Risk factors for relapse or persistence of bacteraemia caused by Enterobacter spp.: a case-control study

Enterobacter spp. possess chromosomal AmpC beta-lactamases that may be expressed at high levels. Previous studies have demonstrated a risk of relapsed bacteraemia following therapy with third generation cephalosporins (3GCs). What additional factors predict microbiological failure in Enterobacter bacteraemia is unclear. We aimed to determine factors associated with microbiological failure in Enterobacter bacteraemia, and retrospectively identified cases of bacteraemia caused by Enterobacter spp. occurring in four hospitals in New South Wales and Queensland, Australia. Using a case-control design, we determined clinical risk factors for persistence or relapse defined as repeated positive blood cultures collected between 72 hours and up to 28 days post initial positive blood culture.