Antibiotic resistance patterns among blood culture isolates in a Danish county 1981-1995

Departments of Clinical Microbiology, University of Aarhus, Denmark * Paediatrics, Aalborg Hospital, University of Aarhus, Denmark Department of Medicine V, Aarhus University Hospital, Denmark Danish Epidemiology Science Centre at the Institute of Epidemiology and Social Medicine, University of Aarhus, Denmark Corresponding author: Dr B. Kristensen. Received February 11, 1998 Accepted April 20, 1998 All episodes of bacteraemia during a 15-year period (1981-1995) in the County of Northern Jutland, Denmark, were analysed with regard to antibiotic resistance. A total of 8840 isolates from 7938 episodes of bacteraemia was identified. Over time, no changes in bacterial aetiology were noted. Three isolates of Staphylococcus aureus were methicillin resistant (0.2%) and six were gentamicin resistant (0.4%). Among coagulase-negative staphylococci a 14% increase in resistance to penicillin was observed (95% confidence intervals, CI: 2-26%). Likewise, the frequency of resistance to methicillin, gentamicin and erythromycin increased, the corresponding figures being 38% (CI: 26-50%), 26% (CI: 14-38%) and 32% (CI: 16-50%), respectively, whereas a 14% decrease in resistance to streptomycin was recorded (CI: 4-24%). A 20% (CI: 2-37%) increase of coagulase-negative staphylococci resistant to three or more antibiotics was observed. The frequency of ampicillin resistance increased by 9% among Escherichia coli (CI: 4-13%) and by 10% (CI: 6-14%) in all Enterobacteriaceae. Among Enterobacteriaceae the level of resistance to third-generation cephalosporins, carbapenems, aminoglycosides and fluoroquinolones remained low (