Comparison of the ultrastructure of small dense forms of chlamydiae and Coxiella burnetii.

In the course of passaging of Coxiella burnetii (C.b.) in Alveonasus lahorensis ticks, the haemocytes contained cell forms with electrondense cytoplasm, intracytoplasmic lamellar membranes, and a peculiar limiting membrane--25 to 30 nm thick "envelope complex".

Sensitivity to macrolide antibiotics and lincomycin in Francisella tularensis holarctica.

Among the 345 F. tularensis holarctica strains isolated in Europe, Asia and North America, two variants were found: one sensitive and the other resistant to erythromycin, oleandomycin and lincomycin. These characteristics were not associated with virulence, antigenicity, biochemical activity or source of isolation and displayed high stability in passages in laboratory animals or multiple passages in culture media.

[Sensitivity of the causative agent of tularemia to antibiotics].

Sensitivity of the tularemia causative agent of different geographical races to antibiotics such as streptomycin, tetracycline, gentamicin, rifampicin (20 strains), ampicillin, polymyxin M, erythromycin, oleandomycin (361 strains) and lincomycin (294 strains) was studied. High sensitivity of the tularemi a microbe to streptomycin, tetracycline, rifampicin (MIC of 10 gamma/ml), gentamicin (MIC of 1 gamma/ml) and resistance to 50 gamma of ampicillin and 1000 gamma/ml of polymyxin M were found. Combined use of 50 gamma of ampicillin and 100 gamma/ml of polymyxin M added to the nutrient medium for growth inhibition of the foreign flora on isolation of the tularemia causative agent from the infected material including stable laboratory animal carcases was recommended.

[Cultivation of F. tularensis in developing chick embryos].

In cultivation of the causative agent of tularemia in the organism of chick embryos (8-10 days of incubation) it was found that the virulent strains multiplied intensively in the yolk sacs causing the death of the embryos on the 3rd-4th day after the infection; as to the virulent strains-they were only preserved in the embryos. The period of death of the embryos and the accumulation of bacteria depended on the strain virulence. No differences in the anatomical structure of the cells belonging to the virulent and avirulent strains could be found.

[Use of the immunofluorescence method to detect the causative agent of tularemia in developing chick embryos].

There was shown a possibility of using the immunofluorescent method for detection of the causative agent of tularemia in the developing chick embryos, infected with the virulent strains 503 (holoarctic race) and Schu (nonarctic race). The greatest accumulation of bacteria was revealed in the yolk sacs, and the least--in the chorionallantoic fliud; the greatest accumulation of bacteria was observed on the 3rd--4th days after the infection. In infection with various doses of the causative agent--from 1 milliard to 1 microbial cell-positive results were noted in 92.