Campylobacter immunity and coinfection following a large outbreak in a farming community.

An outbreak of campylobacteriosis affected approximately one-half of 165 people attending an annual farmers' dance in Montrose, Scotland, in November 2005. Epidemiological investigations, including a cohort study (n = 164), identified chicken liver paté as the most likely vehicle of infection. Paté preparation involved deliberate undercooking of chicken livers by flash-frying, followed by mechanical homogenization. Typing of 32 Campylobacter strains (isolated from submitted stools) by multilocus sequence typing identified four distinct clades of Campylobacter jejuni. There was good agreement when isolates were typed by Penner serotyping, pulsed-field gel electrophoresis, and flaA short variable region sequencing but poorer agreement with phage and antibiotic susceptibility testing. At least three attendees were coinfected with two Campylobacter strains each. The outbreak was probably due to several livers contributing Campylobacter strains that survived undercooking and were dispersed throughout the paté. The study highlights improper culinary procedures as a potential human health risk and provides a striking counterexample to the "dominant outbreak strain" view of point source outbreaks of food-borne infections. It also demonstrates that previous exposure to biologically plausible sources of Campylobacter may confer protection against subsequent infection.

Persistence of Campylobacter species, strain types, antibiotic resistance and mechanisms of tetracycline resistance in poultry flocks treated with chlortetracycline.

OBJECTIVES: The aim of this study was to investigate the persistence of Campylobacter species, strain types, antibiotic resistance and mechanisms of tetracycline resistance in poultry flocks treated with chlortetracycline. METHODS: Three commercially reared broiler flocks, naturally colonized with Campylobacter, were treated with chlortetracycline under experimental conditions. The numbers of Campylobacter isolated, and the species, flaA short variable region allele, and antimicrobial resistance of isolates were determined. RESULTS: For two of three flocks, tetracycline-resistant strains predominated prior to chlortetracycline exposure. Presence of the antibiotic had no discernible effect on the numbers or types of Campylobacter and the tetracycline-resistant strains persisted in numbers similar to those observed before treatment. With all flocks, some faecal samples were obtained that contained no Campylobacter, irrespective of exposure to chlortetracycline; this was more common as the birds grew older. For the third flock, tetracycline-resistant Campylobacter were in the minority of samples before and during exposure to chlortetracycline, but at sampling times after this, no resistant strains were found in the treated (or untreated) birds, irrespective of exposure to the antibiotic. All tetracycline-resistant isolates (MICs 16 to >128 mg/L) contained tet(O) and, for some isolates, this was transferable to Campylobacter jejuni 81116. The efflux pump inhibitor PAbetaN reduced the MICs of tetracycline for these isolates by 4-fold, suggesting that an intact efflux pump, presumably CmeABC, is required for high-level tetracycline resistance. CONCLUSIONS: Our data indicate that chlortetracycline treatment does not eradicate tetracycline-resistant Campylobacter spp. from poultry. However, if a low number of resistant isolates are present, then the antibiotic pressure appears insufficient to select such strains as the dominant population.

Campylobacter and Salmonella in raw red meats in the United Kingdom: prevalence, characterization and antimicrobial resistance pattern, 2003-2005.

The prevalence of Campylobacter and Salmonella was assessed in 3959 raw red meats in the UK during 2003-2005. Meats were more frequently contaminated with Campylobacter (7.2%) than with Salmonella (2.4%). Lamb and other meats (e.g. mutton, rabbit) exhibited the highest contamination from Campylobacter (12.6% and 19.8%, respectively), compared with pork (6.3%) and beef (4.9%). Pork however had the highest contamination from Salmonella (3.9%), followed by lamb (2.0%), other meats (2.0%) and beef (1.3%). Offal samples (36.6%) were more frequently contaminated with Campylobacter or Salmonella than muscle tissue (7.0%). C. jejuni predominated in all meat types. C. coli isolates were more likely to exhibit antimicrobial drug resistance, including quinolones, than C. jejuni. Salmonella typhimurium was the most frequent Salmonella serotype isolated from meats; S. typhimurium DT104/104b isolates exhibited higher rates of multiple drug resistance than other serotypes. The findings reinforce the importance of adequate cooking of meat and good hygiene to avoid cross-contamination.

Comparison of virulence-associated in vitro properties of typed strains of Campylobacter jejuni from different sources.

Campylobacter jejuni is a major cause of human diarrhoeal disease, but specific virulence mechanisms have not been well defined. This blinded study was undertaken with 40 C. jejuni isolates from different sources to determine their haemolytic, cytotoxic and adhesion and invasion activities towards mammalian cells. The results were correlated with source of isolation and genetic makeup by amplified fragment length polymorphism (AFLP) typing. The isolates had variable degrees of haemolytic activity against rabbit erythrocytes and cytotoxicity towards CaCo-2, HeLa and Vero cells. The data indicated that the haemolytic and cytotoxic activities were due to separate factors. A range of cytotoxicity was exhibited, whereby some strains had no activity against the target cells and others had activity against all three cell lines. Certain strains had activity against CaCo-2 cells but little or no activity against the other cells, while others exhibited the opposite phenotype. The data suggested that the cytotoxicity assay with the different cell lines may have detected more than one cytotoxin. A wide variation between isolates was observed for both adherence and invasion with all three cell lines, yet, overall, the strains showed a significantly greater invasion capacity for CaCo-2. There was no clear relationship between source of isolation or disease manifestation and possession of statistically significantly higher levels of particular virulence-associated factors although, in some cases, a correlation between cytotoxicity and cell invasion was evident. Five AFLP clusters, each representing two to eleven isolates with similar profiles, were observed at the 90 % similarity level. Some AFLP groups contained isolates with a common serotype, but each group had C. jejuni isolates from more than one source with the exception of group IV, which contained only human isolates. Isolates with high cytotoxic activity against CaCo-2 cells were confined to groups I, III and IV and a group of unrelated strains (U). Group II isolates had uniformly low cytotoxicity. Isolates in groups I, V and U were more invasive for CaCo-2 cells than isolates in groups II, III and IV. The strain differences in cytotoxicity or invasion did not correlate with source of isolation.

Surveillance of primary antibiotic resistance of Helicobacter pylori at centres in England and Wales over a six-year period (2000-2005).

Antibiotic resistance is a key factor in the failure of Helicobacter pylori eradication therapy, yet few sentinel schemes exist to monitor trends in resistance at local, national or international levels. This study aimed, over a six-year period, to monitor resistance levels of H. pylori in England and Wales to the four antibiotics used in its treatment. A total of 1,310 isolates from Gwynedd in north Wales and from mid-Essex in south-east England were collected from 2000 to 2005 and tested for susceptibilities to metronidazole, clarithromycin, amoxicillin and tetracycline. Overall, metronidazole and clarithromycin resistance rates were 28.6% and 8.3% in Gwynedd and significantly higher (36.3%, p=0.0031, and 12.7%, p=0.0112) in mid-Essex. Rates of resistance to metronidazole and clarithromycin increased in both areas over this six-year period. Resistance rates were higher in female compared with male patients (38.1% vs 26.6% for metronidazole, p<0.0001, and 12.9% vs 7.5% for clarithromycin, p=0.0024), and were higher in patients <45 years compared with those ?45 years (44.0% vs 29.0% for metronidazole, p=0.0002, and 15.0% vs 9.4% for clarithromycin, p=0.0233). This study highlights the importance of antibiotic resistance surveillance in H. pylori for providing information on local resistance rates for test and treat strategies.

Culture of Helicobacter pylori from domestic water samples--the impact of strain variation on growth on solid and in liquid media.

Helicobacter pylori is an important global human pathogen and there is growing evidence from PCR assays that contaminated drinking water might be a possible source of infection in some circumstances. There are no validated protocols for direct isolation but various culture media have been developed for possible environmental sampling. Our aim here was to investigate how inter-strain variation might affect the interpretation of results with such media. Two laboratory adapted reference strains and four recent clinical isolates were tested on four solid media and in ten liquid media. Considerable variation was found between strains in their ability to recover on the different media after stress exposure (suspension in sterile tap water). Generally, clinical isolates were less robust than the laboratory-adapted strains and, overall, the former required longer recovery times. Our findings highlighted the importance of using a range of isolates for evaluations, as examination of laboratory-adapted strains alone did not provide an accurate representation of the utility of media that may be used to recover H. pylori from water.

Screening the human protocadherin 8 (PCDH8) gene in schizophrenia.

Abnormalities in synaptic connectivity and plasticity have been implicated in the pathophysiology of schizophrenia. Molecules involved in the development and maintenance of neural circuitry include the recently cloned protocadherins. Human protocadherin 8 (PCDH8) is homologous to 'arcadlin', a molecule shown to play a role in hippocampal synaptic function in the rat. The gene encoding PCDH8 maps to a region on chromosome 13 where linkage to schizophrenia has been reported. In this study, the entire expressed sequence of the PCDH8 gene and over 800 bp of the 5' flanking region were screened for polymorphisms in 30 DSM-IV schizophrenia individuals using Denaturing High Performance Liquid Chromatography (DHPLC). A total of nine single nucleotide polymorphisms were identified, including three in the first exon that are predicted to change the amino acid sequence. One polymorphism, causing the Trp7Arg change in the putative signal peptide, showed a trend towards excess of the arginine encoding allele in a case-control sample consisting of 520 DSM-IV schizophrenia patients and 535 matched controls from the UK (chi2=3.72, P [1 df]= 0.054). However, this polymorphism did not show preferential transmission to schizophrenic individuals in a separate sample of 203 proband-parent trios from Bulgaria. A second, rare single nucleotide variation, predicting the non-conservative amino acid change Glu39Ala, was found in one schizophrenic individual and their affected sibling but not in a further 352 affected individuals, nor 357 controls. These results suggest that any contribution of PCDH8 polymorphisms to schizophrenia susceptibility is likely to be weak, although the existence of rare variations of stronger effect cannot be excluded.

Sequence similarities between large subunit ribosomal RNA gene intervening sequences from different Helicobacter species.

When the 23S rRNA genes from several Helicobacter species were amplified by PCR and compared with similar amplicons derived from H. pylori, they were seen to be enlarged in size. Sequencing of these enlarged genes from H. mustelae, H. canis (two strains) and H. muridarum identified insertions of novel sequence (intervening sequences, IVSs) sized between 93 and 377 bp located at nt 545, in place of an 8-nt sequence in the conventionally sized H. pylori gene. These IVSs were not present elsewhere in the genome. All strains with such IVSs lacked intact 23S rRNA which was replaced by two fragment whose sizes were consistent with cleavage at either side of the particular IVS. The predicted secondary structures of the four IVSs were characterised by base pairing at the 5' and 3' ends to form a stem. The four IVSs exhibited significant sequence inter-relationships. Further relationships were also observed between them and similar elements in both small and large subunit rRNA genes of other Helicobacter and Campylobacter species. Alignment of each IVS with the other such elements identified blocks of related sequence consistent with insertion/deletion events, indicating possible evolutionary relationships.

Rapid identification by PCR of the genus Campylobacter and of five Campylobacter species enteropathogenic for man and animals.

The nucleotide sequences for the 16S ribosomal RNA gene were compared for 33 species comprising the epsilon subdivision of the Proteobacteria (genera: Campylobacter, Helicobacter, Arcobacter and Wolinella). Regions specific for the genus Campylobacter and for five Campylobacter species important in human and/or veterinary medicine were identified. From these regions, PCR primer pairs were designed for use in species-specific identification. Primer pairs were validated against strains representing all taxa of campylobacter-like organisms. They did not amplify products other than from their five target species (C. upsaliensis, C. helveticus, C. fetus, C. hyointestinalis and C. lari), and they generated amplicons of defined size from large numbers of strains of those species. A primer pair suitable for identification of the genus Campylobacter was also identified and validated. This generated amplicons from all species of Campylobacter as well as from unnamed groups known to be within the genus, but not from any species or unnamed strains of Helicobacter, Arcobacter or Wolinella.

Flagellin gene profiling of Campylobacter jejuni heat-stable serotype 1 and 4 complex.

Flagellin gene (flaA) sequence polymorphisms were used to discriminate amongst 167 strains of Campylobacter jejuni serotype HS1 and the HS4 complex. Direct PCR of cell suspensions provided a rapid method for analysing DNase-negative strains, whereas purified DNA was necessary for the DNase-positive strains. Nine different PCR-RFLP patterns (genotypes) were identified by analysis with Hinfl and 12 with Ddel, giving a total of 19 combined flaA profile types. The most common combined fla types were H1D1 (35%) and H1D2 (20%) for serotype HS1, and H1D2 (23%) and H4D7 (43%) for serotype HS4. Comparison of flaA typing with other key subtyping methods for C. jejuni showed it to be less discriminatory than pulsed field gel electrophoretic (PFGE) profiling, but more so than ribotyping. Fla types provided a useful indication of strain diversity, but as some were conserved across different serotypes, ribotypes and PFGE types, the same fla type could not be used as the sole basis for grouping strains. We provide evidence for several distinct subgroups based on conserved multiple genomic criteria within the HS1 and HS4 strains, and conclude that monitoring of such subgroups could provide a novel basis for future epidemiological surveillance of C. jejuni.

Molecular typing of thermotolerant species of Campylobacter with ribosomal RNA gene patterns.

Ribosomal RNA gene restriction patterns (ribopatterns) of 72 strains representing Campylobacter jejuni (subspecies jejuni and doylei), C. coli, C. upsaliensis and C. lari including the urealytic (UPTC) biovar were determined using four common restriction endonucleases (HaeIII, HindIII, PstI and PvuII). The relative effectiveness of these enzymes for general molecular typing of the thermotolerant campylobacters was assessed. Ribotypes (HaeIII) were defined on the basis of computer-assisted numerical analysis. For C. jejuni, C. coli and C. lari, the HaeIII ribopatterns provided a high level of typability and discrimination, with patterns that were reproducible and easy to code for numerical analysis. There was evidence of diversity within three of the HaeIII types, and PstI ribopatterns proved the most reliable for detecting such differences. C. upsaliensis also could be ribotyped with HaeIII, but HindIII, PvuII and PstI were less satisfactory for this species. For such campylobacters, the HindIII ribopatterns generally were complex and difficult to compare, and the PvuII profiles provided the least discrimination. We conclude that the choice of restriction endonuclease is of critical importance when applying ribotyping to different species of Campylobacter. HaeIII ribopatterns were the most effective means of typing strains of different thermotolerant species of campylobacters and, when combined with PstI ribopatterns, offered a highly discriminatory basis for molecular typing.

Flagellin gene profiling of Helicobacter pylori infecting symptomatic and asymptomatic individuals.

Diversity within and around the flagellin (fla) A gene of Helicobacter pylori was studied by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) analysis and genomic Southern blot hybridization profiling. Four distinct pattern types were identified by DdeI restriction analysis of the 1.5-kb flaA amplicon of 55 strains. Most strains (73%) had the same flaA RFLP type, but subtypic variation was evident in some strains. No consistent associations were observed for selected strain subsets between the DdeI flaA profiles and phenotype (motility and cytotoxicity), urease gene profile or patient symptomatology. A subset of seven (F-1 profile) and four (F-2 profile) strains with identical HindIII digest patterns provided further evidence that the flaA gene was relatively highly conserved within H. pylori. By contrast, the flaA gene blot hybridization profiles were more diverse and consistent with greater variation at restriction sites in adjacent regions of the genome. We conclude that analyses of polymorphisms within the flaA gene provide limited discrimination between strains of H. pylori. The flaA genomic blot profiles offer greater potential for molecular typing purposes, although no associations with other pathogenicity factors or disease symptoms could be deduced.

Random amplified polymorphic DNA fingerprinting of Campylobacter jejuni and C. coli isolated from human faeces, seawater and poultry products.

The polymerase chain reaction (PCR) technique was used to obtain randomly amplified polymorphic DNA (RAPD) profiles from 64 type and serotype reference strains and 114 isolates of Campylobacter jejuni and C. coli from food, seawater and human faeces. Genetic diversity was detected among the strains as a total of 118 different RAPD profiles were obtained, each one containing from 4 to 11 bands between 0.30 and 1.50 kb. The discriminatory power of a random 10-mer primer (sequence 5'-CAATCGCCGT-3') was assessed. In general, no profiles were common to strains of the same Penner serogroup, but occasional strains from different Penner serotypes shared identical band profiles. RAPD analysis also differentiated between the species, and after numerical analysis, five main clusters were defined at the 40% similarity level, corresponding to C. jejuni, C. coli and C. lari with some exceptions. RAPD profiling of Campylobacter is highly discriminatory and is a valuable new alternative to traditional typing in epidemiological studies.

Evaluation of Helicobacter species in inflammatory bowel disease.

BACKGROUND: Bacteria have been implicated in the pathogenesis of inflammatory bowel disease. Helicobacter species have been shown to cause colitis in animal models and have been identified in human diarrhoeal illness and Crohn's disease. AIM: To determine whether Helicobacter species are present in human inflammatory bowel disease tissue. METHODS: Thirty patients undergoing colonoscopy for clinical reasons were studied. Nine had Crohn's disease, 11 had ulcerative colitis and 10 had histologically normal colons. Tissue was snap-frozen at -70 degrees C. DNA was extracted and examined by five different polymerase chain reaction (PCR) assays that were either genus or species specific for Helicobacter. RESULTS: Analyses of colonic biopsies by two Helicobacter genus-specific PCR assays, two H. pylori-specific assays and a PCR assay designed to amplify fragments of 'H. heilmannii'-like organisms demonstrated that product was not generated by any test. Internal control PCR demonstrated that PCR results for the five assays were not negative due to the presence of residual substances inhibitory to PCR. CONCLUSIONS: Helicobacter species were not identified in this study, using multiple PCRs to eliminate the problems of non-specific cross-reaction. This suggests that Helicobacter species do not play a role in the pathogenesis of inflammatory bowel disease.

The effect of omeprazole dosing on the isolation of Helicobacter pylori from gastric aspirates.

BACKGROUND: Animal experiments suggest that omeprazole dosing increases shedding of Helicobacter into the gastric lumen, and hence into gastric juice. AIM: To assess the effect of omeprazole dosing on the yield of H. pylori from gastric aspirates of infected volunteers. METHODS: Six serial nasogastric aspirates, three before and three during dosing with omeprazole 40 mg b.d., were obtained for culture from 10 H. pylori infected volunteers and one uninfected volunteer. To reduce contamination, samples were diluted 1:10 with Maximum Recovery Diluent (MRD; pH 7.0) or HCl-KCl buffer (pH 2.2) prior to culture on Columbia and Dent's agar. RESULTS: Undiluted gastric juice cultures were rapidly overgrown by upper respiratory tract flora. HCl-KCl dilution resulted in isolation of H. pylori from 77% of infected subject aspirates before, and 67% of aspirates during dosing with omeprazole. The yields were significantly lower with MRD dilution, 47% and 10%, respectively. Omeprazole dosing significantly decreased the yield after MRD dilution, but not after HCl-KCl dilution. CONCLUSIONS: Decreasing intragastric acidity, by dosing with omeprazole, decreases the isolation of H. pylori from routinely processed gastric aspirates. In vitro acidification of gastric aspirates, by HCl-KCl dilution, increases the isolation of H. pylori both before and during omeprazole dosing.

Flavobacterium meningosepticum from cases of meningitis in Botswana and England.

Two strains of Flavobacterium meningosepticum isolated from cases of meningitis are described. One was isolated in Botswana from a man with an aplastic anaemia, the other in the UK from an infant who was probably infected in Bangladesh. The severity of the infection, the characterization of the organism, and the possibility that infection may be found in the UK are discussed.

DNA fingerprints of Helicobacter pylori before and after treatment with omeprazole.

AIMS: To test whether a hypoacidic environment may potentially "stress" Helicobacter pylori DNA, encouraging the emergence of strain variation. METHODS: This hypothesis was tested by inducing prolonged hypoacidity with omeprazole, a potent antisecretory drug. The genomic DNA of H pylori was studied by electrophoretic separation of restriction endonuclease fragments followed by rRNA gene hybridisation in seven patients infected with H pylori before and after treatment with omeprazole 20-40 mg daily for six to eight weeks. DNA was isolated and purified using the guanidium thiocyanate reagent method. DNA samples were digested with Hae III, electrophoresed, vacublotted, and hybridised using a biotinylated cDNA probe prepared from 16S and 23S rRNA from H pylori NCTC 11638. Isolates were compared using their ribopatterns (DNA fingerprints). RESULTS: A total of 26 isolates were obtained; all DNA isolates were cut by Hae III, which was the enzyme that gave the best resolved hybridisation patterns for analysis. No two patients harboured the same strain. The isolates from two patients showed evidence of subtypic variation; one patient had two distinct strains and four patients had their own indistinguishable strains before and after treatment with omeprazole. For each patient, the paired ribopatterns of H pylori DNA were not affected by treatment with omeprazole for six to eight weeks. CONCLUSION: The H pylori genome is relatively stable when exposed to the conditions of prolonged hypoacidity that result from treatment with omeprazole.

Signature patterns of DNA restriction fragments of Helicobacter pylori before and after treatment.

The genomic DNA of Helicobacter pylori was studied by electrophoretic analysis of restriction endonuclease fragments. Twenty seven isolates from eight patients in the United Kingdom, obtained before and after treatment with nitrofurantoin, and two reference strains from Australia and Peru were investigated. Digestion of DNA with HaeIII, which gave the clearest band pattern of the 20 enzymes tested, showed that each set of isolates from a single patient had a unique band pattern. The DNA signature band patterns of strains from different patients were less than or equal to 62% similar (average 43%); similarities of patterns from the same patient were generally greater than or equal to 86%. Some minor but reproducible polymorphisms (less than or equal to five bands) in the signature region were detected in most consecutive isolates. Plasmid DNA was detected in isolates from five patients, but major pattern differences were attributed to genomic variation. It is concluded that the HaeIII DNA digest signature fingerprints provide a reproducible and sensitive method of discriminating between isolates of H pylori.