[Problems in the use of radioactively labelled bacteria in experiments. 2. Quantitative method for the evaluation of pathogens in the calf lung by means of labelled bacteria after aerosol or intratracheal administration].

By means of two aerosol apparatures radioactive labelled Pasteurella-multocida-germs were given to calves via a respiratory mask. Labelling of Pasteurellae was done internal by using special nutritive media with Fe-59 or P-32. In a period of 10-25 minutes 5 X 10(9)-10(10) labelled bacteria were given to the animals for inhalation. Another animal group was injected intratrachealy with the same quantity of labelled germs. Immediately after termination of germ application the animals were killed and dissected. After solution or homogenization, respectively of the total lung tissue radioactivity was determined by liquid-scintillation-counting (Fe-59) or Cerenkov-measurement (P-32), respectively. The activities recovered from lung homogenates rendered is possible to calculate the received amount of bacteria. 40-80% of germs would be recovered in the lung after application by intratracheal injection while only 1-7% could be recovered after individual aerosol application lasting for 15-25 minutes.