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4

Polypeptide antibiotics disrupt bacterial cell walls (see Table 15: Bacteria and Antibacterial Drugs: Polypeptides).

Table 15
Polypeptides BacitracinSome Trade Names AK-TRACIN BACIGUENT BACIIM Click for Drug Monograph Colistin Polymyxin BSome Trade Names POLY-RX Click for Drug Monograph

BacitracinSome Trade Names
AK-TRACIN
BACIGUENT
BACIIM
Click for Drug Monograph
is a polypeptide antibiotic that inhibits cell wall synthesis and is active against gram-positive bacteria.

Colistin (polymyxin E) and polymyxin BSome Trade Names
POLY-RX
Click for Drug Monograph
are cationic polypeptide antibiotics that disrupt the outer bacterial cell membrane by binding to the anionic outer membrane, which contains lipopolysaccharide (endotoxin), and thereby neutralizing the bacteria's toxicity.

Colistin methane sulfonate (colistimethateSome Trade Names
COLY-MYCIN M
Click for Drug Monograph
sodium [CMS]) is a parenteral preparation of a prodrug that is transformed in blood and urine to colistin. CMS is less toxic than colistin.

Polypeptides are usually used topically; systemic absorption is negligible.

Indications

Polymyxin BSome Trade Names
POLY-RX
Click for Drug Monograph
and colistin have rapid concentration-dependent bactericidal activity against

• Most facultative and aerobic gram-negative bacilli, including Pseudomonas aeruginosa and Acinetobacter sp

These drugs are not active against Proteus, Providencia, Burkholderia, and Serratia spp and some obligate anaerobes, including Bacteroides fragilis and gram-positive bacteria. Development of resistance is uncommon.

Polypeptides are used for several types of infections (see Table 16: Bacteria and Antibacterial Drugs: Some Clinical Uses of Polypeptides).

Table 16
Some Clinical Uses of Polypeptides Preparation Uses Comments Combination treatments Ointment containing bacitracinSome Trade Names AK-TRACIN BACIGUENT BACIIM Click for Drug Monograph plus neomycinSome Trade Names NEO-FRADIN NEO-RX Click for Drug Monograph , polymyxin BSome Trade Names POLY-RX Click for Drug Monograph , or both Wound infection No confirmation of clinical efficacy Spray containing neomycinSome Trade Names NEO-FRADIN NEO-RX Click for Drug Monograph , bacitracinSome Trade Names AK-TRACIN BACIGUENT BACIIM Click for Drug Monograph , and polymyxin Prevention of postoperative wound infections Appears to help Polymyxin BSome Trade Names POLY-RX Click for Drug Monograph ophthalmic ointments and solutions with other antimicrobials (eg, bacitracinSome Trade Names AK-TRACIN BACIGUENT BACIIM Click for Drug Monograph , neomycinSome Trade Names NEO-FRADIN NEO-RX Click for Drug Monograph , trimethoprim/sulfamethoxazoleSome Trade Names BACTRIM SEPTRA Click for Drug Monograph ) and corticosteroids Ophthalmic use Significantly improved rates of early clinical remission (although acute bacterial conjunctivitis is frequently self-limited) Otic suspension with polymyxin BSome Trade Names POLY-RX Click for Drug Monograph , neomycinSome Trade Names NEO-FRADIN NEO-RX Click for Drug Monograph , and hydrocortisoneSome Trade Names CORTEF SOLU-CORTEF Click for Drug Monograph or with colistin, neomycinSome Trade Names NEO-FRADIN NEO-RX Click for Drug Monograph , and hydrocortisoneSome Trade Names CORTEF SOLU-CORTEF Click for Drug Monograph Otitis externa (commonly due to Pseudomonas aeruginosa) Clinically effective, but may be no more effective than 2% acetic acid with hydrocortisoneSome Trade Names CORTEF SOLU-CORTEF Click for Drug Monograph In patients with a tympanostomy tube or known perforation of the tympanic membrane, must use a nonototoxic topical preparation (no aminoglycoside or alcohol) BacitracinSome Trade Names AK-TRACIN BACIGUENT BACIIM Click for Drug Monograph Topical Eradication of Staphylococcus aureus nasal carriage Impetigo Less effective than other treatments Oral Clostridium difficile–induced diarrhea (pseudomembranous colitis) Less effective and less palatable than oral vancomycinSome Trade Names VANCOCIN Click for Drug Monograph or metronidazoleSome Trade Names FLAGYL Click for Drug Monograph Colistin Aerosolized colistin methane sulfonate (colistimethateSome Trade Names COLY-MYCIN M Click for Drug Monograph sodium [CMS]) Cystic fibrosis Occasionally hospital-acquired pneumonia caused by multidrug-resistant gram-negative bacilli Associated with fewer adverse effects (eg, chest tightness, throat irritation, cough) than colistin sulfate Aerosolized colistin sulfate Same as for aerosolized colistin methane sulfonate May be beneficial for patients with cystic fibrosis or nosocomial pneumonia (ventilator-associated or not) due to multidrug-resistant gram-negative bacteria Parenteral CMS Severe infections due to multidrug-resistant gram-negative bacilli such as P. aeruginosa or Acinetobacter sp Reduced dose in patients with renal insufficiency Polymyxin BSome Trade Names POLY-RX Click for Drug Monograph Solutions GU irrigation —

Contraindications

All polypeptides are contraindicated in patients who have had an allergic reaction to them. CMS and polymyxin BSome Trade Names
POLY-RX
Click for Drug Monograph
should not be given simultaneously with drugs that block neuromuscular transmission or are nephrotoxic (eg, aminoglycosides, curare-like drugs).

Use During Pregnancy and Breastfeeding

BacitracinSome Trade Names
AK-TRACIN
BACIGUENT
BACIIM
Click for Drug Monograph
may pose minimal risk during pregnancy and breastfeeding because systemic absorption is minimal; however, safety has not been established.

Polymyxin BSome Trade Names
POLY-RX
Click for Drug Monograph
is in pregnancy category B (animal studies show no risk and human evidence is incomplete, or animal studies show risk but human studies do not).

Colistin is in pregnancy category C (animal studies show some risk, evidence in human studies is inadequate, but clinical benefit sometimes outweighs risk); this drug crosses the placenta. Whether use during breastfeeding is safe is unknown.

Adverse Effects

Adverse effects include

• Nephrotoxicity
• Central and peripheral neurotoxicity

Polymyxins are nephrotoxic. CMS and polymyxin BSome Trade Names
POLY-RX
Click for Drug Monograph
may cause circumoral and extremity paresthesias, vertigo, slurred speech, and muscle weakness and respiratory difficulty due to neuromuscular blockade, especially in patients with renal insufficiency.

Last full review/revision July 2009 by Matthew E. Levison, MD

Content last modified July 2009