[Sensitivity tests on bacterial strains from respiratory tract: comparison between direct and on isolated strains...

The validity of the direct antimicrobial disc susceptibility test has been compared with the same test carried out on bacterial strains isolated from clinical materials obtained from the respiratory tract. The experimental evidence so far obtained raises some doubts concerning the reiliability of the direct test. The use of the latter seems to be reccomended in urgent cases only considering that either with multimicrobic or monomicrobic material the results obtained are partial and slightly reproducible. The conclusion is that, in order to obtain an accurate picture of the sensitivity to the various antibiotics, the direct test should be followed always with the antimicrobial disc susceptibility test carried out with isolated strains.