Polymyxins


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Related to Polymyxins: colistin, Sulfonamides, Polyenes

Polymyxins

 

a group of polypeptide antibiotics, or acylcy-clopeptides, produced by certain strains of bacilli, primarily Bacillus polymyxa. The molecules of most polymyxins contain residues of threonine, lucine, α,γ-diaminobutyric acid, and 6-methyloctanoic acid.

Polymyxins are active only against gram-negative bacteria such as Pseudomonas aeruginosa, dysentery causative agent, Escherichia coli, Salmonellae, and Klebsiellae. The antimicrobial mechanism in polymyxins is associated with damage to the membrane of the bacterial cell. Polymyxins are differentiated by their nature and by the intensity of their side effects, which are chiefly neurotoxic and nephrotoxic and which restrict their use. Polymyxins B, M, and E (colistin) are used in medical practice.

References in periodicals archive ?
M2 EQUITYBITES-March 6, 2018-MicuRx awarded CARB-X's grant for innovative polymyxin antibiotic MRX-8
All the isolates of Psuedomonas aeruginosa (n=5) were resistant to Ciprofloxacin but sensitive to Polymyxin B.
The following antibiotics were included: amoxicillin, amoxicillin-clavulanic acid (AMC), piperacillin, piperacillin-tazobactam (TZP), mezlocillin, mezlocillin-sulbactam (MSU), cefazolin, cefuroxime, ceftriaxone, cefotaxime, ceftazidime, cefoperazone, cefoperazone-sulbactam (CSL), cefepime, aztreonam, moxalactam, imipenem, meropenem, panipenem, ertapenem, gentamycin, amikacin, tetracycline, minocycline, tigecycline, ciprofloxacin, levofloxacin, nitrofurantoin, fosfomycin, polymyxin B, and colistin.
The most common successful regimen for treating pulmonary infections consisted of tigecycline plus colistin (8 patients), followed by aminoglycoside plus colistin (3 patients), but the overall failure rates were not significantly different in the three most commonly used antibiotic combinations: polymyxin plus carbapenem, polymyxin plus tigecycline, polymyxin plus aminoglycoside (30%, 29%, and 25%, respectively, p = 0.
Higher incidence of acute kidney injury with intravenous colistimethate sodium compared with polymyxin B in critically ill patients at a tertiary care medical center.
Minimum inhibitory concentrations (MIC) for polymyxin B were determined by E-tests, based on manufacturer's instructions (AB Biodisk, Solna Sweden).
Following antibiotic discs were put up with the concentration of the compound mentioned in the parenthesis: ceftazidime (30[micro]g), cefepime (30[micro]g), ceftriaxone (30[micro]g), cefotaxime (30[micro]g), amoxycillin/clavulanic acid (20[micro]g/10[micro]g), piperacillin/tazobactam (100[micro]g/10[micro]g), ticarcillin/clavulanic acid (75[micro]g/10[micro]g), imipenem (10[micro]g), meropenem (10[micro]g), gentamicin (10[micro]g), amikacin (30[micro]g), netilmicin (30[micro]g), ciprofloxacin (5[micro]g), doxycycline (30[micro]g), cotrimoxazole (15[micro]g), polymyxin B (300 units), colistin (10[micro]g), cefoperazone/sulbactam (75[micro]g/15[micro]g), ceftriaxone/sulbactam (30[micro]g/15[micro]g).
Just 60% of respondents said polymyxins were available in their hospitals, and only a quarter said they were on formulary.
Antimicrobial susceptibility against polymyxin B, Tigecycline and Fosfomycin was done by Kirby-Bauer disc diffusion method using disc polymyxin B 300 units, Tigecycline 15ug and Fosfomycin 200ug.
11) The confirmatory susceptibility test was performed using the agar dilution method for imipenem, tigecycline, and polymyxin B, as recommended by the Clinical and Laboratory Standards Institute and the Food and Drug Administration (FDA).
Because these bacteria usually remain susceptible to polymyxins, an old class of antimicrobial drugs almost abandoned in the 1970s because of their potential toxicity, interest in polymyxins (colistin and polymyxin B) has been renewed worldwide (1,2).
The discovery was described as "alarming" by scientists, who called for urgent restrictions on the use of polymyxins -- a class of antibiotics that includes the drug colistin and is widely used in livestock farming.