Intro to Antibiotics Quiz Flashcards
Empiric antibiotic guidelines should:
A) Always be followed
B) Be followed unless your patient is already receiving antibiotics in which case you should always continue the same antibiotics
C) Be used in conjunction with the patient’s medication history
D) Always start your patients on a quinolone
C
When dosing aminoglycosides and vancomycin it is important to:
A) Every patient should receive the same dose
B) Select the dose proportional to the patient’s weight, and the dose interval inversely proportional to the patient’s renal function
C) Select the dose inversely proportional to the patient’s weight, and the dose interval proportional to the patient’s renal function
D) Use a quinolone instead you won’t have to do all these calculations
B
Match the antibiotic class with its MOA:
- Cephalosporins
- Aminoglycosides
- Erythromycins
- Sulfonamides
- Quinolones
A. Inhibit protein synthesis
B. Inhibit DNA/RNA replication or transcription
C. Generate defective proteins
D. Block cell wall synthesis
E. Inhibit folic acid metabolism
- D
- C
- A
- E
- B
Oxacillin is stable to beta-lactamase enzymes; in ampicillin/sulbactam- ampicillin is fortified with sulbactama beta-lactamase inhibitor. So what is the mechanism of MRSA- resistance?
A) High octane beta-lactamase is generated
B) Bacteria are never resistant to antibiotics that contain a beta-lactamse inhibitor
C) Alterations to penicillin binding proteins decrease the affinity for binding to the antibiotic agents
D) Bacteria learn to live without a cell wall
C
Which of the following antimicrobials is effective at treating both anaerobic infections, and gram positive infections within the respiratory tract?
A) Ciprofloxacin
B) Clindamycin
C) Erythromycin
D) Metronidazole
B
Which of the following penicillins is most likely to be active against MSSA? (methcillin senstive S. aureus)
A) Amoxicillin
B) Ampicillin
C) Dicloxacillin
E) Azithromycin Z-pack
C - active against MSSA, but 60% of isolates are MRSA
A highly effective example (antibiotics have different mechanisms of action) of double gram negative antibacterial coverage is:
A) Aztreonam plus piperacillin
B) Vancomycin plus linezolid
C) Metronidazole plus sulfamethoxazole
D) Ceftazidine plus tobramycin
D
Which of the following organisms is a gram-negative anaerobe?
A) Bacteroides
B) E coli
C) Enterococcus
D) Streptococcus
A
Write a prescription for Kelly Frears a 40 y/o F confirmed to have streptococcal pharyngitis. She has no other medical problems, is not taking any other medications. She broke out in itchy hives, and had difficulty breathing the only time she has received a penicillin in the past. She is not allergic to any other medications. Choose the antibiotic appropriate for Ms Frears, having the narrowest spectrum that is active against the most likely organism-GAS. Include the medication, dose, route of administration, frequency and duration of treatment.
Ms. Frears’ diagnosis of GAS means she needs a narrow spectrum antibiotic that has gram positive coverage due to the likelihood of strep pyogenes causing her illness. Because she showed a true allergic response to penicillin (type 1 hypersensitivity reaction), cephalosporins are ruled out and azithromycin is the best option.
Her prescription would be:
Azithromycin 12mg/kg
Take one pill by mouth once a day for 5 days.
Fotis blurb:
Likely Ms.Frears has a type 1 reaction to penicillin ruling out penicillin, and cephalosporin options.
Azithromycin 500 mg PO once daily for 5 days is recommended by the American Heart Association (AHA) and the Infectious Diseases Society of America (IDSA) as an alternative in patients allergic to penicillin. I am less comfortable with the older FDA-approved dosage of 500 mg PO on day 1, followed by 250 mg PO once daily for 4 days.
A 32-year-old woman recently treated for leukemia is admitted to the hospital with malaise, chills, and high fever. Gram stain of blood reveals the presence of gram-negative bacilli. The initial diagnosis is bacteremia, and parenteral antibiotics are indicated. The records of the patient reveal that she had a severe urticarial rash, hypotension, and respiratory difficulty after oral penicillin V about 6 mo ago. The most appropriate drug regimen for empiric treatment is
A) Meropenem
B) Ceftriaxone
C) Aztreonam
D) Oxacillin
C - each of the drugs listed has activity against some gram-negative bacilli. All penicillins should be avoided in patients with a history of allergic reactions to any individual penicillin drug. Cephalosporins should also be avoided in patients who had anaphylaxis or other severe HSR reactions after penicillin use. There is a partial cross-reactivity between penicillins and the carbapenems such as imipenem and meropenem, but no cross-reactivity between penicillins and aztreonam.
Your patient is 12 years old is diagnosed with otitis media which in this case needs to be treated with antibiotics. You choose amoxicillin. The primary mechanism of action of amoxicillin involves the inhibition of……?
A) Alpha and Beta Lactamases
B) Cell membrane synthesis
C) Peptidoglycan cross linking
D) Transglycosylation
C - penicillins bind to PCBs and inhibit peptidoglycan cross linkage, Vancomycin inhibits transglycolase
Which statement about vancomycin is accurate?
A) Bacteriostatic
B) Active against MRSA
C) Binds to PBPs
D) Can be used orally for all indications
B - vanco is bacteriCIDAL, inhibits cell wall synthesis but does not bind PBPs, and thus is not susceptible to beta lactamases. it is not absorbed after oral administration – only given the oral route to manage GI infection.
considered the drug of choice against MRSA
Clarithromycin and erythromycin have very similar spectra of antimicrobial activity. The major advantage of clarithromycin is that it:
A) Does not inhibit hepatic drug metabolizing enzymes
B) Eradicates mycoplasmal infections in a single dose
C) Has greater activity against H pylori
D) Is active against strains of streptococci that are resistant to erythromycin
C - Clarithromycin can be administered less frequently than erythromycin, but it is not effective in single doses against susceptible organisms. Organisms resistant to erythromycin, including pneumococci and methicillin-resistant staphylococci, are also resistant to other macrolides. Drug interactions have occurred with clarithromycin through its ability to inhibit cytochrome P450. Clarithromycin is more active than erythromycin against M avium complex, T gondii, and H pylori.
A 24-year-old woman comes to clinic with complaints of dry cough, headache, fever, and malaise, which have lasted 3 or 4 d. She has some respiratory difficulty, and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of expectorated sputum fails to reveal any bacterial pathogens. The patient mentions that a colleague at work had similar symptoms to those she is experiencing. The patient has no history of serious medical problems. She takes loratadine for allergies and supplementary iron tablets, and she drinks at least 6 cups of caffeinated coffee per day. You make an initial diagnosis of community-acquired pneumonia.
If you decide to treat with erythromycin, your patient should
A) Avoid exposure to sunlight
B) Avoid taking supplementary iron tablets
C) Decrease her intake of caffeinated beverages
D) Temporarily stop taking loratadine
C - The inhibition of liver cytochrome P450 by erythromycin has led to serious drug interactions. Although erythromycin does not inhibit loratadine metabolism, it does inhibit the CYP1A2 form of cytochrome P450, which metabolizes methylxanthines. Consequently, cardiac and/or CNS toxicity may occur with excessive ingestion of caffeine.
Unlike the tetracyclines, the oral absorption of erythromycin is not affected by cations and the drug does not cause photosensitivity.
A 5-d course of treatment for community-acquired pneumonia would be effective in this patient with little risk of drug interactions if the drug prescribed were
A) clindamycin
B) vancomycin
C) azithromycin
C - Azithromycin has a half-life of more than 70 h, which allows for once-daily dosing and a 5-d course of treatment for community-acquired pneumonia. Unlike other macrolides, azithromycin does not inhibit cytochrome P450 enzymes involved in drug metabolism.
