Medically important micro-organisms recovered from Apollo-Soyuz Test Project (ASTP) crew members.

The possibility of significant alterations in the microbial populations inhabiting the integument and upper respiratory tract of space flight crew members has been proposed by various authors. The Apollo-Soyuz Test Project (ASTP), a unique space flight in which two teams of crew members from different geographical areas joined in space, presented an unusual opportunity to evaluate in-flight cross-contamination and other anomalous behavior of the microbial populations. Accordingly, the medically important microbes recovered from the five (3 USA and 2 USSR) ASTP crew members before and after flight were evaluated in relation to specific theoretical alterations. The phenomenon of "simplification", in which the number of different types of species is reduced during spaceflight, did not occur within the population of medically important micro-organisms. Spontaneous post-flight illness due to infectious agents ("Microbial Shock") was also absent. Intracrew transfer of pathogens was established, but intercrew transfer was absent. Dysbacteriosis, in which sampled areas are flooded with unusually large numbers of a single type of micro-organism, was not demonstrated although there was a significant increase in the incidence of gram-negative rods in the oral cavities of the two cosmonauts. The importance of all of these and other observations of the medically important micro-organisms recovered from ASTP crew members are explored with respect to past and future space flights.