title: Oxygen deprivation affects the antimicrobial action of LL-37 as determined by microplate real-time kinetic measurements under anaerobic conditions.
abstract: Some agents, including Escherichia coli and group A Streptococcus pyogenes cause infections in oxygen depleted sites. LL-37 is a human host defence peptide shown previously to play an important role in controlling infections caused by these bacteria. However, the effect of oxygen levels on the antimicrobial activity of LL-37 remains obscure. In order to test the effect of oxygen (or lack thereof) on LL-37's activity against E. coli and S. pyogenes, a method for adapting commonly used microtiter plates for real-time growth-kinetic (and growth-inhibition) measurements under anaerobic conditions was developed. Using the proposed method, anaerobic conditions were attained in the microplate within 30 min and were maintained for at least five days. Anaerobiosis was further confirmed by comparing the growth of two anaerobic oral species (Porphyromonas gingivalis and Fusobacterium nucleatum) in anaerobic compartments of microtiter plates versus aerobic ones. Both species grew only in the anaerobic compartments of the plates as indicated by the growth curves generated. The sensitivities of E. coli and S. pyogenes to LL-37 were tested under anaerobic conditions and compared to those in aerobic ones. The oxygen facultative E. coli grew to a higher density under aerobic conditions and its sensitivity to LL-37 was increased under anaerobiosis. The microaerophilic pathogen S. pyogenes grew faster and to a higher density under anaerobic conditions and was much more resistant to LL-37 under oxygen deprivation. Our results suggest that resistance to antimicrobial agents of microbes infecting anaerobic-microaerophilic sites should be tested under oxygen-restricted conditions.
authors.affiliation: Institute of Dental Sciences, The Hebrew University-Hadassah School of Dental Medicine, The Hebrew University of Jerusalem, P.O.B 12272, Jerusalem 91120, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Eini
authors.forename: Asaf
authors.initials: A
authors.lastname: Sol
authors.forename: Shunit
authors.initials: S
authors.lastname: Coppenhagen-Glazer
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Skvirsky
authors.forename: Avi
authors.initials: A
authors.lastname: Zini
authors.forename: Gilad
authors.initials: G
authors.lastname: Bachrach
mesh_terms: D000693:Anaerobiosis; D000890:Anti-Infective Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000188:drug therapy* / Q000382:microbiology*; D016967:Fusobacterium nucleatum / Q000187:drug effects / Q000254:growth & development; D006801:Humans; D016966:Porphyromonas gingivalis / Q000187:drug effects / Q000254:growth & development; D013297:Streptococcus pyogenes / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*; D054804:Cathelicidins
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins
keywords: Anaerobic; Fusobacterium nucleatum; LL-37; Porphyromonas gingivalis