This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mason, R. A. Search for Related Content PubMed PubMed Citation Articles by Mason, R. A.

 Previous Article  |  Next Article 

J Bacteriol. 1970 July; 103(1): 184-190
Copyright © 1970 American Society for Microbiology. All Rights Reserved.

Propagation and Growth Cycle of Rickettsia quintana in a New Liquid Medium

¹ Public Health Service, National Institutes of Health, Division of Biologics Standards, Laboratory of Virology and Rickettsiology, Bethesda, Maryland 20014

ABSTRACT

The growth cycle of Rickettsia quintana was studied for the first time in liquid culture. Growth of the microorganism in a transparent broth medium was made possible by the finding that fetal calf serum (FCS), but not calf serum (CS), satisfied the requirement of R. quintana (Fuller strain) for red blood cell lysate. The three constituents of the medium, other than FCS, were autoclavable. The growth cycle was characterized by a lag phase of approximately 24 hr, an exponential growth phase of 72 hr, and a doubling time of approximately 4.5 hr. In FCS medium, titers increased 10⁵-fold over starting titers and reached a peak after 5 days of greater than 10⁸ colony-forming-units (CFU)/ml. Optical density readings at 520 nm (OD₅₂₀) served as useful estimates of the titers only during the last 30 hr of exponential growth. Before this time, titers were below 3 x 10⁷ CFU/ml and could not be detected at OD₅₂₀. The growth-promoting activity of FCS appeared to be a normal serum component widely distributed among fetal calves. FCS from five commercial suppliers supported growth of R. quintana. The active factor(s) was: (i) non-dialyzable, (ii) resistant to heating at 56 C for 30 min, and (iii) partially inactivated at 100 C in 2 min and completely lost at 100 C in 10 min. The results emphasize the presence of erythrocyte and serum factors other than hemoglobin which stimulate the growth of R. quintana.