Ann Martens

High occurrence of methicillin-resistant Staphylococcus aureus ST398 in equine nasal samples

Methicillin-resistant Staphylococcus aureus (MRSA) infections do occur in equine patients. Little is known, however, about their origin and the general equine MRSA colonization status. In West European horses in particular, neither the colonization rate nor the present strains or their antimicrobial susceptibility patterns are known. In the present study, a sample of 110 (Belgian, French, Dutch and Luxemburg) horses presented at a Belgian equine clinic was screened for nasal MRSA carriage. An indirect culturing protocol using a 0.001% colistin and nalidixic acid containing broth was compared to a direct agar method. Phenotypic identification following growth on a chromogenic MRSA screening agar (ChromID MRSA) was combined with genotypic analysis (PCR, PFGE, SCCmec, spa, and MLST typing). Antimicrobial susceptibility was tested through disk diffusion. Twelve (10.9%) horses carried MRSA, with the enrichment protocol resulting in a significantly higher isolation rate. None of the isolated strains were typeable through SmaI PFGE. They all harboured SCCmec type IVa or V and belonged to spa type t011 or t1451 of the ST398 lineage. All isolates were tetracycline resistant and sulfonamide and enrofloxacin susceptible. Macrolide, lincosamide, trimethoprim and aminoglycoside susceptibility varied and in total five different antimicrobial resistance patterns were distinguished. These results show that ST398 is certainly present in West European horses. Due to its known interspecies transmission and the structure of the equine industry, the presence of this clone in horses poses a substantial health hazard for both animals and humans.

Regenerative Skin Wound Healing in Mammals: State-of-the-Art on Growth Factor and Stem Cell Based Treatments

Mammal skin has a crucial function in several life-preserving processes such as hydration, protection against chemicals and pathogens, initialization of vitamin D synthesis, excretion and heat regulation. Severe damage of the skin may therefore be life-threatening. Skin wound repair is a multiphased, yet well-orchestrated process including the interaction of various cell types, growth factors and cytokines aiming at closure of the skin and preferably resulting in tissue repair. Regardless various therapeutic modalities targeting at enhancing wound healing, the development of novel approaches for this pathology remains a clinical challenge. The time-consuming conservative wound management is mainly restricted to wound repair rather than restitution of the tissue integrity (the so-called “restitutio ad integrum”). Therefore, there is a continued search towards more efficacious wound therapies to reduce health care burden, provide patients with long-term relief and ultimately scarless wound healing. Recent in vivo and in vitro studies on the use of skin wound regenerative therapies provide encouraging results, but more protracted studies will have to determine whether the effect of observed effects are clinically significant and whether regeneration rather than repair can be achieved. For all the aforementioned reasons, this article reviews the emerging field of regenerative skin wound healing in mammals with particular emphasis on growth factor- and stem cell-based therapies.

Evaluation of excision, cryosurgery and local BCG vaccination for the treatment of equine sarcoids

Ninety-five horses with sarcoids were subjected to three types of treatment: surgical excision (conventional or carbon dioxide laser), cryotherapy or local BCG vaccination. The type of treatment was selected on the basis of the size, location and clinical appearance of the tumours. The choice between conventional and laser excision was empirical. A successful outcome was obtained in 1 1 of 14 (79 per cent) of the horses treated by cryosurgery, 18 of 27 (67 per cent) treated by BCG vaccination, 18 of 22 (82 per cent) treated by conventional excision, and 20 of 28 (71 per cent) treated with a carbon dioxide laser. For both excision methods, rigorous measures were taken to avoid autoinoculation and to ensure a wide margin of normal skin. The probability of local recurrence after excision was significantly higher for large sarcoids and sarcoids which had previously failed to respond to treatment. In 10 of the 31 horses with remaining sarcoids, some or all of the untreated sarcoids were observed to regress spontaneously.

Distal limb cast sores in horses: risk factors and early detection using thermography.

REASONS FOR PERFORMING STUDY There is a lack of evidence-based data on the prevalence, outcome and risk factors of distal limb cast sores, and no objective tool has been described for the early detection of cast sores. OBJECTIVES To investigate the prevalence, location, outcome and risk factors of cast sores after application of a distal limb cast and to determine whether static thermography of the cast is a valuable tool for the assessment of sores. METHODS A prospective study was conducted on horses treated with a distal limb cast. At each cast removal, cast sores were graded as superficial sores (SS), deep dermal sores (DS) or full thickness skin ulcerations (FS). In several cases, a thermographic evaluation of the cast was performed immediately prior to removal and differences in temperature (AT) between the coolest point of the cast and 2 cast regions predisposed for sore development (dorsoproximal mc/mtIII and palmar/plantar fetlock) were calculated. RESULTS Mean +/- s.d. total casting time of 70 horses was 31 +/- 18 days. Overall, 57 legs (81%) developed at least SS. Twenty-four legs (34%) ultimately developed DS and one horse had an FS. Multivariable analysis showed that the severity of sores was positively associated with increasing age (OR: 1.111, P = 0.028), a normal (vs. swollen) limb (OR: 3387, P = 0.023) and an increase in total casting time (OR per week: 1.363, P = 0.002). The thermographic evaluation (35 casts) revealed that the severity of sores was positively associated with increasing deltaT (OR: 2.100, P = 0.0005). The optimal cut-off values for the presence of SS and DS were set at, respectively, deltaT = 23 and 43 degrees C. CONCLUSION AND POTENTIAL RELEVANCE Distal limb cast is a safe coaptation technique with increasing risk of developing sores with time. Thermography is a valuable and rapid clinical tool to monitor the development of cast sores.

Bovine papillomavirus DNA can be detected in keratinocytes of equine sarcoid tumors

Bovine papillomavirus (BPV)-1 and -2 is linked to equine sarcoids, a commonly observed skin tumor in horses that is of considerable veterinary importance. Previous studies using in situ hybridization have detected BPV DNA only in fibroblasts and not in keratinocytes of sarcoids. In contrast, normal equine skin latently infected with BPV shows a dysplastic epithelium without dermal changes, similar to lesions induced by other papillomavirus types infecting the epithelium. The first goal of our study was to describe the epidermal and dermal characteristics of several stages in sarcoid development. Next, we explored whether BPV can infect epidermal cells in the horse using real-time PCR on laser-micro-dissected keratinocytes and fibroblasts. We found that latently infected normal skin samples and a subset of early stage sarcoids show dysplastic, koilocyte-like epithelial changes. BPV DNA was detected in keratinocytes in 40% of the samples with these particular epithelial properties, whereas advanced sarcoids only had BPV DNA in the fibroblasts. These data may indicate a novel and intriguing pathway of BPV infection in the horse composed of a first step of keratinocyte infection, followed by migration of viral material towards the dermis resulting in infection of sub-epidermal fibroblasts and their fully transformed phenotype. Additionally, an example of co-existence of a dermal BPV-1 and an epidermal BPV-2 infection in the same lesion is shown, indicating that horses can harbor infection with more than one BPV type at the same time.

OXA-23-producing Acinetobacter species from horses: a public health hazard?

Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; Department of Bacteriology and Immunology, CODA-CERVA-VAR, Groeselenberg 99, 1180 Brussels, Belgium; Department of Surgery and Anaesthesiology of Domestic Animals, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; Laboratory of Bacterial Genetics, National Institute of Public Health, Srobarova 48, 100 42 Prague, Czech Republic; Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine & Health Sciences, Ghent University, De Pintenlaan 185, Ghent, Belgium

Use of blood culture medium enrichment for synovial fluid culture in horses: a comparison of different culture methods.

REASONS FOR PERFORMING STUDY Standard methods for culturing equine synovial fluid (SF) are often unrewarding. Evidence-based information on the relative efficiency of different systems used for optimisation of isolation of microorganisms from equine SF is lacking. OBJECTIVES To compare the results of different culture systems performed in parallel on SF samples from horses clinically diagnosed with synovial sepsis. METHODS Synovial fluid specimens were collected between February 2007 and October 2008 from all horses admitted to a referral hospital that were clinically diagnosed with synovial sepsis and from control horses. Synovial fluid samples were cultured in parallel by: 1) direct agar culture (DA); agar culture after: 2) lysis-centrifugation pretreatment (LC); 3) conventional enrichment (CE); 4) combined LC/CE; or 5) blood culture medium enrichment using an automated system (BACTEC 9050). RESULTS Ninety SF samples from 82 horses were included, together with 40 control samples. Seventy-one of 90 samples (79%) were culture-positive by using blood culture medium enrichment (BACTEC), which was significantly higher compared to all other methods. BACTEC enrichment was never negative while any of the other methods was positive. Although agar culture following LC and/or CE resulted in a slightly higher number of positive samples compared to DA, this difference was not significant. All control samples were culture negative by the 5 different techniques. Although the majority of samples containing isolates recovered without enrichment, culture results after BACTEC enrichment were available on the same day as for agar culture with or without LC (19/23 samples), while CE postponed recovery by at least one day in 20/23 samples. CONCLUSION Blood culture medium enrichment is superior to other techniques for isolation of bacteria from SF of horses. The use of an automated system allows enrichment without substantially postponing recovery of microorganisms. POTENTIAL RELEVANCE The efficient and fast isolation of microorganisms from infected SF by the BACTEC system allows for rapid susceptibility testing and a more appropriate antibiotic treatment.

EcPV2 DNA in equine genital squamous cell carcinomas and normal genital mucosa

Squamous cell carcinoma (SCC) represents the most common genital malignant tumor in horses. Similar to humans, papillomaviruses (PVs) have been proposed as etiological agents and recently Equine papillomavirus type 2 (EcPV2) has been identified in a subset of genital SCCs. The goals of this study were (1) to determine the prevalence of EcPV2 DNA in tissue samples from equine genital SCCs, penile intraepithelial neoplasia (PIN) and penile papillomas, using EcPV2-specific PCR, (2) to examine the prevalence of latent EcPV2 infection in healthy genital mucosa and (3) to determine genetic variability within EcPV2 and to disentangle phylogenetic relationships of EcPV2 among PVs. EcPV2 DNA was detected in all but one penile SCC (15/16), in all PIN lesions (8/8) and penile papillomas (4/4). Additionally, EcPV2 DNA was demonstrated in one of two metastasized lymph nodes, one contact metastasis in the mouth, two vaginal and one anal lesion. In healthy horses, EcPV2 DNA was detected in 10% (4/39) of penile swabs but in none of vulvovaginal swabs (0/20). This study confirms the presence of EcPV2 DNA in equine genital SCCs and shows its involvement in anal lesions, a lymph node and contact metastases. Latent EcPV2 presence was also shown in normal male genital mucosa. We found that different EcPV2 variants cocirculate among horses and that EcPV2 is related to the Delta+Zeta PVs and is only a very distant relative of high-risk human PVs causing genital cancer. Thus, similar viral tropism and similar malignant outcome of the infection do not imply close evolutionary relationship.

Methicillin-resistant Staphylococcus aureus (MRSA) on the skin of long-term hospitalised horses

Given the significance of methicillin-resistant Staphylococcus aureus (MRSA) infections for both horses and staff in equine veterinary hospitals, protocols are required to minimise the risk of nosocomial transmission, including the screening of the skin and nasal chambers of equine patients for evidence of infection. The objective of this study was to clarify the potential existence and extent of MRSA on the skin of horses requiring long-term hospitalisation (≥ 6 months). Thirty such horses were sampled at eight different locations on their skin and from their nasal chambers. MRSA was isolated from 12 animals (40%), with all sample sites testing positive on at least one occasion. Organisms were most frequently detected in the nasal chambers (relative sensitivity, 83.3%; 34.5% positive horses; isolation rate 33.3%). Skin presence was found in 30% of animals with the highest isolation rates found at the carpus (16.7%), neck, withers and croup (13.3% each). To achieve a relative screening sensitivity of >90%, at least one skin site was required in addition to nasal sampling. This evidence of skin as well as nasal reservoirs of MRSA in long-term hospitalised horses should facilitate the design of effective screening and containment protocols.

Partial tibial neurectomy in 113 Belgian blue calves with spastic paresis

One hundred and thirteen double-muscled Belgian blue calves (69 males and 44 females) with spastic paresis (52 unilateral and 61 bilateral) were treated surgically by partial tibial neurectomy under caudal epidural anaesthesia. Telephone inquiries made at least three-and-a-half months later established that good results were obtained in 83.2 per cent of the calves; a considerable improvement was reported in 4.4 per cent which still had intermittent spastic contractions; severe hyperflexion of the hock necessitating early slaughtering was recorded in 4.4 per cent of the calves; and in 8 per cent there was little or no improvement.