Bacteraemia due to extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) in cancer patients: clinical features, risk factors, molecular epidemiology and outcome.

OBJECTIVES

To assess the clinical features, risk factors, molecular epidemiology and outcome of extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-EC) bacteraemia in hospitalized cancer patients.

METHODS

Episodes of ESBL-EC bacteraemia were compared with a susceptible control group in a 3 year prospective study. ESBL-EC strains were studied by PCR and isoelectric focusing, and molecular typing was performed by PFGE.

RESULTS

Out of 531 episodes of bacteraemia, 135 were caused by E. coli. Seventeen of these cases involved ESBL-EC-producing strains (12.6%). In the multivariate analysis, female gender [odds ratio (OR) 3.43; 95% confidence interval (CI) 1.03-11.4] and previous antibiotic therapy (OR 3.22; 95% CI 1.00-10.3) were found to be independent risk factors for ESBL acquisition. An analysis of ESBL-EC isolates revealed a polyclonal distribution with CTX-M predominance (59%). Patients with ESBL-EC bacteraemia were more likely to have received an inadequate empirical antibiotic therapy (65% versus 6%; P = 0.000), and the time to adequate therapy was longer in this group (0 versus 1.50 days; P = 0.000). The overall mortality rate was 22%, ranging from 20% to 35% (P = 0.20). Risk factors for mortality were solid tumour (OR 19.41; 95% CI 4.66-80.83), corticosteroid therapy (OR 3.04 95% CI 1.05-8.81) and intensive care unit admission (OR 248.24, 95% CI 18.49-3332.14). In neutropenic patients, ESBL-EC bacteraemia was associated with poorer outcome and a higher overall mortality rate (37.5% versus 6.5%; P = 0.01).

CONCLUSIONS

In our centre, ESBL-EC bacteraemia is frequent among cancer patients, especially in those exposed to antibiotic pressure. All ESBL-EC strains were unrelated and most of them carried a CTX-M group enzyme. Patients with ESBL-EC bacteraemia received inadequate empirical antibiotic therapy more frequently than patients carrying a susceptible strain, but significant differences in mortality could not be demonstrated.