Streptococcus spp. are a genus of bacteria that can affect horses, leading to various infections and health conditions. These bacteria are known for causing respiratory and systemic diseases, including strangles, which is primarily caused by Streptococcus equi subsp. equi. Streptococcal infections in horses can result in symptoms such as fever, nasal discharge, and lymph node abscessation. The transmission typically occurs through direct contact with infected animals or contaminated environments. Diagnosis often involves bacterial culture or PCR testing. This page compiles peer-reviewed research studies and scholarly articles that explore the epidemiology, pathogenesis, diagnosis, and treatment of Streptococcus infections in equine populations.
Cheung AT, Liu IK, Walsh EM, Miller ME.The host defense competence of uterine-derived polymorphonuclear leukocytes (PMN) from mares considered resistant (grade I uteri) and susceptible (grade III uteri) to chronic endometritis was evaluated for phagocytic and killing (bactericidal) capacities, using a fluorochrome assay. Peripheral blood PMN from noncategorized mares and from grade I and grade III mares were used as controls. Uterine-derived PMN from mares with grade I uteri were functionally competent for phagocytosis and killing of Candida albicans, whereas uterine-derived PMN from mares with grade III uteri had significantly les...
Wilson WD, Baggot JD, Adamson PJ, Hirsh DC, Hietala SK.Sodium cefadroxil was administered as a single intravenous dose (25 mg/kg) to six healthy adult mares. Plasma samples were collected over a 24-h period and cefadroxil concentrations were measured by microbiological assay. The pharmacokinetic behavior of the drug was appropriately described in terms of a one-compartment open model. Values for the major pharmacokinetic terms were: extrapolated initial plasma concentration = 59.2 +/- 15.0 micrograms/ml; half-life = 46 +/- 20 min; apparent volume of distribution = 462 +/- 191 ml/kg; and body clearance = 7.0 +/- 0.6 ml/min.kg. In a subsequent study...
Timoney JF, Eggers D.An indirect test based on horse blood was used to study bactericidal responses of the horse to Streptococcus equi following infection or vaccination. Bactericidal antibody appeared in convalescent sera between two and four weeks and high titres were usually attained by eight weeks. Infection without clinical evidence of abscessation was also effective in eliciting strong bactericidal responses. Serum bactericidal activity of horses either recovered from strangles or immunised with commercial bacterin had declined eight months after vaccination. However, horses that developed strangles eight to...
Koblik PD, Lofstedt J, Jakowski RM, Johnson KL.Indium 111-labeled autologous leukocytes were used to image an abdominal abscess in a horse with a palpable abdominal mass and history of Streptococcus equi infection. A focal area of radioactivity was identified in the location corresponding to the abscess. Imaging of this focal uptake was optimal 48 hours after injection. Similar scans obtained in 2 clinically normal horses revealed no evidence of focal radioactivity in this region. The cell labeling procedure gave acceptable labeling efficiency (87.5%) but an excessive number of damaged WBC, resulting in persistent lung radioactivity on all...
Bannister MF, Benson CE, Sweeney CR.Two commercial systems, the API 20S (Analytab Products, Plainview, N.Y.) and the Rapid Strep (API System S.A., Montalieu-Vercieu, France), were evaluated for ease of use and accuracy in the rapid identification of group C streptococci isolated from horses. A total of 85 Streptococcus isolates were tested, including S. equi (67 isolates), S. zooepidemicus (13 isolates), and S. equisimilis (5 isolates). All S. equi and S. zooepidemicus isolates were correctly identified within 24 h by the Rapid Strep system. Specific grouping sera was necessary to distinguish between S. equisimilis and group G o...
Liu IK, Cheung AT, Walsh EM, Miller ME, Lindenberg PM.The functional competence of peripheral blood and uterine-derived polymorphonuclear leukocytes (PMN) from 12 mares were analyzed for chemotactic responsiveness using a chemotactic chamber (filter) assay and for deformability by cell elastimetry analysis. Peripheral blood PMN obtained from control mares and from 8 mares experimentally inoculated via the uterus with 1 x 10(9) Streptococcus zooepidemicus had similar normal chemotactic responsiveness and were highly deformable before and at 12 hours after inoculation. Uterine PMN obtained 12 hours after uterine inoculation with S zooepidemicus fro...
Timoney JF, Trachman J.Immunologically reactive proteins in acid extracts and culture supernatants of Streptococcus equi were recognized through a combination of chromatographic and immunologic procedures. Both high- and low-molecular-weight components of each of these protein preparations were protective for mice and were, therefore, presumed to contain a variety of hydrolytic products or fragments of the M protein of S. equi. Convalescent horse sera that exhibited strong bactericidal activity for S. equi always reacted with polypeptides in the molecular weight range of 24,000 to 29,000, whereas preinfection sera d...
Balke E, Weiss R, Seipp A.A total of 110 strains of beta-hemolytic streptococci, belonging to serogroup C (Lancefield), isolated from horses (71 S. zooepidemicus, 27 S. equisimilis and 12 S. equi) as well as 5 reference strains were tested for their ability to produce hyaluronidase. The determinations were carried out in a culture test on agarose gel and in a liquid test system (turbidity test according to DiFerrante). The results of both methods used showed that the three Streptococcus species could be differentiated by the relative quantitative determination of hyaluronidase activity. S. equisimilis strains produce 5...
Galan JE, Timoney JF.Mucosal nasopharyngeal immunoglobulin A (IgA) and IgG responses to proteins of Streptococcus equi were studied in horses after the experimental production of strangles. S. equi-specific IgA and IgG titers in nasopharyngeal mucus were much higher in samples from animals 1 to 2 weeks after challenge than in samples from control animals. Although IgA was the major immunoglobulin in nasal mucus, there was more antibody activity associated with IgG as measured by radioimmunoassay. Great differences between the specificities of antibodies in nasal mucus and in serum were detected. IgA and IgG of muc...
Srivastava SK, Barnum DA, Prescott JF.The production of M-protein antigen of Streptococcus equi was studied during in vitro growth in equine blood and in various media. Of 11 S equi strains studied, seven which had initially possessed 0.04 mg or less M-protein per 10 mg of streptococcal cell extract showed an increase in M-protein content after successive culture in heparinised horse blood. Maximum proliferation occurred in Todd-Hewitt (TH) medium with added 0.2 per cent w/v glucose when compared with TH medium alone or TH medium with 2 per cent w/v sucrose, starch, neopeptone or normal horse serum. The M-protein of these strains ...
Rigg DL, Ramey DW, Reinertson EL.Respiratory distress and laryngeal paralysis were found to be caused by a Streptococcus equi abscess of cranial mediastinal lymph nodes, putting pressure on the trachea at the thoracic inlet. Surgical drainage was required to relieve the compression, and long-term antibiotic therapy was used to treat the bacterial infection. The trachea returned to normal diameter but left laryngeal hemiplegia persisted. Peritracheal abscesses should be considered in the differential diagnosis of inspiratory dyspnea of the horse.
Baggot JD, Love DN, Rose RJ, Raus R.The serum concentrations of the aminoglycosides neomycin, kanamycin and streptomycin were determined after intravenous (iv) and intramuscular (im) administration. These values were then related to the minimum inhibitory concentrations (MIC) of a number of equine pathogenic bacteria to determine the duration of therapeutic serum concentrations of the aminoglycosides in the horse. Pharmacokinetic analysis of the data using neomycin as the example revealed a mean (+/- sd) peak serum concentration of 23.2 +/- 10.2 micrograms/ml present at 30 mins, and at 8 h the serum concentration was 2.8 +/- 0.8...
Benson CE, Sweeney CR.Streptococcus pneumoniae type 3 was isolated from seven tracheobronchial aspirates and one pleural tap of seven adult horses and one foal. There was no direct evidence in these horses that isolation of the pneumococcus was related to a specific disease syndrome. Presenting complaints included two horses with chronic cough, two horses with decreased exercise tolerance, one horse with exercise-induced pulmonary hemorrhage, and three horses with pneumonia. Antibiotic therapy resolved the primary clinical complaint. This is the first report of the isolation of S. pneumoniae type 3 from adult horse...
Higgins R, Biberstein EL, Jang SS.Of 24 isolates of nutritionally variant streptococci recovered from equine corneal ulcers, 22 were tested for growth requirements, physiological and biochemical reactions, and susceptibility to different antimicrobial agents. Satisfactory growth was obtained by supplementing blood agar and Todd-Hewitt broth with pyridoxal hydrochloride, and all of the media for the culture and the biochemical testing were supplemented with 0.002% of this substance. Biochemical patterns of 12 of the isolates resembled those of two viridans streptococcal species, Streptococcus intermedius and Streptococcus const...
Tzipori S, Hayes J, Sims L, Withers M.Streptococcus durans was isolated from a foal with profuse watery diarrhea and caused a similar syndrome when inoculated into foals via the orogastric route. The most consistent and striking histological feature was the extensive colonization of the mucosal surface of the small intestine by S. durans. Associated mucosal changes were mild to modeate, and brush border lactase and alkaline phosphatase production were depressed. S. durans also induced acute diarrhea in young gnotobiotic piglets. Mucosal changes were mild and, as with foals, the mucosal surface of the small intestine was colonized ...
Varma KJ, Powers TE, Powers JD, Spurlock SL.A reproducible experimental disease model in horses using Streptococcus zooepidemicus was developed. An intravenous challenge dose of 1 X 10(10) colony-forming units (CFU), followed 24 h later with another challenge of 1 X 10(8) CFU of Strep. zooepidemicus produced the desired disease model. The disease was characterized by depression, pyrexia, anorexia, abnormal lung sounds, inflammation of joints, moderate to severe lameness, gradual loss of condition and emaciation. The effects of the disease on hematology, serum chemical profile and different protein fractions were studied. The disease sta...
Powers JD, Powers TE, Varma KJ, Gabel AA, Spurlock SL.Quantification of the clinical manifestations of a disease has been a serious problem particularly as related to clinical trials or drug efficacy studies. Historically, this quantification has been limited to categorizing each patient into one of three or four groups, e.g. worse, no improvement, improved. This problem becomes serious when an investigation utilizes an experimentally induced animal disease model. A health index, which quantifies the clinical state of horses which have an experimentally induced beta-hemolytic streptococcal infection, is described. Aspects of experimental design a...
Asbury AC, Gorman NT, Foster GW.The addition of serum to uterine secretions was shown to opsonize Streptococcus zooepidemicus and significantly enhance bacterial phagocytosis by equine neutrophils. Treatment of serum by heat inactivation at 56 degrees C, EDTA treatment, and C3 consumption reduced phagocytosis and therefore demonstrated that the process was complement-dependent. The amount of C3 present in uterine secretions was measured in a series of 14 mares infected with Streptococcus zooepidemicus . Ten of the 14 mares had detectable amounts of C3; however, the C3 had been cleaved and rendered nonfunctional. The importan...
Piché CA.An outbreak of strangles, which occurred during the spring, summer and fall of 1980 on a Standardbred stud farm in eastern Alberta is described. The infective organism, Streptococcus equi, may have been introduced by an outside mare that was brought to the stud for breeding. All of the groups of horses on the farm were affected. For the most part, the disease was allowed to run its natural course. Only severely affected individuals were treated. During the outbreak, the foals were prophylactically treated with penicillin to prevent them from contracting the disease. Ten horses died of complica...
Srivastava SK, Barnum DA.Streptococcus equi was found to adhere to tongue, cheek and nasal epithelial cells of ponies, in vitro. Maximum adherence was observed at pH 7.5 after one hour of incubation of bacteria with epithelial cells. This adherence was more on epithelial cells from adult animals than from foals. Streptococci exposed to heat (60 degrees C for 10 min) or treated with pepsin or trypsin showed a reduced adherence, whereas an increase occurred on treatment with hyaluronidase. Antibodies against whole S. equi cells or M-like protein blocked the adherence, whereas antibodies against group-specific carbohydra...
Ducharme NG, Dill SG, Shin SJ, Schwark WS, Ducharme GR, Beilman WW.This preliminary study evaluated phenoxymethyl penicillin (Penicillin V) as an alternative to parenteral administration of penicillin in horses. Penicillin V was administered orally to five horses at two different doses and plasma levels of the drug were determined at timed intervals. The results were evaluated by regression analysis. Following the administration of penicillin V at a dose of 66,000 IU/kg or 110,000 IU/kg, the mean peak plasma levels obtained were 1.55 micrograms/mL and 2.34 micrograms/mL respectively. A plasma level two to four times above the minimal inhibitory concentration ...
George JL, Reif JS, Shideler RK, Small CJ, Ellis RP, Snyder SP, McChesney AE.During an outbreak of strangles in a population of research horses, 4 mares were identified as carriers of Streptococcus equi. Three of the mares had typical signs of strangles (severe regional lymphadenitis with or without rupture of abscessed lymph nodes). The 4th mare experienced episodes of serous to mucopurulent nasal discharge, but never had more than a mild degree of lymph node enlargement. Streptococcus equi was isolated from the abscessed lymph nodes and from nasopharyngeal swab specimens from the first 3 mares from 6 to 19 weeks after rupture of involved nodes. Streptococcus equi was...
Nara PL, Krakowka S, Powers TE, Garg RC.Fourteen young outbred horses, divided into 2 groups on the basis of 18- or 24-hour skin-test reactions to Streptococcus equi, were inoculated nasopharyngeally with virulent S equi. Animals (n = 6, group I) with evidence of previous exposure to S equi (positive dermal response and existing serum antibodies), with one exception, developed minimal or no signs of disease after inoculation. In contrast, S equi skin-test negative and seronegative horses (n = 8, group II) developed predictable and severe clinical signs of infection after their inoculation, including shedding of the organism from nas...
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.
Lämmler C, Chhatwal GS, Blobel H.Binding of 125I-labelled fibrinogen from humans, bovines, equines, canines and ovines by streptococci of serological groups A, B, C and G was determined quantitatively. All 59 randomly selected streptococcal cultures generally bound more human fibrinogen than the other fibrinogens. Only Sc. dysgalactiae had a higher affinity for bovine fibrinogen. In addition, Sc. dysgalactiae bound distinctly more equine, canine and ovine fibrinogen than the other streptococci. Some cultures of Sc. equi and Sc. zooepidemicus had high binding activities for equine fibrinogen. Low binding capacities were exhibi...
Marcum JA, Highsmith RF, Kline DL.Complete activation of purified horse plasminogen to plasmin was obtained with a 1:10 molar ratio of streptokinase to plasminogen after 5 min of incubation at 37 degrees C. At a 1:1 molar ratio, maximal activity did not appear until 15-30 min, while at a ratio of 6:1 complete activation was delayed for 120-180 min. Gel filtration studies of isotopically labeled streptokinase and horse plasminogen suggest that the delay was due to impaired formation of a streptokinase-plasminogen complex. The predominant streptokinase moiety within the streptokinase-plasmin complex which forms from the streptok...
Prescott JF, Srivastava SK, deGannes R, Barnum DA.A mild form of strangles caused by an atypical Streptococcus equi was recognized on a large horse breeding farm. The organism differed from most S equi isolates by disappearance of the mucoid capsule by 24 hours of culture, leaving a matt-type colony. Typically, the clinical signs were a transient (24-48 hour) fever, profuse nasal discharge, and anorexia. In about half the affected animals, there was moderate mandibular lymph node enlargement, and these glands usually ruptured or were drained. The use of a passive hemagglutination antibody test showed that subclinical infection was widespread ...
Durham AE, Kemp-Symonds J.Serology is commonly used as a means of identifying horses that might be chronic and silent carriers of S. equi but its sensitivity is rarely examined. Objective: The study was designed to investigate the sensitivity of serological testing for antibodies against S. equi antigens A and C to detect guttural pouch carriers of S. equi. Methods: Retrospective clinical study. Methods: As part of routine surveillance and quarantine procedures horses arriving at a welfare charity quarantine unit were subject to both microbiological sampling of guttural pouches and also serological testing for antibo...
Jaramillo-Morales C, Gomez DE, Renaud D, Arroyo LG.The objectives of this study were to determine the prevalence of S. equi in a horse population in Colombia, to determine the risk factors associated with its detection in the guttural pouches and to report the antimicrobial susceptibility of the isolates. Fifteen farms and 137 horses >6 months of age were enrolled. Sampling was randomly, stratified and proportional to the population size of each farm. The guttural pouch (GP) was swabbed via endoscopic guidance and culture was performed. DNA extraction and conventional PCR were performed in colonies compatibles with S. equi, the PCR products we...
Ledbetter EC, Scarlett JM.To determine the frequency of obligate anaerobic bacterial isolation from corneal samples of domestic animals with ulcerative keratitis and to characterize the historical, clinical, cytological, and microbiological features of culture-positive cases. Methods: Three hundred and thirty domestic animals with ulcerative keratitis. Methods: Anaerobic bacteriologic culture and Gram stain were performed on corneal samples from consecutive animals examined with suspect septic ulcerative keratitis. Additional corneal diagnostics included: aerobic bacteriologic culture for all species; fungal culture fo...
Podico G, Gray SM, Wang L, Canisso IF.An 8-y-old jenny was presented because of anorexia and mild depression. The jenny had weaned her colt 10 d before the admission. Upon arrival at the University of Illinois Veterinary Teaching Hospital, the heart rate was elevated, and the right udder was painful and swollen on palpation. Milk stripping of the affected side revealed purulent content; the contralateral udder had normal-appearing milk. Cytology of mammary gland secretions from the affected side revealed a large number of hypersegmented reactive neutrophils with phagocytized bacteria. Complete blood count, serum chemistry, and f...
Acke E, Midwinter AC, Lawrence K, Gordon SJ, Moore S, Rasiah I, Steward K, French N, Waller A.To estimate the prevalence of β-haemolytic Lancefield group C streptococci in healthy dogs, cats and horses; to determine if frequent contact with horses was associated with isolation of these species from dogs and cats; and to characterise recovered S. equi subsp. zooepidemicus isolates by multilocus sequence typing. Methods: Oropharyngeal swabs were collected from 197 dogs and 72 cats, and nasopharyngeal swabs from 93 horses. Sampling was carried out at the Massey University Veterinary Teaching Hospital, on sheep and beef farms or on premises where horses were present. All animals were heal...
Srivastava SK, Barnum DA.The ability of either formalin-treated or heat-inactivated whole Streptococcus equi cell vaccines or partially purified M-protein of S. equi to give rise to protective antibody levels was studied in Standardbred foals by serological means. Two commercial preparations, i.e. a beta-propiolactone killed whole S. equi cell bacterin and a cell-free extract of S. equi cells were included in the study. The mean passive hemagglutination antibody titers (10 X log2) in sera of foals given either four doses of formalin-treated whole cell vaccine or an initial dose of formalin-treated followed by three do...
Riihimäki M, Aspán A, Ljung H, Pringle J.The aim of the study was to use culture, qPCR and seM sequencing to map Streptococcus equi subspec. equi (S.equi) isolates in long term carrier animals. A strangles outbreak affecting 41 Icelandic horses was followed to determine strangles free status using nasal and/or guttural pouch lavages collected serially on eleven separate occasions over 13 months. Ten persistent carriers, of which eight had repeated culture positive samples for S. equi, were selected for the study. Of 115 samples collected, 61 were S. equi positive on qPCR; from which 32 were also culture positive. Amplification of par...
Urosevic M, Lako B, Milanov D, Urosevic I, Aurich C.Uterine microbiology, antimicrobial susceptibility and endometrial cytology were investigated in a total of 51 mares with fertility problems from 16 different stud farms in Serbia. Uterine cultures were performed after collection with a double guarded uterine swab, and endometrial cytology was evaluated after collection of endometrial cells with a special device (cytology brush). In 21 of 51 mares, at least one bacterial species was isolated from the uterus; the most frequent were Streptococcus equi subsp. zooepidemicus (13 isolates) and E. coli (four isolates). All isolates of Streptococcus e...
Dalgleish R, Love S, Pirie HM, Pirie M, Taylor DJ, Wright NG.A natural outbreak of strangles occurred in a group of 19 young experimental ponies. The disease was diagnosed in 11 of them within two days of their arrival at Glasgow University veterinary school and five others developed clinical signs within a further four days, a morbidity rate of 84 per cent. All of the affected ponies had typical signs of strangles including dullness, anorexia, pyrexia, regional lymphadenitis, occasionally with rupture of the lymph node, conjunctivitis and a mucopurulent nasal discharge. Nine of the affected ponies were destroyed during the clinical phase of the disease...
Jacobi S, Townsend WM, Bolin CA.To evaluate whether equine serum administered via a simulated subpalpebral lavage system (SPL) supports proliferation of Streptococcus zooepidemicus or Pseudomonas aeruginosa within the tubing. Methods: A sterile i.v. catheter with injection cap was inserted into sterilized silicone tubing (Mila). To mimic an SPL within the dorsal conjunctival fornix, the tubing was secured to an elevated platform. The tip of the tubing extended from the platform into a vial containing culture medium just inoculated with approximately 1.5 x 10(8) CFU/mL P. aeruginosa or S. zooepidemicus. To mimic administratio...
Poulin MF, Boivin G.Human infections with Streptococcus equi subspecies zooepidemicus, a group C streptococcus, are very rare and are generally associated with contact with horses, and consumption of unpasteurized milk products, goat cheese or pork. In most cases S zooepidemicus leads to fulminant infections. The case of a middle-aged woman who had sporadic contact with horses is described in the present report. She developed a bacteremia with severe and extensive complications that included meningitis, mitral endocarditis and blindness due to bilateral endophthalmitis. To the authors' knowledge, this is the firs...
Ducharme NG, Dill SG, Shin SJ, Schwark WS, Ducharme GR, Beilman WW.This preliminary study evaluated phenoxymethyl penicillin (Penicillin V) as an alternative to parenteral administration of penicillin in horses. Penicillin V was administered orally to five horses at two different doses and plasma levels of the drug were determined at timed intervals. The results were evaluated by regression analysis. Following the administration of penicillin V at a dose of 66,000 IU/kg or 110,000 IU/kg, the mean peak plasma levels obtained were 1.55 micrograms/mL and 2.34 micrograms/mL respectively. A plasma level two to four times above the minimal inhibitory concentration ...
Klohnen A, Wilson DG, Hendrickson DA, Cooley AJ, MacWilliams PS.To evaluate the bactericidal properties of chlorhexidine diacetate (CHD) after potentiation with EDTA and Tris buffer (EDTA-Tris), and to find a potentiated CHD concentration that would achieve 90 to 100% killing for all bacteria tested. Methods: 6 adult ponies. Methods: Serial dilutions of CHD, CHD in EDTA-Tris and EDTA-Tris alone were evaluated for bactericidal activity against Staphylococcus aureus, Escherichia coli, and Streptococcus zooepidemicus. The tarsocrural joints of 6 ponies were lavaged with either 1 L phosphate-buffered saline solution (control) or 1 L of 0.0005% CHD in EDTA-Tris...
Newton JR, Wood JL, Dunn KA, DeBrauwere MN, Chanter N.During an outbreak of strangles on a farm with approximately 1500 horses, the spread of Streptococcus equi infection was monitored by repeated nasopharyngeal swabbing and culture. In order to control the infection and prevent new introductions of strangles on to the premises, a system of quarantine and swabbing of cases and all incoming animals was instituted. Long-term carriage of the organism was detected in four clinically healthy convalescent animals, and in two of 350 new ponies; it persisted for between seven and 39 months, but it was detected only intermittently by the culture of swabs ...
Harvey A, Kilcoyne I, Byrne BA, Nieto J.To compare synovial concentrations of amikacin following intravenous regional limb perfusion (IVRLP) with two different doses, and to compare their ability to reach target concentrations for bacterial isolates from common orthopedic conditions. Methods: Randomized crossover experiment. Methods: Six adult horses. Methods: Horses received IVRLP with 2 and 3 g of amikacin in the cephalic vein of alternate limbs (20 minutes tourniquet application and ≥14 days washout period). Amikacin concentrations were quantified in synovial fluid collected from the middle carpal and metacarpophalangeal joints...
Duchesne R, Castagnet S, Maillard K, Petry S, Cattoir V, Giard JC, Leon A.This study aimed to analyse antimicrobial susceptibility evolution of equine pathogens isolated from clinical samples from 2006-2016. A collection of 25 813 bacterial isolates was studied, clustered according to their origins (respiratory tract, cutaneous, genital and other), and analysed for their antimicrobial susceptibility using the disk diffusion method. The most frequently isolated pathogens were group C Streptococci (27.6%), Escherichia coli (20.0%), Staphylococcus aureus (7.8%), Pseudomonas aeruginosa (4.0%), Enterobacter spp. (3.4%), Klebsiella pneumoniae (2.4%), and Rhodococcus equi ...
Bourély C, Cazeau G, Jarrige N, Haenni M, Gay E, Leblond A.Horses are one of the potential reservoirs of antimicrobial resistance (AMR) determinants that could be transferred to human subjects. Objective: To describe the AMR patterns of major bacteria isolated from diseased horses in France. Methods: Retrospective observational study. Methods: Data collected between 2012 and 2016 by RESAPATH, the French national surveillance network for AMR, were analysed. Only antimicrobials relevant in veterinary and human medicine for the isolated bacteria were considered. Mono- and multidrug resistance were calculated. The resistance proportions of major equine di...
McDonnell AM, Watson ED.Four pony mares were used in a cross-over study to investigate the effect of different treatments on experimentally-induced endometritis. The mares were treated with progesterone to facilitate establishment of uterine infections. They received an intrauterine infusion of Streptococcus zooepidemicus 5 days after the start of progesterone therapy. Five days later, they were treated by intrauterine infusions of 2 g ampicillin in 50 ml sterile water or by sterile water without antibiotic for 3 consecutive days. Prior to infusion of Strep. zooepidemicus, no bacteria were cultured from the uteri of ...
Panchaud Y, Gerber V, Rossano A, Perreten V.Bacterial infections present a major challenge in equine medicine. Therapy should be based on bacteriological diagnosis to successfully minimize the increasing number of infections caused by multidrug-resistant bacteria. The present study is a retrospective analysis of bacteriological results from purulent infections in horses admitted at the University Equine Clinic of Bern from 2004 to 2008. From 378 samples analyzed, 557 isolates were identified, of which Staphylococcus aureus, Streptococcus equi subsp. zooepidemicus and coliforms were the most common. Special attention was paid to infectio...
Chanter N, Collin N, Holmes N, Binns M, Mumford J.The 16S-23S RNA gene intergenic spacers of isolates of Streptococcus equi (n = 5), S. zooepidemicus (n = 5), S. equisimilis (n = 3) and S. dysgalactiae (n = 2) were sequenced and compared. There were distinct regions within the spacer, arranged in the order 1-9 for all S. equi and one S. zooepidemicus isolate and 1,2 and 4-9 for the remaining isolates. Region 4 was identical to the tRNA(ala) gene found in the 16S-23S intergenic spacers of other streptococci. Regions 1, 5, 6 and 7 had distinct variations, each conserved in different isolates. However, amongst the intergenic spacers there were d...
Von Dollen KA, Jones M, Beachler T, Harris TL, Papich MG, Lyle SK, Bailey CS.The use of antimicrobials for the management of equine uterine disease is commonplace, with antibiotic selection generally based on empirical evidence or in vitro sensitivity results. However, the potential disconnect between these laboratory results and clinical efficacy in the mare raises concern for antibiotic failure and subsequent development of resistant organisms. In this work, we attempt to bridge this gap by using an ex vivo model of the equine postpartum uterus to quantitatively evaluate the antimicrobial activity of two commonly used antibiotic treatments in the mare (ceftiofur an...
Oikawa M, Kamada M, Yoshikawa Y, Yoshikawa T.Seven horses that died of pneumonia associated with transport yielded Streptococcus equi subsp. zooepidemicus (S.z.) from their pulmonary lesions. These lesions were divisible roughly into two types, serous haemorrhagic pneumonia and multiple foci of coagulative necrosis, which were considered to reflect a temporal difference in the process of lesion formation. Immunohistologically, S.z. antigen was detected in both types of lesion. Acute necrotic lacunar tonsillitis was considered to play an important role in the onset of the pneumonia.
Jacks SS, Giguère S, Nguyen A.The objective of this study was to determine in vitro activities of azithromycin (AZM), clarithromycin (CLR), and 20 other antimicrobial agents against Rhodococcus equi and other common equine bacterial pathogens. A total of 201 bacterial isolates from various equine clinical samples were examined. CLR was more active than AZM against R. equi, with MICs at which 90% of the isolates were inhibited of 0.12 and 1.0 micro g/ml, respectively. Other antimicrobial agents highly active against at least 90% of R. equi isolates in vitro included rifampin, gentamicin, and imipenem. Both AZM and CLR showe...
Lord J, Carter C, Smith J, Locke S, Phillips E, Odoi A.Surveillance of antimicrobial resistance (AMR) among veterinary pathogens is necessary to identify clinically relevant patterns of AMR and to inform antimicrobial use practices. Streptococcus equi subsp. zooepidemicus and Rhodococcus equi are bacterial pathogens of major clinical importance in horses and are frequently implicated in respiratory tract infections. The objectives of this study were to describe antimicrobial resistance patterns and identify predictors of AMR and multidrug resistance (MDR) (resistance to three or more antimicrobial classes) among equine S. zooepidemicus and R. equi...
Lannergård J, Frykberg L, Guss B.Streptococcus equi subspecies equi is an important horse pathogenic bacterium causing a serious disease called strangles. Using bioinformatics we identified a gene denoted cne (gene encoding collagen-binding protein from S. equi) coding for a novel potential virulence factor of this species called protein CNE. The protein is composed of 657 amino acids and has the typical features found in cell surface-anchored proteins in Gram-positive bacteria. CNE displays amino acid sequence similarities to the previously well-studied collagen-binding protein CNA from Staphylococcus aureus, a proven virule...
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.
Zhang H, Zhou T, Su L, Wang H, Zhang B, Su Y.Strangles, which is caused by Streptococcus equi subspecies equi (S. equi), is one of the most prevalent equine infectious diseases with worldwide distribution and leads to serious economic loss in the horse industry. Sortase A (srtA) is a transpeptidase that anchors multiple virulence-associated surface proteins to the cell surface of S. equi. srtA plays a major role in S. equi infection and colonization of the host cell. In this study, we aimed to investigate the effects of srtA mutation on the phagocytic activity and immunogenicity of S. equi. The point-mutated recombinant sortases, includi...
Lanka S, Borst LB, Patterson SK, Maddox CW.The objective of the present investigation was to differentiate between strains of Streptococcus equi subspecies equi implicated in abscess formation in vaccinated horses. Streptococcus equi isolates recovered from clinical specimens associated with equine strangles cases submitted to the University of Illinois Veterinary Diagnostic Laboratory were compared with S. equi isolates representing at least 12 lots of a commercial modified live vaccine (MLV) to determine whether the isolates obtained from the abscesses were vaccine or wild type. Genotyping techniques evaluated included enterobacteria...
Hobo S, Niwa H, Anzai T, Jones JH.In this study, to evaluate the influence of strangles vaccination on serological test results, we investigated the changes in strangles serum antibody levels in horses after vaccination and subsequent intranasal challenge with S. equi. The horses were vaccinated for strangles with either a component vaccine (Group C) or a live vaccine (Group L). We measured changes in strangles serum antibody levels weekly for 20 weeks after vaccinating horses twice for strangles over a 3-week interval, and for 7 weeks after intranasal challenge with S. equi in the same horses. Serum antibody responses to the ...
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...
