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The authors have examined the regularities of the staphylococcal culture filtration through nuclear membranes with pore diameters of up to 0.6 microns, as well as the possibility of sterilization and multiple use of these filters. S. aureus strain No. S. 593 isolated from pathological material has been used as the test bacterium. Routine milk-yolk salt agar and meat-peptone salt broth with 10% NaCl have been employed for the cultivation of the test strain. The filters could be fairly well sterilized with Nikiforov's mixture; then they were dried under a UV bactericidal lamp. The studies have demonstrated that staphylococci can pass through nuclear membranes with pores 0.6 microns in diameter. For sterilization of biologic media membranes with pore diameters of 0.1-0.3 microns are preferable.

The microflora of the skin and the nasal mucosa was studied in 14 healthy newborns, 3 newborns with purulent infections and a nurse working in a neonatal ward. To make this study, washings were obtained with the use of 0.1% Triton X-100 solution. The determination of the number of microorganisms, the percentage of staphylococci, the percentage of lecithinase-positive staphylococci and the number of colonies with antagonistic properties revealed that these characteristics differed according to the state of health of the newborns and the time elapsed after their birth, and that changes in the number of antagonistically active bacteria occurred in parallel with changes in the total number of bacteria. Among S. aureus strains isolated from the subjects covered by the survey strains belonging to phagovar 80, as well as untyped strains, and among S. epidermidis strains those belonging to biovars I and II occurred most frequently. Strains belonging to the same biovar or phagovar differed in their plasmid markers.

A total of 319 strains of S. aureus and 729 strains of S. epidermidis belonging to different biovars isolated from the skin and nasal mucosa of 349 persons representing 8 independent groups were tested. On the whole production of penicillinase was more often observed in the strains of S. aureus than in the strains of S. epidermidis. Within the first species this property was more often detected in the strains of biovar I as compared to the other biovars. However, the frequency of the penicillinase-producing strains within S. aureus and the biovars of S. epidermidis markedly varied.

Comparison of the microbiological, iodometric and acidometric methods for determination of the penicillinase activity of staphylococci showed that the acidometric method was the simplest from the technical viewpoint and available for a wide range of laboratories. Penicillinase is more often produced by Staph. aureus than by Staph. epidermidis. No clear differences between production of penicillinase by various biovars of Staph. epidermidis were detected. The penicillinase activity was most often observed in the strains resistant to penicillin, erythromycin and ther antibiotics. No strains sensitive to zinc and silicon were isolated. Among Staph. aureus 96.15, 84.38, 78.18 and 64.71 per cent of the strains resistant to the ions of cadmium, mercury, plumbum and arsenic respectively produced penicillinase. No such definite results were obtained with respect to the strains of both the whole species of Staph. epidermidis and its separate biovars.

Crude lysates from staphylococcal strains, containing DNA, were capable of transforming Bacillus subtilis at a rate of 1.68 X 10(-10) - 20.6 X 10(-10) depending on the marker according to which the transformers were selected. In a new host, plasmids showed the same behavior pattern as in the staphylococcus but their spontaneous loss was in all the cases recorded significantly more often.

B. subtilis strain 168 was transformed by means of staphylococcal plasmids responsible for resistance to penicillins and levomycetin, as well as for resistance to cadmium ions and for bacteriocinogenicity linked with resistance to cadmium ions. In the new host these plasmids affected the duration of the lag phase and the time of generation. The production of staphylococcal bacteriocin in B. subtilis was accompanied by the lysis of the cells.