ISOLATION OF AN ACANTHAMOEBA STRAIN WITH INTRACELLULAR BURKHOLDERIA-PICKETTII INFECTION

Burkholderia pickettii is a facultative pathogen that has been isolate d from patient sources and environmental sources including respiratory therapy solutions, deionized water and aqueous disinfectants. The org anism has been associated with septicemia and respiratory tract infect ions. In our investigation, Burkholderia pickettii (biovar 2) was for the first time isolated from Acanthamoeba sp. (group II), a free livin g amoeba species recovered from the wet area of a physiotherapy unit. Pathogenic strains of acanthamoebae may cause amoebic-encephalitis (AE ) and keratitis. Light and electron microscopic examinations showed th at in a first step, the bacteria were phagocytised by the amoebae. In contrast to Enterobacter cloacae and Escherichia coli that were used a s food organisms and digested within food vacuoles, Burkholderia picke ttii caused the amoebae to develop large vacuoles filled with complete ly intact and motile bacteria. 3-5 days after infection, Pseudomonas p ickettii had multiplied within the enlarging parasitophorous vacuoles. Ultrastructural changes in the host cells occurred and the amoebae fi nally underwent rupture or lysis. In cocultivation assays we could not only reinfect the original host amoeba but Acanthamoeba strains from other habitats could successfully be infected with Burkholderia picket tii as well.