Identification by 16S ribosomal RNA gene sequencing of Arcobacter butzleri bacteraemia in a patient with acute gangrenous appendicitis

Evidence for high-risk pollutants and emerging microbial contaminants at two major bathing ghats of the river Ganga using high-resolution mass spectrometry and metagenomics

An efficient wastewater treatment plant is imperative to limit the entry of emerging pollutants (EPs) and emerging microbial contaminants (EMCs) in the river ecosystem. The detection of emerging EPs in aquatic environments is challenging due to complex sample preparation methods, and the need for sophisticated accurate analytical tools. In Varanasi (India), the river Ganga holds immense significance as a holy river but is consistently polluted with municipal (MWW) and hospital wastewater (HWW). We developed an efficient method for untargeted detection of EPs in the water samples using High-resolution mass spectrometry (HRMS), and identified 577 and 670 chemicals (or chemical components) in the water samples from two major bathing ghats, Assi Ghat (AG) and Dashashwamedh Ghat (DG), respectively. The presence of EPs of different categories viz chemicals from research labs, diagnostic labs, lifestyle and industrial chemicals, toxins, flavor and food additives indicated the unsafe disposal of MWW and HWW or inefficient wastewater treatment plants (WWTPs). Besides, shotgun metagenomic analysis depicted the presence of bacteria associated with MWW viz Cloacibacterium normanse, Sphaerotilus natans (sewage fungi), E. coli, and Prevotella. Also, the presence of human pathogens Arcobacter, Polynucleobacter, Pseudomonas, Klebsiella, Aeromonas, Acinetobacter, Vibrio, and Campylobacter suggests the discharge of HWW. EPs are linked to the development, and transmission of antimicrobial resistance (AMR). Occurrence of antibiotic resistance genes (ARGs), plasmid-borne β-lactamases, aminoglycoside transferases, and ARGs associated with integrons, transposons and plasmids viz mcr-3 gene that confer resistance to colistin, the last resort of antibiotics confirmed the presence of emerging microbial contaminants. Subsequent genome reconstruction studies showed the presence of uncultivable ARB and transmission of ARGs through horizontal gene transfer. This study can be used to monitor the health of aquatic bodies as well as the efficiency of WWTPs and raise an urgent need for efficient WWTPs to safeguard the river, Ganga.

Prolonged watery diarrhea and malnutrition caused by Aliarcobacter butzleri (formerly Arcobacter butzleri): the first pediatric case in Croatia and a literature review

Aliarcobacter butzleri (formerly Arcobacter butzleri), is a newly recognized Campylobacter-like emerging foodborne pathogen worldwide, usually causing gastrointestinal symptoms in young children. A 4-year-old boy was admitted to the Department of Pediatrics, University Hospital of Split, Croatia, because of malnutrition, lost appetite and prolonged watery diarrhea. A comprehensive diagnostics, including biochemistry, haematology, allergology, microbiology and radiology, were performed. The only positive microbiology result was unexpected isolation of Aliarcobacter butzleri on selective media for Campylobacter, after 48 hours of incubation on 42°C, among microaerophilic atmosphere. Clinical course was favorable and after symptomatic therapy child was discharged in good clinical condition and normal peristalsis to home care, with the recommendation of taking high-protein preparations to improve nutritional status. In addition, we performed a literature review of clinical cases caused by Aliarcobacter butzleri infection. The first report of Aliarcobacter butzleri isolated from stool sample in a 4-year old boy in Croatia, along with other clinical reports in literature, highlights the importance of standardisation and improvement of microbiological analysis, especially implementation of new methods for the identification of emerging pathogens.

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.

Widespread Multidrug Resistance of Arcobacter butzleri Isolated from Clinical and Food Sources in Central Italy

The Arcobacter genus comprises a group of bacteria widely distributed in different habitats that can be spread throughout the food chain. Fluoroquinolones and aminoglycosides represent the most common antimicrobial agents used for the treatment of Arcobacter infections. However, the increasing trend of the antimicrobial resistance of this pathogen leads to treatment failures. Moreover, the test implementation and interpretation are hindered by the lack of reference protocols and standard interpretive criteria. The purpose of our study was to assess the antibiotic resistance pattern of 17 A. butzleri strains isolated in Central Italy from fresh vegetables, sushi, chicken breast, and clinical human samples to provide new and updated information about the antimicrobial resistance epidemiology of this species. Antimicrobial susceptibility testing was carried out by the European Committee on Antimicrobial Susceptibility Testing (EUCAST)'s disc diffusion method. All the strains were multidrug resistant, with 100% resistance to tetracyclines and cefotaxime (third generation cephalosporins). Some differences were noticed among the strains, according to the isolation source (clinical isolates, food of animal origin, or fresh vegetables), with a higher sensitivity to streptomycin detected only in the strains isolated from fresh vegetables. Our data, together with other epidemiological information at the national or European Union (EU) level, may contribute to developing homogeneous breakpoints. However, the high prevalence of resistance to a wide range of antimicrobial classes makes this microorganism a threat to human health and suggests that its monitoring should be considered by authorities designated for food safety.

Comparison of the Diagnostic Accuracy of Three Real-Time PCR Assays for the Detection of Arcobacter butzleri in Human Stool Samples Targeting Different Genes in a Test Comparison without a Reference Standard

Potential etiological relevance for gastroenteric disorders including diarrhea has been assigned to Arcobacter butzleri. However, standard routine diagnostic algorithms for stool samples of patients with diarrhea are rarely adapted to the detection of this pathogen and so, A. butzleri is likely to go undetected unless it is specifically addressed, e.g., by applying pathogen-specific molecular diagnostic approaches. In the study presented here, we compared three real-time PCR assays targeting the genes hsp60, rpoB/C (both hybridization probe assays) and gyrA (fluorescence resonance energy transfer assay) of A. butzleri in a test comparison without a reference standard using a stool sample collection with a high pretest probability from the Ghanaian endemicity setting. Latent class analysis was applied with the PCR results obtained with a collection of 1495 stool samples showing no signs of PCR inhibition to assess the real-time PCR assays' diagnostic accuracy. Calculated sensitivity and specificity were 93.0% and 96.9% for the hsp60-PCR, 100% and 98.2% for the rpoB/C-PCR, as well as 12.7% and 99.8% for the gyrA-PCR, respectively. The calculated A. butzleri prevalence within the assessed Ghanaian population was 14.7%. As indicated by test results obtained with high-titer spiked samples, cross-reactions of the hsp60-assay and rpoB/C-assay with phylogenetically related species such as A. cryaerophilus can occur but are less likely with phylogenetically more distant species like, e.g., A. lanthieri. In conclusion, the rpoB/C-assay showed the most promising performance characteristics as the only assay with sensitivity >95%, albeit associated with a broad 95%-confidence interval. In addition, this assay showed still-acceptable specificity of >98% in spite of the known cross-reactivity with phylogenetically closely related species such as A. cryaerophilus. If higher certainty is desired, the gyrA-assay with specificity close to 100% can be applied for confirmation testing with samples showing positive rpoB/C-PCR results. However, in case of a negative result in the gyrA-assay, this cannot reliably exclude the detection of A. butzleri in the rpoB/C-assay due to the gyrA-assay's very low sensitivity.

Outbreak of Arcobacter butzleri? An emerging enteropathogen

BACKGROUND

Arcobacter butzleri is a gram-negative rod, with microaerobic growth at an optimal temperature of 37°C. It was reported to be the fourth most common Campylobacter-like organism isolated from patients with diarrhoea.

OBJECTIVE

Characterise a potential outbreak of A. butzleri detected in a short period of time in the University Hospital Marqués de Valdecilla.

METHODS

Eight strains of A. butzleri were detected in our hospital in only two months. Isolates were identified by MALDI-TOF MS system and 16S rDNA sequencing. Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) and Pulsed Field Gel Electrophoresis (PFGE) were carried out to assess clonal relationship. Gradient strips (Etest) were used to determine susceptibility by agar diffusion.

RESULTS

ERIC-PCR and PFGE confirmed the lack of clonal relationship between strains. Erythromycin or ciprofloxacin might be appropriate for antibiotic treatment of infections.

CONCLUSIONS

A. butzleri is an emerging pathogen with increasing incidence, and may be underestimated.

Arcobacter Butzleri in an AIDS Patient

Background

Arcobacter butzleri (A. butzleri) is an emerging enteric pathogen increasingly identified in Europe and is likely under-reported in other global regions. We describe to our knowledge the first case report of A. butzleri in an AIDS patient, along with the first documented local (Singapore) case of A. butzleri infection. Case Presentation. A 38-year-old AIDS patient presented with diarrhoea of 2 weeks' duration. Stool cultures yielded A. butzleri. The patient was treated with 3 days of ciprofloxacin with clinical resolution of diarrhoea.

Conclusion

A. butzleri is likely to be present, although under-reported in AIDS patients, and it should be noted as a pathogen of increasing significance.

Microbial community origin and fate through a rural wastewater treatment plant

Conventional wastewater treatment relies on a complex microbiota; however, much of this community is still to be characterised. To better understand the origin, dynamics and fate of bacteria within a wastewater treatment plant: untreated primary wastewater, activated sludge, and post-treatment effluent were characterised. From 3,163 Exact Sequence Variants (ESVs), 860 were annotated to species-level. In primary wastewater, 28% of ESVs were putative bacterial species previously associated with humans, 14% with animals and 5% as common to the environment. Differential abundance analysis revealed significant relative reductions in ESVs from potentially humans-associated species from primary wastewater to activated sludge, and significant increases in ESVs from species associated with nutrient cycling. Between primary wastewater and effluent, 51% of ESVs from human-associated species did not significantly differ, and species such as Bacteroides massiliensis and Bacteroides dorei increased. These findings illustrate that activated sludge increased extracellular protease and urease-producing species, ammonia and nitrite oxidizers, denitrifiers and specific phosphorus accumulators. Although many human-associated species declined, some persisted in effluent, including strains of potential health or environmental concern. Species-level microbial assessment may be useful for understanding variation in wastewater treatment efficiency as well as for monitoring the release of microbes into surface water and the wider ecosystem. This article is protected by copyright. All rights reserved.

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.

Detection of potentially pathogenic Arcobacter spp. in Bangkok canals and the Chao Phraya River

The management of pathogenic bacteria in waterways is a public health issue. Here, we investigated the concentrations of potentially pathogenic bacteria, Arcobacter spp. and Campylobacter spp., and Escherichia coli, by quantifying species-specific genes in surface water samples from canals and the Chao Phraya River from June 2017 to June 2018 in Bangkok, Thailand. We assessed the relationship between the specific bacterial concentrations, water quality, and seasonal changes. Arcobacter spp. were detected at high density in all samples and showed seasonal fluctuations according to analyses based on 16S rDNA and the invasion gene ciaB. High levels of 16S rDNA and dut gene of E. coli were detected in the polluted drainage canals. A high correlation was observed between E. coli and chemical and biochemical oxygen demand (COD and BOD), suggesting that untreated domestic wastewater was the source of the E. coli. In contrast, Arcobacter spp. were detected with high density even in water samples with relatively low COD, suggesting that Arcobacter spp. are more likely than E. coli to survive in the water environment. The analysis of 16S rDNA and ciaB gene sequence analyses indicated that the Arcobacter spp. isolated from the drainage canals were A. butzleri and A. cryaerophilus.

Antimicrobial Resistance and in silico Virulence Profiling of Aliarcobacter butzleri Strains From German Water Poultry

Aliarcobacter butzleri is an emerging foodborne and zoonotic pathogen that is usually transmitted via contaminated food or water. A. butzleri is not only the most prevalent Aliarcobacter species, it is also closely related to thermophilic Campylobacter, which have shown increasing resistance in recent years. Therefore, it is important to assess its resistance and virulence profiles. In this study, 45 Aliarcobacter butzleri strains from water poultry farms in Thuringia, Germany, were subjected to an antimicrobial susceptibility test using the gradient strip diffusion method and whole-genome sequencing. In the phylogenetic analysis, the genomes of the German strains showed high genetic diversity. Thirty-three isolates formed 11 subgroups containing two to six strains. The antimicrobial susceptibility testing showed that 32 strains were resistant to erythromycin, 26 to doxycycline, and 20 to tetracycline, respectively. Only two strains were resistant to ciprofloxacin, while 39 strains were resistant to streptomycin. The in silico prediction of the antimicrobial resistance profiles identified a large repertoire of potential resistance mechanisms. A strong correlation between a gyrA point mutation (Thr-85-Ile) and ciprofloxacin resistance was found in 11 strains. A partial correlation was observed between the presence of the bla3 gene and ampicillin resistance. In silico virulence profiling revealed a broad spectrum of putative virulence factors, including a complete lipid A cluster in all studied genomes.

Aliarcobacter butzleri from Water Poultry: Insights into Antimicrobial Resistance, Virulence and Heavy Metal Resistance

Aliarcobacter butzleri is the most prevalent Aliarcobacter species and has been isolated from a wide variety of sources. This species is an emerging foodborne and zoonotic pathogen because the bacteria can be transmitted by contaminated food or water and can cause acute enteritis in humans. Currently, there is no database to identify antimicrobial/heavy metal resistance and virulence-associated genes specific for A. butzleri. The aim of this study was to investigate the antimicrobial susceptibility and resistance profile of two A. butzleri isolates from Muscovy ducks (Cairina moschata) reared on a water poultry farm in Thuringia, Germany, and to create a database to fill this capability gap. The taxonomic classification revealed that the isolates belong to the Aliarcobacter gen. nov. as A. butzleri comb. nov. The antibiotic susceptibility was determined using the gradient strip method. While one of the isolates was resistant to five antibiotics, the other isolate was resistant to only two antibiotics. The presence of antimicrobial/heavy metal resistance genes and virulence determinants was determined using two custom-made databases. The custom-made databases identified a large repertoire of potential resistance and virulence-associated genes. This study provides the first resistance and virulence determinants database for A. butzleri.

Arcobacter butzleri is an opportunistic pathogen: recurrent bacteraemia in an immunocompromised patient without diarrhoea

Introduction

Arcobacter butzleri is attracting increasing interest due to its possible pathogenic properties. Researchers have described cases in which A. butzleri is isolated in stool samples from patients with gastrointestinal symptoms, mostly diarrhoea. The relevance of adding our case to the literature lies in its description of recurrent A. butzleri bacteraemia in a patient without diarrhoea.

Case presentation

An immunocompromised patient was hospitalized three times within 12 months due to A. butzleri-induced bacteraemia. At no time did the patient experience diarrhoea even though examination of stool samples showed growth of A. butzleri. The isolate was susceptible to gentamicin, colistin and tetracyclines. The patient was successfully treated with doxycycline.

Conclusion

For the first time in the literature we describe recurrent A. butzleri bacteraemia in a patient without diarrhoea. This case supports the classification of A. butzleri as an opportunistic pathogenic species, which clinical microbiology laboratories should be able to identify.

Arcobacter butzleri: Up-to-date taxonomy, ecology, and pathogenicity of an emerging pathogen

Arcobacter butzleri, recently emended to the Aliarcobacter butzleri comb. nov., is an emerging pathogen causing enteritis, severe diarrhea, septicaemia, and bacteraemia in humans and enteritis, stillbirth, and abortion in animals. Since its recognition as emerging pathogen on 2002, advancements have been made in elucidating its pathogenicity and epidemiology, also thanks to advent of genomics, which, moreover, contributed in emending its taxonomy. In this review, we provide an overview of the up-to-date taxonomy, ecology, and pathogenicity of this emerging pathogen. Moreover, the implication of A. butzleri in the safety of foods is pinpointed, and culture-dependent and independent detection, identification, and typing methods as well as strategies to control and prevent the survival and growth of this pathogen are provided.

First Case Report of Human Bacteremia With Malacobacter (Arcobacter) mytili

Arcobacter spp. are commonly associated with shellfish and have been increasingly implicated in human gastrointestinal disease. We report the first case of human bacteremia with Malacobacter (previously Arcobacter) mytili acquired after exposure to Maryland crab. Arcobacter spp. should be considered in febrile illnesses when the history indicates exposure to seafood.

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.

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.

Occurrence of potentially pathogenic arcobacters in shellfish

Considering that several recent cases of human gastroenteritis have been associated with species from the Arcobacter genus, and that few data are currently available about the occurrence of this genus in Italian shellfish, the aim of the present study was to evaluate the occurrence of Arcobacter spp. and the presence of virulence-associated genes. The approach consisted of cultural and biomolecular (multiplex-PCR and 16S-RFLP) methods identifying isolates, followed by PCR assays aimed at the cadF, ciaB, cjl349, irgA, hecA putative virulence genes. Arcobacter spp. was detected in 16/70 (22.8%) shellfish samples. Specifically, Arcobacter spp. was highlighted in 10/42 (23.8%) mussel and in 6/28 (21.4%) clam samples. Subsequently, biomolecular assays revealed Arcobacter butzleri in 12/16 (75%) and Arcobacter cryaerophilus 1B in 4/16 (25%) isolates. PCRs aimed at the five putative virulence genes demonstrated widespread distribution of these genes among Arcobacter isolates and some differences from the results published by other authors. Our research provides more information regarding the health risks associated with the consumption of raw bivalve molluscs and underlines the need to implement an adequate control plan by performing intensive and continuous monitoring in order to guarantee human health.

Prevalence of Arcobacter species among humans, Belgium, 2008-2013

We examined fecal samples from 6,774 patients with enteritis in Belgium, 2008–2013. Members of the genus Arcobacter were the fourth most common pathogen group isolated, and the isolation rate was higher than previously reported. Culturing Arcobacter in a microbiology laboratory is feasible and should thus be tested for in cases of diarrheal disease.

Insights in the pathogenesis and resistance of Arcobacter: A review

Arcobacter genus currently comprises 18 recognized species, among which Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii have been associated with human and animal disease. Although these organisms, with special emphasis A. butzleri, are emerging as clinical pathogens, several aspects of their epidemiology and virulence are only starting to be clarified. In vitro human and animal cell culture assays have been used to show that several Arcobacter species can adhere to and invade eukaryotic cells, induce an immune response and produce toxins that damage host cells. In addition, data from genome sequencing highlighted several potential markers that may be helpful candidates for the study and understanding of these mechanisms; however, more work is necessary to clarify the molecular mechanisms involved in Arcobacter virulence. Arcobacter can be considered a relatively robust organism showing to be able to survive in adverse conditions, as the ones imposed by food processing and storage. Moreover, these bacteria have shown increased antibiotic resistance, along with high multidrug resistance. In this review, we seek to update the state-of-the-art concerning Arcobacter distribution, its interaction with the host, the trends of antibiotic resistance, its ability to survive, and finally the use of natural antimicrobials for control of Arcobacter.

Bacteremia caused by Arcobacter butzleri in an immunocompromised host

Arcobacter butzleri is an emerging pathogen that has been implicated as the causative agent of persistent watery diarrhea. We describe a case involving a patient with chronic lymphocytic leukemia who developed invasive A. butzleri bacteremia. This case illustrates the unique challenges involved in diagnosing infections caused by emerging gastrointestinal pathogens.

Arcobacter butzleri induces a pro-inflammatory response in THP-1 derived macrophages and has limited ability for intracellular survival

Recent case reports have identified Arcobacter (A.) butzleri to be another emerging pathogen of the family Campylobacteraceae causing foodborne diseases. However, little is known about its interaction with the human immune system. As macrophages act as first defense against bacterial infections, we studied for the first time the impact of A. butzleri on human macrophages using THP-1 derived macrophages as an in vitro infection model. Our investigations considered the inflammatory response, intracellular survival and activation of caspases as potential virulence mechanisms employed by A. butzleri. Induction of IL-1α, IL-1ß, IL-6, IL-8, IL-12ß and TNFα demonstrated a pro-inflammatory response of infected macrophages towards A. butzleri. gentamycin protection assays revealed the ability of A. butzleri strains to survive and resist the hostile environment of phagocytic immune cells for up to 22 h. Moreover, initial activation of intitiator- (CASP8) as well as effector caspases (CASP3/7) was observed without the onset of DNA damage, suggesting a potential counter regulation. Intriguingly, we recognized distinct strain specific differences in invasion and survival capabilities. This suggests the existence of isolate dependent phenotype variations and different virulence potentials as known for other intestinal pathogens such as Salmonella enterica ssp.

Culture-independent evaluation of the appendix and rectum microbiomes in children with and without appendicitis

PURPOSE

The function of the appendix is largely unknown, but its microbiota likely contributes to function. Alterations in microbiota may contribute to appendicitis, but conventional culture studies have not yielded conclusive information. We conducted a pilot, culture-independent 16S rRNA-based microbiota study of paired appendix and rectal samples.

METHODS

We collected appendix and rectal swabs from 21 children undergoing appendectomy, six with normal appendices and fifteen with appendicitis (nine perforated). After DNA extraction, we amplified and sequenced 16S rRNA genes and analyzed sequences using CLoVR. We identified organisms differing in relative abundance using ANOVA (p<0.05) by location (appendix vs. rectum), disease (appendicitis vs. normal), and disease severity (perforated vs. non-perforated).

RESULTS

We identified 290 taxa in the study's samples. Three taxa were significantly increased in normal appendices vs. normal rectal samples: Fusibacter (p = 0.009), Selenomonas (p = 0.026), and Peptostreptococcus (p = 0.049). Five taxa were increased in abundance in normal vs. diseased appendices: Paenibacillaceae (p = 0.005), Acidobacteriaceae GP4 (p = 0.019), Pseudonocardinae (p = 0.019), Bergeyella (p = 0.019) and Rhizobium (p = 0.045). Twelve taxa were increased in the appendices of appendicitis patients vs. normal appendix: Peptostreptococcus (p = 0.0003), Bilophila (p = 0.0004), Bulleidia (p = 0.012), Fusobacterium (p = 0.018), Parvimonas (p = 0.003), Mogibacterium (p = 0.012), Aminobacterium (p = 0.019), Proteus (p = 0.028), Actinomycineae (p = 0.028), Anaerovorax (p = 0.041), Anaerofilum (p = 0.045), Porphyromonas (p = 0.010). Five taxa were increased in appendices in patients with perforated vs. nonperforated appendicitis: Bulleidia (p = 0.004), Fusibacter (p = 0.005), Prevotella (p = 0.021), Porphyromonas (p = 0.030), Dialister (p = 0.035). Three taxa were increased in rectum samples of patients with appendicitis compared to the normal patients: Bulleidia (p = 0.034), Dialister (p = 0.003), and Porphyromonas (p = 0.026).

CONCLUSION

Specific taxa are more abundant in normal appendices compared to the rectum, suggesting that a distinctive appendix microbiota exists. Taxa with altered abundance in diseased and severely diseased (perforated) samples may contribute to appendicitis pathogenesis, and may provide microbial signatures in the rectum useful for guiding both treatment and diagnosis of appendicitis.

A severe case of persistent diarrhoea associated with Arcobacter cryaerophilus but attributed to Campylobacter sp. and a review of the clinical incidence of Arcobacter spp

Although rarely, Arcobacter spp. have been associated with diarrhoea and bacteraemia. We report a persistent case in a healthy 26-year-old Spanish male of bloody diarrhoea, which was attributed to Campylobacter but in fact was caused by Arcobacter cryaerophilus, as determined by sequencing of the rpoB gene. The isolate was re-identified by matrix-assisted laser desorption ionization time of flight (MALDI-TOF) and genotyped for five putative virulence genes and for seven genes included in the Arcobacter multilocus sequence typing database. The low score obtained by MALDI-TOF indicates the need to complement the database with more isolates. Only the ciaB gene, which encodes for an invasin, was detected. Despite the isolate belonging to a new sequence type, three of the alleles (glnA, pgm and tkt) had been found previously in isolates from faeces of patients with diarrhoea. This study, together with the reviewed literature, indicates that Arcobacter can produce bacteraemia and that the isolation from patients with diarrhoea range from 0.11% to 1.25%. This study also demonstrates that Arcobacter species are confused with Campylobacter spp., as previously suggested. This is one of the factors that leads to underestimation of their incidence together with the use of inappropriate detection and identification methods.

Presence and analysis of plasmids in human and animal associated arcobacter species

In this study, we report the screening of four Arcobacter species for the presence of small and large plasmids. Plasmids were present in 9.9% of the 273 examined strains. One Arcobacter cryaerophilus and four Arcobacter butzleri plasmids were selected for further sequencing. The size of three small plasmids isolated from A. butzleri and the one from A. cryaerophilus strains ranged between 4.8 and 5.1 kb, and the size of the large plasmid, isolated from A. butzleri, was 27.4 kbp. The G+C content of all plasmids ranged between 25.4% and 26.2%. A total of 95% of the large plasmid sequence represents coding information, which contrasts to the 20 to 30% for the small plasmids. Some of the open reading frames showed a high homology to putative conserved domains found in other related organisms, such as replication, mobilization and genes involved in type IV secretion system. The large plasmid carried 35 coding sequences, including seven genes in a contiguous region of 11.6 kbp that encodes an orthologous type IV secretion system found in the Wolinella succinogenes genome, Helicobacter pylori and Campylobacter jejuni plasmids, which makes this plasmid interesting for further exploration.

Isolation and Phylogenetic Analysis ofArcobacterSpp. in Ground Chicken Meat and Environmental Water in Japan and Thailand

Prevalence of Arcobacter spp. in chicken meat samples and environmental water samples in Japan and Thailand was investigated. Arcobacter was isolated from 48% of chicken meat samples (20/41) and 23% of river water samples (4/17) from Japan, and 100% of chicken meat samples (10/10) and 100% of canal water samples (7/7) from Thailand. A. butzleri was among the species isolated from all positive samples. About 10% genetic diversity was seen in the rpoB-rpoC in Arcobacters, and phylogenetic trees were divided into two clusters. In both countries, the results suggested that chicken and environmental water were highly contaminated with a genetically diverse population of Arcobacter.

Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry for identification of clinically significant bacteria that are difficult to identify in clinical laboratories

AIMS

Although the revolutionary matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) has been evaluated for identification of various groups of bacteria, its application in bacteria that are 'difficult-to-identify' by phenotypic tests has been less well studied. We aim to evaluate the usefulness of MALDI-TOF MS for identification of 'difficult-to-identify' bacterial isolates.

METHODS

We evaluated the performance of the Bruker MALDI-TOF MS system for a collection of 67 diverse clinically important bacterial isolates that were less commonly encountered, possessed ambiguous biochemical profiles or belonged to newly discovered species. The results were compared with 16S rRNA gene sequencing as a reference method for species identification.

RESULTS

Using 16S rRNA gene sequencing as the reference method, 30 (45%) isolates were identified correctly to species level (score ≥2.0), 20 (30%) were only identified to genus level (score ≥1.7), four (6%) were misidentified (incorrect species with score ≥2.0 or incorrect genus with score ≥1.7) and 13 (19%) showed 'no identification' (score <1.7). Aerobic Gram-positive bacteria showed the highest percentage of correct species identification, followed by aerobic Gram-negative, anaerobic Gram-positive and anaerobic Gram-negative bacteria. Sixteen isolates identified to genus level actually showed the correct species but with scores below the threshold for species identification. Most isolates which showed 'no identification' were due to the absence of the corresponding species in the Bruker database.

CONCLUSIONS

Expansion of commercial databases to include reference spectra of less commonly encountered and newly discovered species and to increase available spectra for each species is required to improve the accuracy of MALDI-TOF MS for identifying 'difficult-to-identify' bacteria.

Emerging pathogen Arcobacter spp. in acute gastroenteritis: molecular identification, antibiotic susceptibilities and genotyping of the isolated arcobacters

The aims of this study were as follows: (i) to isolate Arcobacter spp. from the stool samples of patients with gastroenteritis; (ii) to identify them with molecular methods; (iii) to genotype them using enterobacterial repetitive intergenic consensus (ERIC)-PCR; and (iv) to determine their antibiotic susceptibilities. For the study, a total of 3287 diarrhoeal stool samples submitted to the Microbiology Laboratory of the Kayseri Training and Research Hospital, Kayseri, Turkey, between 2010 and 2011 were analysed. Campylobacter blood-free selective medium supplemented with cefoperazone, amphotericin B and teicoplanin was used for isolation. Medium inoculated with stool samples was incubated microaerobically at 37 °C for 72-96 h. Phenotypic tests, a genus-specific PCR and a multiplex PCR were used to identify the arcobacters, whilst ERIC-PCR was used for genotyping and the antibiotic susceptibilities of the isolates were detected by E-test. Arcobacter spp. were isolated from nine of the 3287 samples. These nine isolates were identified as Arcobacter butzleri and all showed different ERIC-PCR profiles. All nine isolates were resistant to ampicillin and susceptible to gentamicin, tetracycline, erythromycin and ciprofloxacin. As far as is known, this is the first study in which A. butzleri has been isolated from human acute gastrointestinal infections in Turkey. According to these results, it is recommended that, when investigating the aetiology of infections of the digestive system in humans, Arcobacter spp. be considered for inclusion. The results of this study should contribute to our knowledge related to A. butzleri infections in humans.

Occurrence of putative virulence genes in arcobacter species isolated from humans and animals

Interest in arcobacters in veterinary and human public health has increased since the first report of the isolation of arcobacters from food of animal origin. Since then, studies worldwide have reported the occurrence of arcobacters on food and in food production animals and have highlighted possible transmission, especially of Arcobacter butzleri, to the human population. In humans, arcobacters are associated with enteritis and septicemia. To assess their clinical relevance for humans and animals, evaluation of potential virulence factors is required. However, up to now, little has been known about the mechanisms of pathogenicity. Because of their close phylogenetic affiliation to the food-borne pathogen Campylobacter and their similar clinical manifestations, the presence of nine putative Campylobacter virulence genes (cadF, ciaB, cj1349, hecA, hecB, irgA, mviN, pldA, and tlyA) previously identified in the recent Arcobacter butzleri ATCC 49616 genome sequence was determined in a large set of human and animal Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii strains after the development of rapid and accurate PCR assays and confirmed by sequencing and dot blot hybridization.

In silico analysis of 16S rRNA gene sequencing based methods for identification of medically important aerobic Gram-negative bacteria

This study provides guidelines on the usefulness of full and 527 bp 16S rRNA gene sequencing and Microseq databases for identifying medically important aerobic Gram-negative bacteria. Overall, full and 527 bp 16S rRNA gene sequencing can identify 26.1 % and 32.6 %, respectively, of medically important aerobic Gram-negative bacteria confidently to the species level, whereas the full-MicroSeq and 500-MicroSeq databases can identify 15.2 % and 26.1 %, respectively, of medically important aerobic Gram-negative bacteria confidently to the species level. Among the major groups of aerobic Gram-negative bacteria, the methods and databases are least useful for identification of Aeromonas, Bordetella and Bartonella species. None of the Aeromonas species can be confidently or doubtfully identified, whereas only 0 % and 0-33.3 % of Bordetella species and 0-10 % and 0-10 % of Bartonella species can be confidently and doubtfully identified, respectively. On the other hand, these methods and databases are most useful for identification of members of the families Pasteurellaceae and Legionellaceae and Campylobacter species: 29.6-59.3 % and 7.4-18.5 % of members of Pasteurellaceae, 36-52 % and 12-24 % of members of Legionellaceae, and 26.7-60 % and 0-13.3 % of Campylobacter species can be confidently and doubtfully identified, respectively. Thirty-nine medically important aerobic Gram-negative bacteria that should be confidently identified by full 16S rRNA gene sequencing are not included in the full-MicroSeq database. Twenty-three medically important aerobic Gram-negative bacteria that should be confidently identified by 527 bp 16S rRNA gene sequencing are not included in the 500-MicroSeq database. Compared with results of our previous studies on anaerobic and Gram-positive bacteria, full and 527 bp 16S rRNA gene sequencing are able to confidently identify significantly more anaerobic Gram-positive and Gram-negative bacteria than aerobic Gram-positive and Gram-negative bacteria.

Taxonomy, epidemiology, and clinical relevance of the genus Arcobacter

The genus Arcobacter, defined almost 20 years ago from members of the genus Campylobacter, has become increasingly important because its members are being considered emergent enteropathogens and/or potential zoonotic agents. Over recent years information that is relevant for microbiologists, especially those working in the medical and veterinary fields and in the food safety sector, has accumulated. Recently, the genus has been enlarged with several new species. The complete genomes of Arcobacter butzleri and Arcobacter nitrofigilis are available, with the former revealing diverse pathways characteristic of free-living microbes and virulence genes homologous to those of Campylobacter. The first multilocus sequence typing analysis showed a great diversity of sequence types, with no association with specific hosts or geographical regions. Advances in detection and identification techniques, mostly based on molecular methods, have been made. These microbes have been associated with water outbreaks and with indicators of fecal pollution, with food products and water as the suspected routes of transmission. This review updates this knowledge and provides the most recent data on the taxonomy, species diversity, methods of detection, and identification of these microbes as well as on their virulence potential and implication in human and animal diseases.

High prevalence of arcobacter carriage in older subjects with type 2 diabetes

Arcobacters are potential pathogens related to diarrheic infections and, rarely, septicaemia. This study evaluated the prevalence of arcobacters in stool samples of subjects with (n = 38) and without (n = 61) type 2 diabetes by using cultural and molecular techniques. Three Arcobacter positive cultures were found, all among diabetic subjects, whereas molecular analysis showed a carriage rate of 79% and 26.2% in subjects with and without type 2 diabetes (P < .001), respectively. The multivariate analysis showed that type 2 diabetes (beta = 1.913; 95%CI: 2.378-19.285; P < .0001) and age (beta = 1.744; 95%CI: 2.077-15.766; P = .001) were the only factors independently associated with arcobacters colonization in this population. Our study demonstrated a high prevalence of arcobacters colonization in type 2 diabetic and older subjects. The clinical significance and the potential health risk associated with these emerging species remain to be determined.

Association analysis of the general environmental conditions and prokaryotes' gene distributions in various functional groups

The activities of prokaryotes are pivotal in shaping the environment, and at the same time are greatly influenced by the environment. By using the genomic data and environmental descriptions of the complete prokaryotic genomes in NCBI's Microbial Genome Project Database and applying statistical methods, we have identified in a systematic manner those gene groups whose presence/frequency patterns are different for organisms of different environmental conditions. Here environmental conditions are characterized in four dimensions--salinity, oxygen requirement, habitat and temperature, and are based on the controlled vocabularies that NCBI's Microbial Genome Project database uses to specify the organism information; and, gene groups are determined as Clusters of Orthologous Groups (COG) and KEGG Orthology (KO) groups. These identified COG and KO groups are considered as potentially correlated with certain environmental conditions, and are then mapped to the COG general categories and KEGG pathways to determine which part of the functional machinery of prokaryotic cells are correlated with the environments. The observations derived from the analysis of the COG and KO groups that are potentially correlated with the oxygen requirement and habitat conditions are in general consistent with existing studies on properties of organisms living in different conditions of these two environmental factors. To further assess the identified correlation relationships, we have also examined whether the environmental conditions are predictable based on the gene distributions in the selected COG and KO groups. The misclassification rates of the prediction experiments are much smaller than that rendered by random guessing, indicating the existence of the correlation relationships between organisms' environmental conditions and gene distributions in certain functional groups. However, the rather moderate misclassification rates (the 25- and 75-percentiles of the misclassification rates of all prediction experiments are 16.79% and 24.06%, respectively) also indicate that the correlation relationships between environmental conditions and gene distributions in certain functional groups are not strong enough for one to decisively define the other.

Enteric pathogen sampling of tourist restaurants in Bangkok, Thailand

BACKGROUND

Travelers' diarrhea (TD) is the most prevalent disorder affecting travelers to developing countries. Thailand is considered "moderately risky" for TD acquisition, but the risk by city visited or behavior of the visitor has yet to be definitely defined. Restaurant eating is consistently associated with the acquisition of diarrhea while traveling, and pathogen-free meals serve as a marker of public health success. This study seeks to ascertain a traveler's risk of exposure to certain bacterial gastric pathogens while eating at Bangkok restaurants recommended in popular tourist guide books.

METHODS

A cross-sectional tourist restaurant survey was conducted. Thirty-five restaurants recommended in the two top selling Bangkok guidebooks on Amazon.com were sampled for bacterial pathogens known to cause diarrhea in Thailand, namely Salmonella, Campylobacter, and Arcobacter (a Campylobacter-like organism). A total of 70 samples from two meals at each restaurant were obtained. Suspected bacterial pathogens were isolated by differential culture and tested for antibiotic resistance.

RESULTS

Salmonella group E was isolated from one meal (2%), and Arcobacter butzleri from nine meals (13%). Campylobacter spp. were not found. The large majority of A butzleri isolates were resistant to azithromycin but susceptible to ciprofloxacin and an aminoglycoside.

CONCLUSIONS

A traveler's risk of exposure to established bacterial pathogens, Salmonella and Campylobacter, by eating in recommended restaurants is small. Arcobacter butzleri exposure risk is 13% per meal eaten, and rises to 75% when 10 meals are eaten. All restaurants, regardless of price, appear to be equally "risky." Current evidence points to Arcobacter being pathogenic in humans; however, further research is needed to conclusively define pathogenicity. Routine prophylaxis for diarrhea is not recommended; however, travelers should be aware of the risk and come prepared with adequate and appropriate self-treatment medications.

Identification of five human and mammal associated Arcobacter species by a novel multiplex-PCR assay

A multiplex-PCR assay with seven primers was developed for the identification of the five human and mammal related species of the emerging foodborne pathogen Arcobacter. The assay was validated using 58 reference and 358 collection strains isolated from humans and mammals. The selected primers on the 23 S RNA gene amplify a 2061 bp fragment from A. butzleri, a 1590 bp fragment from A. thereuis, a 1125 bp fragment from A. cibarius and an A. skirrowii specific fragment of 198 bp. For A. cryaerophilus, a primer set on the gyrA gene amplified a specific fragment of 395 bp. No PCR product was generated for closely related bacteria including Campylobacter and Helicobacter species. Furthermore, examination of the 23 S RNA gene of A. cryaerophilus revealed, besides large heterogeneity, the presence of intervening sequences ranging from 87 to 196 bp.

The presence of Arcobacter species in breeding hens and eggs from these hens

The presence of Arcobacter spp. in 2 breeding hen flocks was determined by examination of the intestinal tract, oviduct magnum mucosa, and ovarian follicles of slaughtered chicken. The bacteria were detected by PCR and cultural isolation in 34 out of 40 intestinal tracts from one flock (A) and 6 out of 30 from the other (B). The strains were Arcobacter butzleri, Arcobacter cryaerophilus, and Arcobacter skirrowii. From flock A, arcobacters were recovered from 6 out of 40 oviduct magnum mucosa samples. The majority of isolated strains were A. butzleri. Arcobacter spp. could not be detected, by either PCR or isolation, from 20 eggs collected on the farm of flock A and from 20 eggs still remaining in the vagina of hens in flock B. Furthermore, none of the ovarian follicles from each flock were positive. The results indicate that breeding hens can be infected with Arcobacter spp. in the intestinal tract and oviduct. No evidence was obtained for transmission of Arcobacter spp. from hens to eggs.

The complete genome sequence and analysis of the epsilonproteobacterium Arcobacter butzleri

BACKGROUND

Arcobacter butzleri is a member of the epsilon subdivision of the Proteobacteria and a close taxonomic relative of established pathogens, such as Campylobacter jejuni and Helicobacter pylori. Here we present the complete genome sequence of the human clinical isolate, A. butzleri strain RM4018.

METHODOLOGY/PRINCIPAL FINDINGS

Arcobacter butzleri is a member of the Campylobacteraceae, but the majority of its proteome is most similar to those of Sulfuromonas denitrificans and Wolinella succinogenes, both members of the Helicobacteraceae, and those of the deep-sea vent Epsilonproteobacteria Sulfurovum and Nitratiruptor. In addition, many of the genes and pathways described here, e.g. those involved in signal transduction and sulfur metabolism, have been identified previously within the epsilon subdivision only in S. denitrificans, W. succinogenes, Sulfurovum, and/or Nitratiruptor, or are unique to the subdivision. In addition, the analyses indicated also that a substantial proportion of the A. butzleri genome is devoted to growth and survival under diverse environmental conditions, with a large number of respiration-associated proteins, signal transduction and chemotaxis proteins and proteins involved in DNA repair and adaptation. To investigate the genomic diversity of A. butzleri strains, we constructed an A. butzleri DNA microarray comprising 2238 genes from strain RM4018. Comparative genomic indexing analysis of 12 additional A. butzleri strains identified both the core genes of A. butzleri and intraspecies hypervariable regions, where <70% of the genes were present in at least two strains.

CONCLUSION/SIGNIFICANCE

The presence of pathways and loci associated often with non-host-associated organisms, as well as genes associated with virulence, suggests that A. butzleri is a free-living, water-borne organism that might be classified rightfully as an emerging pathogen. The genome sequence and analyses presented in this study are an important first step in understanding the physiology and genetics of this organism, which constitutes a bridge between the environment and mammalian hosts.