It was an extraordinary pleasure for me, as the secretary general, to organise, with my collaborators, this Second International Symposium on Antibiotic Resistance in the Castle of Smolenice in Czechoslovakia. We all appreciated many offers all participants must have spent to attend this Symposium and we were glad to do our best to prepare this meeting in a suitable and convenient way. We gathered in Smolenice Castle after the significant International Congress on Che motherapy in September 1973 in Athens. We had the chance of getting acquainted, on that world-wide forum, with the latest information about bacterial resistance to anti biotics. It was possible at that Congress to outline main topics of interest in the field of bacterial resistance to antibiotics which then have been placed on the programme of the subsequent Smolenice Symposium. Undoubtedly, enzymatic mechanisms by which bacteria can inactivate older and newer antibacterial drugs and which can be transmitted and spread among bacterial strains, have both medical as well as theoretical priority. Dealing specially with Pseudomonas aeruginosa is highly urgent at present from the clinical, hygienical and genetical point of view. We have realised that antibiotics have ceased to be "magic bullets" which hit the microorganisms without discrimination. Today we urgently consider the question what should be done in the area of "antibiotic policy" to preserve the effectiveness of antibiotics for the future.

The first useful antibiotic found by screening was streptomycin. The late Prof. WAKSMAN started screening for antibacterial antibiotics in 1940 and, after finding actinomycin in 1941, he and his collaborators discovered streptomycin in 1944. This antibiotic made a great contribution in saving human lives from tuberculosis and acute serious infections. About 1957, after wide usage of such antibiotics as penicillin, streptomycin, chloramphenicol, tetracycline, and erythromycin, staphy- lococci and Gram negative organisms resistant to all or most antibiotic drugs ap- peared in hospital patients. The origin and treatment of such resistant strains be- came a major topic of investigation. At that time, kanamycin was discovered and used in the treatment of resistant infections. It may be said that the appearance of resistant strains stimulated a resurgence of research on new antibacterial antibiot- ics and their derivatives. In 1965, kanamycin-resistant strains were found in hospital patients and, undertaking the study of the mechanisms of resistance, I found that resistant strains produce intracellular enzymes that can transfer either the terminal phos- phate of ATP or the acetate of acetyl-CoA to the 3' -hydroxyl or the 6' -amino group of 2-deoxystreptamine~containing antibiotics. These results, reported in 1967, made it possible to design new synthetic derivatives that would inhibit the growth of kanamycin resistant strains of microorganisms. Thus, a new research area was opened: the development of aminoglycosides useful in the treatment of drug-resis- tant infections.