<i>In Vitro</i> Activity Analysis of a New Polymyxin, SPR741, Tested in Combination with Antimicrobial Agents against a Challenge Set of <i>Enterobacteriaceae</i> , Including Molecularly Characterized Strains

Abstract

The activities of azithromycin, fusidic acid, vancomycin, doxycycline, and minocycline were evaluated alone and in combination with SPR741. A total of 202 Escherichia coli and 221 Klebsiella pneumoniae isolates were selected, and they included a genome-sequenced subset ( n = 267), which was screened in silico for β-lactamase, macrolide-lincosamide-streptogramin (MLS), and tetracycline ( tet ) genes. Azithromycin (&gt;16 mg/liter), fusidic acid (&gt;64 mg/liter), vancomycin (&gt;16 mg/liter), and SPR741 (&gt;8 mg/liter) showed off-scale MICs when each was tested alone against all isolates.

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