Trojan horse L-selectin monocytes: A portal of Burkholderia pseudomallei entry into the brain (Editorial)

Abstract

Melioidosis is caused by the bacterium Burkholderia pseudomallei and infections can be severe with high mortality. It is estimated that around 165,000 cases of melioidosis occur each year with an annual death toll of some 89,000.1 The bacterium is likely to be endemic to 77 countries and is most prevalent in south-east Asia and northern Australia. Infection with the bacterium does not always lead to melioidosis as many people can be seropositive without having reported symptoms2 or in some cases melioidosis can arise after considerable latency even decades after exposure.2,3 The bacterium is present in soil and water and can be inhaled through dust that may be raised during storms, or can enter the body via percutaneous inoculation. Infection is particularly prevalent during the wet season and can lead to septicaemia and affect numerous different organs as it spreads haematogenously. Symptoms range from skin and nasal infections to systemic presentations with pneumonia and septic shock. In a minority of cases it can infect the brain where it causes neurological melioidosis and brainstem encephalitis—this form of the disease is particularly difficult to treat as it requires long term antibiotic administration. Neurological melioidiosis presents with brainstem encephalitis, brain abscesses, fluctuating consciousness, brainstem signs, and there is a recognized syndrome of brainstem and spinal cord involvement. Neurological melioidosis leads to death in ∼25 % of the cases despite treatment and can have very serious sequelae such as residual paralysis and ataxia.4