Incidence of antibiotic resistance in blood and urine isolates from hospitalized patients. Report from a European collaborative study. European Study Group on Antibiotic Resistance (ESGAR).

During 1992-93, 2544 isolates from blood cultures, comprising 52% gram-negative bacilli, 24% Staphylococcus aureus, 15% other staphylococci, 7% Enterococcus faecalis and 2% E. faecium, were consecutively collected and identified in 30 laboratories in 21 European countries. In addition 2512 urine isolates, comprising 82% gram-negative bacilli, 3% S. aureus, 4% other staphylococci and 11% enterococci were collected. The bacteria were sent to 3 laboratories for susceptibility testing by the microdilution method in Mueller-Hinton broth. The MICs of penicillins and aztreonam for all susceptible gram-negative bacilli were 0.25-8 mg/l, penems 0.032-2 mg/l, cefotaxime, ceftazidime and cefpirome or cefepime 0.032-0.25 mg/l, gentamicin, tobramycin and netilmicin 0.125-2 mg/l, amikacin 0.5-4 mg/l, ciprofloxacin 0.016-1 mg/l, trimethoprim 0.25-1 mg/l and tetracycline 1-2 mg/l. For susceptible staphylococci the MICs of erythromycin were 0.25-0.5 mg/l, clindamycin 0.125-0.25 mg/l, methicillin 2-8 mg/l, vancomycin and trimethoprim 1-4 mg/l, ciprofloxacin 0.25-1 mg/l, gentamicin and tobramycin 0.25-1 mg/l. For the enterococci the MICs of ampicillin and vancomycin were 2-4 mg/l and of imipenem, teicoplanin and trimethoprim 0.5-1 mg/l. The antibiotic resistance rates varied between laboratories, being lower in northern Europe, except for the penems, cefpirome and cefepime, which showed uniformly lower resistance rates. Compared to the earlier European studies the resistance rates to beta-lactam antibiotics among the gram-negatives have not changed except with an increase to cefotaxime and ceftazidime in central Europe. Resistance to aminoglycosides had also increased in central Europe from 7-8% to 20-21%, but decreased in southern Europe from 22-24% to 13-14% among the blood isolates and from 12-28% to 6-7% among the urine isolates. There was an increase in resistance to ciprofloxacin and gentamicin in staphylococci from southern Europe. The prevalence of MRSA was significant in central and southern Europe. It is of importance that collaborative national and international studies on the incidence of antibiotic resistance are being performed on a repetitive basis.