Antimicrobial drugs c7

Sterilization

The complete removal or destruction of all living microorganisms, including endospores, which are the most resistant forms of life.

Commercial sterilization

Application of just enough heat to destroy Clostridium botulinum endospores (the ones that cause botulism) in canned foods.

Disinfection消毒

The destruction of vegetative (non-spore-forming) pathogens on inanimate (non-living) surfaces.

It does not necessarily kill all microbes, but it reduces them to a safe level.

Examples of disinfectants:

Bleach (sodium hypochlorite)

Alcohol (ethanol, isopropanol)

Lysol (phenolic compounds)

✅ Used for: Cleaning floors, tables, hospital equipment, etc.

Antisepsis

applied on living tissues (like skin or wounds).

Iodine solution

Hydrogen peroxide

Alcohol-based hand sanitizer

除菌degerming

Remove microbes temporary 

Wash hand with soap, alcohol swab before vaccine

Sanitization 卫生处理

Reduce number of microbes to a safe level

Wash dishes, treating water in pools

Penicillin

Cephalosporin

Polypeptide antibiotics

Bacitracin and vancomycin

Antimycobacterial agent de example

Isoniazid

Chloramphenicol

50s

Amino glycosidase

Streptomycin and gentamicin

30s

Tetracycline

30s

Lipopeptide de example

Daptomycin

Inhibit plasma membrane synthesis

Rifampin

Inhibit nuclei acid synthesis

(Inhibit mRNA synthesis in mycobacteria)

Quinolones and fluroqi no olones

Nalidixic acid and ciprofloxacin

Polyenes de example

Amphotericin B

Ergosterol

Pores

Leakage

Azoles de examples

Imidazole (for external mycoses)and triazoles(for internal mycoses)

Allylamines

Echinocandins

Prevent fungal Cell wall synthesis

Beta glucan

Flucytosine

Affect nucleic acid of fungal DNA RNA

Flucytosine enters fungal cells and is converted by fungal enzymes into 5-fluorouracil (5-FU).

5-FU gets incorporated into fungal RNA → disrupts protein synthesis.

Also inhibits enzymes for DNA synthesis, preventing replication.

Why it’s safe for humans:

Human cells lack the enzyme to convert flucytosine into 5-FU, so our cells aren’t harmed.

Antiprotozoal agents

1. Quinine

Inside infected red blood cells, Plasmodium parasites feed on hemoglobin (Hb) for nutrients.

When hemoglobin is broken down, it produces toxic heme (a chemical containing iron).

Normally, the parasite neutralizes the toxic heme by converting it into a harmless, crystal-like substance called hemozoin through a process called polymerization.

Quinine blocks this polymerization process:

Quinine binds to heme → prevents conversion to hemozoin.

Free heme accumulates inside the parasite.

Free heme is toxic and damages parasite membranes and enzymes.

The parasite dies.

2. Metronidazole and tinidazole

 Inside anaerobic protozoa, there is a special enzyme called ferredoxin oxidoreductase (PFOR).

This enzyme helps in energy production under low-oxygen (anaerobic) conditions.

Metronidazole and tinidazole act as "false targets" for this enzyme.

When PFOR acts on the drug, it reduces (activates) it by adding electrons to it.

Once reduced, the drug becomes chemically reactive and forms toxic radicals such as superoxide anions (O₂⁻) and free radicals.

These reactive molecules:

Damage the parasite’s DNA (causing breaks and mutations).

Inhibit nucleic acid synthesis (stops replication and transcription).