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1.
The prevalence of Streptococcus equi serovar equi (S.equi) in nasal discharge and pus samples from sub‐mandibular lymph nodes in mules at the Remount Depot, Sargodha was examined and total serum proteins, serum albumin, serum globulin and fibrinogen measured. A total of 250 nasal swabs and pus samples were collected from mules and examined microbiologically: 99 (39.6%) were positive for S. equi. A higher occurrence of S. equi was recorded in foals as compared to adults. The concentrations of total serum protein, serum globulin and fibrinogen were significantly increased (P<0.05), while the concentration of serum albumin significantly decreased (P<0.05) in strangles‐affected mules. It was concluded that increased total serum proteins, serum globulin and fibrinogen along with decreased serum albumin were important indicators of infection by S. equi in mules.  相似文献   

2.
The objective of this study was to use a new subtyping technique to determine the identity of five Streptococcus equi isolates from four outbreaks of strangles in Colorado during 2005−2006. All five of the isolates from the four strangles outbreaks in Colorado contained SeM allele 28. This SeM allele is typical of American isolates of S. equi and has previously been linked with strangles outbreaks in Minnesota in 1994 and Kentucky in 1995. Use of the new S. equi strain subtyping method allowed for characterization of recent S. equi isolates associated with outbreaks of strangles in Colorado. To our knowledge, this is the first report of typing of more recent isolates from North America. This approach, however, has been used in situations in the United Kingdom to differentiate the vaccine strain of S. equi from that of the wild type of the bacteria.  相似文献   

3.
Rhodococcus equi is a significant cause of pneumonia, resulting in disease and sometimes death of foals. It is believed that infection occurs by inhalation of dust contaminated with virulent R equi. Although association between the airborne concentration of virulent R equi and the incidence of foal pneumonia at breeding farms has been documented, studies at the level of individual foals have not been reported. Thus, the objective of this study was to determine whether the magnitude of airborne virulent R equi was significantly associated with risk of R equi pneumonia for individual foals. The concentration of virulent R equi was significantly (P < .001) greater in stalls than paddocks among samples collected from 47 foals at a breeding farm in central Kentucky. The presence of airborne virulent R equi in stalls was significantly (P = .045) more likely at 7 days of age for foals subsequently found to be affected by rhodococcal pneumonia. Additionally, airborne concentrations of virulent R equi in stalls were significantly greater at 7 and 14 days of age than at birth. Presence of the mare and foal at the time of sampling was significantly (P < .001) associated with increased airborne concentrations of virulent R equi in stalls. These findings suggest that environments containing airborne virulent R equi during the first week of life may influence the risk of subsequent disease for a foal.  相似文献   

4.
Streptococcus equi subspecies (ssp.) equi infection (strangles) remains one of the most frequently diagnosed and costly infectious diseases of horses. Large breeding herds, where a disease outbreak competes for personnel and financial resources needed for foaling management, present a special challenge for equine practitioners. A 15‐month outbreak involving 62 clinical cases of strangles occurred on a large Standardbred breeding farm (average population of 1400 horses). Sixteen asymptomatic horses were found to be PCR (polymerase chain reaction)‐positive for S. equi ssp. equi. During the outbreak, serological samples from 48 clinically normal horses were found to be seropositive for S. equi ssp. equi, confirming herd‐wide exposure. After several clinical cases of strangles had been diagnosed, an intranasal S. equi ssp. equi vaccine was administered to clinically normal horses (n = 558) considered to be at risk of exposure. Strangles complications included 7 fatalities (none in vaccinated horses) and 6 cases of purpura haemorrhagica (4 in vaccinated horses). Midway through the outbreak, injectable, sustained release ceftiofur crystalline free acid (CCFA), given as an initial dose followed by a second dose 4 days later, was used exclusively for systemic antimicrobial treatment of clinically affected and PCR‐positive horses. This antimicrobial regimen coincided with a reduction in disease incidence and eventual resolution of the outbreak. Two horses with persistent guttural pouch infection were endoscopically confirmed as carrier horses. The herd history demonstrated that a strangles outbreak will often result in asymptomatic carrier horses and that identification and treatment of these horses are necessary to eliminate long‐term sources of infection. Ceftiofur crystalline free acid was found to be a suitable antimicrobial due to its activity against S. equi ssp. equi and the efficiencies associated with twice parenteral dosing during a 10‐day treatment period. Occurrence of purpura in 4 vaccinated horses suggests that vaccination should be reserved for healthy seronegative horses and avoided during an active outbreak.  相似文献   

5.
A live attenuated vaccine against Streptococcus equi was administered submucosally in the upper lip to 224 pregnant and healthy mares to evaluate its safety. After a primary immunisation the mares were inoculated every 3 months until foaling. As control group, 206 mares of the same breeding farm were administered the solvent of the vaccine submucosally. None of the 430 mares presented any clinical evidence of strangles and neither local nor systemic reactions to vaccination were noticed. There was no association between abortion and vaccination. Furthermore no case of S. equi infection was revealed at post mortem examinations of aborted foals.  相似文献   

6.
Streptococcus equi ssp. equi infection in the horse, or strangles, commonly results in abscessation of the submandibular, submaxillary or retropharyngeal lymph nodes. Although this classical presentation of strangles is associated with a low mortality rate, complications and sequlae may worsen the prognosis and increase mortality rates. This article reviews sequelae and complictions of S. equi ssp. equi infection in the horse, including guttural pouch empyema, bastard strangles and immune mediated diseases such as purpura haemorrhagica, myopathies and myocarditis.  相似文献   

7.
Episodes of frenzy lasting approximately 30 minutes were observed among horses confined to enclosures surfaced with sand or soil. The probability of sighting these episodes increased by a factor of three when within 24 hours there was 0.2mm or more of rain, a maximum air temperature between 16.7 – 26.6°and a soil temperature of 16.3 – 23.9°C at 30 cm. High egg counts of Strongyloides westeri appeared in faeces four to five days later and persisted for several days.

Rhodococcus equi was recovered from all soil samples, and from the faeces of 76% of mares and 82% of foals. The youngest foal was five days old when the organism was isolated from rectal faeces. In contrast to the majority of reports, the lesions of R. equi in the foals were confined to limbs and peripheral lymph nodes.

It is proposed that the percutaneous invasion of these foals by third stage larvae of S. westeri facilitated invasion of R. equi, and ubiquitous saprophytic opportunist pathogen.(2)  相似文献   

8.
The aim of this study was to evaluate the usefulness of the previously identified B‐cell epitope TSLNLQKDEPNGRASDTAGQ of the VapA protein of Rhodococcus equi and its association with R. equi pneumonia. A modified peptide designated PN11‐14 corresponding to the epitope was recognized by all sera from experimentally infected foals with virulent R. equi ATCC103+ containing the virulence plasmid but not by its plasmid‐cured derivative ATCC103? strain. Marked levels of VapA‐specific immunoglobulin (Ig)G were detected in all sera from the ATCC103+ infected foals at 2 weeks after the infection. One control animal had high titres as determined by the peptide enzyme‐linked immunosorbent assay (ELISA), indicating the ELISA may not absolutely differentiate between foals with R. equi pneumonia and healthy exposed foals in farms where the prevalence of disease is high. However, numbers of animals used were small. Further evaluation of the peptide ELISA with field samples is necessary to determine whether the assay is diagnostically useful. This study showed that levels of passive transfer of maternal IgG antibodies to the epitope in newborn foals could be measured. Interestingly, the maternally derived antibodies were found to significantly (P < 0.05 by Student's t‐test) decline 2 weeks after birth. Seroconversion against naturally occurring VapA expressing R. equi could be detected in some foals at 4 weeks of age. Antibodies to the epitope peaked and were significantly (P < 0.05) greater in foals aged between 6 and 8 weeks. These results indicated that the peptide ELISA could be used to monitor anti‐VapA antibodies in foals, particularly those at the age of 4–6 weeks. It is possible that the ELISA may be of some use as a diagnostic test on farms where R. equi is non‐endemic. Further studies using large number of field samples are needed to verify this assumption.  相似文献   

9.
Four month-old foals were infected orally with 75 mL of a suspension of 5.0 × 108 Corynebacterium equi per mL. Two foals were killed after ten days and had scanty number of C. equi in the caeco-colic lymph nodes. No C. equi were recovered from the other two foals, killed 20 days after infection. No gross pathological change was detected in these four foals, although mild microscopic lesions were seen in the ileum of one foal. Results of lymphocyte blastogenesis using peripheral blood lymphocytes and C. equi antigens showed, however, that lymphocytes became sensitized to C. equi following this challenge.

In a second experiment four month-old foals were given orally the same dose of organisms but on five consecutive days. Two foals were killed ten days after infection and showed mild histological changes in the large bowel mucosa and C. equi could be recovered from all intestinal lymph nodes cultured. In one of these foals moderate numbers of C. equi were present in the bronchial lymph node. Of the other two foals, one died after 22 days with severe ulcerative enterocolitis and intestinal lymphadenitis. Only one small pulmonary abscess was detected despite large numbers of C. equi in the lungs. The other foal developed similar intestinal changes and was euthanized 25 days after infection. No C. equi were detected in the lungs or bronchial lymph node. Lymphocyte blastogenesis in these animals showed a rapid rise in response to C. equi antigens.

These studies suggest that C. equi pneumonia in foals does not always arise from an intestinal infection, that minor intestinal infection causes a cellular immune response and that massive exposure of the bowel over a sustained period is necessary to induce intestinal lesions.

  相似文献   

10.
Rhodococcus equi is an important cause of pulmonary disease in foals often related to economic losses and death. A study was performed on a Thoroughbred farm (Buenos Aires Province, Argentina) where this disease was enzootic causing 1–2% of foal deaths every year. One hundred foals were monitored by thoracic ultrasonography at ages 1–5 months to detect pulmonary lesions in order to initiate an early treatment. This strategy allowed reducing the number of foal deaths almost totally. In our experience, thoracic ultrasonography was proved to be very efficient in detection of early cases of pneumonia on a farm with high density of horses and intensive management.  相似文献   

11.
Objective – To describe the clinical presentation, case management, and outcome in 2 foals with Rhodococcus equi infection associated with presumptive severe immune‐mediated hemolytic anemia. Series Summary – Two foals diagnosed with R. equi pneumonia on the basis of tracheal wash cultures, thoracic radiographs, and thoracic ultrasonography were concurrently diagnosed with hemolytic anemia. Both foals required whole blood transfusions, and were treated with the antimicrobial combination of rifampin and a macrolide (eg, clarithromycin, erythromycin, or azithromycin). Dexamethasone was used to prevent further hemolysis in both foals, and to treat acute lung injury/acute respiratory distress syndrome in 1 of the foals. Both foals survived, and required prolonged antimicrobial therapy. New or Unique Information Provided – Although extra‐pulmonary disorders are commonly diagnosed in foals infected with R. equi, hemolytic anemia is rarely described. Dexamethasone is considered the treatment of choice for immune‐mediated hemolytic anemia, but may be contra‐indicated in foals with severe bacterial infections. In these foals, a relatively low dose and short duration of dexamethasone was utilized in an attempt to minimize immune suppression, although early discontinuation in 1 foal precipitated a second hemolytic crisis.  相似文献   

12.
Reasons for performing study: Strangles is the most commonly diagnosed and important infectious disease of horses worldwide. Very little is known about the temporo‐spatial and molecular epidemiology of strangles. The disease is not notifiable in the UK and there are few published data on the geographical locations of outbreaks. Objective: To investigate whether typing of a surface protein (SeM) of Streptococcus equi ssp. equi (S. equi), the causative agent of strangles, is a useful epidemiological tool. Methods: The variable region of the SeM gene was amplified from 145 isolates of S. equi by PCR and sequenced. Different SeM gene alleles were assigned based on the SeM database, grouped into phylogenetic clusters using split decomposition analysis and plotted against the submitting veterinary practices. Results: In this study 21 S. equi SeM alleles were found, including 9 previously unidentified alleles and representing 4 phylogenetic groups. S. equi containing SeM alleles 9 and 7 were the most commonly isolated and there was a high number of low frequency alleles. The occurrence of an outbreak cluster in the north‐west of the UK is also reported. Conclusions: Strangles outbreaks can be differentiated on the basis of their SeM allele sequences. The data provide further evidence of SeM mutation leading to the emergence of novel, but related SeM alleles that are geographically linked. Sequencing of the SeM gene is a useful tool for the elucidation of strangles epidemiology at a regional and a national level. Potential relevance: This technique may allow differentiation or linkage of strangles outbreaks and as such may be an effective tool for local as well as national and international disease surveillance.  相似文献   

13.
CASE DESCRIPTION: A 4-month-old American Paint Horse colt was evaluated because of acute onset of ataxia, left-sided head tilt, and fever and a recently noticed heart murmur. Upper respiratory tract infection caused by Streptococcus equi subsp equi had been diagnosed at 3 months of age. CLINICAL FINDINGS: Hematologic abnormalities included leukocytosis, mature neutrophilia, monocytosis, and mild anemia. Analysis of a CSF sample revealed high total protein concentration and total nucleated cell count; nucleated cells consisted mainly of degenerate neutrophils. Results of a real-time PCR assay were positive for S equi subsp equi, and a diagnosis of S equi subsp equi meningoencephalomyelitis was made. TREATMENT AND OUTCOME: Treatment included administration of potassium penicillin and fluids, but the foal developed uroperitoneum and was subsequently euthanized. Postmortem examination revealed meningoencephalomyelitis, and S equi subsp equi was cultured from a brain aspirate. Additional findings included suppurative cystitis with rupture and neutrophilic myocarditis. CLINICAL RELEVANCE: Findings suggest that S equi subsp equi meningoencephalomyelitis should be considered in the differential diagnosis for foals with neurologic signs that have a history of strangles or exposure to affected horses.  相似文献   

14.
A relative immunodeficiency of young foals is considered to account for the increased susceptibility of foals to infectious diseases, including pneumonia caused by Rhodococcus equi. In this report, peripheral blood mononuclear cells (PBMCs) from healthy foals at 14 and 56 days of age, or from their dams, were incubated with three stimulatory and one nonstimulatory (control) synthetic cytosine-phosphate-guanosine oligodeoxynucleotides (CpG-ODNs), and mRNA expression of tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL) -6, IL-8, IL12-p35, and IL-12p40 were determined. Results indicated that synthetic CpG-ODNs can induce strong, rapid cytokine responses in healthy foals and adult horses. B-class CpG-ODNs 2135 and 2142 induced greater messenger RNA (mRNA) expression of IFN-γ, IL-6, and IL-12p40 than the C-class CpG-ODN 2395 in foal PBMCs. In foals, B-class CpG-ODNs induced IFN-γ, IL-6, and IL-12P40 mRNA expression that was similar to or higher in magnitude than that observed in adult horses. These observations indicate that CpG-ODNs might be useful as immunomodulators or as potential adjuvants for vaccines to aid in preventing R. equi pneumonia and other bacterial diseases of foals.  相似文献   

15.
This case report describes the treatment and outcome of a 3.5-month-old lame foal, with a history of pneumonia associated with Rhodococcus equi. Clinical examination identified osteomyelitis of the scapulohumeral joint. The unusual location of the Rhodococcus equi osteomyelitis unresponsive to prevention and adequate treatment led to euthanasia of the patient. Post-mortem findings confirmed bronchopneumonia due to Rhodococcus equi as well as the osteomyelitis of the scapulohumeral joint. This case highlights that Rhodococcus equi should be considered as a pathogen in extrapulmonary locations such as septic arthritis and osteomyelitis in foals with history of bronchopneumonia. Early and aggressive treatment should be considered.  相似文献   

16.
Pneumonia caused by Rhodococcus equi is one of the most important causes of disease and death in foals. R. equi can also be cultured from a large variety of extrapulmonary sites of infection. In the absence of an effective vaccine, ultrasonographic screening for early detection of pulmonary lesions has become routine practice at many farms endemic for pneumonia caused by R. equi. Consequently, the most frequently recognised form of R. equi infection at such farms is a subclinical form in which foals develop sonographic evidence of peripheral pulmonary consolidation or abscessation without necessarily manifesting clinical signs. Evidence exists that not all foals with ultrasonographic lesions will progress to develop clinical signs, and treating a large proportion of foals based on subclinical ultrasonographic findings has been linked to emergence of macrolide‐ and rifampin‐resistant R. equi at a horse farm. Selectively treating only those foals with larger lesion scores and monitoring foals with daily physical inspections and weekly thoracic ultrasonography offers an approach that could decrease antimicrobial drug use without significantly increasing mortality. Current evidence continues to support the combination of rifampin with a macrolide (azithromycin, clarithromycin or erythromycin) for treating clinical infections caused by R. equi despite recently described pharmacological interactions between these drugs. When infection with a macrolide‐resistant isolate is confirmed, limited effective alternatives exist.  相似文献   

17.
A total of 227 field samples from naturally exposed foals aged between 3 weeks and 6 months were used in an evaluation of a peptide‐based enzyme‐linked immunosorbent assay (ELISA) for diagnosis of Rhodococcus equi infection. A biotinylated peptide derived from the virulence‐associated protein A (VapA) of R. equi, a horse pathogen, was synthesized and designated as PN11‐14. The peptide corresponds to the N‐terminal B‐cell epitope TSLNLQKDEPNGRASDTAGQ of the VapA protein. Based upon a serum immunoglobulin (Ig)G titre of 512 as a positive cut‐off value for the R. equi infection, the ELISA provided the overall sensitivity of 47.62%, specificity of 69.67% and an accuracy of 59.47% with a positive predictive value of 57.47% for true R. equi pneumonia. The assay was improved by detecting VapA‐specific IgGb antibodies against N‐terminal B‐cell epitope of the VapA protein rather than IgG antibodies. The VapA‐IgGb ELISA showed the overall sensitivity of 70.47%, specificity of 72.13% and accuracy of 71.36% with a positive predictive value of 68.52%. Diagnosis of R. equi disease in 6‐week‐old foals showed that the VapA‐IgGb ELISA provided an increasing trend (P = 0.0572) in sensitivity of 82.4% in comparison with the VapA‐IgG ELISA which showed the sensitivity of 58.8%. However, differences in specificity of both tests were statistically insignificant (P = 0.357) as analysed by the McNemar test. These results indicated that detection of VapA‐specific IgGb antibodies may be a better predictor of R. equi disease in foals.  相似文献   

18.
Reasons for performing the study: Disease caused by Rhodococcus equi is a significant burden to the horse breeding industry worldwide. Early detection of rhodococcal pneumonia, albeit important to minimise treatment costs, is difficult because of the insidious nature of the disease and the lack of definitive diagnostic tests. Objectives: To investigate air sampling from the breathing zone of neonatal foals as a predictor of subsequent rhodococcal pneumonia. Methods: Air samples were collected from the breathing zone of 53 neonatal foals (age ≤10 days) and again at the time of routine ultrasonographic screening for R. equi pneumonia (age 1–2 months). Results: Pneumonia was diagnosed ultrasonographically in 23% of foals. Virulent R. equi was detected in air from the breathing zone of 19% of neonatal foals and 45% of foals at age 1–2 months. There was no association between virulent R. equi in the breathing zone of foals and the subsequent ultrasonographic diagnosis of rhodococcal pneumonia. The median concentration of virulent R. equi in the breathing zone of both neonates (0 [range 0–4] colony‐forming units [cfu]/250 l) and older foals (0 [range 0–3] cfu/250 l) was not significantly different from that in background air samples (0 [range 0–6] cfu/250 l). There was no difference in the concentration of virulent R. equi in the breathing zone of older foals that were diagnosed with rhodococcal pneumonia or clinically normal foals. Conclusion: Detection of virulent R. equi in air from the breathing zone was not a positive predictor of rhodococcal pneumonia in foals up to age ≤2 months. Potential relevance: Selective culture of air samples from the breathing zone of young foals is not better at diagnosing rhodococcal pneumonia than early ultrasonographic screening. However, culture of air samples from the breathing zone of older foals remains a useful herd‐based epidemiological tool.  相似文献   

19.
Reasons for performing the study: Chronic and acute alterations in maternal nutrient intake during pregnancy alter pancreatic and hypothalamo‐pituitary‐adrenal (HPA) axis function in the offspring, before and after birth. Little is known about these effects. Objective: To determine whether maternal nutrient restriction caused by natural infection with Streptococcus equi altered endocrine function in neonatal foals born from mares fed a maintenance or high plane of nutrition throughout pregnancy. Methods: Ten primiparous mares received either a diet to maintain moderate body condition score (Moderate, n = 5) or a near ad libitum feeding regime to maintain a high body condition score (High, n = 5) throughout pregnancy. All mares inadvertently became infected with Streptococcus equi in mid gestation and lost approximately 10% body mass. Results: Maternal insulin and glucose concentrations decreased (P<0.05) during, and one month following, the weight loss period. High mares weighed more (P<0.05) at parturition than Moderate mares; all foals were healthy. Gestational age, foal bodyweights, placental and clinical parameters after birth were no different between the 2 groups. Foal plasma cortisol and glucose responses to exogenous adrenocorticotrophic hormone and insulin, respectively, were similar for both groups. Insulin concentrations during glucose tolerance test were significantly higher (P<0.05) in foals from Moderate than High mares and compared with foals studied previously from healthy, well‐fed mares, suggesting that the β cell sensitivity to glucose was enhanced in Moderate. Conclusion: Acute nutrient restriction in mid gestation caused by maternal illness and inappetence, superimposed on a maintenance feed intake throughout pregnancy, enhanced insulin secretion to glucose in foals. Nutritional programming of pancreatic β cells, but not the HPA axis, appeared to depend on the level of nutrition before and after the weight loss period. Potential relevance: Disturbances in neonatal pancreatic β cell function programmed during pregnancy may predispose foals to metabolic problems in later life.  相似文献   

20.
This report describes the diagnosis and successful treatment of multiple extrapulmonary sequelae of Rhodococcus equi (R. equi) pneumonia in a 3‐month‐old filly. Bilateral uveitis and hyphaema, haemolytic anaemia and polysynovitis developed in this foal and were likely due to immune‐mediated mechanisms. The challenges associated with diagnosis and treatments of these extrapulmonary disorders are discussed. The filly was treated initially with clarithromycin and rifampin; however, a blood transfusion and immunosuppressive therapy with dexamethasone were required due to progressive haemolysis and for treatment of uveitis and polysynovitis. Bilateral hyphaema was successfully treated with intracameral injections of a recombinant tissue plasminogen activator. The development of antimicrobial resistance in R. equi was an additional challenge encountered in the management of this case and emphasises the importance of culture and in vitro antimicrobial susceptibility testing of isolates from foals with R. equi pneumonia. Extrapulmonary disorders associated with R. equi pneumonia are likely underdiagnosed and associated with a poor prognosis. This case highlights the importance of thorough and ongoing diagnostic assessment of foals with R. equi pneumonia and demonstrates that a successful outcome can be achieved with appropriate and directed treatment.  相似文献   

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