Failure of ceftazidime-amikacin therapy for bacteremia and meningitis due to Klebsiella pneumoniae producing an extended-spectrum β-lactamase

A multiple trauma patient failed treatment with ceftazidime and amikacin for bacteremia and meningitis due to a Klebsiella pneumoniae strain that produced a novel, plasmid-mediated β-lactamase. Both pre- and posttreatment isolates were resistant to ceftazidime (MIC, ≥ 64 μg/ml) and various penicillins but not to other expanded-spectrum cephalosporins. The β-lactamase had a pI of 5.25 and was encoded on the conjugal plasmid of approximately 150 kilobases. DNA hybridization studies indicated that the enzyme was a TEM derivative.