Prevalence of ten putative virulence genes in the emerging foodborne pathogen Arcobacter isolated from food products

Investigation and characterization of Aliarcobacter spp. isolated from cattle slaughterhouse in Türkiye

Aliarcobacter spp. have been isolated from numerous food products at retail and from animal carcasses and feces at slaughter. The objectives of this study were as follows: (i) to isolate Aliarcobacter species from different slaughterhouses' samples and (ii) to detect genetic diversity, antibiotic resistance, biofilm ability, and putative virulence gene profiles of the isolates. A molecular investigation of antibiotic resistance and virulence factors was also conducted using polymerase chain reaction (PCR). Among 150 samples, a total of 22 (14.6%) Aliarcobacter spp. isolates were obtained, with varying levels of antibiotic resistance observed. The genes tetO, tetW, and gyrA were detected in 0%, 31.8%, and 27.2% of the isolates, respectively. All isolates were resistant to ampicillin, rifampin, and erythromycin, while tetracycline was found to be the most effective antibiotic, with 81.8% of the isolates showing susceptibility to it. All isolates (100%) harbored more than one of the nine putative virulence genes tested, with 18.1% of isolates carrying more than three. Regarding biofilm formation, 7 (31.8%) and 4 (18.1%) isolates were found to form strong and moderate biofilms, respectively, while one (4.5%) isolate was classified as a weak biofilm producer. ERIC-PCR band patterns suggested that the isolated Aliarcobacter spp. from slaughterhouses had different sources of contamination. These findings highlight the potential risk posed by pathogenic and multidrug-resistant Aliarcobacter spp. in food and the need for control measures throughout the food chain to prevent the spread of these strains. The results indicate that foods of animal origin and cattle slaughterhouses are significant sources of antimicrobial resistant Aliarcobacter.

Foodborne and waterborne Arcobacter species exhibit a high virulent activity in Caco-2

Infection mechanisms of Arcobacter remain uncertain. This study aimed to determine whether 65 food and waterborne isolates of at least six species were able to adhere and invade Caco-2 cells; and whether this ability could be related to cadF, cj1349, ciaB, and/or hecA, specific genetic markers related to host cell adhesion and invasion. All adhered and invaded the cells, and harboured at least two virulence markers. The mean virulent activity shown by A. butzleri was superior to that of A. cryaerophilus (p < 0.05); but the mean adhesion and invasion values of A. lanthieri, A. skirrowii, and A. vitoriensis were even higher. Sewage isolates were significantly (p < 0.05) more adherent and invasive than the rest, and their associated gene content was higher (p < 0.05). For the first time, an association between cadF and hecA and a high adhesion capability was identified (p < 0.05). The results provide new data on the pathogenic potential of Arcobacter species present in food and water by highlighting the superiority of A. butzleri over A. cryarophilus; providing evidence on the virulence of minority species as A. lanthieri and A. vitoriensis; and confirming sewage as an important source of potentially more virulent arcobacters.

Pathogenicity assessment of Arcobacter butzleri isolated from Canadian agricultural surface water

BACKGROUND

Water is considered a source for the transmission of Arcobacter species to both humans and animals. This study was conducted to assess the prevalence, distribution, and pathogenicity of A. butzleri strains, which can potentially pose health risks to humans and animals. Cultures were isolated from surface waters of a mixed-use but predominately agricultural watershed in eastern Ontario, Canada. The detection of antimicrobial resistance (AMR) and virulence-associated genes (VAGs), as well as enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) assays were performed on 913 A. butzleri strains isolated from 11 agricultural sampling sites.

RESULTS

All strains were resistant to one or more antimicrobial agents, with a high rate of resistance to clindamycin (99%) and chloramphenicol (77%), followed by azithromycin (48%) and nalidixic acid (49%). However, isolates showed a significantly (p < 0.05) high rate of susceptibility to tetracycline (1%), gentamycin (2%), ciprofloxacin (4%), and erythromycin (5%). Of the eight VAGs tested, ciaB, mviN, tlyA, and pldA were detected at high frequency (> 85%) compared to irgA (25%), hecB (19%), hecA (15%), and cj1349 (12%) genes. Co-occurrence analysis showed A. butzleri strains resistant to clindamycin, chloramphenicol, nalidixic acid, and azithromycin were positive for ciaB, tlyA, mviN and pldA VAGs. ERIC-PCR fingerprint analysis revealed high genetic similarity among strains isolated from three sites, and the genotypes were significantly associated with AMR and VAGs results, which highlight their potential environmental ubiquity and potential as pathogenic.

CONCLUSIONS

The study results show that agricultural activities likely contribute to the contamination of A. butzleri in surface water. The findings underscore the importance of farm management practices in controlling the potential spread of A. butzleri and its associated health risks to humans and animals through contaminated water.

Occurrence of Aliarcobacter spp. in fresh and pre-cut vegetables of common use in San José, Costa Rica

Aliarcobacter is a Gram-negative rod that can cause disease in both animals and humans. Several studies have evidenced its presence in a wide variety of foods. Given that the number of foodborne illness outbreaks linked to the consumption of vegetables has increased worldwide and that there is a lack of information about the occurrence of Aliarcobacter spp. in these, the aim of this study was to evaluate its presence and the occurrence of virulence factors in both fresh and ready-to-eat vegetable samples. 180 vegetable samples from Costa Rica were analyzed for the presence of Aliarcobacter spp., including 90 pre-cut vegetable packages and 90 fresh vegetables. Two (2.2%) of the isolates from pre-cut vegetables and 19 (21.1%) of the isolates obtained from fresh vegetables were confirmed as Aliarcobacter spp. One of the isolates from the pre-cut vegetable samples was identified as A. butzleri. For the fresh vegetables, 11 isolates were identified as A. skirrowii, one as A. butzleri, and the 7 remaining isolates could not be identified at a species level. There is an 87.5% positivity for hecA and 93.8% for pldA, virulence genes in strains isolated from fresh produce, contrasting with an absolute absence from pre-cut vegetable-isolated strains. These results evidence the presence of Aliarcobacter on fresh and pre-cut vegetables from Costa Rica and the potential hazard it might represent for public health.

Antibiotic Resistance in Selected Emerging Bacterial Foodborne Pathogens-An Issue of Concern?

Antibiotic resistance (AR) and multidrug resistance (MDR) have been confirmed for all major foodborne pathogens: Campylobacter spp., Salmonella spp., Escherichia coli and Listeria monocytogenes. Of great concern to scientists and physicians are also reports of antibiotic-resistant emerging food pathogens-microorganisms that have not previously been linked to food contamination or were considered epidemiologically insignificant. Since the properties of foodborne pathogens are not always sufficiently recognized, the consequences of the infections are often not easily predictable, and the control of their activity is difficult. The bacteria most commonly identified as emerging foodborne pathogens include Aliarcobacter spp., Aeromonas spp., Cronobacter spp., Vibrio spp., Clostridioides difficile, Escherichia coli, Mycobacterium paratuberculosis, Salmonella enterica, Streptocccus suis, Campylobacter jejuni, Helicobacter pylori, Listeria monocytogenes and Yersinia enterocolitica. The results of our analysis confirm antibiotic resistance and multidrug resistance among the mentioned species. Among the antibiotics whose effectiveness is steadily declining due to expanding resistance among bacteria isolated from food are β-lactams, sulfonamides, tetracyclines and fluoroquinolones. Continuous and thorough monitoring of strains isolated from food is necessary to characterize the existing mechanisms of resistance. In our opinion, this review shows the scale of the problem of microbes related to health, which should not be underestimated.

Transcriptome Analysis of Arcobacter butzleri Infection in a Mucus-Producing Human Intestinal In Vitro Model

Arcobacter butzleri is a foodborne pathogen belonging to the Arcobacteraceae family. This Gram-negative bacterium is found in water, food, and various organisms, including farm animals, clams, and fish. Moreover, A. butzleri has been isolated from human stool samples, where it was associated with gastrointestinal symptoms such as diarrhea. The present study focused on the transcriptome analysis of three A. butzleri strains isolated from human stools and displaying variable virulence potential in vitro. We used a mucus-producing human intestinal in vitro model (Caco-2/HT29-MTX-E12) to study the colonization and invasion abilities of the three A. butzleri strains. The ability of all three A. butzleri strains to colonize our in vitro model system was subsequently confirmed. Moreover, transcriptomics showed the upregulation of putative virulence genes. Among these genes, tonB, exbB, and exbD, which belong to the same operon, were upregulated in strain LMG 11119, which also had the greatest colonization ability. Moreover, genes not currently considered A. butzleri virulence genes were differentially expressed during cell model colonization. The main functions of these genes were linked to organic acid metabolism and iron transport and particularly to the function of the TonB complex. IMPORTANCE Recent advancements in the genomic characterization of A. butzleri revealed putative virulence genes and highlighted the possible pathogenic mechanisms used by this foodborne pathogen. It is therefore possible to study the transcriptomes of these bacteria to explore possible virulence mechanisms under conditions that mimic the infection process. The transcriptome and colonization/invasion analyses that we performed in this study enabled the evaluation of A. butzleri-mediated infection of the mucus-producing human intestinal in vitro model. We confirmed the upregulation of previously proposed virulence genes in the A. butzleri strains. In addition, we identified the differential expression of a number of other genes, which are not currently thought to be associated with virulence, in three A. butzleri strains during infection of mucus-producing human epithelial cells. Changes in the concentration of acetic acid and the upregulation of genes associated with organic acid metabolism during host-pathogen contact were also observed. These findings highlight the importance of previously unreported genes in the virulence mechanisms of A. butzleri.

Profile of Aliarcobacter spp. from edible giblets: Genetic diversity, antibiotic resistance, biofilm formation

Aliarcobacter spp. are recognized as emerging foodborne pathogens and consumption of foods contaminated with them can be a hazard to human and animal health. This study was conducted to investigate the prevalence of Aliarcobacter spp. in edible internal organs of different animal species from retail markets and giblet sellers. Additionally, this study was focused on the antimicrobial resistance, virulence profiles, biofilm-forming capabilities, and phylogenetic relationships of obtained isolates. A total of 270 samples were analyzed from which, 28 (10.4 %) were isolated as Aliarcobacter spp. by conventional methods. Within the 28 Aliarcobacter spp. isolates, 17 (60.7 %) were identified as A. butzleri, 10 (35.7 %) were A. cryaerophilus and one (3.5 %) was A. skirrowii by PCR method. The disc diffusion method showed that the highest resistance rate of Aliarcobacter spp. was seen against oxacillin (78.5 %), and 20 (71.4 %) out of the 28 isolates exhibited multidrug resistance (MDR). Out of the 28 isolates, mviN, pldA, tlyA, and hecB virulence genes were detected in 85.7 %, 46.4 %, 46.4 %, and 3.5 %, respectively, but irgA, Cj1349, ciaB, cadF, and hecA genes were not detected. According to the microplate test, 27 (96.4 %) isolates had weak biofilm ability while one A. cryaerophilus isolate (3.6 %) exhibited strong biofilm formation. ERIC-PCR band patterns suggested that isolated Aliarcobacter spp. from giblets, have different contamination sources. The presence of pathogenic and multidrug-resistant Aliarcobacter spp. in food poses a potential risk to public health and control measures throughout the food chain are necessary to prevent the spread of these strains.

Species classification and novel plasmid identifications in Arcobacter cryaerophilus and Arcobacter cryaerophilus-like organisms

The Arcobacter is a globally emerging foodborne and zoonotic pathogen that can cause diarrhea in humans. It is relatively homogenous and clearly distinguishes the group from other Epsilonproteobacteria. Arcobacter cryaerophilus (A. cryaerophilus) is a heterogeneous species and little is known about its genomic characterization in China. This study aims to determine the genetic and plasmid features of A. cryaerophilus based on whole-genome sequence (WGS). Average Nucleotide Identity (ANI) and in silico DNA–DNA hybridization (isDDH) were used for the species classification for 90 initially identified A. cryaerophilus strains. One complete genome and 42 draft genomes were obtained by whole genome sequencing. The genomic characteristics were determined using various bioinformatics software. The genomes of the strains examined were estimated to vary from 1.81 to 2.28 Mb in length, with a G + C content of around 27%. ANI and isDDH results indicated that 90 initially identified A. cryaerophilus strains should be reclassified into four new species (ANI > 96% or isDDH > 70%). Two clades (four subclades) were identified among 90 genomes with the phylogenetic analysis. The phylogenetic tree indicated these 90 genomes exhibited a high intra-species genomic diversity. No clustering was assorted with the host or geographic location among these genomes. Aminoglycoside resistance genes, such as aph(2’’)-Ih, AAC(6’)-Ie-APH(2’’)-Ia, aac(6’)-IIa, ant(6), and streptothricin resistance gene SAT-4 were detected in the chromosomes from a third of the Chinese strains. Virulence-related genes were identified in all the sequenced strains. A novel large multiple drug-resistant plasmid (named pCNAC48 with 161,992 bp in length) was identified in strain ICDCAC48. Two antibiotic-resistance islands were found in the plasmid with lengths of 7,950 and 25,137 bp and G + C content of 38.23 and 32.39%, respectively. The drug resistance genes and some transposable elements were cross-distributed among the islands in the plasmid. Antimicrobial susceptibility tests indicated these resistance genes in the plasmid were functional. Plasmid conjugation and curing experiments proved pCNAC48 was stable in strain ICDCAC48. It was the first identified multiple drug resistance plasmid in A. cryaerophilus-like.

Comparative genomics analysis and virulence-related factors in novel Aliarcobacter faecis and Aliarcobacter lanthieri species identified as potential opportunistic pathogens

Background

Emerging pathogenic bacteria are an increasing threat to public health. Two recently described species of the genus Aliarcobacter, A. faecis and A. lanthieri, isolated from human or livestock feces, are closely related to Aliarcobacter zoonotic pathogens (A. cryaerophilus, A. skirrowii, and A. butzleri). In this study, comparative genomics analysis was carried out to examine the virulence-related, including virulence, antibiotic, and toxin (VAT) factors in the reference strains of A. faecis and A. lanthieri that may enable them to become potentially opportunistic zoonotic pathogens.

Results

Our results showed that the genomes of the reference strains of both species have flagella genes (flaA, flaB, flgG, flhA, flhB, fliI, fliP, motA and cheY1) as motility and export apparatus, as well as genes encoding the Twin-arginine translocation (Tat) (tatA, tatB and tatC), type II (pulE and pulF) and III (fliF, fliN and ylqH) secretory pathways, allowing them to secrete proteins into the periplasm and host cells. Invasion and immune evasion genes (ciaB, iamA, mviN, pldA, irgA and fur2) are found in both species, while adherence genes (cadF and cj1349) are only found in A. lanthieri. Acid (clpB), heat (clpA and clpB), osmotic (mviN), and low-iron (irgA and fur2) stress resistance genes were observed in both species, although urease genes were not found in them. In addition, arcB, gyrA and gyrB were found in both species, mutations of which may mediate the resistance to quaternary ammonium compounds (QACs). Furthermore, 11 VAT genes including six virulence (cadF, ciaB, irgA, mviN, pldA, and tlyA), two antibiotic resistance [tet(O) and tet(W)] and three cytolethal distending toxin (cdtA, cdtB, and cdtC) genes were validated with the PCR assays. A. lanthieri tested positive for all 11 VAT genes. By contrast, A. faecis showed positive for ten genes except for cdtB because no PCR assay for this gene was available for this species.

Conclusions

The identification of the virulence, antibiotic-resistance, and toxin genes in the genomes of A. faecis and A. lanthieri reference strains through comparative genomics analysis and PCR assays highlighted the potential zoonotic pathogenicity of these two species. However, it is necessary to extend this study to include more clinical and environmental strains to explore inter-species and strain-level genetic variations in virulence-related genes and assess their potential to be opportunistic pathogens for animals and humans.

NRJ Media as the Gold-Standard Arcobacter-Specific Detection System: Applications in Poultry Testing

Arcobacter species are ubiquitous emerging pathogens with an impact that has been underestimated due to limitations in isolation and detection methods. Our group recently developed the novel NRJ Arcobacter-detection system, with major improvements in specificity and selectivity compared to other culture-based methods. In this work, the NRJ detection system was evaluated using retail whole broiler chicken carcass. Nanopore 16S rRNA gene amplicon sequencing demonstrated that Arcobacter species are found in very low abundance in retail chicken and that indigenous microbiota could be a major factor interfering with detection. Comparison of the microbiome obtained from modified Houf broth (HB) method, as the standard detection system, and the novel NRJ method, showed Arcobacter abundances of <15% and >97%, respectively. The NRJ system significantly inhibits the growth of non-target microbiota, and specifically allows the multiplication of Arcobacter species. In this report, we describe the gold-standard of Arcobacter-specific culture-based method to test food matrices, which can be used for other applications, such as clinical and environmental sampling.

Genotyping, antibiotic resistance and prevalence of Arcobacter species in milk and dairy products

BACKGROUND

Arcobacter spp. has been considered an emerging foodborne pathogen and a hazard to human health. The dairy chain has been isolated from different sources; nevertheless, data on Arcobacter occurrence in raw milk and dairy products in Iran are still scant.

OBJECTIVE

The present study investigates the prevalence, antimicrobial susceptibility and the presence of virulence genes of Arcobacters species isolated from milk and dairy products.

METHODS

Then, a total of 350 raw milk samples and 400 dairy product samples were collected from dairy supply centers in Isfahan, Iran. Presumptive Arcobacter strains were obtained by enriching samples in Oxoid Arcobacter enrichment broth (AEB) followed by the filtration of enrichment product through 0.45-μm pore size membrane filters laid onto non-selective blood at 30°C under microaerophilic conditions. Molecular identification of Arcobacter cryaerophilus and A. butzleri was performed by Polymerase chain reaction (PCR) amplification of the 16S rRNA gene, followed by sequencing. The disc diffusion method was used to determine the antimicrobial susceptibility of isolates. Targeted resistance and virulence genes were detected using multiplex PCR.

RESULTS

The results show a low recovery rate of Arcobacter spp. in milk. Arcobacters were found in all types of milk, except raw camel milk, but were absent from all dairy products. Arcobacter butzleri was the predominant species in raw milk. Detection of virulence genes shows that all virulence genes targeted were found among A. butzleri, and six (cadF, cj1349, irgA, mviN, pldA, tlyA) were found among A. cryaerophilus. All A. butzleri strains and some A. cryaerophilus strains isolated from milk were resistant to amoxicillin-clavulanic acid and tetracycline. All A. cryaerophilus isolates from milk were susceptible to gentamycin, streptomycin, erythromycin and ciprofloxacin. The distribution of resistance genes in Arcobacter strains in milk shows that all isolates carried tet(O) and bla_OXA-61 genes.

CONCLUSIONS

In conclusion, the results indicate a low recovery rate of Arcobacter spp. in milk and milk products. However, a significant number of Arcobacter strains with putative virulence genes may be potential pathogens for humans and an overall increase in Arcobacter resistance to first-line antibiotics. These results highlight the need for regular surveillance of Arcobacter strains in milk and milk products in Iran.

Prevalence, antimicrobial susceptibility and virulence gene profiles of Arcobacter species isolated from human stool samples, foods of animal origin, ready-to-eat salad mixes and environmental water

Background

Members of the genus Arcobacter are considered as emerging zoonotic food and waterborne pathogens that cause gastroenteritis and bacteremia in humans. However, the potential risk that Arcobacter species pose to public health remains unassessed in various countries, including Baltic states. Therefore, the aim of this study was to determine the prevalence, antimicrobial susceptibility and presence of putative virulence genes of Arcobacter isolates recovered from humans, food products and environmental water in Lithuania.

Results

A total of 1862 samples were collected and examined from 2018 to 2020 in the city of Kaunas. Overall, 11.2% (n = 208) of the samples were positive for the presence of Arcobacter spp. The highest prevalence was detected in chicken meat (36%), followed by environmental water (28.1%), raw cow milk (25%), ready-to-eat salad mixes (7.1%) and human stool (1.7%). A. butzleri was the most frequently isolated species (n = 192; 92.3%), followed by A. cryaerophilus (n = 16; 7.7%). Arcobacter spp. antimicrobial susceptibility testing revealed unimodally distributed aggregated minimal inhibitory concentrations (MICs) for gentamicin, tetracycline, ciprofloxacin, ampicillin and erythromycin. However, a bimodal distribution for azithromycin was found with 96.2% of determined MICs above the epidemiological cut-off value (ECOFF) defined for Campylobacter jejuni (0.25 µg/ml). Majority of the Arcobacter isolates (n = 187; 89.9%) showed high susceptibility to ciprofloxacin with MICs below or equal to the ECOFF value of 0.5 µg/ml. The putative virulence genes cadF (100%), ciaB (100%), cj1349 (99%), tlyA (99%), mviN (97.9%) and pldA (95.8%) were the predominant genes detected among A. butzleri isolates. In contrast, the mviN and ciaB genes were present in all, whereas cj1349 (12.5%), tlyA (25%) and hecA (12.5%) were only detected in few A. cryaerophilus isolates.

Conclusions

Our results demonstrate that food products and environmental water in Lithuania are frequently contaminated with Arcobacter spp. that carry multiple putative virulence genes. Furthermore, A. butzleri were isolated from 1.7% of inpatients. Fluoroquinolones and aminoglycosides were found to be more effective against Arcobacter in comparison to other antimicrobial agents. However, further studies are needed to determine the pathogenic mechanisms and factors that facilitate the spread of Arcobacter infections.

Functional pangenome analysis reveals high virulence plasticity of Aliarcobacter butzleri and affinity to human mucus

Aliarcobacter butzleri is an emerging pathogen that may cause enteritis in humans, however, the incidence of disease caused by this member of the Campylobacteriaceae family is still underestimated. Furthermore, little is known about the precise virulence mechanism and behavior during infection. Therefore, in the present study, through complementary use of comparative genomics and physiological tests on human gut models, we sought to elucidate the genetic background of a set of 32 A. butzleri strains of diverse origin and to explore the correlation with the ability to colonize and invade human intestinal cells in vitro. The simulated infection of human intestinal models showed a higher colonization rate in presence of mucus-producing cells. For some strains, human mucus significantly improved the resistance to physical removal from the in vitro mucosa, while short time-frame growth was even observed. Pangenome analysis highlighted a hypervariable accessory genome, not strictly correlated to the isolation source. Likewise, the strain phylogeny was unrelated to their shared origin, despite a certain degree of segregation was observed among strains isolated from different segments of the intestinal tract of pigs. The putative virulence genes detected in all strains were mostly encompassed in the accessory fraction of the pangenome. The LPS biosynthesis and in particular the chain glycosylation of the O-antigen is harbored in a region of high plasticity of the pangenome, which would indicate frequent horizontal gene transfer phenomena, as well as the involvement of this hypervariable structure in the adaptive behavior and sympatric evolution of A. butzleri. Results of the present study deepen the current knowledge on A. butzleri pangenome by extending the pool of genes regarded as virulence markers and provide bases to develop new diagnostic approaches for the detection of those strains with a higher virulence potential.

Contamination and Biofilm Formation of Foodborne and Opportunistic Pathogens in Yellow-Feathered Chicken Carcass

This study aims to analyze the contamination and biofilm formation of foodborne and opportunistic pathogens in yellow-feathered chicken carcasses sampled in different seasons and to prove the relationship between biofilm-forming ability and bacterial extracellular polysaccharide (EPS) production. A total of 78 strains were isolated from chicken samples. The strains consisted of 30.8% Escherichia coli, 14.1% Pseudomonas aeruginosa, 12.8% Salmonella enteritidis, 12.8% Klebsiella pnenmoniae, 10.2% Enterobacter cloacae, 8.9% Proteus mirabilis, 5.1% Klebsiella oxytoca, 1.3% Staphylococcus aureus, and 1.3% Citrobacter braakii. Crystal violet staining assay revealed six strains with strong biofilm-forming ability, namely, E. coli S7, K. oxytoca B12, K. pnenmoniae B6, S. enteritidis H4, P. aeruginosa M5, and S. aureus G1, which showed had high abilities of cell motility and EPS production. Confocal laser scanning microscopy and scanning electron microscopy showed that all six strains can form mature biofilm architectures after 5 d of cultivation. This study may serve as a reference to control the contamination of foodborne pathogens in yellow-feathered chicken and enhance the quality and shelf life of these chicken products.

Antimicrobial resistance and virulence genes profiles of Arcobacter butzleri strains isolated from back yard chickens and retail poultry meat in Chile

This research aims to investigate the presence and pathogenic potential of Arcobacter in poultry meat samples purchased in the retail market of Valdivia (South of Chile) as well as in faecal samples from backyard chickens from rural areas around this city. The isolates obtained were identified by molecular methods. Furthermore, putative virulence genes were assessed by PCR and the antimicrobial resistance was tested by phenotypic methods. Arcobacter was present in 41·6% of the samples, with the highest value in retail poultry meat (55·7%) followed by backyard production (28·0%). Arcobacter butzleri was the most prevalent species (75·6%) followed by Arcobacter skirrowii (14·8%) and Arcobacter cryaerophilus (9·6%). An 8·5% of A. butzleri strains from meat were resistant to both ciprofloxacin and tetracycline and 6·1% were resistant to erythromycin, while none was resistant to gentamycin, unlike strains from domestic chickens, which showed no resistance. Furthermore, A. butzleri strains from chicken meat presented a higher prevalence of virulence genes than strains from domestic chickens. In fact, in this last group, some genes (hecA, hecB and irgA) were completely absent. Therefore, this study provides insight on the epidemiology of Arcobacter in Chilean poultry and suggests that under traditional breeding conditions strains are, apparently, less pathogenic and drug resistant.

Highly heterogeneous temporal dynamics in the abundance and diversity of the emerging pathogens Arcobacter at an urban beach

While the significance of Arcobacter in clinical settings grows, the ecological dynamics of potentially pathogenic Arcobacter in coastal marine environments remains unclear. In this study, we monitored the temporal dynamics of Arcobacter at an urban beach subject to significant stormwater input and wet weather sewer overflows (WWSO). Weekly monitoring of bacterial communities over 24 months using 16S rRNA amplicon sequencing revealed large, intermittent peaks in the relative abundance of Arcobacter. Quantitative PCR was subsequently employed to track absolute abundance of Arcobacter 23S rRNA gene copies, revealing peaks in abundance reaching up to 10⁸ gene copies L^-1, with these increases statistically correlated with stormwater and WWSO intrusion. Notably, peaks in Arcobacter abundance were poorly correlated with enterococci plate counts, and remained elevated for one week following heavy rainfall. Using oligotyping we discriminated single nucleotide variants (SNVs) within the Arcobacter population, revealing 10 distinct clusters of SNVs that we defined as Arcobacter "ecotypes", with each displaying distinct temporal dynamics. The most abundant ecotype during stormwater and modelled WWSO events displayed 16S rRNA sequence similarity to A. cryaerophilius, a species previously implicated in human illness. Our findings highlight the diverse environmental drivers of Arcobacter abundance within coastal settings and point to a potentially important, yet overlooked exposure risk of these potential pathogens to humans.

Occurrence, virulence gene and antimicrobial susceptibility profiles of Arcobacter sp. isolated from catla (Catla catla) in India

In the present study, a total of 100 catla (Catla catla-major South Asian carp, local name botcha) collected from local fish markets and aquaculture ponds were subjected for isolation and characterization of Arcobacter sp. In all, 21 Arcobacter sp. were isolated, of which 18 (85·7%) were Arcobacter butzleri and three (14%) were A. cryoaerophilus as identified by multiplex PCR. All 18 A. butzleri isolates were positive for mviN, ciaB and tlyA virulence genes, three of A. cryoaerophilus isolates carried mviN gene and none of the isolates were positive for cadF, irgA, cj1349, hecA and hecB genes. All isolates (n = 21) were resistant to penicillin (100%). Meanwhile, 71·43, 23·81, 23·81, 14·29 and 9·52% of the isolates showed resistance towards vancomycin, nalidixic acid, erythromycin, cefixime and kanamycin, respectively. Multidrug resistance was observed in 23·81% of the Arcobacter sp. isolates and none of the isolates were positive for any of the extended spectrum beta-lactamases either by phenotypic or by molecular identification genes (bla_OXA , bla_SHV , bla_TEM , bla_CTX-M1 , bla_CTX-M2 and bla_CTX-M9 groups). The results emphasize the need to implement specific control procedures to reduce the use of antibiotics in aquaculture particularly the ones which are very important in human medicine. SIGNIFICANCE AND IMPACT OF THE STUDY: Arcobacter species are emerging food- and water-borne human pathogens. In this study, Arcobacter butzleri was predominant in fish compared to A. cryoaerohilus and A. skirrowii. Higher incidence of arcobacters in fish market samples suggests cross contamination and unhygienic handling of fish in markets. Virulence genes profile and antibiotics resistance of the Arcobacter sp. isolated in current study indicate pathogenic potential of Arcobacter sp. to humans. Occurrence of multidrug-resistant Arcobacter sp. in fish is a major concern in food safety. To our knowledge, this is the first report of Arcobacter sp. from freshwater fish, catla (Catla catla) in India.

Characterization of Arcobacter strains isolated from human stool samples: results from the prospective German prevalence study Arcopath

Background

Arcobacter constitute emerging food- and waterborne pathogens causing gastroenteritis in humans, but the underlying mechanisms are only incompletely understood. We therefore characterized Arcobacter isolates derived from human stool samples that had been collected during a prospective prevalence study in Germany in vitro. Thirty-six bacterial isolates belonging to the species A. butzleri (n = 24), A. cryaerophilus (n = 10) and A. lanthieri (n = 2) were genotyped by ERIC-PCR, the presence of 10 putative virulence genes was assessed and cytotoxic effects on the human intestinal cell line HT-29/B6 were analyzed applying the WST-assay.

Results

Genotyping revealed high genetic diversity within the species A. butzleri, A. cryaerophilus and A. lanthieri. Both, A. butzleri and A. lanthieri encoded for a large number of putative virulence genes, while fewer genes were detectable in A. cryaerophilus isolates. Notably, the three cytolethal distending toxin (CDT) genes cdtA, cdtB and cdtC were abundant in both A. lanthieri isolates. Furthermore, all A. butzleri and A. lanthieri, but only one of the A. cryaerophilus isolates exerted cytotoxic effects.

Conclusions

Our study provides evidence for the abundance of putative virulence genes in Arcobacter isolates and prominent cytotoxic effects of A. butzleri and A. lanthieri in vitro. The presence of cdtA, cdtB, cdtC in A. lanthieri points towards CDT secretion as potential mechanism underlying cytotoxicity as opposed to A. butzleri. However, the association of the Arcobacter virulence factors detected and human morbidity should be addressed in future studies.

Arcobacter spp. in raw milk from vending machines in Piedmont and occurrence of virulence genes in isolates

Arcobacter spp. has been recognized as an emerging foodborne pathogen and a hazard to human health. In the dairy chain, it has been isolated from different sources, nevertheless data on Arcobacter occurrence in raw milk provided by vending machines are few. This study aimed to identify potentially pathogenic Arcobacter spp. in raw milk intended for human consumption sold through vending machines located in Piedmont. In an 8-month period, 37 raw milk samples were collected from 24 dairy farms: 12 (32,4%) were collected directly in farm from bulk tank milk and 25 (67,6%) from vending machines. Eight (21,6%) out of the 37 milk samples and 7 (29,2%) out of the 24 dairy farms were positive for Arcobacter spp. by culture examination. Four (16%) out of the 25 samples from vending machines and 4 (33,3%) out of the 12 samples from bulk tank milk were positive. All 8 isolates were identified as A. butzleri both by MALDI-TOF MS and multiplex end-point PCR. According to the detection of virulence genes, a total of four Patho-types were highlighted: 5 isolates in P-type 1 and only one isolate for each of the P-types 2-3-4. A. butzleri isolates carrying encoding virulence factors genes were isolated from raw milk intended for human consumption: these findings strengthen the compulsory consumption after boiling as required by current legislation and suggest the need of enlarging the analytical investigations to other microorganisms not yet included in the food safety criteria.

Reduction of Arcobacter at Two Conventional Wastewater Treatment Plants in Southern Arizona, USA

This study aimed to identify the bacterial community in two wastewater treatment plants (WWTPs) and to determine the occurrence and reduction of Arcobacter, along with virulence genes (ciaB and pldA). A total of 48 samples (24 influent and 24 effluent) were collected at two WWTPs in southern Arizona in the United States, monthly from August 2011 to July 2012. Bacterial DNA extract was utilized for 16S rRNA metagenomic sequencing. Quantification of Arcobacter 16S rRNA gene was conducted using a recently developed SYBR Green-based quantitative PCR assay. Among 847 genera identified, 113 (13%) were identified as potentially pathogenic bacteria. Arcobacter 16S rRNA gene was detected in all influent samples and ten (83%) and nine (75%) effluent samples at each plant, respectively. Log reduction ratios of Arcobacter 16S rRNA gene in Plant A and Plant B were 1.7 ± 0.9 (n = 10) and 2.3 ± 1.5 (n = 9), respectively. The ciaB gene was detected by quantitative PCR in eleven (92%) and twelve (100%) of 12 influent samples from Plant A and Plant B, respectively, while the pldA gene was detected in eight (67%) and six (50%) influent samples from Plant A and Plant B, respectively. The prevalence of potentially pathogenic bacteria in WWTP effluent indicated the need for disinfection before discharge into the environment.

Identification of 16S rRNA and Virulence-Associated Genes of Arcobacter in Water Samples in the Kathmandu Valley, Nepal

This study aimed to determine the prevalence of Arcobacter and five associated virulence genes (cadF, ciaB, mviN, pldA, and tlyA) in water samples in the Kathmandu Valley, Nepal. A total of 286 samples were collected from deep tube wells (n = 30), rivers (n = 14), a pond (n = 1), shallow dug wells (n = 166), shallow tube wells (n = 33), springs (n = 21), and stone spouts (n = 21) in February and March (dry season) and August (wet season), 2016. Bacterial DNA was extracted from the water samples and subjected to SYBR Green-based quantitative PCR for 16S rRNA and virulence genes of Arcobacter. The 16S rRNA gene of Arcobacter was detected in 36% (40/112) of samples collected in the dry season, at concentrations ranging from 5.7 to 10.2 log copies/100 mL, and 34% (59/174) of samples collected in the wet season, at concentrations of 5.4–10.8 log copies/100 mL. No significant difference in Arcobacter 16S rRNA gene-positive results was observed between samples collected in the two seasons (p > 0.05). Seventeen (17%), 84 (84%), 19 (19%), 23 (23%), and 17 (17%) of the 99 Arcobacter 16S rRNA gene-positive samples were also positive for cadF, ciaB, mviN, pldA, and tlyA, respectively. At least one virulence gene was detected in 87 (88%) of the 99 Arcobacter 16S rRNA gene-positive samples. The presence of Arcobacter and the virulence genes in these samples illustrates the persistence of pathogenic bacteria in the environment and highlights the importance of regular monitoring of water for pathogens.

Identification of virulence and antibiotic resistance factors in Arcobacter butzleri isolated from bovine milk by Whole Genome Sequencing

Arcobacter butzleri is a pathogenic aerobic bacterium responsible for diarrhea and septicemia in humans. It is frequently isolated from food products of animal origin, including milk and dairy products. To data, few reports are currently available on the genetic characteristics and virulence profiles of A. butzleri. The aim of this study was to investigate the genetic diversity and to characterize the virulence and antibiotic resistance profiles of 10 A. butzleri strains isolated from bovine milk samples by Whole Genome Sequence (WGS). Multi-Locus Sequence Typing (MLST) revealed that three isolates belonged to the ST66, two to the ST420 and the remaining five strains to the ST627, ST629, ST630, ST633 and ST637, respectively. The 100% of the strains carried cadF, pldA, ciaB, cj1349, mviN and tlyA virulence factors genes; 60% iroE; 50% irgA; 10% hecB. Resistome prediction showed a multidrug resistance: 100% of isolates resulted resistant to fluoroquinolones and tetracycline; 90% of strains to rifampicin and cephalosporins and a minor percentage to other antibiotics. Furthermore, the 50% of strains harbored four mutations in Mycobacterium tuberculosis katG gene conferring resistance to isoniazid. The study provided interesting data on the virulence characteristics and on the genetic endowment related to the antimicrobial resistance of A. butzleri isolates from milk. The determination of the STs also added information concerning the genetic variability of this microorganism. To date, a very limited number of studies have been published on the typing of A. butzleri using WGS, so this paper proposes an innovative methodological approach that allows a rapid and complete characterization of pathogenic microorganisms.

Genomic Characterization of Arcobacter butzleri Isolated From Shellfish: Novel Insight Into Antibiotic Resistance and Virulence Determinants

Arcobacter (A.) butzleri is an emerging pathogenic microorganism, whose taxonomy has been recently suggested to be emended to the Aliarcobacter (Al.) butzleri comb. nov. Despite extensive taxonomic analysis, only few fragmented studies have investigated the occurrence and the prevalence of virulence and antibiotic resistance determinants of this species in strains isolated from shellfish. Herein we report for the first time the whole genome sequencing and genomic characterization of two A. butzleri strains isolated from shellfish, with particular reference to the antibiotic, heavy metals and virulence determinants. This study supported the taxonomic assignment of these strains to the Al. butzleri species, and allowed us to identify antibiotic and metal resistance along with virulence determinants, also additional to those previously reported for the only two A. butzleri strains from different environments genomically characterized. Moreover, both strains showed resistance to β-lactams, vanocomycin, tetracycline and erythromycin and susceptibility to aminoglycosides and ciprofloxacin. Beside enlarging the availability of genomic data to perform comparative studies aimed at correlating phenotypic differences associated with ecological niche and geographic distribution with the genetic diversity of A. butzleri spp., this study reports the endowment of antibiotic and heavy metal resistance and virulence determinants of these shellfish-isolated strains. This leads to hypothesize a relatively high virulence of A. butzleri isolated from shellfish and prompt the need for a wider genomic analysis and for in vitro and in vivo studies of more strains isolated from this and other ecological niches, to unravel the mechanism of pathogenicity of this species, and the potential risk associated to their consumption.

Novel virulence, antibiotic resistance and toxin gene-specific PCR-based assays for rapid pathogenicity assessment of Arcobacter faecis and Arcobacter lanthieri

Background

Arcobacter faecis and A. lanthieri are two newly classified species of genus Arcobacter. The prevalence and distribution of virulence, antibiotic resistance and toxin (VAT) genes in these species are required to assess their potential pathogenic health impacts to humans and animals. This study (i) developed species- and gene-specific primer pairs for the detection of six virulence, two antibiotic resistance, and three toxin genes in two target species; (ii) optimized eight single-tube multiplex and three monoplex PCR protocols using the newly developed species- and gene-specific primers; and (iii) conducted specificity and sensitivity evaluations as well as validation of eleven mono- and multiplex PCR assays by testing A. faecis (n= 29) and A. lanthieri (n= 10) strains isolated from various fecal and agricultural water sources to determine the prevalence and distribution of VAT genes and assess the degree of pathogenicity within the two species.

Results

Detection of all ten and eleven target VAT genes, and expression of cytolethal distending toxin (cdtA, cdtB and cdtC) genes in A. faecis and A. lanthieri reference strains with high frequency in field isolates suggest that they are potentially pathogenic strains. These findings indicate that these two species can pose a health risk to humans and animals.

Conclusions

The study results show that the developed mono- and multiplex PCR (mPCR) assays are simple, rapid, reliable and sensitive for the simultaneous assessment of the potential pathogenicity and antibiotic resistance profiling of tet(O) and tet(W) genes in these two newly discovered species. Also, these assays can be useful in diagnostic and analytical laboratories to determine the pathotypes and assessment of the virulence and toxin factors associated to human and animal infections.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1357-7) contains supplementary material, which is available to authorized users.

Occurrence of virulence-associated genes in Arcobacter butzleri and Arcobacter cryaerophilus isolates from foodstuff, water, and clinical samples within the Czech Republic

Bacteria of the Arcobacter (A.) genus, originating mainly from food and water, are dreaded germs for humans as well as animals. However, the virulence of these bacteria has not been fully elucidated yet. This study looked at the occurrence of eight virulence-associated factors (ciaB, cj1349, pldA, irgA, hecA, tlyA, mviN, hecB) in a total of 80 isolates of Arcobacter butzleri and 22 isolates of A. cryaerophilus. The isolates were derived from food, water, and clinical samples. A polymerase chain reaction using specific primers was used to detect these virulence-associated genes. The presence of all genes in the isolates of A. butzleri (98.8% ciaB, 95.0% cj1349, 98.8% pldA, 22.5% irgA, 31.3% hecA, 95.0% tlyA, 97.5% mviN, 38.8% hecB) and A. cryaerophilus (95.5% ciaB, 0.0% cj1349, 9.1% pldA, 0.0% irgA, 0.0% hecA, 31.8% tlyA, 90.9% mviN, 0.0% hecB) was monitored. Among the tested isolates, there were 13 isolates (12.7%) of A. butzleri, in which the presence of all eight virulence-associated genes was recorded in the genome. In contrast, in one A. cryaerophilus strain, none of the observed genes were detected. The presence of ciaB and mviN genes was significantly more frequent in A. cryaerophilus isolates than other genes (P < 0.05). In general, more virulence-associated genes have been detected in A. butzleri isolates compared to A. cryaerophilus. The most common gene combination (ciaB, cj1349, pldA, tlyA, mviN) was detected in case of 39 isolates. In 50.0% of A. butzleri isolates derived from clinical samples, all eight virulence-associated genes were significantly more frequently detected (P < 0.05). The tlyA gene occurred significantly more frequent in A. butzleri isolates from meat and water samples and irgA and hecB genes in clinical samples. Therefore, our study provides information about occurrence of virulence-associated genes in genome of Arcobacter isolates. These findings could be hazardous to human health, because the presence of virulence-associated genes is the assumption for potential dangerousness of these bacteria. Our results indicate high incidence of virulence-associated genes in Arcobacter genomes and hence potentially pathogenic properties of the studied strains.

Prevalence of Putative Virulence Genes in Campylobacter and Arcobacter Species Isolated from Poultry and Poultry By-Products in Tunisia

Campylobacter and Arcobacter spp. are common causes of gastroenteritis in humans; these infections are commonly due to undercooked poultry. However, their virulence mechanism is still poorly understood. The aim of this study was to evaluate the presence of genotypic virulence markers in Campylobacter and Arcobacter species using PCR. The prevalence of virulence and cytolethal distending toxin (CDT) genes was estimated in 71 Campylobacteraceae isolates. PCR was used to detect the presence of virulence genes (iam, cadF, virB1, flaA, cdtA, cdtB, and cdtC) using specific primers for a total of 45 Campylobacter isolates, including 37 C. jejuni and 8 C. coli. All the Campylobacter isolates were positive for the cadF gene. The plasmid gene virB11 was not detected in any strain. The invasion associated marker was not detected in C. jejuni. Lower detection rates were observed for flaA, cdtA, cdtB, and cdtC. The presence of nine putative Arcobacter virulence genes (cadF, ciaB, cj1349, mviN, pldA, tlyA, irgA, hecA, and hecB) was checked in a set of 22 Arcobacter butzleri and 4 Arcobacter cryaerophilus isolates. The pldA and mviN genes were predominant (88.64%). Lower detection rates were observed for tlyA (84.76%), ciaB (84.61%), cadF and cj1349 (76.92%), IrgA and hecA (61.53%), and hecB (57.69%). The findings revealed that a majority of the Campylobacteraceae strains have these putative virulence genes that may lead to pathogenic effects in humans.

Isolation and Identification of Arcobacter Species from Costa Rican Poultry Production and Retail Sources

Arcobacter is a gram-negative rod recognized as a potential food- and waterborne pathogen; nevertheless, little is known about the effects of this pathogen on human and animal health. Although Arcobacter species are commonly found in nature, poultry is suspected to be the main vehicle for the transmission of this pathogen. The aims of this work were to determine the prevalence of Arcobacter spp. in broilers produced in Costa Rica for human consumption and to analyze the pathogenic capacity of the isolates through the detection of virulence genes. One hundred fifty-two samples of cecal content (87 farms), 104 samples of carcass rinse after chiller (six processing plants), and 96 carcass rinses from as many retail stores were analyzed. The suspicious isolates were identified using genus-specific PCR, and species-level identification was achieved with a multiplex PCR. Virulence genes were identified using the protocol described by L. Douidah, L. de Zutter, J. Baré, P. De Vos, P. Vandamme, O. Vandenberg, A.-M. Van den Abeele, and K. Houf (J. Clin. Microbiol. 50:735-741, 2012), which includes nine different virulence genes. The overall isolation frequency of Arcobacter was 6.5% (n = 23). Eight (34.8%) of the isolates came from cecal content, 2 (8.7%) were isolated from samples taken after chiller, and 13 (56.5%) were from retail stores. The species isolated included A. thereius (30.4%), A. butzleri (21.7%), A. skirrowii (4.3%), and A. cibarius (4.3%). The remaining samples were classified as Arcobacter sp. Gene tlyA was the most prevalent virulence gene, present in 9 of 23 samples analyzed; genes hecA and pldA were present in one only strain each. A strain of A. butzleri isolated from a retail store presented the highest number of virulence genes (five), and 11 samples did not present any of the genes analyzed. The results obtained suggest that the presence of virulent Arcobacter isolates in the poultry production chain from Costa Rica could be a risk for individuals who consume the contaminated product.

Occurrence of putative virulence genes on Arcobacter butzleri isolated from three different environmental sites throughout the dairy chain

AIMS

This comparative study investigated the occurrence of cadF, cj1349, ciaB, pldA, tlyA, hecA, hecB, mviN, irgA and IroE genes in 212 Arcobacter butzleri isolated from three different environmental sites linked to the dairy chain (farms, industrial and artisanal dairy plants) located in three Italian regions (Lombardy, Emilia-Romagna and Calabria).

METHODS AND RESULTS

According to the presence of these genes, different pathotypes (P-types) were determined. The main genes detected were ciaB, mviN, tlyA, cj1349, pldA and cadF, while the least common genes were iroE, hecA, hecB and irgA. TlyA, irgA, hecA, hecB and iroE, which were significantly more frequent in isolates recovered in industrial dairy plants. Twelve P-types were detected. The occurrence of the most frequently detected P-types (P-types 1, 2, 3 and 5) differed significantly (P < 0·001) in relation to both the environmental site and geographical area of isolation. The highest diversity in P-types was observed in industrial dairy plants and in the Calabria region.

CONCLUSIONS

The results of this study show a correlation between the occurrence of putative virulence genes and virulence genotype variability depending on the environmental site and geographical origin of the isolates.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present study provides insights into the similar distribution of putative virulence genes in a dairy chain and other sources' isolates and also into a geographical distribution of some P-types. We have shown that industrial dairy plants may represent an environmental site favouring a selection of the isolates with a higher pathogenetic pattern.

Occurrence of emerging food-borne pathogenic Arcobacter spp. isolated from pre-cut (ready-to-eat) vegetables

Given that changes in consumer food behaviours have led to an increase in the demand for pre-cut ready-to-eat (RTE) vegetables, and that few data are currently available on the occurrence of Arcobacter spp. in such foods, the aim of the present study was to assess the occurrence of Arcobacter spp. that carry virulence-associated genes on pre-cut RTE vegetables, using cultural and molecular methods. Arcobacter was detected using biomolecular identification methods in 44/160 (27.5%) of the samples, of which 40/44 (90.9%) isolates corresponded to A. butzleri and 4/44 (9.1%) to A. cryaerophilus. Studying the incidence of 9 virulence-associated genes revealed the widespread distribution of these genes among the Arcobacter isolates tested. The results obtained in our research provided plenty of information on the health risks associated with the direct consumption of raw vegetables, and highlight the need to implement further studies at each level of the production chain, in order to obtain further information to help protect human health.