Therapeutic challenges associated with extended-spectrum, beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae

The emergence of extended-spectrum beta -lactamase (ESBL)-producing Enterob acteriaceae, particularly Escherichia coh and-Klebsiella pneumoniae, presen ts significant diagnostic and therapeutic challenges to the management of i nfections due to these organisms. Detection of resistant isolates is diffic ult based on routine susceptibility testing performed by a clinical microbi ology laboratory. In addition, the utility of penicillins, cephalosporins, and aztreonam in treating serious infections due to these organisms is unce rtain due to reports of treatment failure despite apparent in vitro suscept ibility A critical evaluation of the English literature was performed on tr eatment outcomes associated with ESBL-producing Enterobacteriaceae. Imipene m and extended-spectrum cephalosporins were commonly administered. Discorda nt outcomes in relation to in vitro susceptibility of the agent did not occ ur exclusively with cephalosporins but with all drugs including imipenem. U ntil more outcome data are available, drug selection must take into conside ration whether or not an outbreak is occurring and whether therapy is empir ical or definitive.