Mortality following bacteraemic infection caused by extended spectrum beta-lactamase (ESBL) producing E. coli compared to non-ESBL producing E. coli.

Objectives: To determine the differences in mortality and length of hospital stay in patients with bacteraemic infection caused by ESBL and non-ESBL producing Escherichia coli. Main outcome measures were mortality, time from bacteraemia to death and length of inpatient stay.

Methods: From June 2003 to November 2005, we prospectively collected clinical and microbiological data on all adult patients with E. coli bacteraemia.

Results: ESBL producing E. coli caused 16/242 (6.6%) community-acquired and 30/112 (26.8%) hospital-acquired bacteraemic infections. The most common sites of infection were urine 239/354 (67.5%) and bile 41/354 (11.6%). All ESBL producers were resistant to cephalosporins. Resistance to ciprofloxacin, trimethoprim, gentamicin and amikacin were 42/46 (91.3%), 39/46 (84.8%), 14/46 (30.4%) and 2/46 (4.3%), respectively. A significantly higher proportion of patients died following a bacteraemic infection caused by ESBL producing E. coli, 28/46 (60.8%), compared to non-ESBL producing E. coli, 73/308 (23.7%). The adjusted odds ratio for death was 3.57 (95% CI 1.48-8.60, p<0.005). Delay in initiating an appropriate antibiotic was significantly associated with death and ESBL production. There was no significant difference between time from bacteraemia to death (median time 7 days (ESBL +ve group) vs 5 days (ESBL -ve group); p=0.69) and, in those who survived, length of inpatient stay (median time 9 days (ESBL +ve group) vs 12 days (ESBL -ve group); p=0.111).

Conclusions: Mortality following bacteraemic infection caused by ESBL producing E. coli was significantly higher than non-ESBL producing E. coli. These findings have serious implications for antibiotic prescription, as cephalosporins are ineffective treatment for many E. coli infections.