Penicillin: Discovery, Mechanism, and Uses

Discovery and History

• Penicillin was discovered by Scottish scientist Alexander Fleming in 1928
• Fleming observed that a mold (Penicillium notatum) had contaminated one of his bacterial cultures, and that the mold had killed off the surrounding bacteria
• He isolated the substance responsible for this effect, which he named penicillin

Mechanism of Action

• Penicillin works by inhibiting the synthesis of the bacterial cell wall
• It does this by binding to and inhibiting the activity of an enzyme called DD-transpeptidase
• This prevents the bacteria from forming a rigid cell wall, ultimately leading to the death of the bacterial cell

Types of Penicillin

• Natural penicillins: derived from the Penicillium mold, these include penicillin G and penicillin V
• Semisynthetic penicillins: modified from natural penicillins, these include ampicillin and amoxicillin
• Synthetic penicillins: completely man-made, these include piperacillin and ticarcillin

Uses and Effects

• Penicillin is used to treat bacterial infections, including pneumonia, meningitis, and septicemia
• It is effective against a wide range of bacteria, including Staphylococcus, Streptococcus, and E. coli
• Common side effects of penicillin include allergic reactions, diarrhea, and nausea

Resistance and Limitations

• Overuse and misuse of penicillin has led to the development of antibiotic-resistant bacteria
• Penicillin is not effective against viral infections, fungal infections, or parasitic infections
• Patients with a history of allergies or asthma may be more likely to experience adverse reactions to penicillin