Pulmonary nocardiosis in human immunodeficiency virus infection: a tuberculosis mimic.HS Subhash, DJ Christopher, A Roy, AM Cherian
Department of Medicine and Respiratory Medicine, Christian Medical College and Hospital, Vellore - 632 004, Tamilnadu, India. , India
Correspondence Address: Source of Support: None, Conflict of Interest: None PMID: 11590288
Source of Support: None, Conflict of Interest: None
Patients with human immunodeficiency virus (HIV) infection are prone to develop pulmonary infections like nocardiosis. It is often misdiagnosed as pulmonary tuberculosis since the manifestations are similar. A twenty-seven years old male presented with fever, cough with expectoration and weight loss for two months. Chest radiograph showed opacity in the right mid zones. Sputum smears were negative for acid fast bacilli (AFB) and revealed gram positive branching filamentous organisms resembling Nocardia species. Subsequently, Nocardia was grown on sputum culture. HIV antibody was positive by ELISA test. He was treated with co-trimoxazole. If sputum is repeatedly tested negative for AFB in the setting of radiological suspicion of tuberculosis, testing for Nocardia species should be considered in the HIV-infected patients.
Keywords: AIDS-Related Opportunistic Infections, diagnosis,Adult, Anti-Infective Agents, therapeutic use,Case Report, Diagnosis, Differential, Enzyme-Linked Immunosorbent Assay, Human, Male, Nocardia, isolation &purification,Nocardia Infections, diagnosis,drug therapy,microbiology,radiography,Pneumonia, Bacterial, diagnosis,drug therapy,microbiology,radiography,Radiography, Thoracic, Treatment Outcome, Trimethoprim-Sulfamethoxazole Combination, therapeutic use,Tuberculosis, Pulmonary, diagnosis,
Pulmonary nocardiosis is known to occur in immunocompromised patients and in those with underlying chronic lung diseases. With the increase in prevalence of human immunodeficiency virus (HIV) infection and the acquired immunodeficiency syndrome (AIDS) in our country, we are likely to have an increase in the incidence of pulmonary nocardiosis. It is often misdiagnosed as pulmonary tuberculosis since its clinical and radiological manifestations are similar to the latter. Given the increased likelihood of smear negative disease in the setting of tuberculosis, we are likely to face more instances of such misdiagnoses in our country. There are occasional reports of nocardiosis in patients with HIV infection., We present a patient with nocardiosis who also had HIV infection.
A 27-year-old male presented with cough productive of moderate amounts of muco-purulent expectoration low-grade intermittent fever, anorexia and weight loss of two months’ duration. There was no history of sexual promiscuity or intra-venous drug abuse. Physical examination revealed a thinly built individual, who was not obviously emaciated. Pulse rate was 82 per minute and blood pressure 110/70 mm Hg. There was no pallor, icterus, cyanosis, finger clubbing, significant lymphadenopathy or pedal oedema. Examination of the respiratory system revealed crackles in the right mammary, infra-axillary and infra-scapular areas. Examination of other systems was non-contributory.
The haemoglobin was 9.2 grams% and the total leucocyte count was 11,500/cu mm with the differential count showing 88% polymorphs, 8% lymphocytes, 2% eosinophils and 2% band forms. Serum electrolytes, creatinine, liver function tests and plasma glucose were normal. Frontal radiograph of the chest showed heterogeneous opacity in the right lung parenchyma in the right mid zones [Figure - 1]. Three consecutive morning samples of sputum were negative for acid fast bacilli (AFB). Gram stain of the sputum smear revealed gram positive branching filamentous organisms resembling Nocardia species. HIV antibody was positive by ELISA test. He was started on therapy with co-trimoxazole. Subsequently, Nocardia was grown on sputum culture, and was found to be sensitive to co-trimoxazole. Mycobacterial culture of a sputum sample was negative.
Patients infected by HIV are predisposed to develop a variety of common and uncommon pulmonary infections. Some unusual infections are those caused by Rhodococcus, Nocardia, Cryptococcus and Aspergillus. Of the various species of Nocardia that are pathogenic to man, N. asteroides is the most common. Diagnosis of pulmonary nocardiosis can be made on the basis of a positive sputum culture in an immunocompromised host.,
Most cases of nocardiosis present with respiratory symptoms. The most common symptoms at presentation are chronic cough, chest pain, dyspnoea and haemoptysis. Thus pulmonary nocardiosis can mimic tuberculosis. This is important to bear in mind, particularly in areas where the prevalence of tuberculosis is high and this has been shown by two Indian studies in non-HIV subjects. In both these studies more than two thirds of the patients diagnosed to have pulmonary nocardiosis were initially diagnosed as having tuberculosis. About 5% of the patients with proven pulmonary tuberculosis were shown to have co-infection with Nocardia.,
Pulmonary nocardiosis is a chronic disease which can rarely have an acute course and 85% of the infections reported in one series were considered to be serious. Chronic nocardiosis carries a mortality rate of 33% and acute disease; 66 -72%.,
Reports have suggested that there is usually a delay in the diagnosis of pulmonary nocardiosis of about 6 weeks (range: 2 weeks - 4 years). This is attributed to a lack of awareness. The usual reason for requesting culture studies for the detection of Nocardia species is when a patient does not respond to the usual anti-bacterial or anti-tuberculous treatment.
Chest radiological findings of pulmonary nocardiosis in advanced HIV infection include alveolar infiltration, cavitation, pleural effusion, and reticulonodular pattern. A study that evaluated the computed tomography finding of chest in patients with Nocardiosis and AIDS showed multiple nodules in almost all patients and cavitation occurred in 80% of the patients. Bronchial washings are shown to be useful for isolation of nocardia. Nocardia may take several days to weeks to grow in culture. It has been suggested that if nocardiosis is considered in the differential diagnosis, the duration of culture should be prolonged and the use of selective media might have to be considered.,
Nocardiosis presents at an advanced stage of HIV infection and can be fatal in advanced HIV infection. In 19 of 30 patients in a series, nocardiosis caused or contributed to death. Delayed diagnosis, extensive disease and early discontinuation of treatment were associated with a poor outcome.
In an autopsy study of 247 patients who died of HIV-related illnesses, 10 patients (4%) had nocardiosis and among those with AIDS defining illnesses, 5 % had this disease. Of the 10 patients diagnosed to have nocardiosis, 4 had been initially misdiagnosed as having pulmonary tuberculosis. The mean survival after establishing the diagnosis of nocardiosis was only 5 days. In another autopsy study, of HIV deaths the cause of death could be attributed to pulmonary nocardiosis in 2 out of 11 patients treated for pulmonary tuberculosis. In India, the prevalence of nocardiosis as reported in 1973 was 4.6% among patients with suspected tuberculosis.
Although nocardiosis resembles tuberculosis, first line anti-tuberculous drugs have no role in its treatment. Therefore, it is important to establish a definitive diagnosis. Nocardiosis should be considered in the differential diagnosis in any patient with unexplained cavitary or granulomatous pulmonary disease not responding to therapy. If sputum is repeatedly tested negative for acid-fast bacilli in the setting of radiological suspicion of tuberculosis or if the patient’s condition worsens despite anti-tuberculous therapy, testing for Nocardia species should be considered.
It has been suggested that microscopic morphology can be suggestive enough to warrant empiric therapy for nocardiosis while awaiting culture results, especially in seriously ill patients and in those with impaired host defense. Empiric treatment should be commenced with sulphonamides or other appropriate anti-nocardial antibiotics. A study that looked at the anti-microbial sensitivity pattern showed 100% sensitivity to Amikacin, 83% to Imipenem, 71% to Cefotaxime and 71% to Cotrimoxazole.
Prognosis for nocardiosis in patients with HIV infection depends on the rapidity with which the diagnosis is established. Early diagnosis can be life-saving.
We thank Dr Shyam Kumar lecturer in the department of radiodiagnosis for his help in completing this article.
[Figure - 1]