What are viruses?
Small obligate intracellular parasites (must reproduce w/i host cells).
How are viruses transmitted?
Enter host via inhalation, transplacentally, skin/mucous membrane innoculation. Can be transmitted through formites, droplet, or contact.
What are the steps of viral replication?
1) Fusion to host cell 2) enter host nucleus 3) Viron synthesis (DNA, RNA, and protein made), 4) Viron release
What are the cytopathic effects of viral infection?
Host cell death, continued cellular infection/spreading. May go dormant and reactivate, restarting the infection later. Can mutate DNA/RNA, making them malignant host cells (especially if oncogenic viruses like HPV). Hopefully, it will activate a healthy
What are some viral diseases?
Chicken pox/Shingles, Flu, Warts, Colds, HIV/AIDS, herpes, hepatitis, cytomegalovirus (CMV)
How do antiviral agents work?
Suppress/Kill viruses by destroying virons, inhibiting fusion, inhibiting replication.
What do antiviral agents have to do in order to affect viruses?
They must affect body cells in order to "find" the virus. They work by suppressing biochemical processes unique to viral replication.
The drug Amantadine (Symmetrel) is an antiviral. How does it work?
It boosts immune function. It triggers the release of DA, and can be used prophylactically and to treat against active Influenza A viruses. It can shorten the disease by 2 days if given within 2 days of the onset of symptoms.
What are the side effects of Amantadine?
Dizziness, nervousness, insomnia
The drug acyclovir (Zovirax) is an antiviral. How does it work?
Treats infections caused by herpes simplex and herpes zoster viruses. It prevents outbreaks and stops the spread of the virus.
What are the side effects of Acyclovir?
reversible nephrotoxicity, phlebitis.
Gangciclovir (Cytovene) is an antiviral. How does it work, and what is a SE?
Active against cytomegalovirus (CMV) retinitis. Can cause bone marrow suppression.
How do retroviruses replicate? Give an example of a retrovirus?
They must first transcribe its RNA into DNA, using the enzyme reverse transcriptase. HIV, which attacks CD4T cells.
What is the standard treatment for HIV?
3-4 drugs in a regimen called HAART (highly active antiretroviral therapy). Its aim is to decrease the viral load to undetectable levels, delaying/reversing loss of immune fn and preserving/prolonging life.
What are the cons of HAART treatment?
Very complex, expensive. Risk of toxicity, drug interactions, and resistance.
What are the three categories of antiretroviral drugs?
Reverse Transcriptase Inhibitors (RTI), Protease Inhibitors, and Fusion Inhibitors
How do Reverse Transcriptase Inhibitors work?
Block the activity of reverse transcriptase, which promotes the synthesis of new viral DNA molecules from the RNA of the parent virus.
What are the side effects of reverse transcriptase?
Fever, HA, Abnormal liver fn
How do protease Inhibitors work? SEs?
inhibit viral replication. Can cause kidney stones
How do Fusion Inhibitors work? SEs?
Inhibit virus from fusing to the host cell. Can cause pain, puritis, cysts, brusing. Increased risk of bacterial pneumonia.
What is the causative agent of TB?
Mycobacterium tuberculosis, an aerobic bacillus. Transmitted via droplet inhalation.
How long does therapy for TB long?
6-24 months.
What are the cons of some drugs used to treat TB?
Can interact with HIV agents (protease inhibitors) to decrease drug activity. May be enzyme induces, increases the metabolism of oral contraceptive, beta blockers, phenytoin.
How do first line antitubercular drugs work?
Antibiotics ctive against actively dividing bacilli. Used in combination to reduce resistance. Includes Isoniazide (INH) and Rifampin (Rifadin)
What are some side effects of first line antitubercular drugs?
Isoniazide: hepatotoxicity, neuropathy, CNS effects, aplastic anemia
Rifampin: P450 enzyme inducer, urine color (orange/brown)
How do second line antitubercular drugs work?
Broad Spectrum antibiotics, including Aminoglycosides and Fluroquinolones.
How do we treat multi-drug resistant TB?
Long treatment with second-line drugs. Ensure compliance.
What kind of infections do fungi and molds cause?
Mycotic infections. Transmitted through ingestion, inhalation, implantation in broken skin.
What makes some mycotic infections so serious?
Resistant to treatment, can be severe/lifethreatening in immunocompromised ppl. Can be superficial or become systemic.
What are some common fungal infections?
Vaginal candidiasis (yeast infection), athlete's foot, ring worm, onychoomycosis (nail infection that spreads to other toes, common in elderly).
What do we use to treat systemic micoses?
Broad spectrum antifungals (IV admin; renal toxicity, dysrythmia). Azole Family drugs (inhibit P450 enzymes).
WHat do we use to treat superficial micoses?
Azole Family drugs (redness, stinging [w/ topical application], GI distress [oral]). Broad Spectrum antifungals (burning, itching).