title: Cholesterol enhances Helicobacter pylori resistance to antibiotics and LL-37.
abstract: The human gastric pathogen Helicobacter pylori steals host cholesterol, modifies it by glycosylation, and incorporates the glycosylated cholesterol onto its surface via a cholesterol glucosyltransferase, encoded by cgt. The impact of cholesterol on H. pylori antimicrobial resistance is unknown. H. pylori strain 26695 was cultured in Ham's F12 chemically defined medium in the presence or absence of cholesterol. The two cultures were subjected to overnight incubations with serial 2-fold dilutions of 12 antibiotics, six antifungals, and seven antimicrobial peptides (including LL-37 cathelicidin and human alpha and beta defensins). Of 25 agents tested, cholesterol-grown H. pylori cells were substantially more resistant (over 100-fold) to nine agents than were H. pylori cells grown without cholesterol. These nine agents included eight antibiotics and LL-37. H. pylori was susceptible to the antifungal drug pimaricin regardless of cholesterol presence in the culture medium. A cgt mutant retained cholesterol-dependent resistance to most antimicrobials but displayed increased susceptibility to colistin, suggesting an involvement of lipid A. Mutation of lpxE, encoding lipid A1-phosphatase, led to loss of cholesterol-dependent resistance to polymyxin B and colistin but not other antimicrobials tested. The cgt mutant was severely attenuated in gerbils, indicating that glycosylation is essential in vivo. These findings suggest that cholesterol plays a vital role in virulence and contributes to the intrinsic antibiotic resistance of H. pylori.
authors.affiliation: Department of Microbiology and Immunology MSB 2-225, Louisiana State University Health Sciences Center-Shreveport, 1501 Kings Highway, Shreveport, LA 71130, USA. dmcgee@lsuhsc.edu
authors.forename: David J
authors.initials: DJ
authors.lastname: McGee
authors.forename: Alika E
authors.initials: AE
authors.lastname: George
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Trainor
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Horton
authors.forename: Ellen
authors.initials: E
authors.lastname: Hildebrandt
authors.forename: Traci L
authors.initials: TL
authors.lastname: Testerman
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000502:physiology; D001729:Bismuth / Q000494:pharmacology; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D002784:Cholesterol / Q000494:pharmacology*; D004261:DNA Replication / Q000187:drug effects; D024881:Drug Resistance, Bacterial; D005492:Folic Acid / Q000378:metabolism; D016480:Helicobacter pylori / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008050:Lipid A / Q000378:metabolism; D020559:Monomeric GTP-Binding Proteins / Q000502:physiology; D009942:Organometallic Compounds / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012459:Salicylates / Q000494:pharmacology; D054804:Cathelicidins
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D008050:Lipid A; D009942:Organometallic Compounds; D011500:Protein Synthesis Inhibitors; D012459:Salicylates; C015715:bismuth subsalicylate; D005492:Folic Acid; D002784:Cholesterol; D010744:Phosphoric Monoester Hydrolases; C108621:CgtA protein, bacteria; D020559:Monomeric GTP-Binding Proteins; D001729:Bismuth; D054804:Cathelicidins