Use of antimicrobials and resistance in bacteria isolated from blood cultures in a Danish county from 1992 to 1995

To compare the usage of antibiotics and the resistance frequencies in blood culture isolates in a low-consumption area (Roskilde County, Denmark) in the period 1992-1995. Data from relevant institutions were collected and processed. In 1995 the total use of antibiotics was 16.7 defined daily doses (DDD) 1000 inhabitants per day, 95% of this being in the primary healthcare sector. In primary health care, only 0.1% of the total use was cephalosporins, 2% fluoroquinolones, 11% tetracyclines, 29% macrolides and 59% penicillins. In hospitals, 7% were cephalosporins, 3% fluoroquinolones, 0.7% tetracyclines, 10% macrolides and 59% penicillins. The total use in hospitals was 37 DDD/100 bed-days. Resistance frequencies did not change in the period. Resistance against penicillin and erythromycin in Streptococcus pneumoniae was 0.6% and 1.8% respectively. Resistance against methicillin in Staphylococcus aureus was 0.8%, and resistance against ampicillin, cefuroxime, gentamicin and fluoroquinolones in Escherichia coli was 31%, 0.5%, 0.8% and 0.8%, respectively. The frequencies of multiresistant coagulase-negative staphylococci correlated with the use of antibiotics in different ward groups according to the use of antibiotics. In this 4-year study period, the changes in the use of antibiotics were negligible and were not reflected as alterations in the resistance frequencies in single species. In an area with a low use of antibiotics, like Roskilde County, the frequency of multiresistant coagulase-negative staphylococci may reflect the use of antibiotics in different wards. For comparison, it is of great importance to report resistance frequencies and the consumption of antibiotics in different regions in a uniform manner, preferably by DDD/1000 inhabitants per day in the primary healthcare sector and as DDD/100 bed-days in hospitals.