[Resistant gram-negative bacteria at seven intensive care units in Denmark]

A prospective study on the prevalence of resistance to 16 antibiotics in 704 Gram-negative bacteria isolated from seven intensive care units was undertaken in 1990. A microtitre panel carrying 16 antibiotics was used for susceptibility testing. The study revealed minor differences in resistance between the participating centres. The overall resistance was relatively low in Denmark, but there was increased resistance among E. coli from intensive care units compared to E. coli isolates from bloodcultures collected in 1988. At one centre the susceptibility of P. aeruginosa to gentamicin was slightly lower than at other centres, indicating a minor outbreak during the collection period. P. aeruginosa and Enterobacteriaceae with inducible production of beta-lactamases showed cross-resistance between penicillins and cephalosporins, but not between penicillin/cephalosporins and imipenem gentamicin or ciprofloxacin. The resistance among the repeated isolates of inducible Enterobacteriaceae was slightly higher than among the initial isolates indicating acquisition of resistance or selection of resistant mutants.