The study tested five antimicrobial peptides on a range of oral bacteria and a fungus. Nisin was the strongest, stopping many common mouth microbes, while melittin and lactoferrin had limited effects. LL‑37, the peptide you asked about, showed no activity against any of the tested strains.

<b>Background</b>: Due to the increasing emergence of multi-resistant bacteria the search for alternative antimicrobial substances is of high interest. Promising agents are antimicrobial peptides which are host defense molecules of the innate immune system in a wide range of different species. <b>Objectives</b>: The aim of this study was to assess the activity of nisin, melittin, lactoferrin, parasin-1 and LL-37 against 35 oral bacteria and <i>Candida albicans</i> employing the gold standard method for anaerobic susceptibility testing. <b>Methods</b>: The activity of the peptides was determined by an agar dilution method under anaerobic and aerobic conditions. The test media contained final peptide concentrations between 0.125&#xa0;&#xb5;g/ml and 8&#xa0;&#xb5;g/ml (melittin, lactoferrin, parasin-1, LL-37) and between 0.125&#xa0;&#xb5;g/ml and 128&#xa0;&#xb5;g/ml (nisin). <b>Results</b>: Nisin completely inhibited the growth of <i>Megasphaera</i> sp., <i>Bifidobacterium longum, Parvimonas micra, Actinomyces israelii, Actinomyces naeslundii, Actinomyces odontolyticus, Prevotella intermedia, Streptococcus anginosus, Streptococcus constellatus</i> and <i>Staphylococcus aureus</i>. Melittin and lactoferrin reduced the growth of <i>Megasphaera</i> sp., <i>P. micra, B. longum</i> (melittin) and <i>Selenomonas flueggei</i> (lactoferrin). Parasin-1 and LL-37 showed no activity. <b>Conclusion</b>: AMPs, especially nisin and to a smaller degree lactoferrin, might be promising alternatives to antibiotics because of their antimicrobial activity, high resistance to environmental conditions and partially low costs.