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Successful medical therapy of Rhodococcus equi pneumonia in a patient with HIV infection.

A 34-year-old HIV-infected man was successfully treated with antimicrobial therapy alone for Rhodococcus equi pneumonia and has survived longer than six months. In the current literature, only two of seven HIV-infected patients so treated have survived as long as six months. Based on our experience and the available literature, it seems reasonable to treat HIV-infected patients with R equi pneumonia who do not require surgical intervention with prolonged intravenous therapy followed by long-term oral therapy with at least two effective antibiotics. The optimal choice and duration of antibiotic therapy need to be determined.

AIDS-Related Opportunistic Infections↗

Protection of foals against experimental Rhodococcus equi pneumonia by oral immunization.

Two groups of three one to three week old foals were immunized orally on four occasions over five weeks with two strains of Rhodococcus equi, a clinical isolate from a pneumonic foal and a laboratory passaged Congo red negative variant of this strain. Three nonimmunized foals of similar age acted as controls. Three weeks after the last immunization, all foals were challenged on five occasions over seven days by aerosol infection with about 10(10) of the pneumonic foal isolate on each occasion. Control foals became seriously ill and were euthanized. Immunization with either strain protected foals equally against the challenge, and resulted in rapid lung clearance. Oral immunization can thus protect foals against severe challenge with R. equi. The proteins associated with Congo red colony staining appear not to be involved in protective immunity.

Actinomycetales Infections↗

Rhodococcus equi foal pneumonia: protective effects of immune plasma in experimentally infected foals.

The immunoprophylactic capacity of specific immune plasma was evaluated in pony foals infected experimentally with Rhodococcus equi. Immune plasma, produced by repeated parenteral administration of viable R. equi to adult horses, was harvested and frozen. Group I (six control foals) and Group II (six principal foals) received lactated Ringers solution and immune plasma respectively at three and five days of age. R. equi were aerosolised into a caudal lung lobe of all foals at seven days of age. Clinical signs, haematological alterations, immune responses, thoracic radiographs and technetium99m pulmonary perfusion scans were monitored. All foals were destroyed and complete post mortem examinations performed. All foals developed pneumonia as evidenced by clinical, radiographic and perfusion alterations, but the survival rate of principal foals was significantly (P less than 0.01) greater than that of control foals. Five control foals developed terminal disease, whereas all principal foals recovered. There was no significant (P greater than 0.05) difference in temperature response, or peripheral blood leucocyte, neutrophil or fibrinogen concentrations between groups. ELISA values for R. equi antibody were significantly (P less than 0.001) greater in principal foals following treatment, but there was no significant (P greater than 0.05) difference in IgG or IgM concentrations between groups. Results of the haemolysis inhibition assay indicated that equi factor neutralising antibodies were transferred by immune plasma to the principal foals. Post mortem examinations of five control foals destroyed at approximately three weeks post infection because of terminal disease, revealed severe pyogranulomatous pneumonia. One control and all principal foals were either free of lesions or had resolving lesions and/or minimal scar formation at three months post infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomycetales Infections↗

Comparison of nucleic acid amplification, serology, and microbiologic culture for diagnosis of Rhodococcus equi pneumonia in foals.

Recently, a technique was described for amplification of Rhodococcus equi-specific chromosomal and vapA DNA from blood and tracheal wash fluids. It was hypothesized that this technique would be more sensitive than standard culture techniques or serology for diagnosis of R. equi pneumonia in foals. Tracheal wash fluid, nasal swabs, whole blood samples, and serum samples from 56 foals with pneumonia were analyzed. Final clinical diagnosis was determined by the attending clinician on the basis of final interpretation of all available information about each foal, including clinical presentation, diagnostic test results, response to therapy, and outcome. Clinical diagnosis was used as a final reference standard for calculation of sensitivity, specificity, and predictive values for PCR, serology using an agar gel immunodiffusion test, and tracheal wash fluid culture. PCR of tracheal wash fluid using primers that recognized the vapA virulence plasmid of R. equi had a diagnostic sensitivity of 100% and specificity of 90.6%. Sensitivity and specificity were 57.1 and 93.8%, respectively, for standard microbiologic culture of tracheal wash fluid and 62.5 and 75.9%, respectively, for serology. PCR of tracheal wash fluid is more sensitive and specific for diagnosis of R. equi pneumonia than are other available diagnostic tests.

Actinomycetales Infections↗

[Rhodococcus equi infection in a goat].

Enterotoxaemia caused by Clostridium perfringens was diagnosed in a goat affected with severe enteritis which was found to be present at autopsy. Lesions bearing a resemblance to tuberculosis, caused by a Rhodococcus equi infection, were observed in the liver and lungs. This bacterium is constantly isolated from pulmonary abscesses in foals affected with pyemia. Similar cases of infection in goats were previously reported in the literature.

Abscess↗

Septicemia, atrial fibrillation, cardiomegaly, left atrial mass, and Rhodococcus equi septic osteoarthritis in a foal.

A foal with vegetative bacterial endocarditis affecting the wall of the left atrium was treated successfully with cefotaxime, erythromycin, and rifampin. Bacterial isolates included Escherichia coli from blood and Rhodococcus equi from a P-type osteomyelitic lesion of the left third metatarsal bone and from synovial fluid from the left metatarsophalangeal joint. Cardiac complications included cardiomegaly and atrial fibrillation, which responded to treatment with digoxin and quinidine sulfate. Cardiac function was considered normal 18 months after treatment. Bacteriologic cure of osteoarthritis was achieved by use of surgical debridement, lavage, and local and systemic antimicrobial treatment; however, lameness developed 18 months after treatment when training for flat racing was begun. Radiography revealed chronic degenerative joint disease.

Actinomycetales Infections↗

The interaction of Rhodococcus equi and foal neutrophils in vitro.

Polymorphonuclear neutrophil leukocytes (PMNL) from 8 healthy foals (2-14 weeks of age) and 2 foals with bacterial pneumonia were separated from whole blood using a 2 step Percoll gradient. Purified PMNL were tested for bactericidal function against Rhodococcus equi and Staphylococcus aureus in the presence of normal horse serum. The percentage uptake after a 15-min pre-incubation of PMNL and bacteria was also calculated. Ultrastructural examination of the interaction of R. equi and normal foal PMNL was performed after 15 min incubation. Results indicated that foal PMNL effectively phagocytose and destroy R. equi and S. aureus in the presence of normal horse serum. The mean percent uptake for R. equi was 99.3 +/- 0.4% and for S. aureus 99.9 +/- 0.1%. Further, 97.8 +/- 0.1% ingested R. equi and 98.4 +/- 0.1% ingested S. aureus were destroyed in the 15-min incubation period. Over the 3-h incubation, 91.9% of remaining R. equi were killed, but only 49.2 +/- 31.9% of S. aureus (P less than 0.01). Total bactericidal effect of foal PMNL, however, was 99.3 +/- 0.4% against R. equi and 99.9 +/- 0.1% against S. aureus. The percentage uptake and total bactericidal efficacy of neutrophils from sick foals was greater than 95%. Ultrastructural examination of the PMNL-R. equi interaction after 15 min incubation revealed phagocytosis of the bacteria and morphologic changes consistent with neutrophil degranulation. This study suggests that a defect in PMNL bactericidal capability is not likely to be a contributing factor in the pathogenesis of R. equi pneumonia in foals.

Actinomycetales Infections↗

[Rhodococcus equi pneumonia in a patient with acquired immunodeficiency syndrome].

A male patient of 33 years of age with AIDS developed pneumonia with abscess formation and a slow clinical course. The sputum, bronchoalveolar lavage and blood cultures yielded a Gram-positive, partially acid-alcohol resistant bacillus which was identified as Rhodococcus equi. This organism has been uncommonly implicated in pneumonia in patients with immunodeficiency, particularly with neoplasia and severe cell immunity deficiency. It has been very rarely reported in patients with AIDS. To our knowledge, this is the first reported case in Spain.

Acquired Immunodeficiency Syndrome↗

Cellulitis and subcutaneous abscesses caused by Rhodococcus equi infection in a foal.

Cellulitis and subcutaneous abscess formation was diagnosed in a 3-month-old Thoroughbred filly. Clinical signs consisted of a large ulcerated plaque, with satellite pustules on the medial aspect of the right hock and subcutaneous abscesses in the right inguinal and mammary gland areas. Laboratory analysis revealed mature neutrophilia. Rhodococcus equi was isolated from the cellulitis and the subcutaneous abscess. Oral administration of erythromycin and rifampin for 35 days resulted in a clinical cure.

Abscess↗

The association between weather, frenzied behaviour, percutaneous invasion by Strongyloides westeri larvae and Rhodococcus equi disease in foals.

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 degrees C and a soil temperature of 16.3 - 23.9 degrees 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.

Journal Article↗

Infection with Rhodococcus equi in a patient with sarcoidosis treated with corticosteroids.

A 51-year-old female farmer was diagnosed as having sarcoidosis. During 4 years of observation, slow radiological progression was observed. Cough then developed, necessitating treatment with corticosteroids. After 28 months of continuous treatment with prednisolone in low doses (5-7.5 mg daily), she suffered fever episodes, recurrent haemoptyses, general malaise and loss of weight. A chest roentgenogram showed a left upper lobe infiltrate, which progressed and finally cavitated, and rib destruction. Despite efforts, including a thoracotomy, 22 months passed before a diagnosis could be made. Blood and sputum cultures and cultures from the destroyed rib showed growth of Rhodococcus equi, a common soil organism which can cause infections in foals and other animals. Treatment with rifampicin and erythromycin was successful. R. equi has been reported to cause infection in patients with neoplastic disease and/or immunosuppression, but the disease might be more common than is suggested by the sparse case reports in the literature, owing to lack of familiarity with the organism, which will tend to be overlooked as a contaminant.

Actinomycetales Infections↗

Opportunistic lung infection caused by Rhodococcus (Corynebacterium) equi.

Rhodococcus (formerly Corynebacterium) equi, a common animal pathogen, can cause a slowly evolving pneumonia in humans, particularly immunocompromised people. The authors describe two patients; one with acquired immunodeficiency syndrome. On chest radiographs, R. equi produces chronic, localized pulmonary opacities that can cavitate. The main differential diagnoses are tuberculosis and fungal infection.

Acquired Immunodeficiency Syndrome↗

Rhodococcus equi infection in non-HIV-infected patients. Two case reports and review.

OBJECTIVE: To review two recent cases in HIV-negative subjects in the light of literature reports (52 patients without HIV infection till 1994). METHODS: Epidemiology (animal contacts, risk factors, year, country), clinical presentation, diagnostic methods (X-ray, tomography, microbiological techniques), therapeutic approach (antibiotics, surgery) and outcome were evaluated on the basis of clinical literature reports. RESULTS: Tumors constituted an important predisposing factor and less frequently hepatobiliary pathology, rheumatologic diseases, iatrogenic causes, psychiatric pathology and trauma. Exposure to animals was reported by 55% of the patients. Pneumonia and pleurisy, without preferential localization, were detected in 50% of the patients. Etiologic diagnosis was usually obtained after an invasive collection. Combined medical therapy and surgery were required by 27.8% of the patients, and 16.7% of the patients died. CONCLUSIONS: In recent years the number of Rhodococcus equi cases has been rising also in HIV-negative patients. The infection is ubiquitous. Accurate diagnosis and the prompt selection of the most appropriate therapy depend on close cooperation between clinicians and microbiologists.

Journal Article↗

Evaluation of white blood cell concentration, plasma fibrinogen concentration, and an agar gel immunodiffusion test for early identification of foals with Rhodococcus equi pneumonia.

OBJECTIVE: To evaluate WBC concentration, plasma fibrinogen concentration, and an agar gel immunodiffusion (AGID) test for early identification of Rhodococcus equi-infected foals. DESIGN: Prospective study. ANIMALS: 162 foals from a farm with enzootic R equi infection. PROCEDURE: Blood samples were obtained from each foal at 4-week intervals for measurement of WBC and plasma fibrinogen concentrations and at 2-week intervals for detection of anti-R equi antibody by an AGID assay. Diagnostic performance of WBC and fibrinogen concentrations was assessed by use of receiver operating characteristic curve analysis. For each assay, sensitivity, specificity, and predictive values were calculated at various cutoff points; bacteriologic culture of R equi from a tracheobronchial aspirate was used as the reference standard test. RESULTS: Diagnostic performance of WBC concentration was significantly higher than that of fibrinogen concentration. Sensitivity and specificity of measurement of WBC concentration at a cutoff of 13,000 cells/microL were 95.2 and 61.2%, respectively; at a cutoff of 15,000 cells/microL, sensitivity was 78.6% and specificity was 90.8%. When a positive test result was used as the cutoff, sensitivity of the AGID assay was 62.5% and specificity was 53.8%. CONCLUSION AND CLINICAL RELEVANCE: Monitoring WBC concentration is a useful approach for early detection of infected foals on farms with a high prevalence of R equi pneumonia. In contrast, serologic surveillance by use of an AGID assay is of little benefit for that purpose.

Actinomycetales Infections↗

Clostridium difficile associated with acute colitis in mares when their foals are treated with erythromycin and rifampicin for Rhodococcus equi pneumonia.

In Sweden, mares sometimes develop acute, often fatal, colitis when their foals are treated orally with erythromycin and rifampicin for Rhodococcus (R.) equi infection. Clostridium (C.) difficile, or its cytotoxin, was demonstrated in faecal samples from 5 of 11 (45%) mares with diarrhoea. By contrast C. difficile was not found in the faecal flora of 12 healthy mares with foals treated for R. equi infection or in 56 healthy mares with healthy untreated foals. No other enteric pathogen was isolated from any diarrhoeic mare. Of 7 investigated treated foals, 4 had a high (1651.0, 1468.3, 273.0 and 88.8 microg/g) faecal concentration of erythromycin. The dams of those 4 foals developed acute colitis, whereas the dams of 3 foals with a lower (26.3, 4.6 and 3.7 microg/g) faecal erythromycin concentration remained healthy, indicating that there might have been an accidental intake of erythromycin by mares. The foals treated with antibiotics were regarded as asymptomatic carriers and potential reservoirs, as C. difficile was found in 7 of 16 foals investigated, while 56 untreated foals proved negative. The isolated C. difficile strains proved resistant to both erythromycin (MIC>256 mg/l) and rifampicin (MIC>32 mg/l), a fact that may have favoured the growth of C. difficile in the foal intestine. All mares found positive for C. difficile were, or had recently been, hospitalised together with their foals, indicating that C. difficile may be a nosocomial infection, in horses. The results emphasise that routine testing for C. difficile and its cytotoxin is recommended when acute colitis occurs in mares when their foals are treated with erythromycin and rifampicin. Preventive measures in order to avoid accidental ingestion of erythromycin by mares from the treatment of their foals are suggested.

Actinomycetales Infections↗

[Long term survival after Rhodococcus equi pneumonia in a patient with human immunodeficiency virus infection in the era of highly active antiretroviral therapy: case report and review].

Before highly active antiretroviral therapy (HAART) has become available, antibiotic treatment was usually unable to eradicate Rhodococcus (R.) equi infection in HIV-infected patients, although some clinical improvement could be observed in most cases. There are limited data on the outcome of treatment of R. equi pneumonia in the HAART era. We report on a 52-year-old HIV-infected man who presented in poor general condition with an extensive lung cavitation lesion caused by R. equi. The patient recalled exposure to horses on several occasions. R. equi was cultured from the sputum and the isolate was sensitive to imipenem vancomycin, co-trimoxazole, erythromycin, azithromycin, ciprofloxacin and rifampicin. The CD4+ lymphocyte count was 5 cells/mm3 (0.9%) and his plasma HIV-1 RNA viral load was 101000 copies/mL. The patient was successfully treated with a combination of antibiotics that included azithromycin both as part of an initial and suppressive regimen together with antiretroviral treatment. Surgery was not needed and the patient had no relapse for more than five years after the diagnosis and for more than 3 years of suppressive therapy discontinuation. Our literature search revealed 27 patients treated for R. equi infection in the HAART era. However, details on antimicrobial treatment were given in only 3 cases. The optimal drug regimen and duration of treatment for R. equi pneumonia have not yet been established. Because drug resistance may occur during single agent therapy, it has been suggested that at least two antibiotics to which R. equi is susceptible be given. The recommended choices usually include imipenem, antipseudomonal aminoglycosides, erythromycin or azithromycin, vancomycin, rifampin, and levofloxacin. To our knowledge this is the first documented case of long term remission of R. equi pneumonia in an HIV-infected man treated with azithromycin as part of his antibiotic regimen and HAART.

AIDS-Related Opportunistic Infections↗