Tyrocidine

Tyrocidine is a cyclic decapeptide antibiotic that is produced by the bacteria Bacillus brevis. It was one of the first antibiotics to be discovered and is part of the tyrothricin complex, which also includes gramicidin. Tyrocidine has a broad spectrum of activity and is effective against many gram-positive and gram-negative bacteria.

History

Tyrocidine was discovered in 1939 by René Dubos, a French-American microbiologist. Dubos isolated the antibiotic from Bacillus brevis, a soil bacterium. This discovery marked a significant milestone in the history of antibiotics, as it was the first time that an antibiotic had been isolated from a soil microorganism.

Structure and Mechanism of Action

Tyrocidine is a cyclic decapeptide, which means it is composed of ten amino acids arranged in a cyclic structure. The amino acids are linked together by peptide bonds, forming a ring structure. This structure is crucial for the antibiotic activity of tyrocidine.

The mechanism of action of tyrocidine involves disrupting the bacterial cell membrane. The cyclic structure of tyrocidine allows it to insert itself into the bacterial cell membrane, creating pores that disrupt the membrane's integrity. This leads to leakage of cellular contents and ultimately cell death.

Medical Uses

Tyrocidine is used primarily as a topical antibiotic due to its toxicity when administered systemically. It is effective against a broad range of bacteria, including Staphylococcus aureus, Streptococcus pyogenes, and Pseudomonas aeruginosa. It is often used in combination with other antibiotics to increase its spectrum of activity.

Side Effects and Precautions

Due to its mechanism of action, tyrocidine can be toxic to human cells as well as bacterial cells. Therefore, it is primarily used as a topical treatment and is not suitable for systemic use. Side effects can include skin irritation and allergic reactions.

See Also

• Antibiotics
• Bacillus brevis
• René Dubos
• Tyrothricin

References

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