Surveillance of extended-spectrum beta-lactamase-producing bacteria and routine use of contact isolation: experience from a three-year period.

The usefulness and applicability of isolation precautions were questioned for extended-spectrum beta-lactamase (ESBL)-producing strains of Enterobacteriaceae in the endemic setting. We performed a surveillance programme for ESBL-positive organisms and the infection control management of patients colonized or infected with these organisms. Between 1 January 2002 and 31 December 2004, a total of 147 cases of ESBL-producing strains of Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis from 123 patients were noted. The overall incidence of ESBL-producing-strain-positive cases was 0.12/1000 patient-days. The proportion of referred cases was 35% (N=51); 65% of cases (N=96) were acquired in our institution. Infections developed in 57 cases (38.8%), of which 36 (63.3%) were nosocomial. Contact isolation precautions were carried out for 79.6% of the cases, with a median duration of contact isolation precautions for 14 days (range: 0-144). The contact isolation precautions resulted in 2985 isolation days in total, i.e. 995 isolation days per year. Typing by pulsed-field gel electrophoresis showed clonal diversity in 94.2% of the isolates from patients. Seven patient-to-patient transmissions were noted. Only in 10 cases (6.8%) was colonization with ESBL-producing strains cleared. Considering the large number of immunocompromised patients treated in our institution (>1500 bone marrow or solid organ transplantations performed during 2002-2004), we will continue to isolate patients who are colonized or infected with ESBL-producing organisms.