Contribution of mono- and co-culture of Pseudomonas paralactis, Acinetobacter MN21 and Stenotrophomonas maltophilia to the spoilage of chill-stored lamb

Exploring the contribution of common microorganisms to spoilage is of great significance in inhibiting spoilage in lamb. This work investigated the extent of protein degradation and profile changes of free amino acids (FAAs), free fatty acids (FFAs) and volatile organic compounds (VOCs) in lamb caused by single- and co-culture of the common aerobic spoilage bacteria, P. paralactis, Ac. MN21 and S. maltophilia. Meanwhile, some key VOCs produced by the three bacteria during lamb spoilage were also screened by orthogonal partial least square discriminant analysis and difference value in VOCs content between inoculated groups and sterile group. Lamb inoculated with P. paralactis had the higher total viable counts, pH, total volatile base nitrogen and TCA-soluble peptides than those with the other two bacteria. Some FAAs and FFAs could be uniquely degraded by P. paralactis but not Ac. MN21 and S. maltophilia, such as Arg, Glu, C15:0, C18:0 and C18:1n9t. Co-culture of the three bacteria significantly promoted the overall spoilage, including bacterial growth, proteolysis and lipolysis. Key VOCs produced by P. paralactis were 2, 3-octanedione, those by Ac. MN21 were 1-octanol, octanal, hexanoic acid, 1-pentanol and hexanoic acid methyl ester, and that by S. maltophilia were hexanoic acid. The production of extensive key-VOCs was significantly and negatively correlated with C20:0, C23:0 and C18:ln9t degradation. This study can provide a basis for inhibiting common spoilage bacteria and promoting high-quality processing of fresh lamb.

Pharmacokinetics of tulathromycin in pregnant ewes (Ovis aries) challenged with Campylobacter jejuni

The purpose of this study was to evaluate the pharmacokinetics of tulathromycin in the plasma and maternal and fetal tissues of pregnant ewes when administered within 24 hours of a single, IV Campylobacter jejuni (C. jejuni) challenge. Twelve, pregnant ewes between 72-92 days of gestation were challenged IV with C. jejuni IA3902 and then treated with 1.1 ml/45.36 kg of tulathromycin subcutaneously 18 hours post-challenge. Ewes were bled at predetermined time points and euthanized either at a predetermined time point or following the observation of vaginal bleeding or abortion. Following euthanasia, tissues were collected for bacterial culture, pharmacokinetics and histologic examination. The maximum (geometric) mean tulathromycin plasma concentration was estimated at 0.302 μg/mL, with a peak level observed at around 1.2 hours. The apparent systemic clearance of tulathromycin was estimated at 16.6 L/h (or 0.28 L/kg/h) with an elimination half-life estimated at approximately 22 hours. The mean tissue concentrations were highest in the uterus (2.464 μg/g) and placentome (0.484 μg/g), and were lowest in fetal liver (0.11 μg/g) and fetal lung (0.03 μg/g). Compared to previous reports, results of this study demonstrate that prior IV administration of C. jejuni appeared to substantially alter the pharmacokinetics of tulathromycin, reducing both the peak plasma concentrations and elimination half-life. However, additional controlled trials are required to confirm those observations.

Prevalence, Genotypic and Phenotypic Characterization and Antibiotic Resistance Profile of Clostridium perfringens Type A and D Isolated from Feces of Sheep (Ovis aries) and Goats (Capra hircus) in Punjab, Pakistan

Clostridium perfringens poses a serious threat to small ruminants by causing moderate to severe enterotoxaemia. Due to its ability to produce a wide arsenal of toxins, it is ranked among the most prevalent and important pathogens in livestock. This study focused on the molecular characterization of different Clostridium perfringens types along with their antimicrobial resistance profile. An overall higher prevalence of C. perfringens (46.1%) was detected based on mPCR among sheep and goats (healthy and diseased) in the Punjab province, Pakistan. The majority of the isolates were characterized as type A (82%), followed by type D (18%). Among the isolates from diseased sheep and goats, 27% were positive for cpa, 49% for cpa and cpb2, 9% for cpa and etx, 15% for cpa, cpb2 and etx. In the case of isolates from healthy sheep and goats, 59% were positive for cpa, 34% for cpb2 and cpa, 4% for cpa and etx, and 3% for cpa, cpb2 and etx. The prevalence of the beta2 toxin gene in the diseased sheep and goat population was 64% as compared to 37% in healthy animals. All 184 isolates (100%) were sensitive to rifampin and ceftiofur; the majority (57%) was sensitive to teicoplanin, chloramphenicol, amoxicillin, linezolid and enrofloxacin. A lower proportion of isolates (43%) were sensitive to ciprofloxacin and only 14% were susceptible to erythromycin. The findings of this study highlight the higher prevalence of C. perfringens in small ruminants and indicate that detailed pathogenesis studies are necessary to understand the explicit role of various toxins in causing enteric infections in sheep and goats including how they might be exploited to develop vaccines against these diseases.

Investigation of chronic infection by Leptospira spp. in asymptomatic sheep slaughtered in slaughterhouse

The study aimed to evaluate the histopathological characteristics of renal lesions in chronically infected sheep and with low titers of anti-Leptospira antibodies from a slaughterhouse. In the serological analysis, 24.74% (48/194) presented seroreactivity with a titer equal to or greater than 100. Among these seroreactive sheep, titers of 100 were predominant (58.33%, 28/48), with the highest titer being 1,600 (2.08%, 1/48). Serogroup Sejroe (sv. Hardjo) was the most frequent at 35.42% (17/48). Leptospiral DNA was verified in 4.12% (8/194) of the kidney samples tested, and no urine sample was positive. All the samples corresponded to the pathogenic species L. interrogans. The eight amplicons with 202-nucleotides were identical with two mismatches (presented 100% of identity) using the PCR targeting to secY gene. Histological sections of PCR-positive kidneys were submitted to direct detection by the anti-LipL32 immunohistochemistry (IHC) technique. The Leptospira spp. antigen was evident in 62.5% (5/8) of the kidneys. Positive staining was observed in the cytoplasm of tubular cells and in the form of brownish aggregates that adhered to tubular epithelial cells and projected into the lumen. Inflammatory lymphoplasmacytic infiltrate, ranging from mild to moderate, with multifocal distribution, was the predominant finding in seroreactive animals (33.33%, 16/48). The demonstration of the leptospiral antigen lining the renal tubules through IHC of naturally infected sheep confirmed by PCR characterizes renal colonization in a species with the presence of histological changes compatible with leptospirosis.

A pilot study of the effects of Mycoplasma ovipneumoniae exposure on domestic lamb growth and performance

Mycoplasma ovipneumoniae is a globally distributed pathogen that has been associated with pneumonia in both domestic and wild Caprinae. It is closely related to M. hyopneumoniae, a respiratory pathogen of swine that is associated with decreased growth rates of pigs as well as clinical respiratory disease. In order to assess the effects of M. ovipneumoniae on lamb performance, we generated a cohort of lambs free of M. ovipneumoniae by segregation of test negative ewes after lambing, then compared the growth and carcass quality traits of M. ovipneumoniae-free and -colonized lambs from weaning to harvest. Some signs of respiratory disease were observed during the feeding trial in both lamb groups, but the M. ovipneumoniae-exposed group included more affected lambs and higher average disease scores. At harvest, lungs of lambs in both groups showed few grossly visible lesions, although the M. ovipneumoniae-exposed group did exhibit increased microscopic lung lesions (P<0.05). In addition, M. ovipneumoniae exposed lambs produced lower average daily gains (P<0.05), and lower yield grade carcasses (P<0.05) compared to those of non-exposed lambs. The results demonstrated the feasibility of test and segregation for elimination of M. ovipneumoniae from groups of sheep and suggested that this pathogen may impair lamb growth and productivity even in the absence of overt respiratory disease.

Antibiotic Susceptibility and Virulence Factors in Escherichia coli from Sympatric Wildlife of the Apuan Alps Regional Park (Tuscany, Italy)

Today a growing number of studies are focusing on antibiotic resistance in wildlife. This is due to the potential role of wild animals as reservoirs and spreaders of pathogenic and resistant bacteria. This study focused on isolating and identifying Escherichia coli from the feces of wild animals living in the Apuan Alps Regional Park (Tuscany, Italy) and evaluating some of their antibiotic resistance and pathogenicity traits. Eighty-five fecal samples from different species were studied. Seventy-one E. coli were identified by matrix assisted laser desorption ionization-time of flight mass spectrometry analysis, subjected to antibiograms and polymerase chain reaction for the detection of antibiotic resistance genes and pathogenicity factors. The highest resistance rates were found against cephalothin (39.4%) and ampicillin (33.8%), followed by amoxicillin/clavulanic acid (15.5%), streptomycin (12.7%), and tetracycline (5.6%). Regarding resistance genes, 39.4% of the isolates were negative for all tested genes. The remaining isolates were positive for bla_CMY-2, sul2, strA-strB and aadA1, tet(B), and tet(A), encoding resistance to beta-lactams, trimethoprim/sulfamethoxazole, streptomycin, and tetracycline, respectively. With regard to virulence factors, 63.4% of the isolates were negative for all genes; 21.1% carried astA alone, which is associated with different pathotypes, 9.9% carried both escV and eaeA (aEPEC); single isolates (1.4%) harbored escV (aEPEC), escV associated with astA and eaeA (aEPEC), astA with stx2 and hlyA (EHEC) or astA and stx1, stx2, and hlyA (EHEC). These results show that wildlife from nonanthropized environments can be a reservoir for antibiotic-resistant microorganisms and suggest the need for a deeper knowledge on their origin and diffusion mechanisms through different ecological niches.

Vaginal biota number is smaller in tailed than docked hair ewes (Ovis aries), but is not affected by copulation

A greater accumulation of feces could facilitate the entrance of bacteria or inert particles into the vagina, particularly while mating tailed ewes. Two experiments were performed to determine if the tail has an active role in the growth of bacterial flora and the entrance of inert material in the vagina after mating, during induced or natural estrus. Twenty ewes were used, 10 tailed and 10 docked. All ewes displayed estrus after CIDR treatment, and half of them; 5 tailed and 5 docked were exposed to rams during the first experiment. For the second experiment, the rest of the animals were mated 15-17 d later at spontaneous estrus. In the induced estrus, no differences in the number of CFU/mL in docked or tailed ewes were observed before mating, but after mating, CFU values tended to be greater in docked than tailed ewes, and the number of inert particles was greater in docked than tailed ewes (5.8 ± 1.3 vs 1.6 ± 0.6, P = 0.024). During natural estrus, docked ewes had less CFU/mL than tailed ewes (19.6 × 10³ ± 0.4 vs 80.0 × 10³ ± 0.0, P = 0.006) before mating, and a similar tendency was maintained after mating, when the number of inert particles was similar in docked and tailed ewes. Staphylococcus and Escherichia were observed in the induced estrus, while in the natural estrus, even though these were the more frequent, five other genera of bacteria were observed. It was concluded that the presence of the tail protects the vaginal environment against increases of the biota load.

A comparison of nonlinear mixed models and response to selection of tick-infestation on lambs

Tick-borne fever (TBF) is stated as one of the main disease challenges in Norwegian sheep farming during the grazing season. TBF is caused by the bacterium Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus. A sustainable strategy to control tick-infestation is to breed for genetically robust animals. In order to use selection to genetically improve traits we need reliable estimates of genetic parameters. The standard procedures for estimating variance components assume a Gaussian distribution of the data. However, tick-count data is a discrete variable and, thus, standard procedures using linear models may not be appropriate. Thus, the objectives of this study were twofold: 1) to compare four alternative non-linear models: Poisson, negative binomial, zero-inflated Poisson and zero-inflated negative binomial based on their goodness of fit for quantifying genetic variation, as well as heritability for tick-count and 2) to investigate potential response to selection against tick-count based on truncation selection given the estimated genetic parameters from the best fit model. Our results showed that zero-inflated Poisson was the most parsimonious model for the analysis of tick count data. The resulting estimates of variance components and high heritability (0.32) led us to conclude that genetic determinism is relevant on tick count. A reduction of the breeding values for tick-count by one sire-dam genetic standard deviation on the liability scale will reduce the number of tick counts below an average of 1. An appropriate breeding scheme could control tick-count and, as a consequence, probably reduce TBF in sheep.

Microbial Detoxification of Deoxynivalenol (DON), Assessed via a Lemna minor L. Bioassay, through Biotransformation to 3-epi-DON and 3-epi-DOM-1

Mycotoxins are toxic metabolites produced by fungi. To mitigate mycotoxins in food or feed, biotransformation is an emerging technology in which microorganisms degrade toxins into non-toxic metabolites. To monitor deoxynivalenol (DON) biotransformation, analytical tools such as ELISA and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) are typically used. However, these techniques do not give a decisive answer about the remaining toxicity of possible biotransformation products. Hence, a bioassay using Lemna minor L. was developed. A dose-response analysis revealed significant inhibition in the growth of L. minor exposed to DON concentrations of 0.25 mg/L and higher. Concentrations above 1 mg/L were lethal for the plant. This bioassay is far more sensitive than previously described systems. The bioassay was implemented to screen microbial enrichment cultures, originating from rumen fluid, soil, digestate and activated sludge, on their biotransformation and detoxification capability of DON. The enrichment cultures originating from soil and activated sludge were capable of detoxifying and degrading 5 and 50 mg/L DON. In addition, the metabolites 3-epi-DON and the epimer of de-epoxy-DON (3-epi-DOM-1) were found as biotransformation products of both consortia. Our work provides a new valuable tool to screen microbial cultures for their detoxification capacity.

Detection of Rickettsia hoogstraalii, Rickettsia helvetica, Rickettsia massiliae, Rickettsia slovaca and Rickettsia aeschlimannii in ticks from Sardinia, Italy

Tick-borne diseases represent a large proportion of infectious diseases that have become a world health concern. The presence of Rickettsia spp. was evaluated by standard PCR and sequencing in 123 ticks collected from several mammals and vegetation in Sardinia, Italy. This study provides the first evidence of the presence of Rickettsia hoogstralii in Haemaphysalis punctata and Haemaphysalis sulcata ticks from mouflon and Rickettsia helvetica in Ixodes festai ticks from hedgehog. In addition, Rickettsia massiliae, Rickettsia slovaca and Rickettsia aeschlimannii were detected in Rhipicephalus sanguineus, Dermacentor marginatus and Hyalomma marginatum marginatum ticks from foxes, swine, wild boars, and mouflon. The data presented here increase our knowledge of tick-borne diseases in Sardinia and provide a useful contribution toward understanding their epidemiology.

Comparison of Serological Tests Based on Outer Membrane or Internal Antigens for Detecting Antibodies to Brucella Ovis in Infected Flocks

The aim of this work was to compare the performance of 6 serological tests using outer or internal antigens from Brucella for the diagnosis of Brucella ovis infection in sheep in an endemic area. Outer membrane antigens included a hot saline extract (HS) and the rough lipopolysaccharide (R-LPS) from B. ovis. Internal antigens were LPS-free total cytosolic proteins (CP) and an 18-kDa cytosolic protein (p18) from Brucella spp. Sera from 200 sheep from naturally infected flocks were assayed by agar gel immunodiffusion test (AGID) and by complement fixation test (CFT), both using HS, and by 4 ELISA using HS, R-LPS, CP, and p18, respectively. The percentage of positive results was 45.5% for ELISA with HS, 42.0% for ELISA with p18, 39.5% for CFT, 33.5% for ELISA with R-LPS, 29.0% for ELISA with CP, and 18.0% for AGID. Taking CFT as the reference test for calculating relative test parameters, the ELISA with HS had the best sensitivity (96.2%), while AGID and the ELISA with R-LPS had the best specificity (96.6%). The ELISA with CP was not more sensitive than the ELISA with p18 (67.1% vs. 79.7%) in spite of the higher number of antigens in CP. The lower relative sensitivity of tests using internal antigens might reflect a lack of antibodies to cytosolic proteins in some infected animals or a shorter persistence of these antibodies relative to antibodies to outer membrane components after recovery from infection.

Occurrence and antimicrobial resistance of emergent Arcobacter spp. isolated from cattle and sheep in Iran

This study is conducted to determine the occurrence and antimicrobial resistance of Arcobacter spp. isolated from clinically healthy food animals. A total of 308 samples from cattle (200) and sheep (108) were collected from Shiraz slaughterhouse, southern Iran to investigate the presence of the important Arcobacter spp. using cultivation and Polymerase Chain Reaction (PCR) methods. Antimicrobial susceptibility of Arcobacter isolates was determined for 18 antibiotics using disk diffusion method. Among 308 samples, 27 (8.7%) and 44 (14.28%) were positive for the presence of Arcobacter species with cultivation and PCR procedures, respectively. The predominant species was A. butzleri in both cattle (58.33%) and sheep (55%). In addition, concurrent incidence of the species was observed in 25% of the positive samples. All Arcobacter isolates were resistant to rifampicin, vancomycin, ceftriaxone, trimethoprim and cephalothin. The isolates showed high susceptibility to tetracycline, oxytetracycline, erythromycin, ciprofloxacin, kanamycin, amikacin, gentamicin and enrofloxacin. No significant difference among cattle and sheep isolates in resistance pattern was observed. The results indicate that cattle and sheep are significant intestinal carriers for Arcobacter spp. Moreover, tetracycline and aminoglycosides showed great effects on Arcobacter species in antibiogram test and can be used for treatment of human Arcobacter infections.

Detection of mycobacterium avium subsp. paratuberculosis in cheeses from small ruminants in Tuscany

Paratuberculosis is an infectious disease which affects mainly domestic and wild ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map). Map has been associated with human diseases like Crohn disease, type-1 diabetes, sarcoidosis, multiple sclerosis and Hashimoto's thyroiditis. The aim of this study was to determine the level of Map positivity of cheeses produced in Tuscany (Italy) as an indication of human exposure to the specific pathogen. Sampling was focused on artisanal cheeses produced without commercial starter culture from raw sheep or goat milk, on small-scale farms. Samples were tested by quantitative PCR (qPCR) and culture. Map DNA was detected in 4/7 (57.14%) goat, and in 14/25 (56%) sheep cheeses by qPCR, whereas cultivation produced a positive result in only one case. This corresponded to a goat cheese that had also reacted positively by qPCR and yielded a viable Type S (sheep) strain of Map. The Map load of the tested samples based on qPCR ranged from 6×10 to 1.8×10(4)Map cells/g of cheese. The results indicate on average 56.57% and 66.6% positivity of cheese samples and farms, respectively. Hence, the type of cheeses that were analyzed within the context of this study seem to constitute a considerable source of human exposure to Map; although the question remains of whether the Map cells were present in a viable form, since positive results were almost exclusively recorded by qPCR.

Continuous, low-dose oral exposure to sodium chlorate reduces fecal generic Escherichia coli in sheep feces without inducing clinical chlorate toxicosis

Our objectives were to determine an effective, yet safe, daily dose of sodium chlorate for reducing fecal shedding of generic Escherichia coli in mature ewes. In a completely randomized experimental design, 25 Targhee ewes (age ∼ 18 mo; BW = 62.5 ± 7.3 kg, mean ± SD) were assigned randomly to 1 of 5 sodium chlorate treatments, which were administered in the drinking water for 5 consecutive days. Treatments were control group (no sodium chlorate) and 4 targeted levels of daily sodium chlorate intake: 30, 60, 90, and 120 mg · kg(-1) BW · d(-1) for 5 d. Individual ewe ad libitum intake of water (with treatments) was measured daily, and BW was measured at the beginning of and 15 and 51 d after the 5-d treatment period. Serum chlorate, whole blood methemoglobin and packed-cell volume (PCV), and fecal generic E. coli and general Enterobacteriaceae coliforms were measured from corresponding samples collected at the end of the 5-d treatment period. Average daily intakes of sodium chlorate from drinking water treatments were 95%, 91%, 90%, and 83% of the target treatment intakes of 30, 60, 90, and 120 mg · kg(-1) BW · d(-1), respectively. Daily sodium chlorate intake remained constant for all treatment groups except for ewes offered 120 mg NaClO3 · kg(-1) BW · d(-1), which decreased (quadratic; P = 0.04) over the course of the 5-d treatment period. This decrease in sodium chlorate intake indicated that the 120-mg NaClO3 level may have induced either toxicity and/or an aversion to the drinking water treatment. Serum chlorate concentrations increased (quadratic; P < 0.001) with increasing sodium chlorate intake. At the end of the 5-d treatment period, mean (least squares ± SEM) serum chlorate concentrations for ewes offered 30, 60, 90, and 120 mg NaClO3 · kg(-1) BW · d(-1) were 15.6 ± 14.1, 32.8 ± 15.8, 52.9 ± 14.1, and 90.3 ± 14.1 μg/mL, respectively. Whole blood methemoglobin and PCV were similar (P = 0.31 to 0.81) among the control group and ewes offered sodium chlorate. Likewise, BW was not affected by sodium chlorate (P > 0.27). Ewes consuming approximately 55 mg NaClO3 · kg(-1) BW · d(-1) or more (i.e., ewes offered 60, 90, and 120 mg) had a >1.4 log unit reduction in fecal E. coli and Enterobacteriaceae coliforms compared with control ewes. We suggest that for a short-term, 5-d dosing strategy, 55 to 81 mg NaClO3 · kg(-1) BW · d(-1) is an effective, yet safe, daily oral dose range for mature ewes to achieve a 97% to 99% reduction in fecal shedding of generic E. coli.

Pros and cons of ion-torrent next generation sequencing versus terminal restriction fragment length polymorphism T-RFLP for studying the rumen bacterial community

The development of next generation sequencing has challenged the use of other molecular fingerprinting methods used to study microbial diversity. We analysed the bacterial diversity in the rumen of defaunated sheep following the introduction of different protozoal populations, using both next generation sequencing (NGS: Ion Torrent PGM) and terminal restriction fragment length polymorphism (T-RFLP). Although absolute number differed, there was a high correlation between NGS and T-RFLP in terms of richness and diversity with R values of 0.836 and 0.781 for richness and Shannon-Wiener index, respectively. Dendrograms for both datasets were also highly correlated (Mantel test = 0.742). Eighteen OTUs and ten genera were significantly impacted by the addition of rumen protozoa, with an increase in the relative abundance of Prevotella, Bacteroides and Ruminobacter, related to an increase in free ammonia levels in the rumen. Our findings suggest that classic fingerprinting methods are still valuable tools to study microbial diversity and structure in complex environments but that NGS techniques now provide cost effect alternatives that provide a far greater level of information on the individual members of the microbial population.

Waddlia chondrophila infects and multiplies in ovine trophoblast cells stimulating an inflammatory immune response

Background

Waddlia chondrophila (W. chondrophila) is an emerging abortifacient organism which has been identified in the placentae of humans and cattle. The organism is a member of the order Chlamydiales, and shares many similarities at the genome level and in growth studies with other well-characterised zoonotic chlamydial abortifacients, such as Chlamydia abortus (C. abortus). This study investigates the growth of the organism and its effects upon pro-inflammatory cytokine expression in a ruminant placental cell line which we have previously utilised in a model of C. abortus pathogenicity.

Methodology/Principal Findings

Using qPCR, fluorescent immunocytochemistry and electron microscopy, we characterised the infection and growth of W. chondrophila within the ovine trophoblast AH-1 cell line. Inclusions were visible from 6 h post-infection (p.i.) and exponential growth of the organism could be observed over a 60 h time-course, with significant levels of host cell lysis being observed only after 36 h p.i. Expression of CXCL8, TNF-α, IL-1α and IL-1β were determined 24 h p.i. A statistically significant response in the expression of CXCL8, TNF-α and IL-1β could be observed following active infection with W. chondrophila. However a significant increase in IL-1β expression was also observed following the exposure of cells to UV-killed organisms, indicating the stimulation of multiple innate recognition pathways.

Conclusions/Significance

W. chondrophila infects and grows in the ruminant trophoblast AH-1 cell line exhibiting a complete chlamydial replicative cycle. Infection of the trophoblasts resulted in the expression of pro-inflammatory cytokines in a dose-dependent manner similar to that observed with C. abortus in previous studies, suggesting similarities in the pathogenesis of infection between the two organisms.

Prevalence of O157:H7 and non-O157 E. coli in Iranian domestic sheep

The aim of the present study was the isolation of both E. coli O157 and non-O157 in sheep. Verotoxins (VT) 1, 2 and eae genes were tested for this propose. Sheep faces are an important source of Shiga toxin-producing Escherichia coli (STEC). Escherichia coli O157:H7 is a highly virulent food-borne pathogen and threat to public health. Rectal swab samples from sheep were collected during 2009-2010. Conventional plating and Polymerase Chain Reaction (PCR) were carried out according to virulence factors (Stx1, Stx2 and eaeA).There significant differences between prevalence of STEC and session were observed. It was at highest in spring and late summer. Six (3.92%) sheep carcasses were contaminated by E. coli O157:H7.Only six samples were positive by PCR specific for the VT2 gene and produced verocytotoxin VT2, whereas all isolates were negative for the presence of VT1 and eae virulence genes considered. Geographical variations and season may be influenced in the prevalence rate. The composition of the gastrointestinal flora may be changed by different diet and, therefore O157 STEC rate in sheep and lamb was different. Iranian sheep indicated as a natural host of E. coli O157 strains therefore, may be potentially pathogenic for humans. This is the first report of E. coli O157 detection from sheep in Iran.

Effects of the comminution rate and microbial contamination of particles in the rumen on in situ estimates of protein and amino acid digestion of expeller palm kernel and rapeseed meal

BACKGROUND

Microbial corrected effective in situ estimates of ruminal undegraded fraction (RU) and intestinal effective digestibility (IED) of dry matter (DM), crude protein (CP) and amino acids (AA) of expeller palm kernel (EPK) and rapeseed meal (RSM) were measured on three rumen- and duodenum-cannulated wethers using ¹⁵N labelling techniques and considering ruminal rates of comminution (k(c)) and outflow (k(p)) of particles.

RESULTS

The lack of k(c) and microbial correction overestimated the RU of DM by 4.91% (EPK) and 9.88% (RSM). The lack of this correction also overestimated in both feeds the RU of CP, individual and total (TAA) AA as well as the IED of DM, CP, TAA and most AA. RU estimates were higher for CP than for TAA, but the opposite was observed for IED. The intestinal digested fraction was higher for CP than for TAA: 17.4% (EPK) and 13.8% (RSM). Digestion led to large changes in the essential AA profile in both feeds.

CONCLUSION

The lack of k(c) and microbial correction as well as CP-based results leads to considerable overestimations in the protein use of both feeds. Digestion aggravates the lysine deficiency of EPK but has global positive effects in the absorbed profile of RSM.

Falsochrobactrum ovis gen. nov., sp. nov., isolated from a sheep

A Gram-stain-negative, rod-shaped, oxidase-positive, non-spore-forming, non-motile bacterium (B1315(T)) was isolated from the placenta of a sheep with abortion. On the basis of 16S rRNA gene sequence analyses the strain was assigned to the Brucella-Ochrobactrum-Paenochrobactrum-Pseudochrobactrum group with 94.5-94.8 %, 94.3-96.1 %, 95.0-95.1 %, and 95.9-96.1 % sequence similarities to type strains of species of the four genera, respectively. Phylogenetic trees indicated a close relationship to the type strains of Ochrobactrum gallinifaecis and Ochrobactrum oryzae (95.9 and 96.1 % sequence similarity, respectively). Chemotaxonomic data confirmed the allocation of strain B1315(T) to the family Brucellaceae (quinone system: ubiquinone Q-10 and major fatty acids: C18 : 1ω7c and C19 : 0 cyclo ω8c). The polar lipid profile contained the major lipids diphosphatidylglycerol, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and the unidentified but unique phospholipid PL7. The polyamine pattern of strain B1315(T) contained the major polyamines spermidine and putrescine. On the basis of the 16S rRNA gene and recA sequence phylogeny and chemotaxonomic data strain B1315(T) was clearly different from the genera Brucella, Ochrobactrum, Paenochrobactrum and Pseudochrobactrum. On the basis of these data we propose the novel genus Falsochrobactrum gen. nov. with the type species Falsochrobactrum ovis sp. nov. with the type strain B1315(T) ( = CCM 8460(T) = LMG 27356(T.)) The taxonomic allocation of O. gallinifaecis, which grouped inconsistently together with strain B1315(T) on the basis of 16S rRNA gene sequence data, but shows the chemotaxonomic features of the genus Ochrobactrum, remains to be clarified.

Effect of high-dose nano-selenium and selenium-yeast on feed digestibility, rumen fermentation, and purine derivatives in sheep

The aim of this study was to evaluate the effect of nano-selenium (NS) and yeast-selenium (YS) supplementation on feed digestibility, rumen fermentation, and urinary purine derivatives in sheep. Six male ruminally cannulated sheep, average 43.32 ± 4.8 kg of BW, were used in a replicated 3 × 3 Latin square experiment. The treatments were control (without NS and YS), NS with 4 g nano-Se (provide 4 mg Se), and YS with 4 g Se-yeast (provide 4 mg Se) per kilogram of diet dry matter (DM), respectively. Experimental periods were 25 days with 15 days of adaptation and 10 days of sampling. Ruminal pH, ammonia N concentration, molar proportion of propionate, and ratio of acetate to propionate were decreased (P < 0.01), and total ruminal VFA concentration was increased with NS and YS supplementation (P < 0.01). In situ ruminal neutral detergent fiber (aNDF) degradation of Leymus chinensis (P < 0.01) and crude protein (CP) of soybean meal (P < 0.01) were significantly improved by Se supplementation. Digestibilities of DM, organic matter, crude protein, ether extract, aNDF, and ADF in the total tract and urinary excretion of purine derivatives were also affected by feeding Se supplementation diets (P < 0.01). Ruminal fermentation was improved by feeding NS, and feed conversion efficiency was also increased compared with YS (P < 0.01). We concluded that nano-Se can be used as a preferentially available selenium source in ruminant nutrition.

Methanogen colonisation does not significantly alter acetogen diversity in lambs isolated 17 h after birth and raised aseptically

Reductive acetogenesis is not competitive with methanogenesis in adult ruminants, whereas acetogenic bacteria are the dominant hydrogenotrophs in the early rumen microbiota. The ecology of hydrogenotrophs in the developing rumen was investigated using young lambs, raised in sterile isolators, and conventional adult sheep. Two lambs were born naturally, left with their dams for 17 h and then placed into a sterile isolator and reared aseptically. They were inoculated with cellulolytic bacteria and later with Methanobrevibacter sp. 87.7 to investigate the effect of methanogen establishment on the rumen acetogen population since they lacked cultivable representatives of methanogens. Putative acetogens were investigated by acetyl-CoA synthase and formyltetrahydrofolate synthetase gene analysis and methanogens by methyl coenzyme reductase A gene analysis. Unexpectedly, a low abundant but diverse population of methanogens (predominantly Methanobrevibacter spp.) was identified in isolated lambs pre-inoculation with Mbb. sp 87.7, which was similar to the community structure in conventional sheep. In contrast, potential acetogen diversity in isolated lambs and conventional sheep was different. Potential acetogens affiliated between the Lachnospiraceae and Clostridiaceae in conventional sheep and with the Blautia genus and the Lachnospiraceae in isolated lambs. The establishment of Mbb. sp. 87.7 (1,000-fold increase in methanogens) did not substantially affect acetogen diversity.

Representative seroprevalences of brucellosis in humans and livestock in Kyrgyzstan

Kyrgyzstan reported 77.5 new human brucellosis cases per 100,000 people in 2007, which is one of the highest incidences worldwide. In Kyrgyzstan, the currently used diagnostic tests in humans and animals are the Rose Bengal Test and the Huddleson test. A national representative cross-sectional study using cluster sampling proportional to size in humans, cattle, sheep, and goats was undertaken to assess the apparent seroprevalence in humans and animals. A total of 4,936 livestock sera and 1,774 human sera were tested in Naryn, Chuy, and Osh Oblasts. The overall apparent seroprevalences of brucellosis were 8.8% in humans (95% CI 4.5-16.5), 2.8% (95% CI 1.6-4.9%) in cattle, 3.3% (95% CI 1.5-6.9%) in sheep, and 2.5% (95% CI 1.4-4.5%) in goats. Naryn Oblast had the highest seroprevalences in humans and sheep. More men than women were seropositive (OR = 1.96; P < 0.001). Human seroprevalence was significantly associated with small ruminant seroprevalence but not with cattle seroprevalence. Annual incidence of human brucellosis exposure, measured by serological tests, was more than ten times higher than the annual incidence of reported clinical brucellosis cases. This indicates an under-reporting of human brucellosis cases, even if only a fraction of seropositive people have clinical symptoms. In conclusion, this study confirms the high seroprevalence of brucellosis in Kyrgyzstan and warrants rapid effective intervention, among others, by mass vaccination of sheep and goats but also of cattle.

Staphylococcus aureus proteins differentially recognized by the ovine immune response in mastitis or nasal carriage

Staphylococcus aureus is an opportunistic pathogen in dairy ruminants where it is found in healthy carriage and can be a major cause of mastitis. A better knowledge of the host-pathogen interactions is needed to tackle this serious animal health problem. This study aimed at identifying S. aureus proteins differentially expressed by S. aureus in nasal colonization versus mastitis. Serological proteome analysis (SERPA) was used to examine protein samples prepared from culture supernatants of S. aureus strains originally isolated from gangrenous mastitis and nasal carriage (O11) or subclinical mastitis (O46) and to compare patterns of immune-reactive proteins. These staphylococcal proteins were revealed by sera obtained from ewes suffering from S. aureus mastitis and by sera obtained from healthy nulliparous ewes (i.e. no lactation and no mastitis or other symptoms) that were nasally colonized by S. aureus. Altogether 49 staphylococcal immune-reactive proteins were identified in this study. Patterns of proteins revealed by sera from infected- or healthy carrier- animals were comparable and analysis singled out one immune-reactive protein, N-acetylmuramyl-L-alanine amidase, which was recognized by each of the 6 sera from infected animals, when tested individually, and not by the sera of healthy carriers. This is the first study that compares the S. aureus seroproteome in colonization versus mastitis context in ruminants. These results open avenues for studies aiming at a better understanding of the balance between infection and commensal lifestyle in this opportunistic pathogen and at new prevention strategies.

Effects of Euphorbia esula L. (leafy spurge) on cattle and sheep in vitro fermentation and gas production

BACKGROUND

Euphorbia esula L. (leafy spurge) is indigenous to Eurasia and has been known to cause grazing aversion in ruminant species. As a result, E. esula encroachment has negatively impacted rangelands in the Northern Great Plains and Intermountain West of the USA, as well as southern Canada. Our objectives were to evaluate the effect of increasing concentrations of E. esula on in vitro dry matter digestibility (DMD) and gas production. Two ruminally-cannulated cows and ewes were used as rumen inoculum donors. To accomplish objectives, two studies were conducted. In study 1, animals were fed exclusively a barley hay (12% crude protein (CP), 55.4% neutral detergent fiber (NDF), DM basis) diet; whereas in study 2, animals were fed a diet of 15% E. esula (21.9% CP, 48% NDF, DM basis) and 85% barley hay based on previous day intake.

RESULTS

The 24 and 48 h in vitro and 96 h gas production indicate that, regardless of inoculum source or substrate fermented, DMD was not influenced. Differences, however, were consistently observed across studies for NDF disappearance.

CONCLUSION

Regardless of inoculum source NDF disappearance was greater when substrate being fermented contained 0%, 80%, or 100% E. esula.

Microbial protein synthesis, nitrogen capture efficiency and nutrient utilisation in sheep fed on finger millet straw (Eleucine coracana)-based diet with different rumen-degradable nitrogen levels

BACKGROUND

Microbial protein synthesised in the rumen is a very important protein source for ruminants. It is essential to provide an adequate amount of rumen-degradable nitrogen (RDN) for optimum microbial protein synthesis in the rumen on straw-based diets. The objective of this study was to determine the RDN requirement for optimum microbial protein synthesis (MPS), nitrogen capture efficiency (NCE) and nutrient utilisation in Nellore rams fed on a finger millet straw (FMS)-based diet.

RESULTS

Thirty-six Nellore sheep were randomly divided into four groups of nine animals each using a balanced, completely randomised design. The animals in group 1 (RDN0) were fed with ad libitum FMS. Those in groups 2, 3 and 4 (RDN1, RDN2 and RDN3) were supplemented with groundnut cake to provide RDN levels of 14, 18 and 23 g RDN kg⁻¹ digestible organic matter intake (DOMI) or 21, 27 and 35 g RDN kg⁻¹ digestible organic matter apparently digested in the rumen (DOMR) respectively along with FMS. The digestibility coefficients of all nutrients and MPS increased (P < 0.05) quadratically with increasing level of RDN supplementation. NCE decreased linearly (P < 0.05) as the level of RDN increased.

CONCLUSION

The results suggest that 12 g RDN kg⁻¹ DOMI or 19 g RDN kg⁻¹ DOMR may be adequate for optimum MPS, NCE and digestibility of nutrients in sheep fed on an FMS-based diet.

[Epidemiological investigation of Shiga toxin-producing Escherichia coli isolates originated from healthy sheep in one farm of Jiangsu Province and their pathogenicity]

OBJECTIVE

In order to investigate the distribution of Shiga toxin-producing Escherichia coli (STEC) among healthy sheep in a farm and the pathogenicity to mice and Vero cells of these STEC isolates.

METHODS

We used polymerase chain reaction (PCR) to detect genes of eaeA, stx1, stx2, hlyA, which had been developed in this laboratory previously, combing the selective cultivation and Chrom-Agar (CA) O157 plates to isolate STEC strains.

RESULTS

A total of 107 STEC strains were isolated in a sheep farm during six visits from August, 2008 to January, 2009. The isolation rate was 19.8% (107/550). These isolates belonged to 41 O serotypes and 60 O: H serotypes, except that 21 were O non-typable and 1 was rough. 093 was the common serotype. Some isolates such as O5, O91, O103, which are reported in other countries originated from healthy sheep were also isolated in this study. Stx2 positive rate was higher than that of stxl. 50% lethal dose assay in mice indicated the pathogenicity of isolates was low and none of the 3 tested isolates caused mice death. We selected 107 stx gene positive STEC strains to induce the lambdoid bacteriophages. The results showed that 71 out of 107 isolates formed plagues, while 28 did not after induction. Detection of Shiga toxins for three tested isolates in Vero cell assay indicated one stx gene positive strain lacked the toxigenicity to Vero cells.

CONCLUSIONS

Sheep are the natural reservoirs of STEC and they are healthy to carry STEC. Although these STEC isolates experience low pathogenicity to mice, they are potential threat to human health. Shiga toxin gene positive were not equal to production of Shiga toxins, so we need to further study the Shiga toxin expression and regulation mechanism.

Detection and frequency of Stx2 gene in Escherichia coli O157 and O157:H7 strains isolated from sheep carcasses in Shiraz-Iran

Enterohaemorrhagic Escherichia coli constitute a subset of serotypes (E. coli O157 and some other serogroups) of Shiga toxin-producing E. coli firmly associated with severe human illnesses like bloody diarrhoea and haemolytic uraemic syndrome. Escherichia coli O157:H7 is a zoonotic pathogen. They rarely cause disease in animals, live in the intestines of healthy sheep and ruminants are recognized as their main natural reservoir, so they can contaminate meat during slaughtering practices. The purpose of this study was epidemiological survey on the occurrence of E. coli O157:H7 in healthy sheep in Shiraz-Iran. Polymerase Chain Reaction (PCR) assay was developed to detect the Stx2 gene the only bacterial factor that has been associated with more severe disease. During a period of 7 months (December 2005 to June 2006), 153 slaughtered sheep at Shiraz slaughterhouse, were randomly selected and examined for surface carriage of E. coli O157:H7 by conventional plating and Stx2 gene detection by PCR technique. E. coli O157:H7 was found in 6(3.92%) of 153 sheep. The bacteria were isolated from 5(3.34%) of 114 and 1(2.63%) of 38 sheep two or under two and more than 2 years old, respectively (p = 0.5). The contamination rate might vary depending on season, age and infection time. The higher frequency for younger animals may be due to differences in the composition of the gastrointestinal flora resulting from differences in diet. This is the first report of the presence of E. coli O157:H7 in sheep from Iran.

Prevalence and distribution of Arcobacter species in various sources in Turkey and molecular analysis of isolated strains by ERIC-PCR

AIMS

To determine the prevalence of Arcobacter in various food, animal and water sources in Turkey and to subtype the isolated strains using enterobacterial repetitive intergenic consensus (ERIC)-PCR.

METHODS AND RESULTS

A total of 806 samples consisting of chicken (100) and turkey meat (100); minced beef (27); rectal swabs from cattle (173), sheep (68) and dogs (62); cloacal swabs of broilers (100) and layers (100); gall bladders of cattle (50) and drinking water samples (26) were examined. A previously described membrane filtration method was used for the isolation. Isolates were identified at species level using multiplex-PCR and discriminated by ERIC-PCR for subtyping. Ninety-eight (12.1%) of the samples examined were found positive for arcobacters. Arcobacter spp. were isolated from 68%, 4%, 6.9%, 8% and 37% of chicken and turkey meats, rectal swabs and gall bladders of cattle and minced beef, respectively. No arcobacters were obtained from the rectal swabs of sheep and dogs, cloacal swabs of broilers and layers, and water samples examined. In total, 99 Arcobacter isolates were obtained. Of these isolates, 92 were identified as Arcobacter butzleri, five were Arcobacter skirrowii and two were Arcobacter cryaerophilus. Thirteen distinct DNA profiles among A. butzleri isolates were obtained by the ERIC-PCR. Of these profiles, eight were from chicken carcass, three from cattle rectal swab and two from minced beef meat isolates. Some of the isolates originated from different sources gave the same DNA profiles. All isolates of A. skirrowii and A. cryaerophilus gave different DNA profiles.

CONCLUSIONS

Poultry carcasses, minced beef meat, rectal swabs and gall bladders of cattle were found to be positive for Arcobacter spp. A. butzleri was the predominant species isolated. In addition, large heterogeneity among the Arcobacter isolates was determined.

SIGNIFICANCE AND IMPACT OF THE STUDY

Contamination of the poultry carcasses and minced beef meat, rectal and gall bladder samples of cattle with arcobacters poses a risk for both human and animal infections. Detection of several different Arcobacter strains may suggest multiple sources for contamination and infection.

Establishment and development of ruminal hydrogenotrophs in methanogen-free lambs

The aim of this work was to determine whether reductive acetogenesis can provide an alternative to methanogenesis in the rumen. Gnotobiotic lambs were inoculated with a functional rumen microbiota lacking methanogens and reared to maturity on a fibrous diet. Lambs with a methanogen-free rumen grew well, and the feed intake and ruminal volatile fatty acid concentrations for lambs lacking ruminal methanogens were lower but not markedly dissimilar from those for conventional lambs reared on the same diet. A high population density (10(7) to 10(8) cells g(-1)) of ruminal acetogens slowly developed in methanogen-free lambs. Sulfate- and fumarate-reducing bacteria were present, but their population densities were highly variable. In methanogen-free lambs, the hydrogen capture from fermentation was low (28 to 46%) in comparison with that in lambs containing ruminal methanogens (>90%). Reductive acetogenesis was not a significant part of ruminal fermentation in conventional lambs but contributed 21 to 25% to the fermentation in methanogen-free meroxenic animals. Ruminal H(2) utilization was lower in lambs lacking ruminal methanogens, but when a methanogen-free lamb was inoculated with a methanogen, the ruminal H(2) utilization was similar to that in conventional lambs. H(2) utilization in lambs containing a normal ruminal microflora was age dependent and increased with the animal age. The animal age effect was less marked in lambs lacking ruminal methanogens. Addition of fumarate to rumen contents from methanogen-free lambs increased H(2) utilization. These findings provide the first evidence from animal studies that reductive acetogens can sustain a functional rumen and replace methanogens as a sink for H(2) in the rumen.

Presence of Shiga toxin-producing E. coli O157:H7 in a survey of wild artiodactyls

This study was carried out to evaluate the role of wild artiodactyls as reservoirs of Escherichia coli O157:H7 for livestock and humans. Retroanal mucosal swabs samples from 206 red deer (Cervus elaphus), 20 roe deer (Capreolus capreolus), 6 fallow deer (Dama dama) and 11 mouflon (Ovis musimon), collected during the hunting season (autumn-winter) in South-western Spain, were screened. Samples were pre-enriched in modified buffered peptone water, concentrated by an immunomagnetic separation technique and cultured onto selective cefixime tellurite sorbitol MacConkey agar. Polymerase chain reaction (PCR) was used to detect the presence of genes coding O157 and H7 antigens and the virulence factors verocytotoxin, intimin and enterohaemolysin. Three E. coli O157:H7 isolates were obtained from red deer (1.5%). Two of them showed inability to ferment sorbitol and lack of beta-d-glucuronidase (GUD) activity, however, the other strain investigated was an atypical sorbitol-fermenting E. coli O157:H7 with GUD(+) activity. This is the first report pointing to red deer as a reservoir of E. coli O157:H7 in Spain.

Conventional and real-time polymerase chain reaction assessment of the fate of transgenic DNA in sheep fed Roundup Ready rapeseed meal

Conventional and real-time PCR were used to detect transgenic DNA in digesta, faeces and blood collected from six ruminally and duodenally cannulated sheep fed forage-based (F) or concentrate-based (C) diets containing 15% Roundup Ready (RR) rapeseed meal (n 3). The sheep were adapted for 14 d to F or C diets containing non-GM rapeseed, then fed the RR diets for 11 d. On day 12, they were switched back to non-GM diets for a further 11 d. Ruminal and duodenal fluids (RF, DF) and faecal samples were collected at 3 or 4 h intervals over the 4 d immediately following the last feeding of GM diets. DNA was isolated from whole RF and DF, from the cell-free supernatant fraction, and from culture fermentation liquid. Blood was collected on days 1, 5 and 9 of feeding the RR rapeseed meal. The 1363 bp 5-enolpyruvylshikimate-3-phosphate synthase transgene (epsps) was quantifiable in whole RF and DF for up to 13 h, and a 108 bp epsps fragment for up to 29 h. Transgenic DNA was not detectable in faeces or blood, or in microbial DNA. Diet type (F v. C) did not affect (P>0.05) the quantity of transgenic DNA in digesta. More (P<0.05) transgenic DNA was detected in RF than in DF, but there was an interaction (P<0.05) between sample type and collection time. In supernatant fractions from RF and DF, three different fragments of transgenic DNA ranging in size from 62 to 420 bp were not amplifiable.

Molecular identification of methanogenic archaea from sheep in Queensland, Australia reveal more uncultured novel archaea

Molecular diversity of rumen methanogens in sheep in Queensland, Australia was investigated using 16S rRNA gene libraries prepared from pooled rumen contents from nine merino sheep. A total of 78 clones were identified revealing 26 different sequences. Of these 26 sequences, eight sequences (15 clones) were 95-100% similar to cultivated methanogens belonging to the orders Methanobacteriales and Methanomicrobiales, and the remaining 18 phylotypes (63 clones) were 72-75% similar to Thermoplasma acidophilum and Thermoplasma volcanium. These unique sequences clustered within a distinct and strongly supported (100% bootstrap support) phylogenetic group, exclusively composed of sequences from uncharacterized archaea from very diverse anaerobic environments. Members of this unique group that were previously considered atypical for the rumen environment were the predominant clones.

Detection and quantification of Shiga toxin-encoding genes in sheep faeces by real-time PCR

Sheep faeces may be an important source of Shiga toxin (Stx)-producing Escherichia coli. We have, therefore, established and evaluated a real-time 5'-nuclease PCR assay to quantify the stx(1) and stx(2) genes in sheep faeces. The detection limit of our assay for both stx(1) and stx(2) in spiked samples corresponded to 10(2)--10(3)CFU/g, which is lower than for other assays for measuring these genes in faecal samples. Quantification values for our assay ranged from 10(2) to 10(7)CFU/g faeces. The assay was evaluated on native, un-spiked faeces. All sheep tested (n=7) shed stx(1), and the quantitative results corresponded to the gene copies in 10(3)--10(4)CFU/g. The level of stx(2), however, was below the quantitative detection limit in all the samples analyzed. This quantitative stx(1) and stx(2) assay may be important in assessing whether sheep harbouring Shiga toxin-producing bacteria represent a potential hazard to human health.

Seasonal dynamics of antibiotic-resistantEnterobacteriaceae in the gastrointestinal tract of domestic sheep

Considerable variation in counts of antibiotic-resistant enterobacteria in the ovine gastrointestinal tract was observed. The occurrence of ruminal and fecal isolates resistant to ampicillin (Ap), kanamycin (Km) and tetracycline (Tc) culminated in summer months, followed by rapid decline in subsequent months. Using PCR the tem1bla (Apr), aphA1 (Kmr) and tetB (Tcr) genes were found to be predominant. Under in vitro conditions all resistance genes were transferable into laboratory Escherichia coli strain with relatively high frequency (10(-3) transconjugants per recipient).

Molecular detection and characterization of Dichelobacter nodosus in ovine footrot in India

Dichelobacter nodosus was detected in three clinical cases of ovine footrot in Kashmir, India. The detection was done by PCR in three clinical specimens directly, without isolating the organism, using species-specific 16S rDNA primers. Positive results were indicated by amplification of a 783 bp product. All the three samples were subjected to serogrouping by multiplex PCR using group (A-I) specific primers. All the three samples revealed the presence of serogroup B of D. nodosus by yielding a single band of 283 bps.

Evaluation of a modified Rose Bengal test and an indirect enzyme-linked immunosorbent assay for the diagnosis of Brucella melitensis infection in sheep

A modified Rose Bengal test (mRB) and an indirect ELISA (iELISA) with Protein G as the conjugate, were evaluated for the diagnosis of Brucella melitensis infection in unvaccinated sheep with a known bacteriological status, and their diagnostic efficacy was compared with that of the standard Rose Bengal (RB) and Complement Fixation (CF) tests used in the current eradication campaign in EU countries. All tests showed 100% specificity when testing the sera from 212 Brucella-free sheep. When testing the sera from 219 Brucella melitensis culture-positive sheep, both the mRB and iELISA tests were more sensitive (98.6% and 96.8%, respectively) than the RB and CF tests (95.0% and 92.7%, respectively). These results were similar when testing the sera from 181 animals belonging to infected flocks but found bacteriologically negative, suggesting that the mRB or iELISA tests could advantageously replace the current RB procedure used as the screening test.

Comparison of four techniques for the detection of Clostridium perfringens type D epsilon toxin in intestinal contents and other body fluids of sheep and goats

Polyclonal capture enzyme-linked immunosorbent assay (PC-ELISA), monoclonal capture ELISA (MC-ELISA), mouse neutralization test (MNT), and counterimmunoelectrophoresis (CIEP), were compared for their ability to detect epsilon toxin in intestinal contents and body fluids of sheep and goats. When used to evaluate intestinal contents of sheep artificially spiked with epsilon prototoxin, PC-ELISA detected 0.075 mouse lethal dose (MLD)50/ml, whereas the MNT, MC-ELISA, and CIEP detected 6, 25, and 50 MLD50/ml, respectively. Amounts of epsilon toxin detected by PC-ELISA, MC-ELISA, MNT, and CIEP in sheep pericardial fluid artificially spiked with epsilon prototoxin were 0.075, 0.75, 6, and 200 MLD50/ml, respectively. For assaying epsilon toxin in aqueous humor, PC-ELISA and MC-ELISA detected 0.075 MLD50/ml, whereas CIEP detected 200 MLD50/ml (MNT was not evaluated). When 51 samples of intestinal contents of sheep and goats (32 positive and 19 negative to MNT) were analyzed by the other 3 techniques, the relative sensitivity of PC-ELISA, MC-ELISA, and CIEP was 93.75, 84.37, and 37.50%, respectively. The specificity of PC-ELISA, MC-ELISA, and CIEP was 31.57, 57.89, and 84.21%, respectively. The absolute sensitivity of PC-ELISA, MC-ELISA, CIEP, and MNT was 90.90, 69.69, 15.15, and 54.54%. The absolute specificity of the 4 techniques was 100%. These results show that there is a marked inconsistency among techniques routinely used to detect Clostridium perfringens epsilon toxin. Until more consistent results are achieved, the diagnosis of enterotoxemia should not only be based solely on epsilon toxin detection, but also on clinical and pathological data.

Preparation of Ehrlichia ruminantium challenge material for quantifiable and reproducible challenge in mice and sheep

The causative agent of heartwater, Ehrlichia ruminantium, is a tick-transmitted pathogen that infects bovine endothelial cells. Due to the obligate intracellular nature of this organism obtaining pure material in sufficient quantities for challenge studies is difficult. A murine model is frequently used to study potential vaccine candidates but giving reproducible challenges in this model for heartwater has always been problematic. We have therefore performed a series of experiments to optimize the parameters governing the reproducibility of challenge material. Two cryoprotectants were compared for the preparation of challenge material, buffered lactose peptone (BLP) and sucrose-potassium-glutamate (SPG). In addition two sources of virulent E. ruminantium were used, infected bovine endothelial cultures and infected mouse spleen homogenates. We also examined practical parameters affecting the reproducibility of challenge experiments: the time it takes to deliver the challenge material, the length of time a mouse remains immune to E. ruminantium challenge, and the effect of a given challenge dose. Finally, we performed a pilot study to determine whether mice could be used to titrate challenge material to be used for experiments in sheep. We found that: (a) E. ruminantium-infected mouse spleen homogenate provides more reproducible challenges than tissue culture material; (b) SPG is a better cryoprotectant than BLP; (c) challenge material should be used within 20min of thawing; (d) it is not essential to use syngeneic material for murine challenge experiments; (e) Balb/c mice are more sensitive to E. ruminantium challenge than C57BL/6J mice; (f) mice immunized by infection and treatment for use as positive immune controls should be challenged within 3 months of immunization; and (g) mice should be challenged with a dose not exceeding 10 LD(50)s.

Evaluation of a new immunocapture test for the diagnosis of ovine brucellosis caused by Brucella melitensis

A new immunocapture technique has been applied to the diagnosis of ovine brucellosis under experimental conditions. The tests were made on a serum bank derived from both young and adult ewes vaccinated conjunctivally with the Rev 1 strain at a dose of 10(8) to 10(9) colony-forming units. Adult ewes were infected experimentally two-and-a-half years after they had been vaccinated and the results were compared with an unvaccinated control group. The condition of each animal in terms of infection with Brucella melitensis was determined by clinical and bacteriological investigations. The development of the immune response was compared by the rose bengal test, the complement fixation test, the Coombs' test and the immunocapture technique for 180 days after the vaccination and for 410 days after the experimental infection, that is, the two following gestations. The results suggest that the new technique is more specific in animals vaccinated conjunctivally, regardless of their age when they were vaccinated. After the experimental infection, significantly (P < 0.05) fewer of the vaccinated sheep which were free of clinical signs and were not excreting B melitensis reacted positively to the test.

Long-term excretion of Shiga toxin-producing Escherichia coli (STEC) and experimental infection of a sheep with O157

To investigate a long-term shedding of Shiga toxin (Stx)-producing Escherichia coli (STEC) from sheep, a fifteen-month study for STEC isolation from a sheep, which had yielded STEC before, was attempted. The sheep continued to shed STEC and 39 STEC were isolated. The number of STEC in the feces was estimated at 1.7 x 10(3) per gram. In addition, although Stx1-negative O157 and stx2-encoding bacteriophage were experimentally infected to the sheep, Stx-positive O157 or Stx2- producing bacterial cells were not detected. The genetical and biochemical characterization of those 39 STEC strains showed that all STEC strains produced Shiga toxin 1 (Stx1) and were divided into three classes (I to III). From phylogenetic analysis of their amino acid sequences, class-I STEC was classified as group 1 comprising mainly human STEC, and classes II/III were as group 2 comprising sheep STEC. Our results suggest that STEC easily colonized in sheep and that the sheep continued to shed STEC, showing that sheep might be an important reservoir for human STEC infection.