genotypic variation of Campylobacter coli documented by pulsed-field gel electrophoretic DNA profiling: implications for epidemiological studies

Six isolates of Campylobacter coli from different pig herds were subcultured up to 50 times over a 6-month period and DNA samples suitable for pulsed-field gel electrophoretic (PFGE) profiling prepared at regular (1, 20, 40 and 50 passages) intervals. In 5/6 strains, changes in the banding patterns of Sma1, Sal1 and/or BamH1 digests were observed. In one such strain the differences were considered artifactual. However, significant alterations in PFGE profiles between subcultures of four strains were seen, irrespective of the restriction enzyme used. Spontaneous intramolecular genomic rearrangements were considered the most likely mechanism for the changes observed. A numerical analysis based upon the combined distribution of Sma1- and sal1-derived fragments clustered most strain subcultures together, with the exception of those from one isolate which were divided into two clusters. The effect of spontaneous genetic change on PFGE profiles must be considered when evaluating strain relationships. Numerical techniques may aid data interpretation but results must be evaluated cautiously.

16S rRNA gene sequences of 'Candidatus Campylobacter hominis', a novel uncultivated species, are found in the gastrointestinal tract of healthy humans

Although some Campylobacter species are agents of gastroenteritis and periodontal disease in humans, little is known of the variety of campylobacters in the gastrointestinal tract of healthy individuals. This paper provides evidence for the existence of a previously undescribed, uncultivated Campylobacter species that may be a commensal in the healthy human gut. Saliva and faeces from 20 healthy individuals were examined by PCR assays specific for nine species of campylobacter (C. sputorum, C. concisus, C. upsaliensis, C. helveticus, C. lari, C. fetus, C. hyointestinalis, C. jejuni and C. coli) and for the genus as a whole. Genus-specific amplicons were produced from 19 of 20 saliva samples and from 18 of 20 faecal samples. C. concisus species-specific amplicons were produced from 19 of 20 saliva samples and 3 of 20 faecal samples. The faecal samples were all PCR-negative for other Campylobacter species. Three unidentified 16S rRNA Campylobacter genus-specific amplicons of faecal origin were sequenced. Phylogenetic analysis showed that these sequences were 99% similar, and clustered within the genus as a novel group which was termed HS (HS = healthy subject). A PCR primer pair specific for the HS group was designed from the sequence data and used to reexamine the original samples. Although it was not possible to culture the organism from faeces, specific PCR assay detected it in 10 of the 20 faecal samples, but not in any corresponding saliva samples. The authors propose that the source of the amplicons is a previously undescribed and so far uncultivated species, which they term 'Candidatus Campylobacter hominis'.

Evaluation of a new arcobacter enrichment medium and comparison with two media developed for enrichment of Campylobacter spp

The productivity of an arcobacter enrichment medium (AM), newly developed by Oxoid was compared with two campylobacter enrichment media (Preston broth (Oxoid) and LabM broth), with arcobacter basal medium (ABM) as control. Twenty strains of Arcobacter and Campylobacter spp. were tested for growth, with target inocula of < 4 cfu per ml of medium. Incubation was carried out aerobically for 48 h with tightly closed caps at 25 degrees C for arcobacters and 37 degrees C for campylobacters. After incubation the numbers of cfu in the broths were counted by surface-plating on blood agar. None of the Campylobacter spp. grew in the complete AM, and only one grew (very poorly) in the arcobacter basal medium. However, AM supported good growth of all three species of Arcobacter (A. butzleri, A. skirrowii and A. cryaerophilus) which have been associated with human and animal disease. The one strain of A. nitrofigilis tested failed to grow in any of the media except poorly in ABM. None of the Arcobacter spp. grew in Preston Broth, but nine grew in LabM broth, although productivity was poor compared to AM. None of the Campylobacter spp. grew in AM and only one grew (very poorly) in ABM.

An outbreak of infectious hepatitis in commercially reared ostriches associated with Campylobacter coli and Campylobacter jejuni

A disease causing high morbidity and mortality was observed in young ostriches from six properties in southeast Queensland, Australia. The disease affected birds from 2-8 weeks of age and was characterised clinically by bright-green urates and pathologically by severe necrotic hepatitis. The liver lesions resembled those of vibrionic hepatitis in other avian species. Campylobacter coli was isolated from the livers of affected ostriches from five of the six properties. Campylobacter jejuni subsp. jejuni was isolated from birds from the remaining property. Pulsed-field gel electrophoresis-based (PFGE) typing of representative isolates indicated that trade of infected birds between farms was an important factor in the spread of C. coli. Phenotypic and genotypic data suggest a clonal variant of the principal outbreak type may account for the remaining cases from which C. coli was found. Conventional biochemical test results and PFGE clearly distinguished the C. jejuni strain isolated from the geographically remote farm from the outbreak of C. coli type. We believe this to be the first definitive report of avian hepatitis associated with C. coli.

Evaluation of a PCR assay for identification and differentiation of Campylobacter fetus subspecies

OBJECTIVE

To evaluate a polymerase chain reaction assay for identification of Campylobacter fetus and differentiation of the defined subspecies.

DESIGN

Characterisation of bacterial strains by traditional phenotyping, polymerase chain reaction, a probabilistic identification scheme and macrorestriction profiling using pulsed field gel electrophoresis.

PROCEDURE

The results of identification of 99 bacterial strains as determined by conventional phenotyping or by polymerase chain reaction were compared. Two of these were type strains of C fetus subsp fetus and C fetus subsp venerealis; the remaining strains were field isolates putatively identified as C fetus. In cases where the subspecies identity was disputed, isolates were identified by means of a probabilistic identification scheme and by macrorestriction profiling.

RESULTS

The agreement between strain identities initially suggested by traditional phenotypic methods and the PCR assay was found to be 80.8%. The polymerase chain reaction proved to be a reliable technique for the species and subspecies identification of C fetus; equivocal results were obtained in only two instances. Initial misidentifications by conventional phenotyping methods were attributed to methodological differences used in various laboratories.

CONCLUSION

Our results indicate that misidentification of C fetus in routine diagnostic laboratories may be relatively common. The PCR assay evaluated gave rapid and reproducible results and is thus a valuable adjunctive method for the identification of C fetus and subsequent subspecies differentiation.

A probability matrix for the identification of campylobacters, helicobacters and allied taxa

A probabilistic identification matrix for campylobacteria, comprising 76 phenotypic characters and 37 taxa, is described. The accuracy and integrity of the matrix was evaluated using established computer-assisted methods. Certain taxa (for example, Campylobacter concisus and Camp. gracilis) demonstrated significant phenotypic diversity; previous data corroborated these findings. Differentiation between a few pairs of taxa proved difficult, although discriminatory characteristics were noted in each of these cases. The results indicate that most campylobacteria can be identified accurately and objectively with phenotypic tests when probabilistic methods of data assessment are employed.

Repetitive and arbitrary primer DNA sequences in PCR-mediated fingerprinting of outbreak and sporadic isolates of Campylobacter jejuni

PCR-mediated fingerprinting with combined repetitive and arbitrary DNA primers (ERIC-2 and 1026) was used to type Campylobacter jejuni from a milk-associated outbreak, and from sporadic cases of the same and allied HS serotypes. The 14 outbreak strains had identical or similar DNA band profiles whereas the 25 strains from sporadic infections were more heterogeneous with 18 different DNA profiles. Although PCR-based DNA fingerprints lacked serotype specificity, the method was fast, simple to perform and reproducible, provided defined technical protocols were adhered to precisely. Profiles were highly discriminatory but did not consistently match types based on other molecular methods. We conclude that AP-PCR has demonstrable potential for initial rapid investigation of outbreaks, and when used in conjunction with PFGE analysis of DNA restriction profiles, provides a high resolution strategy for accurately defining subtypes of C. jejuni.

Prevalence of Helicobacter-like organisms in porcine gastric mucosa: a study of swine slaughtered in Italy

Recent reports described some cases of gastritis in man caused by an uncultured gram-negative spiral bacterium morphologically identical to organisms observed in the stomachs of mammalians (e.g. cats, dogs, pigs). The aim of the present study is to confirm the presence of these bacteria in Italian swine. Tightly spiralled organisms (Gastrospirillum suis) were found in the stomach of eight (9.4%) out of 85 pigs examined. The bacteria were always associated with macroscopic lesions indicative of gastritis. Attempts to culture H. pylori or Helicobacter-like organisms were unsuccessful. The possibility that Gastrospirillum may be a zoonotic pathogen, with transmission occurring from pigs to humans, is discussed.

Rapid identification of Campylobacter species by restriction fragment length polymorphism analysis of a PCR-amplified fragment of the gene coding for 16S rRNA

Restriction fragment length polymorphism analysis of a PCR-amplified DNA fragment of the gene coding for 16S rRNA was performed on 148 previously characterized strains of Campylobacter, Helicobacter, Arcobacter, and Wolinella succinogenes and 13 Campylobacter-like isolates. These strains included clinical, animal, and environmental isolates. PCR amplification generated a 283-bp fragment from all species. The amplicon from each strain was digested with six restriction endonucleases (AccI, AvaI, DdeI, HaeIII, HpaII, XhoI). DdeI was useful for the initial grouping of the strains. Additional discrimination within the different DdeI groups was obtained with AccI, HaeIII, HpaII, and XhoI digestions. The PCR-restriction fragment length polymorphism analysis allowed for the discrimination of members of the genus Campylobacter from members of closely related genera and discrimination between Campylobacter species. The proposed method is simple and rapid and can be useful for the routine identification of Campylobacter-like organisms in clinical or epidemiologic studies.