title: Cationic synthetic peptides: assessment of their antimicrobial potency in liquid preserved boar semen.
abstract: Various semen extender formulas are in use to maintain sperm longevity and quality whilst acting against bacterial contamination in liquid sperm preservation. Aminoglycosides are commonly supplemented to aid in the control of bacteria. As bacterial resistance is increasing worldwide, antimicrobial peptides (AMPs) received lively interest as alternatives to overcome multi-drug resistant bacteria. We investigated, whether synthetic cationic AMPs might be a suitable alternative for conventional antibiotics in liquid boar sperm preservation. The antibacterial activity of two cyclic AMPs (c-WWW, c-WFW) and a helical magainin II amide analog (MK5E) was studied in vitro against two Gram-positive and eleven Gram-negative bacteria. Isolates included ATCC reference strains, multi-resistant E. coli and bacteria cultured from boar semen. Using broth microdilution, minimum inhibitory concentrations were determined for all AMPs. All AMPs revealed activity towards the majority of bacteria but not against Proteus spp. (all AMPs) and Staphylococcus aureus ATCC 29213 (MK5E). We could also demonstrate that c-WWW and c-WFW were effective against bacterial growth in liquid preserved boar semen in situ, especially when combined with a small amount of gentamicin. Our results suggest that albeit not offering a complete alternative to traditional antibiotics, the use of AMPs offers a promising solution to decrease the use of conventional antibiotics and thereby limit the selection of multi-resistant strains.
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Speck
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Courtiol
authors.affiliation: Leibniz Institute of Molecular Pharmacology, Berlin, Germany.
authors.forename: Christof
authors.initials: C
authors.lastname: Junkes
authors.affiliation: Leibniz Institute of Molecular Pharmacology, Berlin, Germany.
authors.forename: Margitta
authors.initials: M
authors.lastname: Dathe
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Müller
authors.affiliation: Institute for Reproduction of Farm Animals Schoenow e. V., Bernau, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schulze
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D004359:Drug Therapy, Combination; D005839:Gentamicins / Q000494:pharmacology; D008297:Male; D008826:Microbial Sensitivity Tests; D012661:Semen / Q000187:drug effects / Q000382:microbiology*; D012662:Semen Preservation / Q000379:methods*; D013552:Swine
chemical_list: D023181:Antimicrobial Cationic Peptides; D005839:Gentamicins