X-ray data of 80 patients with different purulent lung processes were analysed. Three groups of patients with acute infectious lung destructions were singled out.

In the first group the purulence was caused by anaerobes and their association with other bacteria. In the second — gram-negative organisms and their associations with other bacteria, and in the third — staphylococcus was the main cause of purulent process. The analysis of X-ray data did not reveal any significant features which can be used as a differential diagnostic criteria of different microbic factors. Thus, the exact ethiologic diagnosis of purulent lung process based on X-ray data is impossible.