Multiply beta-lactam resistant Enterobacter cloacae infections linked to the environmental flora in a unit for cardiothoracic and vascular surgery.

During the period March 1987-May 1988, postoperative infection or colonization with Enterobacter cloacae occurred in 9/379 (2.4%) patients who underwent cardiovascular surgery. Five of the patients were infected with multiply beta-lactam resistant E. cloacae, of whom 4 had been infected with an identical, resistant strain during intervals of months. This strain was also found in the environmental flora of the cardiovascular operating suite and in a sink reservoir in the surgery department. All 4 patients with the identical resistant strain had serious complications during the postoperative period with symptoms of septicaemia in 3, multiorgan failure and shock in 2, and mediastinitis in 3. The single resistant strain of a different serotype was also associated with severe postoperative complications. The 4 sensitive strains were all different serotypes. None caused septicaemia, one was associated with mediastinitis, another with an uncomplicated sternum infection, and 2 were from sputum. In the 3 latter patients with sensitive strains and few postoperative complications, cephalosporins had not been used during the pre- or postoperative period.