Use of contrast-enhanced ultrasonography in the diagnosis of a liver lobe torsion in a rabbit (Oryctolagus cuniculus).

A 1-year-old male French Lop rabbit (Oryctolagus cuniculus) was presented with a sudden onset of hyporexia. Physical examination revealed cranial abdominal discomfort. Liver enzymes were elevated on serum biochemistry profile. Abdominal radiographs showed diffusely gas-dilated small intestinal loops. On abdominal ultrasound, a lobe in the right aspect of the liver was hypoechoic with rounded margins and was surrounded by hyperechoic fat and anechoic fluid. Contrast-enhanced ultrasonography showed complete lack of perfusion in the abnormal right liver lobe. Exploratory laparotomy revealed torsion of the quadrate liver lobe. Diffuse coagulation necrosis was noted on histopathologic examination. The rabbit fully recovered after surgery.

Pharmacokinetics and absolute oral bioavailability of meloxicam in guinea pigs (Cavia porcellus).

OBJECTIVE: To investigate the pharmacokinetics and absolute oral bioavailability of meloxicam in guinea pigs. STUDY DESIGN: Prospective crossover study. ANIMALS: A group of six healthy male Dunkin Hartley guinea pigs. METHODS: A single dose of meloxicam (1.5 mg kg-1) was administered orally and intravenously (IV) to six healthy male guinea pigs. A wash-out period of 48 hours was taken into account between administrations (oral and IV) in the same animal. Blood was sampled through a central venous catheter before administration (t = 0 hours) and at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 20, 24 and 28 hours post administration. After centrifugation, plasma concentrations of meloxicam were measured by high-performance liquid chromatography with UV detection, and pharmacokinetic parameters were calculated using noncompartmental analysis. RESULTS: Meloxicam in guinea pigs exhibited a moderate absorption rate after oral dosing (time to maximal plasma concentration 3.7 ± 1.7 hours) and maximal plasma concentration was 0.92 ± 0.30 µg mL-1. After IV administration, total body clearance and volume of distribution were 0.13 ± 0.04 and 0.72 ± 0.36 L kg-1, respectively. Terminal half-life was 3.7 ± 0.7 hours and 3.5 ± 1.1 hours after IV and oral administration, respectively. Body extraction ratio was 0.0087 and mean absorption time was 3.8 ± 1.7 hours. The absolute oral bioavailability was 0.54 ± 0.14 in unfasted guinea pigs. CONCLUSIONS AND CLINICAL RELEVANCE: This study reported the pharmacokinetics of meloxicam in guinea pigs. Studies concerning efficacy and safety are the next step towards a rational use of this drug in guinea pigs.

High genetic diversity of methicillin-susceptible Staphylococcus aureus (MSSA) from humans and animals on livestock farms and presence of SCCmec remnant DNA in MSSA CC398.

OBJECTIVES: To investigate the genetic diversity of methicillin-susceptible Staphylococcus aureus (MSSA) carriage isolates from animals and humans on pig, veal, dairy, beef and broiler farms. METHODS: S. aureus isolates were genotyped using spa typing and multilocus sequence typing (MLST). Antimicrobial susceptibility phenotypes and genotypes were determined. The presence of staphylococcal cassette chromosome mec (SCCmec)-associated DNA was characterized by PCR and sequencing among isolates of clonal complex (CC) 398. RESULTS: Overall, 41 MSSA isolates in humans and 141 in animals were found, originating from all farm types. These MSSA were mainly assigned to CC398, CC1, CC5, CC9, CC30, CC97, CC133 and CC705/151. MSSA CC398 showed resistance to tetracycline, trimethoprim, macrolides and/or lincosamides, aminoglycosides, ciprofloxacin, spectinomycin and quinupristin/dalfopristin, whereas non-CC398 MSSA showed considerably less resistance. Three porcine MSSA CC398-t011 isolates harboured remnant DNA of a composite SCCmec V(5C2&5)c element that lacked the mec gene complex. This resulted from an MRSA-to-MSSA conversion due to recombination between the ccrC genes flanking the mec gene complex. The SCC remnant still contained an intact J1 region harbouring czrC and tet(K), encoding zinc and tetracycline resistance, respectively, thereby illustrating the capacity of S. aureus CC398 to adapt to different antibiotic selection pressures in the farming environment. Processes such as mec gene complex deletion probably contribute to the enormous diversity of SCC(mec) elements observed in staphylococci. CONCLUSIONS: MSSA CC398 precursors from which MRSA CC398 might (re)emerge were present on pig, veal and broiler farms, all of which are livestock sectors commonly known to be affected by MRSA CC398. The multiresistance phenotype of S. aureus CC398 appears to be independent of methicillin resistance.

Romulus and Remus, two phage isolates representing a distinct clade within the Twortlikevirus genus, display suitable properties for phage therapy applications.

The renewed interest in controlling Staphylococcus aureus infections using their natural enemies, bacteriophages, has led to the isolation of a limited number of virulent phages so far. These phages are all members of the Twortlikevirus, displaying little variance. We present two novel closely related (95.9% DNA homology) lytic myoviruses, Romulus and Remus, with double-stranded DNA (dsDNA) genomes of 131,333 bp and 134,643 bp, respectively. Despite their relatedness to Staphylococcus phages K, G1, ISP, and Twort and Listeria phages A511 and P100, Romulus and Remus can be proposed as isolates of a new species within the Twortlikevirus genus. A distinguishing feature for these phage genomes is the unique distribution of group I introns compared to that in other staphylococcal myoviruses. In addition, a hedgehog/intein domain was found within their DNA polymerase genes, and an insertion sequence-encoded transposase exhibits splicing behavior and produces a functional portal protein. From a phage therapy application perspective, Romulus and Remus infected approximately 70% of the tested S. aureus isolates and displayed promising lytic activity against these isolates. Furthermore, both phages showed a rapid initial adsorption and demonstrated biofilm-degrading capacity in a proof-of-concept experiment.

Characterization of methicillin-resistant non-Staphylococcus aureus staphylococci carriage isolates from different bovine populations.

OBJECTIVES: This study aimed at investigating bovine non-Staphylococcus aureus staphylococci for their role as a potential reservoir for methicillin resistance. METHODS: Nasal swab samples were collected from 150 veal calves on 15 veal farms, 100 dairy cows on 10 dairy farms and 100 beef cows on 10 beef farms. Suspected staphylococcal isolates were investigated by PCR for the presence of the classic mecA and mecA(LGA251). Methicillin-resistant non-S. aureus staphylococci (MRNAS) were genotypically identified and were characterized by broth microdilution antimicrobial susceptibility testing and staphylococcal cassette chromosome mec (SCCmec) typing. RESULTS: The MRNAS (n = 101) carriage rate was estimated as 30.29% (95% CI 6.14%-74.28%) in veal calves, 13.1% (95% CI 1.28%-63.72%) in dairy cows and 24.8% (95% CI 11.97%-44.42%) in beef cows. Carriage rates were not significantly different between the three populations (P > 0.05). mecA(LGA251) was not detected. Most (n = 80) MRNAS were identified as Staphylococcus sciuri, Staphylococcus lentus or Staphylococcus fleurettii. Resistance to aminoglycosides, macrolide-lincosamide-streptogramin antimicrobials, tetracycline and ciprofloxacin was frequently detected. Two linezolid-resistant MRNAS from veal calves carried the multidrug-resistance gene cfr. SCCmec cassettes of type III predominated (n = 46); another 40 SCCmec cassettes harboured a class A mec complex without identifiable ccr complex; type IVa, type V and several other non-typeable cassettes were detected in low frequencies, especially in methicillin-resistant Staphylococcus epidermidis. CONCLUSIONS: The SCCmec types predominating in bovine MRNAS differ from those mostly detected in livestock-associated methicillin-resistant S. aureus strains. Yet, the detection of cfr and the high level of other antimicrobial resistances suggest a potentially important role of bovine MRNAS as a reservoir for resistance determinants other than SCCmec.

Prevalence, risk factors and genetic diversity of methicillin-resistant Staphylococcus aureus carried by humans and animals across livestock production sectors.

OBJECTIVES: This study aimed to assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in animals and humans on veal, dairy, beef and broiler farms and to compare the risk for human MRSA carriage with that of strictly horticulture farmers. The genetic background, resistance phenotypes and genotypes and toxin gene content of the isolated MRSA strains were compared with MRSA collected on MRSA clonal complex (CC)398-positive pig farms. METHODS: MRSA carriage isolates were genotyped (spa, SCCmec and multilocus sequence typing), resistance to 16 antimicrobials was determined and resistance and toxin genes were detected. RESULTS: MRSA carriage rates were higher (P<0.01) on veal farms (calves, 64%; farmers, 72%) compared with on dairy (cows, 1%), beef (cows, 5%; farmers, 11%), broiler (pooled broths, 5%; farmers, 3%) and horticulture (farmers, 3%) farms. The intensity of animal contact was identified as a risk factor for human MRSA carriage. The vast majority of MRSA (n=344), including those from pigs, were CC398 (98%). SCCmec V(5C2), V(5C2&5)c, IV(2B) and IV(2B&5) predominated. MRSA CC130 and CC599 carrying mecC were detected in beef and dairy cattle. MRSA from veal calves were significantly more resistant than MRSA from pigs (P<0.01). A few isolates, including mecC-carrying MRSA, harboured pyrogenic superantigen toxins. Human- and animal-derived MRSA from individual farms showed similar characteristics. CONCLUSIONS: This systematic cross-sector survey revealed a high prevalence of multiresistant livestock-associated MRSA on Belgian veal calf farms as compared with other farm types. MRSA harbouring mecC was detected at a low frequency in beef and dairy cows, but not in humans.

Serological profiles in nursery piglets colonized with Staphylococcus aureus.

At present, the immune response of pigs in relation to Staphylococcus aureus carriage is poorly understood. This study was aimed at investigating the dynamics of the anti-staphylococcal humoral immune response in methicillin-susceptible S. aureus (MSSA)-positive piglets and at assessing the effect of the experimental introduction of a methicillin-resistant S. aureus (MRSA) Sequence Type (ST) 398 strain. Therefore, serum samples were collected at different times from 31 weaned piglets originating from four different sows. Twenty-four out of the 31 piglets were challenged with MRSA ST398. The serum samples were analyzed for IgG antibodies to 39 S. aureus antigens, using a multiplex bead-based assay (xMAP technology, Luminex Corporation). Though antibody responses showed broad inter-individual variability, serological results appeared to be clustered by litter of origin. For most antigens, an age-related response was observed with an apparent increase in antibody titers directed against staphylococcal microbial surface components recognizing adhesive matrix molecules (MSCRAMM), which have been shown to play a role in S. aureus colonization. In most animals, antibody titers directed against staphylococcal toxins or immune-modulating proteins decreased with age, possibly reflecting the absence of bacterial invasion. The introduction of MRSA ST398 did not elicit a significant humoral immune reaction.This study describes, for the first time, the humoral immune response in weaned pigs colonized with S. aureus.

Fish as research tools: alternatives to in vivo experiments.

The use of fish in scientific research is increasing worldwide, due to both the rapid expansion of the fish farming industry and growing awareness of questions concerning the humane use of mammalian models in basic research and chemical testing. As fish are lower on the evolutionary scale than mammals, they are considered to be less sentient. Fish models are providing researchers, and those concerned with animal welfare, with opportunities for adhering to the Three Rs principles of refinement, reduction and replacement. However, it should be kept in mind that fish should also be covered by the principles of the Three Rs. Indeed, various studies have shown that fish are capable of nociception, and of experiencing pain in a manner analogous to that in mammals. Thus, emphasis needs to be placed on the development of alternatives that replace, as much as possible, the use of all living vertebrate animals, including fish. This review gives the first comprehensive and critical overview of the existing alternatives for live fish experimental studies. The alternative methods described range from cell and tissue cultures, organ and perfusion models, and embryonic models, to in silico computer and mathematical models. This article aspires to guide scientists in the adoption of the correct alternative methods in their research, and, whenever possible, to reduce the use of live fish.

Colonization and transmission of methicillin-resistant Staphylococcus aureus ST398 in nursery piglets.

A transmission experiment was performed to evaluate the spread of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in nursery piglets. Reproduction ratios (R(0)) in three experimental groups were found to vary between 3.92 and 52.54, indicating that after introduction, MRSA ST398 will spread easily among weaned piglets, with a tendency to become established.

Low MRSA prevalence in horses at farm level.

BACKGROUND: In Europe, methicillin-resistant Staphylococcus aureus (MRSA) belonging to the clonal complex (CC) 398 has become an important pathogen in horses, circulating in equine clinics and causing both colonization and infection. Whether equine MRSA is bound to hospitals or can also circulate in the general horse population is currently unknown. This study, therefore, reports the nasal and perianal MRSA screening of 189 horses on 10 farms in a suspected high prevalence region (East- and West-Flanders, Belgium). RESULTS: Only one horse (0.53%) from one farm (10%) tested positive in the nose. It carried a spa type t011-SCCmecV isolate, resistant to ß-lactams and tetracycline, which is typical for livestock-associated MRSA CC398. CONCLUSION: In the region tested here, horses on horse farms seem unlikely to substantially contribute to the large animal associated ST398 MRSA reservoir present at intensive animal production units.

Limited added value of negative pressure wound therapy compared with calcium alginate dressings for second intention healing in a noncontaminated and contaminated equine distal limb wound model.

BACKGROUND: Distal limb wounds in horses often show aberrant healing due to a slow inflammatory response. In human medicine, negative pressure wound therapy (NPWT) is used for the treatment of chronic wounds with a similar inflammatory response. OBJECTIVES: To compare the effect of NPWT to calcium alginate dressings on the healing of (non) contaminated equine distal limb wounds. STUDY DESIGN: Controlled experiment. METHODS: Circular wounds were created on the left and right dorsomedial metacarpus of 10 horses. In five horses, the wounds were contaminated with Staphylococcus aureus and Pseudomonas aeruginosa. In all horses, one limb was treated with NPWT, the other with calcium alginate dressings. Treatments were applied during nine days for noncontaminated wounds and six days for contaminated wounds. Noninvasive (clinical assessment, bacteriology swabs, thermographic images and wound dimensions) and invasive (biopsies for histology and growth factor analysis) measurements were taken regularly for 71 and 29 days respectively. Effects of selected parameters on continuous dependent variables were analysed using ANOVA, while for discrete dependent variables, logistic regression was applied. RESULTS: In noncontaminated wounds, there was significantly less wound retraction in the early healing stages when treated with NPWT (mean difference [95% CI] = 19.2% [13.3%-25.1%]; P = .005), although wound size was not significantly different between NPWT and control wounds at later healing stages. Noncontaminated control wounds had a significantly higher neutrophil influx (OR [95% CI] = 1.99 [1.49-2.66]; P < .001) and lower macrophage influx (OR [95% CI] = 0.75 [0.60-0.93]; P = .008) compared with NPWT-treated wounds. Bacterial load and the presence of growth factors did not differ between treatments in noncontaminated wounds. In contaminated wounds, no differences between treatments were observed in wound size, histological parameters, bacterial load or growth factor concentration. MAIN LIMITATIONS: Sample size is small. CONCLUSIONS: No long-term advantage was detected with NPWT compared with calcium alginate dressings in noncontaminated or contaminated equine distal limb wounds healing by second intention.

Flexor tendon repair using a reinforced tubular, medicated electrospun construct.

A reinforced tubular, medicated electrospun construct was developed for deep flexor tendon repair. This construct combines mechanical strength with the release of anti-inflammatory and anti-adhesion drugs. In this study, the reinforced construct was evaluated using a rabbit model. It was compared to its components (a tubular, medicated electrospun polymer without reinforcement and a tubular braid as such) on the one hand to a modified Kessler suture as a control group. Forty New Zealand rabbits were randomly divided into two groups. Surgery was performed in the second and fourth deep flexor tendons of one hind paw of the rabbits in the two groups using four repair techniques. Biomechanical tensile testing and macroscopic and histological evaluations were performed at 3 and 8 weeks postoperatively. A two-way analysis of variance with pairwise comparisons revealed that the three experimental surgical techniques (a reinforced tubular medicated electrospun construct, tubular-medicated construct, and tubular braid as such) showed similar strength as that of a modified Kessler suture repair, which was characterized by a mean load at ultimate failure of 19.85 N (standard deviation [SD] 5.29 N) at 3 weeks and 18.15 N (SD 8.01 N) at 8 weeks. Macroscopically, a significantly different adhesion pattern was observed at the suture knots, either centrally or peripherally, depending on the technique. Histologically, a qualitative assessment showed good to excellent repair at the tendon repair site, irrespective of the applied technique. This study demonstrates that mechanical and biological repair strategies for flexor tendon repair can be successfully combined.

The current status and future directions of myxoma virus, a master in immune evasion.

Myxoma virus (MYXV) gained importance throughout the twentieth century because of the use of the highly virulent Standard Laboratory Strain (SLS) by the Australian government in the attempt to control the feral Australian population of Oryctolagus cuniculus (European rabbit) and the subsequent illegal release of MYXV in Europe. In the European rabbit, MYXV causes a disease with an exceedingly high mortality rate, named myxomatosis, which is passively transmitted by biting arthropod vectors. MYXV still has a great impact on European rabbit populations around the world. In contrast, only a single cutaneous lesion, restricted to the point of inoculation, is seen in its natural long-term host, the South-American Sylvilagus brasiliensis and the North-American S. Bachmani. Apart from being detrimental for European rabbits, however, MYXV has also become of interest in human medicine in the last two decades for two reasons. Firstly, due to the strong immune suppressing effects of certain MYXV proteins, several secreted virus-encoded immunomodulators (e.g. Serp-1) are being developed to treat systemic inflammatory syndromes such as cardiovascular disease in humans. Secondly, due to the inherent ability of MYXV to infect a broad spectrum of human cancer cells, the live virus is also being developed as an oncolytic virotherapeutic to treat human cancer. In this review, an update will be given on the current status of MYXV in rabbits as well as its potential in human medicine in the twenty-first century.

Persecution of Birds of Prey in Flanders: A Retrospective Study 2011-19.

For decades birds of prey have been under the protection of European law, but deliberate or unintentional killing is still a large-scale problem in Europe. In an effort to monitor illegal practices, the Flemish government established several bird of prey hotlines in 2006. Since then, every suspicious death of a bird of prey has been investigated. This retrospective study reviews the necropsy results of every bird of prey submitted for investigation from January 2011 to December 2019, with a focus on illegal practices. In 36.7% (83/226) of all necropsy cases, an illegal cause of death was found, with poisoning being demonstrated in 88% (73/83) of these cases. Cholinesterase inhibitors were the most commonly used toxins, despite being prohibited in Europe. With a prevalence of 82.5% (260/315) of all cases, the Common Buzzard (Buteo buteo) was the species most submitted for necropsy.

Computed tomography and cross-sectional anatomy of the head in healthy rabbits.

OBJECTIVE: To obtain a detailed anatomic description of the rabbit head by means of computed tomography (CT). ANIMALS: 6 clinically normal Dendermonde White rabbits weighing 3 kg and raised for human consumption and 1 Netherland dwarf rabbit. PROCEDURES: The commercially raised rabbits were slaughtered in a slaughterhouse, flayed, and decapitated. The dwarf rabbit was euthanatized. Two hours later, each rabbit head was positioned with the ventral side on the CT table to obtain transverse and sagittal, 1-mm-thick slices. Dorsal images were obtained by placing each head perpendicular to the table. Immediately after the CT examination, 3 heads were frozen in an ice cube at -14 degrees C until solid and then sectioned at 4-mm-thick intervals by use of an electric band saw. Slab sections were immediately cleaned, photographed, and compared with corresponding CT images. Anatomic sections were examined, and identified anatomic structures were matched with structures on corresponding CT images. RESULTS: The bone-window CT images yielded good anatomic detail of the dentition and the bony structures of rabbit skulls. The soft tissue structures that could be determined were not better identifiable on the soft tissue-window CT images than on the bone-window images. CONCLUSIONS AND CLINICAL RELEVANCE: CT images of the heads of healthy rabbits yielded detailed information on the skull and some surrounding soft tissue structures. Results of this study could be used as a guide for evaluation of CT images of rabbits with various cranial and dental disorders.

Methicillin-resistant Staphylococcus aureus in poultry.

Methicillin-resistant Staphylococcus aureus (MRSA) has been detected in several species and animal-derived products. To determine whether MRSA is present in poultry, we sampled 50 laying hens and 75 broiler chickens. MRSA was found in some broiler chickens but no laying hens. In all samples, spa type t1456 was found.

Screening of genes encoding adhesion factors and biofilm formation in Staphylococcus aureus isolates from poultry.

Staphylococcus aureus isolates recovered from poultry between 1970 and 1972 (90 old isolates) and in 2006 (81 recent isolates) were screened for the presence of bap, icaA and icaD genes associated with biofilm formation, and for bbp, cna, ebpS, eno, fib, fnbA, fnbB, clfA and clfB genes that encode microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). Most of the old isolates were collected from broiler breeders affected by staphylococcal tenosynovitis and arthritis, whilst nearly all recent isolates were derived from the nose and cloaca of healthy broilers. Ten recent isolates belonged to the animal-associated methicillin-resistant S. aureus (MRSA) ST398. All isolates were positive for clfA, clfB, eno and fnbA, and were negative for bap and bbp. All recent isolates were also positive for ebpS and cna, and all old isolates were positive for fib. The average number of genes encoding adhesins and biofilm-associated proteins in both groups was eight per isolate. All MRSA ST398 isolates in this study were positive for icaD, cna, ebpS, eno, fnbA, fnbB, clfA and clfB. No relevant differences were found between the presence of adhesin and biofilm formation genes in old and recent S. aureus isolates or in isolates from healthy compared with diseased chickens. From this study, there is no indication that the presence of these genes has changed over time and no specific association could be found between the presence of certain MSCRAMM or biofilm genes in poultry S. aureus isolates and the isolate's capacity to cause disease.

Antimicrobial resistance of old and recent Staphylococcus aureus isolates from poultry: first detection of livestock-associated methicillin-resistant strain ST398.

The susceptibilities of 12 antimicrobial agents for two collections of Staphylococcus aureus, isolated in the 1970s and in 2006 from poultry, were determined. For eight antibiotics, the percentage of resistance was significantly higher in the recent isolates. Ten recent isolates were methicillin resistant and had spa types t011 and t567, belonging to multilocus sequence type 398. This is the first report of "livestock-associated" methicillin resistant S. aureus from healthy poultry.

First report of a mycolactone-producing Mycobacterium infection in fish agriculture in Belgium.

In the past few years, a mycolactone-producing subgroup of the Mycobacterium marinum complex has been identified and analyzed. These IS2404-positive species cause pathology in frogs and fish. A recently isolated mycobacterial strain from a fish in Belgium was analyzed using a variety of molecular methods and the results were identical to those obtained from a mycolactone-producing M. marinum from Israel.

Multiplex PCR assay for the detection of high virulence rabbit Staphylococcus aureus strains.

High virulence rabbit Staphylococcus aureus strains, which are clonal in origin, are responsible for the spread of chronic staphylococcosis at the rabbit flock level. The aim of the present study was to develop a multiplex PCR assay that can be used for the identification of these high virulence strains. Two targets of the assay were the bbp and the selm genes, which have recently been shown to occur specifically in high virulence isolates. A third target was a sequence designated "flank", which was derived from a previously generated high virulence specific RAPD pattern. Furthermore, the femA gene, which is specific for S. aureus, was incorporated in order to avoid false negative results due to insufficient DNA preparation. The multiplex PCR was successful at differentiating the 26 typical high virulence and 50 low virulence rabbit S. aureus strains incorporated in the present study. Therefore it is useful for the initial screening of newly acquired breeding stock, in order to prevent the intake of high virulence strains in rabbitries.