Principles of Chemotherapy II Flashcards
What is the purpose of combination therapy in chemotherapy?
To achieve drug synergy, improve therapeutic effect, reduce resistance, and potentially reduce adverse effects.
Define synergism in the context of antimicrobial agents.
When the inhibitory or killing effects of two or more antimicrobials used together are significantly greater than expected from their individual effects.
Give an example of synergism in antimicrobial therapy for enterococcal endocarditis.
Penicillin + aminoglycoside.
What are examples of improved therapeutic effects through combination therapy?
- M. tuberculosis: INH + rifampin
- P. aeruginosa: gentamicin + carbenicillin.
What is antagonism in combination therapy?
When a drug hinders the effect of another drug.
True or False: Antibacterial prophylaxis is appropriate only when the risk of infection is high.
True.
List some conditions where antibacterial prophylaxis may be used.
- Surgical procedures
- Genital herpes simplex
- Group B streptococcal infections.
What does empirical antimicrobial therapy refer to?
The use of antimicrobial agents before the responsible pathogen is known, based upon experience.
What factors influence the choice of antimicrobial agent in therapy?
- Host factors
- Immunocompromised status
- Liver damage
- Kidney damage
- Age
- Dosing requirements
- Costs.
What is the uniqueness of chemotherapy concerning selective toxicity?
Chemotherapy needs greater toxicity to the parasite than to the host.
Name some mechanisms of drug resistance in pathogens.
- Fails to absorb drug
- Inactivates drug
- Pumps drug out (MDR, P-glycoprotein)
- Modifies drug target.
What are the three methods of horizontal gene transfer in bacteria?
- Transduction
- Transformation
- Conjugation.
True or False: Methicillin-resistant strains of S. aureus (MRSA) are widely distributed among hospitals.
True.
What issue does the emergence of drug-resistant strains pose to healthcare?
It threatens to end the antibiotic era.
What is a superinfection?
Clinical evidence of a new infection during the chemotherapy of a primary one.
Name a common example of a superinfection.
Intestinal candidiasis.
What treatment is often used for fungal superinfections like intestinal candidiasis?
Oral nystatin or amphotericin B.
What is the recommended therapy for pseudomembranous colitis caused by Clostridium difficile?
Discontinue therapy and treat with oral metronidazole or vancomycin.
Fill in the blank: Improper dosage of antibiotics can lead to _______.
Development of resistant strains.
What are some causes of therapy failure in antibacterial treatments?
- Improper dosage
- Improper duration of therapy
- Superinfections.
