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Terms in this set (32)
Fungus that causes local infection (thrush), GI infection and can become systemic (lethal)
Why might candida cause serious problems in immuno-compromised people?
It can become filamentous and may go through gut wall
What do fungi use instead of cholesterol in their cell membrane, enabling selectivity?
Examples of polyenes
Action of polyenes
Bind sterols within fungal membrane, most effective against yeasts
Can you use polyenes systemically?
No, not soluble
Carbon rich insoluble polyene
Action of azoles
Interfere with demethylation of lanosterol and therefore diminishes ergosterol production
Example of azole that is insoluble and not systemically used
Fluorine derivative azole which can be used systemically
Fluconazole, sold as "Diflucan"
Action of allylamines
Act to inhibit the synthesis of Lanosterol
Can allylamines be used systemically?
Allylamine that has already gained resistance and so needs to be used in combination therapy with Flucytosine
Action of 5-Fluorocytosine
Incorporates into RNA where it interferes with transcription/translation
What are the problems with antivirals?
Viral metabolism is closely linked to the host cell and there is difficulty in diagnosing the infection before it is too late
Antiviral used as treatment for cold sores (herpes simplex)
What does Acyclovir require to be active?
Needs to be triply-phophorylated
Why do only infected cells contain active acyclovir species?
Because the first phosphate group is incorporated by a viral thymidine kinase and not by host cell enzymes
Two ways in which acyclovir triphosphate works
Causing DNA termination, directly inhibiting viral DNA polymerase
How does Acyclovir cause DNA termination?
Incorporated into nucleic acid, Acyclovir contains has missing OH group on 3' where DNA replication would occur from, is a guanosine analogue
Guanosine analogue that is used in HIV/AIDS therapy
Reason for specificity of AZT
Phosphorylated derivative has high affinity for reverse transcriptase, causing chain termination and directly inhibiting enzyme
Action of amantadine
Inhibits uncoating in influenza A virus by interfering with a viral protein
Action of Relenza/Tamiflu
Virus particles associate with sialic acid residues on the cell. Compounds inhibit Neuraminidase enzyme, therefore virus particles can't leave cell surface and also aggregate
Antiviral made in Cardiff that is used to treat HIV/AIDS
Action of invirase
Inhibits HIV protease
Proteins made and released by host cells in response to presence of pathogens
Actions of interferons
Increase ribonuclease production, inhibit protein production
Problem with interferons
Novel antibiotics developed to inhibit ribosomal initiation step
Action of antimicrobial peptides
Interact with membrane to pop bacterial cells
Antimicrobial peptide now in use
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