Detection of Arcobacter species in gastric samples from swine

Gastric ulcers in finishing pigs: the evaluation of selected non-dietary risk factors and impact on production performance

BACKGROUND

The complex aetiology of gastric lesions in pigs remains largely unknown and effective preventive measures and pharmaceutical treatment of the disease have not been developed yet. Regardless of the fact that the overwhelming majority of previous research works dealing with gastric ulceration in pigs focused on the role of the nutritional determinants, including chemical composition of feeds, cereal type, finely ground pelleted diets, and feed additives, conclusions presented therein remain highly ambiguous. Thus, the purpose of this study was to evaluate the impact of the disease on production performance, and investigate the influence of selected non-dietary risk factors on the prevalence of gastric alterations in finishing pigs reared under conditions of 11 modern farms located in Poland.

RESULTS

A total number of 26,043 finishing pigs was examined. 15,228 (58.47%) had gastric ulcers. Intact stomachs were detected in 6176 animals (23.71%). Parakeratosis and erosion were observed in 2551 (9.80%) and 2088 (8.02%), respectively. Among eight continuous variables two were found to be significantly associated with prevalence of the gastric ulcer: the growing number of animals in the herd, which was negatively correlated (P = 0.002; ρ = -0.37), and the growing average entry weight of animals transported to the finisher farm (P = 0.047; ρ = 0.24), which increased the risk of gastric ulcers prevalence. Among 12 nominal variables, problems with the quality of farm management (P = 0.041), and usage of straw as a bedding material (P = 0.002) were identified as determinants significantly associated with occurrence of the analysed health problem.

CONCLUSIONS

Among 20 non-nutritional variables analysed in our study only few factors were found to be associated with the prevalence of the disease. The impact of broadly understood management issues on gastric health in finishing pigs deserves further research.

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 and characteristics of fastidious Campylobacteraceae species in porcine samples

This study investigated the prevalence and characteristics of Campylobacteraceae including a range of fastidious species in porcine samples. Over a thirteen month period caecal contents (n=402) and pork carcass swabs (n=401) were collected from three pork abattoirs and pork products (n=399) were purchased at point of sale in the Republic of Ireland. Campylobacteraceae isolates were recovered by enrichment, membrane filtration and incubation in antibiotic free media under a modified atmosphere (3% O2, 5% H2, 10% CO2 and 82% N2). Campylobacteraceae isolates were identified as either genus Campylobacter or Arcobacter and then selected species were identified by Polymerase Chain Reaction (PCR). Campylobacteraceae were isolated from 103 (26%) caecal samples, 42 (10%) carcass swabs, and 59 (15%) pork products. Campylobacter coli was the most commonly isolated species found in (37%) all sample types but many fastidious species were also isolated including Campylobacter concisus (10%), Arcobacter butzleri (8%), Campylobacter helveticus (8%), Campylobacter mucosalis (6%), Arcobacter cryaerophilus (3%), Campylobacter fetus subsp. fetus (1%), Campylobacter jejuni subsp. jejuni (1%), Campylobacter lari (0.5%), Campylobacter curvus (0.5%) and Arcobacter skirrowii (0.5%). Among all isolates, 83% contained cadF and 98% flaA. In this study 35% of porcine C. coli were resistant to ciprofloxacin but none of the fastidious species demonstrated any resistance to this drug. The level of resistance to erythromycin was very high (up to 100%) in C. concisus and C. helveticus and this is a real concern as this is the current empiric drug of choice for treatment of severe gastroenteritic Campylobacter infections. The study shows that there is a much wider range of fastidious Campylobacteraceae present in porcine samples than previously assumed with C. concisus the second most common species isolated. The majority of fastidious Campylobacteraceae isolates obtained contained virulence genes and antibiotic resistance indicating potential public health significance.

Rapid and accurate detection of Arcobacter contamination in commercial chicken products and wastewater samples by real-time polymerase chain reaction

An SYBR Green real-time polymerase chain reaction (PCR) assay was developed for Arcobacter detection in food and wastewater samples. The assay was applied to 36 chicken and 33 wastewater samples, and the results were compared with those obtained for conventional PCR, multiplex PCR, and culture isolation. Isolates were identified by multiplex PCR and restriction fragment length polymorphism analysis of PCR-amplified DNA fragment, and typed by randomly amplified polymorphic DNA. Arcobacter sp. was detected in 25 of the 26 chicken carcasses (96%) and in 4 of the 10 liver samples (40%) by real-time PCR. Twenty-five chicken samples were positive also by conventional PCR, but in most of them the detection was only possible after 48-h enrichment. Arcobacter butzleri was the most frequently detected species. Twenty-four Arcobacter isolates were obtained from chicken samples, where A. butzleri is the only identified species. All the wastewater samples (100%) were positive for Arcobacter sp. by real-time PCR without enrichment. A. butzleri and Arcobacter cryaerophilus were detected by multiplex PCR. Fifteen samples were found to be positive by culture. Thirty-six isolates were obtained; all of them were identified as A. butzleri by multiplex PCR. However, by PCR-restriction fragment length polymorphism, 34 were identified as A. butzleri, 1 as A. cryaerophilus, and another 1 as Arcobacter skirrowii. A great genetic heterogeneity was observed by randomly amplified polymorphic DNA-PCR profiling. The real-time PCR assay developed in this work showed better detection levels than conventional PCR, together with shorter times of testing samples. Therefore, it could be used as a rapid and accurate instrument for monitoring Arcobacter contamination levels in food and water samples.

Bacterial diversity in Fez tanneries and Morocco's Binlamdoune River, using 16S RNA gene based fingerprinting

Tannery wastewater causes serious ecological and sanitary damage. Chemical analysis of water from Binlamdoune River of the medina of Fez was conducted and the results revealed the presence of toxic elements from tanneries and other industrial activities, which strongly affected water quality. To determine the effectiveness of bioremediation for depollution, we studied the abundance and diversity of bacteria residing in these polluted environments. Conducting denaturing gradient gel electrophoresis (PCR-DGGE) of the 16S rDNA area using primers related to bacteria showed a bacterial community belonging to eubacterial groups, that is, Epsilonproteobacteria, Clostridia, Lactobacillales, Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria. In addition, cloning displayed the presence of clones belonging to the Firmicutes group. Moreover, scanning electron microscopy revealed a significant heterogeneity of microorganism forms and structures. These endogenous microbes could have a significant role in the purification of Binlamdoune River and Fez tannery wastewater.

Bacterial diversity and White Plague Disease-associated community changes in the Caribbean coral Montastraea faveolata

Increasing evidence confirms the crucial role bacteria and archaea play within the coral holobiont, that is, the coral host and its associated microbial community. The bacterial component constitutes a community of high diversity, which appears to change in structure in response to disease events. In this study, we highlight the limitation of 16S rRNA gene (16S rDNA) clone library sequencing as the sole method to comprehensively describe coral-associated communities. This limitation was addressed by combining a high-density 16S rRNA gene microarray with, clone library sequencing as a novel approach to study bacterial communities in healthy versus diseased corals. We determined an increase in diversity as well as a significant shift in community structure in Montastraea faveolata colonies displaying phenotypic signs of White Plague Disease type II (WPD-II). An accumulation of species that belong to families that include known coral pathogens (Alteromonadaceae, Vibrionaceae), bacteria previously isolated from diseased, stressed or injured marine invertebrates (for example, Rhodobacteraceae), and other species (for example, Campylobacteraceae) was observed. Some of these species were also present in healthy tissue samples, but the putative primary pathogen, Aurantimonas corallicida, was not detected in any sample by either method. Although an ecological succession of bacteria during disease progression after causation by a primary agent represents a possible explanation for our observations, we also discuss the possibility that a disease of yet to be determined etiology may have affected M. faveolata colonies and resulted in (or be a result of) an increase in opportunistic pathogens.

Prevalence and diversity of Arcobacter spp. in the Czech Republic

The aim of this study was to examine 634 samples of chicken, lamb, pork, beef, fish, samples from the intensive animal industry and from poultry for slaughter, as well as from the domestic breeding of poultry, horses, pigs, and lambs, from surface water, and from clinical samples for the presence of Arcobacter. All the samples were examined with a cultivation method, followed by confirmation by multiplex PCR. The method of multiplex PCR applied directly to a liquid medium after enrichment was applied only to the samples with the highest probability of the presence of arcobacters. Arcobacter spp. were detected in 11.8% of the samples, of which A. butzleri, A. cryaerophilus, and A. skirrowii were found in 6.6, 5.1, and 0.2% of the samples, respectively. The sources of the arcobacters were chicken meat from the retail market, intensive animal production facilities, domestic chicken breeding facilities, lamb raising environments, surface water and wastewater, and beef swabs taken in a meat processing factory. No occurrence of arcobacters was identified in the swabs from slaughter turkeys, ducks, and wild poultry. No arcobacters were found in horse and pig breeding environments, on pork, or on the swabs of fish. Forty-two rectal swabs taken from humans were also free of Arcobacter. Seventeen isolates of Arcobacter were further identified by sequencing the 16S rRNA gene. Varied genotypes were observed among A. butzleri from chicken meat and chicken breeds, and A. cryaerophilus from wastewater and chicken breeds. They were similar to the genotypes present in wastewater, porcine feces, human stool, and human blood obtained from databases. Our results revealed that the chicken meat from the retail market is an important source of arcobacters. Cross-contamination during handling of chicken carcass practices could play a key role in the spread of Arcobacter.

Isolation of various Arcobacter species from domestic geese (Anser anser)

In this study, the prevalence and distribution of various Arcobacter spp. were investigated in samples taken from the cloacae of healthy domestic geese raised in Turkey. A membrane filtration technique with a non-selective blood agar was employed after enrichment in Arcobacter enrichment broth (AEB) to isolate a wide range of Arcobacter spp. In addition, the isolates were characterized phenotypically and identified at species level using a multiplex-PCR assay. A total of 90 cloacal swab samples taken from geese, collected on three farms (18, 25, 47 samples, respectively), were examined. Of the samples examined, 16 (18%) were found positive for Arcobacter. One Arcobacter species was isolated from each bird. Of the 16 Arcobacter isolates, 7 (44%), 7 (44%) and 2 (12.5%) were identified by m-PCR as A. cryaerophilus, A. skirrowii and A. butzleri, respectively. The present study indicates that domestic geese can harbour a variety of Arcobacter spp. in their cloacae. The presence of Arcobacter in geese may be of significance as reservoirs in their dissemination. Detailed research is needed for better understanding of the epidemiology and zoonotic potential of this emerging pathogen.

Characterization of the Arcobacter contamination on Belgian pork carcasses and raw retail pork

In the present study, the occurrence of Arcobacter was assessed at four sites on 169 porcine carcasses (foreleg, chest, pelvis and ham) at different stages of slaughter and 47 pork products at retail. Carcass swab samples were enriched in Arcobacter broth containing 5-fluorouracil, amphotericine B, cefoperazone, novobiocine and trimethoprim as selective supplement. After microaerobic incubation, arcobacters were isolated using Arcobacter selective agar plates, containing the selective supplement described above. Some carcass samples and all pork samples were also examined quantitatively. All 862 isolates were identified by a species-specific m-PCR-assay and 182 isolates were further characterized by ERIC-PCR. Arcobacters were isolated from one or more sampling places on 96.4% of the carcasses, with the foreleg and the chest area as the two most contaminated sites. Furthermore, A. cryaerophilus was the most common species. Chilling decreased the number of positive carcasses, but did not eliminate all arcobacters. Direct isolation revealed that only a few carcasses were contaminated with arcobacters on foreleg and/or chest at levels higher than 10(2 )cfu/100 cm(2). Characterization demonstrated a large heterogeneity among the isolates, with ten genotypes present on more then one site per carcass. Fourteen genotypes were simultaneously present on carcasses from different herds slaughtered on the same day, which may indicate cross-contamination. Arcobacters were present in 21% of the pork samples taken at retail, but contamination levels did not exceed 100 cfu per gram. Characterization of the A. butzleri and A. cryaerophilus isolates indicated an additional contamination during processing at retail.

Cell proliferation in pathogenesis of esophagogastric lesions in pigs

Esophagogastric ulcer is an independent disease in swine that is characterized by ulcerous autodigestion of the cutaneous mucosa, which does not exhibit a tendency to recover, but, on the contrary, a tendency toward severe hemorrhaging, with a predominantly lethal outcome. Since it develops in the part of the stomach that is morphologically and functionally different from other glandular mucosa, it was questioned earlier whether it could be a peptic ulcer based on its nature. Spontaneous ulcers, usually of the stomach, commonly occur in many domestic animals. Some of these lesions are chronic and they may occur in either the glandular or squamous-lined regions of the stomach. As with the human disease, the pathogenesis in domestic animals is multifactorial, poorly understood, and variable between and within species. Environmental stress and dietary factors are very important in the ulcer disease in swine. It has been shown that the Helicobacter spp. is strongly associated with naturally occurring ulcer and preulcer lesions of the pars esophagea in swine, which raises the possibility that Helicobacter spp. is an important factor in the pathogenesis of these lesions. The dynamics of the development of esophagogastric ulcers imply hyperplastic lesions (parakeratosis and hyperkeratosis), keratolysis, erosions, peptic necrosis, and the development of ulcers with all the characteristics of peptic ulcerations in other localities. In addition, K6 is expressed in association with the mucosal changes. The pattern of the intermediate filaments of keratin suggests that epithelial proliferation, which leads to visible hyperkeratosis, constitutes the essence of gastric ulcers in swine.

Isolation and characterization of the emerging foodborn pathogen Arcobacter from human stool

At present, isolation of arcobacters from human specimens is performed by slightly of not modified Campylobacter, Yersinia or Leptospira isolation techniques, and knowledge if arcobacters are part of the human commensal flora is lacking. Therefore, an Arcobacter selective isolation procedure was validated for the examination of human fecal specimens, and the presence and characteristics of Arcobacter in feces of asymptomatic humans was examined in order to assess the clinical relevance of arcobacters in diarrheal stool. With this method, Arcobacter was isolated from seven of 500 (1.4%) stool samples of healthy people with Arcobacter cryaerophilus as the only species present. Seven A. cryaerophilus genotypes were detected and only one genotype was found per person. Neither A. butzleri nor A. skirrowii were isolated, therefore the presence of those latter species in clinical samples requires further attention. Though the pathogenic role and potential virulence factors of arcobacters have to be further examined, the current status of arcobacters as emerging pathogens remains justified.

Development of a multiplex and real time PCR assay for the specific detection of Arcobacter butzleri and Arcobacter cryaerophilus

A new multiplex PCR and two specific TaqMan assays were developed to target the emerging pathogens A. butzleri and A. cryaerophilus. The assays also included an internal control to verify the presence of bacterial target DNA and amplification integrity. The multiplex assay used a published primer set (CRY1 and CRY2) for detecting A. cryaerophilus DNA (Houf, K., Tutenel, A., De Zutter, L., Van Hoof, J. and Vandamme, P., 2000. Development of a multiplex PCR assay for the simultaneous detection and identification of Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii. FEMS microbiology letters, 193 (1): 89-94.) and a novel A. butzleri primer set designed to target the rpoB/C gene sequences. To improve sample throughput and assay sensitivity a TaqMan assay for each Arcobacter spp. was developed which again utilised the heterogeneity contained in the rpoB/C and 23s rRNA gene sequences. The two TaqMan assays provided >2 log improvement in detection sensitivity for both Arcobacter spp. compared with the multiplex PCR assay and were able to detect <10 CFU per PCR reaction. To evaluate the effectiveness of the Arcobacter TaqMan assays with field isolates the assays were used to screen DNA samples prepared from faecal, hide and environmental samples obtained from two meat processing plants. In these studies, the TaqMan assays revealed that 2/150 (1.3%) samples were A. butzleri-positive, 11/150 (7.3%) were A. cryaerophilus-positive and the identity of generated amplicons was confirmed by DNA sequencing. Our results show that these TaqMan assays provide improvements in sensitivity and species-representation over other published Arcobacter PCR assays and they are compatible with detecting Arcobacters in sub-optimal matrices.

Arcobacter cibarius sp. nov., isolated from broiler carcasses

Twenty Gram-negative, rod-shaped, slightly curved, non-spore-forming bacteria that gave a negative result in Arcobacter species-specific PCR tests but that yielded an amplicon in an Arcobacter genus-specific PCR test were isolated from 13 unrelated broiler carcasses. Numerical analysis of the profiles obtained by SDS-PAGE of whole-cell proteins clustered all isolates in a single group distinct from the other Arcobacter species. DNA-DNA hybridization among four representative strains exhibited DNA binding values above 91 %. DNA-DNA hybridization with reference strains of the current four Arcobacter species revealed binding levels below 47 %. The G+C contents ranged between 26.8 and 27.3 mol%. Pairwise comparison of 16S rRNA gene sequences revealed the mean values for similarity to the type strain of Arcobacter cryaerophilus (97.5 %), Arcobacter butzleri (96.5 %), Arcobacter skirrowii (96.0 %) and Arcobacter nitrofigilis (95.0 %). The levels of similarity to Campylobacter and Helicobacter species were below 88 and 87 %, respectively. The isolates could be distinguished from other Arcobacter species by the following biochemical tests: catalase, oxidase and urease activities; reduction of nitrate; growth at 25 and 37 degrees C under aerobic conditions; growth on 2-4 % (w/v) NaCl media; and susceptibility to cephalothin. These data demonstrate that the 20 isolates represent a single novel Arcobacter species, for which the name Arcobacter cibarius sp. nov. is proposed, with LMG 21996(T) (=CCUG 48482(T)) as the type strain.

Occurrence and strain diversity of Arcobacter species isolated from healthy Belgian pigs

In this study, Arcobacter species were isolated from clinically healthy porkers and sows on four unrelated pig farms, using a quantitative isolation protocol. Isolates were identified by m-PCR, and fingerprints were distinguished by modified ERIC-PCR. The prevalence of Arcobacter in pigs ranged from 16 to 85%. Arcobacter excretion ranged from 0 to 10(4) CFUg(-1) feces. Arcobacter butzleri was the most frequently occurring species, but simultaneous shedding of two or three species occurred. Large heterogeneity among the Arcobacter species was detected in pigs and on the farms.

Isolation of Arcobacter species from animal feces

A previously developed Arcobacter isolation protocol for poultry skin and meat was validated for the isolation of Arcobacter from feces of livestock animals. Good repeatability, in-lab reproducibility and sensitivity were achieved and the specificity was improved by additional incorporation of cycloheximide and increase of the novobiocin concentration in the selective supplement. The limit of detection of quantitative and qualitative analysis was 10(2) and 10(0) cfu g(-1) feces, respectively. From fecal samples collected at slaughterhouse, Arcobacter was isolated from 43.9% of porcine, 39.2% of bovine, 16.1% of ovine and 15.4% of equine samples. All three animal-associated Arcobacter species were isolated and levels up to 10(3) cfu g(-1) feces were determined.

Isolation and characterisation of Arcobacter butzleri from meat

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

The prevalence of Arcobacter spp. on chicken carcasses sold in retail markets in Turkey, and identification of the isolates using SDS-PAGE

In this study, the prevalence of Arcobacter spp. on chicken carcasses sold in various retail markets in Turkey was investigated. The isolates were characterized and identified using various phenotypic and molecular tests. The membrane filtration technique employing 0.45-microm pore size membrane filters laid onto a nonselective blood agar was used after enrichment in Oxoid Arcobacter Enrichment Broth (AEB) to examine a total of 75 chicken carcasses (44 fresh and 31 frozen). Species level identification was performed using SDS-PAGE of whole-cell proteins and a recently developed multiplex-PCR assay. All isolates were identified as Arcobacter butzleri. Of the 44 fresh chicken carcasses examined, 42 (95%) were positive for A. butzleri. A. butzleri was also recovered from seven (23%) of the 31 frozen carcasses examined.

Determination of the occurrence of Arcobacter butzleri in beef and dairy cattle from Texas by various isolation methods

Arcobacter butzleri is a pathogenic bacterium that has been found in dairy cattle, pigs, poultry, and humans. As of this writing, there are no data on the incidence of A. butzleri in beef cattle. Given the differences in rearing practices used for feedlot cattle and those used for dairy cattle, differences in the incidences of this organism in various types of cattle may also exist. Numerous culture methods have been used to isolate A. butzleri, but there are few data on the comparative efficacies of these methods. The objectives of this study were to determine the incidence of A. butzleri in cattle from Texas and to compare the effectiveness levels of the Johnson-Murano (JM) method (consisting of enrichment in JM broth followed by plating on JM agar) and the Collins method (consisting of enrichment in EMJH-P80 broth followed by plating on Cephalothin, Vancomycin, and Amphotericin B [CVA] agar) in the isolation of this organism. Fifty cattle each from two feedlots, a dairy, and a stocker yard were sampled. Fecal swabs were obtained from cattle, and each sample was cultured by the JM method, the Collins method, and combinations of the two methods with the broth of one method being used with the agar of the other. Polymerase chain reaction was used to identify the isolates for confirmation of A. butzleri. Samples from 18 of 200 cattle tested positive for A. butzleri. This organism was detected by the JM method in 4.5% of the samples and by the Collins method in 2.5% of the samples. An incidence of 4.0% was found when JM broth was used with CVA agar, while no samples tested positive for A. butzleri when EMJH-P80 broth was used with JM agar.

Risk factors for gastric ulcers in Australian pigs at slaughter

The stomachs of pigs (n=15,741) originating from 136 herds from the Australian states of Queensland, Western Australia, Victoria and New South Wales were examined at slaughter for the presence of oesophago-gastric ulcers (OGUs). Stomachs were categorised as being normal, hyperkeratotic, eroded, ulcerated, or having strictures. A questionnaire was distributed to piggery owners to identify factors associated with an above-average herd prevalence of OGU. Thirty percent of all pigs examined had OGU (median within-herd prevalence of 17%). The median within-herd prevalence in Victoria (53%) was significantly higher than in Western Australia (30%) or Queensland (7%). The prevalence of OGU in culled breeding animals was significantly higher than in porkers or baconers from the same herds. There was no difference between the prevalence of OGU in male and female pigs sampled from the same Western Australian herds. The relationship between OGU and herd and pig risk factors was assessed by random effects logistic-regression analysis. Herds with a high prevalence of OGU were more likely to feed ad libitum (OR=13.7), use automated feeding systems (OR=7.8), feed a pelleted ration (OR=384) and get water from a dam rather than from a bore or river (OR=3.8). Furthermore, for every change in the ration formulation for finisher pigs, the risk of OGU increased 1.5 times.

Identification of Arcobacter cryaerophilus isolated from a traffic accident victim with bacteremia by 16S ribosomal RNA gene sequencing

Traditional ways of identifying slow growing bacteria is slow and often difficult. In this study, a small, Gram-negative, facultative anaerobic, slow growing bacillus was isolated from the blood culture of a 7-year old traffic accident victim. The bacterium was non-hemolytic, catalase and oxidase positive. An attempt to use the Vitek system (GNI+) and the API system (20NE) to identify the strain was unsuccessful as the growth controls showed negative results. 16S ribosomal RNA gene sequencing showed that there was 1 base difference between the isolate and Arcobacter cryaerophilus (GenBank Accession no. U25805), 1 base difference between the isolate and A. cryaerophilus (GenBank Accession no. U34387), 10 base differences between the isolate and A. cryaerophilus (GenBank Accession no. L14624), 34 base differences between the isolate and A. butzleri (GenBank Accession no. U34386), 34 base differences between the isolate and A. butzleri (GenBank Accession no. U34387), and 38 base differences between the isolate and A. butzleri (GenBank Accession no. L14626), indicating that the isolate most closely resembled a strain of A. cryaerophilus. Identification of the isolate in our case by conventional methods was difficult, as the absence of a curved morphology has made it confused with other Gram-negative non-fermentative bacteria, and the slow growth rate has made it unidentifiable by both the Vitek and API systems. Although the exact source of infection and route of transmission in our case remains elusive, we speculate that the bacteria were transmitted through the respiratory tract while the boy was suffocated in the mud. The present report represents an example of showing the usefulness of 16S rRNA gene sequencing for identification of slow growing bacteria.

Genotypic variation among arcobacter isolates from a farrow-to-finish swine facility

Arcobacter spp. were isolated from nursing sows and developing pigs on three farms of a farrow-to-finish swine operation and market-age pigs at slaughter. Isolates were identified by polymerase chain reaction and genotypic fragment patterns were examined by pulsed-field gel electrophoresis (PFGE). Incidences of Arcobacter-positive samples increased progressively as the pigs aged, resulting in all of the pens at the end of the growth cycle in the finishing barn containing Arcobacter-positive feces. However, only 10 of 350 cecal samples from slaughtered pigs were positive. There was little similarity between genotypic patterns for Arcobacter collected from the three farms. The level of genotypic variation revealed by PFGE suggested that pigs in this farrow-to-finish operation were colonized by multiple Arcobacter parent genotypes that may have undergone genomic rearrangement, common to members of Campylobacteraceae, during successive passages through the animals. Additionally, the level of genotypic diversity seen among Arcobacter isolates from farms of a single farrow-to-finish swine operation suggests an important role for genotypic phenotyping as a source identification and monitoring tool during outbreaks.

Development of a multiplex PCR assay for the simultaneous detection and identification of Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii

A multiplex PCR assay with five primers targeting the 16S and 23S rRNA genes was developed for the simultaneous detection and identification of Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii. The selected primers amplify a 257-bp fragment from A. cryaerophilus, a 401-bp fragment from A. butzleri and a 641-bp fragment from A. skirrowii. No PCR product was generated for closely related bacteria including Campylobacter and Helicobacter species. The assay was useful to identify cultures after in vitro cultivation and to detect and identify A. butlzeri and A. cryaerophilus from poultry samples present in 24-h old enrichment in Arcobacter broth with cefoperazone, amphotericin and teicoplanin (CAT)-supplement.

Helicobacter species colonizing pig stomach: molecular characterization and determination of prevalence

The infection rate of 60 pigs (10 pigs from each of six farms) by Helicobacter species was studied by two techniques. Histological examination of the cardiac area of the stomach yielded a 58% positive result versus an 80% positive result by PCR with genus-specific primers. Eighty percent of the 16S rRNA gene was amplified, classified in four groups by PCR-restriction fragment length polymorphism, and sequenced. Isolates from all farms except one (farm C) were identified as Helicobacter heilmannii type 1, while those from farm C were identified as H. heilmannii type 2. Attempts to culture this organism in vitro failed. Helicobacter pylori was not found in these animals.

The largest subunits of RNA polymerase from gastric helicobacters are tethered

The rpoB and rpoC genes of eubacteria and archaea, coding respectively for the beta- and beta'-like subunits of DNA-dependent RNA polymerase, are organized in an operon with rpoB always preceding rpoC. The genome sequence of the gastric pathogen Helicobacter pylori (strain 26695) revealed homologs of two genes in one continuous open reading frame that potentially could encode one 2890-amino acid-long beta-beta' fusion protein. Here, we show that this open reading frame does in fact encode a fused beta-beta' polypeptide. In addition, we establish by DNA sequencing that rpoB and rpoC are also fused in each of four other unrelated strains of H. pylori, as well as in Helicobacter felis, another member of the same genus. In contrast, the rpoB and rpoC genes are separate in two members of the related genus Campylobacter (Campylobacter jejuni and Campylobacter fetus) and encode separate RNA polymerase subunits. The Campylobacter genes are also unusual in overlapping one another rather than being separated by a spacer as in other Gram-negative bacteria. We propose that the unique organization of rpoB and rpoC in H. pylori may contribute to its ability to colonize the human gastric mucosa.