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PubMed1994

Rhodococcus equi pneumonia in an HIV-infected patient.

We report a case of a 46-year-old HIV-infected patient suffering Rhodococcus equi pneumonia and septicaemia. After the failure of an initial antibiotic treatment, the upper lobe of the right lung was resected due to a cavitating pneumonia. After that the patient stabilized for a period of 7 months by administration of a resistogram-adapted combination of tetracycline, erythromycin and clindamycin. Due to the patient's decision, antibiotic treatment was stopped when a cytomegalovirus retinitis was diagnosed. Six weeks later new pulmonary infiltrations were diagnosed and a Rhodococcus equi bacteraemia evolved. The patient died one year after the first diagnosis of the Rhodococcus equi infection. The present case suggests that the infection with Rhodococcus equi in patients with advanced HIV infection demands permanent antibiotic prophylaxis.

AIDS-Related Opportunistic Infections↗
PubMed2001

Purification and characterization of the enantioselective nitrile hydratase from Rhodococcus equi A4.

The nitrile hydratase from Rhodococcus equi A4 consisted of two kinds of subunits which slightly differed in molecular weight (both approximately 25 kDa) and showed a significant similarity in the N-terminal amino acid sequences to those of the nitrile hydratase from Rhodococcus sp. N-774. The enzyme preferentially hydrated the S-isomers of racemic 2-(2-, 4-methoxyphenyl)propionitrile, 2-(4-chlorophenyl)propionitrile and 2-(6-methoxynaphthyl)propionitrile (naproxennitrile) with E-values of 5-15. The enzyme functioned in the presence of 5-98% (v/v) of different hydrocarbons, alcohols or diisopropyl ether. The addition of 5% (v/v) of n-hexane, n-heptane, isooctane, n-hexadecane, pristane and methanol increased the E-value for the enzymatic hydration of 2-(6-methoxynaphthyl)propionitrile.

Amino Acid Sequence↗
PubMed1996

Immunohistochemical detection of virulence-associated antigens of Rhodococcus equi in pulmonary lesions of foals.

Rhodococcus equi was isolated from the lungs of six foals with bronchopneumonia. All isolates expressed 15-17-kd antigens by immunoblot analysis and contained a virulence-associated plasmid of 85 or 90 kb. Immunohistochemically, R. equi from all pulmonary lesions showed the expression of 15-17-kd antigens mainly in the phagocytic cells. The specific monoclonal antibody to 15-17-kd antigens of R. equi (MAb 10G5) may be an aid in the diagnosis of R. equi-induced pneumonia.

Actinomycetales Infections↗
PubMed1995

Cytokine modulation alters pulmonary clearance of Rhodococcus equi and development of granulomatous pneumonia.

Rhodococcus equi, a facultative intracellular bacterium, causes chronic, often fatal granulomatous pneumonia in young horses and in humans with AIDS. The inability of host alveolar macrophages to kill intracellular R. equi results in the development of granulomas and progressive loss of pulmonary parenchyma. Clearance of the organism from the lung requires functional CD4+ T cells. The purpose of this study was to identify the cytokine effector mechanisms that mediate clearance of R. equi from the lung. Mice were treated with monoclonal antibodies (MAbs) to either gamma interferon (IFN-gamma) or interleukin-4 (IL-4) to determine the role of endogenous production of these cytokines in pulmonary clearance of R. equi. Mice treated with an anti-IL-4 or isotype control MAb cleared R. equi by 21 days postinfection and expressed increased levels of IFN-gamma mRNA, as detected by transcriptional analysis of bronchial lymph node CD4+ T cells. In contrast, mice treated with the anti-IFN-gamma MAb failed to express detectable IFN-gamma mRNA, expressed increased levels of IL-4 mRNA, failed to clear pulmonary infection, and developed pulmonary granulomas with large numbers of eosinophils. The enhancement of IL-4 mRNA expression and a predominance of eosinophils in pulmonary lesions of anti-IFN-gamma-treated mice suggest that a nonprotective Th2 response in involved in disease pathogenesis. The association of increased bronchial lymph node CD4+ T-cell IFN-gamma mRNA expression with pulmonary clearance of R. equi suggests that a Th1 response is protective.

Actinomycetales Infections↗
PubMed1993

Virulence-associated plasmids in Rhodococcus equi.

Twenty-three strains of Rhodococcus equi from independent clinical cases were analyzed for the presence of virulence plasmid DNA. Of the clinical isolates, 19 contained an 85-kb plasmid and the remaining 4 contained a 90-kb plasmid. All of the isolates expressed 15- to 17-kDa antigens and were virulent in mice. Restriction enzyme and Southern blot analyses showed large regions of DNA homology between the 85- and 90-kb virulence plasmids. It was concluded tentatively that there are at least two virulence plasmids in R. equi and that they have a common origin.

AIDS-Related Opportunistic Infections↗
PubMed2005

Caprine vertebral osteomyelitis caused by Rhodococcus equi.

There have been reports of Rhodococcus equi infections in goats in Australia, America and India. In this study, R. equi was isolated from an inflamed vertebra in a Boer goat in South Africa. At autopsy, there was a purulent inflammatory reaction in the 1st cervical vertebra. Histopathologically, a neutrophilic infiltration was encountered in the bone. Aerobic culture of swabs collected from the abscesses yielded R. equi in pure culture that was identified on biochemical tests. R. equi has become important as the cause of an opportunistic infection in people suffering from HIV.

Actinomycetales Infections↗
PubMed1992

Therapy of Rhodococcus equi disseminated infections in nude mice.

Rhodococcus equi is a facultative, intracellular, gram-positive coccobacillus increasingly reported as an opportunistic pathogen in human immunodeficiency virus-positive patients. However, the optimal drug regimen for treating R. equi pulmonary or systemic infections is not yet known. Therefore, a model of intravenously infected nude mice with disseminated infection was created to study the efficacy of antibiotics alone or in combination as determined by the reduction of bacterial CFU per gram in the lungs and spleen after 4 and 11 days of treatment. The studied antibiotics possessing low MICs against R. equi strains were amikacin, ciprofloxacin, erythromycin, imipenem, minocycline, rifampin, and vancomycin. Vancomycin, imipenem, and rifampin were the most effective agents in monotherapy. On the other hand, amikacin, ciprofloxacin, erythromycin, and minocycline alone were not active in this model. The most active drug combinations were those including vancomycin. No antibiotic-resistant mutants were selected in vivo with treatment involving any drugs used alone or in combination. Although the treatment recommended until now for R. equi infections is rifampin plus erythromycin, this study suggests that antibiotic combinations which include vancomycin may be the most effective in vivo.

Actinomycetales Infections↗
PubMed1992

Rhodococcus equi infection in patients with AIDS.

Rhodococcus equi is an emerging opportunistic pathogen of HIV-I infected patients. It is an aerobic, Gram-positive coryneform bacterium which acts as a facultative intracellular micro-organism, multiplying in the phagosome of macrophages. Eighteen cases of R. equi infection in HIV-I positive patients have now been reported. Sixteen of these had pneumonia, of which 12 had cavitating lung lesions. A history of contact with farm animals, which are the primary hosts of R. equi, was found in only three patients. There was a delay in establishing a definite diagnosis in most cases as this depended upon the isolation of R. equi from sputum, bronchoalveolar lavage fluid, or blood. Treatment included surgical resection in five patients and erythromycin with a second antibiotic in 13 cases, but II of the 18 patients died from the infection. In this report we describe our experience of R. equi pneumonia in two AIDS patients and review the published cases of the disease in man.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Vertebral osteomyelitis due to Rhodococcus equi in a liver transplant recipient.

Rhodococcus equi is a rare but well-documented cause of cavitary pneumonia in immunocompromised patients. In this report the first case of R. equi infection manifesting as vertebral osteomyelitis is described. A 39-year-old liver transplant recipient presented with recurrent pneumonia and a pleura-based lung abscess and subsequently developed osteomyelitis of the lower thoracic spine. Surgical debridement and prolonged treatment with rifabutin and clarithromycin resulted in clinical cure. In the literature, 12 other cases of R. equi infection in solid-organ transplant recipients have been reported. Ten of these patients had documented pulmonary disease and seven had extrapulmonary manifestations. Prolonged antibiotic therapy and surgical drainage resulted in clinical improvement in > 90% of the reported cases.

Actinomycetales Infections↗
PubMed2003

Cavitary pneumonia due to Rhodococcus equi in a heart transplant recipient.

Rhodococcus equi is an uncommon human pathogen that usually affects immunocompromised patients. We present a case of a 68-year-old male heart transplant recipient, who developed rhodococcal pneumonia with secondary bacteremia 10 months post-transplant. The patient was a retired carpenter who was involved in breeding of horses. He responded completely to the treatment with vancomycin and imipenem/cilastin, followed by oral ciprofloxacin and minocycline for total treatment duration of 5 months. This case highlights the association between an animal exposure and infection with a unique opportunistic pathogen.

Actinomycetales Infections↗
PubMed2002

Medical management of pneumonia caused by Rhodococcus equi in a renal transplant recipient.

Rhodococcus equi is an animal pathogen that occasionally causes opportunistic infections in immunocompromised patients. The most common clinical picture is one of necrotizing pneumonia with a tendency toward cavitation and the formation of abscesses. We report a case of pneumonia caused by R equi in a renal transplant patient. An excellent response was shown to antibiotic treatment. Symptoms regressed, and the progressive disappearance of the lesion was confirmed on follow-up computed tomography scans. Surgical intervention or other invasive procedures were not required. To our knowledge, 14 cases of infection by R equi in solid-organ transplant patients have been described to date. Nine were recipients of a renal allograft. Surgery was required in many of these patients, and all the renal transplant recipients required the use of invasive therapeutic techniques, such as pleural drainage. This is the first case of a renal transplant recipient in whom radiologic presentation was as a solid nodule without ensuing cavitation that resolved exclusively with antibiotic treatment.

Actinomycetales Infections↗
PubMed2001

Virulence-associated protein characterisation of Rhodococcus equi isolated from bovine lymph nodes.

Rhodococcus equi has a low pathogenicity in cattle, but it occasionally causes lymph node granulomas, which are detected at abattoir post mortem inspection, and must be distinguished from tuberculous granulomas. Lymph node lesions were detected in 6719 cattle, from a total of 3,263,622 cattle examined post mortem in abattoirs, in the Republic of Ireland, during 1997 and 1998. Histological examination was performed on all lesions, principally for the purpose of identifying animals with tuberculosis. A total of 1122 of the lesions were cultured on blood agar and on Stonebrinks and Lowenstein-Jensen medium containing pyruvate, because the histological findings were difficult to interpret or were suggestive of R. equi infection. R. equi was isolated from 264 lesions. Almost all of the R. equi granulomas were confined to a single lymph node, and were present predominantly in the retropharyngeal, bronchial and mediastinal lymph nodes. R. equi granulomas were present in a significantly higher proportion of the lesions detected in steers and heifers compared to cows. The prevalence in the total population of 3.3 million cattle examined post mortem was 0.008%. The 15-17kDa antigens, associated with virulence in this organism, and the 20kDa antigen, associated with intermediate virulence, were not detected in isolates from 146 cattle, analysed by immunoblot assays. A PCR assay to detect the plasmid gene encoding the 15-17kDa antigens was also negative for isolates from these 146 animals. Plasmids were not detected in 30 isolates which were examined.

Actinomycetales Infections↗
PubMed1987

Humoral immune response of foals to experimental infection with Rhodococcus equi.

Humoral immune response to Rhodococcus equi in experimentally infected foals was studied with the enzyme-linked immunosorbent assay (ELISA) method. Class-specific antibodies were measured by ELISA in the sera of foals after intratracheal or oral inoculation with R. equi ATCC 6939 or T 48 and in the lung washings of a foal after intratracheal inoculation or of normal horses. After intratracheal or oral inoculation with R. equi, serum antibodies were first detected in immunoglobulin G (IgG) followed by IgM and IgA classes, but significant levels of IgM and IgA developed only in the foal infected intratracheally with R. equi T 48. Only the foal infected intratracheally with T 48 developed pneumonia. Anti-R. equi IgG and IgA antibodies appeared in lung washings of the intratracheally infected foal. There were differences in the antibody response to R. equi among the intratracheally infected foals, the orally infected foal and the naturally infected foal. These results suggest that the humoral immune response to R. equi may be affected by the type of R. equi strain and the route and extent of R. equi exposure.

Actinomycetales Infections↗
PubMed2005

[Necrotizing pneumonia due to Rhodococcus equi in non HIV immunocompromised host. Case report and review].

Rhodococcus equi, is a grampositive intracellular bacillus, that causes infection mainly in immunocompromised hosts. We report the case of a 52 years old woman, with a systemic lupus erythematosus and a progressive 10 months evolution with cough, dyspnea, mucous-purulent sputum, occasionally hemoptysis, intermittent fever, and weight loss of 10%. With partial response to antibiotic treatment, radiological evolution of thoracic scanners evidenced the development of multiple bilateral areas of consolidation, some of them nodular. Percutaneous thoracic biopsy showed characteristic histology and microbiological analysis yielded the identification of Rhodococcus equi in both bronchoalveolar lavage and pulmonary biopsy. She received prolonged bi-associated antibiotic treatment with good clinical and radiological response. This agent must be considered in the study of immunocompromised patients that present with a prolonged evolution of pneumonia.

Actinomycetales Infections↗
PubMed1982

Capsular serotypes of Rhodococcus equi.

One hundred strains of Rhodococcus equi from various animal species and sources in Australia were examined for capsular serotype. Eighty-four of the strains fell into the existing 7 serotypes, and just under half of the strains belonged to serotype 1. Isolates from the intestines and faeces of horses, cattle, pigs and other species, and from soil, were found to belong to the same serotypes as those recovered from the lungs of foals with R. equi pneumonia. There was no clear relationships between capsular serotype and source of origin of the isolates.

Actinomycetales↗
PubMed1996

[Rhodococcus equi pneumonia in patients with HIV infection: report of 2 cases and review of the literature].

BACKGROUND: Pneumonia by Rhodococcus equi is infrequent and is associated with patients with important immunosuppression. To date 66 cases of pneumonia by Rhodococcus equi in patients with HIV infection have been published. The diagnosis, problems in determining diagnosis and treatment are discussed. MATERIALS AND METHODS: Two new cases of pneumonia by Rhodococus equi in C3 stage patients with HIV infection are reported. Diagnosis was achieved by study of bronchoalveolar lavage samples with the Apy-Coryne method and gas chromatography. RESULTS: The two patients presented pneumonia, one of which was necrotizing pneumonia with localization in the upper left lung and in the lower right lung, respectively. The clinical manifestations were characterized by respiratory involvement of a subacute course with pleural involvement in both cases and hemoptisis in one. Prolonged, combined antibiotic treatment was administered with good response in both cases. One patient died at one year of diagnosis from consumptive syndrome while the other remains asymptomatic. CONCLUSIONS: Infection by Rhodococcus equi should be suspected in HIV patients with slow evolution pneumonia, especially in the pneumonia is necrotizing. Combined i.v. antibiotic treatment is recommended and followed from 3 to 5 months with an association including clarithromycin.

Actinomycetales Infections↗
PubMedDate not supplied

[Cavitated pulmonary condensation by Rhodococcus equi, in an HIV seropositive individual].

The first clinical case described in Portugal of a human infection by Rhodococcus equi in a 35 year-old HIV1 seropositive i.v. drug user is presented. The patient was admitted to hospital due to clinical and radiological suspicion of tuberculosis. While in hospital, a Rhodococcus equi cavitated lung infection was diagnosed. By applying a triple antibiotic therapy with erythromycin, rifampin and teicoplanin along with surgical excision of the lower lobe of the right lung, we were able to clinically resolve the pulmonary infection. A brief review of Rhodococcus equi infections, especially those associated to HIV1 infected individuals is also presented with particular emphasis on the therapeutic approach.

AIDS-Related Opportunistic Infections↗
PubMed2001

Detection of antibodies against Rhodococcus equi in Alpaca (Lama pacos) in Italy.

After isolating the two virulent strains of Rhodococcus equi from Alpaca, a serological survey of Rhodococcus equi infection was carried out on 57 blood samples of Alpaca collected in Central Italy. The survey was performed with an ELISA test using a reference R. equi strain as antigen (ATCC 33701). Four (7.0%) sera (OD greater or equal to 0.3) tested positive, while five (8.77%) were considered doubtful (OD between 0.2 and 0.3). This is the first serological survey of R. equi infection in Alpaca in Italy. The results indicate that besides the horse R. equi infection could also affect some ruminant species. The ELISA test was recently introduced as a reliable diagnostic method in horses and was adapted to alpaca.

Actinomycetales Infections↗