Outbreak of infections caused by Enterobacter cloacae producing the integron-associated beta-lactamase IBC-1 in a neonatal intensive care unit of a Greek hospital.

Nineteen of 27 ceftazidime-resistant Enterobacter cloacae isolates from a neonatal intensive care unit in Thessaloniki, Greece, had genes coding for the novel extended-spectrum beta-lactamase IBC-1; 18 of those 19 harbored similar conjugative plasmids and belonged to two distinct genetic lineages. A synergy test with ceftazidime and imipenem enabled us to identify five unrelated bla(IBC-1)-carrying E. cloacae isolates from other wards of the hospital. It seems that this integron-associated gene is capable of dispersing both by clonal spread and by gene dissemination.