Walsh & Hoyt: Description

Rickettsiae are pleomorphic coccobacilli that are 1.02.0 micrometers long and 0.3 micrometers wide. They resemble gram-negative bacilli in both structure and physiology. They multiply by binary fission, contain both deoxyribonucleic acid (DNA) and RNA, and have both synthetic and energy-producing enzyme systems. In addition, some of the rickettsiae contain endotoxins. Rickettsiae are difficult to stain with ordinary bacterial stains, but they stain well with acridine orange and under immunofluorescence