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Bacillus cereus growing in nutrition broth produces during logarithmic growth and in stationary phase a lethal factor extremely toxic for rodents. This toxin is only produced in the presence of oxygen and depends on bacterial replication. The highest titers of toxin are obtained using bacteria in a concentration of 10(7) to 10(9) per ml of nutrition broth. During regression phase of Bacillus cereus the titer of toxin declines to zero. Toxicity of the lethal factor becomes not altered in an alcaline or acidic medium. Temperatures exceeding 65 degrees C inactivate the toxin indicating its thermolability. Oral and rectal dispension of large quantities of the lethal factor does not induce toxic symptoms in rodents. However, when applicating toxin containing cultural filtrate of Bacillus cereus as an i.v., i.p., i.n. or s.c. injection it becomes highly toxic for mice, rats, hamsters, guinea pigs and rabbits. All animals injected by the different ways parenterally died.

The importance of the public swimming bath for the dissemination of Trichomonas vaginalis is disputed. 30 samples, each of 250 ml bath water from four indoor swimming baths, were examined for trichomonads. All the samples were negative. 218 smears taken from the wet places on the heated benches and other seating accommodation in these swimming baths were cultured for trichomonads and bacteria. Trichomonas vaginalis could not be demonstrated. Fecal organisms were found in 56 places, antibiotic-sensitive staphylococci were cultured from 20 samples and Ps. aeruginosa from 8. The negative tests for trichomonads suggests that the indoor swimming bath has no epidemiological importance in the dissemination of this parasite.