Neurological Melioidosis Presenting as Rhombencephalitis, Optic Neuritis, and Scalp Abscess with Meningitis: A Case Series from Southern India
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.314590
Source of Support: None, Conflict of Interest: None
Keywords: Meningitis, neurological melioidosis, optic neuritis, rhombencephalitis, scalp abscessKey Message: Neurological meliodosis has varied manifestations and is likely under recognized in endemic countries. Nervous system involvement is usually by direct spread, but there are other potential mechanisms. Treatment involves an intensive and eradication phase with antibiotics.
Melioidosis, caused by the gram negative bacteria, Burkholderia pseudomallei, a soil saprophyte, is well-documented in South East Asia and northern Australia, where it is found to occur during and after the wet season. There is evidence to suggest that it may be endemic to the Indian sub-continent as well. Melioidosis has a wide range of presentations, varying from an acute fulminant septic illness to chronic infection. Site of infection, is usually pulmonary, followed by genitourinary, and skin. Neurological involvement is rare.,,, We present 3 patients with melioidosis and neurological manifestations.
An 18-year old male student presented with fever for 4 days. This was followed by rapidly progressive neurological symptoms of drooling of saliva from the left angle of the mouth and inability to close the left eye, swaying to either side, dysphagia, and binocular horizontal diplopia. At admission, he was conscious and oriented, with dysarthric speech, normal fundi, left gaze palsy, upbeat nystagmus, left facial sensory loss, bilateral lower motor neuron facial palsy, absent gag and poor palatal movements. Cerebellar signs were positive bilaterally and meningeal signs were present. He developed 2 seizures on the day of admission and became hypoxic. He was intubated and shifted to the ICU. His complete blood count showed: Hemoglobin 14.7 gm%, WBC 15300/mm3 (neutrophils 81%, lymphocytes 10%, monocytes 9%) Platelets 264,000/mm3, ESR 45. CT brain showed ill-defined hypodensities in the cerebellum, cerebellar peduncles and brainstem. MRI brain showed patchy T2 and FLAIR hyperintense lesions in the brainstem, middle cerebellar peduncles, and bilateral posterior limbs of internal capsule, in addition to few subcortical lesions [Figure 1]. Post-contrast enhancement was seen in the brainstem lesions, along the trigeminal nerves, facial and abducens nuclei. CSF showed 520 cells/mm3 (80% neutrophils), protein 58 mg/dl glucose 87 mg/dl. AFB stain and culture for bacteria including for mycobacterium tuberculosis (MTB) were negative. CSF PCR for MTB and the following viruses were found to be negative: Herpes simplex, Japanese encephalitis, and Ebstein barr virus. He was started on IV ceftriaxone, ampicillin in meningitic dose, and acyclovir, along with anti-epileptics. As the patient showed no clinical response to treatment, vancomycin and doxycycline were added for possible ceftriaxone resistant pneumococcal meningitis and scrub typhus respectively. Serology for leptospira and scrub typhus were negative. Repeat CSF performed 1 week later showed a further increase in cells to 980 cells/mm3 with neutrophilic predominance. Gram stain showed few gram negative bacilli, and Active Melioidosis Detect-Lateral Flow Assay (AMD-LFA) was positive in the repeat CSF sample. He was started on high dose IV meropenem and trimethoprim-sulphamethoxazole. Despite this, he did not improve and succumbed to his illness. CSF culture grew Burkholderia pseudomallei.
A 38-year old lady teacher with no pre-morbidities or antecedent illness presented with acute onset, painless loss of vision in the left eye. On examination, the right eye had a vision of 6/6 unaided, the left eye had no perception of light. Relative afferent pupillary defect was present in the left eye, bilateral fundi showed blurred disc margins. No other deficits were noted, meningeal signs were absent. Initial blood counts showed a neutrophilic leukocytosis (TLC 17600cells/mm3, Neutrophils 90.6%, Lymphocytes 4.2%, Monocytes 5%). MRI brain, orbit, and spine with contrast were normal, with no evidence of enhancement of the optic nerves. VEPs showed no recordable waves on the left, right was prolonged. SSEP and BAER were normal. CSF examination including oligoclonal bands was normal. Anti-aquaporin 4, anti-MOG antibodies, autoimmune and vasculitic profile were negative. She was treated with 5 days of intravenous methylprednisolone followed by short course oral steroids She developed fever with non-productive cough while on steroids. Contrast enhanced CT thorax showed consolidation in the right posterobasal segment of lung [Figure 2]. Blood culture grew B. pseudomallei, She was started on IV meropenem and oral co-trimoxazole. Induced sputum culture did not show any growth. Patient's visual acuity improved to 6/12 at discharge and subsequently to 6/6 at three months, with no recurrences till the last follow-up.
54-year-old male agriculturist with poorly controlled diabetes mellitus, presented with fever, and frontal headache associated with a swelling over the scalp for 15 days. On examination, bilateral papilloedema and neck stiffness were noted; systemic examination was unremarkable. A boggy swelling was noted over the scalp, which was tender and warm. Routine investigations revealed anemia with elevated ESR. CECT brain showed meningeal enhancement, subdural collection along the left fronto-parietal convexity causing mass effect, along with a subgaleal collection [Figure 3]. Patient underwent incision and drainage of scalp abscess. Pus culture grew B. pseudomallei. He was started on intravenous meropenem for 3 weeks along with trimethoprim-sulphamethoxazole for a duration of 6 months. Repeat CT showed resolution of the subdural collection and mass effect, with no abnormal meningeal enhancement. The patient recovered completely with no neurological sequelae.
The spectrum of nervous system involvement in melioidosis is protean and includes subdural or extradural collections, micro or macro brain abscesses, cranial or spinal osteomyelitis,,, leptomeningitis, meningonencephalitis,, brainstem encephalitis with multiple cranial nerve palsies,, myelitis,, Guillian-Barre syndrome,, and dural venous sinus thrombosis.,, Melioidosis is acquired by inhalation, ingestion or inoculation, and most individuals have risk factors such as diabetes mellitus, heavy alcohol use, chronic pulmonary diseases, and chronic renal disease. CNS involvement could occur via direct seeding or exotoxin mediated injury. Direct seeding may result from hematogenous spread or via intranasal inoculation, and spread along the olfactory and trigeminal nerves. Direct invasion of the nervous system has been demonstrated in neurological melioidosis. However, there have been cases described wherein CSF cultures are negative, and the CSF picture raise the possibility of other mechanisms such as toxin mediated injury. B. pseudomallei produces 2 exotoxins, which when injected into experimental animals produce spinal cord and brainstem involvement. Another possible mechanism would be autoimmune, via molecular mimicry, and this has been postulated in Guillian Barre syndrome presenting in the context of systemic melioidosis.
Our first case presented with rhomb-encephalitis, which etiologically, can be broadly classified into infectious, auto-immune and paraneoplastic causes. In view of the acute history, association with fever and CSF findings, an infective etiology was considered. Infections known to cause rhomb-encephalitis include Listeria monocytogenes, Enterovirus 71, Japanese encephalitis and other arboviruses, Herpes virus; and rarely tuberculosis, brucellosis, borreliosis, and melioidosis. Empiric antibiotic therapy did not cover for meliodosis, and it was only later that targeted antibiotic therapy was initiated. In this patient direct spread of B. pseudomallei into the nervous system likely occurred as evidenced by CSF culture positivity. In neurological melioidosis, MRI findings include both intra-axial and extra-axial abnormalities. Rim enhancing micro-abscesses with nodular and tubular morphology involving the infra and supra tentorial compartment and the spinal cord, with a predilection for white matter tracts have been described. Enhancement and thickening of cranial nerves, particularly the trigeminal nerve, has been observed.
The second case is unique, it is the first observation of an association between optic neuritis and melioidosis. The common causes for optic neuritis were not identified, and although a coincidental occurrence of these 2 conditions cannot be ruled out. In this patient there was no evidence to suggest direct involvement of the CNS, and hence a possibility of either exotoxin induced demyelination or immune mediated inflammatory demyelination are plausible. The focus of infection was in the lungs, and was almost certainly acquired in the community. Meliodosis has not been described as a hospital acquired infection. The patient likely had a chronic infection in the lung, latent at the time of presentation, which may have been activated by the use of steroids. Latent infections and relapses from previous foci of infection are known to occur. We hypothesize that optic neuritis in this case may have occurred as an immune mediated phenomena. The rapidity of visual improvement would not be compatible with a toxin induced demyelination. A similar mechanism for optic neuritis has been proposed in other bacterial infections. The third case is a more classic presentation with a suppurative infection over the scalp followed by abscess formation and subsequent intracranial spread, in an immune compromised individual.
Melioidosis has been recognized from different regions of India, however reports are largely confined to a few centers and it is likely under recognized. Treatment involves an initial intensive phase for 10–14 days with intravenous ceftazidime or meropenem. In neurological melioidosis, meropenem is preferred and the duration may be extended to ≥4-8 weeks. Eradication therapy should last for ≥3 months, and is initiated at the end of the intensive phase with trimethoprim–sulfamethoxazole. In neurological melioidosis, eradication phase may be initiated along with intensive phase and continued for longer (≥6 month). Through this case series we hope to improve the awareness of melioidosis among the neurological community, and encourage clinicians to consider this infection as a diagnostic possibility in the appropriate clinical setting.
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[Figure 1], [Figure 2], [Figure 3]