Background: Delafloxacin (DFX), BAXDELA brand name, is a fluoroquinolone antibacterial indicated for the treatment of adults with the following infections caused by designated susceptible bacteria: Acute Bacterial Skin and Skin Structure Infections (ABSSSI) and Community-Acquired Bacterial Pneumonia (CABP). This study evaluated the performance of ETEST® DFX, a new gradient diffusion strip (FDA cleared but not yet CE marked) for determining antimicrobial susceptibility of Gram-positive organisms and Pseudomonas aeruginosa as compared to CLSI M07 broth microdilution reference method (BMD).
Materials/methods: A population of 625 isolates including 287 Staphylococcus aureus (methicillin- resistant and methicillin-susceptible isolates), 46 Staphylococcus haemolyticus, 32 Staphylococcus lugdunensis, 127 Enterococcus faecalis and 133 Pseudomonas aeruginosa were tested at 4 clinical trial sites, including one internal laboratory using ETEST® DFX and BMD. Results were analyzed in terms of essential (EA), category (CA) agreements, minor (mE), major (ME) and very major (VME) error rates using FDA breakpoints in Table 1.
Results: Results are summarized in Table 2. ETEST® DFX performance for each organism met FDA acceptance criteria for EA (≥90%), CA (≥90%), ME (≤3%) and VME (≤2%).
Conclusions: ETEST® DFX shows very good clinical performance characteristics for determining Delafloxacin MIC of S. aureus, S. haemolyticus, S. lugdunensis, E. faecalis and P. aeruginosa.