Nocardial brain abscess in an immunocompetent patient and review of literature
© The Author(s) 2016
Received: 30 October 2015
Accepted: 21 July 2016
Published: 18 August 2016
Nocardial brain abscesses are associated with significant morbidity and mortality rates. The optimal management remains unclear.
We report a case of 49-year-old woman presented with dizziness, progressive headache for 3 days, accompanied with left arm twitched for twice. The patient underwent a right parietal craniotomy for resection of the lesion. Gross total resection of the lesion was achieved. There were no new neurological deficits post-operatively, and no lesions was demonstrated on Gd-enhanced MRI images at six months follow-up.
After review of the literature and experience learned from our case, we suggest that craniotomy and surgical resection of the lesions, instead of aspiration, is a safe, efficacious treatment for the patient with nocardial brain abscesses. Long-term chemotherapy and follow-up is mandatory in all cases.
KeywordsBrain abscess nocardiosis Surgical treatment Magnetic resonance imaging
Nocardial brain abscesses are associated with significant morbidity and mortality rates. The optimal management remains unclear. The authors describe the case of an immunocompetent patient suffering from afebrile nocardial brain abscess in right parietal lobe after CT scan of brain and lungs, which was mistaken for a metastatic tumor of bronchioloalveolar carcinoma when the patient was admitted. Careful differential diagnosis and proper treatment are vital for a favorable prognosis.
History and presentation
The patient underwent a right parietal craniotomy for resection of the lesion. Gross total resection of the lesion was achieved. Yellow-green pus was found inside the lesion during operation and the sample was send to lab for bacterial and fungal culture. The operation time was 3 h and 15 min.
Hematoxylin-eosin staining confirmed brain abscess, and the pus bacterial and fungal culture confirmed Nocardia asteroids infection.
Nocardial brain abscess are relatively uncommon, accounting for 2 % of all abscesses . The published literature is limited, consisting largely of case reports involving three or fewer patients, and it is thus not possible to draw firm conclusions regarding the optimal surgical management of this condition. To date, there has only been one large clinical study, which suggested that craniotomy and excision is necessary in most cases of nocardial brain abscesses . Nocardial brain abscesses are associated with significant morbidity and mortality rates. We reviewed the surgical outcome of one patient treated with surgical resection combined with antibiotics postoperatively at a single institution. The diagnosis was made as a metastatic tumor when the patient was admitted according to her chest and brain CT scans. Our case shows the importance of early diagnosis and aggressive treatment of these lesions. Careful differential diagnosis and proper treatment are vital for a favorable prognosis. Despite their low incidence, we need to consider nocardial infection in the differential diagnosis of a cerebral lesion in order to obtain an early diagnosis and start treatment as soon as possible.
Like most brain lesions, the likelihood of successful management of nocardial brain abscess increases with early diagnosis. For this reason, and because a nocardial brain abscess can progress rapidly, a presumptive diagnosis is often necessary. Less than 10 % of nocardial infections originate in the CNS, it is more commonly encountered as a secondary lesion (as seen in our case). Subsequent hematogenous dissemination may lead to infection of almost any organ, with a particular predilection for the CNS . It often appears as a focal abscess, predominately supratentorially. The management of nocardial brain abscesses requires a high index of clinical suspicion, and early diagnosis is imperative.
The mortality rate of patients with these abscesses is more than three times higher than that of patients with other bacterial brain abscess. Although Nocardia is a rare cause of intracranial abscess, its mortality rate (31 %) is considerably greater than others (<10 %) . Prompt diagnosis followed by aggressive surgical management appear most likely to cure patients with cerebral nocardiosis. Diagnosis and treatment of nocardial brain abscesses continue to be challenging.
These infections usually occur in immunocompromised patients who have predisposing factors such as malignancy, diabetes mellitus, malnutrition and uremia. However, they are not necessarily associated with predisposing factors such as immunosuppresion, and there have been report of nocardial infections being observed in immunocompetent patients , and our case also show this lesion can occur in immunocompetent patient without fever. In our opinion, nocardial brain abscess is insidious infection, so the immune system may not work effectively enough to response the infection, as a result, no fever was seen in these patients.
Nocardial organisms are mostly isolated from plants and soil, and infection occurs most often as a result of inhalation or direct skin inoculation. Many case reports cite the earliest symptoms as a respiratory infection (i.e., with coughing and fever) [2, 5]. However, no fever and coughing was noted in our case when and before patient admitted. The brain, meninges, or spinal cord is often the site of secondary nocardial infection. The lungs are the most common primary sites of infection (73 % of patients). This distribution of infection is not unexpected, given that Nocardia are believed to first enter the body via the lungs or gastrointestinal tract before disseminating through the blood stream to the various organs. Frequently, the onset of a norcadial brain abscess is insidious, particularly in those individuals who are immunocompetent. As is the case with other brain abscesses, headaches seem to be the most common presenting symptom. Focal neurologic deficits occur depending on the location of the abscess.
Nocardial brain abscesses present as characteristic hyperenhanced multiloculated ring lesions. Perilesional edematous changes also might be present. It is sometimes difficult to differentiate a brain abscess from intracranial metastatic malignancy on regular MRI . However, diffusion weighted imaging (DWI) and apparent diffusion coeffient (ADC) map could be very helpful in the differentiate diagnosis, with brain abscess showing the characteristic homogeneously heperintense lesions on DWI and hypointense lesion on ADC. The restricted Brownian motion of water molecules in the organized purulent milieu of microorganisms, macromolecules and inflammatory cells contributes to the signal of restricted diffusion on DWI . Our patient displayed these imaging characteristics and clinical manifestation without fever, and she is an immunocompetent patient. As a result, we made a diagnosis as metastatic tumor when combined the clinical presentation and preoperative CT of lungs and MRI scans without DWI and ADC when patient admitted. And then, the diagnosis of brain abscess were made when DWI and ADC map were completed.
Our case shows the importance of early diagnosis and aggressive treatment of these lesions. Nocardial brain abscess may progress rapidly, lead to brain herniation, and become life threatening. Also, as learned from Lee’s experience , in which they made aspiration and biopsy first, and then the neurological symptoms deteriorated with progressive drowsy, so the craniotomy and excision of the lesion was performed to save the patient’s life. To prevent a delay in diagnosis and treatment, an aggressive therapeutic approach is required [7, 8]. Unlike other bacterial abscesses, craniotomy and excision of the entire abscess and wall are usually more effective than aspiration and drainage, particularly when the lesions have not responded to antibiotic therapy [1, 9] . Importantly, keep the abscess wall intact during surgical procedure is critical.
To treat a nocardial brain abscess, craniotomy with evacuation of the abscess, as well as collection of a specimen for culture to further assess drug sensitivity, are essential for successful treatment. Antibiotics is necessary and as adjunct therapy after surgery. Sulfonamides are the drug of choice, based on empirical data. Given the high rate of relapse and the characteristic resistance pattern, treatment should be aggressive and continued for months, with antibiotic treatment being adjusted according to the drug sensitivity test . A 12-month course of therapy is recommended for the treatment of nocardial brain abscesses. Trimethoprim-sulfamethoxazole (TMP-SMX), ceftriaxone, amikacin and minocycline are used for nocardiosis. TMP-SMX is currently accepted as the first-line treatment for nocardiosis . In our case, we gave ceftriaxone sodium for one month according to drug sensitive test of pus, and then gave TMP-SMX to the patient for one year after surgery, and the lesions in lungs were significantly diminished at six months follow-up after surgical procedure.
Diagnosis and treatment of nocardial brain abscess continue to challenge clinicians. It is important for the clinicians to be familiar with the characteristics of nocardial infections so that an early presumptive diagnosis can be made while awaiting confirmatory results of culture. We report a nocardial cerebral abscess mimicking a metastatic brain tumor. From the literature review and our experience, it is suggestive that craniotomy and surgical resection of the lesions, instead of aspiration, may be a safe and efficacious treatment for the patient with nocardial brain abscesses. Long-term chemotherapy and follow-up is mandatory in these cases. Prompt diagnosis followed by aggressive surgical management appear most likely to cure patients with these lesions.
apparent diffusion coefficient
Diffusion weighted imaging
fluid attenuated inversion recovery
magnetic resonance imaging
We thank John W. Chen from Massachusetts General Hospital for manuscript revision.
This study was supported by National Natural Science Foundation of China (81501116, to YZ), Gansu Province Science & Technology Program (1506RJZA228, to YZ) and Lanzhou City Science & Technology Program (2014-1-30, to YZ).
Availability of data and material
There is no new software, databases and raw data to be shared in this manuscript.
YP, YZ, QL carried out the neurosurgery and obtained the specimen. YZ, WZ, YJ and BH collected the data of the patient and drafted the manuscript. WZ and NW carried out the pathology experiments. YZ, QL, BH, NW and YP made follow-up of patient. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
The patient involved in this study consent to publication her individual person’s data (including individual details and images) in Chinese Neurosurgical Journal.
Ethics approval and consent to participate
This study was approved by the Ethics Committee of Lanzhou University Second Hospital (number: 20150270).
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