title: Effect of antimicrobial peptides on colistin-susceptible and colistin-resistant strains of Klebsiella pneumoniae and Enterobacter asburiae.
abstract: In this study susceptibility to different antimicrobial peptides was investigated on colistin-susceptible and colistin-resistant identical pulsotype strains of KPC-2 producing Klebsiella pneumoniae ST258 as well as colistin-susceptible and colistin-resistant Enterobacter asburiae strains isolated from clinical samples. In our test, bacteria were exposed to 50 mg/ml lactoferrin, lysozyme and protamine - cationic antimicrobial peptides belonging to innate immune system and having structural similarity to polymyxins - in separate reactions. After 18 hours incubation of colonies were counted. 40% of colistin-resistant K. pneumoniae strains and 97% of colistin-susceptible counterpart strains were lysed by protamine whereas 87% and 100% colony forming unit decrease by lysozyme was seen, respectively. In the case of colistin-resistant E. asburiae strains 1 log10 cell count increase were observed after treatment with lysozyme and 1.56 log10 after lactoferrin exposure compared to the initial number whereas the colistin-susceptible showed no relevant cell count increase. Our findings suggest that acquired colistin-resistance in Enterobacteriaceae is associated with tolerance against antimicrobial peptides.
authors.affiliation: Institute of Medical Microbiology, Semmelweis University , Budapest , Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Kádár
authors.affiliation: Institute of Medical Microbiology, Semmelweis University , Budapest , Hungary.
authors.forename: Béla
authors.initials: B
authors.lastname: Kocsis
authors.affiliation: Institute of Laboratory Medicine, Diagnostic Laboratory of Clinical Microbiology , Budapest , Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Kristof
authors.affiliation: National Center for Epidemiology, , Budapest , Hungary.|European Program for Public Health Microbiology Training (EUPHEM), European Centre for Disease Prevention and Control (ECDC) , Stockholm , Sweden.
authors.forename: Ákos
authors.initials: Á
authors.lastname: Tóth
authors.affiliation: Institute of Medical Microbiology, Semmelweis University , Budapest , Hungary.
authors.forename: Dóra
authors.initials: D
authors.lastname: Szabó
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D003091:Colistin / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D004754:Enterobacter / Q000187:drug effects* / Q000254:growth & development; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000254:growth & development; D008826:Microbial Sensitivity Tests
chemical_list: D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D003091:Colistin
keywords: Enterobacteriaceae; antibiotic-resistance; antimicrobial peptides; colistin