Survey of Campylobacter spp. in owned and unowned dogs and cats in Northern Italy

Campylobacter occurrence and antimicrobial resistance profile in under five-year-old diarrheal children, backyard farm animals, and companion pets

Campylobacteriosis disproportionately affects children under five in low-income countries. However, epidemiological and antimicrobial resistance (AMR) information at the children-animal interface is lacking. We hypothesized that Campylobacter is a major cause of enteritis in children in Ethiopia, and contact with animals is a potential source of transmission. The objective of the study was to determine Campylobacter occurrence and its AMR in children under five with diarrhea, backyard farm animals, and companion pets. Stool from 303 children and feces from 711 animals were sampled. Campylobacter was isolated through membrane filtration on modified charcoal cefoperazone deoxycholate agar plates under microaerobic incubation, and the technique showed to be feasible for use in regions lacking organized laboratories. Typical isolates were characterized with MALDI-TOF MS and multiplex PCR. Of 303 children, 20% (n = 59) were infected, with a higher proportion in the 6 to 11-month age group. Campylobacter occurred in 64% (n = 14) of dogs and 44% (n = 112) of poultry. Campylobacter jejuni was present in both a child and animal species in 15% (n = 23) of 149 households positive for Campylobacter. MICs using the gradient strip diffusion test of 128 isolates displayed resistance rates of 20% to ciprofloxacin and 11% to doxycycline. MICs of ciprofloxacin and doxycycline varied between C. coli and C. jejuni, with higher resistance in C. coli and poultry isolates. Campylobacter infection in children and its prevalent excretion from backyard poultry and dogs is a understudied concern. The co-occurrence of C. jejuni in animals and children suggest household-level transmission As resistance to ciprofloxacin and doxycycline was observed, therapy of severe campylobacteriosis should consider susceptibility testing. Findings from this study can support evidence-based diagnosis, antimicrobial treatment, and further investigations on the spread of AMR mechanisms for informed One Health intervention.

Prevalence and antimicrobial resistance of Campylobacter species in shelter-housed healthy and diarrheic cats and dogs in Turkey

BACKGROUND

Campylobacter spp. are among the leading foodborne bacterial pathogens. Pet animals may be an important reservoir for human infection.

OBJECTIVES

To determine the prevalence and antimicrobial resistance profiles and mechanisms of Campylobacter isolates recovered from shelter-housed healthy and diarrheic cats and dogs in Erzurum province in Turkey.

METHODS

A total of 250 rectal swabs (from 124 cats and 126 dogs) collected between 2020 and 2021 were included in this study. The samples were cultured using a Campylobacter-selective agar medium. A single suspect colony from each plate was purified and species identification was performed by PCR. Minimum inhibitory concentration (MIC) values were determined against eight antibiotics. Specific antimicrobial resistance genes (tetO and aphA-3) and mutations (in gyrA) were screened by PCR and/or sequencing.

RESULTS

A total of 26 (10.4%) isolates (25 Campylobacter jejuni and 1 Campylobacter coli) were obtained from the dogs; no Campylobacter was isolated from the cats. Of the C. jejuni isolates, 19.2% were resistant to nalidixic acid, 7.7% to ciprofloxacin and 3.8% to tetracycline and gentamicin per the CLSI interpretative criteria. The C. coli isolate was susceptible to all of the tested antibiotics. Thr-86-Ile mutation was the most common change detected in the gyrA gene in the quinolone-resistant isolates.

CONCLUSION

While geographic and population differences exist, Campylobacter carriage and associated antibiotic resistance in dogs is common, emphasising the need for continuous surveillance in this species, particularly given its zoonotic potential.

Parasites and zoonotic bacteria in the feces of cats and dogs from animal shelters in Carinthia, Austria

Due to their close associations with humans, dogs and cats can be important reservoirs for zoonotic pathogens. In the current study 200 fecal samples of dogs (n = 70 samples) and cats (n = 130 samples) from animal shelters in Carinthia, southern Austria, were examined for the presence of parasites (fecal flotation and larval migration assay) and selected bacteria. Overall, 17.1% of the canine and 38.5% of the feline samples were positive for parasites (p < 0.001), most commonly Giardia duodenalis (dogs and cats), including potentially zoonotic genotypes revealed by multilocus genotyping, and Toxocara cati (cats). Cryptosporidium (C. felis), Cystoisospora spp. (dogs and cats), hookworms (dog), Trichuris (dog) Capillaria hepatica (cats), taeniids (cat), and Aelurostrongylus abstrusus (cat) were also found. Zoonotic bacteria were detected in 10.5% of the samples, Salmonella enterica (dogs), Campylobacter jejuni (dogs and cats) and Yersinia enterocolitica (cat) and were significantly associated with parasite infections in cats but not in dogs. Samples that were positive for several pathogens were common; especially G. duodenalis and T. cati were frequently found in association with each other, other parasites or bacteria. The spectrum of detected pathogens is comparable to that of other dog and cat populations in central Europe. However, since animals from shelters are frequently rehomed, diagnostic measures, appropriate hygiene and therapy as well as training of shelter staff are recommended to prevent zoonotic transmission of enteropathogens to staff or new owners. The presence of heteroxenic parasites, i.e. Aelurostrongylus abstrusus and Taenia taeniaeformis, and spurious excretion of Ca. hepatica in cats, indicates that these animals preyed on intermediate hosts, and that biosafety measures in pet shelters need to be evaluated for their efficacy in the prevention of pathogen transmission.

Molecular Prevalence and Risk Factors of Campylobacter Infection in Puppies in the Nairobi Metropolitan Region, Kenya

Campylobacter species are widely distributed pathogens; however, data on its epidemiology in puppies remain scanty, especially in Kenya. A cross-sectional study was conducted in the Nairobi Metropolitan Region to determine molecular prevalence and associated risk factors of Campylobacter species infection in puppies. A total of 260 rectal swabs were collected from puppies from breeding kennels, shelters, and the University of Nairobi Veterinary Teaching and Referral Hospital. The samples were subjected to polymerase chain reaction (PCR) assays for identification of Campylobacter species. Data on potential risk factors associated with puppy exposure were collected using a semistructured questionnaire. Multivariable mixed effects logistic regression analyses were performed with kennels as random effects. Campylobacter species were detected in 64 of the 260 sampled puppies yielding an overall prevalence of 24.6%. Multivariable results showed that puppies from shelters, puppies from kennels that are washed daily, puppies with a recent history of vomiting, and those treated with antibiotics in the past month were significantly associated with the presence of Campylobacter species. Being a kenneled puppy and having had concurrent bacterial infections were identified as protective factors. This study provides molecular evidence of puppy exposure to Campylobacter species which could have impact on puppy health and highlights the need to develop awareness and management strategies to potentially reduce the risk of transmitting this pathogen among puppies, to humans, and other animals.

Genomic Diversity of Campylobacter lari Group Isolates from Europe and Australia in a One Health Context

Members of the Campylobacter lari group are causative agents of human gastroenteritis and are frequently found in shellfish, marine waters, shorebirds, and marine mammals. Within a One Health context, we used comparative genomics to characterize isolates from a diverse range of sources and geographical locations within Europe and Australia and assess possible transmission of food, animal, and environmental isolates to the human host. A total of 158 C. lari isolates from Australia, Denmark, France, and Germany, which included 82 isolates from human stool and blood, 12 from food, 14 from domestic animal, 19 from waterbirds, and 31 from the environment were analyzed. Genome-wide analysis of the genetic diversity, virulence, and antimicrobial resistance (AMR) traits was carried-out. Most of the isolates belonged to C. lari subsp. lari (Cll; 98, 62.0%), while C. lari subsp. concheus and C. lari urease-positive thermotolerant Campylobacter (UPTC) were represented by 12 (7.6%) and 15 (9.5%) isolates, respectively. Furthermore, 33 (20.9%) isolates were not assigned a subspecies and were thus attributed to distant Campylobacter spp. clades. Whole-genome sequence-derived multilocus sequence typing (MLST) and core-genome MLST (cgMLST) analyses revealed a high genetic diversity with 97 sequence types (STs), including 60 novel STs and 14 cgMLST clusters (≤10 allele differences), respectively. The most prevalent STs were ST-21, ST-70, ST-24, and ST-58 (accounting for 13.3%, 4.4%, 3.8%, and 3.2% of isolates, respectively). A high prevalence of the 125 examined virulence-related loci (from 76.8 to 98.4% per isolate) was observed, especially in Cll isolates, suggesting a probable human pathogenicity of these strains. IMPORTANCE Currently, relatedness between bacterial isolates impacting human health is easily monitored by molecular typing methods. These approaches rely on discrete loci or whole-genome sequence (WGS) analyses. Campylobacter lari is an emergent human pathogen isolated from diverse ecological niches, including fecal material from humans and animals, aquatic environments, and seafood. The presence of C. lari in such diverse sources underlines the importance of adopting an integrated One Health approach in studying C. lari population structure for conducting epidemiological risk assessment. This retrospective study presents a comparative genomics analysis of C. lari isolates retrieved from two different continents (Europe and Australia) and from different sources (human, domestic animals, waterbirds, food, and environment). It was designed to improve knowledge regarding C. lari ecology and pathogenicity, important for developing effective surveillance and disease prevention strategies.

Prevalence and whole-genome sequence analysis of Campylobacter spp. strains isolated from wild deer and boar in Japan

As a part of risk analysis for consumption of meat from wild animals, the prevalence of Campylobacter spp. in wild deer and boar in Japan was investigated. C. hyointestinalis subsp. hyointestinalis (C. hyointestinalis) was isolated from 2.8% (7/253) of the wild deer and 22.1% (71/321) of the wild boar examined. All 23 wild deer isolates and 141 (72.7%) wild boar isolates carried both chcdt-I and chcdt-II genes. The remaining 53 (27.3%) wild boar isolates had only the chcdt-II gene. By whole-genome sequence analysis, we detected 38-40 virulence- and survival-associated genes (motility, chemotactic, adhesion, invasion, toxin, glycosylation, iron uptake, drug resistance, and stress response), which had been identified in C. jejuni and C. coli. In conclusion, our study highlights C. hyointestinalis as a possible cause of food-borne disease in humans and emphasizes the importance of food hygiene in the processing of wild meats for human consumption.

Prevalence, co-infection and seasonality of fecal enteropathogens from diarrheic cats in the Republic of Korea (2016-2019): a retrospective study

Background

Diarrhea is one of the most common clinical symptoms in cats and can be caused by infectious pathogens and investigation of the prevalence, co-infection and seasonality of enteropathogens are not well-established in diarrheic cats.

Results

Fecal samples of 1620 diarrheic cats were collected and enteropathogens were detected using real-time PCR. We retrospectively investigated the clinical features, total/seasonal prevalence, and infection patterns of enteropathogens. The positive infection rate was 82.59%. Bacterial, viral, and protozoal infections accounted for 49.3, 37.57, and 13.13% of cases, respectively. Feline enteric coronavirus (FECV) was the most common pathogen (29.37%), followed by Clostridium (C.) perfringens, Campylobacter (C.) coli, feline parvovirus, and Tritrichomonas foetus. The seasonality of enteropathogens was observed with peaks as follows: bacterial infections peaked in October, viral infections peaked in November, and protozoal infections peaked in August. Viral and protozoal infections showed differences in prevalence according to patient age. In the infection patterns, the ratios of single infections, mixed infections, and co-infections were 35.72, 9.87, and 54.41%, respectively. FECV was predominant in single infections. The most common patterns of multiple infections were C. perfringens and C. coli in mixed infections and C. perfringens and FECV in co-infections.

Conclusions

Infection patterns differed according to the enteropathogen species, seasonality, and age distribution in cats. The results of this study might be helpful to understand in clinical characteristics of feline infectious diarrhea. In addition, continued monitoring of feline enteropathogens is required.

Campylobacter jejuni in Different Canine Populations: Characteristics and Zoonotic Potential

With most epidemiological studies focused on poultry, dogs are often overlooked as a reservoir of Campylobacter, even though these animals maintain close daily contact with humans. The present study aimed to obtain a first insight into the presence and characteristics of Campylobacter spp. in different canine populations in Portugal, and to evaluate its zoonotic potential through genomic analysis. From a total of 125 rectal swabs collected from companion (n = 71) and hunting dogs (n = 54) living in two different settings, rural (n = 75) and urban (n = 50), 32 Campylobacter spp. isolates were obtained. Four different Campylobacter species were identified by Multiplex PCR and MALDI-TOF mass spectrometry, of which Campylobacter jejuni (n = 14, 44%) was overall the most frequently found species. Relevant resistance phenotypes were detected in C. jejuni, with 93% of the isolates being resistant to ciprofloxacin, 64% to tetracycline, and 57% to ampicillin, and three isolates being multi-drug-resistant. Comparison of the phenotypic and genotypic traits with human isolates from Portuguese patients revealed great similarity between both groups. Particularly relevant, the wgMLST analysis allowed the identification of isolates from human and dogs without any apparent epidemiological relationship, sharing high genetic proximity. Notwithstanding the limited sample size, considering the high genomic diversity of C. jejuni, the genetic overlap between human and dog strains observed in this study confirmed that the occurrence of this species in dogs is of public health concern, reinforcing the call for a One Health approach.

Presence of Campylobacterjejuni and C. coli in Dogs under Training for Animal-Assisted Therapies

This study was conducted to evaluate the presence of Campylobacter (C.) jejuni and C. coli in dogs at five dog training centers in Southern Italy. A total of 550 animals were sampled by collecting rectal swabs. The samples were processed to detect thermotolerant Campylobacter spp. by culture and molecular methods. Campylobacter spp. were isolated from 135/550 (24.5-95% confidence interval) dogs. A total of 84 C. jejuni (62.2%) and 51 C. coli (37.8%) isolates were identified using conventional PCR. The dog data (age, sex, breed, and eating habits) were examined by two statistical analyses using the C. jejuni and C. coli status (positive or negative) as dependent variables. Dogs fed home-cooked food showed a higher risk of being positive for C. jejuni than dogs fed dry or canned meat for dogs (50.0%; p < 0.01). Moreover, purebred dogs had a significantly higher risk than crossbred dogs for C. coli positivity (16.4%; p < 0.01). This is the first study on the prevalence of C. jejuni and C. coli in dogs frequenting dog training centers for animal-assisted therapies (AATs). Our findings emphasize the potential zoonotic risk for patients and users involved in AATs settings and highlight the need to carry out ad hoc health checks and to pay attention to the choice of the dog, as well as eating habits, in order to minimize the risk of infection.

Dogs and Cats: Reservoirs for Highly Diverse Campylobacter jejuni and a Potential Source of Human Exposure

Assessing the carriage of Campylobacter in animal reservoirs is essential to better understand Campylobacter epidemiology. Here, we evaluated the prevalence of thermophilic Campylobacter spp. in dogs and cats, hereafter defined as pets, and characterized Campylobacter jejuni (C. jejuni) isolates to assess their genetic diversity and their potential link with isolates from other animals or human cases. During a 6-month period, 304 feces samples were collected from pets. A significantly higher prevalence of thermophilic Campylobacter spp. was found in dogs compared with cats, as well as in dogs ≤ 1-year-old compared with older dogs. C. jejuni was the predominant species found in pets, and its genomic characterization revealed a high genetic diversity. Genotypes comparison with previously characterized isolates revealed a partial overlap between C. jejuni isolates from pets, chicken, cattle, and clinical cases. This overlap suggests the potential role of livestock and humans in pets' exposure to Campylobacter, or vice versa. The isolation of pets' specific profiles may suggest the existence of other sources of pet contamination or imply that pets may constitute a reservoir for Campylobacter. Because of the proximity between humans and pets, along with their frequent carriage of C. jejuni, human exposure to Campylobacter from pets can be more important than previously thought.

Complete genome sequence and comparative genomic analysis of hyper-aerotolerant Campylobacter lari strain SCHS02 isolated from duck for its potential pathogenicity

Campylobacter lari strain SCHS02, a novel hyper-aerotolerant strain that survives under aerobic conditions, was isolated from retail duck meat. The genome is a single chromosome of 1,520,838 base pairs, with a mean GC content of 29.7%. It harbors 1546 protein-coding sequences and 45 tRNA and 9 rRNA genes. Genes associated with the oxidative stress response, including perR, bcp, ahpC, and sodB, were identified in the genome. Furthermore, 68 virulence-related genes were identified and sorted into 9 classes and 14 subclasses. The virulence gene profile of SCHS02 was similar to those of two human clinical C. lari isolates. Comparative genomic analysis of strain SCHS02 and 18 C. lari strains retrieved from a public database revealed the core and accessory gene profiles of C. lari strains, as well as putative core gene involved in halotolerance. Phylogenetic analysis revealed that strain SCHS02 is genetically related to isolates from bird samples and human clinical isolates, rather than to isolates from other environmental sources. These findings reveal essential genomic information about the newly identified hyper-aerotolerant C. lari strain isolated from a duck source, providing a basis for future studies of the strain considering its potential threat to public health and further research of the pathogenicity of C. lari.

Prevalence and risk factors associated with Campylobacter spp. occurrence in healthy dogs visiting four rural community veterinary clinics in South Africa

Reports on the occurrence of Campylobacter spp. in dogs in South Africa are non-existent. This study investigated the prevalence of Campylobacter spp. in 481 dogs visiting four rural community veterinary clinics in South Africa. Dogs were screened for Campylobacter spp. by culture and polymerase chain reaction (PCR), and logistic regression analysis was performed to assess the association between sex, clinic, breed and age and the occurrence of Campylobacter spp. in dogs. The prevalence of Campylobacter spp. was 41.50% (95% confidence interval [CI], 37.39% - 46.04%). Campylobacter jejuni, C. upsaliensis and C. coli were detected in 29.31% (95% CI, 25.42% - 33.54%), 13.10% (95% CI, 10.37% - 16.42%) and 5.41% (95% CI, 3.71% - 7.82%) of dogs, respectively. Dogs carrying more than one species of Campylobacter spp. accounted for 6.23% (95% CI, 4.40% - 8.78%). Campylobacter upsaliensis and C. jejuni were detected in 3.74% (95% CI, 2.37% - 5.86%), whereas C. coli and C. jejuni were found in 2.49% (95% CI, 1.42% - 4.34%) of dogs. Age and clinic were the risk factors significantly associated with Campylobacter spp. occurrence, while age, breed and clinic were predictors of C. jejuni carriage. Furthermore, age was the only risk factor associated with a higher likelihood of carrying C. upsaliensis. The prevalence of Campylobacter spp. C. jejuni and C. upsaliensis increased significantly as dogs grew older. In addition, the odds of carrying Campylobacter spp. were higher in the Staffordshire bull terrier breed compared to crossbreed dogs. In conclusion, this study shows that dogs visiting rural community veterinary clinics in South Africa are reservoirs of Campylobacter spp. and may be potential sources of Campylobacter spp. for humans living in close proximity of the dog populations under study.

Prevalence, associated risk factors and antimicrobial susceptibility pattern of Campylobacter species among dogs attending veterinary practices at Veterinary University, Mathura, India

Campylobacteriosis is among the leading bacterial causes of human gastroenteritis all over the world and most of the isolates are resistant to different antibacterials. Pet rearing has been identified as a risk factor for Campylobacter infection in humans. The study was conducted to determine the prevalence of faecal Campylobacter shedding among dogs, to estimate the specific prevalence of Campylobacter jejuni shedding, to identify the associated risk factors and antimicrobial susceptibility pattern of Campylobacter spp. in dogs attending veterinary practice at Veterinary University, Mathura, India. Rectal swabs were aseptically collected and incubated using selective media and species isolation was further processed following standard protocols. In addition, genus and species specific polymerase chain reaction (PCR) was performed for species differentiation. A total of 134 dogs were included in this study. Among 134 faecal samples cultured, 38 samples (28.36%) were positive for Campylobacter species. C. jejuni was the most prevalent isolate in dogs. Breed, age, clinical signs of diarrhea and habitat sharing had statistically significant association with Campylobacter shedding. On drug sensitivity assay with 19 commonly used antibacterials 100% resistance was shown against amoxycillin, ampicillin, aztreonam, cefotaxim, lincomycin, oxytetracycline, penicillin, streptomycin and tetracycline. It was followed by pefloxacin (92.11%), chloramphenicol (86.84%), ciprofloxacin (84.21%), nitrofurazone (78.94%), ofloxacin (76.32%), norfloxacin (73.68%) and cefaclor (73.68%). The results of the present study revealed high prevalence of Campylobacter spp. among dogs. The prevalence was higher in dogs of nondescript breed, pups and dogs sharing their habitat. The antimicrobial resistance patterns showed a high rate of multi drug resistant isolates in the dog population. Therefore, awareness in handling of dogs is important to prevent the zoonotic transmission of bacteria from pets to human beings especially in children and immunocompromised patients.

Prevalence of most common human pathogenic Campylobacter spp. in dogs and cats in Styria, Austria

The aim of this study was to determine the frequency of occurrence of most common human pathogenic Campylobacter species, Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli), in dogs and cats in Styria, Austria. In the period from April 2010 to April 2012, 842 faecal samples from dogs and cats from Styria, Austria were examined for Campylobacter (C.) species (spp.). All samples were subjected to qualitative microbiological culture testing, and additionally, some of them have been studied using qualitative real‐time PCR. In microbiological culture, 5.9% of all samples investigated were C. spp. positive. With 3.1% out of positive samples, C. jejuni was the most common type. Campylobacter upsaliensis (C. upsaliensis) was detected only in 0.5% of the samples. The remaining positive samples (2.4%) were classified as C. species (sp.). C. coli could not be found in any of the samples. A higher prevalence of C. jejuni was found in kittens with 14.3% and in diarrhoeic dogs (7.4%) and cats (23.8%). The real‐time PCR revealed for dogs and cats together, 27% of C. jejuni‐positive faecal and 8% positive faecal swap samples. The obtained C. jejuni strains underwent antibiotic resistance testing using three different tests (agar diffusion, MIC testing and E‐test) with different numbers of antibiotics. From the antibiotics used in this study, several showed high test‐dependent resistance rates (cephalexin, cefovecin, kanamycin, sulfamethoxazole/trimethoprim, penicillin G, ciprofloxacin, enrofloxacin, marbofloxacin, nalidixic acid). Overall, the prevalence of C. spp. in this study was very low compared to others, with the exception of C. jejuni in kittens and diarrhoeic animals. The results of the real‐time PCR suggest that the rate of colonization of C. jejuni was actually higher than the results of the culture showed. As the resistance rates of C. jejuni isolates partly were very high, possible transmission of (multi‐) resistant C. jejuni strains to humans especially from kittens and diarrhoeic animals must be expected.

Raw Meat-Based Diets in Dogs and Cats

Feeding pets raw meat-based diets (RMBDs) is commonly practiced by many companion animal owners and has received increasing attention in recent years. It may be beneficial for the animals, but may also pose a health risk for both pets and their owners, as RMBDs may be contaminated by enteric pathogens-such as Campylobacter, Salmonella, and Yersinia-which are the most common zoonotic bacteria causing enteritis in humans. Little information exists on the prevalence of these pathogens in pet food, and thus one aim was to investigate the prevalence of Campylobacter, Salmonella, and Yersinia in commercial RMBDs from retail stores. Little evidence also exists on the significance of raw meat feeding on the shedding of Campylobacter, Salmonella, and enteropathogenic Yersinia in the feces of pets, and therefore, the second goal was to study the presence of these pathogens in dogs and cats fed RMBDs. Polymerase chain reaction (PCR) only sporadically detected Campylobacter, Salmonella, and enteropathogenic Yersinia in RMBDs. These pathogens were not found by culturing, indicating a low contamination level in frozen RMBDs. They were also detected in the feces of dogs and cats, but the association with feeding RMBDs to them remained unclear.

Campylobacter upsaliensis isolated from dogs produces high titer of cytolethal distending toxin

Cytolethal distending toxin (CDT) consisting of CdtA, CdtB and CdtC has been reported to be a possible virulence factor of campylobacters including Campylobacter upsaliensis. In our previous study, the cdtB gene-based PCR-restriction fragment length polymorphism (RFLP) assay for detection and differentiation of 7 Campylobacter species yielded 3 different RFLP patterns (Cu-I to Cu-III). In this study, entire cdt (Cucdt) genes of each pattern were sequenced to see whether there are any differences in cdt genes, its amino acid sequences and biological activity of CuCDT. We found that all 3 representative strains harbor the entire Cucdt genes and homology between prototype and newly determined Cucdt genes was 94 to 98% with cdtA, 93 to 94% with cdtB and 92 to 93% with cdtC, while that between amino acids of CuCDT was 95 to 99% with CdtA, 97 to 98% with CdtB and 92 to 93% with CdtC. Furthermore, CDT activity produced by C. upsaliensis strains was examined by cytotoxicity assay with HeLa cells. Interestingly, C. upsaliensis produced 64 to 2,340 times higher CDT titer in comparison to other campylobacters did. In addition, Cu-III showed 64 times higher CDT titer than Cu-II, although CDT production level was almost the same by western blotting. These data suggest that CDT produced by C. upsaliensis might contribute more to human diseases in comparison to that produced by other campylobacters and Cu-III CDT seems to be more toxic to HeLa cells in comparison to Cu-I and Cu-II CDTs.