Clin Microbiol Infect ABSTRACT: A multicentre, case-control study was conducted to assess risk factors and patient outcomes of bacteraemia caused by Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBLs) and Klebsiella pneumoniae carbapenemases (KPCs). One hundred and five and 20 patients with bacteraemia caused by ESBL-producing and KPC-producing organisms were matched to controls who had bacteraemia caused by non-ESBL/KPC-producing organisms, respectively. Independent risk factors for ESBL production included admission from a nursing home (OR 4.64; 95 CI 2.64-8.16), chronic renal failure (OR 2.09; 95 CI 1.11-3.92), the presence of a gastrostomy tube (OR 3.36; 95 CI 1.38-8.18), length of hospital stay before infection (OR 1.02; 95 CI 1.01-1.03), transplant receipt (OR 2.48; 95 CI 1.24-4.95), and receipt of antibiotics with Gram-negative activity in the preceding 30 days (OR 1.76; 95 CI 1.00-3.08). Twenty-eight-day crude mortality rates for patients infected with ESBL-producing or KPC-producing organisms and controls were 29.1 (34/117) and 19.5 (53/272), respectively (OR 1.70; 95 CI 1.04-2.80). On multivariate analysis, inadequate empirical therapy (OR 2.26; 95 CI 1.18-4.34), onset of bacteraemia while in the intensive-care unit (OR 2.74; 95 CI 1.47-5.11), Apache II score (OR 1.17; 95 CI 1.12-1.23) and malignancy (OR 2.66; 95 CI 1.31-5.41) were independent risk factors for mortality. CTX-M was the most common ESBL type in Escherichia coli, whereas SHV predominated in Klebsiella spp. and Enterobacter spp.