|Year : 2015 | Volume
| Issue : 1 | Page : 48-51
Nocardial brain abscess: Need for rapid diagnosis and aggressive management
Rengaswamy Sukanya1, Bindiganavile Gokul1, Vasani Viral2, Deshpande Rajakumar2
1 Department of Microbiology, SRL at Fortis Hospitals, BG Road, Bengaluru, India
2 Department of Microbiology, Fortis Hospitals, Bengaluru, Karnataka, India
|Date of Web Publication||16-Jun-2015|
Department of Microbiology, SRL at Fortis Hospitals, BG Road, Bengaluru
Source of Support: None, Conflict of Interest: None
Nocardiosis is an opportunistic disease that occurs commonly in immunocompromised patients and also sometimes in immunocompetent individuals. The most common disease sites include lung, skin and central nervous system (CNS). Nocardial brain abscesses are rare CNS infections with high mortality rate reaching 34% which is considered the highest amongst brain abscesses caused by microorganisms. We report two cases of nocardial brain abscesses in patients with pre-existing lung disease. The first case presented with seizures and the second with hemiparesis, hemianopia and pleural effusion. Magnetic resonance imaging (MRI) brain showed space occupying lesions, thought to be tuberculoma or malignant brain tumor. Per operatively they were found to be abscesses. The Gram stain of pus from both cases and cultures of pus and pleural fluid yielded Nocardia farcinica. Histopathology of brain tissue was also corroborative. Both patients were started on long term therapy of Sulphamethoxazole-Trimethoprim (Co-trimoxazole) and in the second case of disseminated nocardiosis, Ceftriaxone and Linezolid was added. These cases highlight the importance of including nocardial abscesses as differential diagnosis in immunosuppressed patients presenting with neurological deficits and abnormal MRI. Multisystem nocardiosis may not be as rare as assumed. Thus an increased vigilance towards diagnosis and appropriate treatment including surgical intervention is required for reducing morbidity and mortality.
Keywords: Brain abscess, immunosuppressed, Nocardia farcinica
|How to cite this article:|
Sukanya R, Gokul B, Viral V, Rajakumar D. Nocardial brain abscess: Need for rapid diagnosis and aggressive management. J Acad Clin Microbiol 2015;17:48-51
|How to cite this URL:|
Sukanya R, Gokul B, Viral V, Rajakumar D. Nocardial brain abscess: Need for rapid diagnosis and aggressive management. J Acad Clin Microbiol [serial online] 2015 [cited 2022 Dec 5];17:48-51. Available from: https://www.jacmjournal.org/text.asp?2015/17/1/48/158810
| Introduction|| |
0Nocardia infections are rare but potentially fatal bacterial opportunistic infections, caused by Gram-positive, weakly acid-fast filamentous, branching aerobic bacilli. They are strongly associated with immunosuppression especially in patients with weakened cell-mediated immunity. Nocardia farcinica is a rare species causing localized and disseminated infections in humans, including pulmonary infections, brain abscesses, and bacteraemia, especially in immunocompromised patients. The central nervous system (CNS) is involved in approximately 44% of cases, usually in patients having pulmonary infection  and incidence of disseminated disease is 25-40%.  The imaging findings of nocardiosis are not specific as it depends on the stage of the infectious process at the time of imaging. In this article, two cases of N. farcinica infections, one with a solitary cerebral abscess and the other a disseminated infection involving the pleura and CNS is discussed.
| Case reports|| |
A man aged 68 years, presented to emergency department of our hospital with a history of gradually progressive weakness followed by partial seizures which evolved into status epilepticus. He developed right sided hemiparesis (upper limb > lower limb) grade (3/5 vs. 2/5). No cranial nerve deficits were observed and sensorium was preserved. He was a known case of hypertension and interstitial lung fibrosis, on treatment with steroids (prednisolone) for 4 years.
Magnetic resonance imaging (MRI) showed an irregular, lobulated necrotic mass lesion of 26 mm diameter with dense perilesional oedema in the left posterior frontal deep white matter [Figure 1]. A differential diagnosis of either malignancy or tuberculoma was considered.
|Figure 1: Irregular, lobulated necrotic mass lesion with dense perilesional edema-left posterior frontal deep white matter|
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He underwent left parietal mini craniotomy for biopsy of lesion which revealed an abscess. The pus drained was sent for Gram's stain, culture and histopathology.
The patient was prescribed broad spectrum intravenous antibiotics (Ceftriaxone 1 g twice daily for 14 days), and empirical antituberculous drugs (Rifampicin 600 mg orally once daily, Isoniazide 300 mg orally once daily, Pyrazinamide 1.5 mg orally once daily, and Ethambutol 1.2 g orally once daily).
Gram's stain of the pus sample showed filamentous, branching Gram-positive rods [Figure 2]. Modified Ziehl-Neelsen (ZN) staining showed the presence of long, acid-fast branching filamentous bacilli [Figure 3]. The histopathology revealed abscess formation and macrophages.
|Figure 2: Gram's stain of the pus-fi lamentous, branching, beaded Gram-positive rods|
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|Figure 3: Modified Ziehl– Neelsen staining-long, acid-fast branching filamentous bacilli|
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Culture showed dry, wrinkled and pigmented colonies identified as Nocardia species [Figure 4]. Isolate was sent to Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh for speciation and was identified as N. farcinica by DNA sequencing of 16S and heat shock protein region. Empiric treatment was stopped including anti tubercular therapy and he was started on Co-trimoxazole (Trimethoprim [TMP], 400 mg with Sulfamethoxazole [SMX], 2 g) 3 times daily for 6 weeks. Patient reported to the emergency department again after 5 days with right sided focal seizures. He was drowsy, disoriented with Glasgow coma scale (GCS) of E3 M6 V4 and right sided hemiparesis. Computed tomography (CT) brain showed dense white matter oedema with focal cystic dense lesion. Mass effect on the left lateral ventricle with shift of midline towards right was seen [Figure 5].
|Figure 5: Computerized tomography brain-dense white matter oedema with focal cystic dense lesion|
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The patient developed leucopenia with metabolic abnormality and hence Co-trimoxazole-double strength was withheld and restarted after the blood counts returned to normal. The antimicrobials were changed to a combination of Minocycline (100 mg twice daily) for 3 weeks and Linezolid for 6 weeks with a short course of steroids.
On follow-up examination after 3 weeks, the patient showed marked improvement clinically and was discharged in stable condition on long term antibiotic therapy Linezolid with Co-trimoxazole-double strength for 5 weeks. The patient was followed-up for 2 years and there was no recurrence of seizures or weakness.
A woman aged 57 years, a known case of inflammatory bowel disease of 2 months duration and pulmonary Koch's disease since 45 days was referred to the emergency department of our hospital with complaints of fever, weakness of left side of body, left hemianopia and abdominal distension for 2 days without obvious focal motor or sensory deficits.
Magnetic resonance imaging with contrast showed right occipital lobe mass with perilesional oedema and midline shift [Figure 6]. Thus a provisional diagnosis of tuberculoma of brain was made.
|Figure 6: Magnetic resonance imaging with contrast-occipital lobe mass with perilesional oedema and midline shift|
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Surgical excision was delayed due to pleural effusion. After pleural aspiration patient had a bout of generalised tonic clonic seizure, with de-saturation and hypotension. Patient was shifted to the Intensive Care Unit, stabilised and then taken up for right parieto occipital craniotomy, excision of the lesion and aspiration of the abscess. Post-operatively her sensorium worsened. Her GCS dropped to E1VtM2 with pupillary asymmetry and hypotension. CT scan of the brain revealed left middle cerebral artery territory infarct and was managed conservatively.
The Gram stain of the pus showed presence of Gram variable filaments and acid-fast filamentous bacilli on modified ZN. Culture of the abscess yielded dry, pigmented colonies on blood and chocolate agar which grew better at higher temperatures of incubation (45°C). Gram stain of these colonies showed Gram-positive, thin bacilli with pronounced branching and was reported as Nocardia species. Isolate was sent to PGIMER, Chandigarh for speciation and was identified as N. farcinica by DNA sequencing.
The histopathology of brain revealed filamentous bacteria on Gomori methanamine silver stain [Figure 7]. The patient was treated with intravenous Co-trimoxazole (TMP, 400 mg SMX, 2 g) thrice daily and 1 g Meropenem thrice daily for 10 days as there was disseminated nocardiosis with underlying immunosuppression.
|Figure 7: Filamentous, branching bacilli on special stain (Gomori's methenamine silver)|
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The patient with GCS of E2 M2 V1 and on ventilator support was shifted to another hospital on request and finally expired after a week of treatment at the other hospital.
| Discussion|| |
Nocardial infections are acquired through the respiratory tract or skin, and have a tendency to disseminate haematogenously from the primary site of infection to brain, kidney, joints, bones and eyes. Sulfonamides are preferred empirically for the treatment. 
The predisposing factors of nocardiosis are malignancies, immunodeficiency states, iatrogenic immunosuppression following organ transplantation, diabetes mellitus, renal disease, collagen vascular diseases, alcoholism, tuberculosis, chronic lung disease, trauma or abnormal phagocytic activity. 
Nocardia farcinica infections, have higher fatality rates than nocardiosis caused by other species of the genus Nocardia and are 3 times more common in men than in women.  Because of the aggressiveness, tendency to disseminate, and the resistance of the organism to cephalosporins, a delay in appropriate therapy can have serious consequences in N. farcinica infections.  Both the cases presented here were immunosuppressed with steroid therapy for other clinical conditions and the second case with pleural involvement was being treated for tuberculosis.
In general, Co-trimoxazole (TMP-SMX), which can penetrate cerebrospinal fluid well is preferred as the first choice for treatment, and Amikacin, Imipenem, Minocycline, Ciprofloxacin being other second line agents. Combination with one or more drugs is preferable especially in disseminated disease with cerebral involvement,  or immunosuppressed states. Treatment must be continued for 12 months. ,, In both the cases treated at our hospital, long term combination therapy of Co-trimoxazole with other second line drugs was adopted.
These cases highlight the importance of including Nocardia as a differential diagnosis especially in immunosuppressed patients who present with abnormal MRI scan findings that mimic tuberculoma or neoplastic disease. Clinical and radiological features are not pathognomic for Nocardia infections, thus smear and culture remain the principal modes of diagnosis.
The course of Nocardia brain abscess is unpredictable and the patient's condition may deteriorate suddenly.  The mortality in patients with nocardial abscess is 3 times higher than in patients with brain abscesses caused by other bacteria. , Thus clinical awareness of this condition could expedite the diagnosis and treatment to reduce morbidity and mortality.
| Acknowledgements|| |
Dr. Arunaloke Chakrabarti, Professor and In-charge, Centre of Advance Research in Medical Mycology and WHO Collaborating Centre, Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]