Surgical management of localized thoracic infections in immunosuppressed patients

Persistent Rhodococcus equi infection in a renal transplant patient: case report and review of the literature

Rhodococcus equi is a pathogen that mainly causes infection in immunocompromised hosts. We report a case of relapsing R. equi pulmonary infection in a 57-year-old male renal transplant recipient who was treated with 12 months of antibiotics, adjunctive surgery, and a reduction in his immunosuppression. He suffered from relapsing disease, treatment-related complications, and ultimately died of Pneumocystis pneumonia. Case reports in the literature portray a good cure rate for transplant-related R. equi infections, with shorter durations of antibiotics. The case illustrates the difficulties in the management of R. equi infections. Forty cases from the literature were reviewed and compared in terms of epidemiology, location of infection, transplant type, immunosuppression used, treatment used, outcomes, and possible exposures.

Rhodococcus equi pneumonia in a renal transplant patient: a case report and review of literature

Immunocompromised patients are susceptible to many pathogens, including those that are predominantly problems in veterinary medicine. We report a case of a 42-yr-old white male who presented 19 months post-cadaveric renal transplant (for IgA nephropathy) with a 5 d history of nausea, vomiting, abdominal cramping and diarrhea. Admission chest X-ray revealed a suspicious mass lesion in the left lower lobe. Computed tomography (CT) guided biopsy of the lesion showed a large zone of CD68 +ve histiocytes in a non-caseating granuloma. Gram stain revealed multiple gram-positive rods within the histiocytes, which were eventually identified as R. equi. After 4 months of therapy with fluoroquinolones (Avelox) and Azithromycin a repeat CT showed complete resolution of the lesion. We reviewed the literature with special focus on the clinical features, challenges in diagnosis, and treatment of this rare infection (especially in the transplant patients who are also on immunosuppressive therapy).

Rhodococcus equi pulmonary infection in a pancreas-alone transplant recipient: consequence of intense immunosuppression

We report the case of a pancreas-alone transplant recipient who developed Rhodococcus equi pneumonia after receiving multiple courses of antilymphocyte therapy for the treatment of recurrent acute pancreas allograft rejection. We also review and discuss the diagnosis, clinical course, and treatment of 18 cases of R. equi infection reported in solid organ transplant recipients. The lung is the most common primary site of infection, but R. equi infection is difficult to diagnose because of the pleomorphic, gram-positive, and partially acid-fast nature of the organism. Treatment usually involves a combination of antibiotics including rifampin, macrolides, vancomycin, and ciprofloxacin. The optimal duration of therapy is unknown, but relapse is common if the duration of treatment is less than 14 days. The duration of therapy should be guided by clinical recovery, culture results, and radiographic findings. Monitoring levels of immunosuppressive agents-such as tacrolimus and cyclosporine-is needed in order to avoid clinically significant drug interactions with rifampin or the macrolides when these agents are used in order to treat R. equi infection in the transplant population.

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.

Rhodococcus equi infection in transplant recipients: case report and review of the literature

BACKGROUND

Rhodococcus equi is an opportunistic pathogen that usually causes infection in immunocompromised hosts, mainly human immunodeficiency virus-positive patients, yet solid organ transplant recipients may be affected as well. Infections in this group of patients have not been sufficiently analyzed.

METHODS

We report an R equi pneumonia in a heart transplant recipient and review another 11 cases.

RESULTS

Infection appeared a mean of 49 months (range 1-180) after transplantation. Lung was primarily involved in 10 cases (83.3%). The remaining two cases presented with a paravertebral abscess and a purulent pericarditis. Invasive techniques were necessary to reach the diagnosis in nine cases. One patient healed with surgical resection of the lesion; the remaining 11 received antimicrobial agents. Six of them required additional surgical treatment. Three patients died.

CONCLUSIONS

Clinicians should consider R equi when evaluating a solid organ recipient with an asymptomatic lung nodule. Microbiology laboratories should be alerted in these cases because it could be mistaken for a contaminant diphtheroid and will not respond to the standard empirical therapy.

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.

[Rhodococcus equi pulmonary abscess in HIV infection]

RE is a well-known Gram positive bacillus which is usually pathogenic in animals. Disease in humans is rare, but incidence has clearly increased with the advent of AIDS. In humans, RE predominantly infect people with impaired cellular immunity so that it is considered an opportunistic agent. Its must common manifestation in immuno-compromised patients is a slowly progressive pneumonia which may cavitate. Even with early diagnostic and optimal and prolonged antibiotic therapy, the mortality of RE, infections remain high (20 to 55%). Problems in clinical and therapic management are illustrated in our two cases of cavitated pneumonia in two AIDS patients.

The medically important aerobic actinomycetes: epidemiology and microbiology

The aerobic actinomycetes are soil-inhabiting microorganisms that occur worldwide. In 1888, Nocard first recognized the pathogenic potential of this group of microorganisms. Since then, several aerobic actinomycetes have been a major source of interest for the commercial drug industry and have proved to be extremely useful microorganisms for producing novel antimicrobial agents. They have also been well known as potential veterinary pathogens affecting many different animal species. The medically important aerobic actinomycetes may cause significant morbidity and mortality, in particular in highly susceptible severely immunocompromised patients, including transplant recipients and patients infected with human immunodeficiency virus. However, the diagnosis of these infections may be difficult, and effective antimicrobial therapy may be complicated by antimicrobial resistance. The taxonomy of these microorganisms has been problematic. In recent revisions of their classification, new pathogenic species have been recognized. The development of additional and more reliable diagnostic tests and of a standardized method for antimicrobial susceptibility testing and the application of molecular techniques for the diagnosis and subtyping of these microorganisms are needed to better diagnose and treat infected patients and to identify effective control measures for these unusual pathogens. We review the epidemiology and microbiology of the major medically important aerobic actinomycetes.

Distribution and antimicrobial susceptibility of Rhodococcus equi from clinical specimens

Rhodococcus equi, an unusual gram positive aerobic actinomycete, was first described as a respiratory pathogen of livestock in 1923. Reports of human clinical illness have emphasized R. equi as a cause of invasive pulmonary infection in severely immunocompromised patients and, recently, have implicated it as a cause of pneumonia, bacteremia and disseminated infection in HIV-infected patients. To determine the distribution of R. equi we evaluated 107 isolates referred to the Centers for Disease Control (CDC) during the period January 1973 through December 1990. The sites of these 107 isolates (101 patient and 6 animal isolates) were: blood (32 isolates), sputum (30), lung tissue (13) and other site (32). Before 1983, when the first R. equi isolate from an HIV-infected patient was received, CDC received a total of 52 patient isolates. In addition, during this 10 year period, R. equi isolates were received from more than one site from only one patient. However, during the two year period 1989-1990, we identified 8 patients with underlying HIV infection and R. equi pneumonia who accounted for 29 of 35 (83%) R. equi patient isolates; 6 of these patients also had bacteremia and three died with disseminated R. equi infection. No isolates were resistant to amoxicillin-clavulanate, ampicillin-sulbactam, gentamicin or imipenem, and few (less than 5%) isolates were resistant to erythromycin, rifampin, tetracycline, and trimethoprim-sulfamethoxazole. These results suggest that HIV-infected patients, in particular, are predisposed to develop invasive pulmonary, fatal disseminated R. equi infection (or both), and appropriate antimicrobial susceptibility testing of clinical isolates may improve the effectiveness of therapy of R. equi-infected patients.

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.

A case of Rhodococcus equi brain abscess

We treated a patient with acquired immunodeficiency syndrome for a brain abscess caused by Rhodococcus equi, an actinomycete that usually infects the lung in immunosuppressed hosts. Rhodococcus equi brain abscess is an extremely rare lesion that has never been reported in a patient with acquired immunodeficiency syndrome. The infection was cured by lengthy therapy with multiple antibiotics after aspiration of the lesion to identify the infective organism and determine its sensitivity to antibiotics.

Rhodococcus equi: an animal and human pathogen

Recent isolations of Rhodococcus equi from cavitatory pulmonary disease in patients with AIDS have aroused interest among medical microbiologists in this unusual organism. Earlier isolations from humans had also been in immunosuppressed patients following hemolymphatic tumors or renal transplantation. This organism has been recognized for many years as a cause of a serious pyogranulomatous pneumonia of young foals and is occasionally isolated from granulomatous lesions in several other species, in some cases following immunosuppression. The last decade has seen many advances in understanding of the epidemiology, pathogenesis, diagnosis, treatment, and immunity to infection in foals. The particular susceptibility of the foal is not understood but can be explained in part by a combination of heavy challenge through the respiratory route coinciding with declining maternally derived antibody in the absence of fully competent foal cellular immune mechanisms. R. equi is largely a soil organism but is widespread in the feces of herbivores. Its growth in soil is considerably improved by simple nutrients it obtains from herbivore manure. About one-third of human patients who have developed R. equi infections had contact in some way with herbivores or their manure. Others may have acquired infection from contact with soil or wild bird manure. R. equi is an intracellular parasite, which explains the typical pyogranulomatous nature of R. equi infections, the predisposition to infection in human patients with defective cell-mediated immune mechanisms, and the efficacy of antimicrobial drugs that penetrate phagocytic cells.

Rhodococcus equi--an easily missed opportunistic pathogen

Over the last 10 years Rhodococcus equi has been identified as an important, albeit very rare, opportunistic pathogen. As the number of patients immunocompromised from HIV infection grows, this microorganism will likely become of increasing clinical importance. Infection with R. equi is usually insidious, causing progressive pulmonary disease that is typically pleural based at the time of microbiological diagnosis. As in the case we present, the clinical and microbiological diagnoses may be significantly delayed, either by the common pitfalls encountered in the laboratory identification of R. equi, or by the failure to recognize the pathogenic potential of the isolate. R. equi infection should be suspected in immunocompromised patients with pneumonia, when a pure or predominant growth of aerobic, non-sporeforming gram-positive bacilli is found on cultures of bronchoalveolar lavage fluid and other pulmonary pathogens have been excluded.

Rhodococcus equi: an emerging opportunistic pathogen?

Human infection with Rhodococcus equi is apparently rare with most published reports describing the development of lung abscesses in immunocompromised hosts. Of only 18 cases of infection previously recorded, four have recently occurred in patients with the acquired immune deficiency syndrome (AIDS). In Australasia, R. equi has frequently been isolated from soil and infected farm animals yet no human infections have been reported thus far. Three cases of R. equi infection have occurred in New Zealand and, collectively, they cover a wider spectrum of disease than that previously recognised. The natural history of R. equi infections, their clinical features and treatment are described in the light of our recent experience.

Osteomyelitis caused by Rhodococcus equi in a renal transplant recipient

We report the first case of osteomyelitis due to Rhodococcus equi, which occurred in a renal transplant patient. Infection with this organism is rare and usually causes a distinct clinical syndrome resembling pulmonary tuberculosis. We investigated by time-kill curve analysis various antimicrobial combinations for in vitro efficacy. The literature is briefly reviewed, and aspects of diagnosis and therapy are discussed.

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.

Lung abscess due to Corynebacterium equi. Report of the first case in a patient with acquired immune deficiency syndrome

A lung abscess and persistent bacteremia due to Corynebacterium equi are described in a bisexual man with the acquired immune deficiency syndrome (AIDS). Eleven of the 12 previously reported cases have occurred in immunocompromised humans. The occurrence of this infection in a patient with AIDS has not been previously described. Development of resistance to beta-lactam antibiotics was noted following initial therapy. Because this organism resembles nonpathogenic organisms, it may easily be overlooked despite its ability to cause serious infection and persist even with aggressive antimicrobial and surgical therapy.

Thoracic mass lesions in immuno-incompetent patients

An aggressive surgical approach was used in the diagnosis and treatment of seven immuno-incompetent patients who presented with focal thoracic mass lesions. In five of the seven patients, minor diagnostic procedures had failed to provide a diagnosis. All seven patients were subjected to exploratory thoracotomy with resection and/or drainage of the involved area. Two patients had parenchymal masses, two had lung abscesses, two had empyemas with trapped lung, and one had a bronchial fistula. An accurate diagnosis and full resolution of the intrathoracic process was obtained in all patients. There was little morbidity and no operative mortality in this series. Resection of focal thoracic lesions in immuno-incompetent patients combines accurate diagnosis with precise therapy and is well tolerated in this high risk group of patients.

Lung abscess due to Corynebacterium equi in a renal transplant recipient

A case of Corynebacterium equi infection in a renal transplant recipient is reported. This not uncommon pathogen of farm animals caused a lung abscess in a graft recipient who had received continuous immunosuppression with azathioprine and prednisone for seven years. Antibiotic therapy yielded radiological improvement, although the patient died from other causes. C. equi joins a growing list of rare opportunistic organisms which may cause disease in subjects who have received transplants.

Immunology and thoracic surgery

This report reviews the current status of three types of diseases in which knowledge of immunology is changing the practice of thoracic surgery. Evidence is presented for myasthenia gravis being an autoimmune disease. Thymectomy is widely considered to be the therapy of choice for patients with generalized myasthenia regardless of age or sex. Opportunistic pulmonary infections of unusual types are being encountered frequently in patients receiving immunosuppressive drugs for organ transplantation or malignancy. The important role of bronchial brushing and open lung biopsy is stressed. Immunotherapy of several types is currently being investigated experimentally and clinically and promises to change therapy for bronchogenic and esophageal neoplasms.

The incidence and management of pulmonary mycosis in renal allograft patients

A retrospective analysis of 193 renal transplant recipients yielded 15 patients who developed pulmonary mycosis posttransplantation and one case in which mycotic lung infection existed at the time of transplant surgery. Agent responsible for infection included Nocardia asteroides in 8 cases, Asperigillus flavus in 5 cases, Cryptococcus neoformans in 4 patients and Candida albicans in 2 cases. Two cases had mixed mycotic infections. Ten patients died, of which 7 had diagnosis established antemortem. Two cases had diagnosis established by thoracotomy and 1 case by transtracheal aspiration. Problems in establishing accurate diagnosis are discussed with emphasis placed on the need for more frequent use of transtracheal aspiration and thoracotomy for precise diagnosis.