Campylobacter hyointestinalis associated with human gastrointestinal disease in the United States

Application of TraDIS to define the core essential genome of Campylobacter jejuni and Campylobacter coli

Campylobacter species are the major cause of bacterial gastroenteritis. As there is no effective vaccine, combined with the rapid increase in antimicrobial resistant strains, there is a need to identify new targets for intervention. Essential genes are those that are necessary for growth and/or survival, making these attractive targets. In this study, comprehensive transposon mutant libraries were created in six C. jejuni strains, four C. coli strains and one C. lari and C. hyointestinalis strain, allowing for those genes that cannot tolerate a transposon insertion being called as essential. Comparison of essential gene lists using core genome analysis can highlight those genes which are common across multiple strains and/or species. Comparison of C. jejuni and C. coli, the two species that cause the most disease, identified 316 essential genes. Genes of interest highlighted members of the purine pathway being essential for C. jejuni whilst also finding that a functional potassium uptake system is essential. Protein-protein interaction networks using these essential gene lists also highlighted proteins in the purine pathway being major 'hub' proteins which have a large number of interactors across the network. When adding in two more species (C. lari and C. hyointestinalis) the essential gene list reduces to 261. Within these 261 essential genes, there are many genes that have been found to be essential in other bacteria. These include htrB and PEB4, which have previously been found as core virulence genes across Campylobacter species in other studies. There were 21 genes which have no known function with eight of these being associated with the membrane. These surface-associated essential genes may provide attractive targets. The essential gene lists presented will help to prioritise targets for the development of novel therapeutic and preventative interventions.

Prevalence and concentration of Campylobacter in faeces of dairy cows: A systematic review and meta-analysis

The consumption of raw milk from dairy cows has caused multiple food-borne outbreaks of campylobacteriosis in the European Union (EU) since 2011. Cross-contamination of raw milk through faeces is an important vehicle for transmission of Campylobacter to consumers. This systematic review and meta-analysis, aimed to summarize data on the prevalence and concentration of Campylobacter in faeces of dairy cows. Suitable scientific articles published up to July 2021 were identified through a systematic literature search and subjected to screening and quality assessment. Fifty-three out of 1338 identified studies were eligible for data extraction and 44 were further eligible for meta-analysis. The pooled prevalence was calculated in two different meta-analytic models: a simple model based on one average prevalence estimate per study and a multilevel meta-analytic model that included all prevalence outcomes reported in each study (including different subgroups of e.g. health status and age of dairy cows). The results of the two models were significantly different with a pooled prevalence estimate of 29%, 95% CI [23-36%] and 51%, 95% CI [44-57%], respectively. The effect of sub-groups on prevalence were analyzed with a multilevel mixed-effect model which showed a significant effect of the faecal collection methods and Campylobacter species on the prevalence. A meta-analysis on concentration data could not be performed due to the limited availability of data. This systematic review highlights important data gaps and limitations in current studies and variation of prevalence outcomes between available studies. The included studies used a variety of methods for sampling, data collection and analysis of Campylobacter that added uncertainty to the pooled prevalence estimates. Nevertheless, the performed meta-analysis improved our understanding of Campylobacter prevalence in faeces of dairy cows and is considered a valuable basis for the further development of quantitative microbiological risk assessment models for Campylobacter in (raw) milk and food products thereof.

Unravelling the reservoirs for colonisation of infants with Campylobacter spp. in rural Ethiopia: protocol for a longitudinal study during a global pandemic and political tensions

INTRODUCTION

Undernutrition is an underlying cause of mortality in children under five (CU5) years of age. Animal-source foods have been shown to decrease malnutrition in CU5. Livestock are important reservoirs for Campylobacter bacteria, which are recognised as risk factors for child malnutrition. Increasing livestock production may be beneficial for improving nutrition of children but these benefits may be negated by increased exposure to Campylobacter and research is needed to evaluate the complex pathways of Campylobacter exposure and infection applicable to low-income and middle-income countries. We aim to identify reservoirs of infection with Campylobacter spp. of infants in rural Eastern Ethiopia and evaluate interactions with child health (environmental enteric dysfunction and stunting) in the context of their sociodemographic environment.

METHODS AND ANALYSIS

This longitudinal study involves 115 infants who are followed from birth to 12 months of age and are selected randomly from 10 kebeles of Haramaya woreda, East Hararghe zone, Oromia region, Ethiopia. Questionnaire-based information is obtained on demographics, livelihoods, wealth, health, nutrition and women empowerment; animal ownership/management and diseases; and water, sanitation and hygiene. Faecal samples are collected from infants, mothers, siblings and livestock, drinking water and soil. These samples are analysed by a range of phenotypic and genotypic microbiological methods to characterise the genetic structure of the Campylobacter population in each of these reservoirs, which will support inference about the main sources of exposure for infants.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the University of Florida Internal Review Board (IRB201903141), the Haramaya University Institutional Health Research Ethics Committee (COHMS/1010/3796/20) and the Ethiopia National Research Ethics Review Committee (SM/14.1/1059/20). Written informed consent is obtained from all participating households. Research findings will be disseminated to stakeholders through conferences and peer-reviewed journals and through the Feed the Future Innovation Lab for Livestock Systems.

Rodent-Related Zoonotic Pathogens at the Human-Animal-Environment Interface in Qatar: A Systematic Review and Meta-Analysis

Rodents are one of the most diversified terrestrial mammals, and they perform several beneficial activities in nature. These animals are also important as carriers of many pathogens with public health importance. The current systematic review was conducted to formulate a true depiction of rodent-related zoonoses in Qatar. Following systematic searches on PubMed, Scopus, Science Direct, and Web of Science and a screening process, a total of 94 published articles were selected and studied. The studied articles reported 23 rodent-related zoonotic pathogens that include nine bacterial, eleven parasitic, and three viral pathogens, from which the frequently reported pathogens were Mycobacterium tuberculosis (32 reports), Escherichia coli (23), and Salmonella spp. (16). The possible pathway of entry of the rodent-borne pathogens can be the land port, seaports, and airport of Qatar through carrier humans and animals, contaminated food, and agricultural products. The pathogens can be conserved internally by rodents, pets, and livestock; by agricultural production systems; and by food marketing chains. The overall estimated pooled prevalence of the pathogens among the human population was 4.27% (95%CI: 4.03–4.51%; p < 0.001) with significant heterogeneity (I² = 99.50%). The top three highest prevalent pathogens were M.tuberculosis (30.90%; 22.75–39.04%; p < 0.001; I² = 99.70%) followed by Toxoplasma gondii (21.93%; 6.23–37.61%; p < 0.001; I² = 99.30%) and hepatitis E virus (18.29%; 11.72–24.86%; p < 0.001; I² = 96.70%). However, there is a knowledge gap about the listed pathogens regarding the occurrence, transmission pathways, and rodent role in transmission dynamics at the human–animal–environment interface in Qatar. Further studies are required to explore the role of rodents in spreading zoonotic pathogens through the One Health framework, consisting of zoologists, ecologists, microbiologists, entomologists, veterinarians, and public health experts in this country.

Campylobacter Colonization, Environmental Enteric Dysfunction, Stunting, and Associated Risk Factors Among Young Children in Rural Ethiopia: A Cross-Sectional Study From the Campylobacter Genomics and Environmental Enteric Dysfunction (CAGED) Project

Livestock farming provides a possible mechanism by which smallholder farmers can meet their household need for animal source foods (ASF), which may reduce the risk of stunting. However, direct/indirect contacts with domestic animals may increase colonization by Campylobacter spp., which has been associated with Environmental Enteric Dysfunction (EED) and stunting. A cross-sectional study involving 102 randomly selected children between 12 and 16 months of age was conducted in rural eastern Ethiopia to establish prevalence rates of Campylobacter colonization, EED, and stunting, and evaluate potential risk factors. Data were collected between September and December 2018. The prevalence of EED and stunting was 50% (95% CI: 40-60%) and 41% (95% CI: 32-51%), respectively. Among enrolled children, 56% had consumed some ASF in the previous 24 h; 47% had diarrhea and 50% had fever in the past 15 days. 54, 63, 71 or 43% of households owned at least one chicken, cow/bull, goat, or sheep; 54 (53%) households kept chickens indoors overnight and only half of these confined the animals. Sanitation was poor, with high levels of unimproved latrines and open defecation. Most households had access to an improved source of drinking water. The prevalence of Campylobacter colonization was 50% (95% CI: 41-60%) by PCR. In addition to the thermotolerant species Campylobacter jejuni, Campylobacter coli and Campylobacter upsaliensis, non-thermotolerant species related to Campylobacter hyointestinalis and Campylobacter fetus were frequently detected by Meta-total RNA sequencing (MeTRS). Current breastfeeding and ASF consumption increased the odds of Campylobacter detection by PCR, while improved drinking water supply decreased the odds of EED. No risk factors were significantly associated with stunting. Further studies are necessary to better understand reservoirs and transmission pathways of Campylobacter spp. and their potential impact on child health.

A One Health approach to prevention, treatment, and control of campylobacteriosis

PURPOSE OF REVIEW

To review recent findings regarding the control and treatment of campylobacteriosis.

RECENT FINDINGS

The application of improved diagnostics has led to an upward shift in the attributable burden of Campylobacter infections, in both the United States and Europe as well as in resource-poor settings. Increased focus has brought a fundamental feature of campylobacteriosis -- the ability to cause relapsing disease back into focus, and expanding data on antimicrobial resistance has lead from a switch in first-line therapy for severe diarrhea from quinolones to azithromycin in most contexts, even as evidence of expanding macrolide resistance emerges.

SUMMARY

Campylobacter spp. infection is a common infection worldwide. Antibiotic-resistant Campylobacter spp. has become an emerging threat with the increase in industrial poultry production, as well as the broad use of antibiotics in both animals and humans.

Detection of Campylobacter species in different types of samples from dairy farms

BACKGROUND

Livestock, domestic pets and wildlife can be intestinal carriers of thermotolerant Campylobacter species. These reservoirs can in turn contaminate the environment and food products, thus creating pathways to campylobacteriosis in human beings. The purposes of this study were to investigate sampling strategies applied for surveillance of Campylobacter on dairy cattle farms and to identify the presence and species of Campylobacter in different age groups.

METHODS

Boot sock and faecal samples were collected from five dairy herds from three age groups-cows, heifers and calves younger than 12 months-and from milk filters.

RESULTS

Campylobacter species were isolated in 152 of 250 samples, of which 93 isolates were identified as C jejuni, 51 as C hyointestinalis, two as C lari and one as C coli, whereas five isolates could not be identified to species level. Campylobacter species were isolated from 86 of 110 faecal samples, 60 of 97 sock samples and six of 43 milk filter samples.

CONCLUSION

Faecal samples were the optimal sample type for detection of Campylobacter on dairy farms. However, taking multiple types of samples could be recommended in order to optimise the recovery rate and variety of Campylobacter species detected when investigating the presence of Campylobacter on dairy farms.

Pathogenomics of Emerging Campylobacter Species

Campylobacter is among the four main causes of gastroenteritis worldwide and has increased in both developed and developing countries over the last 10 years. The vast majority of reported Campylobacter infections are caused by Campylobacter jejuni and, to a lesser extent, C. coli; however, the increasing recognition of other emerging Campylobacter pathogens is urgently demanding a better understanding of how these underestimated species cause disease, transmit, and evolve. In parallel to the enhanced clinical awareness of campylobacteriosis due to improved diagnostic protocols, the application of high-throughput sequencing has increased the number of whole-genome sequences available to dozens of strains of many emerging campylobacters. This has allowed for comprehensive comparative pathogenomic analyses for several species, such as C. fetus and C. concisus These studies have started to reveal the evolutionary forces shaping their genomes and have brought to light many genomic features related to pathogenicity in these neglected species, promoting the development of new tools and approaches relevant for clinical microbiology. Despite the need for additional characterization of genomic diversity in emerging campylobacters, the increasing body of literature describing pathogenomic studies on these species deserves to be discussed from an integrative perspective. This review compiles the current knowledge and highlights future work toward deepening our understanding about genome dynamics and the mechanisms governing the evolution of pathogenicity in emerging Campylobacter species, which is urgently needed to develop strategies to prevent or control the spread of these pathogens.

Effects of clay mineral supplementation on particle-associated and epimural microbiota, and gene expression in the rumen of cows fed high-concentrate diet

The increased concentrate amounts in cow diets may initiate changes in both particle-associated (PaM) and epimural microbiota (EpM) with the potential for promoting the establishment of pathogens. Clay minerals have shown promising potentials in binding harmful microorganisms and metabolites due to their high adsorption capacity. This study evaluated the effects of a clay-mineral based product (CM) on PaM, EpM, fermentation parameters, and epithelial gene expression in cows fed a high-concentrate diet. Eight rumen-cannulated non-lactating Holstein cows received a concentrate mix supplemented with CM or not (CON) in a change-over design with an initial 100% roughage diet phase (RD, 1 week), followed by intermittent 65%-high-concentrate-diet phases (HC1, HC2; 1 and 2 week duration, respectively), interrupted by 1 week roughage only. Rumen samples for short-chain fatty acids, ammonia, and lactate quantification, as well as PaM, and epithelial biopsies for EpM examination and epithelial gene expression were collected via the cannula once during each feeding phase. Phylogenetic distance analysis of Illumina MiSeq sequencing of the 16S rRNA gene region V345 showed a clear clustering of RD microbiota compared to HC in PaM, showing the impact of the high-concentrate diet on the bacterial community. In the EpM this effect was less pronounced, due to higher variability in RD. In the PaM, a decrease (P < 0.01) of community diversity occurred with the onset of HC feeding, while in the EpM there was an increase in diversity (P < 0.05). In the PaM, CM increased the relative abundance of genus Butyrivibrio (P < 0.01), a commensal bacterium of the rumen, which was, with 6.4%, the second most abundant genus. There, the CM supplementation decreased the genera Lactobacillus, Fusobacterium, and Treponema (P = 0.05), which are potentially either lactate producing or opportunistic pathogens. In the EpM, CM decreased the relative abundance of Succiniclasticum genus (P < 0.01), a possible endotoxin producer, and increased bacteria that are associated with a normobiotic rumen, such as Campylobacter (P = 0.06). Barrier function genes were upregulated in HC2 and nutrient transport genes downregulated in HC1 (P < 0.05); however, there was little effect on pro-inflammatory genes at the epithelium. The CM showed a significant decreasing effect on the cellular metabolism genes HMGCS1 (P = 0.04). Our results suggest that CM supplementation can increase the relative abundance of commensal microbiota and decrease bacteria that could negatively impact the rumen milieu and health during high-concentrate feeding.

Draft Genome Sequences of Nine Campylobacter hyointestinalis subsp. lawsonii Strains

With increasing reports of Campylobacter hyointestinalis species associated with human diseases, more genome sequences are required to understand the virulence mechanisms of this emerging pathogen. Here, we describe the genome sequences of nine C. hyointestinalis subsp. lawsonii strains.

With increasing reports of Campylobacter hyointestinalis species associated with human diseases, more genome sequences are required to understand the virulence mechanisms of this emerging pathogen. Here, we describe the genome sequences of nine C. hyointestinalis subsp. lawsonii strains.

The Clinical Importance of Campylobacter concisus and Other Human Hosted Campylobacter Species

Historically, Campylobacteriosis has been considered to be zoonotic; the Campylobacter species that cause human acute intestinal disease such as Campylobacter jejuni and Campylobacter coli originate from animals. Over the past decade, studies on human hosted Campylobacter species strongly suggest that Campylobacter concisus plays a role in the development of inflammatory bowel disease (IBD). C. concisus primarily colonizes the human oral cavity and some strains can be translocated to the intestinal tract. Genome analysis of C. concisus strains isolated from saliva samples has identified a bacterial marker that is associated with active Crohn's disease (one major form of IBD). In addition to C. concisus, humans are also colonized by a number of other Campylobacter species, most of which are in the oral cavity. Here we review the most recent advancements on C. concisus and other human hosted Campylobacter species including their clinical relevance, transmission, virulence factors, disease associated genes, interactions with the human immune system and pathogenic mechanisms.

Towards understanding clinical campylobacter infection and its transmission: time for a different approach?

Campylobacter spp. are among the most commonly diagnosed causes of human infection. Methods for detection of the 29 campylobacter species have mainly focused on cultivation of the thermophilic species. More than 99% of clinical campylobacter isolates notified in the UK in the recent past have been from faecal samples and associated with gastroenteritis. Campylobacter enteritis notifications in temperate zones show a seasonal increase during the summer months with a sharp decrease in the winter months, a pattern which remains incompletely understood. The striking seasonality in the expression of many human genes, some concerned with inflammation and immunity, suggests a need for further study of the host regarding the temporal distribution of many human infections, including campylobacteriosis. A tendency for campylobacter to enter a non-cultivable state under adverse conditions effects a reduction in the number of isolations. A Polymerase Chain Reaction (PCR)-based screening approach for the presence of the Campylobacter genus and followed by speciation has provided some insight into the limitations of cultivation for campylobacter, also allowing the discovery of new species. The increased sensitivity of the PCR-based approach over culture-based methods may make it difficult for the laboratory to differentiate asymptomatic campylobacter carriage from clinical campylobacter infection in non-sterile body sites. Campylobacter infection depends on a combination of host factors, and on acquisition of a suitably virulent strain with a tropism for human epithelium. The possibility of persistence of campylobacter in a viable but non-culturable latent form in the human body may also require further investigation. The scope of this review includes a discussion of current methods for diagnosing acute campylobacter infection and for detecting campylobacter in water and foodstuffs. The review also questions the prevailing view that poultry is the most common source of campylobacteriosis.

A PCR-RFLP assay to detect and type cytolethal distending toxin (cdt) genes in Campylobacter hyointestinalis

Campylobacter hyointestinalis is considered as an emerging zoonotic pathogen. We have recently identified two types of cytolethal distending toxin (cdt) gene in C. hyointestinalis and designated them as Chcdt-I and Chcdt-II. In this study, we developed a PCR-restriction fragment length polymorphism (RFLP) assay that can differentiate Chcdt-I from Chcdt-II. When the PCR-RFLP assay was applied to 17 other Campylobacter strains and 25 non-Campylobacter strains, PCR products were not obtained irrespective of their cdt gene-possession, indicating that the specificity of the PCR-RFLP assay was 100%. In contrast, when the PCR-RFLP assay was applied to 35 C. hyointestinalis strains including 23 analyzed in the previous study and 12 newly isolated from pigs and bovines, all of them showed the presence of cdt genes. Furthermore, a restriction digest by EcoT14-I revealed that 29 strains contained both Chcdt-I and Chcdt-II and 6 strains contained only Chcdt-II, showing 100% sensitivity. Unexpectedly, however, PCR products obtained from 7 C. hyointestinalis strains were not completely digested by EcoT14-I. Nucleotide sequence analysis revealed that the undigested PCR product was homologous to cdtB but not to Chcdt-IB or Chcdt-IIB, indicating the presence of another cdt gene-variant. Then, we further digested the PCR products with DdeI in addition to EcoT14-I, showing that all three cdt genes, including a possible new Chcdt variant, could be clearly differentiated. Thus, the PCR-RFLP assay developed in this study is a valuable tool for evaluating the Chcdt gene-profile of bacteria.

The Cytolethal Distending Toxin Contributes to Microbial Virulence and Disease Pathogenesis by Acting As a Tri-Perditious Toxin

This review summarizes the current status and recent advances in our understanding of the role that the cytolethal distending toxin (Cdt) plays as a virulence factor in promoting disease by toxin-producing pathogens. A major focus of this review is on the relationship between structure and function of the individual subunits that comprise the AB₂ Cdt holotoxin. In particular, we concentrate on the molecular mechanisms that characterize this toxin and which account for the ability of Cdt to intoxicate multiple cell types by utilizing a ubiquitous binding partner on the cell membrane. Furthermore, we propose a paradigm shift for the molecular mode of action by which the active Cdt subunit, CdtB, is able to block a key signaling cascade and thereby lead to outcomes based upon programming and the role of the phosphatidylinositol 3-kinase (PI-3K) in a variety of cells. Based upon the collective Cdt literature, we now propose that Cdt is a unique and potent virulence factor capable of acting as a tri-perditious toxin that impairs host defenses by: (1) disrupting epithelial barriers; (2) suppressing acquired immunity; (3) promoting pro-inflammatory responses. Thus, Cdt plays a key role in facilitating the early stages of infection and the later stages of disease progression by contributing to persistence and impairing host elimination.

Campylobacter hyointestinalis Isolated from Pigs Produces Multiple Variants of Biologically Active Cytolethal Distending Toxin

Campylobacter hyointestinalis isolated from swine with proliferative enteritis often is considered to be pathogenic. While the precise virulence mechanisms of this species remain unclear, we have recently identified a cytolethal distending toxin (cdt) gene cluster in C. hyointestinalis isolated from a patient with diarrhea (W. Samosornsuk et al., J Med Microbiol, 27 July 2015, http://dx.doi.org/10.1099/jmm.0.000145). However, the sequences of the cdt genes in C. hyointestinalis were found to be significantly different and the gene products are immunologically distinct from those of other Campylobacter species. In this study, we demonstrate the presence of a second variant of the cdt gene cluster in C. hyointestinalis, designated cdt-II, while the former is named cdt-I. Sequencing of the cdt-II gene cluster and deduced amino acid sequences revealed that homologies between the subunits CdtA, CdtB, and CdtC of ChCDT-I and ChCDT-II are 25.0, 56.0, and 24.8%, respectively. Furthermore, the CdtB subunit of ChCDT-II was found to be immunologically unrelated to that of ChCDT-I by Ouchterlony double gel diffusion test. Recombinant ChCDT-II also induced cell distention and death of HeLa cells by blocking the cell cycle at G2/M phase. Interestingly, the cdt-II genes were detected in all 23 animal isolates and in 1 human isolate of C. hyointestinalis, and 21 of these strains carried both cdt-I and cdt-II gene clusters. Altogether, our results indicate that ChCDT-II is an important virulence factor of C. hyointestinalis in animals.

Update on the burden of Campylobacter in developing countries

PURPOSE OF REVIEW

Recent work has added to the understanding of the burden of Campylobacter jejuni, C. coli, and non-jejuni/coli Campylobacter strains in children living in the developing world.

RECENT FINDINGS

New diagnostic modalities and carefully designed field studies are demonstrating that the burden of Campylobacter diarrhea in children in the developing world has been greatly underestimated. Furthermore, there is emerging recognition of an association between Campylobacter infection and malnutrition. Important progress has been made toward a Campylobacter jejuni vaccine. Finally, evidence of antibiotic resistance continues to be an important issue that is accentuated by the realization that the burden of disease is greater than previously recognized.

SUMMARY

Additional research is needed to refine our understanding of the epidemiology of Campylobacter infections in developing countries, in particular to improve estimates of the burden of Campylobacter diarrhea in endemic settings, to determine the impact of recurrent Campylobacter infections on child development, and to describe the prevalence and clinical significance of non-jejuni/coli Campylobacter infections. Progressive antibiotic resistance of isolates argues for augmented and expanded control measures of antibiotics in livestock. Continued work in vaccine development is warranted as is the extension of data available on the serotypes related to burden in different areas of the world and the relationship of serotypes to disease severity.

Antibiotic susceptibility pattern and genotyping of campylobacter species isolated from children suffering from gastroenteritis

PURPOSE

To study the prevalence and the antimicrobial resistance of campylobacter species isolated from children suffering from gastroenteritis .

MATERIALS AND METHODS

A total of 125 stool samples were collected from children with gastroenteritis. The identification of isolates was performed with conventional methods as well as with molecular methods based on 16SrRNA species-specific gene amplification by PCR and product analysis. Resistance pattern of the isolated strains was determined using agar dilution method.

RESULTS

Conventional methods including sodium hippurate hydrolysis revealed that 12 (9.6%) samples were positive for Campylobacter species. Ten out of 12 Campylobacter spp. were identified as Campylobacter jejuni and 2 as Campylobacter coli but PCR assay revealed that five samples only were positive for Campylobacter and all were C. jejuni. Antimicrobial susceptibility to 10 antimicrobials was performed and all isolates (five isolates of C. jejuni) were susceptible to chloramphenicol, gentamicin and amikacin but all were resistant to ceftriaxone.

CONCLUSION

PCR assay method allows reliable detection of C. jejuni. C. jejuni was the most prevalent Campylobacter species. Gentamicin, amikacin and chloramphenicol were the most effective antibiotic.

Prevalence and diversity of Campylobacter species in Saskatchewan retail ground beef

The primary objective of this study was to investigate the prevalence of Campylobacter spp. DNA by PCR in retail ground beef sold in Saskatchewan, Canada, and to identify the presence of individual Campylobacter species (C. coli, C. curvus, C. fetus, C. hyointestinalis, C. jejuni, C. rectus, and C. upsaliensis) using real-time quantitative PCR (qPCR). Secondary objectives were to assess potential differences in the prevalence of Campylobacter between ground beef offered for sale during cold and warm seasons as well as that offered for sale fresh and frozen, to investigate any association between the presence of Campylobacter spp. DNA and E. coli and/or aerobic bacterial counts, and finally to compare the prevalence of Campylobacter spp. DNA in ground beef originating from different production and retail environments. Out of the 309 total samples included in the study, 50 (16.2%) samples tested positive for Campylobacter spp. DNA, while 49 (15.9%) samples were determined positive for up to five individual species. Collectively, these assays determined that 14 (4.5%) samples were positive for C. coli, 11 (3.6%) for C. curvus, 6 (1.9%) for C. fetus, 24 (7.8%) for C. hyointestinalis, 12 (3.9%) for C. jejuni, 6 (1.9%) for C. rectus, and 9 (2.9%) for C. upsaliensis. There were 27 (8.7%) samples that were positive at the genus level that did not test positive for any of the seven Campylobacter species investigated (suggesting an alternate Campylobacter species). Also, 26 (8.4%) samples generated positive results by one of the species-specific qPCR assays, but returned no product in the conventional genus-level assay (suggesting a higher sensitivity for the species-specific qPCR assays). There was no significant association between the presence of Campylobacter spp. in Saskatchewan retail ground beef and any of the investigated risk factors.

Occurrence, diversity, and host association of intestinal Campylobacter, Arcobacter, and Helicobacter in reptiles

Campylobacter, Arcobacter, and Helicobacter species have been isolated from many vertebrate hosts, including birds, mammals, and reptiles. Multiple studies have focused on the prevalence of these Epsilonproteobacteria genera in avian and mammalian species. However, little focus has been given to the presence within reptiles, and their potential zoonotic and pathogenic roles. In this study, occurrence, diversity, and host association of intestinal Epsilonproteobacteria were determined for a large variety of reptiles. From 2011 to 2013, 444 cloacal swabs and fecal samples originating from 417 predominantly captive-held reptiles were screened for Epsilonproteobacteria. Campylobacter, Arcobacter, and Helicobacter genus specific PCRs were performed directly on all samples. All samples were also cultured on selective media and screened for the presence of Epsilonproteobacteria. Using a tiered approach of AFLP, atpA, and 16S rRNA sequencing, 432 Epsilonproteobacteria isolates were characterized at the species level. Based on PCR, Campylobacter, Arcobacter, and Helicobacter were detected in 69.3% of the reptiles; 82.5% of the chelonians, 63.8% of the lizards, and 58.0% of the snakes were positive for one or more of these genera. Epsilonproteobacteria were isolated from 22.1% of the reptiles and were isolated most frequently from chelonians (37.0%), followed by lizards (19.6%) and snakes (3.0%). The most commonly isolated taxa were Arcobacter butzleri, Arcobacter skirrowii, reptile-associated Campylobacter fetus subsp. testudinum, and a putative novel Campylobacter taxon. Furthermore, a clade of seven related putative novel Helicobacter taxa was isolated from lizards and chelonians. This study shows that reptiles carry various intestinal Epsilonproteobacteria taxa, including several putative novel taxa.

Detection of Campylobacter species and Arcobacter butzleri in stool samples by use of real-time multiplex PCR

The presence of Campylobacter (or Campylobacter-like) species in stools from patients suspected of infectious gastroenteritis (n = 493) was investigated using real-time PCR for detection of Arcobacter butzleri (hsp60 gene), Campylobacter coli (ceuE gene), Campylobacter jejuni (mapA), five acknowledged pathogenic Campylobacter spp. (C16S_Lund assay), and the Campylobacter genus (C16S_LvI assay). In total, 71.4% of the samples were positive for Campylobacter DNA (n = 352) by a Campylobacter genus-specific (C16S_LvI) assay. A total of 23 samples (4.7%) were positive in the C16S_Lund assay, used for detection of C. jejuni, C. coli, C. lari, C. upsaliensis, and C. hyointestinalis. Subsequent identification of these samples yielded detection frequencies (DF) of 4.1% (C. jejuni), 0.4% (C. coli), and 0.4% (C. upsaliensis). The DF of A. butzleri was 0.4%. Interestingly, sequencing of a subgroup (n = 46) of C16S_LvI PCR-positive samples resulted in a considerable number of Campylobacter concisus-positive samples (n = 20). PCR-positive findings with the C16S_Lund and C. jejuni/C. coli-specific assays were associated with more serious clinical symptoms (diarrhea and blood). Threshold cycle (C(T)) values of C. jejuni/C. coli PCR-positive samples were comparable to those of the C16S_Lund PCR (P = 0.21). C(T) values for both assays were significantly lower than those of the C16S_LvI assay (P < 0.001 and P < 0.00001, respectively). In conclusion, this study demonstrated that in combination, the C. jejuni/C coli-specific assays and the C16S_Lund assay are both useful for routine screening purposes. Furthermore, the DF of the emerging pathogen C. concisus was at least similar to the DF of C. jejuni.

Multilocus sequence typing methods for the emerging Campylobacter Species C. hyointestinalis, C. lanienae, C. sputorum, C. concisus, and C. curvus

Multilocus sequence typing (MLST) systems have been reported previously for multiple food- and food animal-associated Campylobacter species (e.g., C. jejuni, C. coli, C. lari, and C. fetus) to both differentiate strains and identify clonal lineages. These MLST methods focused primarily on campylobacters of human clinical (e.g., C. jejuni) or veterinary (e.g., C. fetus) relevance. However, other, emerging, Campylobacter species have been isolated increasingly from environmental, food animal, or human clinical samples. We describe herein four MLST methods for five emerging Campylobacter species: C. hyointestinalis, C. lanienae, C. sputorum, C. concisus, and C. curvus. The concisus/curvus method uses the loci aspA, atpA, glnA, gltA, glyA, ilvD, and pgm, whereas the other methods use the seven loci defined for C. jejuni (i.e., aspA, atpA, glnA, gltA, glyA, pgm, and tkt). Multiple food animal and human clinical C. hyointestinalis (n = 48), C. lanienae (n = 34), and C. sputorum (n = 24) isolates were typed, along with 86 human clinical C. concisus and C. curvus isolates. A large number of sequence types were identified using all four MLST methods. Additionally, these methods speciated unequivocally isolates that had been typed ambiguously using other molecular-based speciation methods, such as 16S rDNA sequencing. Finally, the design of degenerate primer pairs for some methods permitted the typing of related species; for example, the C. hyointestinalis primer pairs could be used to type C. fetus strains. Therefore, these novel Campylobacter MLST methods will prove useful in differentiating strains of multiple, emerging Campylobacter species.

Cytolethal distending toxin: a conserved bacterial genotoxin that blocks cell cycle progression, leading to apoptosis of a broad range of mammalian cell lineages

Cytolethal distending toxin (CDT) is a heterotrimeric AB-type genotoxin produced by several clinically important Gram-negative mucocutaneous bacterial pathogens. Irrespective of the bacterial species of origin, CDT causes characteristic and irreversible cell cycle arrest and apoptosis in a broad range of cultured mammalian cell lineages. The active subunit CdtB has structural homology with the phosphodiesterase family of enzymes including mammalian DNase I, and alone is necessary and sufficient to account for cellular toxicity. Indeed, mammalian cells treated with CDT initiate a DNA damage response similar to that elicited by ionizing radiation-induced DNA double strand breaks resulting in cell cycle arrest and apoptosis. The mechanism of CDT-induced apoptosis remains incompletely understood, but appears to involve both p53-dependent and -independent pathways. While epithelial, endothelial and fibroblast cell lines respond to CDT by undergoing arrest of cell cycle progression resulting in nuclear and cytoplasmic distension that precedes apoptotic cell death, cells of haematopoietic origin display rapid apoptosis following a brief period of cell cycle arrest. In this review, the ecology of pathogens producing CDT, the molecular biology of bacterial CDT and the molecular mechanisms of CDT-induced cytotoxicity are critically appraised. Understanding the contribution of a broadly conserved bacterial genotoxin that blocks progression of the mammalian cell cycle, ultimately causing cell death, should assist with elucidating disease mechanisms for these important pathogens.

The internal transcribed spacer region, a new tool for use in species differentiation and delineation of systematic relationships within the Campylobacter genus

The Campylobacter genus consists of a number of important human and animal pathogens. Although the 16S rRNA gene has been used extensively for detection and identification of Campylobacter species, there is currently limited information on the 23S rRNA gene and the internal transcribed spacer (ITS) region that lies between the 16S and 23S rRNA genes. We examined the potential of the 23S rRNA gene and the ITS region to be used in species differentiation and delineation of systematic relationships for 30 taxa within the Campylobacter genus. The ITS region produced the highest mean pairwise percentage difference (35.94%) compared to the 16S (5.34%) and 23S (7.29%) rRNA genes. The discriminatory power for each region was further validated using Simpson's index of diversity (D value). The D values were 0.968, 0.995, and 0.766 for the ITS region and the 23S and 16S rRNA genes, respectively. A closer examination of the ITS region revealed that Campylobacter concisus, Campylobacter showae, and Campylobacter fetus subsp. fetus harbored tRNA configurations not previously reported for other members of the Campylobacter genus. We also observed the presence of strain-dependent intervening sequences in the 23S rRNA genes. Neighbor-joining trees using the ITS region revealed that Campylobacter jejuni and Campylobacter coli strains clustered in subgroups, which was not observed in trees derived from the 16S or 23S rRNA gene. Of the three regions examined, the ITS region is by far the most cost-effective region for the differentiation and delineation of systematic relationships within the Campylobacter genus.

Campylobacter proteomics: guidelines, challenges and future perspectives

Campylobacter species are a major cause of disease in mammalian systems. The most common human etiological agent within this genus is Campylobacter jejuni - the leading cause of bacterial gastroenteritis in the developed world. While this organism has been extensively studied at the cellular level, and the genome sequences of several strains have now been elucidated, little is known regarding the role of individual proteins in virulence processes, such as adhesion, colonization and toxicity towards host cells. Proteomics encompasses the global analysis of proteins at the organism level. The technologies included under this term have now started to be utilized for understanding how Campylobacter species respond to changes in the environment, with an emphasis on the human host, as well as to map subcellular locations of proteins, in particular those that are surface-associated. C. jejuni is also of great significance as, unlike most other bacteria, it is able to post-translationally modify its proteins. The analysis of such proteins represents a major challenge in understanding this organism at the proteomic and cellular levels. This review will examine the state-of-the-art in Campylobacter proteomics, as well as provide insights into strategies that need to be undertaken to provide a comprehensive understanding of this organism at the molecular and functional level.

Influence of pH of TSI medium on the detection of hydrogen sulfide production by Campylobacter hyointestinalis

AIMS

To examine the influence of pH of triple sugar iron (TSI) agar medium on the detection of hydrogen sulfide (H(2)S) production in Campylobacter hyointestinalis ssp. hyointestinalis (CHH).

METHODS AND RESULTS

TSI medium was adjusted by the addition in HCl or NaOH to cover a pH 6.0-9.0. One loopful of bacterial growth of CHH strain ATCC 35217 was inoculated into each different pH medium, and incubated at 37 degrees C under micro-aerobic conditions. The H(2)S production was not detectable even after incubation for 72 h in acidic medium pH; however, TSI with alkaline pH (8.0-9.0) allowed detection as early as 3 h of incubation. A total of 20 CHH strains from various animal sources were examined for the detection of H(2)S production in TSI medium with pH 9.0. The H(2)S was detected in all the strains examined within 12 h, and the judgment was unambiguous.

CONCLUSION

The results showed that the detection of H(2)S production by CHH was influenced by medium pH, and TSI with alkaline condition is highly sensitive.

SIGNIFICANCE AND IMPACT OF THE STUDY

The findings of the present study suggest that TSI medium with alkaline pH contributes to fast detection and led to unambiguous judgment of H(2)S production by CHH.

Campylobacter spp., Enterococcus spp., Escherichia coli, Salmonella spp., Yersinia spp., and Cryptosporidium oocysts in semi-domesticated reindeer (Rangifer tarandus tarandus) in Northern Finland and Norway

The specific aim of this study was to assess the faecal shedding of zoonotic enteropathogens by semi-domesticated reindeer (Rangifer tarandus tarandus) to deduce the potential risk to human health through modern reindeer herding. In total, 2,243 faecal samples of reindeer from northern regions of Finland and Norway were examined for potentially enteropathogenic bacteria (Campylobacter species, Enterococcus species, Escherichia coli, Salmonella species and Yersinia species) and parasites (Cryptosporidium species) in accordance with standard procedures. Escherichia coli were isolated in 94.7%, Enterococcus species in 92.9%, Yersinia species in 4.8% of the samples and Campylobacter species in one sample only (0.04%). Analysis for virulence factors in E. coli and Yersinia species revealed no pathogenic strains. Neither Salmonella species nor Cryptosporidium oocysts were detected. The public health risk due to reindeer husbandry concerning zoonotic diseases included in this study has to be considered as very low at present but a putative epidemiological threat may arise when herding conditions are changed with respect to intensification and crowding.

Effects of subtherapeutic administration of antimicrobial agents to beef cattle on the prevalence of antimicrobial resistance in Campylobacter jejuni and Campylobacter hyointestinalis

The influence of antimicrobial agents on the development of antimicrobial resistance (AMR) in Campylobacter isolates recovered from 300 beef cattle maintained in an experimental feedlot was monitored over a 315-day period (11 sample times). Groups of calves were assigned to one of the following antimicrobial treatments: chlortetracycline and sulfamethazine (CS), chlortetracycline alone (Ct), virginiamycin, monensin, tylosin phosphate, and no antimicrobial agent (i.e., control treatment). In total, 3,283 fecal samples were processed for campylobacters over the course of the experiment. Of the 2,052 bacterial isolates recovered, 92% were Campylobacter (1,518 were Campylobacter hyointestinalis and 380 were C. jejuni). None of the antimicrobial treatments decreased the isolation frequency of C. jejuni relative to the control treatment. In contrast, C. hyointestinalis was isolated less frequently from animals treated with CS and to a lesser extent from animals treated with Ct. The majority (> or =94%) of C. jejuni isolates were sensitive to ampicillin, erythromycin, and ciprofloxacin, but more isolates with resistance to tetracycline were recovered from animals fed Ct. All of the 1,500 isolates of C. hyointestinalis examined were sensitive to ciprofloxacin. In contrast, 11%, 10%, and 1% of these isolates were resistant to tetracycline, erythromycin, and ampicillin, respectively. The number of animals from which C. hyointestinalis isolates with resistance to erythromycin and tetracycline were recovered differed among the antimicrobial treatments. Only Ct administration increased the carriage rates of erythromycin-resistant isolates of C. hyointestinalis, and the inclusion of CS in the diet increased the number of animals from which tetracycline-resistant isolates were recovered. The majority of C. hyointestinalis isolates with resistance to tetracycline were obtained from cohorts within a single pen, and most of these isolates were recovered from cattle during feeding of a forage-based diet as opposed to a grain-based diet. The findings of this study show that the subtherapeutic administration of tetracycline, alone and in combination with sulfamethazine, to feedlot cattle can select for the carriage of resistant strains of Campylobacter species. Considering the widespread use of in-feed antimicrobial agents and the high frequency of beef cattle that shed campylobacters, the development of AMR should be monitored as part of an on-going surveillance program.

Description of Campylobacter curvus and C. curvus-like strains associated with sporadic episodes of bloody gastroenteritis and Brainerd's diarrhea

Campylobacter curvus is a rarely encountered Campylobacter species in human, animal, and environmental samples. During the course of two investigations, one involving a search for possible bacterial agents causing bloody gastroenteritis and a second concerning a small outbreak of Brainerd's diarrhea in northern California, 20 strains of C. curvus or C. curvus-like organisms were isolated by a microfiltration technique and prolonged incubation. The results suggest that C. curvus may be an underappreciated Campylobacter that may be involved in sporadic and outbreak cases of bloody or chronic diarrhea in humans.

Susceptibility of Campylobacter hyointestinalis subsp. hyointestinalis to antimicrobial agents and characterization of quinolone-resistant strains

OBJECTIVES

To study the susceptibility of Campylobacter hyointestinalis subsp. hyointestinalis to several antimicrobial agents and to investigate the mechanisms of nalidixic acid and ciprofloxacin resistance.

METHODS

The disc diffusion method was employed to study the susceptibility of 49 C. hyointestinalis subsp. hyointestinalis strains of reindeer and bovine origin to 12 different antimicrobial agents. In addition, the MICs of nalidixic acid and ciprofloxacin were determined. The nucleotide sequence of a 270 bp fragment of the gyrA gene was determined in ciprofloxacin-susceptible and -resistant strains. The effect of a multidrug efflux pump inhibitor Phe-Arg-beta-naphthylamide (PA beta N) on the MICs of ciprofloxacin and nalidixic acid was also studied.

RESULTS

The only decreased susceptibility for antimicrobial agents of this study was observed for sulphonamide compound and streptomycin (24% and 32% of the strains, respectively), and this phenomenon was observed exclusively in the bovine strains. In sequence studies, a Thr-86-->Ile change was found in strains with MICs of ciprofloxacin of > or = 64 mg/L, but this mutation was absent in strains with lower resistance levels. The use of PA beta N did not affect the MIC of ciprofloxacin but decreased the MIC of nalidixic acid 2-4-fold.

CONCLUSIONS

The Finnish C. hyointestinalis subsp. hyointestinalis strains are susceptible to a majority of the antimicrobials of veterinary importance. The mechanism of ciprofloxacin resistance at lower levels (< or = 32 mg/L) is not associated with a specific mutation in the quinolone resistance-determining region of the gyrA gene. Finally, there are distinct differences in the mechanisms of ciprofloxacin resistance compared with nalidixic acid resistance within the studied species.

Evaluation of the ProSpecT Microplate Assay for detection of Campylobacter: a routine laboratory perspective

OBJECTIVES

To evaluate the use of the new enzyme-linked immunosorbent assay, the ProSpecT Campylobacter Microplate Assay (Alexon-Trend, Minneapolis, MN, USA), which allows 2-h detection of both Campylobacter jejuni and Campylobacter coli antigen directly in stool specimens.

METHODS

Over 4 months, all stool samples preserved in Cary-Blair medium, or fresh specimens, from non-hospitalized children and HIV-infected patients (adults and children), submitted to our laboratory were evaluated with the ProSpecT Campylobacter Microplate Assay. Results were compared with those obtained by routine culture methods using both a specific medium and a filtration method for the recovery of Campylobacter spp.

RESULTS

Of the 1205 stool specimens cultured, 101 were found to be positive for either C. jejuni or C. coli, giving an overall recovery rate of 8.38%. Ninety samples were positive by both culture and ProSpecT Campylobacter Microplate Assay, and 11 were positive by culture only, giving a sensitivity of 89.1%. In addition, of 1104 samples negative by culture, 25 were initially positive by ProSpecT Campylobacter Microplate Assay. We found no cross-reaction with other bacterial enteropathogens isolated from stool specimens. These results thus confirm a high specificity (97.7%) for both C. jejuni and C. coli. The positive and negative predictive values found were 78.3% and 99%, respectively. There was no statistically significant difference in sensitivity and specificity if the stool was fresh or preserved with Cary-Blair medium.

CONCLUSION

These data suggest that the ProSpecT Campylobacter Microplate Assay is a rapid and easy-to-use test for the detection of both C. jejuni and C. coli in stool specimens. It could be used for patients for whom early antibiotic therapy is needed or for epidemiologic studies.

Detection of campylobacter species: a comparison of culture and polymerase chain reaction based methods

AIMS

To investigate the optimal method for the detection of campylobacters from stool samples by comparing selective culture with membrane filtration and the polymerase chain reaction (PCR).

METHODS

Three hundred and forty three stool samples were investigated by each of the three methods mentioned above. Selective culture was performed with charcoal cefoperazone desoxycholate agar plates. Membrane filtration was performed using cellulose triacetate membranes with 0.45 micro m pores placed on blood agar plates. Enteropathogenic campylobacters were detected using a PCR identification algorithm, consisting of screening PCRs and species identification using a PCR enzyme linked immunosorbent assay (PCR-ELISA), both based on the 16S rRNA gene.

RESULTS

Of the 343 samples tested, 23 were positive by one or more method. Of these, 17 were positive by selective culture, 12 by membrane filtration, and 20 by the PCR identification algorithm. A total of 18 of 23 positives were identified as C jejuni and/or C coli by the PCR identification algorithm, compared with 14 identified to the genus level by selective culture, and 10 by membrane filtration. Among the remaining five positive samples, one C hyointestinalis was detected only by the PCR identification algorithm; one C upsaliensis was detected only by the PCR identification algorithm; one Campylobacter sp was detected by membrane filtration and selective culture and later identified as C concisus; one Campylobacter sp was detected by membrane filtration alone and later identified as Arcobacter sp; and one Campylobacter sp detected only by selective culture was lost to study and therefore not speciated. There was no significant difference between detection by selective culture and the other two methods. However, detection by PCR was significantly better than by membrane filtration (0.05 > p > 0.02).

CONCLUSION

The PCR identification algorithm can detect and identify Campylobacter spp to the species level and the result is obtained on the same day. However, PCR is expensive, labour intensive, and does not provide an isolate for further identification or typing. Selective culture is as good as the PCR identification algorithm for the detection of the two most common species, C jejuni and C coli, and it is cheap and practical. However, it does miss the less common species, results take 48 hours, and identification is only to the genus level. Membrane filtration showed a low sensitivity compared with the other methods and is not appropriate for the diagnostic laboratory, although it was the only method to detect the Arcobacter sp. The optimum method for the detection of campylobacters from stool samples in the diagnostic laboratory remains selective culture.

Campylobacter hyointestinalis subsp. hyointestinalis, a common Campylobacter species in reindeer

AIMS

To study the prevalence of Campylobacter spp. in the faecal material of reindeer, and to identify the isolates by means of a polyphasic approach. In addition, to study the genetic diversity of Camp. hyointestinalis subsp. hyointestinalis reindeer isolates by pulsed-field gel electrophoresis (PFGE).

METHODS AND RESULTS

The material, collected during the slaughter period in autumn 1998, comprised 399 faecal contents from the reindeer (Rangifer tarandus), a semi-domesticated, meat-producing ruminant of northern Finland. These samples came from 16 herds in the areas of eight reindeer slaughterhouses. Samples were cultured by methods suitable for isolation of fastidious Campylobacter species. Of all samples, 6% (24/399) were Campylobacter-positive. Phenotypic characteristics, SDS-PAGE protein patterns, dot blot DNA-DNA hybridization, 23S rDNA restriction fragment polymorphism analysis and PFGE identified the isolates as Camp. hyointestinalis subsp. hyointestinalis.

CONCLUSIONS

Campylobacter hyointestinalis subsp. hyointestinalis was the only Campylobacter species isolated from reindeer in this study. The isolates showed high genomic diversity in PFGE with the restriction enzymes SmaI and KpnI.

SIGNIFICANCE AND IMPACT OF THE STUDY

PFGE analysis is a useful subtyping method for epidemiological studies. Contaminated reindeer meat can be a source for human infections.

Gastrointestinal infections

Advances in public health have reduced the risk of contracting certain enteric diseases, but many remain, and new pathogens have emerged and/or recently have been discovered. The pathogenic agents are varied and consist of a variety of bacteria and select viruses and parasites. Selected use of microbiologic assays to detect these pathogens is encouraged. When tests are ordered non-judiciously, costs rapidly accrue. The age of the patient, time of year, travel history, and clinical presentation all provide clues to the etiologic agent. Microbiologic assays should be used judiciously to confirm or exclude the likely infectious agents.

Isolation of Campylobacter species from zoo animals and polymerase chain reaction-based random amplified polymorphism DNA analysis

A total of 104 fecal specimens from 30 mammals, 12 birds, and 3 reptiles at the Phoenix Zoological Gardens, Miyazaki City, Japan, were examined for the presence of Campylobacter species. All the animals examined were healthy with no fecal abnormality. Twenty-three (22.1%) thermophilic campylobacters, (9 C. jejuni, 11 C. hyointestinalis, 2 C. coli, and 1 C. lari), were isolated from 11 animals (7 mammals and 4 birds). C. jejuni and C. hyointestinalis were the predominant species isolated from these zoo animals and C. hyointestinalis was isolated frequently from simians. As selective media influence the numbers and species of campylobacters isolated, the agar medium was not supplemented with cephalothin. Campylobacters were isolated most frequently when a combination of enrichment culture and selective agar plating was performed at 42 degrees C. For the epidemiological study, a polymerase chain reaction (PCR)-based randomly amplified polymorphic DNA (RAPD) method was used as a tool to detect the heterogeneity of amplified DNAs of Campylobacter spp. isolated from zoo animals. The two arbitrary primers used in this study enabled even closely related strains of the same Campylobacter spp. to be differentiated. RAPD analysis revealed considerable diversity among the strains, suggesting that the transmission of Campylobacter spp. among animals in a defined area occurred through different mechanisms. Examination of the genotypic diversity among the multiple clones from the same host also revealed differences between clones. These results demonstrate that campylobacter populations in zoo animals are highly divergent.

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.

PCR detection, identification to species level, and fingerprinting of Campylobacter jejuni and Campylobacter coli direct from diarrheic samples

Three sets of primers were designed for PCR detection and differentiation of Campylobacter jejuni and Campylobacter coli. The first PCR assay was designed to coidentify C. jejuni and C. coli based on their 16S rRNA gene sequences. The second PCR assay, based on the hippuricase gene sequence, identified all tested reference strains of C. jejuni and also strains of that species which lack detectable hippuricase activity. The third PCR assay, based on the sequence of a cloned (putative) aspartokinase gene and the downstream open reading frame, identified all tested reference strains of C. coli. The assays will find immediate application in the rapid identification to species level of isolates. The assays combine with a protocol for purification of total DNA from fecal samples to allow reproducible PCR identification of campylobacters directly from stools. Of 20 clinical samples from which campylobacters had been cultured, we detected C. jejuni in 17, C. coli in 2, and coinfection of C. jejuni and Campylobacter hyointestinalis in 1. These results were concordant with culture and phenotypic identification to species level. Strain typing by PCR-restriction fragment length polymorphism of the flagellin (flaA) gene detected identical flaA types in fecal DNA and the corresponding campylobacter isolate. Twenty-five Campylobacter-negative stool samples gave no reaction with the PCR assays. These PCR assays can rapidly define the occurrence, species incidence, and flaA genotypes of enteropathogenic campylobacters.

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.

Prevalence of cytolethal distending toxin production in Campylobacter jejuni and relatedness of Campylobacter sp. cdtB gene

Campylobacter jejuni produces a toxin called cytolethal distending toxin (CDT). The genes encoding this toxin in C. jejuni 81-176 were cloned and sequenced. The nucleotide sequence of the genes revealed that there are three genes, cdtA, cdtB, and cdtC, encoding proteins with predicted sizes of 30,11-6, 28,989, and 21,157 Da, respectively. All three proteins were found to be related to the Escherichia coli CDT proteins, yet the amino acid sequences have diverged significantly. All three genes were required for toxic activity in a HeLa cell assay. HeLa cell assays of a variety of C. jejuni and C. coli strains suggested that most C. jejuni strains produce significantly higher CDT titers than do C. coli strains. Southern hybridization experiments demonstrated that the cdtB gene is present on a 6.0-kb ClaI fragment in all but one of the C. jejuni strains tested; the cdtB gene was on a 6.9-kb ClaI fragment in one strain. The C. jejuni 81-176 cdtB probe hybridized weakly to DNAs from C. coli strains. The C. jejuni 81-176 cdtB probe did not hybridize to DNAs from representative C. fetus, C. lari, C. "upsaliensis," and C. hyointestinalis strains, although the HeLa cell assay indicated that these strains make CDT. PCR experiments indicated the probable presence of cdtB sequences in all of these Campylobacter species.

Isolation of a restriction-less mutant and development of a shuttle vector for the genetic analysis of Campylobacter hyointestinalis

A cosmid shuttle cloning vector, pCHI15, was constructed which could be mobilized from Escherichia coli K-12 to a putative restriction-less mutant of Campylobacter hyointestinalis, C. fetus subsp. fetus, and C. fetus subsp. venerealis at a frequency of 10(-4) transconjugants per donor. A previously described C. coli shuttle vector, pILL550, could not be mobilized into the C. hyointestinalis restriction-less mutant, implying that the C. coli replicon was not functional in a C. hyointestinalis host. The type strains of C. jejuni, C. coli, C. fetus subsp. fetus, and C. hyointestinalis were analysed for their ability to be transformed by plasmid DNA which had been modified by other Campylobacter species. Each Campylobacter species was found to be most efficiently transformed by plasmid DNA that had been previously passaged in the same species. pCHI15 could be mobilized from C. coli into C. fetus subsp. fetus and the putative restriction-less mutant of C. hyointestinalis at a frequency of 3.0 x 10(-4) and 2.5 x 10(-3) transconjugants per donor, respectively.

Two cases of Campylobacter mucosalis enteritis in children

Two cases of Campylobacter mucosalis enteritis in children are reported. The patients recovered without antimicrobial therapy. Strains were isolated only by the feces filtration technique. In one child, bactericidal antibodies to the homologous strain were detected in a convalescent-phase serum sample. C. mucosalis should be considered a primary intestinal pathogen.

Presence of methylated adenine in GATC sequences in chromosomal DNAs from Campylobacter species

We digested chromosomal DNAs from 12 Campylobacter strains (C. jejuni, 4 strains; C. coli, 2 strains; C. fetus subsp. fetus, 2 strains; C. hyointestinalis, 2 strains; and C. upsaliensis, 2 strains) and from 4 Helicobacter strains (H. pylori, 2 strains; and H. mustelae, 2 strains) with HindIII, SstI, BamHI, DpnI, MboI, and Sau3AI. Restriction fragments were then separated by electrophoresis in 1% agarose or 10% polyacrylamide gels. Only DNAs from three Campylobacter species (C. jejuni, C. coli, and C. upsaliensis) were digested with DpnI (an enzyme that recognizes only methylated adenine in GATC sequences). We used MboI and Sau3AI to confirm these findings.

Uncommon Campylobacter species in infant Macaca nemestrina monkeys housed in a nursery

Studies were conducted to characterize 18 isolates of Campylobacter spp. that could not be identified as either Campylobacter jejuni or C. coli. The isolates were cultured from specimens from 13 of 18 infant nonhuman primates during a prospective epidemiologic study reported previously. Phenotypic tests, DNA hybridization, and analysis of DNA coding for rRNA identified the isolates as C. butzleri (seven isolates), C. hyointestinalis (seven isolates), and C. fetus subsp. fetus or C. fetus subsp. fetus-like organisms (four isolates). Ribotype and polyacrylamide gel electrophoresis patterns indicated that there was heterogeneity among the isolates of C. butzleri and C. fetus subsp. fetus-like organisms.

Pulsed-field gel electrophoresis for epidemiologic studies of Campylobacter hyointestinalis isolates

Campylobacter hyointestinalis was isolated from five members of the same family who had previously consumed raw milk. Pulsed-field gel electrophoresis of genomic DNAs from the five strains, after digestion with restriction endonuclease SalI, revealed that three strains had identical genome patterns and therefore appeared to be related, whereas the other two had completely different genome patterns and appeared to be unrelated. We report here for the first time the isolation of C. hyointestinalis from family members who had consumed raw milk. Our study also demonstrates the usefulness of pulsed-field gel electrophoresis for epidemiologic studies of this unusual campylobacter.

In vitro susceptibilities of aerotolerant Campylobacter isolates to 22 antimicrobial agents

We evaluated the in vitro activities of 22 antimicrobial agents against 78 human and animal isolates belonging to two aerotolerant Campylobacter species, C. cryaerophila and C. butzleri, using a broth microdilution technique. An additional 10 antimicrobial agents were included at concentrations found in selective Campylobacter media. Strains of C. cryaerophila belonged to two DNA hybridization groups: DNA hybridization group 1A, which includes the type strain of C. cryaerophila, and DNA hybridization group 1B. The aminoglycosides, fluoroquinolones, and one tetracycline (minocycline) demonstrated the most activity against all DNA hybridization groups (C. cryaerophila DNA groups 1A and 1B and C. butzleri). Most isolates were resistant to cephalosporin antibiotics, with the exception of cefotaxime, and were variably susceptible to trimethoprim-sulfamethoxazole. C. cryaerophila DNA hybridization group 1A isolates were generally susceptible to the tetracyclines, chloramphenicol, nalidixic acid, azithromycin, erythromycin, and roxithromycin and moderately susceptible to clindamycin, trimethoprim-sulfamethoxazole, ampicillin, and ampicillin-sulbactam. The MICs of tetracyclines were higher for C. butzleri and C. cryaerophila DNA hybridization group 1B isolates than for C. cryaerophila DNA hybridization group 1A isolates, but most strains were still susceptible to doxycycline and tetracycline; all isolates were susceptible to minocycline. C. butzleri and C. cryaerophila DNA hybridization group 1B isolates were generally resistant to the macrolide antibiotics (including erythromycin), chloramphenicol, clindamycin, nalidixic acid, ampicillin, and trimethoprim-sulfamethoxazole. Differences in antimicrobial susceptibility between aerotolerant Campylobacter species and more common Campylobacter species, e.g., C. jejuni, suggest that different treatment strategies may be necessary. Strains of all three DNA hybridization groups of aerotolerant Campylobacter isolates were susceptible to colistin, polymyxin B, and rifampin at concentrations commonly used in selective media. These results suggest that primary isolation methods for Campylobacter species may need to be modified to include aerotolerant Campylobacter strains.