Prevalence of Campylobacter species in wild birds of South Korea

Campylobacter species cause human gastrointestinal infections worldwide. They commonly inhabit intestines of avian species including wild birds. They might play a role in the spread of infections to humans and other bird species. The prevalence of Campylobacter species in 2164 faecal samples of wild birds (representing 71 species and 28 families) captured across the Korean peninsula was evaluated in this study. The overall prevalence was 15.3% (332/2164). Bird species belonging to the family Charadriidae had the highest isolation rate (30.0%), followed by those belonging to the families Ardeidae (26.4%), Turdidae (21.9%), and Anatidae (15.3%). The prevalence of Campylobacter spp. differed significantly according to migratory habit. Stopover birds were the most commonly infected (19.0%), followed by winter migratory (16.7%) and summer migratory birds (12.3%). However, indigenous birds showed very low prevalence (2.7%). Antimicrobial susceptibility tests were performed for 213 isolates. Results showed that Campylobacter jejuni isolates (n?=?169) exhibited resistance to nalidixic acid (5.3%), ciprofloxacin (3.0%), and tetracycline (1.8%), while Campylobacter lari (n?=?1) displayed resistance to nalidixic acid and ciprofloxacin. However, all Campylobacter coli isolates (n?=?20) were susceptible to all antimicrobials tested. This is the first report on the prevalence of Campylobacter species in wild birds that seasonally or indigenously inhabit the Korean peninsula. Our results indicate that the overall prevalence of Campylobacter in wild birds is moderate. Therefore, birds might serve as significant reservoirs for Campylobacter pathogens.     

Use of a selective medium and a membrane filter method for isolation ofCampylobacter species from Spanish paediatric patients

A study was conducted to assess the value of a combination of two culture methods for isolation ofCampylobacter spp. from Spanish children. Seven hundred twenty-nine diarrhoea] stool specimens from 599 patients were examined forCampylobacter spp. by culturing them on charcoal cefoperazone deoxycholate agar and on blood agar with a membrane filter. One hundred sixteenCampylobacter strains were isolated from a total of 108 specimens; 75 (64.6%) wereCampylobacter jejuni, 32 (27.5%) wereCampylobacter coli, 8 (6.8%) were non-typeable, and one (0.9%) wasCampylobacter upsaliensis. Campylobacters were isolated from 99 positive samples using charcoal cefoperazone deoxycholate agar alone. The filtration technique alone yielded only 86 positive samples. Seven specimens yielded differentCampylobacter spp. with different media. The only catalase-negative strain was recovered using the filter method. The combination of the selective medium with the filter method increased the isolation rate ofCampylobacter strains by 14.1%. Isolation rates of campylobacters using the filter method were similar to those reported in European studies, in which a similar frequency ofCampylobacter upsaliensis was observed. The addition of a filter method for routine laboratory isolation of campylobacters should be considered in selected age groups (in children <10 years of age) or in areas where catalase-negative or weakly-positiveCampylobacter strains may be of epidemiological significance.     

Comparison of two selective media and a membrane filter technique for isolation ofCampylobacter species from diarrhoeal stools

Diarrhoeal stool specimens from 415 patients were examined forCampylobacter spp. by culture on charcoal cefoperazone deoxycholate agar (CCDA), Skirrow medium and Columbia blood agar overlaid with a 0.65 µm pore size membrane filter. Forty-eightCampylobacter strains were isolated from 45 (10.8 %) specimens by all media; 44 wereCampylobacter jejuni (91.7 %), three wereCampylobacter coli (6.3 %) and one wasCampylobacter hyointestinalis (2.0 %). The percentages ofCampylobacter-positive specimens isolated on Skirrow medium, CCDA and the membrane filter were 62, 82 and 95 %, respectively. The recovery of moreCampylobacter spp. from the same stool sample was achieved by the membrane filter method only. The highest isolation rate (100 %) was observed when culture on CCDA and the membrane filter method were combined.     

Prevalence and antimicrobial resistance of Campylobacter jejuni and Campylobacter coli isolated from raw camel, beef, and water buffalo meat in Iran

This study was conducted to determine the prevalence and antimicrobial resistance of Campylobacter spp. isolated from retail raw meats in Iran. From August 2009 to August 2010, a total of 379 raw meat samples from camel (n?=?130), beef (n?=?207), and water buffalo (n?=?42) were purchased from randomly selected retail outlets in Chaharmahal va Bakhtiari and Khuzestan provinces in Iran. The samples were evaluated for the presence of Campylobacter using traditional bacteriological tests and a nested polymerase chain reaction. Overall, 31 of 379 meat samples (8.2%) were contaminated with Campylobacter. The highest prevalence of Campylobacter spp. was found in water buffalo meat (21.4%), followed by beef (9.2%), and camel (2.3%) meat. The most prevalent Campylobacter species isolated from meat samples was Campylobacter jejuni (77.4%); the remaining isolates were Campylobacter coli (22.6%). Susceptibilities of 31 Campylobacter isolates were determined for ten antimicrobial drugs using the disk diffusion assay. Of 31 Campylobacter isolates, 27 (87.1%) were resistant to one or more antimicrobial agents. Nine strains (29.0%) were resistant to one single antimicrobial agent, and eight strains (25.8%) showed resistance to two antimicrobial agents. Multidrug resistance was found in 32.3% of Campylobacter strains. Resistance to tetracycline was the most common finding (67.7%), followed by resistance to ciprofloxacin (32.7%), and nalidixic acid (32.7%). To the authors' knowledge, the present study is the first report of the isolation of Campylobacter spp. from raw water buffalo meat in Iran.     

Detection by PCR of eight groups of enteric pathogens in 4,627 faecal samples: re-examination of the English case-control Infectious Intestinal Disease Study (1993–1996)

The English case-control Infectious Intestinal Disease Study (1993–1996) failed to detect an enteric pathogen or toxin in 49% of cases of gastroenteritis. In the present study, polymerase chain reaction (PCR) assays were applied to DNA and cDNA generated from 4,627 faecal samples from cases and controls archived during the original study for the detection of norovirus, rotavirus, sapovirus, Campylobacter spp., Salmonella spp., enteroaggregative Escherichia coli, Cryptosporidium spp., and Giardia spp. The percentage of archived samples from cases and from controls in which at least one agent (or toxin) was detected increased from 53% in the original study to 75% and from 19 to 42%, respectively, after the application of PCR assays. Among cases, the following percentages of enteric pathogens were detected: norovirus 36%, rotavirus A 31%, sapovirus 4%, Salmonella spp. 6%, Campylobacter jejuni 13%, Campylobacter coli 2%, other Campylobacter spp. 8%, enteroaggregative E. coli 6%, Giardia spp. 2%, and Cryptosporidium spp. 2%. The present study provides additional insight into the aetiology of infectious intestinal disease in England and highlights the occurrence of viral infections in cases as well as in asymptomatic individuals. Other notable findings include the frequent presence of Campylobacter spp. other than C. jejuni or C. coli, the high frequency of multiple agents in 41% of cases and in 13% of controls, and the variation in the aetiology and rate of infection found for different age groups. The results demonstrate the greater sensitivity of PCR-based methods compared to current conventional methods.     

Prevalence of Campylobacter Enteritis in Children under 5 Years Hospitalised for Diarrhoea in Two Cities of Northeast India

Background: Campylobacter enteritis is the major cause of bacterial gastroenteritis worldwide. In recent years, there has been a rise in global incidence of campylobacteriosis. There are no available data on prevalence of Campylobacter diarrhoea from Northeast India. Materials and Methods: The study investigated archival stool samples collected between 2014 and 2016 from two hospitals of Northeast India. A total of 407 archival stool samples from cases of diarrhoea under 5 years of age were screened for Campylobacter spp. using commercial probe-based real-time polymerase chain reaction assay. Results: Campylobacter spp. was detected in overall 10.1% (41/407; 95% confidence interval: 7.4%–13.3%) in children under 5 years hospitalised for diarrhoea. The prevalence was significantly higher from Dibrugarh, Assam, compared to Dimapur, i.e., 13.4% (27/201) versus 6.8% (14/206), respectively (P = 0.02). Campylobacter detection was highest in the month of June and July compared to December and January (20%–18.8% vs. 8.9%–6.2%, respectively). Further, Campylobacter infection was higher in the age group below 24 months (11.7%) compared to above 24 months (7.0%). Campylobacter jejuni was detected in 80.5% of the positive cases. Conclusion: The present study reveals that Campylobacter infection is endemic in the studied regions of Northeast India and microbiological laboratories of the region should actively pursue the isolation or detection of Campylobacter spp. in cases of diarrhoea in routine stool cultures.     

Clinical Evaluation of a Real-Time PCR Assay for Identification of Salmonella,Shigella, Campylobacter (Campylobacter jejuni and C. coli), and Shiga Toxin-Producing Escherichia coli Isolates in Stool Specimens

Enteric illness affects millions of individuals annually in the United States and results in >50,000 hospitalizations. The rapid and accurate identification of bacterial pathogens associated with gastroenteritis can aid acute patient management decisions, including the use of antibiotic therapy and infection control. This study compared the ProGastro SSCS multiplex real-time PCR assay (Gen-Probe Prodesse, San Diego, CA) to culture for the identification of Campylobacter spp. (Campylobacter jejuni and Campylobacter coli), Salmonella spp., and Shigella spp. and to broth enrichment followed by an FDA-cleared enzyme immunoassay (EIA) for the identification of Shiga toxin-producing Escherichia coli (STEC) isolates in stool specimens. Stool samples submitted in preservatives for routine culture and EIA were prospectively enrolled and tested at four clinical centers. Discrepancies between the ProGastro SSCS assay and culture or EIA were resolved using bidirectional sequencing. The overall prevalence of the pathogens as detected by culture was 5.6% (1.8% Campylobacter, 1.8% Salmonella, 1.3% Shigella, and 0.8% STEC). When results based on the ProGastro SSCS assay and bidirectional sequencing were applied, the overall prevalence increased to 8.3% (2.3% Campylobacter, 2.6% Salmonella, 1.8% Shigella, and 1.6% STEC). Following resolution of the discrepant results, the sensitivity of the ProGastro SSCS assay was 100% for all pathogens, and the specificities ranged from 99.4% to 100%. The sensitivity of culture compared to sequence-confirmed ProGastro SSCS results ranged from 52.9% to 76.9%, with the specificities ranging from 99.9% to 100%. Overall, these results suggest that the ProGastro SSCS assay is highly sensitive and specific in a clinical setting.     

Occurrence and genotypes of Campylobacter species in broilers during the rearing period

Poultry are the main source of Campylobacter infection worldwide. To obtain information on Campylobacter-infected flocks and create a reference for preventing and controlling Campylobacter at farm level, Campylobacter isolates were recovered from broilers and the environments of nine chicken flocks in two farms during growth. The genetic relationship between the Campylobacter isolates was determined using multilocus sequence typing. Flocks were colonized as early as 3 weeks after introduction to the farm. The highest colonization rate was more than 90% and occurred 4–6 weeks after introduction to the farm. Quantitative data showed that the highest Campylobacter loads appeared at 1–2 weeks after initial colonization. Campylobacter loads in cloacal swabs in four flocks were significantly higher at 5 weeks than at 3 weeks (P?Campylobacter jejuni and eight for Campylobacter coli isolates. The STs of the Campylobacter isolates recovered from farm 1 were more diversified than those from farm 2. The STs of environmental samples were highly consistent with those of the cloacal swab samples. The consistency between Campylobacter STs in the environmental and cloacal swab samples suggested that the environment might be one of the main sources of infection. Thus, our study highlights the prevalence and contamination load of Campylobacter in broilers during their rearing period and emphasizes the need for control and prevention measures for Campylobacter infection in broilers, which is also important for human health.     

Prevalence of enteropathogenic bacteria in common quail (Coturnix coturnix)

The study was aimed at evaluating the prevalence of enteropathogenic bacteria (i.e. Campylobacter spp., shigatoxin-producing Escherichia coli, Salmonella spp.) in common quail (Coturnix coturnix). To achieve this goal, 70 common quails were collected during the hunting season in the Campania region (southern Italy). From each bird, cloacal swab samples were collected and subjected to culture methods, polymerase chain reaction and serotyping. The results of the present study showed a prevalence of 21.4% and 5.7% for Campylobacter spp. and shigatoxin-producing E. coli, respectively. In contrast, no Salmonella spp. was isolated. These findings show that common quail, as migratory birds, may constitute an environmental carrier of these pathogens representing a source of infection for other birds, livestock and humans.     

Comparison of a novel microaerobic system with three other gas-generating systems for the recovery ofCampylobacter species from human faecal samples

Three commercial gas-generating systems — CampyGen (Oxoid, UK), Oxoid BR56 (Oxoid, UK), and CampyPak Plus (Becton Dickinson, USA)—and the evacuation replacement technique were compared for the recovery ofCampylobacter spp. from 500 human faecal samples collected from patients with gastroenteritis. Four hundred fifty faecal samples were tested upon receipt in the laboratory. Fifty faecal samples that had been previously found to be positive forCampylobacter spp. were tested retrospectively; these had been stored at 4°C for more than 48 h. A total of 41 (9.1%) of the fresh faecal samples and 41 of 50 (82%) of the stored faecal samples were positive for thermophilic campylobacters. The CampyGen, the Oxoid BR56, the CampyPak Plus, and the evacuation replacement system detectedCampylobacter spp. in 40 (97.6%), 39 (95.1%), 41 (100%), and 41 (100%) of the positive fresh faecal samples and in 37 (90.2%), 40 (97.6%), 39 (95.1%), and 40 (97.6%) of the stored samples, respectively. There was no statistical difference in performance of any of the four gas systems used (p=0.98; chi-square test). Eighty-six percent of the isolates wereCampylobacter jejuni and 14% wereCampylobacter coll. Biotyping and phage typing of the isolates demonstrated that they were of a diverse range of subtypes. This study demonstrates that thermophilic campylobacters can be isolated from human diarrhoeal faecal samples using any of the four microaerobic-atmosphere-generating systems.     

Improved Detection of Bacterial Pathogens in Patients Presenting with Gastroenteritis by Use of the EntericBio Real-Time Gastro Panel I Assay

In this study, we evaluated the use of EntericBio real-time Gastro Panel I (Serosep, Limerick, Ireland) for routine use in a clinical microbiology laboratory for simultaneous detection of Campylobacter jejuni, coli, and lari, Shiga toxin-producing Escherichia coli (STEC), Salmonella spp., and Shigella spp. in feces. This system differs from its predecessor (the EntericBio Panel II system, Serosep) in that it allows real-time detection of pathogens directly from feces, without pre-enrichment. It also specifically detects Campylobacter jejuni, coli, and lari rather than all Campylobacter species, as is the case with the previous system. A total of 528 samples from patients presenting with acute gastroenteritis were screened prospectively with this assay, and results were compared with those of the current method, which combines screening the samples with a molecular assay (the EntericBio Panel II assay) and retrospective culture of the specimens in which the target was detected. Discrepancy analysis was conducted using culture and molecular methods. The real-time assay produced 84 positive results, specifically, Campylobacter spp. (n = 44); Stx1 and/or Stx2 (n = 35); Shigella spp. (n = 3); and Salmonella spp. (n = 6). Of these, 4 samples represented coinfections with Campylobacter spp. and STEC. The real-time assay showed an increased detection rate for pathogens, apart from Salmonella spp. Four Campylobacter-positive and 6 Stx-positive results remained unconfirmed by any other method used. The isolation rates for PCR-positive samples were as follows: Campylobacter spp., 80%; STEC, 45.7%; Salmonella spp., 100%; and Shigella spp., 66.7%. The sensitivity, specificity, positive predictive value, negative predictive value, and efficiency were 100%, 97.8%, 88.1%, 100%, and 98.1%, respectively.     

Description and sources of contamination by Campylobacter spp. of river water destined for human consumption in Brittany, France

Presence or absence of Campylobacter spp. in water of five rivers upstream from an intake point for drinking water production was investigated, and isolates genetically compared with human, pig and poultry isolates in order to determine their source. River water and drinking water obtained from these rivers were sampled one time per month, over a period of one year, and tested for Campylobacter. Isolates were typed by PFGE. Campylobacter was not detected in treated drinking water, but 50% of the river samples were contaminated. Contamination was observed on the four seasons. In total, 297 Campylobacter isolates were collected and generated 46 PFGE profiles. Campylobacter jejuni was the most frequently detected species in samples (74.1% of the isolates), followed by Campylobacter coli (17.8%) and Campylobacter lari (8.1%). Forty-two of the 46 PFGE profiles were unique. Only one genotype was detected three times in a river during the year and four genotypes in two different rivers. When compared to animal and human Campylobacter PFGE profiles, 14, 11 and one Campylobacter genotypes from water were genetically closed to human, poultry, and pig Campylobacter genotypes, respectively. The Campylobacter population displayed a high level of genetic diversity, suggesting that contamination originated from various origins. Human, poultry and pig were sources of contamination of the river by Campylobacter. Finally, no Campylobacter were detected in drinking water, indicating that the risk of outbreaks due to consumption of drinking water is low.     

Thermophilic Campylobacter spp. in Danish broiler production: A cross-sectional survey and a retrospective analysis of risk factors for occurrence in broiler flocks

In order to elucidate the rate of thermophilic Campylobacter spp. carriage in Danish broiler production and to identify risk factors for occurrence of campylobacter in broiler flocks, a total of 88 randomly selected broiler flocks were tested for campylobacter infection, and a subsequent study of risk factors based on a questionnaire was conducted. The sample material comprised cloacal swabs from live birds before slaughter, and neck skin samples from carcasses at the end of the processing line. A total of 52% of the flocks were found Campylobacter spp.-positive before slaughter. At the end of processing, 24% of the flocks were positive. The species distribution was 87% Campylobacter jejuni, 8% Campylobacter coli and 5% Campylobacter lari. The following parameters were identified as significant risk factors: lack of a hygiene barrier (odds ratio (OR) = 3.1, 1.1 < OR < 9.3), presence of animals in the vicinity of the broiler house on farms with a missing hygiene barrier (OR = 7.0, 1.6 < OR < 33.9), livestock other than chickens on farms with a missing hygiene barrier (OR = 7.6, 1.4 < OR < 44.9), dividing the flock into batches for staggered slaughter (OR = 6.8, 1.2 < OR < 49.3), a down period of less than 14 days (OR = 5.0, 1.2 < OR < 22.6), and feeding purchased wheat rather than home-grown wheat (OR = 3.1, 1.0 <OR < 9.9). The presence of a hygiene barrier was found to be the single most important biosecurity measure for production of campylobacter-free broilers.     

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.     

Detection of Campylobacter in human and animal field samples in Cambodia

Campylobacter are zoonotic bacteria and a leading cause of human gastroenteritis worldwide with Campylobacter jejuni and C. coli being the most commonly detected species. The aim of this study was to detect Campylobacter in humans and livestock (chickens, ducks, pigs, cattle, water buffalo, quail, pigeons and geese) in rural households by routine culturing and multiplex PCR in faecal samples frozen before analysis. Of 681 human samples, 82 (12%) tested positive by PCR (C. jejuni in 66 samples and C. coli in 16), but none by routine culture. Children were more commonly Campylobacter positive (19%) than adult males (8%) and females (7%). Of 853 livestock samples, 106 (12%) tested positive by routine culture and 352 (41%) by PCR. Campylobacter jejuni was more frequent in chickens and ducks and C. coli in pigs. In conclusion, Campylobacter proved to be highly prevalent by PCR in children (19%), ducks (24%), chickens (56%) and pigs (72%). Routine culturing was insufficiently sensitive in detecting Campylobacter in field samples frozen before analysis. These findings suggest that PCR should be the preferred diagnostic method for detection of Campylobacter in humans and livestock where timely culture is not feasible.     

Prevalence and antibiotic susceptibility of thermophilic Campylobacters from sources implicated in horizontal transmission of flock colonisation

Thermophilic Campylobacter are commonly associated with poultry as commensals of the avian gut and are the causative agent responsible for human Campylobacteriosis. This study aimed to establish the prevalence of Campylobacter spp. from environmental sources that have previously been implicated as sources of horizontal transmission. The highest prevalence of thermophilic Campylobacter was found in water samples (87.5%) and lowest from flies (7.2%). Only C. jejuni was isolated from all sources. A secondary aim was to provide a baseline of resistance profiles of Campylobacter spp. isolates obtained. Alarmingly all the C. jejuni isolates from environmental sources as well as humans were multi-drug resistant.     

Rapid detection ofCampylobacter jejuni andCampylobacter coli isolated from clinical specimens using the polymerase chain reaction

SeventeenCampylobacter strains isolated from 16 children hospitalised with acute diarrhea were analysed by in vitro enzymatic amplification using two sets of oligonucleotide primers specific forCampylobacter jejuni andCampylobacter coli, respectively. Thirteen strains (76 %) were identified asCampylobacter jejuni and four strains (24 %) asCampylobacter coli. Subsequent bacteriological identification confirmed the identity of the same 13Campylobacter jejuni strains and the 4Campylobacter coli strains. Thus, these PCR methods enabled rapid and specific detection of all theCampylobacter jejuni andCampylobacter coli strains without any false-positive or false-negative results.     

Phenotypic and genotypic differentiation of Campylobacter spp. isolated from Austrian broiler farms: A comparison

An identification scheme based on restriction fragment length polymorphism of polymerase chain reaction products (PCR-RFLP) was developed to differentiate isolates of the genera Campylobacter, Arcobacter and Helicobacter. Based on the 16S rRNA gene of these genera, PCR amplified a 1216-bp fragment. The amplicons were digested with the restriction enzymes RsaI and EcoRV. Additional differentiation was obtained using a PCR-assay based on the hippuricase gene. Genotyping was performed on several reference strains from the National Collection of Typing Culture (NCTC), London, and on 130 field isolates. In parallel, a phenotypic differentiation was performed, in order to compare the results. In 119 cases (91.5%) the results obtained from the genotypic characterization were concordant with those from phenotypic testing. Co-infections with Campylobacter jejuni and Campylobacter coli in two samples and seven hippurate-negative C. jejuni-strains were identified by the genotypic method. Furthermore, PCR-RFLP assays identified an atypical isolate as Campylobacter fetus/hyointestinalis.     

Identification of Campylobacter species and related organisms by matrix assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry

The identification of Campylobacter species and related organisms at the species level has always been difficult using phenotypic methods because of their low metabolic activity, whereas molecular methods are more reliable but time-consuming. In this study, 1007 different strains were identified using three different methods: conventional methods, molecular biology (real-time PCR and sequencing) and matrix assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry. Molecular methods were considered the gold standard. The accuracy of MALDI-TOF mass spectrometry reached 100% compared with the gold standard for all of the Campylobacter species, except Campylobacter jejuni (99.4%). The accuracy of conventional methods compared with the gold standard ranged from 0% to 100% depending on the species. However, MALDI-TOF mass spectrometry was not able to identify a mixture of two different species present in the same sample in four instances. Finally, MALDI-TOF mass spectrometry is highly recommended to identify Campylobacter spp. as only 0.4% discrepancy was found, whereas conventional methods led to 4.5% discrepancy.     

Comparative analysis of Campylobacter lari cytolethal distending toxin (CDT) effect on HeLa cells

We aimed to clarify if Campylobacter lari exerts a cytolethal distending toxin (CDT) effect on HeLa cells. Campylobacter cell lysates (CCLys) from C. jejuni 81–176 and urease‐positive thermophilic Campylobacter (UPTC) CF89‐12 and UPTC NCTC12893 isolates were shown to exert a CDT effect on HeLa cells with morphological changes examined by Giemsa staining and microscopy. However, Campylobacter lari JCM2530^T isolate showed no effect. In addition, Campylobacter cell culture supernatant wash gave low or absent toxic effects with both C. jejuni and C. lari organisms. When western blot analysis was carried out to clarify if there was a CDTB effect in the CCLys and soluble fractions from Campylobacter isolates, which had a CDT effect on HeLa cells or did not have any effect, anti‐recombinant CjCDTB antibodies identified an immunoreactively positive signal at around approximately 25 kDa on all the C. lari isolates examined, as well as the C. jejuni 81116 strain. Thus, all the Campylobacter isolates including those without any CDT effect were shown to express CDTB at the translational level. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)