Test 4 Microbiology - Chemotherapy

zayiwole's version from 2015-05-03 01:55

Section 1

Question Answer
What do we call antibiotics that kill gram negative and gram positive bacteria?Broad spectrum antibiotics
What do we call it when we give the patient 2 or 3 different antibiotics at once?Combination therapy
Why would we use combination therapy?Activity of one drug enhances the activity of the other. Microbe could be resistant to just one drug
If a drug has a low chemotherapeutic index what does that mean? Is that good or bad?Bad, because it causes harm to the tissue
Name the methods by which antibiotics work?1. Inhibition of cell wall synthesis 2. Disruption of cell membrane 3. Disruption of translation at ribosomes 4. Interference with metabolism 5. Inhibition of nucleic acid synthesis
Penicillin is made by?Fungi (mold)
Who discovered it?Alexander Fleming
How does it harm bacteria?Inhibits synthesis of peptidoglycan cell wall ; Inhibit NAG and NAM crosslinking
What are some problems with penicillins:Overuse has led to resistance Narrow spectrum (gram+) Anaphylactic reaction –many people allergic
What types of microorganisms are affected by penicillin?Staph, strep, syphilis; Primarily gram +
What do we mean by semisynthetic penicillins? Are they only good for gram positive microorganisms?Antibiotic is chemically altered after purification to impart new characteristics Gram+ and -
Why do they add clavulinic acid to penicillin?Inactivates the Penicillinase made by bacteria
What is beta-lactamase?Enzyme that inactivates penicillin
Cephalosporins are described as first generation, second generation, and third generation. What is the difference?1st generation-gram+; 2nd generation-also kill enteric; 3rd generation-pseudomonas
How do these work?Inhibits cell wall synthesis, but is highly resistant to beta-lactamase
Why are these drugs (Cephalosporins) better for some people than penicillin?Do not cause as many allergic reactions

Section 2

Question Answer
Name four other drugs that inhibit the synthesis of the cell wall?1. Carbapenems- broad spectrum Modified beta lactam structure Used for nosocomial diseases 2. Bacatracin – gram + Topical medication 3. Vancomycin Last line of defense for Staph aureus Parenteral route 4. Isoniazid, Ethambutol TB, Inhibit mycolic acid synthesis (combination)
Which drug is used to treat MRSA?Vancomycin
Which of these drugs is for topical application?Bacitracin
Name a drug that inhibits the cell wall synthesis in Mycobacteria?Isoniazid, Ethambutol
Why wouln’t that also affect ( that disrupt ribosomes) human ribosomes?Eukaryotic ribosomes are 80S (60S+40S)
Why can we give drugs that disrupt ribosomes? Prokaryotic ribosomes are 70S (50S+30S)
Aminoglycosides are effective against?Gram negative bacteria
What are some side effects of aminoglycosides?Hearing loss and Kidney damage
Tetracycline is has what kind of spectrum?Broad spectrum
Tetracycline is effective against intracellular bacteria such as:Chlamydia, rickettsia
Tetracycline is effective against bacteria without a cell wall such as:Mycoplasma
What is the problem with tetracycline and children?Discolors teeth, affects bones
What is special about Chloramphenicol?Cross blood brain barrier-Used to treat meningitis Rickettsia, Chlamydia
What about the problem associated with Chloramphenicol? How serious is that?Toxic in children aplastic anemia RBC and WBC count goes down
Which patients get Erythromycin?When patient is allergic to penicillin or organism is resistant
Name the 2 diseases that are often treated with Erythromycin?Legionnaires disease and Atypical pneumonia
Clindamycin is a broad spectrum antibiotic. Such antibiotics have been associated with pseudomembranous colitis? What is that?"Antibiotic-associated diarrhoea" is an infection of the colon. It is often, but not always, caused by the bacterium Clostridium. Diarrhea, cramps, colon ulcerations and bleeding
Name a drug given to combact VRSA?1. Oxazolidinones (linezolid)- Inhibits 50S 2. Streptogramins-combination that bind to 50S of gram positives
How do Rifamphin and Quinolones work?Rifampin-block RNA transcription AND Quinolones-inhibit DNA replication
When is Rifampicin given?Tuberculosis and Meningitis carriers
What is one of the disturbing side effects?Resistance occurs quickly. Red Man Syndrome Orange-red urine

Section 3

Question Answer
What is the side effect of quinolones?Not for pregnant womencartilage development of newborns affected
How do sulfa drugs work?Competitive inhibition of folic acid synthesis
What is the advantage of giving sulfa drugs with trimethroprim?Block 2 steps of folic acid synthesis
When are sulfa drugs prescribed?Urinary tract infections. Pneumocystis pneumonia
Name an antifungal agent given for systemic fungal infections?Amphoterian Bdegrade cell membrane by binding to ergosterol
Name an antifungal agent given topically for skin fungus?Imidazoles-block synthesis of ergosterol
How does acyclovir work?Inhibits replication of DNA Guanosine base analogcauses incorporation of wrong base
Why is it so difficult to come up with antiviral agents?Lack organelles; No cell wall
Why would interferon seem like a good drug to give for viral infections?Blocks the formation fo viral proteins at ribosome
How does AZT work?Reverse transcriptase inhibitor
Some antiviral drugs are neuraminidase inhibitors. Which virus did we discuss that has neuraminidase as one of its spikes?Influenza virus
What would a patient with Trichomonas vaginalis likely be treated with?Metronidazole-damage DNAincorrect replication
Name an antimalaria drug?Chloroquine- accumulates in RBC which affects Plasmodium
Explain how the disk-diffusion method can be used to test bacteria against antibiotics?The zone of inhibition allows you to see the effect the antibiotic has on the microbe