Identification of a granulocytotropic Ehrlichia species as the etiologic agent of human disease

Abstract

Six patients from northern Minnesota and Wisconsin with a febrile illness accompanied by granulocytic cytoplasmic morulae suggestive of ehrlichial infection were identified. Two patients died, and splenic granulocytes of one patient contained cytoplasmic vacuoles with organisms ultrastructurally characteristic of ehrlichiae. From one patient, a 1.5-kb DNA product was amplified by PCR with universal eubacterial primers of 16S rDNA. Analysis of the nucleotide sequence of the amplified product revealed 99.9 and 99.8% similarities with E. phagocytophila and E. equi, respectively, neither of which has previously been known to infect humans. From the variable regions of the determined sequence, a forward primer specific for three organisms (human granulocytic ehrlichia, E. phagocytophila, and E. equi) and a reverse primer for these ehrlichiae and E. platys were designed. By nested PCR with amplification by the universal primers and then reamplification with the specific primers described above, the expected 919-bp product was generated from the blood of the index patient and three additional patients. Blood from these four patients and two more patients with granulocytic morulae contained DNA which was amplified by nested PCR involving a combination of a universal primer and the human granulocytic ehrlichia-E. phagocytophila-E. equi-E. platys group-specific primer. This apparently vector-borne human granulocytic ehrlichia has only 92.5% 16S rDNA homology with E. chaffeensis. Nested PCR with group-specific primers did not amplify E. chaffeensis DNA, and E. chalfeensis-specific primers did not amplify DNAs of the human granulocytic ehrlichia. Thus, six patients were shown to be infected by an Ehrlichia species never previously reported to infect humans.

Then and now: use of 16S rDNA gene sequencing for bacterial identification and discovery of novel bacteria in clinical microbiology laboratories

“…In 2003, the genome sequences of two T. whipplei strains were completed [101,102], marking another milestone in medical history. Similar successes were seen in the context of bacillary angiomatosis (caused by Bartonella henselae and Bartonella quintana) [103,104] and human ehrlichiosis (caused by bacteria of the genera Ehrlichia and Anaplasma) [105][106][107].…”

A serological and clinical follow‐up in horses with confirmed equine granulocytic ehrlichiosis

“…Based on 16s rFWA gene sequences, an identical Ehrlichia sp. has also been demonstrated in man, horses and dogs in the USA (Chen et al 1994;Greig et al 1996;Madigan et al 1996) and recently in a human subject in Europe (Petrovec et al 1997). Tick exposure, which varies between biotopes (Jaensson 1991), is probably the most important factor influencing the prevalence of EGE.…”

Anaplasma phagocytophilumPSGL-1-independent infection does not require Syk and leads to less efficient AnkA delivery

“…This rickettsial pathogen is a member of the family Anaplasmataceae, which includes other obligate intracellular bacteria of the genera Anaplasma, Ehrlichia, Neorickettsia and Wolbachia (Dumler et al 2001). Since description of the first case in 1994 (Chen et al, 1994), HGA has been increasingly recognized in the USA, Europe and Asia. HGA is a potentially fatal systemic disease, the clinical manifestations of which include fever, headache, myalgia, leucopenia, thrombocytopenia and elevated levels of serum hepatic aminotransferases.…”