[Behaviour of gram-positive and gram-negative bacteria in dry and moist atmosphere (author's transl)].

The results of bacteriologic environmental studies show the frequently appearance of Staphylococci in dry and of Pseudomonas in moist atmosphere. There is a small frequency of Enterobacteriaceae in both cases. Therefore experiments are done about the behaviour in dry atmosphere of 5 different strains of Staph. aureus, Strept. faecalis, E. coli, Kl. pneumoniae, S. marcescens and P. aeruginosa. The bacterial suspensions are scored on aluminium foil and exposed at room temperature and constant air-moisture. The results show Enterobacteriaceae more sensitive for drying as Staph. aureus and Strept. faecalis. In dry atmosphere Pseudomonas is nearly not able to survive. In contrary to the other examined bacteria only Staphylococcus can be transfered by air or dust. The behaviour in moist environment is examined at room temperature in aqua bidest. and sterile tap-water. In both liquids only S. marcescens is able to grow. It is conspicous that P. aeruginosa dies off in aqua bidest, within 4 d while it is able to grow in tap-water. In tap-water the initial colony count of E. coli keeps constant, but in aqua bidest. E. coli is no more present after 24 d. In both liquids, Staph. aureus and Strept. faecalis have limited surviving rates: Staph. aureus can't be cultured in aqua bidest, after 5 d, in tap-water after 7 d, Strept. faecalis survive 11 and 10 d respectively. Additional the behaviour in tap-water is examined at 30 degrees C and 40 degrees C. These temperatures are characteristic for ultrasonic nebulizers and humidifiers respectively. At both temperatures only P. aeruginosa is able to grow. The other bacteria--including S. marcesens--die off at 30 degrees C and even faster at 40 degrees C. Furthermore mixed cultures are made with 5 strains each of Staph. aureus (= St), Strept. faecalis (= Sf), E. coli (= Ec), S. marcescens (= Se) and P. aeruginosa (= Pa) which formed the following groups: St/Sf, St/Ec, St/Se, St/Pa, Sf/Ec, Sf/Se, Sf/Pa, Ec/Se, Ec/Pa, Se/Pa. The examinations are done in aqua bidest. and tap-water at room temperature. Additional the behaviour in tap-water at 30 degrees C and 40 degrees C was tested. A mutual influence cannot be found. It is the conclusion to use the humidifiers and nebulizers with sterile aqua bidest. only and to prefer the humidifiers to the nebulizers.