Aztreonam plus ceftazidime-avibactam as treatment of NDM-1-producing Klebsiella pneumoniae bacteraemia in a neutropenic patient: Last resort therapy?

Objectives: We report the successful treatment of a bloodstream infection caused by Klebsiella pneumoniae harbouring NDM-1 using aztreonam-ceftazidime-avibactam in a neutropenic patient in whom colistin and meropenem therapy had previously failed. Methods: A clinical isolate was evaluated to determine the presence of NDM, TEM, SHV, CTX, and CMY, and the killing kinetics of aztreonam (ATM; 4 μg/mL), aztreonam-avibactam (ATM-AVI; 4/4 μg/mL), and colistin (2 and 4 μg/mL) were tested. Results: ATM-AVI showed in vitro activity against the Klebsiella pneumoniae harbouring NDM-1, whereas colistin allowed re-growth. Conclusions: This report supports reconsideration of use of colistin for treatment of infections caused by K. pneumoniae harbouring NDM. CZA/ATM use should be kept in mind as a treatment option, perhaps earlier than colistin.