Central nervous system melioidosis in the pediatric age group: review

Neuromelioidosis: A Single-Center Experience with Emphasis on Imaging

Introduction  Infection with Burkholderia pseudomallei , a gram-negative bacterium found in soil and surface water, is termed melioidosis and is commonly reported to occur in Southeast Asia and Northern Australia, where it is endemic. It is being increasingly reported in India, and transmission occurs through inhalation, inoculation, and ingestion. The neuroparenchyma, the adjacent soft tissue, and bone are known to be affected in both the acute and chronic disease forms. Involvement of these structures is rare but causes significant mortality and morbidity.

Material and Methods  Eighteen culture-proven cases of neuromelioidosis were identified between January 2008 and December 2019. The patients were retrospectively identified via search of the hospital’s electronic database.

Results  Cranial disease was in the form of parenchymal abscesses ( n = 4), cerebritis/encephalitis ( n = 5), and extradural ( n = 4) and dural disease ( n = 1). Acute myelitis ( n = 1) and spondylodiscitis ( n = 3) were seen in the spinal disease form. Neuroparenchymal involvement ranged from cerebritis/encephalitis to early and mature parenchymal abscesses. Extradural involvement was in the form of extradural abscesses and/or thick irregular enhancement in the extradural region. Early diagnosis and initiation of appropriate therapy had favorable outcomes in 15 out of 18 patients. Two patients with parenchymal abscesses and one with myelitis succumbed to the illness.

Conclusion  Neuromelioidosis is a rare manifestation of melioidosis with significant morbidity and mortality, necessitating a high index of clinical suspicion, especially if there has been travel to endemic regions. Imaging plays a key role in facilitating early diagnosis and initiation of therapy.

Cranial Melioidosis Presenting as Osteomyelitis and/or Extra-Axial Abscess: Literature Review

BACKGROUND

Central nervous system (CNS) melioidosis is rare. Clinical presentations depend on the region of endemicity. Despite treatment, neurologic disease has relatively high mortality rates. Less than 80 cases of CNS involvement have been reported.

METHODS

A literature review was performed by searching online databases for melioidosis presenting as osteomyelitis or scalp/extra-axial abscess (OSEAA). In addition, 3 similar cases managed at my institute have been presented.

RESULTS

Including this report of 3 cases, 20 additional cases have been reported. Of these, 12 cases (60%) were from India. The mean age of patients was 45.5 years (range, 29-74 years), and none were in the pediatric age group. Patients in the fifth to sixth decades were most frequently affected. The male to female ratio was 5.3:1. Eleven patients had predisposing factors. Fever, headache, and scalp swelling were the most common features. Five cases had history of previous melioid infection. Seven cases had systemic disease. Debridement was performed in 11 cases. The average intensive phase treatment duration was 4.6 weeks (range, 2-8 weeks) and 5.5 months (range, 3-12 months) for the maintenance phase. Mean follow-up duration was 13.5 months (range, 2 weeks-40 months). Two deaths (10%) were reported, and 1 case of residual frontal abscess had relapse.

CONCLUSIONS

Cranial melioidosis presenting as OSEAA is associated with good outcome, in contrast with other neurologic presentations. Intensive phase for at least 2-3 weeks followed by maintenance phase for 3-6 months is the standard treatment, similar to other melioid presentations. A high degree of suspicion and accurate identification of the organism is crucial. Patients need to be monitored for recurrences, both clinically and radiologically.

Central nervous system melioidosis: A systematic review of individual participant data of case reports and case series

BACKGROUND

Central nervous system (CNS) melioidosis is rare. However, delayed diagnosis and treatment could lead to fatality. To identify knowledge of CNS melioidosis, we systematically review case reports and case series.

METHODOLOGY/PRINCIPAL FINDINGS

We searched through PubMed, Web of Science and Thai-Journal Citation Index databases as well as Google Scholar with the last date on July 10, 2018. The diagnosis of CNS melioidosis had to be confirmed with culture, serology or polymerase chain reaction. We excluded the animal cases and the studies that the clinical data were not available. We identified 1170 relevant studies, while 70 studies with a total of 120 patients were analyzed. Ninety-three percent of patients were reported from the endemic area of melioidosis. Median age was 40 years (IQR 18-53), and 70% were men. A total of 60% had one or more risk factors for melioidosis. The median duration from clinical onset to diagnosis was ten days (IQR 5-25). Fever (82%), headache (54%), unilateral weakness (57%) and cranial nerve deficits (52%) are among the prominent presentation. Most patient (67%) had at least one extraneurological organ involvement. The CSF profile mostly showed mononuclear pleocytosis (64%), high protein (93%) and normal glucose (66%). The rim-enhancing pattern (78%) is the most frequent neuroimaging finding in encephalomyelitis and brain abscess patients. Both brainstem (34%) and frontal lobe (34%) are the most affected locations. Mortality rate was 20%.

CONCLUSIONS/SIGNIFICANCE

This study is the most extensive systematic review of case reports and case series of CNS melioidosis in all age groups. However, the results should be cautiously interpreted due to the missing data issue. The propensity of brainstem involvement which correlates with prominent cranial nerve deficits is the characteristic of CNS melioidosis especially encephalomyelitis type. The presenting features of fever and neurological deficits (especially cranial nerve palsies) along with the mononuclear CSF pleocytosis in a patient who lives in the endemic area and also has the risk factor for melioidosis should raise the CNS melioidosis as the differential diagnosis.

Burkholderia pseudomallei-loaded cells act as a Trojan horse to invade the brain during endotoxemia

Neurologic melioidosis occurs in both human and animals; however, the mechanism by which the pathogen Burkholderia pseudomallei invades the central nervous system (CNS) remains unclear. B. pseudomallei-loaded Ly6C cells have been suggested as a putative portal; however, during melioidosis, lipopolysaccharide (LPS) can drive disruption of the blood-brain barrier (BBB). This study aims to test whether the Trojan horse-like mechanism occurs during endotoxemia. The expression levels of cerebral cytokines, chemokines and cell adhesion molecules; the activation of astrocytes, microglia and endothelial cells; and the increased vascular permeability and brain-infiltrating leukocytes were evaluated using B. pseudomallei, B. thailandensis, B. cenocepacia and B. multivorans LPS-induced brains. Accordingly, different degrees of BBB damage in those brains with endotoxemia were established. The B. multivorans LPS-induced brain exhibited the highest levels of disruptive BBB according to the above mediators/indicators. Into these distinct groups of endotoxemic mice, B. pseudomallei-loaded Ly6C cells or free B. pseudomallei were adoptively transferred at equal bacterial concentrations (10³ CFU). The bacterial load and number of cases of meningeal neutrophil infiltration in the brains of animals treated with B. pseudomallei-loaded Ly6C cells were higher than those in brains induced by free B. pseudomallei in any of the endotoxemic groups. In particular, these results were reproducible in B. multivorans LPS-induced brains. We suggest that B. pseudomallei-loaded cells can act as a Trojan horse and are more effective than free B. pseudomallei in invading the CNS under septic or endotoxemic conditions even when there is a high degree of BBB disruption.