Chicken Cathelicidins Display Antimicrobial Activity against Multiresistant Bacteria without Inducing Strong Resistance

The increased prevalence of multidrug-resistant (MDR) bacteria in combination with the relatively limited development of
new antibiotics presents a serious threat to public health. In chicken, especially Extended-Spectrum ß-Lactamase (ESBL)
carrying Enterobacteriaceae are often asymptomatically present but can infect humans. Due to their broad range
antimicrobial activity cathelicidins and other host defence peptides, are considered to be an attractive alternative to
conventional antibiotics. In this study, the antimicrobial activity of three chicken cathelicidins against a broad array of
multidrug resistant bacteria was determined. All three peptides showed high antibacterial activity independent of the
presence of MDR characteristics. Induction experiments using S. aureus and K. pneumoniae showed that although an
increase in resistance was initially observed, susceptibility towards chicken cathelicidins remained high and no major
resistance was developed. The combined results underline the potential of chicken cathelicidins as a new alternative to
antibiotics.