High incidence of Klebsiella pneumoniae clinical isolates to extended-spectrum B-lactam drugs in intensive care units.

A prospective study conducted among Jordanian ICU patients in 1997 using Etest identified resistance rates among isolates of E. coli (25%-44%), Enterobacter spp. (54%-62%), and Klebsiella spp. (30%-80%) to extended-spectrum B-lactams (ESBLs): ceftazidime, cefotaxime, ceftriaxone, and aztreonam. All these isolates were susceptible to imipenem and showed low resistance rate to ciprofloxacin (5%-19%) and amikacin (13%-18%). Higher and significant resistance rates of Klebsiella isolates to ceftazidime (80%) and aztreonam (65%) were observed in 1997 compared with a previous study performed in 1994. The majority of Klebsiella pneumoniae (70%) express different ESBL phenotypes that were almost resistant to aztreonam and ceftazidime but susceptible or resistant to cefotaxime and/or ceftriaxone. This prospective study strongly suggests that ESBL production of Klebsiella pneumoniae isolates have been highly disseminated among ICU patients during 1997.