PHYLOGENETIC PLACEMENT AND CHARACTERIZATION OF A NEW ALPHA-2 PROTEOBACTERIUM ISOLATED FROM A PATIENT WITH SEPSIS

An alpha-2 proteobacterium, previously unknown as determined by its ph ylogenetic characteristics and the DNA sequence of its 16S rRNA gene, was isolated from a patient who presented an unusual clinical picture, including high remitting fever and multiorgan involvement, The bacter ium was detected in multiple plasma samples, obtained during the acute phase of the disease, after cocultivation in cell culture media, Elec tron microscopy of the organism showed a three-layer laminar cell wall and electron-dense granules within the cytoplasm, as well as a polar flagellum. By means of PCR followed by sequencing of amplified 16S rib osomal DNA fragments, the bacterium was found to differ from all speci es for which ribosomal sequence information is available. It is here p rovisionally named the Rasbo bacterium. At a subsequent relapse, the b acterium was identified in pericardial fluid both bq PCR/sequencing an d by direct electron microscopy. At a second relapse, it was again cul tured from plasma, After in vitro adaptation to solid media, the MICs of various antibiotics could be determined, A transient immunoglobulin RI (IgM) but no IgG response to the bacterium was found by an indirec t immunofluorescence test, as well as by an immobilization test during the acute phase of the disease.