Polypeptides Antibiotics destroy bacterial cell walls (see table: polypeptides). Polypeptides Bacitracin Colistin Polymyxin B Bacitracin is a polypeptide antibiotic which inhibits cell wall synthesis, and is effective against gram-positive bacteria. Colistin (polymyxin E) and polymyxin B are cationic polypeptide antibiotics which disrupt the outer cell membrane bacteria by binding to the anionic outer membrane and thereby neutralize the toxicity of the bacteria and cause bacterial cell death. Colistin methanesulfonate (Colistinmethate sodium [CMS]) is a parenteral prodrug which is converted in blood and urine to colistin. CMS is less toxic than colistin. Other polypeptides than colistin are usually applied topically; Systemic absorption is negligible. Indications polypeptides are used for different types of infections (see table: Some clinical applications of polypeptides). Bacitracin is mainly used as a topical treatment for superficial skin infections caused by Staphylococcus aureus polymyxin B and colistin have a rapid concentration-dependent bactericidal activity (efficacy) against Most facultative and aerobic gram-negative bacteria, including Pseudomonas aeruginosa and Acinetobacter sp These drugs are not effective against Proteus, Providencia, Burkholderia, and Serratia spp. as well as some obligate anaerobes, including Bacteroides fragilis and Gram-positive bacteria. Development of resistance is rare. The spread extensively drug-resistant gram-negative bacteria in hospitals has led to a resurgence of the use of i.v. Colistin in severe systemic infections (eg. As ventilator-associated pneumonia, bacteremia) out. However, should i.v. Polymyxin B and colistin are generally only used if no less toxic alternative exists. Some clinical applications of the polypeptides preparing applications Comments combination treatments with bacitracin ointment plus. Neomycin, polymyxin B, or both wound infection No confirmation from the spray clinical efficacy with neomycin, bacitracin and polymyxin prevention of surgical site infections probably effective Polymyxin B ophthalmic ointments and solutions with other antibiotics (eg. As bacitracin, neomycin, trimethoprim / sulfamethoxazole) and corticosteroids Ophthalmological application Significantly improved rates of early clinical remission (although an acute bacterial conjunctivitis often goes back on its own) ear drops with polymyxin B, neomycin and hydrocortisone or colistin, neomycin and hydrocortisone otitis externa ( are usually caused effectively by Pseudomonas aeruginosa) clinical, but probably not more effective than 2% acetic acid with hydrocortisone in patients with tympanostomy tube or a known perforation of the tympanic membrane must be a nichtototoxisches topical preparation used (no aminoglycoside or alcohol) Bacitracin Topical Nasal eradication of Staphylococcus aureus impetigo less effective than other treatments Oral Clostridium difficile-induced diarrhea (pseudomembranous colitis) Less take effective and more unpleasant than oral vancomycin or metronidazole colistin Aerosolized colistin methane sulfonate (colistimethate sodium [CMS]) Cystic fibrosis Occasionally in hospital-acquired Lung enentzündung caused by multidrug-resistant Gram-negative bacteria associated with fewer side effects (eg. As tightness in the chest, cough, cough) as colistin Aerosolized colistin As with aerosolized colistin methanesulfonate Also recommended for patients with cystic fibrosis or nosocomial pneumonia (ventilator-associated or not) by multidrug-resistant Gram-negative bacteria Parenteral CMS Severe infections caused by multi-resistant Gram-negative bacteria such as P. aeruginosa or Acinetobacter sp Reduced dose in patients with renal insufficiency polymyxin B Solutions urogenital-conditioners – All contraindications polypeptides are in patients who have had an allergic reaction to this, contraindicated. CMS and polymyxin B should not be administered concurrently with drugs that block neuromuscular transmission or nephrotoxic are (eg. As aminoglycosides, curare-like drugs). Use during pregnancy and lactation bacitracin may pose a minimal risk during pregnancy and lactation because systemic absorption is minimal only, but safety has not been established. Polymyxin B is in pregnancy category B (animal studies show no risk, human experience is incomplete or animal studies show risk, but human studies do not). Colistin is in pregnancy category C (animal studies show some risk indications in human studies are insufficient, but sometimes the clinical benefit outweighs the risk); This drug passes through the placenta. Whether the use during breastfeeding is safe is unknown. Side effects Side effects include nephrotoxicity Central and peripheral neurotoxicity polymyxins are nephrotoxic. CMS and polymyxin B can cause circumorale and Extremitätenparästhesien, dizziness, slurred speech and muscle weakness and shortness of breath due to neuromuscular blockade, especially in patients with renal insufficiency. Considerations Dosage Because colistin before the advent of modern pharmacokinetic / pharmacodynamic analysis was published, its appropriate dosage has not been studied as intensively as for many modern antibiotics. In addition, manufacturers use no standard way to describe the amount of substance; some use international units and other use-mg to the colistin base activity or mg details of the actual colistimethate. Whichever units are used, higher 1glauben many experts, that the recommended by the manufacturers dose of 2.5 to 5 mg / kg is too low the colistin base activity per day which is divided into 2 to 4 doses and recommend dosages, including the use of a higher dose. However, nephrotoxicity is dose-dependent and results in higher doses to larger concerns. The dosage should be discussed with an expert. 1Garonzik SM, et al: Population pharmacokinetic of colistin methanesulfonate and molded colistin in critically ill patients in a study in several medical institutions provide dosage recommendations for various categories of patients. Antimicrob Agents Chemother 55 (7): 3284-3294., 2011

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