Arcobacter spp in food: isolation, identification and control

Isolation and Virulence Gene Profiling of Arcobacter spp. from Seafood and Its Environment

Arcobacter spp. are emerging microaerophilic human pathogens associated with food-borne outbreaks worldwide. The present study reports the incidence and virulence gene characterization of Arcobacter spp. from seafood. Using the selective isolation method, a total of 112 arcobacters were isolated from 43 samples out of the 123 samples screened, comprising 71 finfish, 29 crustaceans, 13 molluscan and 10 water samples. The overall incidence of Arcobacter spp. was 34.96%, with highest in water (50%), followed by mollusca (46.15%), finfish (33.8%), and cephalopods (27.59%). The isolates were confirmed by polymerase chain reaction using Arcobacter genus and species-specific primers. Among 112 Arcobacter isolates, 62 were identified as A. butzleri, 17 as A. skirrowii, 14 as A. cryaerophilus and 19 as other arcobacters. Selected isolates (n = 52) comprising 19 A. butzleri, 17 A. skirrowii, and 14 A. cryaerophilus were screened for the presence of seven putative virulence genes, among which, ciaB was predominantly present in 94% of the isolates, whereas hecB was found absent in all test isolates. More than one virulence gene was present in 94% of the isolates screened. These findings suggest the pathogenic potential of seafood isolates of arcobacters, which further necessitates the need for detailed investigations on their molecular virulence mechanisms.

The impact of tetrodotoxin (TTX) on the gut microbiome in juvenile tiger pufferfish, Takifugu rubripes

Tetrodotoxin (TTX) is a potent neurotoxin that accumulates in Takifugu rubripes, commonly known as pufferfish, through the ingestion of TTX-bearing organisms as part of their food chain. Although researchers believe that pufferfish use TTX to relieve stress, data are not currently available on how TTX affects the gut microbiota of pufferfish. To address this gap, our study aimed to investigate whether administering TTX to fish could alter their gut microbiota and overall health under various salinity conditions, including 30.0 ppt, 8.5 ppt, and 1.7 ppt salinity, which represent full-strength, isosmotic, and low-salinity stress, respectively. We analyzed the effect of TTX ingestion on the community structure, core microbiome, and metabolic capabilities of the gut microbiome using high-throughput sequencing technologies. The predominant bacterial taxa within the gut microbiome were Firmicutes (21-85%), Campilobacterota (2.8-67%), Spirochaetota (0.5-14%), and Proteobacteria (0.7-9.8%), with Mycoplasma, uncultured Arcobacteraceae, Brevinema, Vibrio, Rubritalea, and uncultured Pirellulaceae as core genera. Our findings indicated that the impact of TTX on high-abundance genera at 30.0 ppt and 8.5 ppt salinity levels was negligible, indicating their stability and resilience to TTX ingestion. However, at 1.7 ppt, TTX-fed fish showed a significant increase in uncultured Arcobacteraceae. Furthermore, our analysis of TTX-fed fish revealed taxonomic alterations in low-abundance taxa, which altered the predicted functions of the gut microbiota at all salinity levels. These results suggest that TTX administration could cause subtle effects on the metabolic functions of gut microbial communities. Overall, our study provides insights into the complex relationship between a TTX-accumulating animal, T. rubripes, and its gut microbiota.

Comparison of 16S rDNA Next Sequencing of Microbiome Communities From Post-scalder and Post-picker Stages in Three Different Commercial Poultry Plants Processing Three Classes of Broilers

Poultry processing systems are a complex network of equipment and automation systems that require a proactive approach to monitoring in order to protect the food supply. Process oversight requires the use of multi-hurdle intervention systems to ensure that any undesirable microorganisms are reduced or eliminated by the time the carcasses are processed into final products. In the present study, whole bird carcass rinses (WBCR) collected at the post-scalder and post-picker locations from three different poultry processing facilities (Plant A: mid-weight broiler processing, B: large-weight broiler processing, C: young broiler (Cornish) processing) were subjected to next generation sequencing (NGS) and microbial quantification using direct plating methods to assess the microbial populations present during these stages of the poultry process. The quantification of aerobic plate counts (APC) and Enterobacteriaceae (EB) demonstrated that reductions for these microbial classes were not consistent between the two sampling locations for all facilities, but did not provide a clear picture of what microorganism(s) may be affecting those shifts. With the utilization of NGS, a more complete characterization of the microbial communities present including microorganisms that would not have been identified with the employed direct plating methodologies were identified. Although the foodborne pathogens typically associated with raw poultry, Salmonella and Campylobacter, were not identified, sequence analysis performed by Quantitative Insights of Microbiology Ecology (QIIME) indicated shifts of Erwinia, Serratia, and Arcobacter, which are microorganisms closely related to Salmonella and Campylobacter. Additionally, the presence of Chryseobacterium and Pseudomonas at both sampling locations and at all three facilities provides evidence that these microorganisms could potentially be utilized to assess the performance of multi-hurdle intervention systems.

Draft Genome Sequences of Two Chemosynthetic Arcobacter Strains Isolated from Hydraulically Fractured Wells in Marcellus and Utica Shales

Genome sequences were obtained for two isolates of the genus Arcobacter from saline fluids produced from hydraulically fractured shale gas wells in the Marcellus and Utica formations. These genomes provide insight into microbial sulfur cycles occurring in a high-salt deep terrestrial shale environment.

Arcobacter: an emerging food-borne zoonotic pathogen, its public health concerns and advances in diagnosis and control - a comprehensive review

Arcobacter has emerged as an important food-borne zoonotic pathogen, causing sometimes serious infections in humans and animals. Newer species of Arcobacter are being incessantly emerging (presently 25 species have been identified) with novel information on the evolutionary mechanisms and genetic diversity among different Arcobacter species. These have been reported from chickens, domestic animals (cattle, pigs, sheep, horses, dogs), reptiles (lizards, snakes and chelonians), meat (poultry, pork, goat, lamb, beef, rabbit), vegetables and from humans in different countries. Arcobacters are implicated as causative agents of diarrhea, mastitis and abortion in animals, while causing bacteremia, endocarditis, peritonitis, gastroenteritis and diarrhea in humans. Three species including A. butzleri, A. cryaerophilus and A. skirrowii are predominantly associated with clinical conditions. Arcobacters are primarily transmitted through contaminated food and water sources. Identification of Arcobacter by biochemical tests is difficult and isolation remains the gold standard method. Current diagnostic advances have provided various molecular methods for efficient detection and differentiation of the Arcobacters at genus and species level. To overcome the emerging antibiotic resistance problem there is an essential need to explore the potential of novel and alternative therapies. Strengthening of the diagnostic aspects is also suggested as in most cases Arcobacters goes unnoticed and hence the exact epidemiological status remains uncertain. This review updates the current knowledge and many aspects of this important food-borne pathogen, namely etiology, evolution and emergence, genetic diversity, epidemiology, the disease in animals and humans, public health concerns, and advances in its diagnosis, prevention and control.

High Prevalence of Hyper-Aerotolerant Campylobacter jejuni in Retail Poultry with Potential Implication in Human Infection

Campylobacter jejuni is a leading cause of foodborne illnesses around the world. Since C. jejuni is microaerophilic and sensitive to oxygen, aerotolerance is important in the transmission of C. jejuni to humans via foods under aerobic conditions. In this study, 70 C. jejuni strains were isolated from retail raw chicken meats and were subject to multilocus sequence typing (MLST) analysis. In the aerotolerance testing by aerobic shaking at 200 rpm, 50 (71.4%) isolates survived after 12 h (i.e., aerotolerant), whereas 20 (28.6%) isolates did not (i.e., aerosensitive). Interestingly, further aerobic cultivation showed that 25 (35.7%) isolates still survived even after 24 h of vigorous aerobic shaking (i.e., hyper-aerotolerant). Compared to aerosensitive strains, the hyper-aerotolerant strains exhibited increased resistance to oxidative stress, both peroxide and superoxide. A mutation of ahpC in hyper-aerotolerant strains significantly impaired aerotolerance, indicating oxidative stress defense plays an important role in hyper-aerotolerance. The aerotolerant and hyper-aerotolerant strains were primarily classified into MLST clonal complexes (CCs)-21 and -45, which are known to be the major CCs implicated in human gastroenteritis. Compared to the aerosensitive strains, CC-21 was more dominant than CC-45 in aerotolerant and hyper-aerotolerant strains. The findings in this study revealed that hyper-aerotolerant C. jejuni is highly prevalent in raw chicken meats. The enhanced aerotolerance in C. jejuni would impact human infection by increasing possibilities of the foodborne transmission of C. jejuni under aerobic conditions.

Multiplex polymerase chain reaction using ethidium monoazide and propidium monoazide for distinguishing viable and dead cells of arcobacters in biofilm

This paper concerns the formation of biofilm in bacteria of the genus Arcobacter. A multiplex polymerase chain reaction (PCR) method was introduced and optimized for detecting biofilm while using the intercalating dyes ethidium monoazide (EMA) and propidium monoazide (PMA), first for analysis of strains of the genus Arcobacter from a collection, and then applied to samples of prepared biofilms. The results of the study indicate considerable variability among species of bacteria within the genus Arcobacter. The EMA–PMA PCR method can distinguish viable cells from dead cells and is therefore suitable for determining the viability of cells.

Faecal shedding of Arcobacter species following experimental infection in rats: Public health implications

Arcobacter spp. are emerging food borne pathogens associated with prolonged diarrhea and occasional systemic infections such as bactereamia and peritonitis in humans. Information on faecal shedding patterns to assess the potential role they play within the intestine however, is lacking. This study was designed to investigate faecal shedding of local isolates of Arcobacter spp. Using real time PCR for confirmation, A. cryaerophilus and A. butzleri were isolated from the stool of healthy chickens. Pathogenicity of the organisms was tested by administering a single oral challenge of 102–109 cfu/ml to 45 healthy adult male albino rats divided equally among 5 groups. Uninfected rats were used as the control group. A. cryaerophilus and A. butzleri produced infection in 100% of the animals. Experimental infection was dose dependent and caused diarrheal illness and faecal shedding was noted up to 5 weeks post infection. The present study demonstrates that rats can act as a reservoir and potential source of Arcobacter infection in humans and animals exposed to this pathogen.

Prevalence of Arcobacter species in market-weight commercial turkeys

The prevalence of Arcobacter in live market weight turkeys was determined for six Midwestern commercial flocks at three intervals. Samples (n = 987) were collected from cloaca, feathers, ceca, crop, drinkers and environmental samples on farms and from carcasses at slaughter. Initially, EMJH-P80 and CVA isolated Arcobacter from 7.1% (40 of 564) of samples, while Arcobacter enrichment broth and selective agar recovered the microbe in 4.7% of samples (23 of 489 samples). Although EMJH-P80 coupled with CVA yielded Arcobacter more frequently, the selectivity of the modified Arcobacter agar enhanced the recognition of Arcobacter colonies. A multiplex PCR was used to identify all Arcobacter species and to differentiate Arcobacter butzleri. The low prevalence of Arcobacter detected in cloacal swab (2.0%, 6 of 298 samples) and cecal contents (2.1%, 3 of 145 samples) suggests that Arcobacter infrequently colonizes the intestinal tract. Despite its low prevalence in live turkeys, Arcobacter spp. were identified in 93% of carcass swabs (139 of 150 samples). The overall prevalence of Arcobacter in drinker water decreased from 67% (31 of 46 samples) in the summer of 2003 to 24.7% (18 of 73 samples) during resampling in the spring of 2004 and was inversely related to the chlorination level.

Methodological Quality Assessment of Review Articles Evaluating Interventions to Improve Microbial Food Safety

Review articles are a means of summarizing the potentially vast volume of research on a topic. However, the methodological quality of review articles varies, and reviews on the same topic may reach different conclusions. We evaluated 65 review articles published between 2000 and 2005 that addressed the effectiveness of microbial food safety interventions, using criteria for methodological soundness developed in the medical field. Overall, the methodological quality of the review articles was poor, with none of the reviews providing information on the method of locating primary research studies or the inclusion/exclusion criteria for selecting primary studies. None of the reviews included a critical appraisal of the methodological quality of the primary studies. Less than half of the reviews stated a focused research question, explored possible reasons for differences in the results of primary studies, discussed the generalizability of results, or proposed directions for future research. There is a need to improve the methodological quality of review articles on microbial food safety interventions if they are to be of use in policy and decision making.

Identification of Arcobacter species using phospholipid and total fatty acid profiles

High-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) were used to analyze the phospholipids and fatty acids of four Arcobacter species (becoming routinely isolated from a wide variety of food sources, especially of animal origin) to provide information for the identification within these species. Phospholipid differences were observed in the HPLC profiles. GC-MS analysis provided a complete fatty acid composition for each arcobacter that after pattern recognition analysis allows taxonomic classification of each species.

Under the Microscope: Arcobacter

This review describes characteristics of the genus Arcobacter. Unlike its close phenotypically related neighbour Campylobacter, Arcobacter is not currently a major public health concern, but is considered as an emerging human pathogen, and is of significance towards animal health. This review focuses on the public health significance, culturing and typing, reservoirs, and antimicrobial studies of Arcobacter. Collectively, increasing knowledge in these areas will help to develop measures, which can be used to control this emerging pathogen.

Genotyping and genetic diversity of Arcobacter butzleri by amplified fragment length polymorphism (AFLP) analysis

AIMS

To investigate the potential of amplified fragment length polymorphism (AFLP) profiling for genotyping Arcobacter butzleri and to obtain further data on the genetic diversity of this organism.

METHODS AND RESULTS

Seventy-three isolates of Danish, British, Turkish, Swedish, Nigerian and North American origin from human infections, chickens, turkeys, ducks, sheep and poultry abbatoir effluent were studied by use of a protocol that involved stringent PCR amplification of fragments derived from digestion of genomic DNA with restriction enzymes BglII and Csp6I. The mean similarity value of duplicate profiles of 10 isolates was 91.15%, indicating the method to be reproducible. Numerical analysis of all 73 isolates distinguished 51 subtypes at the 91% similarity level, of which 39 comprised single strains. The remaining 34 isolates were distributed among 12 subtypes, each of which contained strains homogeneous with respect to their respective source of isolation. However, contemporaneous strains from the same source could also be distinguished.

CONCLUSIONS

AFLP profiling is an effective method for typing the genetically diverse organism A. butzleri.

SIGNIFICANCE AND IMPACT OF THE STUDY

The study represents a comprehensive analysis of the genetic diversity of A. butzleri by use of isolates from six countries spanning three continents and also shows that several distinct A. butzleri genotypes may be found in a given environment. AFLP profiling appears to have considerable potential for molecular epidemiological studies of this ubiquitous emerging pathogen that is implicated as a causative agent of both human and animal disease.

Isolation and characterisation of Arcobacter butzleri from meat

A survey was conducted to determine the prevalence of Arcobacter in ground chicken, pork, beef and lamb meats. Meat samples were enriched in Arcobacter broth (AB) containing cefoperazone, amphotericin and teicoplanin (CAT) supplement. Samples were screened for the presence of Arcobacter spp. using a multiplex polymerase chain reaction (PCR) followed by isolation on blood and selective agar. Arcobacter butzleri was the only species of Arcobacter isolated from 35% of 88 samples of ground meats. A. butzleri was more frequently isolated from poultry (73%) than pork (29%), beef (22%) or lamb (15%) samples. No significant differences were found in the isolation rates and from the different regions sampled. Isolates were characterised by pulsed-field gel electrophoresis (PFGE) using SacII, EagI and SmaI restriction endonucleases. A number of isolates with indistinguishable PFGE fingerprints were found to be epidemiologically related, which may indicate cross-contamination of common types of Arcobacter from different meat species or between meat species. The public health significance of Arcobacter in ground meat needs to be determined.