Isolation of Campylobacter jejuni from groundwater

Roles of Aerotolerance, Biofilm Formation, and Viable but Non-Culturable State in the Survival of Campylobacter jejuni in Poultry Processing Environments

Campylobacter jejuni is one of the most common causes of foodborne human gastroenteritis in the developed world. This bacterium colonizes in the ceca of chickens, spreads throughout the poultry production chain, and contaminates poultry products. Despite numerous on farm intervention strategies and developments in post-harvest antimicrobial treatments, C. jejuni is frequently detected on broiler meat products. This indicates that C. jejuni is evolving over time to overcome the stresses/interventions that are present throughout poultry production and processing. The development of aerotolerance has been reported to be a major survival strategy used by C. jejuni in high oxygen environments. Recent studies have indicated that C. jejuni can enter a viable but non-culturable (VBNC) state or develop biofilm in response to environmental stressors such as refrigeration and freezing stress and aerobic stress. This review provides an overview of different stressors that C. jejuni are exposed to throughout the poultry production chain and the genotypic and phenotypic survival mechanisms, with special attention to aerotolerance, biofilm formation, and development of the VBNC state.

Adhesion, Biofilm Formation, and luxS Sequencing of Campylobacter jejuni Isolated From Water in the Czech Republic

The microaerophilic pathogen Campylobacter jejuni is a leading bacterial cause of human gastroenteritis in developed countries. Even though it has a reputation as a fastidious organism, C. jejuni is widespread and can be easily isolated from various animals, food, and environmental sources. It is suggested that an ability to form biofilms is probably necessary for the survival of C. jejuni under harsh environmental conditions. The first step required for successful biofilm formation is adhesion to a suitable surface. Therefore, in this work, the degree of adhesion was evaluated, followed by characterization and quantification of biofilms using confocal laser scanning microscopy (CLSM). A total of 15 isolates of C. jejuni were used in the experiments (12 isolates from surface and waste waters, 1 human clinical, 1 food and 1 ACTT BAA-2151 collection strain, all samples originated from the Czech Republic). Regardless of the sample origin, all C. jejuni isolates were able to adhere to the polystyrene surface within 30 min, with the number of attached cells increasing with the time of incubation. The resulting data showed that all isolates were able to form complex voluminous biofilms after 24 h of cultivation. The average amount of biovolume ranged from 3.59 × 106 µm3 to 17.50 × 106 µm3 in isolates obtained from different sources of water, 16.79 × 106 µm3 in the food isolate and 10.92 × 106 µm3 in the collection strain. However, the highest amount of biomass was produced by the human clinical isolate (25.48 × 106 µm3). Similar to the quantity, the architecture of the biofilms also differed, from a rugged flat monolayer of cells to large clustered structures. Further, all isolates were tested for the presence of the luxS gene, as the luxS/AI-2 (autoinducer-2) quorum sensing pathway has been previously connected with enhanced biofilm formation. Two isolates originated from surface waters did not possess the luxS gene. These isolates formed thinner and sparser biofilms lacking the presence of significant clusters. However, the ability to adhere to the surface was preserved. The sequencing of the luxS-containing fragments shown a high similarity of the luxS gene among the isolates.

Association between private drinking water wells and the incidence of Campylobacteriosis in Maryland: An ecological analysis using Foodborne Diseases Active Surveillance Network (FoodNet) data (2007-2016)

Campylobacter is a leading cause of bacterial foodborne illness in the United States. Campylobacter infections have most often been associated with food-related risk factors, such as the consumption of poultry and raw milk. Socioeconomic, agricultural and environmental factors, including drinking water source, can also influence the risk of campylobacteriosis. Approximately 19% of Maryland residents rely on private wells as their sole source of water. Given that the federal Safe Drinking Water Act does not regulate the water quality of private wells, these could be important non-foodborne transmission pathways for Campylobacter. To address this issue, data on the number of culture-confirmed cases of Campylobacter infection in Maryland between 2007 and 2016 were obtained from the Foodborne Diseases Active Surveillance Network. Cases were linked by zip code with data from the Maryland well permits registry, the 2010 U.S. Census, the 2016 American Community Survey, and the USDA Agricultural Census. Campylobacteriosis incidence rates and well prevalence were calculated by zip code. Negative binomial regression models were then constructed to evaluate the association between the prevalence of private wells, presence/absence of animal feeding operations and the incidence of campylobacteriosis across the physiographic provinces in Maryland. From 2007 to 2016, a total of 5746 cases of campylobacteriosis were reported in Maryland, and annual incidence rates ranged from 6.65 to 11.59 per 100,000 people. In our statewide analysis, a significant positive association was observed between well prevalence and increased campylobacteriosis incidence at the zip code level (Incidence Rate Ratio (IRR) = 1.35, 95% Confidence Interval (CI) = 1.11, 1.63). A significant positive association was also observed between well prevalence and increased campylobacteriosis incidence in the Appalachian and Coastal provinces of Maryland (IRR = 2.94, 95% CI = 1.11, 7.76 and IRR = 1.70, 95% CI = 1.25, 2.31, respectively). The presence of broiler chicken operations, increasing median age and percentage of residents living in poverty were also significantly associated with campylobacteriosis incidence at the zip code level in some physiographic provinces in Maryland. To our knowledge, these are the first US data to demonstrate an association between prevalence of private wells and campylobacteriosis incidence at the zip code level.

Isotope and microbiome data provide complementary information to identify natural nitrate attenuation processes in groundwater

Natural attenuation processes alleviate the impact of fertilization practices on groundwater resources. Therefore, identifying the occurrence of denitrification has become a requirement for water quality management. Several approaches are useful for this purpose, such as isotopic and microbiological methods, each of them providing distinct but complementary information about denitrification reactions, attenuation rates and their occurrence in the aquifer. In this paper, we investigate the contribution of both approaches to describe denitrification in a consolidated rock aquifer (limestone and marls), with a porosity related to fracture networks located in the northeastern sector of the Osona basin (NE Spain). Isotopic methods indicated the origin of nitrate (fertilization using manure) and that denitrification occurred, reaching a reduction of near 25% of the nitrate mass in groundwater. The studied area could be divided in two zones with distinct agricultural pressures and, consequently, nitrate concentrations in groundwater. Denitrification occurred in both zones and at different levels, indicating that attenuation processes took place all along the whole hydrogeological unit, and that the observed levels could be attributed to a larger flow path or, in a minor extent, to mixing processes that mask the actual denitrification rates. Microbiological data showed a correlation between denitrifier genes and the isotopic composition. However, the groundwater microbiome and the distribution of denitrifying bacteria did not reveal a major influence on the denitrification level observed by isotopic methods. This focuses the interest of microbiological analysis to identify functional genes within the bacteria present in the aquifer. Results indicated that isotopic methods provide information of the overall denitrification ability of the hydrogeological unit, and that genomic data represent the processes actually acting nearby the well. A combination of both approaches is advised to support induced in situ attenuation actions in polluted sites.

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

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

A national investigation of the prevalence and diversity of thermophilic Campylobacter species in agricultural watersheds in Canada

The occurrence and diversity of thermophilic Campylobacter species (C. jejuni, coli, and lari) were studied in water samples from four river basins located across Canada. These basins located in Quebec (Bras d'Henri), Alberta (Oldman), Ontario (South Nation), and British Columbia (Sumas) represented some of the most intensive farming areas in Canada for hog, beef cattle, dairy cattle, and poultry, respectively. This study analyzed 769 water samples collected from 23 monitoring sites with agricultural influence, and four reference sites with limited or no agricultural influence. Water samples were collected bi-weekly over two years and analyzed for Campylobacter using a semi-quantitative minimum probable number (MPN) enrichment protocol. Putative isolates were confirmed by genus- and species-specific multiplex polymerase chain reaction (PCR) assays. A total of 377 (49%) water samples were positive for campylobacters with 355 samples having a cell density ranging from 4 to 4000 MPN L(-1). Campylobacters were more common at agricultural than reference sites in each river basin, although this difference was not significant in the Oldman and South Nation (p > 0.05). Campylobacter was significantly more common in the Bras d'Henri and Sumas (63%) compared to the South Nation (45%) and Oldman (33%) River basins (p < 0.05). C. jejuni, C. coli and C. lari were detected in each river basin, and these species occurred in 45% (n = 168), 34% (n = 128) and 19% (n = 73), of all Campylobacter positive samples, respectively. The remaining Campylobacter positive water samples without these three species (n = 67; 18%) were identified as other Campylobacter species. C. jejuni was the predominant species occurring in the Sumas, Oldman and South Nation River basins. However, in the Bras d'Henri River basin with intensive hog production, C. coli was the predominant species. This study found campylobacters to be common in some agricultural systems with intensive livestock farming activities, and different river basins could have strikingly different profiles of either C. jejuni or C. coli as the predominant waterborne thermophilic Campylobacter species.

A large waterborne gastroenteritis outbreak in central Greece, March 2012: challenges for the investigation and management

In March 2012, there was an unusual increase of gastroenteritis cases in a district with 37,264 inhabitants in central Greece. It was estimated that more than 3600 people developed symptoms. A 1:1 case-control study showed that consumption of tap water was a risk factor for acquiring infection [odds ratio (OR) 2.18, 95% confidence interval (CI) 1.11-4.28]. Descriptive data, low gastroenteritis incidence in adjacent areas with different water supply systems, and water-quality data further supported the hypothesis of a waterborne outbreak. Thirty-eight stool samples were positive for rotavirus. Bacterial indicators of recent faecal contamination were detected in samples from the water source and ice cubes from a local production enterprise. Molecular epidemiology of rotavirus strains, apart from the common strain, G3[P8], identified the unusual G/P combination G2P[8]. Water sanitation measures contributed to the control of the outbreak. This outbreak demonstrated the need for the cooperation of laboratories with different expertise and the importance of early notification of waterborne gastroenteritis outbreaks.

The role of environmental reservoirs in human campylobacteriosis

Campylobacteriosis is infection caused by the bacteria Campylobacter spp. and is considered a major public health concern. Campylobacter spp. have been identified as one of the most common causative agents of bacterial gastroenteritis. They are typically considered a foodborne pathogen and have been shown to colonise the intestinal mucosa of all food-producing animals. Much emphasis has been placed on controlling the foodborne pathway of exposure, particularly within the poultry industry, however, other environmental sources have been identified as important contributors to human infection. This paper aims to review the current literature on the sources of human exposure to Campylobacter spp. and will cover contaminated poultry, red meat, unpasteurised milk, unwashed fruit and vegetables, compost, wild bird faeces, sewage, surface water, ground water and drinking water. A comparison of current Campylobacter spp. identification methods from environmental samples is also presented. The review of literature suggests that there are multiple and diverse sources for Campylobacter infection. Many environmental sources result in direct human exposure but also in contamination of the food processing industry. This review provides useful information for risk assessment.

Fun on the farm: evaluation of a lesson to teach students about the spread of infection on school farm visits

Background

School visits to farms are a positive educational experience but pose risks due to the spread of zoonotic infections. A lesson plan to raise awareness about microbes on the farm and preventative behaviours was developed in response to the Griffin Investigation into the E. coli outbreak associated with Godstone Farm in 2009. This study evaluated the effectiveness of the delivery of the lesson plan in increasing knowledge about the spread of infection on the farm, amongst school students.

Methods

Two hundred and twenty-five 9–11 year old students from seven junior schools in England participated. Two hundred and ten students filled in identical questionnaires covering microbes, hand hygiene, and farm hygiene before and after the lesson. Statistical analysis assessed knowledge change using difference in percentage correct answers.

Results

Significant knowledge improvement was observed for all sections. In the ‘Farm Hygiene’ section, girls and boys demonstrated 18% (p<0.001) and 11% (p<0.001) improvement, respectively (girls vs. boys p<0.004). As girls had lower baseline knowledge the greater percentage improvement resulted in similar post intervention knowledge scores between genders (girls 80%, boys 83%).

Conclusions

The lesson plan was successful at increasing awareness of microbes on the farm and infection prevention measures and should be used by teachers in preparation for a farm visit.

Campylobacter infection associated with consumption of duck liver pâté: a retrospective cohort study in the setting of near universal exposure

SUMMARY

A retrospective cohort study was performed following several reported cases of gastrointestinal illness after a catered event. The attack rate was 45/77 (58·4%) by clinical case definition, with four individuals confirmed to have Campylobacter. There was near universal exposure to most foodstuffs served; consumption of duck liver pâté [relative risk (RR) 2·53, 95% confidence interval (CI) 1·05-6·10], mixed leaf salad (RR 2·91, 95% CI 1·22-6·92) and table water (RR undefined, P < 0·01) were associated with illness in univariate analysis, with only the latter associated in the final multivariable model (P < 0·001). Samples of cooked duck liver pâté subsequently prepared using identical methods at the venue were contaminated with Campylobacter jejuni and C. coli; water sampling was negative. Making inferences about causation in the presence of near universal exposures in this study required consideration of the limitations of statistical analysis, with the most compelling evidence of the causal role of inadequately prepared duck liver pâté provided by environmental investigation.

Binational outbreak of Guillain-Barré syndrome associated with Campylobacter jejuni infection, Mexico and USA, 2011

In June 2011, a cluster of suspected cases of Guillain-Barré syndrome (GBS), which can follow Campylobacter jejuni infection, was identified in San Luis Río Colorado (SLRC), Sonora, Mexico and Yuma County, Arizona, USA. An outbreak investigation identified 26 patients (18 from Sonora, eight from Arizona) with onset of GBS 4 May-21 July 2011, exceeding the expected number of cases (n = 1-2). Twenty-one (81%) patients reported antecedent diarrhoea, and 61% of 18 patients tested were seropositive for C. jejuni IgM antibodies. In a case-control study matched on age group, sex, ethnicity, and neighbourhood of residence, all Arizona GBS patients travelled to SLRC during the exposure period vs. 45% of matched controls (matched odds ratio 8·1, 95% confidence interval 1·5-∞). Exposure information and an environmental assessment suggested that GBS cases resulted from a large outbreak of C. jejuni infection from inadequately disinfected tap water in SLRC. Binational collaboration was essential in investigating this cross-border GBS outbreak, the first in mainland North America since 1976.

Characterization of mono- and mixed-culture Campylobacter jejuni biofilms

Campylobacter jejuni, one of the most common causes of human gastroenteritis, is a thermophilic and microaerophilic bacterium. These characteristics make it a fastidious organism, which limits its ability to survive outside animal hosts. Nevertheless, C. jejuni can be transmitted to both humans and animals via environmental pathways, especially through contaminated water. Biofilms may play a crucial role in the survival of the bacterium under unfavorable environmental conditions. The goal of this study was to investigate survival strategies of C. jejuni in mono- and mixed-culture biofilms. We grew monoculture biofilms of C. jejuni and mixed-culture biofilms of C. jejuni with Pseudomonas aeruginosa. We found that mono- and mixed-culture biofilms had significantly different structures and activities. Monoculture C. jejuni biofilms did not consume a measurable quantity of oxygen. Using a confocal laser scanning microscope (CLSM), we found that cells from monoculture biofilms were alive according to live/dead staining but that these cells were not culturable. In contrast, in mixed-culture biofilms, C. jejuni remained in a culturable physiological state. Monoculture C. jejuni biofilms could persist under lower flow rates (0.75 ml/min) but were unable to persist at higher flow rates (1 to 2.5 ml/min). In sharp contrast, mixed-culture biofilms were more robust and were unaffected by higher flow rates (2.5 ml/min). Our results indicate that biofilms provide an environmental refuge that is conducive to the survival of C. jejuni.

Drinking water as the source of Campylobacter coli infection in grandparent heavy breeders

The aim of the present study was the molecular identification of a common source of infection of Campylobacter coli in two grandparent breeder farms. Campylobacter jejuni and C. coli were isolated from well water and cloacal swabs from grandparent chickens. Colonies were genotyped using restriction fragment length polymorphism-flaA gene, pulsed field gel electrophoresis and multi-locus sequence typing. The same genotype of C. coli was found in both farms and in the well from which drinking water was supplied to the farms. The well water was epidemiologically linked as the source of C. coli infection. The molecular identification for epidemiological source-tracking of C. coli in breeder farms could aid in combating the colonization of this pathogen and therefore to reduce their incidence in human campylobacteriosis.

Increase in acid tolerance of Campylobacter jejuni through coincubation with amoebae

Campylobacter jejuni is a recognized and common gastrointestinal pathogen in most parts of the world. Human infections are often food borne, and the bacterium is frequent among poultry and other food animals. However, much less is known about the epidemiology of C. jejuni in the environment and what mechanisms the bacterium depends on to tolerate low pH. The sensitive nature of C. jejuni stands in contrast to the fact that it is difficult to eradicate from poultry production, and even more contradictory is the fact that the bacterium is able to survive the acidic passage through the human stomach. Here we expand the knowledge on C. jejuni acid tolerance by looking at protozoa as a potential epidemiological pathway of infection. Our results showed that when C. jejuni cells were coincubated with Acanthamoeba polyphaga in acidified phosphate-buffered saline (PBS) or tap water, the bacteria could tolerate pHs far below those in their normal range, even surviving at pH 4 for 20 h and at pH 2 for 5 h. Interestingly, moderately acidic conditions (pH 4 and 5) were shown to trigger C. jejuni motility as well as to increase adhesion/internalization of bacteria into A. polyphaga. Taken together, the results suggest that protozoa may act as protective hosts against harsh conditions and might be a potential risk factor for C. jejuni infections. These findings may be important for our understanding of C. jejuni passage through the gastrointestinal tract and for hygiene practices used in poultry settings.

Campylobacter excreted into the environment by animal sources: prevalence, concentration shed, and host association

An intensive study of 443 isolates of Campylobacter jejuni and Campylobacter coli from 2031 fecal samples excreted by animal sources including cattle, sheep, and pigs, a range of wild and domesticated avian species and pets is described. The prevalence found in the majority of animal sources ranged from 22% to 28% with poultry being highest at 41% and cats and dogs lowest (<5%). The average count excreted for each animal source was found not to be significantly different ranging from approximately 10(2) to 10(5) cfu/g. Multilocus sequence typing (MLST) identified phylogenies that exhibited host specificity. A number of clonal complexes (CCs) and sequence types (STs) were characteristic of particular hosts (e.g., CC-179, ST-637, and ST-1341 found only in pigeons and gulls). Analysis of genetic distance demonstrated numerous significant differences in the distribution of MLST types (CC, ST, and allele) between animal sources. Host association was quantified using structure that correctly assigned the nine animal sources with accuracies of 28%, 24%, and 55% at the CC, ST, and allele levels, respectively. This is substantially higher than would be expected by random allocation (11%) but farmyard poultry had the lowest assignment accuracy (13%, 13%, and 21%) suggesting that isolates were shared with a wide range of other animals. This study demonstrates the link between MLST type and host and provides data that can be used in risk assessment and food attribution models. Further, it demonstrates the applicability of MLST to characterize Campylobacter strains from a broad range of environmental sources.

Survival of Campylobacter jejuni and Escherichia coli in groundwater during prolonged starvation at low temperatures

AIMS

To evaluate the survival of Campylobacter jejuni relative to that of Escherichia coli in groundwater microcosms varying in nutrient composition.

METHODS AND RESULTS

Studies were conducted in groundwater and deionized water incubated for up to 470 days at 4 degrees C. Samples were taken for culturable and total cell counts, nutrient and molecular analysis. Die-off in groundwater microcosms was between 2.5 and 13 times faster for C. jejuni than for E. coli. Campylobacter jejuni had the lowest decay rate and longest culturability in microcosms with higher dissolved organic carbon (4 mg l(-1)). Escherichia coli survival was the greatest when the total dissolved nitrogen (12.0 mg l(-1)) was high. The transition of C. jejuni to the coccoid stage was independent of culturability.

CONCLUSION

The differences in the duration of survival and response to water nutrient composition between the two organisms suggest that E. coli may be present in the waters much longer and respond to water composition much differently than C. jejuni.

SIGNIFICANCE AND IMPACT OF THE STUDY

The data from these studies would aid in the evaluation of the utility of E. coli as an indicator of C. jejuni. This study also provided new information about the effect of nutrient composition on C. jejuni viability.

A large multi-pathogen waterborne community outbreak linked to faecal contamination of a groundwater system, France, 2000

A large waterborne outbreak of infection that occurred during August 2000 in a local community in France was investigated initially via a rapid survey of visits to local physicians. A retrospective cohort study was then conducted on a random cluster sample of residents. Of 709 residents interviewed, 202 (28.5%) were definite cases (at least three liquid stools/day or vomiting) and 62 (8.7%) were probable cases (less than three liquid stools/day or abdominal pain). Those who had drunk tap water had a three-fold increased risk for illness (95% CI 2.4-4.0). The risk increased with the amount of water consumed (chi-square trend: p < 0.0001). Bacteriological analyses of stools were performed for 35 patients and virological analyses for 24 patients. Campylobacter coli, group A rotavirus and norovirus were detected in 31.5%, 71.0% and 21% of samples, respectively. An extensive environmental investigation concluded that a groundwater source to this community had probably been contaminated by agricultural run-off, and a failure in the chlorination system was identified. This is the first documented waterborne outbreak of infection involving human C. coli infections. A better understanding of the factors influencing campylobacter transmission between hosts is required.

Comparison of Escherichia coli and Campylobacter jejuni transport in saturated porous media

Due to the difficulties in testing for specific pathogens, water samples are tested for the presence of nonpathogenic indicator organisms to determine whether a water supply has been contaminated by fecal material. An implicit assumption in this approach is that where pathogenic microorganisms are present fecal indicator organisms are present as well; yet surprisingly few studies have been conducted that directly compare the transport of indicator organisms with pathogenic organisms in ground water environments. In this study we compared the cell properties and transport of Escherichia coli, a commonly used indicator organism, and Campylobacter jejuni, an important enteropathogen commonly found in agricultural wastes, through saturated porous media. Differences in cell properties were determined by measuring cell geometry, hydrophobicity, and electrophoretic mobility. Transport differences were determined by conducting miscible displacement experiments in laboratory columns. Under the experimental conditions tested, C. jejuni was much more negatively charged and more hydrophobic than E. coli. In addition, C. jejuni cells were slightly longer, narrower, and less spherical than E. coli. The variations in cell properties, primarily surface charge, resulted in significant differences in transport between these two microorganisms, with the transport of C. jejuni exceeding that of E. coli when conditions favored low attachment rates, thus calling into question the usefulness of using E. coli as an indicator organism for this important pathogen.

Transcriptional and translational expression patterns associated with immobilized growth of Campylobacter jejuni

AlthoughCampylobacter jejuniis a leading cause of food-borne illness, little is known about the mechanisms by which this pathogen mediates prolonged environmental survival or host cell virulence. Although these behaviours represent distinct phenotypes, they share a common requirement of an immobilized state. In order to understand the cellular mechanisms that facilitate a surface-associated lifestyle, transcriptional and translational expression profiles were determined for sessile and planktonicC. jejuni. These investigations indicate that the immobilized bacteria undergo a shift in cellular priorities away from metabolic, motility and protein synthesis capabilities towards emphasis on iron uptake, oxidative stress defence and membrane transport. This pattern of expression partially overlaps those reported for Campylobacter during host colonization, as well as for other species of bacteria involved in biofilms, highlighting common adaptive responses to the conserved challenges within each of these phenotypes. The adaptation of Campylobacter to immobilized growth may represent a quasi-differentiated state that functions as a foundation for further specialization towards phenotypes such as biofilm formation or host cell virulence.

Detection ofCampylobacter jejuniin Dairy Farm Environmental Samples Using SYBR Green Real-Time Polymerase Chain Reaction

The aim of this study was to evaluate a SYBR Green based real-time PCR assay using well-characterized primers to detect Campylobacter jejuni in naturally contaminated dairy farm environmental samples. Specificity of the assay was determined with 62 C. jejuni strains and 120 non-C. jejuni strains. Peak melting temperature obtained with melting curves specific for C. jejuni was 77.5 degrees C. Standard curves were constructed using mean threshold cycle (C(T)) and various concentrations of C. jejuni ranging from 10(0) to 10(8) colony forming units (CFU)/mL, which resulted in a linear relationship between C(T) and log input DNA. Correlation coefficients of standard curves based on pure culture of C. jejuni in broth and spiked cells in lagoon water were R(2) = 0.995 (slope = 3.21) and R(2) = 0.988 (slope = 3.22), respectively, and sensitivity limits were <10 and >10(3) CFU/mL, respectively. After 24-h enrichment, total C. jejuni counts of all samples spiked with 10(0) CFU/mL reached >10(5) CFU/mL, and the detection limit was improved from >10(3) CFU/mL to <10 CFU/mL of inoculum in broth. Eighty-two dairy farm environmental samples, including fecal slurry, feed/silage, lagoon water, drinking water, bulk tank milk, farm soil, and bedding material, were analyzed. The real-time PCR assay detected C. jejuni in 25 (30.4%) of 82 samples, with 17 (68%) of these samples being culture positive for C. jejuni. All samples that were positive by standard culture methods were also positive by the real-time PCR method. Mean C( T ) values of 48-h enriched cultures for 17 PCR-positive/culture-positive samples and eight PCR-positive/culture-negative samples were 21.4 +/- 3.6, and 34.6 +/- 1.5 (p < 0.0001), respectively. C( T ) values for negative samples were >38.0. These results indicate that the SYBR Green real-time PCR assay provides a specific, reproducible, and simple method for detecting C. jejuni in dairy farm environmental samples.

A novel method for isolation of Campylobacter spp. from environmental samples, involving sample processing, and blood- and antibiotic-free medium

AIMS

To develop a method that involves sample processing, and blood- and antibiotic-free medium for isolation and enumeration of Campylobacter spp. from environmental samples.

METHODS AND RESULTS

The sample processing (preT) was standardized to minimize the population of competing bacteria. A blood- and antibiotic-free differential, Kapadnis-Baseri medium (KB medium) was formulated and tested for isolation of Campylobacter spp. in comparison with CAT medium. PreT-KB method was evaluated in comparison with the conventional viable count method and with the conventional most probable number (C. MPN) method for enumeration of Campylobcater from environmental samples. The results indicated that sample processing significantly reduced population of competing bacteria. The KB medium selected Gram-negative bacteria and differentiated Campylobacter from lactose-fermenting competing bacteria. The population of Campylobacter detected by preT-KB method was similar to that by conventional viable count method. While, the population of Campylobacter spp. determined by preT-KB method was higher than that by C. MPN method. In addition, the preT-KB method detected antibiotic sensitive campylobacters.

CONCLUSION

The preT minimizes population of competing bacteria and the KB medium selects Gram-negative bacteria and differentiates Campylobacter from them. Therefore, Campylobacter can be isolated from environmental samples without using antibiotics.

SIGNIFICANCE AND IMPACT OF THE STUDY

The preT-KB method is simple and facilitates isolation of antibiotic sensitive and enumeration of Campylobacter in the environmental samples. Therefore, the new method will be useful for isolation and enumeration of Campylobacter from water, food and sewage samples. Besides, it would also detect antibiotic-sensitive campylobacters, which are not detected by conventional viable count and MPN methods.

Comparison of survival of Campylobacter jejuni in the phyllosphere with that in the rhizosphere of spinach and radish plants

Campylobacter jejuni has been isolated previously from market produce and has caused gastroenteritis outbreaks linked to produce. We have tested the ability of this human pathogen to utilize organic compounds that are present in leaf and root exudates and to survive in the plant environment under various conditions. Carbon utilization profiles revealed that C. jejuni can utilize many organic acids and amino acids available on leaves and roots. Despite the presence of suitable substrates in the phyllosphere and the rhizosphere, C. jejuni was unable to grow on lettuce and spinach leaves and on spinach and radish roots of plants incubated at 33 degrees C, a temperature that is conducive to its growth in vitro. However, C. jejuni was cultured from radish roots and from the spinach rhizosphere for at least 23 and 28 days, respectively, at 10 degrees C. This enteric pathogen also persisted in the rhizosphere of spinach for prolonged periods of time at 16 degrees C, a temperature at which many cool-season crops are grown. The decline rate constants of C. jejuni populations in the spinach and radish rhizosphere were 10- and 6-fold lower, respectively, than on healthy spinach leaves at 10 degrees C. The enhanced survival of C. jejuni in soil and in the rhizosphere may be a significant factor in its contamination cycle in the environment and may be associated with the sporadic C. jejuni incidence and campylobacteriosis outbreaks linked to produce.

Genetic diversity of Campylobacter jejuni isolates from farm animals and the farm environment

The genetic diversity of Campylobacter jejuni isolates from farm animals and their environment was investigated by multilocus sequence typing (MLST). A total of 30 genotypes, defined by allelic profiles (assigned to sequence types [STs]), were found in 112 C. jejuni isolates originating in poultry, cattle, sheep, starlings, and slurry. All but two of these genotypes belonged to one of nine C. jejuni clonal complexes previously identified in isolates from human disease and retail food samples and one clonal complex previously associated with an environmental source. There was some evidence for the association of certain clonal complexes with particular farm animals: isolates belonging to the ST-45 complex predominated among poultry isolates but were absent among sheep isolates, while isolates belonging to the ST-61 and ST-42 complexes were predominant among sheep isolates but were absent from the poultry isolates. In contrast, ST-21 complex isolates were distributed among the different isolation sources. Comparison with MLST data from 91 human disease isolates showed small but significant genetic differentiation between the farm and human isolates; however, representatives of six clonal complexes were found in both samples. These data demonstrate that MLST and the clonal complex model can be used to identify and compare the genotypes of C. jejuni isolates from farm animals and the environment with those from retail food and human disease.

A comparison of Campylobacter jejuni enteritis incidence rates in high- and low-poultry-density counties: Michigan 1992-1999

To compare the incidence of Campylobacter jejuni enteritis in high- and low-poultry-density counties in Michigan between the years 1992 and 1999, an ecological study was conducted in the state of Michigan. A log-linear model was used to compare yearly, seasonal, age, and gender-specific incidence rates between county groupings. Counties with a high poultry density had a higher overall incidence of C. jejuni enteritis, particularly among children and young adults, compared with counties with low poultry density. The findings suggest that living in high-poultry-density counties is associated with higher odds for C. jejuni enteritis. This may be due to occupational exposure among poultry workers in these counties, but the findings in children suggest that indirect or environmental exposures may also play a role. Future studies should be conducted to investigate these issues.

Cattle and sheep farms as reservoirs of Campylobacter

AIM

This is a review of the natural Campylobacter colonization and transmission among ruminant livestock in the dairy farm environment.

METHODS AND RESULTS

Using cultural detection methods and enumeration techniques the distribution of Campylobacter in ruminant animals at birth, on the farm, at slaughter and in the farm environment have been examined. Colonization and shedding rates are higher among young animals while patterns of shedding in adult animals may be seasonal. Stored and land-dispersed slurries provide a reservoir for scavenging birds and flies and a source for runoff.

CONCLUSIONS

The dairy farm plays a significant role in the dissemination of Campylobacter subtypes that can cause disease in the human community.

SIGNIFICANCE AND IMPACT OF STUDY

An understanding of the role of the dairy farm in the environmental cycle of Campylobacter is required in order to devise intervention strategies.

Pathogens and manure management systems: a review

There has been an increasing concern about the effects of pathogens that are present in animal manure on humanand animal health. In recent years, outbreaks of food-borne diseases associated with the consumption of animal products havereceived much attention from the media in North America and Europe, leading to increased consumer concerns about the safety of their food supply. The health risks associated with animal operations depend on various factors. The most important ones appear to be related to the animal species being reared and the concentration of pathogenic microorganisms in animal manure. The ability of the pathogens to survive for long periods and through treatment to remain infective in the environment until ingested by human or animal host is an added concern. On the other hand, the role of livestock in most waterborne bacterial outbreaks has often been difficult to clarify since both humans and various wildlife species can shed the same microorganisms and thereby serve as sources of infection. This paper summarizes existing information on the main microbial pathogens present in livestock wastes, and discusses the impact of livestock wastes and agricultural drainage on microbiological quality of water, as well as available management and treatment technologies to minimize the prevalence of pathogens in animal wastes. Despite the fact that most disease outbreaks have been associated with food poisoning by cross-contamination during meat or milk processing and during finished product storage this review shows that a number of best management practices and technical solutions have been developed in the last few years that can be effective tools in minimizing the spread of pathogens from livestock operations in the environment.

Prevalence of Campylobacter jejuni, Campylobacter lari, and Campylobacter coli in different ecological guilds and taxa of migrating birds

A total of 1,794 migrating birds trapped at a coastal site in southern Sweden were sampled for detection of Campylobacter spp. All isolates phenotypically identified as Campylobacter jejuni and a subset of those identified as non-C. jejuni were identified to the species level by PCR-based techniques. C. jejuni was found in 5.0% of the birds, Campylobacter lari was found in 5.6%, and Campylobacter coli was found in 0.9%. An additional 10.7% of the tested birds were infected with hippurate hydrolysis-negative Campylobacter spp. that were not identified to the species level. The prevalence of Campylobacter spp. differed significantly between ecological guilds of birds. Shoreline-foraging birds feeding on invertebrates and opportunistic feeders were most commonly infected (76.8 and 50.0%, respectively). High prevalence was also shown in other ground-foraging guilds, i.e., ground-foraging invertebrate feeders (11.0%), ground-foraging insectivores (20.3%), and plant-eating species (18.8%). Almost no Campylobacter spp. were found in ground-foraging granivores (2.3%), arboreal insectivores (0.6%), aerial insectivores (0%), or reed- and herbaceous plant-foraging insectivores (3.5%). During the autumn migration, a high proportion of samples from juveniles were positive (7.1% in passerines, 55.0% in shorebirds), indicating transmission on the breeding grounds or during the early part of migration. Prevalence of Campylobacter spp. was associated with increasing body mass among passerine bird species. Furthermore, prevalence was higher in short-distance migrants wintering in Europe than in long-distance migrants wintering in Africa, the Middle East, or Asia. Among ground-foraging birds of the Muscicapidae, those of the subfamily Turdinae (i.e., Turdus spp.) showed a high prevalence of Campylobacter spp., while the organism was not isolated in any member of the subfamily Muscicapinae (i.e., Erithacus and Luscinia). The prevalence of Campylobacter infection in wild birds thus seems to be linked to various ecological and phylogenetic factors, with great variations in carriership between different taxa and guilds.

Campylobacter colonization in poultry: sources of infection and modes of transmission

Since its recognition as a human pathogen in the early 1970s, Campylobacter jejuni has now emerged as the leading bacterial cause of food-borne gastroenteritis in developed countries. Poultry, particularly chickens, account for the majority of human infections caused by Campylobacter. Reduction or elimination of this pathogen in the poultry reservoir is an essential step in minimizing the public health problem; however, farm-based intervention measures are still not available because of the lack of understanding of the ecological aspects of C. jejuni on poultry farms. Although Campylobacter is highly prevalent in poultry production systems, how poultry flocks become infected with this organism is still unknown. Many investigations indicate that horizontal transmission from environmental sources is the primary route of flock infections by Campylobacter. However, some recent studies also suggest the possibility of vertical transmission from breeder to progeny flocks. The transmission of the organism is not well understood, but it is likely to be through both vertical and horizontal transmission and may be affected by the immune status of the poultry host and the environmental conditions in the production system. Intervention strategies for Campylobacter infection in poultry should consider the complex nature of its transmission and may require the use of multiple approaches that target different segments of the poultry production system.

Survival of Campylobacter jejuni in biofilms isolated from chicken houses

Campylobacter jejuni is a thermophilic and microaerophilic enteric pathogen associated with poultry. Biofilms may be a source of C. jejuni in poultry house water systems since they can protect constituent microorganisms from environmental stress. In this study, the viability of C. jejuni in biofilms of gram-positive chicken house isolates (P1, Y1, and W1) and a Pseudomonas sp. was determined using a cultural method (modified brucella agar) and direct viable count (DVC). Two-day biofilms grown on polyvinyl chloride (PVC) coupons in R2A broth at 12 and 23 degrees C were incubated with C. jejuni for a 6-h attachment period. Media were then refreshed every 24 h for 7 days to allow biofilm growth. Two-day biofilms of P1, Y1, and Pseudomonas spp. enhanced attachment (P < 0.01) of C. jejuni (4.74, 4.62, and 4.78 log cells/cm2, respectively) compared to W1 and controls without preexisting biofilm (4.31 and 4.22 log cells/cm2, respectively). On day 7, isolates P1 and Y1 and Pseudomonas biofilms covered 5.4, 7.0, and 21.5% of the surface, respectively, compared to 4.9% by W1. Viable C. jejuni on the surface decreased (P < 0.05) with time, with the greatest reduction occurring on surfaces without a preexisting biofilm. The number of viable C. jejuni determined by DVC was greater than that determined by the cultural method, indicating that C. jejuni may form a viable but nonculturable state within the biofilm. Both DVC and the cultural method indicate that biofilms enhance (P < 0.01) the survival of C. jejuni during incubation at 12 and 23 degrees C over a 7-day period.

Enumeration of Campylobacter in New Zealand recreational and drinking waters

AIMS

To use a published polymerase chain reaction (PCR) method for the detection and identification of thermotolerant Campylobacter species (Camp. jejuni, Camp. coli and Camp. lari) in tandem with a Most Probable Number (MPN) technique to enumerate these species in water samples.

METHODS AND RESULTS

An initial study of 42 river water samples compared the use of conventional culture and PCR methods for the detection of Campylobacter in MPN enrichment tubes. It was found that all samples positive by culture were also positive by PCR. Thirty-seven percent more MPN tubes were positive by PCR compared with culture. The MPN/PCR technique was subsequently applied to 96 additional samples collected from rivers, drinking, roof and shallow ground water. Campylobacter was especially prevalent in river water (60% positive) and shallow ground water (75% positive) samples. Drinking water (29.2% positive) and roof water (37.5% positive) also contained Campylobacter, but the numbers detected were very low (maximum 0.3 and 0.56 MPN 100 ml-1, respectively).

CONCLUSION

River waters contained Campylobacter at higher levels than any other water type and in a high percentage of the samples. Although Campylobacter was present in treated drinking water, the levels detected were low.

SIGNIFICANCE AND IMPACT OF THE STUDY

These results suggest that water may act as a significant transmission route for human campylobacteriosis.

Microbiological safety of drinking water

Emerging pathogens in drinking water have become increasingly important during the decade. These include newly-recognized pathogens from fecal sources such as Cryptosporidium parvum, Campylobacter spp., and rotavirus, as well as pathogens that are able to grow in water distribution systems, like Legionella spp., mycobacteria, and aeromonads. To perform a risk analysis for the pathogens in drinking water, it is necessary to understand the ecology of these organisms. The ecology of the drinking-water distribution system has to be evaluated in detail, especially the diversity and physiological properties of water bacteria. The interactions between water bacteria and (potential) pathogens in such diverse habitats as free water and biofilms are essential for the survival or growth of hygienically relevant organisms in drinking water. Results of epidemiological studies together with ecological data are the basis for effective resource protection, water treatment, and risk assessment.

The effects of UVB and temperature on the survival of natural populations and pure cultures of Campylobacter jejuni, Camp. coli, Camp. lari and urease-positive thermophilic campylobacters (UPTC) in surface waters

AIMS

To determine whether diurnal and seasonal variations in campylobacters in surface waters result from the effects of temperature and u.v. radiation, and whether natural populations of Campylobacter lari and urease-positive thermophilic campylobacters (UPTC) from birds survive better in surface waters than Camp. jejuni from sewage.

METHODS AND RESULTS

Natural populations of Camp. lari and UPTC in sea water, and Camp. jejuni in river water, were exposed to artificial sunlight (equivalent to a sunny day in June). Both populations became non-culturable within 30 min, with T90s of 15 min and 25 min, respectively. Cultures of Camp. jejuni became non-culturable within 40 min and those of Camp. coli, Camp. lari and UPTC, within 60 min. In darkness, survival was temperature-dependent. Natural populations took 12 h at 37 degrees C and 5 days at 4 degrees C to become non-culturable in sea water, and slightly less in river water. Cultures of Camp. lari and UPTCs survived for significantly longer than Camp. jejuni and Camp. coli. Loss of culturability for all isolates was most rapid at 37 degrees C and slowest at 4 degrees C. Newly isolated strains from sea water and river water behaved in an almost identical manner to NCTC strains.

CONCLUSION

Campylobacter lari and UPTCs survive for longer in surface waters than Camp. jejuni and Camp. coli, particularly in the dark. Low Campylobacter numbers in coastal waters in the summer, especially in the afternoon, are due to the combined effects of higher temperatures and higher levels of u.v. radiation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Campylobacter lari and UPTCs from birds predominate in bathing waters in Morecambe Bay because they are better able to survive; they also originate from closer to the shore than Camp. jejuni and Camp. coli in sewage effluent, which survive poorly and die before the incoming tide reaches the shore. The predominance of Camp. jejuni in river water results from its dominance of the inputs and not from its ability to survive.

Fecal shedding of Campylobacter and Arcobacter spp. in dairy cattle

Campylobacter jejuni, Campylobacter coli, and Arcobacter spp. were detected in feces of healthy dairy cows by highly specific multiplex-PCR assays. For C. jejuni, at this one-time sampling, cows from 80.6% of farm operations (n = 31) and 37.7% of individual dairy cattle fecal samples (n = 2,085) were positive. Farm management factors were correlated with prevalence in herds in which >25% of cows were positive for C. jejuni. Statistical significance was set at a P of 0.20. Using these criteria, application of manure with broadcast spreaders (P = 0.17), feeding of whole cottonseed or hulls (P = 0.17) or alfalfa (P = 0.15), and accessibility of feed to birds (P = 0.17) were identified as possible risk factors for C. jejuni infection. C. coli was detected in at least one animal in 19.4% of operations and 1.8% of individual cows (n = 2,085). At the herd level, use of broadcaster spreaders was not a risk factor for C. coli infection. For Arcobacter, cows from 71% of dairy operations (n = 31) and 14.3% of individual dairy cattle fecal samples (n = 1,682) were positive. At the herd level, for Arcobacter spp., feeding of alfalfa (P = 0.11) and use of individual waterers (P = 0.19) were protective. This is the first description of Arcobacter spp. in clinically healthy dairy cattle and the first attempt to correlate their presence with C. jejuni.

Intermittent shedding of thermophilic campylobacters by sheep at pasture

The rates at which sheep on different types of pasture shed campylobacters in their faeces were measured over 12 months. Overall, shedding of campylobacters at pasture was between a third and a half of the carriage rate (92%) of the intestines of sheep at slaughter. Shedding was highest during saltmarsh grazing, followed by upland fell and farm grazing. The rate of shedding varied at different times of the year, with the highest rates (100%) coinciding with lambing, weaning, and movement onto new pasture. The lowest rates (0%) occurred when sheep were fed on hay and silage. On the farm, low rates occurred during the whole of gestation, both when the sheep were indoors and outdoors. Campylobacter jejuni was the main species isolated and survived for up to 4 d in sheep faeces. Lambs became colonized by Campylobacter within 1-5 d of being born. Ewes, which were not shedding campylobacters prior to lambing, started to shed after lambing, and ewes which were shedding low numbers of Campylobacter before lambing, increased the numbers of bacteria being shed after lambing.