Roseomonassp. Isolated from Ticks, China

Roseomonas sp. Isolated from Ticks, ChinaTo the Editor: Roseomonas, which produces pink colonies, is a newly described genus of gram-negative bacteria (1).Human infections with Roseomonas spp.have been reported in the past decade, mostly in immunocompromised persons with underlying diseases such as acute leukemia, cancer, and rheumatoid arthritis (2-5).A healthy woman was reported to be infected by R. gilardii after being bitten by a spider (6), which indicated possible transmission by an arthropod.As a part of an investigation of tickborne diseases, we collected actively questing and feeding ticks in Xinjiang Autonomous Region, People's Republic of China, in the summers of 2007 and 2008 (7).Ticks were washed in 75% ethanol, 30% hydrogen peroxide, and sterile distilled water.Five ticks of the same species, sex, and developmental stage were pooled and ground in 1 mL of saline.A 0.1-mL suspension was placed on cysteine heart agar plates containing chocolate and 9% sheep blood (Becton Dickinson Microbiology Systems, Cockeysville, MD, USA) and supplemented with colistin, amphotericin, lincomycin, trimethoprim, and ampicillin.Eggs laid by engorged female ticks were collected and kept at room temperature.Fourteen days after hatching, larval ticks were processed as a batch by using the same methods described above.After 2-3 days of incubation at 37°C, pink colonies were observed in 9 cultures, 8 of which originated from engorged female Dermacentor nuttalli ticks.The other culture originated from larval ticks, the progeny of an engorged female D. nuttalli tick.Colonies were pinpoint, pale pink, shiny, raised, and mucoid.The pink color of the colonies became pronounced when the bacteria were transferred onto