Antimicrobials Flashcards
Spectrum of microbial coverage of aminoglycosides ____ spectrum of coverage of third generation of cephalosporins.
a. Cannot be compared to
b. Is equal to
c. Is less than
d. Is greater than
c. Is less than
Duration of action of decadron ____ duration of action of prednisone.
a. Is not able to be compared to
b. is less than
c. Is equal to
d. Is greater than
D. Is greater than
Adverse drug effects of anti-retrovirals used to manage HIV ____ adverse drug effects of macrolides used to manage pneumonia.
a. Greater than
b. Less than
c. Equal to
a. Greater than
A 32 yo female who is 9 weeks pregnant presents with nasal congestion B/L. She has been using an OTC intranasal decongestant for 3 weeks, but her symptoms have not improved. Physical exam shows a midline septum and 4+ turbinates. The nasal mucosa is hyperemic and erythematous without cobblestoning. She denies illicit drug use. Which medication is most appropriate to help ease her symptoms as she weans off the topical decongestant?
a. Oral prednisone, a corticosteroid
b. Intranasal fluticasone, a corticosteroid
c. Oral ibuprofen, an anti-inflammatory
d. Intranasal azelastine, an anti-histamine
b. Intranasal fluticasone, a corticosteroid
Rhinitis medicamentosa (RM), also known as “rebound congestion,” is inflammation of the nasal mucosa caused by the overuse of topical nasal decongestants. It is considered a subset of drug-induced rhinitis. Tolerance rather than tachyphylaxis, as tachyphylaxis occurs in 1-2 doseas. Tolerance to these nasal sprays takes about 7 days of use.
RM treatment involves d/c of the topical decongestant. The use of intranasal corticosteroids has been reported to minimize the symptoms of rebound congestion. They have an anti-inflammatory effect, which helps to reduce mucosal swelling and erythema.
Intranasal steroids help relieve the symptoms, but systemic corticosteroids are also prescribed in a few cases. Systemic corticosteroids are effective but should be avoided in the first trimester of pregnancy because of the risk of producing gastroschisis.
Spectrum of microbial coveage of aminoglycosides ____spectrum of coverage of third generation of cephalosporins.
a. Greater than
b. Less than
c. Equal to
d. Cannot be compared to
b. Less than
Duration of action of decadron is ____ duration of action of prednisone.
a. Greater than
b. Less tahn
c. Equal to
d. Not able to be compared to
a. Greater than
A 24 yo pt who is in the third trimester of pregnancy presents with urinary frequency, urgency, and fever. She is dx’d with a UTI. Which of the following abx is most appropriate to treat the infection in this pt?
a. Trimethoprim/sulfamethoxazole
b. Doxycycline
c. Amoxacillin
d. Gentamicin
c. Amoxacillin
Trimethoprim/sulfamethoxazole is avoided in pregnancy due to the risk of kernicterus during the third trimester.
Doxycycline is voaided in pregnancy due tot he risk of enamel hypoplasia.
Aminoglycosides, such as gentamicin and amikacin are also avoided due to their teratogenic risks.
Beta-lactams, such as amoxicillin, are generally considered safe for use in pregnancy.
A 56 yo F presents with fever, cough, and SOB upon adm. Her CXR shows B/L infiltrates consistent with pna. Respiratory cultures are pending, and she is initiated on a combination of ceftriaxone and azithromycin. Which of the following best describes the use of these antibiotics?
a. Concentration-dependent killing therapy
b. Definitive therapy
c. Empiric therapy
d. Prophylactic therapy
c. Empiric therapy
Empiric therapy is initiated before a causative microorganism is identified. Empiric therapy is designed to cover the most common causitive organisms at the site of infection.
The combination of ceftriaxone and azithromycin is often used in the empiric tx of pna, and together the 2 agents provide coverage of some of the most likley organisms such as Streptococcus pneumoniae, Haemophilus influenzae, and Mycoplasma pneumoniae.
If a microorganism is later identified, the therapy can be adjusted approprirately based on the sensitivities of the organism (definitive therapy).
Both the cephalosporin (ceftriaxone) and the macrolide (azithromycin) provide time-dependent killing.
Prophylactic therapy is used to prevent infection, rather than treat and active infection.
Which of the following antimicrobials should be closely monitored in a pt with kidney dysfunction due to the risk of drug accumulation and toxicity
a. Doxycycline
b. Amikacin
c. Rifampin
d. Tetracycline
b. Amikacin
Amikacin, an aminoglycoside, is primarily eliminated renally. Aminoglycoside therapy should be avoided or used with caution in patietns with kidney dysfunction. Drug concentrations should be monitored closely in patietns with renal dysfuntion. Tetracycline, doxycycline, and rifampine are primarily eliminated via the hepatic route.
A 39 yo pt is scheduled to have a total knee placement. Which of these antimicrobial agents is most appropriate for surgical prophylaxis to cover microorganisms such as Staphylococcus aureus and Streptococcus pyogenes?
a. Levofloxacin
b. Isoniazid
c. Vancoymcin
d. Cefepime
c. Vancoymcin
Levofloxacin and cefepime would not be appropriate choices to provide coverage for sin micobiota due to their broader spectrum of activity.
Isoniazid is a narrow-spectrum agent preferred for TB.
Vancomycin is an agetn of choice, as it provides excellent coverage for skin microbiota such as Staphylococcus spp. and Streptococcus spp.
A pt is infected by a gram-negative organisms that is resistant to barnapenems, likely due to altered porin channels. This is an example of what mechanism of drug resistance?
a. Altered targets
b. Decreased accumulation
c. Lipopolysaccharide modification
d. Enzymatic inactiavation
b. Decreased accumulation
Gram-negative organisms, in particular, can later the number or structure of porins, a type of protein channel in their outer membranes, which decreases drug permeability, and leads to decreased accumulation of the drug.
Which of the following antimicrobials are eliminated via hepatic metabolism or biliary excretion? Check as many as apply.
a. Naficillin, a penicillin
b. Isoniazid, an anti-TB, anti-mycobacterium agent
c. Erythromycin
d. Doxycline
e. Ketoconazole, an antifungal
f. Clindamycin
a. Naficillin, a penicillin
b. Isoniazid, an anti-TB, anti-mycobacterium agent
c. Erythromycin
d. Doxycline
e. Ketoconazole, an antifungal
When evaluating drug therapy for meningitis, which of the following factors is expected to have the last influence on the penetration and concentration of an antibacterial agent in the CSF?
a. Lipid solubility of the drug
b. Minimum inhibitory concentration of the drug
c. Protein bidning of the drug
d. Molecular weight of the drug
b. Minimum inhibitory concentration of the drug
Although the minimum inhibitory concentration impacts the effectiveness of the drug against a bacteria, it does not affect the ability of a drug to cross the BBB. Lipid solubility, protein binding, and molecular weight all determine the likelihood of a drug to penetrate the BBB and concentrate in the CSF.
Which of the following antimicrobials exhibits a long postantibiotic effect that permits once-daily dosing?
a. Gentimicin
b. Penicillin G
c. Vancomycin
d. Aztreonam
a. Gentimicin
Aminoglycosides, including gentimicin, possess a long postantibiotic effect, especially when given as a high dose every 24 hours.
Pencillin G, clincamycin, and vancomycin have a relatively short postantibiotic effect and require dosing that maintains concentrations above the MIC for a longer portion of the dosing interval
Antimicrobials: how do they not affect the host?
- Biochemical differences between humans and microorganisms
- Selective toxicity - ability to kill/harm microorganism and not the host
- Relative rather than absolute; control concentrations to target microorganism and still be tolerated by host
