Clinical variables associated with the isolation of Klebsiella pneumoniae expressing different extended-spectrum β-lactamases

Clinical variables associated with the isolation of Klebsiella pneumoniae expressing different extended-spectrum beta-lactamases (ESBLs) were studied. Clinical records of patients with ESBL-positive K. pneumoniae isolates between 1989 and 2003 (n = 80) were reviewed retrospectively. Patients with SHV- and TEM-type ESBLs were identified more frequently in the intensive care units (67% and 78%, respectively), whereas those with CTX-M ESBLs were found in medical wards (52.2%) or were outpatients (17.4%) (p <0.01). The absence of urinary or central catheters was associated with CTX-M-10 (p 0.013 and p <0.01, respectively). Central catheter-related infections and secondary bacteraemia were associated more frequently with SHV- and TEM-type ESBLs, whereas urinary tract infections were associated with CTX-M-10. Previous aminoglycoside use was associated particularly with SHV-type ESBLs (p <0.01), whereas amoxycillin-clavulanate and oral cephalosporins were associated with CTX-M-10 (p <0.01 and p 0.050, respectively). The frequency of adequate empirical treatment was low (22%), and 61% of patients were treated according to the susceptibility testing results. Mortality (22%) and related mortality (14%) did not differ statistically according to the type of ESBL. Different ESBL types in K. pneumoniae were associated with different clinical variables, and this should be taken into account in current and future epidemiological scenarios.