O. Cirioni et al., Inhibition of growth of Pneumocystis carinii by lactoferrins alone and in combination with pyrimethamine, clarithromycin and minocycline, J ANTIMICRO, 46(4), 2000, pp. 577-582
The in vitro activity of lactoferrins alone and in combination with clarith
romycin, minocycline and pyrimethamine was investigated against three clini
cal isolates of Pneumocystis carinii. Susceptibility was tested by inoculat
ing isolates on to cell monolayers and determining the parasite count after
72 h incubation at 37 degreesC. The culture medium was supplemented with s
erial dilutions of each agent. At 20 mg/L, bovine lactoferrin, the most act
ive agent, suppressed the growth of cystic and trophic forms by >60%. Human
lactoferrin, at the same concentration, suppressed the growth of cystic an
d trophic forms by >50%. Lactoferrins at 20 mg/L combined with clarithromyc
in 4 mg/L had high anti-P. carinii activity, with a >90% decrease in cystic
and trophic form counts. Our study suggests that lactoferrins may inhibit
P. carinii growth in vitro and act synergically with other clinically used
compounds. These findings lend experimental support to the use of iron-chel
ating agents in the therapy of pneumocystis infections.