An alpha-2 proteobacterium, previously unknown as determined by its phylogenetic 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 bacterium was detected in multiple plasma samples, obtained during the acute phase of the disease, after cocultivation in cell culture media. Electron 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 ribosomal DNA fragments, the bacterium was found to differ from all species for which ribosomal sequence information is available. It is here provisionally named the Rasbo bacterium. At a subsequent relapse, the bacterium was identified in pericardial fluid both by PCR/sequencing and by direct electron microscopy. At a second relapse, it was again cultured from plasma. After in vitro adaptation to solid media, the MICs of various antibiotics could be determined. A transient immunoglobulin M (IgM) but no IgG response to the bacterium was found by an indirect immunofluorescence test, as well as by an immobilization test during the acute phase of the disease.
MATERIALS AND METHODSCase report. A previously healthy 33-year-old man was admitted to the hospital 8 days after the onset of respiratory symptoms and severe myalgia followed by the development of fever. One of the most conspicuous clinical features was remitting fever continuing for 3 months and with extreme quotidian amplitude, with peak values reaching 42.3°C. Severe symptoms involving serous membranes and visceral organs gradually developed, i.e., profuse diarrhea and pericardial, pleural, and peritoneal effusions, as well as signs of myocardial, hepatic, and splenic involvement. Intensive care was required for several weeks. An extensive search for a microbial cause by conventional methods failed to demonstrate an infectious agent, and broad-range testing for systemic, endocrine, and malignant diseases resulted in negative findings. Presumptive treatment was given with a great number of antibacterial drugs, with no clear response to any specific drug. After 3 months, when antimicrobial chemotherapy had been discontinued due to suspected side effects, the fever and other symptoms gradually disappeared and the patient could leave the hospital. In the meantime, an infectious agent from the patient's plasma had adapted to in vitro growth on artificial media (see below). Two months after the patient was discharged from the hospital a relapse occurred, and the patient was readmitted with chest symptoms and a temperature above 40°C. Seven hundred milliliters of pericardial fluid was evacuated. The patient recovered within 2 weeks on doxycycline treatment that was continued until a second relapse occurred 7 months later. Compliance was checked by determination of the doxycycline concentration in serum on admission at the second relapse. At this time...