title: Differences in potency and categorical agreement between colistin and polymyxin B when testing 15,377 clinical strains collected worldwide.
abstract: Gram-negative bacilli (n=15,377) were tested against colistin (polymyxin E) and polymyxin B by a commercial broth microdilution method (Sensititre®). Among Pseudomonas aeruginosa and Acinetobacter spp., colistin and polymyxin B MIC values were within ±1 doubling dilution for >99.0% of strains. Among Klebsiella spp. and Escherichia coli, 55.0 and 53.2% of strains displayed a colistin MIC 2-fold lower than polymyxin B, but polymyxin B was slightly more potent than colistin against strains with decreased susceptibility to either polymyxin.
authors.affiliation: JMI Laboratories, North Liberty, IA, USA. Electronic address: helio-sader@jmilabs.com.
authors.forename: Helio S
authors.initials: HS
authors.lastname: Sader
authors.affiliation: JMI Laboratories, North Liberty, IA, USA.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Rhomberg
authors.affiliation: JMI Laboratories, North Liberty, IA, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Farrell
authors.affiliation: JMI Laboratories, North Liberty, IA, USA.
authors.forename: Ronald N
authors.initials: RN
authors.lastname: Jones
mesh_terms: D003091:Colistin / Q000494:pharmacology*; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D006801:Humans; D008826:Microbial Sensitivity Tests; D011112:Polymyxin B / Q000494:pharmacology*
chemical_list: D011112:Polymyxin B; D003091:Colistin
keywords: Broth microdilution method; Polymyxins; Susceptibility testing