title: Mucin Binding Reduces Colistin Antimicrobial Activity.
abstract: Colistin has found increasing use in treating drug-resistant bacterial lung infections, but potential interactions with pulmonary biomolecules have not been investigated. We postulated that colistin, like aminoglycoside antibiotics, may bind to secretory mucin in sputum or epithelial mucin that lines airways, reducing free drug levels. To test this hypothesis, we measured binding of colistin and other antibiotics to porcine mucin, a family of densely glycosylated proteins used as a surrogate for human sputum and airway mucin. Antibiotics were incubated in dialysis tubing with or without mucin, and concentrations of unbound antibiotics able to penetrate the dialysis tubing were measured over time using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The percentage of antibiotic measured in the dialysate after 4 h in the presence of mucin, relative to the amount without mucin, was 15% for colistin, 16% for polymyxin B, 19% for tobramycin, 52% for ciprofloxacin, and 78% for daptomycin. Antibiotics with the strongest mucin binding had an overall polybasic positive charge, whereas those with comparatively little binding were less basic. When comparing MICs measured with or without added mucin, colistin and polymyxin B showed >100-fold increases in MICs for multiple Gram-negative bacteria. Preclinical evaluation of mucin binding should become a standard procedure when considering the potential pulmonary use of new or existing antibiotics, particularly those with a polybasic overall charge. In the airways, mucin binding may reduce the antibacterial efficacy of inhaled or intravenously administered colistin, and the presence of sub-MIC effective antibiotic concentrations could result in the development of antibiotic resistance.
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia.
authors.forename: Johnny X
authors.initials: JX
authors.lastname: Huang
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia.
authors.forename: Mark A T
authors.initials: MA
authors.lastname: Blaskovich
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia.
authors.forename: Ruby
authors.initials: R
authors.lastname: Pelingon
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia.
authors.forename: Soumya
authors.initials: S
authors.lastname: Ramu
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia.
authors.forename: Angela
authors.initials: A
authors.lastname: Kavanagh
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia.
authors.forename: Alysha G
authors.initials: AG
authors.lastname: Elliott
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Butler
authors.affiliation: Cardeas Pharma, Seattle, Washington, USA bruce.montgomery@cardeaspharma.com m.cooper@uq.edu.au.
authors.forename: A Bruce
authors.initials: AB
authors.lastname: Montgomery
authors.affiliation: Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Brisbane, Australia bruce.montgomery@cardeaspharma.com m.cooper@uq.edu.au.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Cooper
mesh_terms: D040981:Acinetobacter baumannii / Q000187:drug effects / Q000254:growth & development; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000378:metabolism / Q000494:pharmacology; D003091:Colistin / Q000378:metabolism / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry / Q000494:pharmacology*; D017576:Daptomycin / Q000378:metabolism / Q000494:pharmacology; D003956:Dialysis; D015314:Dialysis Solutions / Q000737:chemistry; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000254:growth & development; D008826:Microbial Sensitivity Tests; D009077:Mucins / Q000378:metabolism*; D011112:Polymyxin B / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D013552:Swine; D014031:Tobramycin / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D003470:Culture Media; D015314:Dialysis Solutions; D009077:Mucins; D002939:Ciprofloxacin; D011112:Polymyxin B; D017576:Daptomycin; D014031:Tobramycin; D003091:Colistin