A multicenter study for monitoring antimicrobial drug resistance in clinical isolates of the family Enterobacteriaceae, Pseudomonas aeruginosa, Staphylococcus and Enterococcus species in central Europa conducted by the Study Group Bacterial Resistance of the Paul-Ehrlich-Society for Chemotherapy has been ongoing since 1975, Between 1975 and 1995 susceptibility data on almost 60,000 bacteria, which were isolated and sampled under a common protocol by laboratories from Austria, Germany and Switzerland, were collected, These bacterial isolates were known by the respective investigators to have caused infections, From 1975 to the mid-80s none of the bacterial species examined showed an increase in resistance. The frequency of resistance in klebsiellae and Staphylococcus aureus to some antibiotics even declined. In 1990 and particularly in 1995, a clear increase in resistance for a number of antibiotic-organism pairs was observed. Resistance rates to fluoroquinolones increased in all species under investigation. In Escherichia coli the increase of resistance to ampicillin, co-trimoxazole and gentamicin was remarkable. Resistance to imipenem increased in P. aeruginosa. Resistance to cephalosporins, on the other hand, remained largely unchanged in gram-negative bacilli. Between 1990 and 1995, the prevalence of oxacillin resistance increased from 1.7 to 12.9% in S, aureus and from 15.8 to 55.8% in coagulase-negative staphylococci, whereas staphylococcal and enterococcal resistance to glycopeptides was still rare.
