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.
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 ...
Blue MG, Brady AA, Davidson JN, Kenney RM.Forty uterine fluid samples were obtained during oestrus and dioestrus of successive cycles from 4 mares classified as resistant to bacterial infection of the uterus. The flushings were assayed for peroxidase activity and ability to influence phagocytosis by polymorphonuclear neutrophils. Uterine fluid volumes and protein concentrations and serum oestrogen values were similar during oestrus and dioestrus. Serum progesterone concentrations were depressed during oestrus. Equine neutrophils adherent to glass slides were exposed to a genital strain of Streptococcus zooepidemicus suspended in salin...
Srivastava SK, Barnum DA.Lymphocyte stimulation was observed in whole equine blood in the presence of phytohaemagglutinin and M protein extracted from a typical strain of Streptococcus equi. Blood samples were collected from several healthy horses and horse and pony foals and cultured in vitro with varying concentrations of phytohaemagglutinin and M protein for several days. Phytohaemagglutinin was found to induce lymphocyte stimulation in these animals. Highest mean stimulation indices in horse foals (49.3 +/- 24.4) and pony foals (54.7 +/- 32.0) were observed with 0.625 and 1.25 micrograms/mL phytohaemagglutinin, re...
Ganjam VK, McLeod C, Klesius PH, Washburn SM, Kwapien R, Brown B, Fazeli MH.The reaction between ovarian hormones and experimental uterine infection (Streptococcus zooepidemicus) was investigated in 3 groups, each containing 6 ovariectomized mares. Group 1 served as controls ('anoestrus'), Group 2 mares were injected with oestrogen ('oestrus') and Group 3 with progesterone ('dioestrus') over a period of 5 weeks. All mares received an intrauterine inoculation of the bacteria 1 week after the start of hormonal treatment, and the results of the challenge were examined by endometrial biopsy and swabs once weekly. At the end of Week 1 no bacteria were recovered from the ma...
Srivastava SK, Barnum DA.A group of 100 foals was given either a commercial bacterin or an autogenous vaccine consisting of whole cells and an acid extract of Streptococcus equi. During the study, some of the foals developed clinical strangles. Various sets of sera were collected from these foals prevaccination, during vaccination, postvaccination and postinfection. The serological response of these foals was measured by passive haemagglutination and long chain tests. In foals which remained healthy, the highest titres were reached within one to two months postvaccination with a passive haemagglutination 10 x log2 mea...
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 ...
Rumbaugh GE, Smith BP, Carlson GP.internal abdominal abscesses in 25 horses, including 8 horses that died or were euthanatized, were found to be caused by Streptococcus equi, Streptococcus zooepidemicus, or Corynebacterium pseudotuberculosis. Breed or sex predilection was not found. Although horses of all ages were affected, those under 5 years of age were more commonly affected. Nearly all of the horses had a history of respiratory catarrh or lymphadenitis. Horses with internal abdominal abscesses also had intermittent, prolonged colic or chronic weight loss. Most horses had increased rectal temperature, increased heart and r...
Pine L, Reeves MW.Various sugars were tested for their effect on the differential rate of synthesis of M protein during the growth of Streptococcus pyogenes strain 0055 M12T12. In a semisynthetic medium alone, a high rate of M protein synthesis occurred with glucose as a substrate; decreasing rates of synthesis occurred with sucrose and trehalose, in that order, although the rates of growth were approximately equal with all sugars. A period of derepressed synthesis of M protein occurred in the lag phase of growth and in the stationary period as the substrates were being depleted. Although glucose inhibited the ...
Gunson DE, Rooney JR.An 8-year-old gelding with a long-standing, streptococcal respiratory infection developed dyspnoea and colic. Laparotomy disclosed numerous, discrete, hemorrhagic, thick areas of necrosis throughout the intestinal tract. At postmortem examination similar lesions were seen in the laryngeal mucosa and in many skeletal muscles. Microscopically these lesions had massive necrosis and hemorrhage with a leucocytoclastic vasculitis in adjacent tissue. This condition resembled anaphylactoid purpura (Henoch-Schönlein disease) in man. Fungal infection was ruled out by special stains which failed to show...
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...
Woolcock JB.Using the long chain test, and in some cases the bactericidal test, to measure antibody, the development of the immune response in horses to Str. equi has been followed. Long chain indices in excess of 5.0, accompanied by strong bactericidal capacity, were recorded in serums after the full 3-dose immunisation course with a commercial vaccine. The full course elicited the most satisfactory antibody titres declined within the 12 month post-vaccination period, thus providing support for the recommendation that yearly booster doses should be administered. The immune response in horses during 2 str...
Woolcock JB.An atypical variety of Streptococcus equi is described. It was shown to be deficient in capsular material, to be very virulent for mice and to possess a cell-wall protein similar to the M-like protein of classical Str equi. Antiserum prepared against classical Str equi effectively opsonised the atypical strains, and induced the formation of long chains by these atypical strains. It is possible that this variant of Str equi can be used to overcome many of the current problems associated with the manufacture and use of strangles vaccines.
Woolcock JB.Equine tonsillar tissue and the draining regional lymph nodes, as well as deep nasal swabs were examined bacteriologically. Group C streptococci, predominantly Streptococcus zooepidemicus, were shown to be present in all tissues. The most frequent site for isolation was the tonsil. Streptococcus equi was not located in any of the tissues sampled.
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...
Ensink JM, Klein WR, Barneveld A, Vulto AG, Van Miert AS, Tukker JJ.The distribution of penicillins into a tissue chamber implanted subcutaneously in ponies was studied. Ampicillin sodium (equivalent to 15 mg/kg ampicillin) was administered intravenously. Pivampicillin, a prodrug of ampicillin, was administered by nasogastric tube to fed ponies at a dose of 19.9 mg/kg (equivalent to 15 mg/kg ampicillin). Procaine penicillin G was administered intramuscularly at a dose of 12 mg/kg (equivalent to 12000 IU/kg). Six ponies were used for each medication. Antibiotic concentrations in plasma and tissue chamber fluid (TCF) were measured for 24 h after administration. ...
