Seasonal variation of Campylobacter types from human cases, veterinary cases, raw chicken, milk and water

Consortium of Lactobacillus crispatus 2029 and Ligilactobacillus salivarius 7247 Strains Shows In Vitro Bactericidal Effect on Campylobacter jejuni and, in Combination with Prebiotic, Protects Against Intestinal Barrier Dysfunction

Background/Objectives:Campylobacter jejuni (CJ) is the etiological agent of the world's most common intestinal infectious food-borne disease, ranging from mild symptoms to fatal outcomes. The development of innovative synbiotics that inhibit the adhesion and reproduction of multidrug-resistant (MDR) CJ in animals and humans, thereby preserving intestinal homeostasis, is relevant. We have created a synbiotic based on the consortium of Lactobacillus crispatus 2029 (LC2029), Ligilactobacillus salivarius 7247 (LS7247), and a mannan-rich prebiotic (Actigen®). The purpose of this work was to study the in vitro anti-adhesive and antagonistic activities of the created synbiotic against MDR CJ strains, along with its role in preventing intestinal barrier dysfunction, which disrupts intestinal homeostasis. Methods: A complex of microbiological, immunological, and molecular biological methods was used. The ability of the LC2029 and LS7247 consortium to promote intestinal homeostasis in vitro was assessed by the effectiveness of controlling CJ-induced TLR4 activation, secretion of pro-inflammatory cytokines, development of intestinal barrier dysfunction, and production of intestinal alkaline phosphatase (IAP). Results: All MDR CJ strains showed marked adhesion to human Caco-2, pig IPEC-J2, chicken CPCE, and bovine BPCE enterocytes. For the first time, we found that the prebiotic and cell-free culture supernatant (CFS) from the consortium of LC2029 and LS7247 strains exhibit an additive effect in inhibiting the adhesion of MDR strains of CJ to human and animal enterocytes. CFS from the LC2029 and LS7247 consortium increased the permeability of the outer and inner membranes of CJ cells, which led to extracellular leakage of ATP and provided access to the peptidoglycan of the pathogen for the peptidoglycan-degrading bacteriocins nisin and enterolysin A produced by LS7247. The LC2029 and LS7247 consortium showed a bactericidal effect on CJ strains. Co-cultivation of the consortium with CJ strains resulted in a decrease in the viability of the pathogen by 6 log. CFS from the LC2029 and LS7247 consortium prevented the growth of CJ-induced TLR4 mRNA expression in enterocytes. The LC2029 and LS7247 consortium inhibited a CJ-induced increase in IL-8 and TNF-α production in enterocytes, prevented CJ-induced intestinal barrier dysfunction, maintained the transepithelial electrical resistance of the enterocyte monolayers, and prevented an increase in intestinal paracellular permeability and zonulin secretion. CFS from the consortium stimulated IAP mRNA expression in enterocytes. The LC2029 and LS7247 consortium and the prebiotic Actigen represent a new synergistic synbiotic with anti-CJ properties that prevents intestinal barrier dysfunction and preserves intestinal homeostasis. Conclusions: These data highlight the potential of using a synergistic synbiotic as a preventive strategy for creating feed additives and functional nutrition products based on it to combat the prevalence of campylobacteriosis caused by MDR strains in animals and humans.

Assessing concordance between Campylobacter prevalence in broilers and human cases before and during the COVID-19 pandemic in Lower Saxony, Germany, considering fresh chicken meat consumption patterns

As the most common foodborne disease, number of campylobacteriosis decreased in Germany with the beginning of the COVID-19 pandemic in 2020. As the consumption of fresh chicken meat is a major risk factor for human infection, this study investigated the relationship between Campylobacter contamination levels on chicken carcasses and human cases in Lower Saxony, Germany and observed fresh chicken meat consumption patterns between 2018 and 2021 including the time of the COVID-19 pandemic. Campylobacter levels in broilers and human cases were classified based on the median and descriptively analysed per week using contingency tables. Before the COVID-19 pandemic (2018 and 2019), high Campylobacter contamination levels on neck samples and many human cases were more present, whereas with the beginning of the COVID-19 pandemic (2020 and 2021), low contamination levels on chicken carcasses and few human cases were more present. Lowest concordance between both parameters was shown in 2018 (Cohen's cappa coefficient: 0.37) and 2020 (0.38). The highest concordance was examined in 2021 (0.69). The private consumption of fresh chicken meat in Lower Saxony increased significantly with the beginning of the COVID-19 pandemic in 2020 by 63.9 tonnes compared to 2019 to an average of 453.5 tonnes per week. Public health measures and a reduced number of medical treatments have undoubtedly had an impact on less reported human cases during the COVID-19 pandemic. However, number of human cases remained at a low level in Germany in 2023 while chicken meat consumption increased. Thus, further risk assessments regarding the risk of campyloabcteriosis due to chicken meat consumption should include the country of origin, as the level of contamination of chicken carcasses varies between European countries.

Occurrence of antibiotic resistant C. jejuni and E. coli in wild birds, chickens, humans, and the environment in Malay villages, Kedah, Malaysia

Foodborne pathogens have become a major concern not only due to the diseases they cause, but also because of the rise of antibiotic resistant strains in human and animals. The purposes of this study were to determine the occurrence of Campylobacter jejuni and Escherichia coli and their antibiotic resistance profiles in wild birds, chickens, humans, and the environment in Malay villages in Malaysia. Three Malay villages in Kota Setar, Kedah were chosen. Three hundred nine (309) samples were collected in this study including wild birds (38), chickens (71), humans (47), and the environment (153). Subsequently, the C. jejuni and E coli isolates were tested against antibiotics using the disc diffusion method. Campylobacter jejuni was found positive in 17 (37.8%) flies and 8 (11.3%) chickens. Also, E. coli was found positive in 89.4% of human, 47.4% of bird, 44 62% of chicken and in 71.2% of the environmental samples. Ten antibiotics were used to determine the susceptibility of the isolates. Eighty four percent (84%) of C. jejuni and 100% of E. coli isolates were found to show resistance towards at least one antibiotic. The isolates showed high resistance to cefpodoxime and tetracycline.

Revisiting Campylobacter jejuni Virulence and Fitness Factors: Role in Sensing, Adapting, and Competing

Campylobacter jejuni is the leading cause of bacterial foodborne gastroenteritis world wide and represents a major public health concern. Over the past two decades, significant progress in functional genomics, proteomics, enzymatic-based virulence profiling (EBVP), and the cellular biology of C. jejuni have improved our basic understanding of this important pathogen. We review key advances in our understanding of the multitude of emerging virulence factors that influence the outcome of C. jejuni–mediated infections. We highlight, the spatial and temporal dynamics of factors that promote C. jejuni to sense, adapt and survive in multiple hosts. Finally, we propose cohesive research directions to obtain a comprehensive understanding of C. jejuni virulence mechanisms.

Survival and Control of Campylobacter in Poultry Production Environment

Campylobacter species are Gram-negative, motile, and non-spore-forming bacteria with a unique helical shape that changes to filamentous or coccoid as an adaptive response to environmental stresses. The relatively small genome (1.6 Mbp) of Campylobacter with unique cellular and molecular physiology is only understood to a limited extent. The overall strict requirement of this fastidious microorganism to be either isolated or cultivated in the laboratory settings make itself to appear as a weak survivor and/or an easy target to be inactivated in the surrounding environment of poultry farms, such as soil, water source, dust, surfaces and air. The survival of this obligate microaerobic bacterium from poultry farms to slaughterhouses and the final poultry products indicates that Campylobacter has several adaptive responses and/or environmental niches throughout the poultry production chain. Many of these adaptive responses remain puzzles. No single control method is yet known to fully address Campylobacter contamination in the poultry industry and new intervention strategies are required. The aim of this review article is to discuss the transmission, survival, and adaptation of Campylobacter species in the poultry production environments. Some approved and novel control methods against Campylobacter species throughout the poultry production chain will also be discussed.

Flagellin glycosylation with pseudaminic acid in Campylobacter and Helicobacter: prospects for development of novel therapeutics

Many pathogenic bacteria require flagella-mediated motility to colonise and persist in their hosts. Helicobacter pylori and Campylobacter jejuni are flagellated epsilonproteobacteria associated with several human pathologies, including gastritis, acute diarrhea, gastric carcinoma and neurological disorders. In both species, glycosylation of flagellin with an unusual sugar pseudaminic acid (Pse) plays a crucial role in the biosynthesis of functional flagella, and thereby in bacterial motility and pathogenesis. Pse is found only in pathogenic bacteria. Its biosynthesis via six consecutive enzymatic steps has been extensively studied in H. pylori and C. jejuni. This review highlights the importance of flagella glycosylation and details structural insights into the enzymes in the Pse pathway obtained via a combination of biochemical, crystallographic, and mutagenesis studies of the enzyme-substrate and -inhibitor complexes. It is anticipated that understanding the underlying structural and molecular basis of the catalytic mechanisms of the Pse-synthesising enzymes will pave the way for the development of novel antimicrobials.

Campylobacter jejuni Colonization in the Crow Gut Involves Many Deletions within the Cytolethal Distending Toxin Gene Cluster

Campylobacter spp. are major causes of gastroenteritis worldwide. The virulence potential of Campylobacter shed in crow feces obtained from a roost area in Bothell, Washington, was studied and compared with that from isolates from other parts of Washington and from a different crow species 7,000 miles away in Kolkata, India. Campylobacter organisms were isolated from 61% and 69% of the fecal samples obtained from Washington and Kolkata, respectively, and were confirmed to be C. jejuni The cytolethal distending toxin (CDT) gene cluster from these isolates revealed a truncated sequence of approximately 1,350 bp. Sequencing of the gene cluster revealed two types of mutations: a 668-bp deletion across cdtA and cdtB and a 51-bp deletion within cdtB Some strains had additional 20-bp deletions in cdtB In either case, a functional toxin is not expected; a functional toxin is produced by the expression of three tandem genes, cdtA, cdtB, and cdtC Reverse transcriptase PCR with total RNA extracted from the isolates showed no expression of cdtB A toxin assay performed with these isolates on HeLa cells failed to show cytotoxic effects on the cells. However, the isolates were able to colonize the chicken ceca for a period of at least 4 weeks, similar to that of a clinical isolate. Other virulence gene markers, flagellin A and CadF, were present in 100% of the isolates. Our study suggests that crows carry the bacterium C. jejuni but with a dysfunctional toxin protein that is expected to drastically reduce its potential to cause diarrhea.IMPORTANCE Campylobacters are a major cause of gastroenteritis in humans. Since outbreaks have most often been correlated with poultry or unpasteurized dairy products, contact with farm animals, or contaminated water, historically, the majority of the studies have been with campylobacter isolates from poultry, domestic animals, and human patients. However, the bacterium has a broad host range that includes birds. These reservoirs need to be investigated, because the identification of the source and a determination of the transmission routes for a pathogen are important for the development of evidence-based disease control programs. In this study, two species of the human-commensal crow, from two different geographical regions separated by 7,000 miles of land and water, have been examined for their ability to cause disease by shedding campylobacters. Our results show that the crow may not play a significant role in campylobacteriosis, because the campylobacter organisms they shed produce a nonfunctional toxin.

Campylobacter spp. Prevalence and Levels in Raw Milk: A Systematic Review and Meta-Analysis

Campylobacteriosis is the leading bacterial gastrointestinal disease internationally, contributing significantly to the enteric illness burden. Cases have been associated with the consumption of raw milk, a behavior that has garnered attention recently. Estimates of the prevalence and levels of Campylobacter spp. in raw milk are lacking, which hinders risk assessment attempts. This article is a systematic review and meta-analysis of reported prevalence and levels of zoonotic Campylobacter spp. in the raw milk of cows, goats, and sheep in Canada, the United States, Europe, Australia, and New Zealand. The relevant literature was reviewed, and trained reviewers examined the results for inclusion of articles in the meta-analysis. Relevant data (prevalence and/or level of Campylobacter in raw milk, country of origin, animal species, sample source, Campylobacter species identified, etc.) were extracted, and a meta-analysis was performed in Stata v. 12 (Metaprop command). The weighted mean prevalence of Campylobacter spp. in raw milk samples was 1.18%. Subgroup analyses were conducted to examine how prevalence varied by study characteristics, with the highest prevalence values in studies from the United Kingdom (by country, 6.4%), about cows (by animal species, 1.3%), and including samples taken from inline filters (by sample source, 1.75%) and in studies that included species that are not pathogenic to humans (by Campylobacter species, 1.14%). Two articles each included a single Campylobacter level, 0.16 ± 0.3 and approximately 0.047 most probable number per ml. Despite a relatively low prevalence, consumption of raw milk is inherently risky because no treatment has been used to inactivate pathogens. This potential risk further supports maintaining regulations to limit the sales of raw milk.

Microbial transport into groundwater from irrigation: Comparison of two irrigation practices in New Zealand

Rising demand on food is leading to an increase in irrigation worldwide to improve productivity. Irrigation, for pastoral agriculture (beef, dairy and sheep), is the largest consumptive use of water in New Zealand. There is a potential risk of leaching of microbial contaminants from faecal matter through the vadose zone into groundwater. Management of irrigation is vital for protection of groundwater from these microbial contaminants and maintain efficient irrigation practices. Our research investigated flood and spray irrigation, two practices common in New Zealand. The aim was to identify the risk of microbial transport and mitigation practices to reduce or eliminate the risk of microbial transport into groundwater. Cowpats were placed on lysimeters over a typical New Zealand soil (Lismore silt loam) and vadose zone and the leachate collected after irrigation events. Samples of both cowpats and leachate were analysed for the microbial indicator Escherichia coli and pathogen Campylobacter species. A key driver to the microbial transport derived from the model applied was the volume of leachate collected: doubling the leachate volume more than doubled the total recovery of E. coli. The persistence of E. coli in the cowpats during the experiment is an important factor as well as the initial environmental conditions, which were more favourable for survival and growth of E. coli during the spray irrigation compared with the flood irrigation. The results also suggest a reservoir of E. coli surviving in the soil. Although the same was potentially true for Campylobacter, little difference in the transport rates between irrigation practices could be seen due to the poor survival of Campylobacter during the experiment. Effective irrigation practices include monitoring the irrigation rates to minimise leachate production, delaying irrigation until 14days post-cowpat deposition and only irrigating when risk of transport to the groundwater is minimal.

AIM

To compare the risk of microbial contamination of groundwater from cowpats using two irrigation practices onto pasture.

Regulation of oxidative stress resistance in Campylobacter jejuni, a microaerophilic foodborne pathogen

Campylobacter jejuni is one of the leading bacterial causes of human gastroenteritis. Due to the increasing rates of human campylobacteriosis, C. jejuni is considered as a serious public health concern worldwide. C. jejuni is a microaerophilic, fastidious bacterium. C. jejuni must overcome a wide range of stress conditions during foodborne transmission to humans, such as food preservation and processing conditions, and even in infection of the gastrointestinal tracts of humans. Particularly, this microaerophilic foodborne pathogen must survive in the atmospheric conditions prior to the initiation of infection. C. jejuni possesses unique regulatory mechanisms for oxidative stress resistance. Lacking OxyR and SoxRS that are highly conserved in other Gram-negative foodborne pathogens, C. jejuni modulates the expression of genes involved in oxidative stress resistance mainly via the peroxide resistance regulator and Campylobacter oxidative stress regulator. Based on recent findings of ours and others, in this review, we described how C. jejuni regulates the expression of oxidative stress defense.

Global Distribution of Campylobacter jejuni Penner Serotypes: A Systematic Review

Penner serotyping has been the principal method for differentiating Campylobacter isolates since its inception. Campylobacter capsule polysaccharide (CPS), the principal serodeterminant on which Penner serotyping is based, is presently of interest as a vaccine component. To determine the required valency of an effective CPS-based vaccine, a comprehensive understanding of CPS distribution is needed. Because of the association between Penner serotype and CPS, we conducted a systematic review to estimate the frequency and distribution of Penner serotypes associated with cases of Campylobacteriosis. In total, more than 21,000 sporadic cases of C. jejuni cases were identified for inclusion. While regional variation exists, distribution estimates indicate that eight serotypes accounted for more than half of all sporadic diarrheal cases globally and three serotypes (HS4 complex, HS2, and HS1/44) were dominant inter-regionally as well as globally. Furthermore, a total of 17 different serotypes reached a representation of 2% or greater in at least one of the five regions sampled. While this review is an important first step in defining CPS distribution, these results make it clear that significant gaps remain in our knowledge. Eliminating these gaps will be critical to future vaccine development efforts.

Circulating Methylated XAF1 DNA Indicates Poor Prognosis for Gastric Cancer

BACKGROUND

Methylated DNA in fluids may be a suitable biomarker for cancer patients. XAF1 has been shown to be frequently down-regulated in human gastric cancer (GC). Here, we investigated if XAF1 methylation in GC could be a useful biomarker.

METHODS

Real-time RT-PCR was used to detect XAF1 mRNA expression; immunohistochemistry and western blot were used to examine XAF1 protein expression in GC tissues (n = 202) and their corresponding para-cancerous histological normal tissues (PCHNTs). Real-time methylation specific-PCR was used to investigate XAF1 promoter methylation in the same panel of GC tissues, their PCHNTs and sera.

RESULTS

We confirmed frequent XAF1 down-regulation in both mRNA and protein levels in GC tissues as compared to normal controls and PCHNTs. XAF1 hypermethylation was evidenced in 83.2% (168/202) of GC tissues and 27.2% (55/202) of PCHNTs, while no methylation was detected in the 88 normal controls. The methylation level in GC tissues was significantly higher than that in PCHNTs (p<0.05). The hypermethylation of XAF1 significantly correlated with the down-regulation of XAF1 in GC tissues in both mRNA and protein levels (p<0.001 each). Moreover, we detected high frequency of XAF1 methylation (69.8%, 141 out of 202) in the sera DNAs from the same patients, while the sera DNAs from 88 non-tumor controls were negative for XAF1 methylation. The XAF1 methylation in both GC tissues and in the sera could be a good biomarker for diagnosis of GC (AUC = 0.85 for tissue and AUC = 0.91 for sera) and significantly correlated with poorer prognosis (p<0.001). In addition, after-surgery negative-to-positive transition of XAF1 methylation in sera strongly associated with tumor recurrence.

CONCLUSIONS

1) Dysfunction of XAF1 is frequent and is regulated through XAF1 promoter hypermethylation; 2) Detection of circulating methylated XAF1 DNAs in the serum may be a useful biomarker in diagnosis, evaluating patient's outcome (prognosis and recurrence) for GC patients.

Application of molecular epidemiology to understanding campylobacteriosis in the Canterbury region of New Zealand

Pulsed-field gel electrophoresis genotypes of Campylobacter isolates from 603 human patients were compared with 485 isolates from retail offal (primarily chicken and lamb) to identify temporal clusters and possible sources of campylobacteriosis. Detailed epidemiological information was collected from 364 of the patients, and when combined with genotyping data allowed a putative transmission pathway of campylobacteriosis to be assigned for 88% of patients. The sources of infection were 47% food, 28% direct animal contact, 7% overseas travel, 4% person-to-person transmission and 3% water-related. A significant summer increase in campylobacteriosis cases was primarily attributed to an increase in food-related cases. Genotyping of isolates was essential for identifying the likely cause of infection for individuals. However, a more rapid and cheaper typing tool for Campylobacter is needed, which if applied to human and animal isolates on a routine basis could advance greatly our understanding of the ongoing problem of Campylobacter infection in New Zealand.

Campylobacter epidemiology: a descriptive study reviewing 1 million cases in England and Wales between 1989 and 2011

OBJECTIVES

To review Campylobacter cases in England and Wales over 2 decades and examine the main factors/mechanisms driving the changing epidemiology.

DESIGN

A descriptive study of Campylobacter patients between 1989 and 2011. Cases over 3 years were linked anonymously to postcode, population density, deprivation indices and census data. Cases over 5 years were anonymously linked to local weather exposure estimates.

SETTING

Patients were from general practice, hospital and environmental health investigations through primary diagnostic laboratories across England and Wales.

PARTICIPANTS

There were 1 109 406 cases.

OUTCOME MEASURES

Description of changes in Campylobacter epidemiology over 23 years and how the main drivers may influence these.

RESULTS

There was an increase in Campylobacter cases over the past 23 years, with the largest increase in people over 50 years. Changes in the underlying population have contributed to this, including the impacts of population increases after World War I, World War II and the 'baby boom' of the 1960s. A recent increase in risk or ascertainment within this population has caused an increase in cases in all age groups from 2004 to 2011. The seasonal increase in cases between weeks 18 (Early May) and 22 (Early June) was consistent across ages, years and regions and was most marked in children and in more rural regions. Campylobacter prevalence by week in each region correlated with temperature 2 weeks before. There were higher prevalences in areas with a low population density, low deprivation and lower percentage of people of ethnic origin. Data from sero-phage and multilocus sequence typing show a few common types and many uncommon types.

CONCLUSIONS

The drivers/mechanisms influencing seasonality, age distribution, population density, socioeconomic and long-term differences are diverse and their relative contributions remain to be established. Surveillance and typing provide insights into Campylobacter epidemiology and sources of infection, providing a sound basis for targeted interventions.

Survival of Campylobacter jejuni on beef and pork under vacuum packaged and retail storage conditions: examination of the role of natural meat microflora on C. jejuni survival

The ability of Campylobacter jejuni ATCC 11168 to survive on beef and pork stored under chilled, vacuum packaged and retail display conditions were examined. In addition, the effect of natural microflora on commercial beef and pork on the survival of C. jejuni under these storage conditions was examined. When sterile cores of beef and pork were inoculated with ∼ 10(5) to 10(6) cfu cm(-2)C. jejuni, and were stored under aerobic or vacuum packaged conditions at -1.5 or 4 °C, its numbers dropped significantly and C. jejuni could not be enumerated by direct plating after 21 d of the 6 wks study. In contrast, survival of C. jejuni on commercial vacuum packaged beef and pork was significantly enhanced, resulting in only 1 log cfu cm(-2) reduction at the end of 6 wks. During 7 d of display in a retail case, numbers of C. jejuni dropped quickly, but could be enumerated by direct plating even after the 7 d. The presence of high numbers of inoculated C. jejuni on beef and pork had no significant effect on the natural microflora numbers compared to uninoculated controls when the meat was stored either in vacuum or in a retail display case. These results show that natural microflora on vacuum packaged meat afford enhanced survival of C. jejuni present on the surfaces of both beef and pork when stored at refrigeration temperatures. Hence, strict hygienic practices or the implementation of decontamination technologies are recommended to ensure safety of meat with respect to this pathogen.

Prevalence, antibiograms, and transferable tet(O) plasmid of Campylobacter jejuni and Campylobacter coli isolated from raw chicken, pork, and human clinical cases in Korea

The antibiotic resistance patterns and prevalence of the transferable tet(O) plasmid were investigated in Campylobacter jejuni and Campylobacter coli isolates from raw chicken, pork, and humans with clinical campylobacteriosis. A total of 180 C. jejuni and C. coli isolates were identified, and the prevalence rates of C. jejuni and C. coli in raw chicken samples were 83% (83 of 100) and 73% (73 of 100), respectively. Twelve percent (6 of 50) and 10% (5 of 50) of pork samples were contaminated with C. jejuni and C. coli, respectively. Disk diffusion susceptibility testing revealed that the most frequently detected resistance was to tetracycline (92.2%), followed by nalidixic acid (75.6%), ciprofloxacin (65.0%), azithromycin (41.5%), ampicillin (33.3%), and streptomycin (26.1%). Of the C. jejuni and C. coli isolates, 65.7% (n=109) contained plasmids carrying the tet(O) gene. Six C. jejuni isolates and two C. coli isolates with high-level resistance to tetracycline (MIC=256 microg/ml) harbored the tet(O) plasmid, which is transferable to other C. jejuni and C. coli isolates. These results demonstrate the presence of an interspecies transferable plasmid containing the tet(O) gene and a high prevalence of antibiotic resistance in Korean Campylobacter isolates and provide an understanding of the antibiotic resistance distribution among Campylobacter species in Korea.

Novel clonal complexes with an unknown animal reservoir dominate Campylobacter jejuni isolates from river water in New Zealand

Campylobacter jejuni is widely distributed in the environment, and river water has been shown to carry high levels of the organism. In this study, 244 C. jejuni isolates from three river catchment areas in New Zealand were characterized using multilocus sequence typing. Forty-nine of the 88 sequence types identified were new. The most common sequence types identified were ST-2381 (30 isolates), ST-45 (25 isolates), and ST-1225 (23 isolates). The majority of the sequence types identified in the river water could be attributed to wild bird fecal contamination. Two novel clonal complexes (CC) were identified, namely, CC ST-2381 (11 sequence types, 46 isolates) and CC ST-3640 (6 sequence types, 12 isolates), in which all of the sequence types were new. CC ST-2381 was the largest complex identified among the isolates and was present in two of the three rivers. None of the sequence types associated with the novel complexes has been identified among human isolates. The ST-2381 complex is not related to complexes associated with cattle, sheep, or poultry. The source of the novel complexes has yet to be identified.

Environmental determinants of campylobacteriosis risk in Philadelphia from 1994 to 2007

Campylobacter species infections are a common cause of acute gastroenteritis, and may uncommonly be complicated by renal, neurological, and rheumatologic sequelae. Although excess summertime campylobacteriosis has been observed, environmental mechanisms driving disease seasonality are poorly understood. We sought to evaluate the relationship between environmental factors and campylobacteriosis risk in a major North American metropolitan area. We evaluated 1532 cases of campylobacteriosis reported in Philadelphia between 1994 and 2007. We constructed Poisson regression models with oscillatory smoothers, and also used case-crossover design, to evaluate the associations between environmental exposures and disease risk on weekly and daily time scales. Both methods control for confounding by seasonally oscillating environmental factors. Incidence was greatest in June and July, with annual periodicity. Weekly incidence was associated with increasing relative humidity, (incidence rate ratio (IRR) per % 1.017, 95% CI 1.008-1.025), temperature (IRR per degrees C 1.041, 95% CI 1.011-1.072), and decreasing Delaware River temperature during the same week (IRR per degrees C 0.922, 95% CI 0.883-0.962), and at 4-week lags (IRR per degrees C 0.953, 95% CI 0.919-0.990). No acute associations were identified in case-crossover analyses. Our findings affirm the summertime seasonality of campylobacteriosis in Philadelphia, and the link between warm, humid weather and disease risk. However, the link between low river temperatures and enhanced campylobacteriosis risk in humans described here is novel, consistent with known links between watershed temperature and Campylobacter survival, and implicates local watersheds as epidemiologically important reservoirs for foodborne pathogens.

The transmission of thermotolerant Campylobacter spp. to people living or working on dairy farms in New Zealand

New Zealand has one of the highest rates of campylobacteriosis in the developed world with an incidence rate of 383.5 cases per 100,000 in 2006. Dairy farming has been suggested as a potential source of campylobacteriosis. To explore this connection, seven farm investigations were undertaken at dairy farms on which a campylobacteriosis case had been notified. Campylobacter spp. were isolated from a range of sources on the farm (including 66% of bovine faecal samples) and genotypes compared with that of the clinical isolate of the index case. In depth, epidemiological questionnaires were also administered to determine exposure risks from a wide range of possible sources. Contact with dairy cow faeces was the most likely source of infection in four of the seven cases investigated, and occurred exclusively in new farm workers and children. In one of the cases investigated, infection was likely to have been acquired from non-dairy related sources, and in two cases the source could not be determined. The relative risk of dairy farm worker being notified with campylobacteriosis was estimated to be 1.88 (95% confidence interval=1.6-2.2).

Incidence and ecology of Campylobacter jejuni and coli in animals

Since its initial emergence in the 1970s, Campylobacter has become one of the most common causative agents of bacterial foodborne illness. Campylobacter species readily colonize the gastrointestinal tracts of domestic, feral and wild animals and while they rarely cause clinical disease in food animals, they can produce severe acute gastroenteritis in humans. Prevalence of Campylobacter in food animals can exceed 80% thus challenging processors to employ post-harvest pathogen reduction strategies. Reduction of pathogens before arrival to the abattoir is also of interest because the implementation of pre-harvest interventions may compliment existing post-harvest control techniques to further diminish possible retail sources of infection. Such multiple hurdle approaches that simultaneously utilize pre- and post-harvest control techniques are expected to be the most effective approach for decreasing human illness associated with foodborne pathogens.

Comparison of Campylobacter jejuni genotypes from dairy cattle and human sources from the Matamata-Piako District of New Zealand

AIMS

To identify the prevalence and types of Campylobacter jejuni carried by dairy cattle and the extent of overlap of these types with those causing disease in humans.

METHODS AND RESULTS

Faecal samples from 410 dairy cattle were collected from 36 farms in the Matamata-Piako district in New Zealand. Campylobacter jejuni was isolated on all 36 farms, with a prevalence of 51% (95% CI 45-57) in dairy cattle and 65% (95% CI 58-72) in calves. Eighty-nine of these isolates were typed using Penner serotyping and pulsed field gel electrophoresis and were compared with 58 human C. jejuni isolates from people resident within this study area.

CONCLUSIONS

Campylobacter jejuni were found in the faeces of over half of the dairy cows and calves examined. Twenty-one per cent of the bovine isolates and 43% of the human isolates formed indistinguishable clusters of at least one bovine and one human isolate.

SIGNIFICANCE AND IMPACT OF THE STUDY

While a direct link between bovine isolates and human cases was not demonstrated, the finding of indistinguishable genotypes among C. jejuni isolates from bovine and human sources confirms that dairy cows and calves are a potential source of human campylobacteriosis. Barriers to separate bovine faecal material from the general public are therefore important public health measures.

Molecular epidemiology of Campylobacter jejuni populations in dairy cattle, wildlife, and the environment in a farmland area

We describe a cross-sectional study of the molecular epidemiology of Campylobacter jejuni in a dairy farmland environment, with the aim of elucidating the dynamics of horizontal transmission of C. jejuni genotypes among sources in the area. A collection of 327 C. jejuni isolates from cattle, wildlife, and environmental sources in a 100-km(2) area of farmland in northwest England was characterized by multilocus sequence typing. A total of 91 sequence types and 18 clonal complexes were identified. Clonal complexes ST-21, ST-45, and ST-61, which have been frequently associated with human disease, were the most commonly recovered genotypes in this study. In addition, widely distributed genotypes as well as potentially host-associated genotypes have been identified, which suggests that both restricted and interconnecting pathways of transmission may be operating in the dairy farmland environment. In particular, the ST-61 complex and the ST-21 complex were significantly associated with cattle. In contrast, complex strains ST-45, ST-952, and ST-677 were isolated predominantly from wild birds, wild rabbits, and environmental water. A considerable number of novel sequence types have also been identified, which were unassigned to existing clonal complexes and were frequently isolated from wildlife and environmental sources. The segregated distribution of genotypes among samples from different sources suggests that their transmission to humans is perhaps via independent routes. Insight into the dynamics and interactions of C. jejuni populations between important animal reservoirs and their surrounding environment would improve the identification of sources of Campylobacter infection and the design of control strategies.

Wide geographical distribution of internationally rare Campylobacter clones within New Zealand

During the southern hemisphere winter of 2006 New Zealand experienced a significant increase in the number of reported cases of Campylobacter infection. In total, 112 Campylobacter isolates from eight district health boards (DHBs) located across New Zealand were submitted for PFGE, MLST and Penner serotyping analysis. Distinct clusters of Campylobacter isolates were identified, several of which were composed of isolates from up to five different DHBs located on both the North and South islands of New Zealand. One sequence type, ST-474, was identified in 32 of the 112 isolates and may represent an endemic sequence type present in New Zealand. The spatial pattern of genotypes, combined with the generalized increase in notifications throughout the country is consistent with a common source epidemic, most likely from a source contaminated with the dominant sequence types ST-474 and ST-190 and may also represent widely distributed stable clones present in New Zealand.

Survival of indicator and pathogenic bacteria in bovine feces on pasture

The survival of enteric bacteria was measured in bovine feces on pasture. In each season, 11 cow pats were prepared from a mixture of fresh dairy cattle feces and sampled for up to 150 days. Four pats were analyzed for Escherichia coli, fecal streptococci, and enterococci, and four inoculated pats were analyzed for Campylobacter jejuni and Salmonella enterica. Two pats were placed on drainage collectors, and another pat was fitted with a temperature probe. In the first 1 to 3 weeks, there were increases (up to 1.5 orders of magnitude) in the counts of enterococci (in four seasons), E. coli (three seasons), fecal streptococci (three seasons), and S. enterica (two seasons), but there was no increase in the counts of C. jejuni. Thereafter, the counts decreased, giving an average ranking of the times necessary for 90% inactivation of C. jejuni (6.2 days from deposition) < fecal streptococci (35 days) < S. enterica (38 days) < E. coli (48 days) < enterococci (56 days). The pat temperature probably influenced bacterial growth, but the pattern of increases and decreases was primarily determined by desiccation; growth occurred when the water content was greater than 80%, but at a water content of 70 to 75% counts decreased. E. coli and enterococcus regrowth appeared to result from pat rehydration. Of 20 monthly leaching losses of E. coli, 16 were <10% of the total counts in the pat, and 12 were <1%. Drainage losses of C. jejuni (generally <1%) were detected for only 1 to 2 months. Although enterococci exhibited the best survival rate, higher final counts suggested that E. coli is the more practical indicator of bovine fecal pollution.

Multilocus sequence typing of Campylobacter jejuni isolates from New South Wales, Australia

AIMS

Multilocus sequence typing (MLST) was used to examine the diversity and population structure of Campylobacter jejuni isolates associated with sporadic cases of gastroenteritis in Australia, and to compare these isolates with those from elsewhere.

METHODS AND RESULTS

A total of 153 Camp. jejuni isolates were genotyped. Forty sequence types (STs) were found, 19 of which were previously undescribed and 21 identified in other countries. The 19 newly described STs accounted for 43% of isolates, 16 of which were assigned to known clonal complexes. Eighty-eight percent of isolates were assigned to a total of 15 clonal complexes. Of these, four clonal complexes accounted for 60% of isolates. Three STs accounted for nearly 40% of all isolates and appeared to be endemic, while 21 STs were represented by more than one isolate. Seven infections were acquired during international travel, and the associated isolates all had different STs, three of which were exclusive to the travel-acquired cases. Comparison of serotypes among isolates from clonal complexes revealed further diversity. Eight serotypes were identified among isolates from more than one clonal complex, while isolates from six clonal complexes displayed serotypes not previously associated with those clonal complexes.

CONCLUSIONS

Multilocus sequence typing is a useful tool for the discrimination of subtypes and examination of the population structure of Camp. jejuni associated with sporadic infections.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study highlights the genotypic diversity of Camp. jejuni in Australia, demonstrating that STs causing disease have both a global and a local distribution evident from the typing of domestically and internationally acquired Camp. jejuni isolates.

Salmonella in uncooked retail meats in New Zealand

A national quantitative survey of Salmonella in five types of uncooked retail meats in New Zealand was undertaken from August 2003 to May 2005 to establish baseline proportionality data. The overall prevalence of Salmonella in 1,108 meat samples was 1.1% (95% confidence interval, 0.6 to 1.9). Low prevalences of Salmonella in each meat type were observed, with 3% (1.2 to 6.1) in chicken, 1.3% (0.3 to 3.8) in lamb and mutton, 0.5% (0 to 3.0) in unweaned veal, 0.4% (0 to 2.4) in beef, and 0% (0 to 1.6) in pork. The Salmonella serotypes isolated were Salmonella Infantis from beef; Salmonella Typhimurium PT1 from unweaned veal and chicken; Salmonella sp. 6,7:k:-, Salmonella Enteritidis PT9a, Salmonella sp. 4,5,12:-:-, Salmonella sp. 4,12:-:-, and Salmonella Typhimurium PT160 from chicken; and Salmonella sp. 4:-:2 and Salmonella Brandenburg from lamb. Four of the isolates from chicken, Salmonella sp. 4,5,12:-:- (two isolates), Salmonella sp. 4,12:-:-, and Salmonella Typhimurium PT1, were very similar phenotypically and serologically to the attenuated Salmonella vaccine strain used in MeganVacl for poultry. One lamb sample yielded a count of Salmonella Brandenburg of 4.24 most probable number (MPN)/g, while all other positive samples were <1.0 MPN/g. The results provide baseline proportionality data for Salmonella in retail uncooked meats that will contribute invaluably toward future risk assessment in light of other information, such as consumption data that can be used for risk characterization.

Prevalence and numbers of coliphages and Campylobacter jejuni bacteriophages in New Zealand foods

Vegetable samples were tested for the presence of coliphages. None of the 55 samples contained these phages at concentrations greater than 10 g(-1) (the limit of detection). Spiking and recovery experiments indicated that the method was efficient at detecting coliphage T4 added to the food, and so it was concluded that phage titres were not being falsely underestimated. In addition 51 samples of chicken skin from retail portions were tested for the presence and numbers of coliphages and for presence only of Campylobacter jejuni phages. Coliphages were isolated from 46 samples (90.2% positive), at up to 2570 PFU 10 g sample(-1) but no C. jejuni phages were isolated. Several other methods were used to isolate C. jejuni phages from retail chicken but none was successful. However, when pooled whole chicken rinses from 39 flocks were tested for the presence of C. jejuni phages, 11 (28.2%) of the flocks were positive. It is possible that phages present on birds at the start of processing were either inactivated or simply diluted out during spin chilling. These data add to the body of information indicating that phages can readily be isolated from certain foods and indicate that consumers are exposed to them on a regular basis.

Prevalence, numbers, and subtypes of Campylobacter jejuni and Campylobacter coli in uncooked retail meat samples

A national quantitative survey of Campylobacter jejuni and Campylobacter coli in 1,011 uncooked retail meat samples (beef, unweaned veal, chicken, lamb and mutton, and pork) was undertaken from August 2003 to June 2004 to establish baseline proportionality data. The presence, number, and type of Campylobacter present in each sample was assessed. Prevalences of C. jejuni and C. coli were 89.1% in chicken, 9.1% in pork, 6.9% in lamb and mutton, 3.5% in beef, and 10% in unweaned veal. C. jejuni was identified in the majority of positive samples (246 of 259). In chicken samples positive for C. jejuni, 40.2% had counts of <0.3 most probable number (MPN)/g, 50.5% had 0.3 to 10.0 MPN/g, 8.8% had 10.1 to 50.0 MPN/g, and 0.5% had 110 MPN/g. In other meats (49 samples), Campylobacter counts were < or = 0.3 MPN/g, except for one unweaned veal sample at > 10.9 MPN/g. Penner serotyping and SmaI macrorestriction genotyping using pulsed-field gel electrophoresis with 247 isolates revealed 17 Penner serotypes and 56 electrophoresis profiles. Seven Penner serotypes (HS1 complex, 2, 4 complex, 6, 11, 27, and 42) were represented by 10 or more isolates from chicken. When data from both typing methods were combined, 62 sero-genotypes were generated. In a comparison of these sero-genotypes with historical data for isolates from human cases, 71% of the beef isolates, 50% of the lamb and mutton isolates, 50% of the pork isolates, 41% of the chicken isolates, and 25% of the unweaned veal isolates were common to both sources. These results provide baseline proportionality profiles of Campylobacter in these five meats and will facilitate exposure assessment in combination with other information such as consumption data and subsequent quantitative risk assessment.

PFGE genotyping and antimicrobial susceptibility of Campylobacter in retail poultry meat in Estonia

In the present study, the Campylobacter isolates from retail poultry meat in Estonia were sero- and genotyped, and the antimicrobial susceptibility was determined. Forty-eight chicken (36 Estonian, 12 imported) and 22 turkey (imported) Campylobacter isolates from 580 raw broiler chicken (396 Estonian, 184 imported) and 30 turkey (imported) meat samples were studied. Of the isolates, 64 were C. jejuni, 4 C. coli, and 2 Campylobacter spp. Penner serotyping of 54 C. jejuni isolates revealed 11 different serotypes, and 22% of the isolates were nontypeable by the commercial antisera. The most common serotypes O:1,44; O:21, and O:55 accounted for 28%, 13%, and 13% of the isolates, respectively. Differences in serotype distribution were seen for chicken and turkey isolates. Genotypic characterization of all Campylobacter isolates (n=70) was performed by pulsed-field gel electrophoresis (PFGE). SmaI and KpnI yielded 29 and 34 PFGE types, respectively, revealing high diversity among isolates. The serotype distribution did not show an association with the origin of the sample, but the majority of the isolates sharing a similar PFGE genotype originated from one country. High levels of resistance to ciprofloxacin (66%), nalidixic acid (66%), tetracycline (44%), ampicillin (34%), and erythromycin (14%) were detected among the 70 Campylobacter isolates. The simultaneous resistance to two or three antimicrobial agents occurred in 60% of the isolates. The Campylobacter isolates from turkey meat had higher resistance to ampicillin, ciprofloxacin, nalidixic acid, and tetracycline than those from chicken meat. None of the chicken isolates were resistant to gentamicin, and no turkey isolates to erythromycin or gentamicin.

Campylobacter in chicken livers and their destruction by pan frying

AIM

To enumerate Campylobacter spp. on the external surface and internal portions of chicken livers, and to assess the cooking required to inactivate naturally present cells.

METHODS AND RESULTS

Of 30 livers tested all yielded Campylobacter spp. on their surfaces and 90% were found to contain the organism in internal tissue. Four (13%) livers contained >10(4) MPN campylobacters, and an additional seven (23%) contained >10(3) MPN campylobacters per liver. The internal temperature of pan-fried livers under the conditions used reached a maximum of 70-80 degrees C, and maintaining this temperature for 2-3 min was necessary to inactivate naturally occurring Campylobacter spp. All isolates identified were either C. jejuni or C. coli.

CONCLUSIONS

Chicken livers represent a potential source of human campylobacteriosis as they contained >10(4) MPN per liver in 13% of the samples tested. Pan-frying can produce an acceptable product that is safe to eat. SIGNIFICANCE AND IMPACT OF THIS STUDY: The data provided can be used in exposure assessments of Campylobacter in poultry products in terms of both quantitative data and assessing pan-frying and its ability to destroy campylobacters.

Comparison of Campylobacter jejuni PFGE and Penner subtypes in human infections and in water samples from the Taieri River catchment of New Zealand

AIMS

To determine the degree of overlap in strain types of Campylobacter jejuni isolated from clinical cases and water samples from the Taieri catchment in the South Island of New Zealand.

METHODS AND RESULTS

Thermophilic Campylobacter were collected from human cases of infection, the main stem of the Taieri River and streams within distinct land-use types over a 1-year period. Campylobacter jejuni (187 isolates) and Campylobacter lari (four isolates) were identified using a multiplex polymerase chain reaction protocol. Isolates were typed by the Penner method and pulsed-field gel electrophoresis (PFGE) utilizing two restriction endonucleases. Several serotypes and PFGE types occurred in both water samples and clinical cases when the restriction profiles for each enzyme were considered separately. However, when PFGE profiles and serotyping were combined, there was no overlap between Camp. jejuni types from water and clinical cases.

CONCLUSIONS

The results of this study indicate that recreational water in the Taieri catchment is not a major source of campylobacteriosis in the Dunedin area.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study suggests the risk of acquiring campylobacteriosis from surface waters in the Taieri catchment is considerably lower than previously predicted and highlights the necessity of using two endonucleases in PFGE typing.

Is the major increase in notified campylobacteriosis in New Zealand real?

Notifications of campylobacteriosis by New Zealand medical practitioners have increased steadily in the last two decades. To determine if this increase is real, as opposed to a surveillance artefact, we examined both available notification (1980-2003) and hospitalization data (1995-2003). The similarity in the temporal pattern of increasing hospitalizations for campylobacteriosis, with that of notifications, is suggestive that this increase is indeed real. Although some risk factors for this disease have been identified (e.g. uncooked poultry consumption) it is unclear what the likely causes of the increasing rates are. The overall disease burden is also high compared with other developed countries (an annual notification rate of 396 cases per 100000 population in 2003), with highest rates in children aged 1-4 years, males, Europeans, and those living in urban areas. Given the large disease burden, further research and intervention studies should be public health priorities in this country.

Risk factors for Campylobacter spp. colonization in broiler flocks in Iceland

We sampled 1,091 Icelandic broiler flocks at slaughter from May 2001 to December 2003 to determine the prevalence of, and investigate risk factors for the presence of, Campylobacter spp. at the flock level. Approximately 15% of the flocks were positive for Campylobacter spp.; most (95%) of the infected flocks being raised during the months of April-September. Based on the data from the latter months, and using multivariable logistic regression with random effects for herd, we found that the odds of a flock being positive for Campylobacter spp. increased with age and flock size. Additionally, vertical ventilation systems were strongly associated with positive flocks (OR=5.3). After controlling for these variables, we found no evidence of an effect of: year; company; Campylobacter being carried over from one flock to the next; time interval between flocks; using (at the hatcheries) eggs laid on the floor; density of bird housing, or the number of catch lots a flock was divided into for slaughtering purposes on the risk of a Campylobacter-positive flock.

Amplified fragment length polymorphism, serotyping, and quinolone resistance of Campylobacter jejuni and Campylobacter coli strains from chicken-related samples and humans in Taiwan

The high-resolution genotyping method of amplified fragment length polymorphism (AFLP) analysis was used to study the genetic relationships between Campylobacter jejuni isolates from chicken-related samples (n = 32) and humans (n = 27) as well as between Campylobacter coli isolates from chicken-related samples (n = 27) and humans (n = 5). These isolates were collected between 1994 and 2003 in Taiwan. All C. jejuni and C. coli isolates showed highly heterogeneous fingerprints. C. jejuni isolates were separated in two distinct genetic clusters (A and B) at 40% genetic similarity and 42 different AFLP types at 90% similarity. However, three clusters at 40% genetic similarity and 33 different AFLP types at 90% similarity were observed in C. coli isolates. These results showed that AFLP analysis could be used to identify individual isolates of two Campylobacter species. Among C. jejuni isolates, the predominant AFLP type 1 was observed in five (7.9%) isolates, and types 5 and 12 in four (6.3%) isolates each. Cluster B consisted of 10 isolates, while the majority of isolates (n = 53) belonged to cluster A. In some AFLP types (1, 5, 12, 14 and 31), AFLP fingerprints of chicken-related isolates were closely related genetically to those of isolates from humans with gastroenteritis. The predominant serotypes in C. jejuni isolates were B:2 and Y:37. All isolates belonging to serotype O:19 grouped into one single AFLP type. Some chicken samples yielded multiple isolates of Campylobacter harboring simultaneously quinolone-resistant and quinolone-sensitive isolates attributed to the same species, or harboring C. jejuni and C. coli that have the characteristics of quinolone resistance.

Most Campylobacter subtypes from sporadic infections can be found in retail poultry products and food animals

The subtypes of Campylobacter isolates from human infections in two Danish counties were compared to isolates from retail food samples and faecal samples from chickens, pigs and cattle. During a 1-year period, 1285 Campylobacter isolates from these sources were typed by two methods: 'Penner' heat-stable serotyping and automated ribotyping (RiboPrinting). C. jejuni was the dominating species, but C. coli was more prevalent among food and chicken isolates (16%) compared to human isolates (4%). In total, 356 different combined sero-ribotypes (subtypes) were found. A large subtype overlap was seen between human isolates and isolates from food (66%), chickens (59%) and cattle (83%). This was verified by PFGE typing of 212 isolates representing selected subtypes. All frequent (n>3) subtypes found in food were also present in humans. Sixty-one per cent of the isolates from domestically acquired infections had subtypes that were also found in food as opposed to 31% of travel-associated infections. The results showed differences in the various Campylobacter populations, e.g. the Danish population as reflected in the domestically acquired infections and the Danish-produced food was more uniform than the isolates originating from outside the country. The study shows that most C. jejuni subtypes found in poultry food samples, broiler chickens, and cattle were represented in the domestically acquired cases, indicating that C. jejuni from these reservoirs are likely sources of human infections in Denmark.

The occurrence of Campylobacter subtypes in environmental reservoirs and potential transmission routes

AIM

To identify potential reservoirs and transmission routes of human pathogenic Campylobacter spp.

METHODS AND RESULTS

An enrichment PCR method for the detection and identification of Campylobacter jejuni and/or Campylobacter coli in faecal, food and river water samples was applied to 1450 samples of 12 matrix types obtained from a defined geographical area. PCR-positive samples were cultured to yield isolates for typing, and the data for 616 C. jejuni isolates obtained. Serotyping and SmaI macrorestriction profiling using pulsed field gel electrophoresis revealed a high level of diversity within the isolates from each matrix. Campylobacter jejuni and C. coli subtypes indistinguishable from those obtained from human cases were detected in most of the matrices examined. No Campylobacter isolates were isolated from possum faeces.

CONCLUSIONS

Ten of the 12 matrices examined may be involved in the transmission of human campylobacteriosis as they contained Campylobacter subtypes also isolated from clinical cases.

SIGNIFICANCE AND IMPACT OF THE STUDY

Results indicate that, for this rural population, a range of potential transmission routes that could lead to campylobacteriosis exist. Their relative importance needs to be assessed from an exposure assessment standpoint.

Campylobacter spp. in New Zealand raw sheep liver and human campylobacteriosis cases

Sheep liver samples were tested for the presence and numbers of Campylobacter jejuni and C. coli during both spring and autumn. Over the same period, isolates were obtained from human clinical cases from the same geographical area as where the food samples were purchased. A subset of the C. jejuni isolates was typed by both Penner serotyping and pulsed field gel electrophoresis using the restriction enzyme SmaI, to estimate the proportion of liver isolate types that were also isolated from human cases of campylobacteriosis. Of the 272 liver samples tested, 180 (66.2%) contained Campylobacter. Most of the positive samples contained <3 MPN/g of the organism, and only 12 (6.7%) were contaminated at a level exceeding 100 MPN/g. A total of 180 C. jejuni isolates were obtained from sheep liver and another 200 from human faeces. Of these, 212 isolates were randomly selected for typing, half from raw liver and half from human faeces. More than half (61.1%) of the 106 C. jejuni isolates from liver were of subtypes that were also isolated from human cases. While the C. jejuni present in sheep liver were mostly of subtypes also isolated from human cases, the significance of this food as a vehicle of human campylobacteriosis needs to be examined further in respect to other factors such as dose-response information, consumption data, frequency of undercooking and cross contamination.

Tetracycline resistance of Australian Campylobacter jejuni and Campylobacter coli isolates

OBJECTIVES

Tetracycline resistance in Campylobacter is encoded by the tet(O) gene and is usually associated with conjugative plasmids. Little was known about tetracycline resistance in Australian Campylobacter species, therefore we investigated this resistance in 41 Campylobacter jejuni and five Campylobacter coli strains from humans and healthy chickens.

METHODS

Tetracycline MICs were determined for each isolate using an agar dilution method. The distribution and localization of tet(O) on plasmid and chromosomal DNA was determined by Southern-blot experiments. The ability to transfer resistance to recipient strains was examined through conjugation studies. Identity of transconjugants was confirmed by PCR and flaA-restriction fragment length polymorphism analysis.

RESULTS

High-level tetracycline resistance was observed, ranging from 32 to >256 mg/L. Plasmids were detected in 74% of isolates with plasmids between 30 and 40 kb in size most frequently isolated. tet(O) was present in all tetracycline-resistant isolates. In the majority of strains under study the tet(O) gene was chromosomally encoded. Tetracycline resistance of six C. jejuni strains in which tet(O) was plasmid mediated was transferred by conjugation to a C. jejuni recipient strain. Transfer did not occur between tetracycline-resistant C. jejuni strains and a C. coli recipient. No difference in MICs, plasmid carriage and tet(O) localization was detected between human and chicken isolates.

CONCLUSIONS

These data indicate that the tet(O) gene, previously reported in Campylobacter strains throughout the world, is present in Australian Campylobacter. This study will lead to a greater understanding of antibiotic resistance distribution in Campylobacter spp. in Australia.

Bacteriophages as biocontrol agents in food

Bacteriophages possess attributes that appear to be attractive to those searching for novel ways to control foodborne pathogens and spoilage organisms. These phages have a history of safe use, can be highly host specific, and replicate in the presence of a host. Campylobacter, Salmonella, and Listeria monocytogenes and various spoilage organisms have responded to phage control on some foods. However, the use of phages as biocontrol agents is complicated by factors such as an apparent requirement for a threshold level of host before replication can proceed and by suboptimal performance, at best, at temperatures beneath the optimum for the host. This review is a summary of the information on these issues and includes brief descriptions of alternative phage-based strategies for control of foodborne pathogens.

Use of MIDI-fatty acid methyl ester analysis to monitor the transmission of Campylobacter during commercial poultry processing

The presence of Campylobacter spp. on broiler carcasses and in scald water taken from a commercial poultry processing facility was monitored on a monthly basis from January through June. Campylobacter agar, Blaser, was used to enumerate Campylobacter in water samples from a multiple-tank scalder; on prescalded, picked, eviscerated, and chilled carcasses; and on processed carcasses stored at 4 degrees C for 7 or 14 days. The MIDI Sherlock microbial identification system was used to identify Campylobacter-like isolates based on the fatty acid methyl ester profile of the bacteria. The dendrogram program of the Sherlock microbial identification system was used to compare the fatty acid methyl ester profiles of the bacteria and determine the degree of relatedness between the isolates. Findings indicated that no Campylobacter were recovered from carcasses or scald tank water samples collected in January or February, but the pathogen was recovered from samples collected in March, April, May, and June. Processing generally produced a significant (P < 0.05) decrease in the number of Campylobacter recovered from broiler carcasses, and the number of Campylobacter recovered from refrigerated carcasses generally decreased during storage. Significantly (P < 0.05) fewer Campylobacter were recovered from the final tank of the multiple-tank scald system than from the first tank. MIDI similarity index values ranged from 0.104 to 0.928 based on MIDI-fatty acid methyl ester analysis of Campylobacterjejuni and Campylobacter coli isolates. Dendrograms of the fatty acid methyl ester profile of the isolates indicated that poultry flocks may introduce several strains of C. jejuni and C. coli into processing plants. Different populations of the pathogen may be carried into the processing plant by successive broiler flocks, and the same Campylobacter strain may be recovered from different poultry processing operations. However, Campylobacter apparently is unable to colonize equipment in the processing facility and contaminate broilers from flocks processed at later dates in the facility.

Domestically acquired Campylobacter infections in Finland

Campylobacter jejuni isolates (n = 533) from domestic cases diagnosed in Finland during a 3-month peak period were studied. The highest rate was observed among those 70–74 years of age. Domestic C. jejuni isolates were especially frequent in the eastern districts. Six serotypes covered 61% of all C. jejuni isolates.