Pathogens are microorganisms, such as bacteria, viruses, fungi, and parasites, that can cause disease in horses. These microorganisms interact with the equine immune system, often leading to a range of health issues that can affect individual horses or entire populations. Pathogens can be transmitted through various routes, including direct contact, vectors, or environmental exposure. Common equine pathogens include Streptococcus equi, Equine Herpesvirus, and Strongylus vulgaris. Understanding the interactions between equine hosts and pathogens is essential for disease prevention, management, and treatment. This page compiles peer-reviewed research studies and scholarly articles that explore the identification, transmission, and impact of pathogens on equine health.
Hammerschmitt ME, Rolim VM, Snel GGM, Siqueira FM, Driemeier D, Pavarini SP.Chromobacterium violaceum is an opportunistic pathogen of mammals that produces characteristic violet pigment in bacterial culture. We report pneumonia and septicaemia caused by C. violaceum in a horse. Necropsy examination was performed on a 3-year-old Quarter Horse stallion with a history of recurrent episodes of pneumonia, fever, dyspnoea and sanguineous nasal discharge. The lungs were not collapsed, but they contained dark red foci mixed with white areas, and multiple nodules of firm consistency. Within the liver and kidney there were randomly distributed, multifocal, white pinpoint lesion...
Stewart AS, Pratt-Phillips S, Gonzalez LM.All species, including horses, suffer from alterations that increase intestinal permeability. These alterations, also known as "leaky gut," may lead to severe disease as the normal intestinal barrier becomes compromised and can no longer protect against harmful luminal contents including microbial toxins and pathogens. Leaky gut results from a variety of conditions including physical stressors, decreased blood flow to the intestine, inflammatory disease, and pathogenic infections, among others. Several testing methods exist to diagnose these alterations in both a clinical and research setting....
Kelmer G, Tatz AJ, Kdoshim E, Britzi M, Segev G.This prospective experimental study goal was to determine the pharmacokinetics of imipenem after intravenous regional limb perfusion (IV-RLP) in standing horses. Nine horses participated in the study; that was approved by the University Animal Care and Use Committee. One thoracic limb or one pelvic limb of each horse was randomly selected. After the veins were catheterized, an Esmarch bandage tourniquet was applied and the catheter was injected with a solution containing 500mg of imipenem. Synovial fluid samples were collected from the fetlock joint and blood samples were collected from the ju...
Nielsen MK, Lyons ET.Cyathostomins (small strongyles) are ubiquitous in grazing horses and are known pathogens as cause of larval cyathostominosis. As part of their life cycle, cyathostomin larvae invade the mucosal walls of the large intestines and undergo encystment. Newly ingested third stage larvae are known to undergo arrested development and this can lead to an accumulation of encysted burdens over the course of a grazing season. It is believed that the host immune system plays a significant role in triggering this arrestment. Little is known about the development and progression of larval stages in foals th...
Baraúna RA, Ramos RTJ, Veras AAO, de Sá PHCG, Guimarães LC, das Graças DA, Carneiro AR, Edman JM, Spier SJ, Azevedo V, Silva A.The genomes of four strains (MB11, MB14, MB30, and MB66) of the species Corynebacterium pseudotuberculosis biovar equi were sequenced on the Ion Torrent PGM platform, completely assembled, and their gene content and structure were analyzed. The strains were isolated from horses with distinct signs of infection, including ulcerative lymphangitis, external abscesses on the chest, or internal abscesses on the liver, kidneys, and lungs. The average size of the genomes was 2.3 Mbp, with 2169 (Strain MB11) to 2235 (Strain MB14) predicted coding sequences (CDSs). An optical map of the MB11 strain gen...
Witkowski L, Rzewuska M, Takai S, Chrobak-Chmiel D, Kizerwetter-Świda M, Feret M, Gawryś M, Witkowski M, Kita J.Rhodococcus equi is one of the most significant bacterial pathogens affecting foals up to 6 months of age worldwide. Rhodococcosis is present in Poland however information about molecular characterization of R. equi isolates is scarce. This study describes molecular characterization of Rhodococcus equi infection on 13 horse breeding farms in Poland between 2001 and 2012. Samples were collected by tracheobronchial aspiration from pneumonic foals or during necropsy. The R. equi isolates were genotyped by plasmid profiling and pulsed-field gel electrophoresis. Results: Totally, 58 R. equi isolat...
Azarvandi A, Khosravi AR, Shokri H, Talebkhan Garoussi M, Gharahgouzlou F, Vahedi G, Sharifzadeh A.Yeasts are commensal organisms found in the reproductive and gastrointestinal tracts, and on the skin and other mucosa in mammals. Objective: The purpose of this study was to isolate and identify yeast flora in the caudal reproductive tract in healthy female horses. Methods: Longitudinal study. Methods: A total of 453 samples were collected using double-guarded swabs from the vestibule, clitoral fossa and vagina in 151 horses. All samples were cultured on Sabouraud 4% dextrose agar and incubated at 35°C for 7-10 days. Isolates were identified according to their morphological characteristics a...
Javed R, Taku AK, Sharma RK, Badroo GA.The aim was to determine the occurrence of in equines and their environment in Jammu (R.S. Pura, Katra), molecular characterization and to determine the antibiotic resistance pattern of . Methods: A total of 96 nasopharyngeal swab samples were collected from equines. The organism was isolated on Columbia nalidixic acid agar containing 5% sheep blood as well as on sheep blood agar and was later confirmed by cultural characteristics and biochemical tests. Molecular detection of isolates was done by gene amplification followed by virulence associated protein A () gene amplification. Antibiogra...
Hunyadi L, Sundman EA, Kass PH, Williams DC, Aleman M.Immune-mediated myositis (IMM) is a cause of rhabdomyolysis, stiffness, and muscle atrophy predominantly affecting Quarter horses. Limited information is available with regard to outcome, prognostic indicators, and associations with concurrent diseases. Objective: To report outcomes and associations between outcome and clinical and laboratory parameters, and presence of concurrent illness. Methods: Sixty-eight horses; 52 Quarter horses and related breeds and 16 other breeds. Methods: Retrospective cohort study (1991-2014). Medical records of horses with histological diagnosis of IMM were revie...
Edwards SH, Khalfan SA, Jacobson GA, Pirie AD, Raidal SL.OBJECTIVE To determine plasma drug concentrations after IV administration of a bolus followed by continuous rate infusion (CRI) of sodium benzylpenicillin and ceftiofur sodium to healthy adult horses. ANIMALS 6 Thoroughbred mares (3 to 9 years old; mean ± SD body weight, 544 ± 55 kg) with no history of recent antimicrobial treatment. PROCEDURES Horses were used in 2 experiments conducted 14 days apart. For each experiment, horses were housed individually in stables, and catheters were placed bilaterally in both jugular veins for drug administration by CRI (left catheter) and for intermittent...
Olivo G, Lucas TM, Borges AS, Silva RO, Lobato FC, Siqueira AK, da Silva Leite D, Brandão PE, Gregori F, de Oliveira-Filho JP, Takai S, Ribeiro MG.Diarrhea is a major clinical problem affecting foals up to 3 months of age. The aim of this study was to identify enteric microorganisms involved in monoinfections and coinfections and the associated virulence factors in healthy and diarrheic foals. Diarrheic (D) ( = 56) and nondiarrheic (ND) foals ( = 60) up to three months of age were studied. Fecal samples were analyzed for identification of infectious agents (microbiological culturing, molecular techniques, and microscopic analyses). (30% versus 25%), spp. (25% versus 7%), (25% versus 25%), type A (21% versus 10%), (20% versus 35%), ...
Haas DJ, Dorneles EM, Spier SJ, Carroll SP, Edman J, Azevedo VA, Heinemann MB, Lage AP.Corynebacterium pseudotuberculosis biovar Equi is an important pathogen of horses. It is increasing in frequency in the United States, and is responsible for various clinical forms of infection, including external abscesses, internal abscesses of the abdominal or thoracic cavities, and ulcerative lymphangitis. The host/pathogen factors dictating the form or severity of infection are currently unknown. Our recent investigations have shown that genotyping C. pseudotuberculosis isolates using enterobacterial repetitive intergenic consensus (ERIC)-PCR is useful for understanding the evolutionary g...
Elschner MC, Thomas P, Melzer F.Burkholderia mallei is a zoonotic agent causing glanders, a notifiable disease in equines. During the past decades glanders emerged, and the Kingdom of Bahrain reported outbreaks to the World Organization of Animal Health in 2010 and 2011. This paper presents the complete genome sequence of the Burkholderia mallei strain 11RR2811 Bahrain1.
Goodman LB, Anderson RR, Slater M, Ortenberg E, Renshaw RW, Chilson BD, Laverack MA, Beeby JS, Dubovi EJ, Glaser AL.Nanoliter scale real-time PCR uses spatial multiplexing to allow multiple assays to be run in parallel on a single plate without the typical drawbacks of combining reactions together. We designed and evaluated a panel based on this principle to rapidly identify the presence of common disease agents in dogs and horses with acute respiratory illness. This manuscript describes a nanoscale diagnostic PCR workflow for sample preparation, amplification, and analysis of target pathogen sequences, focusing on procedures that are different from microliter scale reactions. In the respiratory panel prese...
Yarnell K, Le Bon M, Turton N, Savova M, McGlennon A, Forsythe S.To compare the rate of growth of four microbial strains that cause disease in the horse, on four commonly used types of bedding. The moisture-holding capacity of each bedding type was also tested. Results: Microbial strains included Streptococcus equi, Streptococcus zooepidemicus, Fusobacterium necrophorum, Dichelobacter nodosus and Dermatophilus congolensis. The bedding types tested were Pinus sylvestris (Scots pine shavings), Pinus nigra (Corsican pine shavings), Picea sitchensis (Sitka spruce shavings), Cannabis sativa (hemp) and chopped wheat straw. A suspension of each microbial strain wa...
Dugat T, Zanella G, Véran L, Lesage C, Girault G, Durand B, Lagrée AC, Boulouis HJ, Haddad N.Anaplasma phagocytophilum is the causative agent of tick-borne fever, a disease with high economic impact for domestic ruminants in Europe. Epidemiological cycles of this species are complex, and involve different ecotypes circulating in various host species. To date, these epidemiological cycles are poorly understood, especially in Europe, as European reservoir hosts (i.e. vertebrate hosts enabling long-term maintenance of the bacterium in the ecosystem), of the bacterium have not yet been clearly identified. In this study, our objective was to explore the presence, the prevalence, and the ge...
Adamska M, Skotarczak B.The aim of the present study was to detect Toxoplasma gondii in ticks collected from ponies and field vegetation and to determine the role of Shetland ponies as a potential reservoir host for T. gondii. A total of 1737 feeding Ixodes ricinus collected from 49 horses and 371 questing ticks were tested by PCR and sequencing for the presence and genotyping of T. gondii. All ticks were examined in a previous study to detect and identify pathogenic bacterial species. The aim of this study was also to detect co-infection of ticks with these bacteria and T. gondii. Genotyping of the sequenced B1 gene...
Izume S, Kirisawa R, Ohya K, Ohnuma A, Kimura T, Omatsu T, Katayama Y, Mizutani T, Fukushi H.Equine herpesvirus type 4 (EHV-4) is one of the most important pathogens in horses. To clarify the key genes of the EHV-4 genome that cause abortion in female horses, we determined the whole genome sequences of a laboratory strain and 7 Japanese EHV-4 isolates that were isolated from 2 aborted fetuses and nasal swabs of 5 horses with respiratory disease. The full genome sequences and predicted amino acid sequences of each gene of these isolates were compared with of the reference EHV-4 strain NS80567 and Australian isolates that were reported in 2015. The EHV-4 isolates clustered in 2 groups w...
Kobayashi D, Isawa H, Ejiri H, Sasaki T, Sunahara T, Futami K, Tsuda Y, Katayama Y, Mizutani T, Minakawa N, Ohta N, Sawabe K.Getah virus (GETV; genus Alphavirus, family Togaviridae) is a mosquito-borne virus known to cause disease in horses and pigs. In 2014, for the first time in ∼30 years, a sudden GETV outbreak occurred among racehorses in Ibaraki, Japan. Two years before this outbreak, we obtained multiple GETV isolates from Culex tritaeniorhynchus mosquitoes collected in Nagasaki, Japan and determined the whole genome sequence of GETV isolate 12IH26. Our phylogenetic analysis of GETV strains revealed that the isolate 12IH26 forms a robust clade with the epidemic strains 14-I-605-C1 and 14-I-605-C2 isolated fr...
Yao Q, Ma J, Wang X, Guo M, Li Y, Wang X.Tetherin (BST-2) is an important host restriction factor that can inhibit the release of a diverse array of enveloped viruses from infected cells. Conversely, to facilitate their release and spread, many viruses have evolved various strategies to overcome the antiviral effect of tetherin in a species-specific manner. During the development of an attenuated equine infectious anemia virus (EIAV) vaccine in our laboratory, we found that serial passage of a field-isolated virulent EIAV strains in horse and donkey as well as the cultivated donkey cells, produces several typical EIAV strains, includ...
Seo MG, Lee SH, Ouh IO, Lee GH, Goo YK, Kim S, Kwon OD, Kwak D.Members of the genus Coxiella can be transmitted from ticks to humans during contact with animals; Coxiella may thus spread from the infected horses or ticks to humans. In this study, the presence of Coxiella burnetii and Coxiella-like endosymbionts (CLE) in ticks found on infested horses was determined using PCR and genotyping. A total of 213 ticks were randomly collected from 51 horses (4-5 ticks per horse) raised on Jeju Island, Korea, between 2009 and 2013. All ticks were morphologically identified as adult Haemaphysalis longicornis, a predominant tick species widespread in Korea. Based on...
Ueno TE, Costa FB, Moraes-Filho J, Agostinho WC, Fernandes WR, Labruna MB.Rickettsia rickettsii is vectored by ticks, and some vertebrate hosts can be sources of infection to ticks during bacteremic periods. In Brazil, the main vector for R. rickettsii is the tick Amblyomma sculptum, a member of the A. cajennense complex. Horses, in turn, are one of the major hosts for A. sculptum. In this study, horses experimentally infected with R. rickettsii were assessed for clinical changes and their capability to transmit the infection to A. sculptum ticks. Four horses were infected with R. rickettsii through either intraperitoneal injection or infestation with R. rickettsii-...
Hlokwe TM, Sutton D, Page P, Michel AL.Tuberculosis caused by Mycobacterium bovis (M. bovis) is very uncommon in horses worldwide. Methods: In the current study, an eight-year-old male Thoroughbred in good body condition was admitted to the Equine Clinic at the Onderstepoort Veterinary Academic Hospital in 2005 due to bilateral epistaxis accompanied by coughing. Routine examinations were conducted to determine the cause of the condition. Endoscopic examination revealed the major source of the epistaxis as the trachea, whereas thoracic radiography indicated the presence of a primary pulmonary mass. M. bovis was isolated from a bronc...
Mirzai S, Safi S, Mossavari N, Afshar D, Bolourchian M.The present study was conducted to establish a Loop-mediated isothermal amplification (LAMP) technique for the rapid detection of B. mallei the etiologic agent of glanders, a highly contagious disease of equines. A set of six specific primers targeting integrase gene cluster were designed for the LAMP test. The reaction was optimized using different temperatures and time intervals. The specificity of the assay was evaluated using DNA from B.pseudomallei and Pseudomonas aeruginosa. The LAMP products were analyzed both visually and under UV light after electrophoresis. The optimized conditions w...
Shepard JJ, Andreadis TG, Thomas MC, Molaei G.Eastern equine encephalitis virus (EEEV) is a highly pathogenic mosquito-borne arbovirus, with active transmission foci in freshwater hardwood swamps in eastern North America, where enzootic transmission is maintained between the ornithophilic mosquito, Culiseta melanura, and wild passerine birds. The role of other locally abundant mosquito species in virus transmission and their associations with vertebrate hosts as sources of blood meals within these foci are largely unknown but are of importance in clarifying the dynamics of enzootic and epidemic/epizootic transmission. Blood-engorged mosqu...
Javed R, Taku AK, Gangil R, Sharma RK.The aim was to determine the occurrence of streptococci in equines in Jammu (R. S. Pura, Katra), characterization of Streptococci equi subsp. equi and Streptococcus equi subsp. zooepidemicus with respect to their virulence traits and to determine antibiotic sensitivity pattern of virulent Streptococcus isolates. Methods: A total of 96 samples were collected from both clinically affected animals (exhibiting signs of respiratory tract disease) and apparently healthy animals and were sent to laboratory. The organisms were isolated on Columbia nalidixic acid agar containing 5% sheep blood as well ...
van Spijk JN, Schmitt S, Fürst AE, Schoster A.Antimicrobial resistance has become an important concern in veterinary medicine. The aim of this study was to describe the rate of antimicrobial resistance in common equine pathogens and to determine the occurrence of multidrug-resistant isolates. A retrospective analysis of all susceptibility testing results from bacterial pathogens cultured from horses at the University of Zurich Equine Hospital (2012-2015) was performed. Strains exhibiting resistance to 3 or more antimicrobial categories were defined as multidrug-resistant. Susceptibility results from 303 bacterial pathogens were analyzed, ...
Pettengill MA, Lam VW, Ollawa I, Marques-da-Silva C, Ojcius DM.Ivermectin is currently approved for treatment of both clinical and veterinary infections by nematodes, including Onchocerca cervicalis in horses and Onchocerca volvulus in humans. However, ivermectin has never been shown to be effective against bacterial pathogens. Here we show that ivermectin also inhibits infection of epithelial cells by the bacterial pathogen, Chlamydia trachomatis, at doses that could be envisioned clinically for sexually-transmitted or ocular infections by Chlamydia.
Hilbert M, Csadek I, Auer U, Hilbert F.In the past, the horizontal transfer of antimicrobial resistance genes was mainly associated with conjugative plasmids or transposons, whereas transduction by bacteriophages was thought to be a rare event. In order to analyze the likelihood of transduction of antimicrobial resistance in the field of clinical veterinary medicine, we isolated phages from from a surgery suite of an equine clinic. In a pilot study, the surgery suite of a horse clinic was sampled directly after surgery and subsequently sampled after cleaning and disinfection following a sampling plan based on hygiene, surgery, and...
Lempereur L, Sohier C, Smeets F, Maréchal F, Berkvens D, Madder M, Francis F, Losson B.The dispersion potential of mechanical vectors is an important factor in the dissemination of pathogens. A mark-release-recapture experiment was implemented using two groups (unfed and partially fed) of the Tabanidae (Diptera) (Haematopota spp.) and biting Muscidae (Diptera) (Stomoxys calcitrans) most frequently collected in Belgium in order to evaluate their dispersion potential. In total, 2104 specimens of Haematopota spp. were collected directly from horses and 5396 S. calcitrans were collected in a cattle farm using hand-nets. Some of these insects were partially fed in vitro and all were ...
van Duijkeren E, van Asten AJ, Gaastra W.In the present study E. coli strains isolated from the faeces of ten horses with diarrhoea and 14 horses without diarrhoea were characterized. All horses were culture negative for Salmonella species. Nine colonies of E. coli from each faecal sample were picked at random and a DNA fingerprint was made by means of a polymerase chain reaction (PCR) using Enterobacterial Repetitive Intergenic Consensus (ERIC) primers. The number of E. coli genotypes did not differ significantly between horses with and without diarrhoea. In addition, all E. coli strains with different DNA fingerprints were tested b...
Adamson PJ, Wilson WD, Hirsh DC, Baggot JD, Martin LD.In vitro antimicrobic susceptibility patterns of commonly isolated aerobic gram-positive and gram-negative bacterial pathogens of equine origin were determined, using the agar-plate dilution method. All organisms were recent clinical isolates and included Corynebacterium (Rhodococcus) equi, Corynebacterium pseudotuberculosis, (coagulase positive) Staphylococcus sp, Streptococcus equi, Streptococcus zooepidemicus, Actinobacillus sp, Enterobacter cloacae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Salmonella. In vitro susceptibility levels were outlined for 14 antimicro...
Van Cleemput J, Poelaert KCK, Laval K, Van den Broeck W, Nauwynck HJ.The horse's respiratory tract daily encounters a plethora of respirable hazards including air pollutants, mycotoxins and airborne pathogens. To date, the precise effect of air pollution and mycotoxins on respiratory epithelial integrity and subsequent pathogen invasion in the horse has not been studied. Here, diesel exhaust particles (DEP) and three major mycotoxins (deoxynivalenol [DON], aflatoxin B1 [AFB1] and fumonisin B1 [FB1]) were applied to the apical surfaces of both ex vivo respiratory mucosal explants and in vitro primary equine respiratory epithelial cells (EREC) cultivated at the a...
Finley A, Gohari IM, Parreira VR, Abrahams M, Staempfli HR, Prescott JF.NetF-producing Clostridium perfringens have recently been identified as a cause of necrotizing enteritis in neonatal foals, but little is known about its prevalence in clinically normal foals. Foals (n = 88) ranging in age from < 1 wk to 2 to 4 mo (median age 2 to 4 wk) on 8 horse-breeding farms in Ontario were examined on 1 or 2 occasions for the presence of C. perfringens. Of the foals that tested positive, 5 isolates (n = 675) were examined for the netF and enterotoxin (cpe) genes. Colonization by C. perfringens was most marked in foals < 1 wk of age [4.85 ± 2.70 log10 colony-forming...
Al-Kass Z, Eriksson E, Bagge E, Wallgren M, Morrell JM.Stallion semen is known to contain environmental bacteria and normal commensals, and in some cases may contain opportunistic pathogens. These bacteria may negatively influence sperm quality during storage before artificial insemination. The bacteria isolated depend on the culture conditions and method of identification; therefore, the aim of this study was to identify as many of the bacteria present in stallion semen as possible by culturing aliquots of semen under a variety of conditions. Eleven semen samples were available: five extended semen samples from one stud together with a sample of ...
Baumann S, Gurtner C, Marti H, Borel N.Species of genus are important pathogens of animals, with a worldwide distribution and broad host range. Some species, such as , also pose a zoonotic disease risk. Abortion is one of the many diseases that has been associated with chlamydial infections in animals, with most attention focused on the economic impacts to sheep production. The role of chlamydia in equine abortions is unknown. Using the family-specific 23S ribosomal RNA (rRNA) real-time PCR, we tested 169 formalin-fixed, paraffin-embedded fetal membrane samples from 162 equine abortion cases collected between 2000 and 2018 in Swi...
Sanz MG, Oliveira AF, Page A, Horohov DW.Rhodococcus equi is the most common cause of pneumonia in young foals. A vaccine is not available and the use of R equi-specific hyperimmune plasma (HIP) is common. Despite its widespread use, the efficacy of HIP in preventing disease remains controversial. The objectives of this study were (1) to evaluate the virulence associate protein A (VapA)-specific IgG and IgG subclasses in commercially available R equi HIP and (2) to evaluate serum VapA-specific IgG and IgG subclasses in foals following administration of commercial R equi HIP. Three different lots from four commercial R equi HIP were s...
Ohta C, Hoshi A, Goto H, Tsunoda N, Tagami M, Akita H.Epizootiological and virological studies were conducted on foal diarrhea occurring in 3 foal-raising locations in a light horse farm from March to July, 1987. At the first location, although 27 (75%) of 36 foals had developed diarrhea, the isolation rate of rotavirus (RV) was low (5/14 feces, 36%). Many of the foals had the disease as early as 23 days after birth. At the second and third locations, 21 (27%) of 78 foals and 41 (76%) of 54 foals were affected with diarrhea. Isolation rates of RV were 90% (20/22 feces) and 100% (26/26 feces), respectively. The diseased cases were observed through...
Brooks DE, Andrew SE, Dillavou CL, Ellis G, Kubilis PS.To evaluate in vitro susceptibility to topical antifungal medications, as measured by minimum inhibitory concentration (MIC) and 50% inhibitory concentration (IC50%), of fungal isolates from horses with ulcerative keratomycosis in Florida; to compare results with those of other studies to identify differences in susceptibility patterns among fungi isolated from horses in different geographic regions; and to note indications of fungal resistance to drugs tested in other studies. Methods: Corneal fungal cultures from client-owned horses from Florida with ulcerative keratomycosis (n = 22). Method...
Fu X, Lindgren T, Guo M, Cai GH, Lundgren H, Norbäck D.There has been concern about the cabin environment in commercial aircraft. We measured cat, dog and horse allergens and fungal DNA in cabin dust and microbial volatile organic compounds (MVOCs) in cabin air. Samples were collected from two European airline companies, one with cabins having textile seats (TSC) and the other with cabins having leather seats (LSC), 9 airplanes from each company. Dust was vacuumed from seats and floors in the flight deck and different parts of the cabin. Cat (Fel d1), dog (Can f1) and horse allergens (Equ cx) were analyzed by ELISA. Five sequences of fungal DNA we...
Erol E, Scortti M, Fortner J, Patel M, Vázquez-Boland JA.Clonal multidrug resistance recently emerged in Rhodococcus equi, complicating the therapeutic management of this difficult-to-treat animal- and human-pathogenic actinomycete. The currently spreading multidrug-resistant (MDR) "2287" clone arose in equine farms upon acquisition, and coselection by mass macrolide-rifampin therapy, of the pRErm46 plasmid carrying the (46) macrolide-lincosamide-streptogramin resistance determinant, and of an mutation. Here, we screened a collection of susceptible and macrolide-resistant strains from equine clinical cases using a panel of 15 antimicrobials agains...
Sánchez-Matamoros A, Kukielka D, De las Heras AI, Sánchez-Vizcaíno JM.Cytokine secretion is one of the main mechanisms by which the immune system is regulated in response to pathogens. Therefore, the measurement of cytokine expression is fundamental to characterizing the immune response to infections. Real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR) is widely used to measure cytokine mRNA levels, but assay conditions should be properly evaluated before analyzing important equine infections through relative quantification of gene expression. The aim of this study was to develop and evaluate a set of RT-qPCR assays for a panel of th...
Takai S, Kawazu S, Tsubaki S.Humoral immune response to Rhodococcus equi in experimentally infected foals was studied with the enzyme-linked immunosorbent assay (ELISA) method. Class-specific antibodies were measured by ELISA in the sera of foals after intratracheal or oral inoculation with R. equi ATCC 6939 or T 48 and in the lung washings of a foal after intratracheal inoculation or of normal horses. After intratracheal or oral inoculation with R. equi, serum antibodies were first detected in immunoglobulin G (IgG) followed by IgM and IgA classes, but significant levels of IgM and IgA developed only in the foal infected...
Orsini JA, Soma LR, Rourke JE, Park M.The pharmacokinetics of amikacin sulfate (AK) were studied in the horse after intravenous (i.v.) and intramuscular (i.m.) administration. Serum (Cs), synovial (Csf) and peritoneal (Cpf) fluid concentrations of the drug were measured. Doses of 4.4, 6.6 and 11.0 mg/kg were given. The concentrations at 15 min following i.v. injection were 30.3 +/- 0.3, 61.2 +/- 6.9 and 122.8 +/- 7.4 micrograms/ml, respectively, for the 4.4, 6.6 and 11.0 mg/kg doses. Mean peak Cs values after the intramuscular injections occurred at 1.0 h post-injection and were 13.3 +/- 1.6, 23.0 +/- 0.6 and 29.8 +/- 3.2 microgra...
Hansson I, Johansson KE, Persson M, Riihimäki M.Nicoletella semolina, a member of the family Pasteurellaceae, can be isolated from the airways of horses with respiratory disorders. However, its role as a potential or opportunistic pathogen is not clear nor is its presence as part of the normal flora. We therefore investigated the presence and bacterial load of N. semolina in healthy and diseased horses. Samples from a healthy control group were compared with samples from the routine analysis of horses with a clinical history of respiratory disorders. A total of 1770 nose swabs and 1132 tracheal aspirate samples were analysed and subjected t...
Hunyadi L, Sundman EA, Kass PH, Williams DC, Aleman M.Immune-mediated myositis (IMM) is a cause of rhabdomyolysis, stiffness, and muscle atrophy predominantly affecting Quarter horses. Limited information is available with regard to outcome, prognostic indicators, and associations with concurrent diseases. Objective: To report outcomes and associations between outcome and clinical and laboratory parameters, and presence of concurrent illness. Methods: Sixty-eight horses; 52 Quarter horses and related breeds and 16 other breeds. Methods: Retrospective cohort study (1991-2014). Medical records of horses with histological diagnosis of IMM were revie...
Sydor T, von Bargen K, Becken U, Spuerck S, Nicholson VM, Prescott JF, Haas A.Rhodococcus equi is a mucoid Gram-positive facultative intracellular pathogen which can cause severe bronchopneumonia in foals and AIDS patients. A polysaccharide capsule which gives R. equi a mucoid appearance has long been suspected to be a virulence factor. Here, we describe a transposome mutant in the gene fbpA of strain R. equi 103 causing absence of a capsular structure. FbpA is a chromosomal gene homologous to antigen 85 (Ag85) mycolyl chain transferase gene of Mycobacterium tuberculosis. The mutant multiplied normally in isolated macrophages, was able to establish the unusual R. equi-c...
Sweeney CR, Benson CE, Whitlock RH, Meirs DA, Barningham SO, Whitehead SC, Cohen D.The age-specific attack rates of Streptococcus equi infections of the upper respiratory tract and lymph nodes (strangles) in horses for the different age groups were 17.6% for broodmares, 47.5% for 1-year-old horses, and 37.5% for foals. Streptococcus equi was isolated from nasal, pharyngeal, or lymph node specimens in 31 (60.8%) of 51 sick horses. A male 1-year-old horse, shipped from Kentucky to farm A, was considered to be the index case. Six (19.4%) of 31 horses with strangles remained as shedders of S equi after clinical signs of the disease had ended. Shedders of S equi were not identifi...
Mansfield LS, Mehler S, Nelson K, Elsheikha HM, Murphy AJ, Knust B, Tanhauser SM, Gearhart PM, Rossano MG, Bowman DD, Schott HC, Patterson JS.We tested the hypothesis that brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona, the agent of equine protozoal myeloencephalitis (EPM), and act as intermediate hosts for this parasite. In summer 1999, wild caught brown-headed cowbirds were collected and necropsied to determine infection rate with Sarcocystis spp. by macroscopic inspection. Seven of 381 (1.8%) birds had grossly visible sarcocysts in leg muscles with none in breast muscles. Histopathology revealed two classes of sarcocysts in leg muscles, thin-walled and thick-walled suggesting two species. Electron microscopy sh...
Kalinowski M, Jarosz Ł, Grądzki Z.Rhodococcus equi is an opportunistic, intracellular saprophyte that causes severe pyogranulomatous pneumonia in foals. The bacterium displays in vitro susceptibility to many antibiotics. The highest efficacy against R. equi in vitro and in vivo is achieved by using a combination of rifampicin and macrolide antibiotics. Recent years have seen an upward trend in the minimum inhibitory concentration (MIC) of rifampicin and erythromycin, suggesting increasing resistance of R. equi to these antibiotics. The aim of the study was to determine the antimicrobial activity of 24 selected antibiotics...
Schutzer SE, Schlater LR, Ronning CM, DeShazer D, Luft BJ, Dunn JJ, Ravel J, Fraser-Liggett CM, Nierman WC.Burkholderia mallei is an understudied biothreat agent responsible for glanders which can be lethal in humans and animals. Research with this pathogen has been hampered in part by constraints of Select Agent regulations for safety reasons. Whole genomic sequencing (WGS) is an apt approach to characterize newly discovered or poorly understood microbial pathogens. Results: We performed WGS on a strain of B. mallei, SAVP1, previously pathogenic, that was experimentally infected in 6 equids (4 ponies, 1 mule, 1 donkey), natural hosts, for purposes of producing antibodies. Multiple high inocula wer...
Ikhuoso OA, Monroy JC, Rivas-Caceres RR, Cipriano-Salazar M, Barbabosa Pliego A.Although the strangles disease of Streptococcus equi was discovered many decades ago in 1,251 by Jordanus Ruffus, it has still remained a major frequently diagnosed infection in horses all over the world. The S. equi subspecies pathogen is known to be often resistant to antibiotic treatment, and it makes the antibiotics inefficient; hence, this review was conducted to study how the disease can be managed. The age-long sign of this infection is the oozing of pus through the mucous and skin membranes. Affected horses lose appetite, develop fever, and become depressed, which result in them losin...
Voelter-Ratson K, Monod M, Unger L, Spiess BM, Pot SA.To characterize the conjunctival fungal flora and to determine the susceptibility of 2 isolated molds to antifungal drugs in samples of 64 healthy horses from The National Stud in Switzerland. Methods: Conjunctival cytobrush samples were collected from both eyes of 64 ophthalmologically normal horses in August 2012 and subsequently cultured on Sabouraud's agar medium. Growing fungi were identified and counted. Etests or broth microdilution tests for Aspergillus fumigatus and Eurotium amstelodami were carried out to determine antifungal drug sensitivity. These species had previously been detect...
Betbeze CM, Wu CC, Krohne SG, Stiles J.To evaluate the in vitro antifungal properties of silver sulfadiazine (SSD) and natamycin against filamentous fungi isolated from eyes of horses with keratomycosis. Methods: Filamentous fungal isolates obtained from eyes of keratomycosis-affected horses. Methods: Fungal culture of ocular samples yielded 6 Fusarium spp; 7 Aspergillus spp; and 1 isolate each of Curvularia, Scopulariopsis, Penicillium, and Chrysosporium. For each fungal isolate, minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of SSD and natamycin were determined. Results: For all 17 fungal isolat...
Rhodes DM, Magdesian KG, Byrne BA, Kass PH, Edman J, Spier SJ.Few studies report the minimum inhibitory concentrations for antimicrobials against equine Corynebacterium pseudotuberculosis isolates. Objective: To evaluate trends in the in vitro activities of 20 antimicrobials against equine Corynebacterium pseudotuberculosis isolates from 1996 to 2012 and to determine if a relationship exists between the minimum inhibitory concentration (MIC) and location of the abscess. Methods: Corynebacterium pseudotuberculosis isolates from 196 horses with naturally occurring disease. Methods: Retrospective and cross-sectional design. Medical records were reviewed to ...
Prescott JF.Current understanding of the epidemiology of Rhodococcus equi infection on horse farms is reviewed. Infection is widespread in herbivores and their environment, because herbivore manure supplies the simple organic acid substrates on which the organism thrives. There is a progressive development of infection in the soil on horse farms with prolonged use, because: (1) there is a continual supply of nutrients; (2) the organism multiplies progressively as temperatures rise; (3) the bacterium has a robust nature. While this aerobic organism fails to multiply in the largely anaerobic intestine of th...
Ibrahim ES, Kinoh M, Matsumura T, Kennedy M, Allen GP, Yamaguchi T, Fukushi H.Equine herpesvirus 1 was isolated from an onager in 1985, a zebra in 1986 and a Thomson's gazelle in 1996 in USA. The genetic relatedness and pathogenicity of these three viruses were investigated based on the nucleotide sequences of the glycoprotein G (gG) gene, experimental infection in hamsters, and comparison with horse isolates. The gG gene sequences of EHV-1 from onager and zebra were identical. The gG gene sequences of the gazelle isolate showed 99.5% identity to those of onager and zebra isolates. The gG gene sequences of EHV-1 isolated from horses were 99.9-100% identical and 98, 98 a...
