Intravenous and aerosolized polymyxins are being used increasingly, especially in the critical care setting, for treating patients with infections due to multidrug-resistant Gram-negative bacteria, mainly Acinetobacter baumannii and Pseudomonas aeruginosa. Recent literature suggests that intravenous colistin and polymyxin B have acceptable effectiveness for the treatment of patients with bacter...

For infections with antibiotic-susceptible strains of Pseudomonas aeruginosa, most studies have suggested that combination therapy, usually with a beta -lactam antibiotic plus an aminoglycoside, is preferable for patients with bacteremia and neutropenia. Against infections with Pseudomonas aeruginosa or Acinetobacter baumannii isolates that are resistant to all antibiotics except the polymyxins...

Polymyxin B and colistin (polymyxin E) are bactericidal pentacationic lipopeptides that act specifically on Gram-negative bacteria, first by disrupting their outermost permeability barrier, the outer membrane (OM), and then damaging the cytoplasmic membrane. Both were discovered in the mid-1950s and subsequently used in intravenous therapy, but soon largely abandoned because of nephrotoxicity. ...

Staphylococcus aureus is intrinsically resistant to polymyxins (polymyxin B and colistin), an important class of cationic antimicrobial peptides used in treatment of Gram-negative bacterial infections. To understand the mechanisms underlying intrinsic polymyxin resistance in S. aureus, we screened the Nebraska Transposon Mutant Library established in S. aureus strain JE2 for increased susceptib...

In recent years, carbapenem-resistant Enterobacteriaceae has become endemic in many countries. Because of limited treatment options, the abandoned "old antibiotics", polymyxins, have been reintroduced to the clinic. To evaluate the clinical efficacy of polymyxins in the treatment of infections caused by carbapenem-resistant Enterobacteriaceae, we systemically searched the PubMed, Embase, and Co...

Although the value of polymyxins B and E in the treatment of infections with Gram-negative bacilli is well recognized, they are not usually used unless the causal organisms are insensitive to antibiotics with wider activity. In consequence, sensitivity tests for them are not common laboratory procedures and it is not generally appreciated that the usual methods are not entirely satisfactory. Ju...