INCREASE OF ANTIMICROBIAL RESISTANCE OF FECAL AEROBIC GRAM-NEGATIVE BACTERIA IN A GERIATRIC HOSPITAL

Antimicrobial resistance of faecal aerobic Gram-negative bacteria to e ight different antimicrobials was determined by a velvet replica-plati ng method in 1988 and 1993. Faecal samples were taken from 131 geriatr ic inpatients in the Turku City Hospital with a hospitalization of mor e than 7 days. From 1987 to 1992 the use of first and second generatio n cephalosporins and ciprofloxacin increased from 3.32 defined daily d oses (DDD) per bed to 24.25 DDD/bed and from 0.63 DDD/bed to 28.11 DDD /bed, respectively. A statistically significant increase was observed in the frequency of samples resistant (with greater than or equal to 1 % of resistant colonies) to cefuroxime (p = 0.0004) and ceftazidime (p = 0.037) in patients who received antimicrobial therapy and to ampici llin (p = 0.046) in patients who had not received antimicrobial therap y. In addition, despite the decreased use of sulphonamides and trimeth oprim (from 17.11 DDD/bed to 5.54 DDD/bed) no significant changes in t he frequency of resistant faecal samples were observed. Use of ciprofl oxacin has been found to eliminate resistance plasmids from bacteria i n vitro. However, despite the increased use of ciprofloxacin, no decre ase in faecal bacteria resistant to any of the other antimicrobials (i .e. trimethoprim) studied was observed.