ANTIBIOTIC-RESISTANCE OF AEROBIC GRAM-NEGATIVE BACILLI ISOLATED IN 1992 IN MARSEILLES

We studied the susceptibility of 10793 bacterial isolates to four broad-spectrum betalactam agents (piperacillin, ticarcillin/clavulanate, cefotaxime or ceftazidime and imipenem), three aminoglycosides (gentamycin, amikacin and tobramycin) and two fluoroquinolones (pefloxacin and ciprofloxacin). The test strains were gram-negative organisms isolated in 1992 from 4 Marseille hospitals (France). Groupe 3 Enterobacteriaceae (Enterobacter, Serratia, indole-positive Proteus, Providencia, Morganella and Hafnia spp. and Citrobacter freundii), Pseudomonas aeruginosa, Acinetobacter baumannii and Stenotrophomonas maltophila represented 46 % of gram-negative isolates during this period. Groupe 1 Enterobacteriaceae (Escherichia coli, Proteus mirabilis, Salmonella and Shigella spp) represented 42 % and Groupe 2 Enterobacteriaceae (Klebsiella pneumoniae, Klebsiella oxytoca and Citrobacter diversus) represented 12 %. Among the Group 1 and 2 Enterobacteriaceae, the susceptibility rate to the test antibiotics was 85 %, with the exception of piperacillin (61 %). Among the group 3 Enterobacteriaceae, with the exception of imipenem, the mean susceptibility rates to betalactam agents were far lower than among groups 1 and 2, with values of 49 %, 57 % and 56 %, respectively, for piperacillin, ticarcillin/clavulanate and cefotaxime. Susceptibility of these isolates to aminoglycosides exceeded 70 %, but the rates of resistance (low and high level) to pefloxacin (41 %) and ciprofloxacin (36 %) were high. Only imipenem. ceftazidime and ticarcillin/clavulanate gave susceptibility rates above 75 % against P. aeruginosa isolates. A. baumannii isolates were far more resistant that P. aeruginosa isolates. Imipenem, ticarcillin/clavulanate and tobramycin were the most active agents, 100 %, 64 % and 52 % of the isolates being susceptible.