STUDIES ON THE ROD-COCCUS LIFE-CYCLE OF RHODOCOCCUS-EQUI

In the present study all 19 Rhodococcus equi cultures isolated from ho rses and 19 of 22 R. equi cultures isolated from human patients displa yed a led-coccus life cycle after cultivation under defined growth con ditions. A bacillary growth could be observed after cultivation of the bacteria in fluid media for 4 h at 37 degrees C, a coccoid morphology after cultivation of the bacteria for 24 h either on sheep blood agar plates or in fluid media The different morphological features did not significantly influence the typability of the bacteria or the express ion of surface proteins including 15-17 kDa virulence proteins. Studie s on further surface characteristics revealed a relation between haema gglutinating properties, the surface hydrophobicity and adherence prop erties of the bacteria to HeLa cells. These properties seemed to be in fluenced by the cultivation conditions but not by the different morpho logical forms of the bacteria A haemagglutination reaction, a hydropho bic surface and an enhanced adherence to HeLa cells could be observed with coccoid bacteria after cultivation in fluid media for 24 h at 37 degrees C but not with coccoid bacteria harvested from sheep brood aga r plates or with bacillary bacteria after 4 h growth in fluid media. T his difference might possibly be caused by the degree of encapsulation of the bacteria after various cultivation conditions and a subsequent masking effect of the hydrophilic polysaccharide capsule of R equi.