Polymyxin B1-I sulfate is one of the individual polypeptide components in polymyxin B sulfate. Polymyxin B1-I contains, among other amino acids, an L-isoleucine residue in place of the L-leucine reside found in the other polymyxin fractions. The unique fatty acid group found in B1-I is 6-methyloctanoic acid (6-MOA), the same group found in polymyxin B1. Results from in vitro studies have shown marginal differences in MIC data when comparing the fractions.
Kassamali, et al. used polymyxin B1, polymyxin B2, polymyxin B3, and polymyxin B1-I to test for synergistic and antagonistic effects against various Gram-negative organisms.
Read more here: "Microbiological Assessment of Polymyxin B Components Tested Alone and In Combination"
Lim et al. used polymyxin B1, B2, B3, and B1-I from TOKU-E to study the stability of each compound in saline, dextrose, and saline/dextrose infusion solutions. "Physicochemical stability study of polymyxin B in various infusion solutions for administration to critically Ill patients."
|Mechanism of Action||Polymyxin B targets and alters permeability lipopolysaccharide (LPS) of gram negative bacteria leading to lysing of the cell. Polymyxin B only needs to interact with LPS, it is not required to enter the cell.|
|Spectrum||Polymyxin B sulfate targets the outer membrane of gram negative bacteria especially Pseudomonas aeruginosa.|
Kassamali, et al. found polymyxin B3 to be the most active polymyxin fraction against most organisms in their experiment. Kassamali, et al. also discovered a synergistic effect using polymyxin B3 and B1-I against their tested organisms.
|Microbiology Applications||Polymyxin B sulfate is commonly used in clinical in vitro microbiological antimicrobial susceptibility tests (panels, discs, and MIC strips) against gram negative microbial isolates. Medical microbiologists use AST results to recommend antibiotic treatment options for infected patients. Representative MIC values include:|
|Plant Biology Applications||Polymyxin B sulfate was successfully tested to counteract phytopathogenic gram-negative bacterial growth including different strains of Pseudomonas viridiflava and Erwinia carotovora. Polymixin B sulfate was shown to reduce bacterial growth of different strains of Pseudomonas viridiflava at low concentrations, (0.08 µg/ml) and Erwinia carotovora growth at slightly higher concentrations (0.25 µg/ml) (Selim et al. 2005).|
|Molecular Formula||C56H98N16O13 • xH2O4S (lot specific)|
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|MIC||P. aeruginosa (ATCC 27853)| 4 |1666| A. baumannii (ATCC BAA 747)|1|1666| K. pneumoniae ATCC 13883|2|1666| P. aeruginosa (9019)|1|1666| A. baumannii (1261)|1|1666| K. pneumoniae (VM9)|1|1666||