Impact of rapid diagnostic tests on the management of patients presenting with Enterobacteriaceae bacteremia

Objective

Pathogens are usually identified from blood cultures using a two-step procedure: Gram staining on the day of bacterial growth (D0), followed by identification and susceptibility testing the following day (D1). We aimed to evaluate the use of rapid tests performed on D0 in patients presenting with Enterobacteriaceae bacteremia.

Patients and methods

Patients with ≥ 1 positive monomicrobial blood culture with Gram staining suggestive of an Enterobacteriaceae were prospectively included. Two successive strategies were evaluated: i) conventional strategy (CS), ii) combination of a rapid identification test and third-generation cephalosporin susceptibility testing (rapid strategy, e.g. RS).

Results

Eighty-three patients were included (CS = 42; RS = 41). Compared with CS, the median delay of identification was significantly shorter with RS (22 hours 20–27] vs. 47 hours 42–53]; P < 0.001). Patients in the RS group more frequently received an effective (82.9% vs. 73.8%, P = 0.43) and appropriate (70.7% vs. 54.7%, P = 0.17) antibiotic therapy on D1. Moreover, all five RS patients infected with a non-susceptible strain received an effective therapy on D1 versus only three of eight CS patients.

Conclusions

Use of rapid testing was associated with a reduced time to result availability. This strategy should be useful to initiate an early effective and appropriate therapy and to improve the care of patients.