Leptospiral Colonial Morphology

Abstract

Stalheim , O. H. V. (University of Wisconsin, Madison) and J. B. Wilson . Leptospiral colonial morphology. J. Bacteriol. 86: 482–489. 1963.—A sequence of apparent colonial types was observed with colonies of Leptospira pomona, L. canicola, L. icterohaemorrhagiae , and L. grippotyphosa in agar medium. Although some colonies of these serotypes had a different appearance initially, they eventually developed the mature or final appearance characteristic of the serotype. Colonies of freshly isolated, virulent cultures of L. pomona, L. canicola , and L. icterohaemorrhagiae were similar in appearance to colonies of avirulent strains of the same serotype. Additional studies of three stable and distinct colonial types of a laboratory strain of L. autumnalis revealed no differences in antigenicity, catalase activity, or mouse infectivity; however, differences in susceptibility to lysis by oleic acid were found. Although the colonial variants were stable during several in vitro variations, including growth in the presence of homologous antiserum and mutation to growth in a chemically characterized medium, rapid dissociation in vivo was found.

VIRULENCE-LINKED COLONIAL AND MORPHOLOGICAL VARIATION IN LEPTOSPIRA

“…Although colonial variation in leptospires has been described by Stalheim and Wilson (1963), and although the straight morphological variant has been noted (Simpson and White, 1964), the association of morphology with colonial forms is a new observation. A reasonable explanation would be that the relatively nonmotile straight leptospires tend to proliferate locally, whereas the more motile hooked leptospires travel further in the medium, and produce larger colonies.…”

Leptospiral Selection, Growth, and Virulence in Synthetic Medium

“…When evidence of growth appeared, 3, 5, or 10 ml was added to 10 ml of synthetic medium containing different concentrations of Tween 80 (0.002, 0.005, 0.007, 0.02, and 0.04%). Observations of the rate and amount of growth were recorded, and the agglutinability of the leptospires was determined as previously described (23,26).…”

“…Cultures of derived strains of L. pomona were incubated at 29 C with shaking [110 strokes per min with a 1-inch (2.54-cm) excursion] in Erlenmeyer flasks (1 liter) containing 500 ml of TSM modified by increasing the concentration of Tween 80 to 0.06% (MTSM). The amount of growth was estimated nephelometrically until it was maximal; then the bacterial density was determined by microscopic counts (23).…”

Surface colonies of Leptospira interrogans

“…Larson et al (13) demonstrated that leptospiral colonies were derived from the growth of single cells. It was observed that a sequential change in colonial morphology may occur as the colonies mature (16) and that colonial heterogeneity exists in some serovars of Leptospira (14,16). Studies of three stable and distinct colonial forms of serovar autumnalis provided evidence that no differences existed in their antigenicity or virulence (16).…”

“…It was observed that a sequential change in colonial morphology may occur as the colonies mature (16) and that colonial heterogeneity exists in some serovars of Leptospira (14,16). Studies of three stable and distinct colonial forms of serovar autumnalis provided evidence that no differences existed in their antigenicity or virulence (16). Faine and Van der Hoeden (7) reported virulence-linked morphological variation in serovar icterohaemorrhagiae.…”