Septicemia caused by tick-borne bacterial pathogen Candidatus Neoehrlichia mikurensis

Abstract

We have repeatedly detected Candidatus Neoehrlichia mikurensis, a bacterium first described in Rattus norvegicus rats and Ixodes ovatus ticks in Japan in 2004 in the blood of a 61-year-old man with signs of septicemia by 16S rRNA and groEL gene PCR. After 6 weeks of therapy with doxycycline and rifampin, the patient recovered.

Figure 1

Polyacrylamide gel electrophoresis (SDS-PAGE) analysis of broad range 16S rRNA gene PCR products obtained from blood samples. Lane 1, marker, 100 bp DNA ladder (Roche DNA Marker XIV); lane 2, positive control, Escherichia coli; following lanes, PCR products obtained from blood specimens arranged by date of collection. For each specimen PCR products are shown obtained with undiluted (0) and 5×-diluted (5) DNA extracts. The 2 last negative samples are not shown.

Figure 2

A) Phylogenetic tree based on the 16S rRNA gene sequences of Candidatus Neoehrlichia mikurensis GQ501090.2 (our patient’s isolate, herein termed Zurich and indicated in boldface) and related organisms. The number at nodes indicates percentages of bootstrap support based on 10,000 replicates. Scale bar indicates 0.02 substitutions per nucleotide position. B) Phylogenetic tree based on the groEL sequences. Scale bars indicate 0.05 substitutions per nucleotide position.