The present disclosure is directed to lysin-AMP polypeptide constructs, isolated lysin polypeptides, and pharmaceutical compositions comprising the isolated polypeptides and/or lysin-AMP polypeptide constructs. Methods of using the lysin-AMP polypeptide constructs, isolated lysin polypeptides and pharmaceutical compositions are also herein provided, including methods of treating a bacterial infection of an organ or tissue in which pulmonary surfactant is present or Gram-negative bacterial infections that are associated with a biofilm. In addition, isolated polynucleotides encoding the lysin-AMP polypeptide constructs and isolated lysin polypeptides are disclosed herein.

Disclosed herein are pharmaceutical compositions comprising an effective amount of an isolated Chp peptide having an amino acid sequence selected from the group consisting of SEQ ID NOs. 1-4, 6-26 and 54-66, or a modified Chp peptide having about 80% sequence identity therewith, wherein the modified Chp peptide inhibits growth, reduces the population, or kills at least one species of Gram-negative bacteria; and a pharmaceutically acceptable carrier. Further disclosed herein are isolated Chp peptides, as well as vectors comprising a nucleic acid molecule that encode the Chp peptides and host cells comprising a vector. Also disclosed herein are methods of inhibiting the growth, reducing the population, or killing of at least one species of Gram-negative bacteria and methods of treating a bacterial infection in a subject.