Clinical characteristics of bacteraemia caused by extended-spectrum β-lactamase-producing Enterobacteriaceae in the era of CTX-M-type and KPC-type β-lactamases

A multicentre, case-control study was conducted to assess risk factors and patient outcomes of bacteraemia caused by Enterobacteriaceae producing extended-spectrum β-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.