Incidence of multi-resistance in gram-negative aerobes from intensive care units of 10 German hospitals.

At the beginning of 1990, 10 German hospitals participated in a surveillance study of 100 consecutively submitted Gram-negative aerobes originating in their intensive care units (ICUs). A total of 1,006 isolates were obtained from 446 patients. Resistance rates cited apply to the initial strains isolated and use the NCCLS fully susceptible breakpoint. Over 1/3 of the penicillin resistant populations of E. coli and Klebsiella spp. were resistant to amoxicillin/clavulanate and simultaneously resistant to cefazolin and cefuroxime. These resistance patterns were found in 9/10 hospitals. Resistance to 3rd generation cephalosporins was rare and confined to 2/10 centers. Enterobacteriaceae with inducible beta-lactamase, e.g. Enterobacter spp., Serratia spp., C. freundii and Morganella spp., were in all centers the major source of isolates resistant to 3rd generation cephalosporins and ureidopenicillins. Cross-resistance between these agents was extensive. Both imipenem and ciprofloxacin remained active against this species group. Resistance rates to anti-pseudomonal agents ranged from 10 to 20%. Analysis of cross-resistance in P. aeruginosa revealed a correlated magnitude of resistance between cephalosporins and penicillins, but none toward imipenem. Resistance acquisition reached 50% for cephalosporins in those patients providing repeated isolates of the inducible Enterobacteriaceae. High rates of resistance development prior to and during ICU occupancy could explain why rates of resistance observed in this study were 1.6-fold higher than reported in recent surveys of hospital-wide isolates from Germany. Resistance patterns seen from the ICU suggest that prescribing doctrine be reappraised to limit practices engendering resistance to large families of related antibiotics.