Respiratory Infections Quiz Flashcards
Your patient today is a 55 year old male having a 3 day history of worsening SOB, subjective fevers, chills, right sided chest pain and productive cough. Symptoms began about one week ago, he was examined at an ambulatory care clinic and told he had an infection in his lung and received an rx for levofloxacin 750 mg daily. As he was recently “downsized” from his employment as a shipping clerk he is without prescription insurance and could not afford the $250 cost for generic levofloxacin.
His BP, pulse, temp and RR are all elevated. Physical exam of his lungs, CBC with diff, blood gas report, and chest x-ray support probably multilobar CAP involving the RML and RLL.
Gram stain of his sputum reports many gram + cocci in pairs.
The most likely organism is:
A) Staph aureus
B) Strep pyogenes
C) Strep pneumoniae
D) Moraxella cattarhalis
C
Your patient above is hospitalized, placed on oxygen and which antibiotic(s)?
A) Meropenem
B) Ceftriaxone IV + azithromycin IV
C) Piperacillin Tazo-Bactam IV
B
Your patient begins to improve on day 2. The S pneumonia urinary antigen you ordered on admission is positive. Later the sputum culture is reported positive for S pneumoniae, resistant to erythromycin, and sensitive to ceftriaxone, penicillin, levofloxacin, and vancomycin.
On day 4 your patient’s clinical symptoms have almost completely resolved and you are to discharge him home on oral antibiotics to complete a 7 day course of treatment. You prescribe:
A) Levofloxacin oral 750 mg per day
B) Amoxicillin-clavulanate oral 2 G BID
C) Vancomycin 500 mg oral once a day
B
A 24 y/o woman comes to your clinic with complaints of dry cough, headache, fever, and malaise, which have lasted 3 or 4 d. She appears to have 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 the 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 CAP. Which of the following drugs is most suitable?
A) Clindamycin
B) Ampicillin
C) Doxycycline
D) Vancomycin
C - it is often difficult to establish a definite cause of CAP. More than 80% of cases are caused by typical pathogens such as S pneumo, H flu, or M cat and 15% are due to the nonzoonotic atypical pathogens such as Legionella, Mycoplasma or C pneumoniae. Mono-therapy coverage of both typical and atypical pathogens in CAP is preferred to double-drug therapy. Preferred initial therapy includes a macrolide, doxycycline, or a quinolone active against respiratory pathogens. Ampicillin, clindamycin, and vancomycin have low activity against atypical pathogens in CAP.
If the patient was treated with erythromycin she should:
A) Avoid exposure to sunlight
B) Reduce use of caffeinated beverages
C) Avoid taking supplementary iron tablets
D) Stop taking loratadine
B - inhibition of liver cytochrome P450 by erythromycin can lead to serious drug interactions. Although erythromycin does not inhibit loratadine metabolism, it does inhibit the CYP1A2 form of cytochrome P450, which metabolizes methylxanthines like caffeine. 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. Because erythromycin undergoes biliary excretion, there is little reason to assess renal function before treatment.
A 5 day course of treatment for CAP would be effective in this patient with little risk of drug interactions if the drug prescribed were…
Azithromycin - it has a half life of more than 70 hours, which allows for once daily dosing and a 5 day treatment for CAP. Unlike other macrolides, azithromycin does NOT inhibit cytochrome P450 enzymes involved in drug metabolism.
Which drug increases the hepatic metabolism of other drugs?
A) Clarithromycin
B) Erythromycin
C) Ketoconazole
D) Rifampin
D - clarithromycin, erythromycin, and ketoconazole inhibit the hepatic metabolism of various drugs. Rifampin, an inducer of liver microsomal drug-metabolizing enzymes, can increase the metabolism of other drugs.
A 27 y/o pregnant patient with a history of pyelonephritis has developed a severe URI that appears to be due to a bacterial pathogen. The woman is hospitalized and an antibacterial agent is to be selected for treatment.
Which antibacterial agent has efficacy for the treatment of severe URI and appears to be the safest drug to use during pregnancy?
A) Amikacin
B) Azithromycin
C) Ciprofloxacin
D) Tetracycline
E) Erythromycin
B - several groups of antimicrobials are best avoided in pregnancy if at all possible, including aminoglycosides, sulfonamides, and tetracyclines.
The macrolide azithromycin appears to be safe, but studies in animals have shown that clarithromycin, a related macrolide, is potentially embryotoxic.
A 27 y/o pregnant patient with a history of pyelonephritis has developed a severe URI that appears to be due to a bacterial pathogen. The woman is hospitalized and an antibacterial agent is to be selected for treatment.
Assume that all the drugs listed below are active for your patient. Suppose you are concerned about the effects of renal impairment on drug dosage in this patient, which drug would not require dosage modification in renal dysfunction?
A) Amoxicillin
B) Clindamycin
C) Ciprofloxacin
D) Trimethoprim-sulfamethoxazole
B - antimicrobial drugs that are eliminated via hepatic metabolism or biliary excretion include erythromycin, cefoperazone, clindamycin, doxycycline, isoniazid, ketoconazole, and nafcillin.
Amoxicillin, ciprofloxacin and trimethoprim-sulfamethoxazole are eliminated by the kidney.
