Evaluating the level of nitroreductase activity in clinical Klebsiella pneumoniae isolates to support strategies for nitro drug and prodrug development

•Nitroreductase (NR) activity levels vary considerably between Klebsiella pneumoniae isolates.•High NR activity correlates with susceptibility to nitrofurantoin.•Epidemic strains, such as from ST258 and ST11, are almost all resistant to nitrofurantoin.•Design of novel nitro-containing drugs could be useful for treating infections.