Extended-spectrum beta-lactamases in clinical isolates of Escherichia coli and Klebsiella spp. in a Singapore hospital: clinical spectrum.

INTRODUCTION The rising prevalence of extended-spectrum beta-lactamases in gram-negative bacillary pathogens is an important clinical problem resulting from the extensive use of broad-spectrum antibiotics. The emergence of the extended-spectrum beta-lactamases increases the possibility that traditional, empiric antimicrobial regimens may be ineffective. The aims of this study are: to determine the epidemiologic characteristics and clinical outcome of patients diagnosed with infection caused by Klebsiella spp. and Escherichia coli producing extended-spectrum beta-lactamases; to define a subgroup of patients who may benefit from early, empiric therapy; and to determine the local antibiotic sensitivity pattern in order to improve antibiotic utilisation in our hospital. MATERIALS AND METHODS A 4-month retrospective review of patients hospitalised in Changi General Hospital between November 2000 and February 2001 who were diagnosed with infection caused by isolates of Klebsiella spp. or Escherichia coli producing extended-spectrum beta-lactamases. RESULTS During the study period, 44 % of Klebsiella spp. and 16.1 % of Escherichia coli isolates were reported as producers of the extended-spectrum beta-lactamases. Sixty-eight patients were assessed to have clinically significant infection caused by 75 isolates. Most of them were elderly, had multiple medical problems and were recently treated with beta-lactam antibiotics. There was a trend toward better outcome in patients who received adequate initial, empiric therapy. CONCLUSION Patients with infections caused by extended-spectrum beta-lactamase producing Enterobacteriaceae have certain identifiable, common clinical characteristics. In our institution, only carbapenems remain effective against all isolates of Klebsiella spp. or Escherichia coli producing extended-spectrum beta-lactamases. Further research is necessary to define a group of patients who can benefit from an early, broad-spectrum, empiric therapy.