Microbiology Antibiotics

Naturally occurring agents produced when cells are infected by virus. IFN-alpha and IFN-beta trigger nonspecific reaction. Uninfected cells make antiviral proteins to protect themselves.

• Various ones prevent virus by entering host cell.
• Example: amatadine prevents uncoating of Influenza A virus

• Various ones specific for select protease. Inhibits proper formation of "working" proteins.
• Viruses

• Binds to microtubules and prevents spindle apparatus formation-inhibitor of microtubules(mitosis).
• High penetration into keratin. Used for fungal infections of the skin, nails, ringworm, athletes foot.

• Inhibits DNA gyrase, the enzyme needed for uncoiling bacterial DNA so it can be replicated-inhibits nucleic acid synthesis
• example: ciprofloxacin (Cipro)

Binds to the enzyme RNA polymerase which is needed to synthesize RNA-inhibit nucleic acid synthesis

• Mimic the natural occurring nucleosides. mistakenly incorporated into DNA-inhibit nucleic acid synthesis
• Virus must be actively replicating

Blocks different reaction in folic acid synthesis-interuption of metabolic pathways

Competitively inhibits PABA needed for folic acid synthesis so organism cant make nucleic acids-interuption of metabolic pathways

A strand of nucleic acid complimentary to mRNA, blocks attachment of ribosomal subunits-inhibitor of protien synthesis

• Binds to 50S ribosome which blocks ribosome movement and prevents reading of mRNA-inhibitor of protien synthesis
• Examples include: erythromycin, azithromycin (zithromax) and clarithromycin (biaxin)

• Block the docking of the tRNA-AA to the A site of the 30S subunit-inhibitor of protien synthesis.
• Discoloration off teeth and stunts bone growth in young children.

• Blocks reading of mRNA by binding to 30S subunit of ribosome-inhibitor of protien synthesis.
• Poorly absorbed orally, given IV, narrow theraputic range, otic and nephrotoxic

• Prevents peptide bond formation between adjacent amino acids because binds to 50S subunit-inhibitors of protien synthesis
• In bone marrow prevents incorporation of hemoglobin into RBC=aplastic anemia

Change membrane permeability by inhibiting synthesis of ergosterol. Blocks the enzyme lanosterol a-demethylase-disrupts plasma membrane

• Attaches to ergosterol and changes membrane permeability by creating pores in the membrane-disrupts plasma membrane
• High concentration can target cholesterol in human cells leading to nephrotoxicity

• Changes membrane permeability by attaching to phospholipid (phosphatidylethanolamine) in the plasma membrane-disrupts plasma membrane
• Also targets eukaryotic cells and can cause nephrotoxicity

Inhibit synthesis of beta-glucan component of cell wall by inhibiting the enzyme 1,3 beta-glucan synthase-inhibits cell wall synthesis

• Forms a complex within bacteria that blocks the enzyme, fatty acid synthase. This prevents mycolic acid production-inhibits cell wall synthesis
• Drug of choice however used with other antimicrobials to prevent rapid resistance

• inhibits transport of NAG and NAM to PTG growing points outside of plasma membrane-inhibits cell wall
• Only used IV, Known as "mississippi mud" otic and nephrotoxicity

• Inhibits transport of NAM to cell wall by blocking the transporter, bactoprenol-inhibits cell wall synthesis
• Renal toxicity reatricts use to topical agents (triple antibiotic ointment)

• Competitvely blocks crosslinking of NAG/NAM subunits-inhibits cell wall
• Bacteria developed lactamases that destroy beta-lactam ring