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Volume 24, Number 2—February 2018


Yersinia pestis Survival and Replication in Potential Ameba Reservoir

David W. MarkmanComments to Author , Michael F. Antolin, Richard A. Bowen, William H. Wheat, Michael Woods, Mercedes Gonzalez-Juarrero, and Mary Jackson
Author affiliations: Colorado State University, Fort Collins, Colorado, USA (D.W. Markman, M.F. Antolin, R.A. Bowen, W.H. Wheat, M. Gonzalez-Juarrero, M. Jackson); Burrell College of Osteopathic Medicine, Las Cruces, New Mexico, USA (M. Woods)

Main Article


Properties and kinetics of 5 amebae species after experimental Yersinia pestis infection

Dormant state
Infection prevalence*

Infection intensity†

Intracellular survival‡
Intracellular replication
24 h

48 h
Mean, %
Mean, %
Mean, %
Mean, %
Acanthamoeba castellanii Cyst 33.63 5.21 4.22 0.61 0 0 0 0 Inconclusive§
A. lenticulata Cyst 51.66 3.17 6.41 0.43 10 11.55 0 0 No
A. polyphaga Cyst 49.08 5.41 5.36 0.37 31.66 22.04 0 0 No
Dictyostelium discoideum Spore 39.24 3.13 3.57 0.97 270 19.92 226.67 22.71 Yes
Vermamoeba vermiformis Cyst 29.61 3.4 1.84 0.13 10 9.66 0 0 No

*Mean percentage of amebae containing >1 intracellular bacterium.
†Mean no. of intracellular bacteria per individual infected ameba.
‡Mean no. of surviving intracellular bacteria (relative to control) in experiments with 1 and 4 h of antibiotic drug exposure.
§We observed no replication in the intraameba replication assay, which we used to count intra-ameba bacterial colony-forming units before and after co-culture. However, we observed probable but nondefinitive mitotic bacterial replication in the TEM micrographs (Figure 4, panel A).

Main Article