[The effect of some antibiotics on multiplication of Coxiella burneti in the embryonated egg (author's transl)].

In chick embryos 7 days after cultivation, the effect of chloramphenicol, streptomycin, tylosin (0.5 to 32 mg/egg), and of penicillin (100 to 10000 IE/egg) on the process of replication of C.b. in the yolk sac was examined. The ELD50 and the EID50 were examined according to REED and MUENCH. The demonstration of coxiellae was performed microscopically. The results of the examinations are summarized in fig. 1 to 3. In infected untreated controls, the titres of the ELD50 were found at about 10(4) and those of the EID50 at 10(7). The best inhibition was obtained by means of chloramphenicol. In this case, neither a letality of embryos nor an infectivity of eggs was demonstrable by administration of 16 mg/egg. Streptomycin had a similar effect on the letality of embryos like chloramphenicol, but coxiellae were still microscopically demonstrable at doses of 16 and 32 mg/egg. A smaller effect had tylosin so that even after an administration of 32 mg/egg, a minimal letality of embryos and a minimal infectivity of eggs remained. Almost no inhibition was obtained by means of penicillin. Even at 10000 IE/egg, the letality of embryos was diminished only by 1 log 10 and the infectivity of eggs by about 3 log 10. After application of chloramphenicol, streptomycin, and tylosin, the embryos in infected eggs died regularly 1 to 2 days later than those in untreated infected controls with the same titres. Using penicillin, this effect could not be observed.