Exam 2: Intro To Chemotherapy Flashcards
What are the 4 characteristics of chemotherapy
1) selective toxicity to parasite than host, although not always possible
2) hypersensitivity and organ directed toxicity is a potential problem
3) Chemo selects for resistant strains (IMPORTANT)
4) Chemo lowers the microorganism load so the host can better fight it off
What antibiotics have hepatotoxicity?
Tetracyclines, isoniazid, erythromycin estolate, Clindamycin, sulfonamides, and amphotericin B
What antibiotics have renal toxicity?
Cephalosporins, vancomycin, aminoglycosides, sulfonamides, and amphotericin B
What antibiotics have ototoxicity?
Aminoglycosides, vancomycin, and minocycline (Vestibular only)
What antibiotics have hemopoietic toxicity?
Many antiviral agents, chloramphenicol, and sulfonamides
What antibiotics have visual toxicity?
Ethambutol and isoniazid
What is multiple drug resistance often transmitted by?
Plasmids
What are the two ways that antimicrobial resistance may be acquired?
It can be passed vertically or hortizontal transfer
Describe vertical transmission in regards to antimicrobial resistance.
The trait is passed onto daughter cells. After 2 generations, 100% of that population has the trait
What are the 3 ways that horizontal transfer can occur?
Transduction, transformation, and conjugation
What is transduction?
When a bacteriophage injects viral DNA into a bacteria. Bacteria can then replicate it and pass it on
What is transformation?
When a bacterial cell lyses and DNA is freed. DNA is then picked up by a different bacteria and inserted into its own sequence.
What is conjugation?
When two bacteria cells connect via a pilus and exchange information. Can be interspecies and required direct contact
Why does Antibiotic resistance happen so quickly?
High rate of genetic replication in bacteria
What is empirical therapy?
When antibiotics are given before the responsible pathogen is normal. Typically broad spectrum antibiotics
Is the inhibitory concentration for bacteriostatic drugs higher or lower than bactericidal?
Much lower
What is important to remember about bacteriostatic drugs and immunocompromised patients?
The bacteriostatic drugs do not kill the bacteria, but stop it from growing. Immunocompromised patients cannot kill off the bacteria themselves, so when taken off the antibiotic, the infection will continue to grow.
What is concentration dependent killing?
When the rate and extent of bacterial killing is dependent on drug concentration.
The higher the drug concentration, the faster the bacteria are killed.
What is time dependent killing?
When the bacterial killing is not increased with increasing concentrations, but dependent on the time of exposure to the drug.
Are cell wall inhibitors bactericidal or bacteriostatic?
Bactericidal
Are most protein synthesis inhibitors bactericidal or bacteriostatic?
Bacteriostatic
What is a postantibiotic effect (PAE?
Persistent suppression of bacterial growth after limited exposure to an antimicrobial agent
What is the benefit of having a drug with a high PAE?
You can dose farther apart. This can increase patient compliance decrease side effects.
What is synergism?
When the inhibitory or killing effects of two or more antimicrobial used together are significantly greater than expected from their effects when used individually
What are the 3 synergistic mechanisms?
1) blockade of sequential steps in metabolic sequence
2) inhibition of enzymatic inactivation (beta lactamase inhibitors)
3) Enhancement of antimicrobial agent uptake
What are the two major mechanisms of antagonism?
1) Inhibition of bactericidal activity by bacteriostatic agents
2) Induction of enzymatic inactivation (some gram negative bacteria contain inductively beta lactamases)
What are the main misuses of antibiotics and causes of failure of therapy?
Treating untreatable infections (Varicella), treating a fever of undetermined origin, improper dosage, and improper duration of therapy
What are superinfections most frequently observed with?
Broad spectrum antibiotics
What is intestinal candidiasis and how is it treated?
It is the most common (fungal) superinfection. Usually antibiotic therapy is continued and the fungal superinfection is treated with oral nystatin or amphotericin B
How is staphylococcal enterocolitis treated?
This is a life threatening superinfection.
Discontinue the antibiotic therapy and treat the staphylococcus with oral vancomycin
What is pseudomembranous colitis and what is it treated with?
This life threatening superinfection first seen after Clindamycin. Caused by C. Diff.
Discontinue therapy and treat with oral metronidazole or vancomycin.
When should antibacterial prophylaxis be used?
In circumstances in which efficacy has been demonstrated and benefits outweigh the risk of prophylaxis
What antibiotic is given as prophylactic treatment prior to surgery?
Cefazolin
What is the prophylactic treatment for group B streptococcal infections?
Ampicillin or penicillin G
What is the prophylactic treatment for Meningococcal infections and haemophilus influenzae type B infections?
Rifampin
What is the prophylactic treatment for Malaria?
Chloroquine
What is the prophylactic treatment for pertussis?
Erythromycin
What is the prophylactic treatment for pneumococcemia?
Penicillin G
What is the prophylactic treatment for TB?
Isoniazid
What is the prophylactic treatment for UTI?
Trimethoprim-sulfamethoxazole
