Table 1.

Characteristics of isolates of strain 24067 used in this study

IsolateLaboratoryaClearance halob at 9 daysClearance halob at 14 daysCapsule thickness/cell diametercPigment formation onl-dopa platesDoubling timed at 37°C (h)Log10 of CFUs/organe
LungLiver
24067-AA. Casadevall0.037 ± 0.0400.631 ± 0.0930.347 ± 0.140Yes3.944.466 ± 0.3635.843 ± 0.317
5BA. CasadevallNot detected0.070 ± 0.0760.229 ± 0.099Yes3.613.768 ± 0.3675.174 ± 0.565
29AA. Casadevall0.142 ± 0.0951.061 ± 0.1090.267 ± 0.130Yes3.843.199 ± 0.2674.901 ± 0.372
29BA. Casadevall0.195 ± 0.1841.084 ± 0.1150.399 ± 0.190Yes3.434.093 ± 0.4945.117 ± 0.387
24067-BM. Scharff0.342 ± 0.0420.780 ± 0.0560.236 ± 0.104Yes3.677.180 ± 0.1973.563 ± 0.854
24067-EG. Huffnagle0.258 ± 0.0640.671 ± 0.0510.195 ± 0.074Yes3.026.997 ± 0.6213.539 ± 0.729
24067-GJ. Murphy0.015 ± 0.0200.445 ± 0.0420.122 ± 0.050Yes3.093.836 ± 1.5343.732 ± 1.563
  • a The laboratory from which the strain was obtained for this study. For additional details of the origin and handling of these strains, see Franzot et al. (7).

  • b Clearance halo is measured as the thickness of the halo divided by the colony diameter. The numbers are averages ± standard deviations (n = 30). At day 9 clearance was significant at P < 0.05 for all pairwise comparisons except 24067-A versus 5B or 24067-G and 5B versus 24067-G (Bonferroni t test). At day 14, clearance was significant at P < 0.05 for all pairwise comparisons except 29A versus 29B and 24067-A versus 24067-E (Bonferroni t test).

  • c Capsule and cell measurements were done when cultures had a density of ∼108 cells/ml. The numbers are averages ± standard deviations (n = 20). Statistically significant differences were seen for the following pairwise comparisons: 29B versus 5B, 29A, 24067-B, -E, and -G; 24067-A versus 24067-G; and 24067-A versus 5B (P < 0.05; Bonferroni t test).

  • d Doubling time was calculated from the logarithmic phase growth rate by curve fitting the CFU data and applying the formula N = N0 × e(a × t) ( SigmaPlot version 2.03; Jandel Scientific, San Rafael, Calif.) with t defined as time , N as the CFU at t, N0 as the initial CFU, and a as the growth factor of the isolate. Errors are the standard errors of the means of the calculated a values.

  • e Infection with isolates 24067-A, 5B, 29A, and 29B was done via i.p. injection of C. neoformans. Isolates 24067-B, -E, and -G were administered via i.t. infection. Statistical significance within the groups of infections was seen only for pairwise comparison between lungs infected with 24067-B or -E versus -G (P < 0.05; Bonferroni t test).