Mel's Pharmacology Lecture Nov 06
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- Name 6 Abuses of Antibiotics
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1. for viral infections
2. fever of unknown origin (vaild in immune compromised patients)
3. too small or too large of a dose
4. administration before culture and sensitivity analysis
5. used instead of proper cleansing
6. not finishing prescribed amount / sharing medications - Describe selective toxicity and 3 ways it is attained in antimicrobial therapy
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Selective toxicity is the ability of a drug to injure invading microbes without injuring cells of the host.
Antibiotic therapies achieve this by:
1) targeting bacterial cell wall
2) inhibiting enzyme unique to the bacteria
3) disrupting the protein synthesis of bacterial cells - Describe narrow spectrum antibiotics versus broad spectrum antibiotics
- Narrow spectrum antibiotics are active against only a few microorganisms, whereas broad-spectrum antibiotics are active against a wide array of microbes
- How can we (in the hospital) delay resistance and the emergence of antibiotic resistance (in 4 basic ways)
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1. Prevent infection (e.g. decrease invasive procedures, tubes, lines)
2. diagnosing and treating infection effectively (target microorganism / infection)
3. Using antimicrobial drugs wisely (vancomycin "big guns" as last resort, stop drugs when infection is gone)
4. prevent patient-patient transmission--break the chain of resistant infections - What is the difference between bacteriostatic drugs and bactericidal drugs
- Bacteriostatic drugs suppress growth, bactericidal drugs kill bacteria
- Resistance: What is it? How are resistant bacteria spreading? Are antibiotics causing the creation of resistant bacteria?
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* Antibiotic resistant bacteria respond slower or not at all to antibiotic therapies.
* They acquire resistant properties through "conjugation", where the bacteria's DNA coding for drug resistance is passed from one bacteria to another
* Antibiotics do not cause the genetic changes, but promote the emergence of drug-resistant organisms by creating selection pressures that favor them. - Name 4 appropriate prophylactic antimicrobial treatments
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1. certain surgeries
2. neutropenia
3. recurrent uti's
4. patients at risk for bacterial endocarditis -
What is cross resistance?
Broad spectrum vs. narrow spectrum -
* Cross resistance is when bacteria become resistant to ANOTHER antibiotic with the same compounds.
* More risk of resistance with use of broad spectrum antibiotics versus narrow spectrum bacteria - What is the MIC of an antibiotic?
- The MIC (minimum inhibitory concentration) of an antibiotic is the lowest concentration of drug needed to completely suppress bacterial growth
- Describe 5 General Adverse Reactions to Antibiotics
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1) Allergy/Hypersensitivity
2) GI upset (take w meals/ may have decreased absorption)
3) Suprainfection: while you're taking care of one infection (killing bacteria in your body, including good bacteria) a second one emerges (i.e., yeast infections)
4) Organ toxicity--liver (fatty infiltrate, jaundice) usually on higher doses - 4 Types of Penicillins (we are on the 3rd - 4th generation)
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1. Penicillin V: similar to G, narrow spectrum, more stable in stomach acid, preferred for oral
2. Penicillin G: 1st penicillin, narrow spectrum
3. Ampicillin: broad spectrum, IV or oral
4. Amoxicillin: broad spectrum, oral, very similar to Ampicillin, but more acid resistant--better choice for oral -
Penicillin
*Mechanism of Action
*Uses
*Forms
*Elimination -
*ACTION: Penicillins weaken the bacterial cell wall, causing lysis and death
*USES: Strep, Syphilis, Meningitis, Anthrax
*Forms: po (empty stomach), IV, IM
*Elimination: Kidneys - Describe 2 types of bacterial resistance to penicillins
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* gram negative bacteria are resistant to penicillins that cannot penetrate the gram negative cell envelope
* some bacteria resist penicillins by producing enzymes that inactivate penicillins -
Cephalosporins:
* Mechanism of Action
* Uses
* Forms
* Elimination -
* Cephalosporins are beta-lactam antibiotics that weaken the bacterial cell wall--they are similar in structure and action to penicillin
* UTI, mastitis
*FORMS: po, IV, IM
* Elimination: Kidneys - CEPHALOSPORINS: 1ST - 4TH GENERATIONAL DIFFERENCES
- As you progress from 1st generation - 4th generation agents, there is 1) increasing activity against gram - bacteria, 2) increasing resistance to destruction by beta-lactamases, 3) increasing ability to reach the cerebral spinal fluid
- CEPHALOSPORINS: Allergic reactions/sensitivities
- DO NOT GIVE CEPHALOSPORINS TO PATIENTS THAT HAVE A SEVERE PENICILLIN REACTION
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Cephalexin (Keflex)
* Classification
* Uses
* Form
* Allergic Warnings -
* Cephalosporin (broad spectrum)
* UTI, RTI, Septicemia, Otis Media, Mastitis
* p.o. Give with food/milk
* Don't give if severe penicillin -
TETRACYCLINE:
*description
*mechanism of action -
*Broad spectrum
*Inhibits bacterial protein synthesis
*Bacteriostatic (suppress growth and replication)--second line agents used primarily for infections resistant to first line agents -
TETRACYCLINE:
*uses
*forms
*elimination
*3 side effects
*nursing implications -
*Uses: chlamydia, lyme, anthrax
*Forms: po, iv, im, topical
*Elimination: kidneys, liver
*Side effects: photosensitivity, discolored teeth, GI upset
*nursing implications: no milk, iron, antacids (absorption will be effected), monitor kidney/liver labs for toxicity -
AMINOGLYCOCIDES (i.e. gentamicin)
*description
*mechanism of action -
AMINOGLYCOCIDES:
*Narrow spectrum, used primarily against aerobic gram - bacilli
*Disrupts protein synthesis resulting in rapid bacterial death (bactericidal) -
AMINOGLYCOCIDES
*uses
*forms
*elimination
*side effects -
AMINOGLYCOCIDES
uses: mrsa
forms: im, iv
elimination: kidneys (can be nephrotoxic)
*ototoxicity
*thrombophlebitis (very toxic medication--watch iv site very carefully)--some hospitals you can only run through a central line