Anti-infective Drugs: Module 10 Flashcards
Drug classes in this category
Anti-microbial drugs include:
- Anti-bacterial’s (antibiotics) used for:
- Anti-virals used for:
- Anti-tubercular drugs used for:
- Anti-mycotics used for:
- Anti-bacterials are for bacterial infections
- Anti virals for infections
- Anti-tubercular for tuberculosis (TB)
- Anti-mycotics for fugal infections
When selecting Anti-microbials
- First:
- Then determine its susceptibility to various drugs with a?
- Consider location of?
- Consider drug?
- first isolate, identify micro-organism by growing a culture
- culture and sensitivity results take 48 hours
- Consider location of infections
- Consider drug cost, adverse effects, patient allergies.
Ideally, select agent after organism identified, drug sensitivity established.
- Treating presumptively if acutely ill, treat while wait for laboratory analysis
- Treat presumptively with:
If gram-positive only:
If gram-negative only:
If mixed:
If anaerobic only:
- treat presumptively, broad spectrum antibiotic (effective against gram-positive, gram-neg, and anaerobes)
- gram-pos: continue gram-positive coverage; discontinue gram-neg.
- gram-neg: continue gram-neg coverage; discontinue gram-pos, anaerobic coverage
- Mixed: continue therapy as initiated
- continue anaerobic only; discontinue gram-pos and neg coverage.
Antibiotics:
Narrow spectrum:
Broad spectrum
Antibiotics: substances derived from one living organism that can kill another organism; used systemically
-Narrow spectrum: act only on single or limited group of microorganisms
-Broad spectrum: affect wide variety of microbial species; more harmful to normal gut flora when taken long-term or repeatedly short-term
Medically important microorganisms
chlamydia spirochetes gram (+) cocci gram (-) Entric rods Other Gram (-) bacilli Gram (-) cocci Mycoplasma
Antibiotic Resistance
-Acquired resistance:
Causes
- Given unnecessarily:
- Over use:
- Broad versus narrow spectrum:
- Incomplete dosage taken:
-Acquired resistance: drug-resistant genes incorporated into bacteria genetic code with each new generation
- Given unnecessarily: upper respiratory infections
- Over use: low doses in animal feed
- Broad versus narrow spectrum: avoid wide spectrum, except in emergency situations
- Incomplete dosage taken: selects for resistant organisms
Antibiotic
-Bacteriostatic:
-Bactericidal:
- Bacteriostatic: temporarily inhibit bacterial growth, giving time for host’s immune system to respond
- Bactericidal: kill bacteria
Antibiotics Mechanisms
-Inhibit:
- Alter:
- Inhibit
-inhibit cell wall synthesis
- Alter membrane permeability or active transport mechanisms
- Inhibit protein synthesis: act on ribosomes
Antibiotic Classes
-Penicillins:
- Cephalosporins:
- Tetracyclines:
- Macrolides (Erythromycin)
- Carbapenems:
- Fluoroquinolones (Quinolones):
- Sulfonamides:
- Penicillins: bactericidal; inhibit cell wall synthesis; broad spectrum, beta-lactam molecular structure (penicillin G, amoxicillin
- Cephalosporins: bactericidal; inhibit cell wall synthesis; beta-lactam molecular structure; 4 generations [cefazolin, cefaclor, cefixime, cefepime]
Tetracyclines: bacteriostatic, inhibit protein synthesis; broad spectrum; 4-ring structure; originally isolated from Streptomyces aureofaciens; bind (chelate) divalent metals (Ca++, Zn++, Mg++) leading to teeth, bone discoloration; requires second form of birth control with use [doxycycline, tetracycline]
Macrolides: bacteriostatic; inhibit protein synthesis; broad spectrum; isolated from Streptomyces aureofaciens [erythromycin, azithromycin]
- Carbaenems: inhibit bacterial cell-wll synthesis; broadest spectrum available, used for life-threatening, nosocomial (hospital-acquired) infections [imipenem]
- Fluoroquinolones: bacteriocidal; interrupt DNA synthesis during replication [cliprofloxacin]
- Sulfonamides: bacteriostatic; inhibit folic acid production ➡ inhibits growth; require adequate fluid intake to prevent stone formation [sulfadiazine, sulfixoxazole]
Antibiotics
Cephalosporins incorporates itself?
-incorporates itself into cell wall
Inhibit cell wall synthesis
Daughter cells unable to close cell wall as result of cephalosporin leads to cell death
Antibiotics
Cephalosporins
- First-generation:
- Second-generation:
- Fourth-generation:
- First-generation: for gram-positive, staphylococcal, streptococcal infections; used for those allergic to penicillin
- Second-generation: for gram-negative, anaerobic infections
- Fourth-generation: for gram-positive, gram-negative infections.
Anti-viral Drugs
-Viruses:
- Respiratory infections:
- Herpes, Cytomegalovirus infections:
- HIV:
- Hepatitis, Leukemia, Kaposi’s Sarcoma:
- Viruses: lack cell wall, cell membrane; therefore not affected by antibiotics
- Respiratory infections: for prevention; may block membrane proteins, interfere with release of new virons [amantadine, rimantadine]
- Herpes, Cytomegalovirus infections: for acute phase; terminates DNA-chain synthesis [acyclovir, famciclovir]
- HIV: terminates DNA-chain synthesis [abacavir, zidovudine]
- Hepatits, Leukemia, Kaposi’s Sarcoma: may iinhibit viral RNA translation [interferon]
Anti-viral
HIV Drugs
- Nucleoside Reverse Transcriptase Inhibitors (NRTIs):
- Nucleotide Reverse Transcriptase Inhibitors(NtRTIs):
- Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs):
- Protease Inhibitors (Pls):
- Fusion Inhibitors:
-NRTIs: inhibit reverse transcriptase➡ DNA chain termination [didanosine, lamivudine, zalcitibine, zidovudine, emtricitabine, abacavir]
- NtRTIs: inhibit reverse transcriptase ➡ DNA chain terminatio [tenofovir]
- NNRTIs: bind reverse transcriptase, inhibiting RNA and DNA-directed DNA plymerase functions [delavirine, efavirenz, nevirapine]
- PIs: bind protease ➡ inhibits virus particles [amprenavir, atazamavor, lopinavir, ritonavir, saquinavir, indinivir]
- Fusion: denies cell entry [pentafuside]
7 steps of HIV Replication
- HIV virus binds cell receptor
- Virus penetrates cell, HIV RNA enters cell
- Reverse transcription: single strand viral RNA ➡ double strand DNA by reverse transcriptase enzyme
- Viral DNA combined with cell’s DNA by integrase enzyme
- Transcription: viral proteins assembled
- immature virus emerges from cell
- Maturation of functional virus
Where HIV Drugs Work
- HIV virus binds cell receptor
- Virus penetrates cell, HIV RNA enters cell
- Reverse transcription: single strand viral RNA ➡ double strand DNA by reverse transcriptase enzyme
- Nucleoside Reverse Transcriptase inhibitors
- Nucleotide Reverse Transcriptase Inhibitors
- Non-Nucleoside Reverse Transcriptase Inhibitors
4. Viral DNA combined with cell’s DNA by integrase enzyme
5. Transcription: viral proteins assembled
x-Protease Inhibitors
- Immature virus emerges from cell
7 Maturation of functional virus
