Thermophilic campylobacters in surface water: a potential risk of campylobacteriosis

Campylobacter jejuni Outbreak Linked to Raw Oysters in Rhode Island, 2021

Oysters and other shellfish are not a food that is commonly highlighted as high risk for Campylobacter contamination. The Rhode Island Department of Health (RIDOH) conducted a multiagency investigation of a Campylobacter jejuni outbreak that was linked to the consumption of raw oysters; the first such outbreak was detected in Rhode Island. The environmental investigation identified birds as the likely source of contamination of the aquacultured oysters. As a result of this outbreak response, several investigative processes and best practice recommendations are offered. 1) RIDOH will be including exposure to raw shellfish as a question on their case report forms to better identify future oyster-related Campylobacter clusters. 2) It is important that shellfish aquaculture farms be aware of the risks of using floating gear to hold oyster cages and of the importance of using bird abatement to keep birds off floating aquaculture gear to prevent contamination of oysters from bird feces. 3) It should be recognized that fecal coliform water samples collected near an oyster aquaculture farm may not act as an adequate indicator for the presence of Campylobacter. 4) For the first time, Rhode Island has developed guidelines for the closure and reopening of oyster harvest areas due to contamination with Campylobacter. It is hoped that increased awareness and mitigation of the described risk factors will help prevent future similar outbreaks of illness.

Tracing the animal sources of surface water contamination with Campylobacter jejuni and Campylobacter coli

Campylobacter jejuni and C. coli, the primary agents of human bacterial gastroenteritis worldwide, are widespread in surface water. Several animal sources contribute to surface water contamination with Campylobacter, but their relative contributions thus far remained unclear. Here, the prevalence, genotype diversity, and potential animal sources of C. jejuni and C. coli strains in surface water in the Netherlands were investigated. It was also assessed whether the contribution of the different animal sources varied according to surface water type (i.e. agricultural water, surface water at discharge points of wastewater treatment plants [WWTPs], and official recreational water), season, and local livestock (poultry, pig, ruminant) density. For each surface water type, 30 locations spread over six areas with either high or low density of poultry, ruminants, or pigs, were sampled once every season in 2018-2019. Campylobacter prevalence was highest in agricultural waters (77%), and in autumn and winter (74%), and lowest in recreational waters (46%) and in summer (54%). In total, 76 C. jejuni and 177 C. coli water isolates were whole-genome sequenced. Most C. coli water isolates (78.5%) belonged to hitherto unidentified clones when using the seven-locus sequence type (ST) scheme, while only 11.8% of the C. jejuni isolates had unidentified STs. The origin of these isolates, as defined by core-genome multi-locus sequence typing (cgMLST), was inferred by comparison with Campylobacter strain collections from meat-producing poultry, laying hens, adult cattle, veal calves, small ruminants, pigs, and wild birds. Water isolates were mainly attributed to wild birds (C. jejuni: 60.0%; C. coli: 93.7%) and meat-producing poultry (C. jejuni: 18.9%; C. coli: 5.6%). Wild bird contribution was high among isolates from recreational waters and WWTP discharge points, and in areas with low poultry (C. coli) or high ruminant (C. jejuni) densities. The contribution of meat-producing poultry was high in areas with high density of poultry, springtime, agricultural waters and WWTP discharge points. While wild birds and poultry were the main contributors to Campylobacter contamination in surface water, their contribution differed significantly by water type, season, and local poultry and ruminant densities.

A Comparative Exposure Assessment of Campylobacter in Ontario, Canada

To inform source attribution efforts, a comparative exposure assessment was developed to estimate the relative exposure to Campylobacter, the leading bacterial gastrointestinal disease in Canada, for 13 different transmission routes within Ontario, Canada, during the summer. Exposure was quantified with stochastic models at the population level, which incorporated measures of frequency, quantity ingested, prevalence, and concentration, using data from FoodNet Canada surveillance, the peer-reviewed and gray literature, other Ontario data, and data that were specifically collected for this study. Models were run with @Risk software using Monte Carlo simulations. The mean number of cells of Campylobacter ingested per Ontarian per day during the summer, ranked from highest to lowest is as follows: household pets, chicken, living on a farm, raw milk, visiting a farm, recreational water, beef, drinking water, pork, vegetables, seafood, petting zoos, and fruits. The study results identify knowledge gaps for some transmission routes, and indicate that some transmission routes for Campylobacter are underestimated in the current literature, such as household pets and raw milk. Many data gaps were identified for future data collection consideration, especially for the concentration of Campylobacter in all transmission routes.

An Improved Culture Method for Selective Isolation of Campylobacter jejuni from Wastewater

Campylobacter jejuni is one of the leading foodborne pathogens worldwide. C. jejuni is isolated from a wide range of foods, domestic animals, wildlife, and environmental sources. The currently available culture-based isolation methods are not highly effective for wastewater samples due to the low number of C. jejuni in the midst of competing bacteria. To detect and isolate C. jejuni from wastewater samples, in this study, we evaluated a few different enrichment conditions using five different antibiotics (i.e., cefoperazone, vancomycin, trimethoprim, polymyxin B, and rifampicin), to which C. jejuni is intrinsically resistant. The selectivity of each enrichment condition was measured with C_t value using quantitative real-time PCR, and multiplex PCR to determine Campylobacter species. In addition, the efficacy of Campylobacter isolation on different culture media after selective enrichment was examined by growing on Bolton and Preston agar plates. The addition of polymyxin B, rifampicin, or both to the Bolton selective supplements enhanced the selective isolation of C. jejuni. The results of 16S rDNA sequencing also revealed that Enterococcus spp. and Pseudomonas aeruginosa are major competing bacteria in the enrichment conditions. Although it is known to be difficult to isolate Campylobacter from samples with heavy contamination, this study well exhibited that the manipulation of antibiotic selective pressure improves the isolation efficiency of fastidious Campylobacter from wastewater.

A Systematic Review and Meta-Analysis of the Campylobacter spp. Prevalence and Concentration in Household Pets and Petting Zoo Animals for Use in Exposure Assessments

Animal contact is a potential transmission route for campylobacteriosis, and both domestic household pet and petting zoo exposures have been identified as potential sources of exposure. Research has typically focussed on the prevalence, concentration, and transmission of zoonoses from farm animals to humans, yet there are gaps in our understanding of these factors among animals in contact with the public who don’t live on or visit farms. This study aims to quantify, through a systematic review and meta-analysis, the prevalence and concentration of Campylobacter carriage in household pets and petting zoo animals. Four databases were accessed for the systematic review (PubMed, CAB direct, ProQuest, and Web of Science) for papers published in English from 1992–2012, and studies were included if they examined the animal population of interest, assessed prevalence or concentration with fecal, hair coat, oral, or urine exposure routes (although only articles that examined fecal routes were found), and if the research was based in Canada, USA, Europe, Australia, and New Zealand. Studies were reviewed for qualitative synthesis and meta-analysis by two reviewers, compiled into a database, and relevant studies were used to create a weighted mean prevalence value. There were insufficient data to run a meta-analysis of concentration values, a noted study limitation. The mean prevalence of Campylobacter in petting zoo animals is 6.5% based on 7 studies, and in household pets the mean is 24.7% based on 34 studies. Our estimated concentration values were: 7.65x10³cfu/g for petting zoo animals, and 2.9x10⁵cfu/g for household pets. These results indicate that Campylobacter prevalence and concentration are lower in petting zoo animals compared with household pets and that both of these animal sources have a lower prevalence compared with farm animals that do not come into contact with the public. There is a lack of studies on Campylobacter in petting zoos and/or fair animals in Canada and abroad. Within this literature, knowledge gaps were identified, and include: a lack of concentration data reported in the literature for Campylobacter spp. in animal feces, a distinction between ill and diarrheic pets in the reported studies, noted differences in shedding and concentrations for various subtypes of Campylobacter, and consistent reporting between studies.

Environmental monitoring of waterborne Campylobacter: evaluation of the Australian standard and a hybrid extraction-free MPN-PCR method

Campylobacter is the leading agent of diarrheal disease worldwide. This study evaluates a novel culture-PCR hybrid (MPN-PCR) assay for the rapid enumeration of Campylobacter spp. from estuarine and wastewater systems. To first evaluate the current, culture-based, Australian standard, an inter-laboratory study was conducted on 69 subsampled water samples. The proposed Most-Probable Number (MPN)-PCR method was then evaluated, by analysing 147 estuarine samples collected over a 2 year period. Data for 14 different biological, hydrological and climatic parameters were also collated to identify pathogen-environment relationships and assess the potential for method specific bias. The results demonstrated that the intra-laboratory performance of the MPN-PCR was superior to that of AS/NZS (σ = 0.7912, P < 0.001; κ = 0.701, P < 0.001) with an overall diagnostic accuracy of ~94%. Furthermore, the analysis of both MPN-PCR and AS/NZS identified the potential for the introduction of method specific bias during assessment of the effects of environmental parameters on Campylobacter spp. numbers.

Effects of climate change on the persistence and dispersal of foodborne bacterial pathogens in the outdoor environment: A review

According to the Intergovernmental Panel on Climate Change (IPCC), warming of the climate system is unequivocal. Over the coming century, warming trends such as increased duration and frequency of heat waves and hot extremes are expected in some areas, as well as increased intensity of some storm systems. Climate-induced trends will impact the persistence and dispersal of foodborne pathogens in myriad ways, especially for environmentally ubiquitous and/or zoonotic microorganisms. Animal hosts of foodborne pathogens are also expected to be impacted by climate change through the introduction of increased physiological stress and, in some cases, altered geographic ranges and seasonality. This review article examines the effects of climatic factors, such as temperature, rainfall, drought and wind, on the environmental dispersal and persistence of bacterial foodborne pathogens, namely, Bacillus cereus, Brucella, Campylobacter, Clostridium, Escherichia coli, Listeria monocytogenes, Salmonella, Staphylococcus aureus, Vibrio and Yersinia enterocolitica. These relationships are then used to predict how future climatic changes will impact the activity of these microorganisms in the outdoor environment and associated food safety issues. The development of predictive models that quantify these complex relationships will also be discussed, as well as the potential impacts of climate change on transmission of foodborne disease from animal hosts.

Isolation of Campylobacter sp in surface waters of Taiwan

BACKGROUND

Campylobacter sp is one of the main causes of human acute enteritis and diarrhea. It is commonly found in bird intestinal canal and pollutes water bodies through bird droppings. Clinically, detection of Campylobacter sp is by culture method and most are fecal samples. The objective of this study is to investigate the distribution of Campylobacter sp in river water of Taiwan.

METHODS

The detection of campylobacters in water by the United Kingdom Health Protection Agency was adopted and simplified. Water samples (1L) were enriched through membrane filters and selective enrichment Bolton broth. The mCCDA medium was used for culturing Campylobacter sp. In addition to using the selective media, DNA sequencing for species' identification was also included in this study.

RESULTS

Campylobacter sp was detected in only 2 of 75 water samples, and 72 suspected strains were isolated from the selective mCCDA medium, in which several pathogenic bacteria included Escherichia coli O157.

CONCLUSIONS

Not only there was pollution of Campylobacter sp in water environment but also other antibiotics-resistant pathogenic bacteria, which may cause public health risk.

Temperature-dependent FlgM/FliA complex formation regulates Campylobacter jejuni flagella length

Regulation of the biosynthesis of the flagellar filament in bacteria containing multiple flagellin genes is not well understood. The major food-borne pathogen Campylobacter jejuni possesses on both poles a flagellum that consists of two different flagellin subunits, FlaA and FlaB. Here we identify the protein Cj1464 as a regulator of C. jejuni flagellin biosynthesis. The protein shares characteristics of the FlgM family of anti-sigma factor proteins: it represses transcription of sigma(28)-dependent genes, forms a complex with sigma factor FliA, and is secreted through the flagellar filament. However, unlike other FlgM proteins, the interaction of C. jejuni FlgM with FliA is regulated by temperature and the protein does not inhibit FliA activity during the formation of the hook-basal body complex (HBB). Instead, C. jejuni FlgM limits the length of the flagellar filament by suppressing the synthesis of both the sigma(28)- and the sigma(54)-dependent flagellins. The main function of the C. jejuni FlgM therefore is not to silence sigma(28)-dependent genes until the HBB is completed, but to prevent unlimited elongation of the flagellum, which otherwise leads to reduced bacterial motility.

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

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

Investigation of food and environmental exposures relating to the epidemiology of Campylobacter coli in humans in Northwest England

This study uses multilocus sequence typing (MLST) to investigate the epidemiology of Campylobacter coli in a continuous study of a population in Northwest England. All cases of Campylobacter identified in four Local Authorities (government administrative boundaries) between 2003 and 2006 were identified to species level and then typed, using MLST. Epidemiological information was collected for each of these cases, including food and recreational exposure variables, and the epidemiologies of C. jejuni and C. coli were compared using case-case methodology. Samples of surface water thought to represent possible points of exposure to the populations under study were also sampled, and campylobacters were typed with multilocus sequence typing. Patients with C. coli were more likely to be older and female than patients with C. jejuni. In logistic regression, C. coli infection was positively associated with patients eating undercooked eggs, eating out, and reporting problems with their water supply prior to illness. C. coli was less associated with consuming pork products. Most of the cases of C. coli yielded sequence types described elsewhere in both livestock and poultry, but several new sequence types were also identified in human cases and water samples. There was no overlap between types identified in humans and surface waters, and genetic analysis suggested three distinct clades but with several "intermediate" types from water that were convergent with the human clade. There is little evidence to suggest that epidemiological differences between human cases of C. coli and C. jejuni are a result of different food or behavioral exposures alone.

Functional analysis of a Campylobacter jejuni alkaline phosphatase secreted via the Tat export machinery

Bacterial alkaline phosphatases (PhoA) hydrolyse phosphate-containing substrates to provide the preferred phosphorus source inorganic phosphate (P(i)). Campylobacter jejuni does not contain a typical PhoA homologue but contains a phosphatase that is regulated by the two-component system PhosS/PhosR. Here we describe the characterization of the enzyme, its secretion pathway and its function in the bacterium's biology. Phosphatase assays showed that the enzyme utilizes exclusively phosphomonoesters as a substrate, requires Ca(2+) for its activity, and displays maximum activity at a pH of 10. Gene disruption revealed that it is the sole alkaline phosphatase in C. jejuni. The protein contained a twin-arginine motif (RR) at its N terminus, typical of substrates of the Tat secretion system. Substitution of the twin-arginine residues showed that they are essential for enzyme activity. C. jejuni genome analysis indicated the presence of four ubiquitously expressed Tat components that may form a functional Tat secretion system as well as 11 putative Tat substrates, including the alkaline phosphatase (PhoA(Cj)) and the nitrate reductase NapA. Inactivation of tatC caused defects in both PhoA(Cj) and NapA activity as well as a reduction in bacterial growth that were all restored by complementation in trans with an intact tatC copy. The atypical overall features of the PhoA(Cj) compared to Escherichia coli PhoA support the existence in prokaryotes of a separate group of Tat-dependent alkaline phosphatases, classified as the PhoX family.

Similarity of Campylobacter lari among human, animal, and water isolates in Norway

A total of 49 isolates of Campylobacter lari from human, poultry, ducks, pigs, and water were genetically characterized. The species were identified by biotyping and multiplex polymerase chain reaction (PCR). Automatic riboprints were performed with the PstI restriction enzyme and RiboPrinter. The identification of the isolates was predicted when the corresponding pattern matched one of the patterns of the DuPont identification (DUP-ID) library and was then assigned an identification number. Thirty-five (71.4%) of the isolates were given a DUP-ID number. The isolates from water and animals showed a high degree of similarity to the human strains represented by DUP-PST1-1010, DUP-PST1-1166, DUP-PST1-1178, and DUP-PST1-1081. Some profiles (i.e., DUP-PST1-2021 and DUP-PST1-1184) were found only among the human isolates. Dendrogram analysis using BioNumerics grouped isolates into three main clusters. One of those clusters contained DUP-PST1-2021, DUP-PST1-1184, and DUP-PST1-1081, which was found in both humans and ducks. A second cluster generated DUP-PST1-1010, found in both humans and poultry, and DUP-PST1-1079, found in water. The third cluster consisted of two strains, DUP-PST1-1066 and DUP-PST1-1078, originating in humans, animals, and water. Three human strains and two poultry strains were diverse and formed their own clusters and could not be assigned a DUP-ID number. Because of the similarity of C. lari isolated from humans, poultry, ducks, pigs, and water, as well as the limited knowledge of environmental survival and its virulence factors, special hygienic precautions should be taken to avoid the risk of transmitting Campylobacter.

Acanthamoeba-Campylobacter coculture as a novel method for enrichment of Campylobacter species

In this study, we present a novel method to isolate and enrich low concentrations of Campylobacter pathogens. This method, Acanthamoeba-Campylobacter coculture (ACC), is based on the intracellular survival and multiplication of Campylobacter species in the free-living protozoan Acanthamoeba polyphaga. Four of the Campylobacter species relevant to humans and livestock, Campylobacter jejuni, C. coli, C. lari, and C. hyointestinalis, were effectively enriched by the coculture method, with growth rates comparable to those observed in other Campylobacter enrichment media. Studying six strains of C. jejuni isolated from different sources, we found that all of the strains could be enriched from an inoculum of fewer than 10 bacteria. The sensitivity of the ACC method was not negatively affected by the use of Campylobacter-selective antibiotics in the culture medium, but these were effective in suppressing the growth of seven different bacterial species added at a concentration of 10(4) CFU/ml of each species as deliberate contamination. The ACC method has advantages over other enrichment methods as it is not dependent on a microaerobic milieu and does not require the use of blood or other oxygen-quenching agents. Our study found the ACC method to be a promising tool for the enrichment of Campylobacter species, particularly from water samples with low bacterial concentrations.

Campylobacter jejuni multilocus sequence types in humans, northwest England, 2003-2004

MLST can be used to describe and analyze the epidemiology of campylobacteriosis in distinct human populations.

Detailed understanding of the epidemiology of Campylobacter is increasingly facilitated through use of universal and reproducible techniques for accurate strain differentiation and subtyping. Multilocus sequence typing (MLST) enables discriminatory subtyping and grouping of isolate types into genetically related clonal complexes; it also has the advantage of ease of application and repeatability. Recent studies suggest that a measure of host association may be distinguishable with this system. We describe the first continuous population-based survey to investigate the potential of MLST to resolve questions of campylobacteriosis epidemiology. We demonstrate the ability of MLST to identify variations in the epidemiology of campylobacteriosis between distinct populations and describe the distribution of key subtypes of interest.

Campylobacter in waterfowl and aquatic environments: incidence and methods of detection

Campylobacters are emerging as one of the most significant causes of human infections worldwide, and the role that waterfowl and the aquatic environment have in the spread of disease is beginning to be elucidated. On a world scale campylobacters are possibly the major cause of gastrointestinal infections. Campylobacters are common commensals in the intestinal tract of many species of wild birds, including waterfowl. They are also widely distributed in aquatic environments where their origins may include waterfowl as well as sewage effluents and agricultural runoff. Campylobacters have marked seasonal trends. In temperate aquatic environments they peak during winter, whereas spring-summer is the peak period for human infection. Campylobacter species may survive, and remain potentially pathogenic, for long periods in aquatic environments. The utility of bacterial fecal indicators in predicting the presence of campylobacters in natural waters is questionable. Viable but nonculturable Campylobacter cells may occur, but whether they have any role in the generation of outbreaks of campylobacteriosis is unclear. The routine detection of Campylobacter spp. in avian feces and environmental waters largely relies on conventional culture methods, while the recognition of a particular species or strain is based on serotyping and increasingly on molecular methods. Thus, PCR combined with selective enrichment enhances the detection of campylobacters in water and feces, while DNA sequencing facilitates recognition of particular species and strains.

The Campylobacter jejuni PhosS/PhosR operon represents a non-classical phosphate-sensitive two-component system

The bacterial pathogen Campylobacter jejuni carries several putative two-component signal transduction systems of unknown function. Here we report that the PhosS (Cj0889) and PhosR (Cj0890) proteins constitute a two-component system that is activated by phosphate limitation. Microarray analysis, real-time RT-PCR, and primer extension experiments indicated that this system regulates 12 genes (including the pstSCAB genes) present in three transcriptional units. Gel shift assays confirmed that recombinant PhosR protein bound DNA fragments containing the promoter regions upstream of these three transcriptional units. Although functionally similar, the PhosS/PhosR does not exhibit sequence homology with the classical PhoBR systems, has a different pho box (5'-GTTTCNAAAANGTTTC-3') recognized by the C. jejuni response regulator, and is not autoregulated. Because of these atypical properties, we designated the Cj0889-Cj0890 operon as the C. jejuni PhosS/PhosR system (phosphate sensor/phosphate response regulator) and the phosphate-regulated genes as the pho regulon of C. jejuni.

Recovery of thermophilic campylobacters from pond water and sediment and the problem of interference by background bacteria in enrichment culture

The aim of this study was to address problems in the determination of thermophilic campylobacters in turbid pond water and sediment. Thirty sets of three samples of pond water (volumes 10, 100, 1000 ml) or sediment (0.1, 1.0, 5.0 ml) were examined for the presence of thermophilic campylobacters. The different volumes of pond water were processed by membrane filtration followed by selective enrichment. The samples of sediment were subjected directly to selective enrichment. Presumptive isolates were confirmed by Gram stain, cell morphology, presence of oxidase and catalase, growth under microaerobic but not aerobic conditions, and PCR. Confirmed Campylobacter species were recovered only from 10 and 100 ml samples of water and from 0.1 and 1.0 ml samples of sediments. The 1000 ml samples of water and 5.0 ml samples of sediment never gave positive isolates. PCR indicated that the confirmed isolates were all either Campylobacter jejuni or C. coli. Enrichment cultures from 1000 ml filtrations contained the highest number of background bacteria. It is suggested that the processing of large volumes of turbid environmental water samples or of sediment is counterproductive and may not yield positive Campylobacter cultures. This is probably due to antagonistic effects of large numbers of background bacteria out-competing campylobacters during the enrichment stage. Pilot studies to establish appropriate volumes of pond water or sediment samples should be undertaken before routine determination of campylobacters is begun.

An ATP-binding cassette-type cysteine transporter in Campylobacter jejuni inferred from the structure of an extracytoplasmic solute receptor protein

Campylobacter jejuni is a Gram-negative food-borne pathogen associated with gastroenteritis in humans as well as cases of the autoimmune disease Guillain-Barré syndrome. C. jejuni is asaccharolytic because it lacks an active glycolytic pathway for the use of sugars as a carbon source. This suggests an increased reliance on amino acids as nutrients and indeed the genome sequence of this organism indicates the presence of a number of amino acid uptake systems. Cj0982, also known as CjaA, is a putative extracytoplasmic solute receptor for one such uptake system as well as a major surface antigen and vaccine candidate. The crystal structure of Cj0982 reveals a two-domain protein with density in the enclosed cavity between the domains that clearly defines the presence of a bound cysteine ligand. Fluorescence titration experiments were used to demonstrate that Cj0982 binds cysteine tightly and specifically with a K(d) of approximately 10(-7) M consistent with a role as a receptor for a high-affinity transporter. These data imply that Cj0982 is the binding protein component of an ABC-type cysteine transporter system and that cysteine uptake is important in the physiology of C. jejuni.

Protozoan Acanthamoeba polyphaga as a potential reservoir for Campylobacter jejuni

We showed by a laboratory experiment that four different Campylobacter jejuni strains are able to infect the protozoan Acanthamoeba polyphaga. C. jejuni cells survived for longer periods when cocultured with amoebae than when grown in culture alone. The infecting C. jejuni cells aggregated in amoebic vacuoles, in which they were seen to be actively moving. Furthermore, a resuscitation of bacterial cultures that were previously negative in culturability tests was observed after reinoculation into fresh amoeba cultures. After spontaneous rupture of the amoebae, C. jejuni could be detected by microscopy and culturability tests. Our results indicate that amoebae may serve as a nonvertebrate reservoir for C. jejuni in the environment.

Major structural differences and novel potential virulence mechanisms from the genomes of multiple campylobacter species

Sequencing and comparative genome analysis of four strains of Campylobacter including C. lari RM2100, C. upsaliensis RM3195, and C. coli RM2228 has revealed major structural differences that are associated with the insertion of phage- and plasmid-like genomic islands, as well as major variations in the lipooligosaccharide complex. Poly G tracts are longer, are greater in number, and show greater variability in C. upsaliensis than in the other species. Many genes involved in host colonization, including racR/S, cadF, cdt, ciaB, and flagellin genes, are conserved across the species, but variations that appear to be species specific are evident for a lipooligosaccharide locus, a capsular (extracellular) polysaccharide locus, and a novel Campylobacter putative licABCD virulence locus. The strains also vary in their metabolic profiles, as well as their resistance profiles to a range of antibiotics. It is evident that the newly identified hypothetical and conserved hypothetical proteins, as well as uncharacterized two-component regulatory systems and membrane proteins, may hold additional significant information on the major differences in virulence among the species, as well as the specificity of the strains for particular hosts.

Irrigation water as source of foodborne pathogens on fruit and vegetables

Awareness is growing that fresh or minimally processed fruit and vegetables can be sources of disease-causing bacteria, viruses, protozoa, and helminths. Irrigation with poor-quality water is one way that fruit and vegetables can become contaminated with foodborne pathogens. Groundwater, surface water, and human wastewater are commonly used for irrigation. The risk of disease transmission from pathogenic microorganisms present in irrigation water is influenced by the level of contamination; the persistence of pathogens in water, in soil, and on crops; and the route of exposure. Groundwater is generally of good microbial quality, unless it is contaminated with surface runoff; human wastewater is usually of very poor microbial quality and requires extensive treatment before it can be used safely to irrigate crops; surface water is of variable microbial quality. Bacteria and protozoa tend to show the poorest survival outside a human host, whereas viruses and helminths can remain infective for months to years. Guidelines governing irrigation water quality and strategies to reduce the risk of disease transmission by foodborne pathogens in irrigation are discussed.

Risk factors associated with Campylobacter jejuni infections in Curaçao, Netherlands Antilles

A steady increase in the incidence of Guillain-Barré syndrome (GBS) with a seasonal preponderance, almost exclusively related to Campylobacter jejuni, and a rise in the incidence of laboratory-confirmed Campylobacter enteritis have been reported from Curaçao, Netherlands Antilles. We therefore investigated possible risk factors associated with diarrhea due to epidemic C. jejuni. Typing by pulsed-field gel electrophoresis identified four epidemic clones which accounted for almost 60% of the infections. One hundred six cases were included in a case-control study. Infections with epidemic clones were more frequently observed in specific districts in Willemstad, the capital of Curaçao. One of these clones caused infections during the rainy season only and was associated with the presence of a deep well around the house. Two out of three GBS-related C. jejuni isolates belonged to an epidemic clone. The observations presented point toward water as a possible source of Campylobacter infections.