The present disclosure provides hNGAL muteins that bind a pyoverdine family member or pyochelin and can be used in various application including pharmaceutical applications, for example, to inhibit or reduce growth of P. aeruginosa. The present disclosure also concerns methods of making one or more pyoverdine- or pyochelin-binding muteins described herein as well as compositions comprising one or more of such muteins. The present disclosure further relates to nucleic acid molecules encoding such muteins and to methods for generation of such muteins and nucleic acid molecules. In addition, the application discloses therapeutic and/or diagnostic uses of these muteins as well as compositions comprising one or more of such muteins.