Pulmonary nocardiosis presenting as a fungal ball in a preexisting cavity is a rare presentation. We report such a case in a 18 yrs old male patient presented with cough with expectoration & episodes of haemoptysis with a past history of tuberculosis. Diagnosis was done by microscopic examination of the resected sample & confirmed on culture.
Keywords: Fungal ball, Nocardia asteroides, pulmonary nocardiosis
Nocardiosis is an opportunistic localized or disseminated granulomatous infection caused by an aerobic actinomycetes most commonly found in soil, decomposing vegetation, organic matter as well as in fresh and salt water.  Infection most commonly occurs through inhalation. Pulmonary disease is the most common presentation in immuno-suppressed patients.
Pulmonary fungal ball is defined as a conglomeration within a lung cavity or ecstatic bronchus or inter-wined fungal hyphae matted together with fibrin, mucus and cellular debris. 
Nocardia species colonize preexisting lung cavities are producing a “fungal ball” appearance. We report here a case of fungal ball due to Nocardia asteroides that are a very rare entity.
An 18-year-old male presented with cough and expectoration with episodes of hemoptysis for 1-year. Frequency and volume of hemoptysis has increased since last 7 days.
The patient had a history of tuberculosis and was treated with antituberculosis therapy for 9 months. There was no history of hypertension and diabetes.
On general examination, there was the pallor, but there was no jaundice, clubbing or lymphadenopathy. Respiratory examination revealed decreased air entry in left upper part of the chest. Chest X-ray showed a cavitary lesion in the upper lobe of the left lung [Figure 1].
Computer tomography scan of the chest showed fibro-cavitary lesion in left upper lobe of the lung with suspected fungal ball inside the cavity [Figure 2].
On thoracotomy, the left lower lobe was normal. There was significant neovascularization of the diseased lung tissue. A thick-walled cavity with a suspected fungal ball was present in the left upper lobe.
The left upper lobe along with the cavity containing the fungal ball was resected, and tissue was sent for histopathological and microbiological examination.
Hematological examination revealed hemoglobin of 7.6 g/dl, total leucocyte count was 10,800 cells/mm 3 with neutrophil count of 74%, lymphocyte 20% and eosinophil 6%. A part of the specimen was subjected for 10% KOH mount, Gram-staining and modified acid-fast staining, and the other was inoculated on blood agar and Sabouraud’s dextrose agar (SDA) with antibiotics. SDA inoculated media were incubated at 25°C and were observed daily for up to 3 weeks. Inoculated blood agar was incubated at 37°C under aerobic and anaerobic condition and observed daily for 7 days.
On 10% KOH mount very fine narrow, delicate branching intertwined filaments were seen. Gram stain revealed Gram-positive, thin beaded branching filamentous bacteria. Modified Z-N staining showed many branching acid-fast filamentous bacteria [Figure 3]. Culture on blood agar plate revealed glabrous dry, wrinkled, milky white colonies after 5 days of aerobic incubation. The isolate was identified to be N. asteroides by standard biochemical test.  No growth was observed on SDA. Histopathological examination showed thin branching filaments with mixed cellular response of polymorphonuclear leukocytes, macrophages and lymphocytes.
Antibiotic susceptibility result of the isolate showed sensitivity to amikacin, cotrimoxazole, imipenem, levofloxacin, amoxyclav and resistant to gentamicin, cefuroxime and penicillin.
Our patient was treated with cotrimoxazole for 2 months and showed improvement and the treatment are continuing.
Pulmonary nocardiosis is the most common clinical presentation as the infection occurs primarily through respiratory route. Individuals with a normal immune system can acquire this infection, but the main risk factor for nocardiosis is a weakened immune system or chronic lung disease. Persons with lymphoma, other malignancies and HIV infection are at increased risk.
Nocardia asteroids that occur in bacillary, cocobacillary and mycelial forms are Gram-positive and variably acid-fast bacteria. They tend to affect lung, brain and skin. Pathogenic species of Nocardia can be found in house dust, beach sand, garden soil and swimming pool. The organisms are readily aerosolized with dust especially in dry areas.
The pace and course of infection are closely related to the immune competence of the host. In immunocompetent host the infection is chronic, localized to a single organ or region, whereas in immunocompromised host dissemination occurs through blood stream involving skin and central nervous system (CNS).
It has a universal distribution affecting people mainly between 20 and 50 years of age.  Pulmonary disease like tuberculosis leaves cavity in lungs in which spores can grow into fungal ball. the most common cause of fungal ball is Aspergillus spp. whereas Pseudoallescheria boydii, Candida spp, Streptomyces, Penicillium, Cladosporium and Coccidiodes immites are other etiological agents.  Rarely, Nocardia spp. invade preexisting lung cavities producing a fungal ball appearance.
Our patient was not immunocompromised, but he has a history of tuberculosis that might have formed a cavity in the lungs. The constant exposure to contaminated air, soil, grass and water in a rural background might have caused the infection, which presented as a fungal ball in the preexisting cavity.
Untreated pulmonary nocardiosis can present as tuberculosis having fever, weight loss, nonproductive cough and hemoptysis. The clinical and radiographic finding in pulmonary, disseminated and cutaneous nocardiosis are nonspecific and may be mistaken for a variety of other bacterial infection including actinomycosis, tuberculosis and fungal infection as well as malignancies affecting the lungs, skin and brain. 
The diagnosis of nocardiosis requires the isolation and identification of the organism from a clinical specimen. It is rarely considered as a contaminant in the laboratory, and each isolate must be carefully evaluated. Microscopic and macroscopic examination of a specimen submitted for culture is the first step in providing a diagnosis.  Species typification is very important since different species have different resistant profiles, and this information is crucial in order to guide the antibiotic treatment. 
Staining with modified acid-fast stain and especially Gram stain in particular is important to provide a rapid presumptive diagnosis, while awaiting the result of the culture. Surgery was the first line of treatment before the introduction of sulfonamides. Sulfonamides, including sulfadiazine and sulfisoxazole have been the antimicrobials of choice to treat nocardiosis for the past 50 years despite bacteriostatic activity.  Trimethoprim, sulfamethoxazole is now most frequently used to treat this infection. Alternatives to sulfonamide include amikacin, imipenem, meropenem, ceftriaxone, cefotaxime, minocycline, moxifloxacin, levofloxacin, linezolid, tigecycline and amoxicillin, clavulanic acid. ,
For pulmonary involvement and disseminated nocardiosis without CNS involvement, the patient should be treated for 6 months at least. 
Due to the difficulty, slowness of culture growth and lack of available serological test, Nocardiosis should be included in the differential diagnosis of patients in whom an apparent pulmonary infection cannot be rapidly diagnosed. High index of suspicion is required to diagnose and treat the infection due to Nocardia spp. which is a rare cause of pulmonary fungal ball.
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]