postulate that people get pneumonia, not get infected with it. 2 And although Streptococcus pneumoniae (SP) or Pneumococcus (P) was isolated in 1886, which prevailed among the pathogens of AP and got its name because of this exceptional propensity, 3 but the fundamental foundations of the etiology of this disease and its main propertiesnon-specificity and non-contagiousness -were formulated already at the dawn of the development of microbiology.It should be noted that the dominant role of SP among the pathogens of AP remained stable for a long period. Periodic statistics on the etiology of this disease consistently showed the presence of P as the causative agent in 95 percent or more of cases. Such figures were presented in 1917, 4 in 1927, 5 in 1933, 6 in 1939 7 and in 1948. 8 According to the materials of the presented statistical data, P remained the leader among the pathogens of AP for more than 30 years, without reducing the level of its prevalence is below 95%. And if we take into account the leadership of SP in inflammation of lung tissue since it was first discovered and, due to its superiority, received its name, then the duration of stable statistics of the etiology of AP exceeds at least six decades.If we focus on the preserved statistics of the etiology of AP, then starting from the first results of studying this characteristic of the disease in the 19th century and up to the 40s of the last century, its main causative agent was SP, which consistently maintained almost one hundred percent participation in this inflammatory process. However, as the subsequent course of events has shown, the efforts of medicine to widely use etiotropic therapies have changed the usual proportions of the etiology of AP.