RESUMO
OBJECTIVE: Human Granulocytic Anaplasmosis (HGA) is an emerging disease caused by the gram-negative bacterium Anaplasma phagocytophilum which is transmitted by ticks of the genus Ixodes ricinus. For molecular detection of the pathogen by PCR, a conserved portion of the groEL gene within the groESL operon is frequently used as a target. A single G/A polymorphism in this region allows to discriminate between two genotypes, groEL-G and groEL-A. METHODS: Total DNA from peripheral blood samples of two HGA patients was analysed by RealTime PCR, employing a protocol designed for genotyping groEL-G- and groEL-A variants of A. phagocytophilum. RESULTS: We confirmed two clinical cases of HGA by PCR; in one patient, and for the first time in a human host, the groEL-A variant was detected, in the other case the pathogen was recognised as the groEL-G variant, up to now representing the only genotype reported in man. CONCLUSIONS: It is documented that HGA infections can be caused by two A. phagocytophilum groEL genotypes. At present, the preference of the A. phagocytophilum groEL-G genotype in humans remains unclear, as we describe the first patient with HGA caused by the groEL-A variant. For a conclusive interpretation, more data from HGA patients will be required.