Fusafungine, also known as fusafungin, is a cyclic depsipeptide antibiotic from Fusarium lateririum used for the treatment of nasal and throat infection including sinusitis, rhinitis, rhinopharyngitis, angina, laryngitis, and tracheitis. Fusafungine consists of a mixture of enniatins and has been widely used over the past 50 years. Its first authorization in the EU was in 1963. Fusafungine showed bacteriostatic activity against a suite of microorganisms, such as Mycoplasma pneumoniae, Legionella pneumophila, Streptococcus pneumoniae, S. pyogenes, and Staphylococcus aureus, including methicillin-resistant S. aureus. Besides its bacteriostatic activity against most micro-organisms involved in respiratory tract infections fusafungine displays original anti-inflammatory properties. Fusafungine has multiple mechanisms of action, including downregulation of the expression of intercellular adhesion molecule-1 (ICAM-1) and inhibition of production of proinflammatory cytokines. In September 2015, an EU-wide assessment of the benefit-risk of fusafungine was initiated due to an increase in the reporting rate of serious allergic reactions. European Medicines Agency (EMA) Pharmacovigilance Risk Assessment Committee (PRAC) recommended that fusafungine should be withdrawn from the EU market

Butirosin is water-soluble aminoglycosidic antibiotic complex which is active against both Gram-positive and Gram-negative bacteria. Butirosin is less toxic than neomycin and shows a good antibacterial activity, including Pseudomonas aeruginosa, which is resistant to neomycin, ribostamycin and kanamycin.

Colistin sulfate is a polypeptide antibiotic which penetrates into and disrupts the bacterial cell membrane. It is a cyclic polypeptide antibiotic from Bacillus colistinus. It is composed of Polymyxins E1 and E2 (or Colistins A, B, and C). Colistin was first isolated in Japan in 1949 from a flask of fermenting Bacillus polymyxa var. colistinus and became available for clinical use in 1959. The following local adverse events have been reported with topical corticosteroids, especially under occlusive dressings: burning, itching, irritation, dryness, folliculitis, hypertrichosis, etc. Healthcare providers had largely stopped using colistin in the 1970s because of its toxicity. However, with antibacterial resistance on the rise, colistin is increasingly being used today to treat severe, multidrug-resistant Gram-negative bacterial infections, particularly among intensive care-based patients. The problem with re-introducing an older drug, such as colistin, though, is that techniques for evaluating new drugs have evolved since the 1950s, and therefore, little is known about the dose needed to effectively fight infection while limiting the potential emergence of antimicrobial resistance and reducing potentially toxic side effects. More data are needed to guide optimal use of these older medications. An international team of NIAID-funded researchers is making progress in obtaining better dosing information about colistin and how best to use the antibiotic to treat Gram-negative bacterial infections. Resistance to colistin is rare. The first colistin-resistance gene that is carried in a plasmid and can be transferred between bacterial strains was described in 2016. This plasmid-borne mcr-1 gene has since been isolated in China, Europeand the United States.

Colistimethate is a methanesulfonate of polymyxin antibacterial colistin. Colistimethate is a nonactive prodrug. In aqueous solutions, colistimethate is hydrolyzed and forms a complex mixture of partially sulfomethylated derivatives and colistin. The antimicrobial activity of colistin is similar to that of polymyxin B and is restricted to gram-negative bacteria, including P aeruginosa, Acinetobacter species, Enterobacter-Klebsiella tribe, Escherichia coli, Salmonella and Shigella species, Citrobacter species, Yersinia pseudotuberculosis, Morganella morganii and Haemophilus influenzae. Colistin has also been shown to possess considerable in vitro activity against Stenotrophomonas maltophilia. Colistin and polymyxin B, however, do not have activity against Proteus, Providencia, Serratia species, Pseudomonas mallei, Burkholderia cepacia, Brucella species, most gram-positive bacteria, gram-negative cocci, anaerobes, fungi and parasites. Parenteral or nebulized colistimethate is indicated for the treatment of acute or chronic infections due to sensitive strains of certain gram-negative bacilli. It is particularly indicated when the infection is caused by sensitive strains of Pseudomonas aeruginosa.