RESISTANCE TO 16 ANTIBIOTICS IN 3,876 GRA M-NEGATIVE AEROBES ISOLATESISSUED FROM 39 INTENSIVE-CARE UNITS (ICU) IN FRANCE (1991)

The Minimal Inhibitory Concentrations (MIC's) in a liquid medium of im ipenem (IPM) and 15 other antibiotics (ampicillin, amoxicillin-clavula nic acid, mezlocillin, piperacillin (PIP), cefazoline, cefuroxime, cef oxitin, cefotaxime (CFT), ceftriaxone (CAX), ceftazidime (CAZ), aztreo nam (AZT), gentamicin, tobramycin (TOB), amikacin, ciprofloxacin (CP)) were determined towards 3.876 Gram negative aerobes isolated serially from bacteriological swabs obtained from patients hospitalised in Int ensive Care Units in 39 centres during 1991. The organisms recruited c omprised 2.773 ''initial'' isolates and 593 ''repeat'' isolates (%). P seudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Kleb siella pneumoniae and Proteus mirabilis represented 68 % of the ''init ial'' isolates ; P. aeruginosa alone represented nearly one-half of th e ''repeat'' isolates. Taking all the ''initial'' isolates together, t he rate of antibiotic resistance (%) was as follows : IPM 9, CAZ 23, C AX 46, AZT 34, PIP 50, CP 29. Eighty percent of the strains resistant to IPM came from the species P. aeruginosa, Xanthomonas maltophilia, a nd Pseudomonas cepacia. The percentage of P. aeruginosa resistant to I PM varied from 0 to 65 % depending on the center, the resistance of K. pneumoniae to CAZ varied from 0 to 75 %, that of E. cloacae and A. ba umannii to CAZ from 0 to 100%. Versus bacterial species other than P. aeruginosa, the resistance to CAZ, CAX, AZT, CFT, and PIP was higher t han with IPM. This resistance was seen mainly in A. baumannii, extende d-spectrum beta-lactamase producing K. pneumoniae, and enterobacteriac eae capable of producing high levels of cephalosporinase, organisms wh ich were frequently found in numerous centers. Among the ''repeat'' is olates, there was a very significant increase in resistance, in partic ular in P. aeruginosa. These results show a very wide diversity in the distribution of bacterial strains and the incidence of bacterial resi stance in France.