Chapter 20: Antimicrobial Drugs Flashcards
What is the difference between an antibiotic and an antimicrobial agent?
An antibiotic is a substance produced wholly by microorganisms that, in small amounts, inhibits other microorganisms.
What is the difference between broad and narrow spectrum antibiotics?
Narrow spectrum has a small range of microbial types that they affect. Broad spectrum antibiotic affect an expansive range of Gram+ and Gram - bacteria.
When the identity of a pathogen isnt known, a broad spectrum wntibiotic would be advantageous. The disadvantage is that these drugs can destroy much of the natural flor in the body as well. Knowing the identity of the pathogen allows for better selection of a narrow spectrum antibiotic.
What are the 5 major modes of antibacterial drugs?
Inhibition of cell wall, inhibition of protein symnthesis, injury to plasma membrane, inhibition of nucleic acid synthesis, competitive inhibition of metabolite synthesis
Inhibiting cell wall synthesis prevents synthesis of intact peptidoglycan. What are the examples of this type of drug?
Penicillin family, cephalosporin family, polypeptide antibiotics like bacitracin and vancomycin.
Examples of drugs that fall under inhibition of protein synthesis
chloramphenicol, aminoglycosides (streptomycin), tertacyclines (very broad), spectrum macrolides (erythromycin), new generation (streptogramins, oxazolidinones)
Examples of drugs that injure the plasma membrane
polymyxin B, triclosan
Examples of drugs that fall under nucleic acid synthesis
rifamycin, fluoroquinolones, ciproflaxin
Examples of drugs that fall under inhibition of metabolite synthesis
sulfa family
What do sulfa drugs look like to microbes?
Para-aminobenzoic acid.
Issues with natural penicillins
They are narrow spectrum and rapidly excreted from the body in 3 to 6 hours, and are susceptible to penicillinases that cleave the beta lactam ring of the antibiotic.
How have semisynthetic penicillinases overcome some of the issues with natural penicillins
They have been made to be extended spectrum, and resistant to some penicillinases
What are several pathways in fungi that can be inhibited by antifungal drugs
Injury to plasma membrane, inhibiting synthesis of plasma membrane, inhibiting synthesis of cell wall, inhibits synthesis of RNA (protein synthesis), mitotic microtubules inhibited
Why have those that are effective antifungals become so important recently?
Fungal infections are becoming more frequent because of their role as opportunistic infections in immunosuppressed individuals, especially those with AIDS
What are two categories of antiviral agents?
Chemical inhibition and Interferon
Developing new antimicrobial agents?
continue search, modify current drugs, search other organisms, phage therapy, DNA/RNA manipulations
