Staphylococcus is a genus of bacteria commonly found on the skin and mucous membranes of horses. These bacteria can be part of the normal flora but may also act as opportunistic pathogens, leading to infections under certain conditions. In horses, Staphylococcus species can cause a range of infections, including skin infections, wound infections, and more severe conditions such as septicemia. The most frequently identified species in equine infections is Staphylococcus aureus, known for its ability to resist certain antibiotics, complicating treatment efforts. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, pathogenic mechanisms, and treatment strategies of Staphylococcus infections in horses.
Devriese LA, Nzuambe D, Godard C.One hundred and twenty eight strains of Staphylococcus from lesions, mostly of the skin, in horses were identified and compared with 29 strains isolated from the healthy skin. The pathogenic species Staphylococcus aureus, S. intermedius and S. hyicus were found almost exclusively in lesions. Other species such as S. xylosus and S. sciuri were more frequently found on the healthy skin than in lesions. The S. aureus strains formed a very heterogeneous collection. Many of these strains were staphylokinase positive and rapidly coagulated bovine plasma. Such strains are rarely found in other animal...
Bertram TA, Jensen AE.Morphology and function of equine neutrophils were evaluated after combination with contagious equine metritis organism (CEMO) or 1 of 2 CEMO lipopolysaccharides (LPS). The 2 LPS (LPS-a; LPS-p) isolated from the CEMO contained 14- and 16-carbon fatty acids, ketodeoxyoctanate, hexose, and heptose, but were morphologically distinct. Neutrophils exposed to LPS had fewer granules, whereas those exposed to CEMO had more granules than did the controls (phosphate-buffered saline solution). Neutrophil iodination was significantly increased with 10 and 25 micrograms of LPS-a, but not significantly alte...
Coignoul FL, Bertram TA, Roth JA, Cheville NF.Neutrophils from 4 pony foals, 3 lactating pony mares, and 3 nonlactating mares were evaluated ultrastructurally and by in vitro function tests. Neutrophils from foals had significantly (P = 0.05) less random migration than neutrophils from mares; values in tests for iodination and Staphylococcus aureus ingestion were also lower with foal neutrophils. Neutrophils from lactating mares had lower responses to iodination, antibody-dependent cell-mediated cytotoxicity, and random migration tests than did neutrophils from nonlactating mares. Ultrastructurally, granule concentration did not differ si...
Biberstein EL, Jang SS, Hirsh DC.A total of 268 isolates of coagulase-positive staphylococci from a variety of animal species, including dogs, horses, cats, monkeys, goats, and cows, were assigned to species on the basis of the API Staph- Ident system (Analytab Products, Inc., Plainview , N.Y.). Of 195 isolates from dogs, 179 (91.8%) were Staphylococcus intermedius, as were 9 of 25 (36%) isolates from horses, 7 of 15 (46.6%) isolates from cats, and 4 of 6 (66.6%) isolates from goats. Only 1 of 10 isolates from monkeys and none of 7 isolates from cows were S. intermedius. Of the remaining 68 cultures, 63 were identified as Sta...
Lynch JA.A Staphylococcus aureus infection in a mature horse, resulting from trauma, is described, which proved refractory to antibiotic therapy directed by the results of antibiotic sensitivity testing. After a prolonged course, rapid resolution of the infection was achieved with the administration of an autogenous formalized bacterin.
Devriese LA, Vlaminck K, Nuytten J, De Keersmaecker P.Staphylococcus hyicus (subspecies hyicus) was isolated as the only pathogenic organism from two independent cases of dermatitis of the lower parts of the limbs (grease heel) in horses. The organism was recovered together with other pathogenic staphylococci from similar conditions in two other horses of different origins. These conditions were characterised by epidermolysis, alopecia and crust formation. They responded quickly to antibiotic treatment. The organism was also isolated from a long standing case of "summer eczema" which healed without antibiotic treatment, and from a horse with derm...
McLaughlin SA, Brightman AH, Helper LC, Manning JP, Tomes JE.In 123 cases of external ocular disease in the horse, pathogenic microorganisms isolated with greatest frequency were Streptococcus sp (43.9%), Staphylococcus sp (24.2%), and Pseudomonas sp (13.8%). Fungi were isolated in 4.8% of the cases. In vitro testing showed that most of the Streptococcus sp isolants were sensitive to ampicillin, cephalothin, and carbenicillin. Most of the Staphylococcus sp isolants were sensitive to gentamicin, cephalothin, and bacitracin. Most of the Pseudomonas sp isolants were sensitive to polymyxin B and gentamicin.
Barber SM.A three year old Thoroughbred filly was examined because of bilateral nasal discharge and external swelling of the left laryngeal area. Endoscopy revealed an enlarged left arytenoid cartilage, left laryngeal hemiplegia and drainage of purulent material into the lumen of the larynx. Radiographs showed a large fluid and gas filled cavity overlying the caudal larynx and cranial trachea. Surgical drainage and debridement of the abscess led to complete healing by secondary intention. Laryngeal ventriculectomy was performed as a treatment for left laryngeal hemiplegia, but a grave prognosis for resp...
Love DN, Rose RJ, Martin IC, Bailey M.Amoxycillin trihydrate was administered orally to 6 foals at dose rates of 13 mg/kg (low), 20 mg/kg (medium) and 30 mg/kg (high) and serum concentrations determined at intervals up to 8 h. Therapeutic serum levels of 1 microgram/ml persisted for 268 mins at a dose rate of 13 mg/kg, for 339 mins at 20 mg/kg and for 381 mins at 30 mg/kg. A 2 micrograms/ml serum level persisted for 198 mins at a dose rate of 13 mg/kg, for 268 mins at 20 mg/kg and for 311 mins at 30 mg/kg. To determine the spectra of its antibacterial activity, the minimum inhibitory concentrations of amoxycillin against 8 genera ...
Turner WH, Pickard DJ.A new haemolysin from Staphylococcus aureus produced opaque zones of haemolysis on horse blood agar but did not lyse equine erythrocytes suspended in phosphate-buffered saline. The haemolysin was not neutralized by normal rabbit serum and was distinct from alpha-, beta- and delta-haemolysins as well as human leucocidin. Partially purified preparations produced erythema when injected intradermally into rabbit skin.
Jahrling PB, Hesse RA, Metzger JF.A radioimmunoassay (RIA) procedure is described for measuring antibodies to alphaviruses in human and other mammalian sera. The test employed protein Abearing Staphylococcus aureus as a solid-phase immunoadsorbent for (3)H-labeled viruses complexed with immunoglobulin G. Using antibodies produced in humans and guinea pigs, the RIA procedure clearly differentiated among antibodies to Venezuelan, western, and eastern equine encephalomyelitis viruses. Sensitivity of the RIA depended on the concentrations of labeled viruses employed. The dilution of serum that effected binding of 50% of the (3)H-l...
Cattabiani F, Cabassi E, Allodi C, Gianelli F.The AA. report the results of taxonomic research conducted on the conjunctival sac of 59 horses for identification of the present bacterial flora. In the controlled animals, it was observed, at the level of the considered niche, a community constituted of normal bacterial populations, but not autochtonous in the significance they attributed from DUBOS et al., relative to the characterization of the indigenous microbiota of the intestine. The isolated normal bacterial flora seems to be constituted of: Micrococcus (subgroup 6 of Baird-Parker, M. luteus, Micrococcus spp.) isolated in 49,15% of th...
Oeding P, Hájek V, Marsálek E.Out of 70 S. aurew strains isolated from the anterior nares of horses, 48 (69 per cent)
belonged to the E biotype. Approximately one third of these isolates were typed with factor
sera, the 6 (35 per cent) that were typable showing 5 different patterns. All strains but one
were non-typable with the basic sets of phages for typing human and bovine staphylococci
even at RTD x 100. Without any exception the equine staphylococci of the E biotype
contained polysaccharide Aa. Sixteen biochemically different strains belonged to the biotype A, B or C. A number of different serological patterns an...
Haque RU.A technique for identifying and characterizing staphylococcal hemolysins by first separating them electrophoretically in barbital-buffered agar gel (pH 8.4) at 5 ma/cm for 2 hr and then determining their hemolytic activities by exposing them to human, horse, rabbit, and sheep erythrocytes is described. The alpha-hemolysin produced by a White variant of the Wood 46 strain of Staphylococcus aureus migrated 18 mm towards the cathode, and it lysed horse, rabbit, and sheep erythrocytes, whereas a Clear variant of the Wood 46 strain of S. aureus produced a lysin which migrated similarly to the alpha...
To investigate predictors of survival and athletic function in adult horses with infection of a synovial structure. Objective: Increasing duration from contamination to referral, bone or tendon involvement and positive microbial culture decreases short-term survival. Synovitis and/or sepsis at 5 days post-admission and involvement of Staphylococcus spp. decreases long-term athletic function. Methods: Retrospective study. Methods: Records over 4 years of adult horses with synovial sepsis were reviewed. A two-tailed Fisher's exact test, Mann-Whitney U test or t-test was used to examine whether v...
A 3-year-old Thoroughbred gelding was examined because of clinical signs of pneumonia and shock. Mucous membrane petechiation and ventral edema were observed and considered to be a result of vasculitis. Epidermal necrosis developed on the distal portions of the limbs. The horse had a persistent high fever that was unresponsive to nonsteroidal anti-inflammatory treatment, and Staphylococcus aureus was isolated from a nasal swab specimen and 2 transtracheal wash fluid samples. Antimicrobial, anti-inflammatory, and supportive treatment resulted in clinical improvement. However, resolution of the ...
Methicillin-resistant Staphylococcus aureus (MRSA) is an emerging problem in horses; however, the epidemiology of infection and colonization is poorly understood. This study evaluated factors associated with MRSA colonization at the time of admission to a veterinary teaching hospital. A case-control study evaluating historical factors was performed. Previous colonization of the horse, previous identification of colonized horses on the farm, antimicrobial administration within 30 days, admission to the neonatal intensive care unit, and admission to a service other than the surgical service were...
Bosch G, van Duijkeren E, Bergwerff AA, Rijkenhuizen AB, Ensink JM.Ceftiofur concentrations in an infected and uninfected environment were compared and the efficacy of locally administered ceftiofur was evaluated in an experimental infection with Staphylococcus aureus in tissue cages. Eight ponies had tissue cages (TCs) implanted s.c. on each side of the neck. Into one of the cages 150 mg of ceftiofur was administered and fluid samples were taken to determine ceftiofur concentrations. After 1 week the other TC was infected with S. aureus and subsequently treated with 150 mg ceftiofur administered locally into the TC once daily for 21 days. Samples of fluid we...
Kuroda T, Minamijima Y, Niwa H, Mita H, Tamura N, Fukuda K, Kuwano A, Sato F.Cephalothin (CET) concentrations in body fluids (plasma, synovial fluid, pleural fluid, peritoneal fluid, and aqueous humor) and tissue samples (bone, lung, jejunum, hoof, and subcutaneous tissue) were investigated to consider the treatment of infectious diseases in horses. CET 22 mg/kg body weight was intravenously administered to 12 horses. Samples were collected from four different horses at 1, 3, and 5 hr after administration. The CET concentration in body fluids other than aqueous humor was maintained above the MIC90 values of Streptococcus zooepidemicus and Staphylococcus aureus until 5 ...
Crisman MV, Hodgson DR, Bayly WM, Liggitt HD.To determine whether road transport affected pulmonary phagocyte activity, 7 healthy Thoroughbred horses were shipped 1,160 kilometers over 36 hours. Fluid collected by bronchoalveolar lavage (BAL) 12 hours, and 7 and 14 days after transport was analyzed. Results were compared to those from the same horses pre-transport, and 7 non-transported control horses that had BAL performed at the same times as the transported horses. Of cells recovered with BAL the percentage of viable pulmonary alveolar macrophages (PAMs) declined from 90.0 +/- 0.9% pre-transport to 80.0 +/- 3.7% by 2 weeks post transp...
De Clercq E, Den Hondt S, De Baere C, Martens AM.To compare the effect of multiple wound dressings on microbial growth in a perfused equine wound model. Methods: Abdominal musculocutaneous flaps from 16 equine cadavers. Methods: 8 full-thickness skin wound covered were created in each flap. Tissues were perfused with saline (0.9% NaCl) solution. Wounds were inoculated with methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa (106 CFUs), incubated, and covered with a dressing containing activated charcoal, boric acid, cadexomer iodine, calcium alginate, manuka honey, nanoparticle silver, or polyhexamethylene biguanide ...
Ryu SH, Koo HC, Lee YW, Park YH, Lee CW.Infectious upper respiratory disease (IURD) of Thoroughbred racehorses has been a frequent problem (29.6% of incidence) at the Seoul Race Park (Korea). Risk factors for IURD include the season with a high transfer rate (summer and fall), the stabling period (≤ 3 months), and age (2 to 3 years old), suggesting that the movement and new environment may have depressed the immune system of the horses and decreased their ability to respond properly to pathogens. The bacterial strains (n = 98) isolated from IURD horses included Pseudomonas spp., Escherichia coli, Staphylococcus spp., Streptococcus...
Hüthwohl H, Weiss R, Schmeer N, Schliesser T.Classification based on biochemical characteristics of 389 strains of plasma-coagulase-negative (plc-) staphylococci isolated from the genital tract of mares and stallions resulted in the following distribution of species: St. sciuri 130 (33.4%), St. equorum 42 (10.8%), St. xylosus 16 (4.1%), St. epidermidis 35 (9.0%), St. simulans 24 (6.2%), St. haemolyticus 33 (8.5%), St. warneri 18 (4.6%), St. lentus 12 (3.1%), St. hyicus 11 (2.8%). Strains of St. cohnii, St. capitis, St. gallinarum, St. saprophyticus and St. hominis have only been found sporadically (a. 1%). 48 (12.3%) strains could not be...
Thompson NE, Bergdoll MS, Pattee PA.The factor in normal sera primarily responsible for the enhancement of transfection (and transformation) of Staphylococcus aureus was identified as fibronectin. Serum samples which were depleted of fibronectin by affinity chromatography showed a marked decrease in enhancing activity. Fibronectin isolated from sera of several animal species demonstrated enhancing activity.
Espíndola JP, Machado G, Diehl GN, Dos Santos LC, de Vargas AC, Gressler LT.Microbiological diagnosis of equine respiratory infections is essential for disease management. However, reliable diagnosis can be a challenge due to colonization of the upper respiratory tract (URT) by a diverse microbial population, and because there is a lack of studies with samples from healthy animals. Aiming to guide adequate URT culture, this work reports culturable microbial population from the URT of 1,010 apparently healthy horses from 341 farms in Southern Brazil and identifies the putative presence of pathogenic microorganisms. Nasal swabs were cultured in 5% blood agar, and the is...
Satorov SS, Orzuev MI.Staphylococci occur in donkeys more frequently than in other animals, and only from donkeys coagulase-negative staphylococci, characteristic of humans (S. hominis, S. capitis, S. cohnii), were isolated. Least frequently staphylococcal carrier state was registered in cats; in these animals only coagulase-negative strains were found to occur. From 30 donkeys coagulase-positive staphylococci belonging to 47 S. aureus strains were isolated. These strains differed from known ecological variants in their biological properties, thus suggesting the existence of S. aureus ecovar specific for donkeys. T...
Kannekens-Jager MM, Duim B, der Graaf-van Bloois LV, Zomer AL, Broekhuizen-Stins MJ, Boswinkel M, Wagenaar JA, Broens EM.In 2020 and 2022, nine cases of surgical site infections with a methicillin-resistant Staphylococcus aureus (MRSA) were diagnosed in horses in an equine referral clinic. Sixteen isolates (horses, n=9; environment, n=3; and staff members, n=4) were analysed retrospectively using Nanopore whole-genome sequencing to investigate the relatedness of two suspected MRSA outbreaks (2020 and 2022). The MRSA isolates belonged to ST398 and ST612. ST398 genomes from 2020 and 2022 formed three phylogenetic clusters. The first ST398 cluster from 2020 consisted of isolates from five horses and one staff membe...
Papouskova A, Drabkova Z, Brajerova M, Krutova M, Cizek A, Tkadlec J.We performed a retrospective analysis of MRSA isolates collected at the university equine clinic including clinical isolates from 2008 to 2021 and screening environmental, equine and personnel isolates from 2016. Screening and clinical samples were cultured on Brilliance MRSA 2 and Columbia agar (Oxoid), respectively, with enrichment for environmental samples. Antimicrobial susceptibility was assessed by disc diffusion. All the isolates were characterized by spa typing. Eighteen selected isolates were subjected to WGS with subsequent wgMLST clonal analysis. Among 75 MRSA isolates, five spa typ...
Khatibzadeh SM, Dahlgren LA, Caswell CC, Ducker WA, Werre SR, Bogers SH.Biofilms reduce antibiotic efficacy and lead to complications and mortality in human and equine patients with orthopedic infections. Equine bone marrow-derived mesenchymal stromal cells (MSC) kill planktonic bacteria and prevent biofilm formation, but their ability to disrupt established orthopedic biofilms is unknown. Our objective was to evaluate the ability of MSC to reduce established S. aureus or E. coli biofilms in vitro. We hypothesized that MSC would reduce biofilm matrix and colony-forming units (CFU) compared to no treatment and that MSC combined with the antibiotic, amikacin sulfate...
Haenni M, Murri S, Drapeau A, Rafidinarivo I, Gilles S, Keck N, Léon A, Sulter A, Tricaud MC, François P, Madec JY.Staphylococcus aureus is an important zoonotic pathogen that has often been seen in animals through the prism of the MRSA clonal complex (CC) 398 in pigs and in-contact humans. The goal of this study was first to assess the prevalence of MRSA, and second to look for MSSA CC398 in cats, dogs and horses in France. Methods: Clinical S. aureus isolates (n = 479) were collected from 186 cats, 143 dogs and 150 horses during 2022-2023 all over the French territory. Antibiograms were performed on all isolates. MRSA and MSSA CC398 isolates were subject to WGS. Core genome (cg) MLST-based and SNP-ba...
Styková E, Valocký I, Kačírová J, Fecskeová LK.Equine pastern dermatitis (EPD) is a multifactorial disease with a change in the skin microbiome. The present study monitored the influence of Weissella cibaria Biocenol™ 4/8 D37 CCM 9015 stabilized on alginite on the skin microbiota of healthy horses and model patients with EPD. Based on clinical signs, EPD lesions were identified as exudative or proliferative forms. A comparison of the initial microbial community based on 16S rRNA amplicon sequencing revealed that there was a statistically significant difference between healthy vs. exudative (R = 0.52, p = 0.003) and exudative vs. ...
Marsella R.Information on skin barrier in horses is limited. A study on the epidermal ultrastructure of normal and allergic horses documented disorganized amorphous intercellular lipids in the stratum corneum of allergic samples. These findings are similar to atopic canine and human skin. Currently, there is no published study comparing skin barrier function parameters between normal and allergic horses; thus, the functional implications of the ultrastructural changes are unknown. In normal horses, body location, gender, breed, and ambient conditions affect skin barrier parameters, such as Transepidermal...
Lin H, Deng D, Yan Z, Zou G, Shen Y.Staphylococcus aureus can transfer from animals to humans. Lichuan horse is an isolated breed living in a high-altitude area with limited use of antibiotics and is bred for use in tourism. To evaluate the risk of human-animal cross-transmission, the S. aureus was isolated from three horse farms in Lichuan, including healthy horses and horses with skin infections, farm workers and environment. From a collection of 111 samples, 18 S. aureus isolates were obtained. All the isolates were genome sequenced and their biological characteristics including antimicrobial susceptibility, virulence and bi...
Clarysse M, Bertier P, Verpaele S, Madsen AM, Vlaminck L.Equine dental disorders, such as sharp enamel points and focal overgrowths, are common in horses and are often treated with motorized dental grinding tools. These tools, while effective, produce dust and aerosols that may pose health risks to veterinarians and nearby individuals. This study aimed to assess the health risks associated with dental dust and aerosols generated during equine odontoplasty. Using a realistic setup, air concentrations of inhalable and respirable dust, crystalline silica, and airborne microorganisms and endotoxins were measured in 12 groups of horses undergoing odontop...
Guillot M, Mespoulhes-Rivière C, Bousquet-Mélou A, Lacroix MZ, Roques BB, Lallemand EA.Intravenous regional limb perfusion (IVRLP) of antibiotics is a therapeutic method used to treat distal limb infections in horses. The objectives of this study were to determine the pharmacokinetic parameters and tolerance of sodium benzylpenicillin (NaBP) administered via IVRLP; to compare the feasibility, tolerance, and efficacy of performing IVRLP on a flexed limb versus a weightbearing limb; and to predict the efficacy of IVRLP using gentamicin or NaBP. A prospective crossover study was conducted with six horses, each undergoing four phases of antibiotic infusion (gentamicin at 2.2 mg/kg ...
Strompfová V, Štempelová L, Bujňáková D, Karahutová L, Gondoľová D, Nagyová M, Siegfried L.In order to develop non-antibiotic therapies to treat dermatological diseases it is urgent to spread knowledge on composition and properties of skin bacteria in healthy animals. Since horses are popular companions of humans, it is necessary to know what risk skin bacteria pose to humans. Therefore the aim of this work was to analyse species composition of staphylococci isolated from skin swabs of 50 healthy horses using MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization Time-of-Flight) spectrometry and to characterize their virulence properties. Swabs were collected from five body areas (n...
Stolle LM, Oltmanns H, Meißner J, Heun F, Schieder AK, Wolff HT, Ohnesorge B, Busse C.To determine the in vitro antimicrobial activity of specific antiseptics against common equine ocular surface pathogens. Methods: Staphylococcus aureus (S. aureus) (n = 12), Streptococcus equi subspecies zooepidemicus (S. zooepidemicus) (n = 9), Enterobacter hormaechei (E. hormaechei) (n = 6), and Bacillus cereus (B. cereus) (n = 5) were collected from corneal samples of horses with ulcerative keratitis. Reference strains were included. Minimum bactericidal concentrations (MBC) of polyhexanide, povidone-iodine, and hypochlorous acid were tested using the microdilution method. ...
Barvelink M, Brok B, Djajadiningrat-Laanen SC, Vernooij JCM, Broens EM, Slenter IJM.To assess the antibacterial activity of manuka honey against bacterial isolates commonly associated with infected corneal ulcerations in horses, and to investigate possible combined effects of manuka honey and commonly prescribed topical antibiotics. Methods: Four Staphylococcus aureus, including three methicillin-resistant (MRSA), two methicillin-resistant coagulase-negative staphylococci (S. sciuri and S. haemolyticus), and two Streptococcus equi subspecies zooepidemicus isolates from horses with stromal ulcerative keratitis were selected. Minimum inhibitory concentrations (MICs) and minimu...
: isolates from humans and horses of the equine-associated clonal complexes (CCs) CC1 and CC1660 were comparatively investigated for their genomic relationships. : A total of 91 isolates (64 human, 27 equine) were subjected to whole-genome sequencing (WGS), sequence analysis, and antimicrobial susceptibility testing. : WGS confirmed 75 CC1 and 16 CC1660 isolates, comprising nine sequence types (STs) in CC1 and four STs in CC1660. Ten types were present in CC1 and five in CC1660. In the gene of three CC1 isolates, a 285 bp deletion was detected, and a nucleotide deletion causing a premature...
Christofi E, Hoopes J, El-Hage C, Coffin J, Riley T, Cumming B.Since their arrival in the 1700s, horses have played a significant role in shaping the identity of rural and remote communities. However, Indigenous perspectives on the historical role of horses in communities have been largely underrepresented. In remote regions, where access to veterinary and medical services is limited, interactions between people and free-roaming horses present a potential risk for zoonotic disease transmission. This review identifies potential pathways for the transmission of equine zoonoses in rural and remote Aboriginal and Torres Strait Islander communities, aiming to ...
