Antimicrobial susceptibility pattern of gram-negative aerobic isolates from intensive care units in Saudi Arabia; a multicenter study

ABSTRACT

To determine the pattern and prevalence of recognized categories of resistance to broad-spectrum antibiotics in seven Intensive Care Units [ICUs] in the Kingdom. A multicenter study was established to carry out susceptibility tests on at least 100 isolates from patients admitted into ICUs of seven hospitals in various areas in the Kingdom. Tests were performed using the Microscan MIC Plus type MIC panel. Setting: Microbiology laboratories and ICUs of seven hospitals in the Kingdom. Four hundred and seventy eight patients admitted into the study provided 703 isolates, which were examined for beta-lactamase production. The dominant species isolated were Ps. aeruginosa [148], E.coli [117] and Kleb. pneumoniae [11]. In all but one center, most isolates resistant to 3rd generation cephalosporins were E. coli and Klebsiella spp. with multi-resistance pattern consistent with extended spectrum B-lactamase [ESBL]. Inducible Enterobacteriaceae [IE], with chromosomal type-1 cephalosporinases were next in importance, followed by Ps.aeruginosa. Amikacin was the most effective aminoglycoside least affected by IE, while amoxil/clavulanate had a low impact on conferring sensitivity on the isolates. Blood culture isolates showed a strong contribution of resistance from inducible Enterobacteriaceae, principally nosocomial Serratia spp. and Enterobcater spp. with linked resistance to the aminoglycosides. The superiority of imipenem and ciprofloxacin over other antibiotics for empiric therapy of bacteremia in ICU patients was evident from the susceptibility data of all isolates