ANTIMICROBIAL SUSCEPTIBILITY PATTERN OF GRAM-NEGATIVE AEROBIC ISOLATES FROM INTENSIVE-CARE UNITS IN SAUDI-ARABIA - A MULTICENTER STUDY

Objective: To determine the pattern and prevalence of recognized categ ories of resistance to broad-spectrum antibiotics in seven Intensive C are Units (ICUs) in the Kingdom. Design: A multicenter study was estab lished to carry out susceptibility tests on at least 100 isolates from patients admitted into ICUs of seven hospitals in various areas in th e Kingdom. Tests were performed using the Microscan MIC Plus type MIC panel. Setting: Microbiology laboratories and ICUs of seven hospitals in the Kingdom. Subjects: Four hundred and seventy eight patients admi tted into the study provided 703 isolates, which were examined for bet a-lactamase production. Main outcome measures: The dominant species is olated were Ps. aeruginosa (148), E. coli (117) and Kleb. pneumoniae ( 11). Results: In all but one center, most isolates resistant to 3rd ge neration cephalosporins were E. coli and Klebsiella spp. with multi-re sistance pattern consistent with extended spectrum B-lactamase (ESBL). Inducible Enterobacteriaceae (IE), with chromosomal type-1 cephalospo rinases were next in importance, followed by Ps. aeruginosa. Amikacin was the most effective aminoglycoside least affected by IE, while amox il/clavulanate had a low impact on conferring sensitivity on the isola tes. Conclusions: Blood culture isolates showed a strong contribution of resistance from inducible Enterobacteriaceae, principally nosocomia l Serratia spp. and Enterobacter spp. with linked resistance to the am inoglycosides. The superiority of imipenem and ciprofloxacin over othe r antibiotics for empiric therapy of bacteremia in ICU patients was ev ident from the susceptibility data of all isolates.