In vitro activities of membrane-active peptides alone and in combination with clinically used antimicrobial agents against Stenotrophomonas maltophilia

The in vitro activities of buforin ZI, cecropin P1, and magainin IF, alone and in combination with six clinically used antimicrobial agents, against 12 clinical isolates of Stenotrophomonas maltophilia were investigated. Antimicrobial activities were measured by MIC and time-kill studies. The isolates were susceptible to the peptides at concentrations in the range of 0.50 to 16 mu g/ml. Synergy was observed when the peptides were combined with polymyxin E, meropenem, ceftazidime, piperacillin, and clarithromycin.