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CRRAB II Week 8/9 - WLB > Antibiotic Review - A.Prunuske > Flashcards

Antibiotic Review - A.Prunuske Flashcards

1
Q

What factors in presentation suggests pharyngitis is bacterial?

A
  • Fever
  • Exudate
  • No cough
  • Young age (< 20)
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2
Q

What part of Streptococcus does a rapid antigen detection test/throat swab detect?

A

C-carbohydrate

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3
Q

What is the sensitivity and specificity of a rapid antigen detection test for streptococcus?

A

specificity (>95%) but sensitivity is (80%)

  • Why might the sensitivity be low?
    • Will miss 20% of cases (people with disease test negative) → due to variation in C-carbohydrate or you do not get enough organism with swab to get positive results
    • culture might get more sample and will be easier to get positive results
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4
Q

What should you do after you get a negative rapid antigen test for streptococcus?

A

take culture (Gold standard)

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5
Q

Why is treatment important in Streptococcus pharyngitis?

A

Treatment prevents sequelae, alleviates symptoms, and decreases spread.

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6
Q

What is the appropriate antibiotic for treatment of Group A streptococcal pharyngitis?

A
  • Penicillin V (oral) - $15
  • Penicillin G (IM) - $119
  • Amoxicillin (can get liquid form)
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7
Q

What is the MOA of Penicillin?

A

Cell wall inhibitor/Beta-lactam:

inhibit cross-linking by binding to transpeptidases

(Beta-lactams bind to the Penicillin Binding Proteins which are transpeptidases required for cell wall synthesis)

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8
Q

What could happen if you treat Streptococcal pharyngitis with Ampicillin?

A

Ampicillin can cause a rash with Streptococcus pyogenes, which can incorrectly label the individual as having a penicillin allergy.

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9
Q

What class of antibiotics all have shared characteristics of Beta-lactams?

A
  • penicillins
  • cephalosporins
  • carbapenems
  • aztreonam
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10
Q

All beta-lactam drugs are bactericidal/bateriostatic?

(Pick one)

A

Bactericidal → cell lysis

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11
Q

Which antibiotics could you use to treat Streptococcal pharyngitis if the patient was allergic to penicillins?

A
  • Cephalexin (Keflex)
  • Cefadroxil
  • Clindamycin
  • Azithromycin
  • Clarithromycin
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12
Q

Aztreonam is a monobactam that is safe to use in patients with penicillin allergies, but why wouldn’t it be a good choice for Streptococcus pharyngitis?

A

It is only effective against Gm (-) bacteria

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13
Q

What kind of antibiotics are not advisable for immunocompromised or life-threatening acute infections?

A

Bacteriostatic

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14
Q

What is mechanism of action of macrolides?

A

Binds to 50S ribosomal RNA near the peptidyltransferase center blocking peptide chain elongation (inhibiting translocation).

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15
Q

What are the three macrolides that we need to know?

A
  • Azithromycin (unique; does not inhibit CYP3A4)
  • Clarithromycin
  • Erythromycin
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16
Q

What spectrum of pathogens do macrolides treat?

A

Broad coverage of respiratory pathogens

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17
Q

What are the adverse side effects of macrolides?

A
  • GI discomfort
  • Prolonged QT interval
  • Hepatic failure- inhibits CYP3A4
  • Clarithromycin associated with miscarriages
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18
Q

What are five reasons that macrolide treatment of Strep pharyngitis might fail?

A
  1. Antibiotic resistance
    • rare for penicillin in Streptococcus pyogenes but 5-8% of strains are resistant to macrolides (methylation of 23S rRNA binding site or increased efflux)
  2. Lack of compliance
    • patient feels better after a few days and doesn’t finish full course (patients are worried they are becoming resistant not bacteria)
  3. Pharyngitis is caused by virus or other organism
  4. Superinfection with Candida after being on penicillin
  5. Neighboring flora can impact treatment
    • Haemophilus influenzae secrete beta-lactamases
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19
Q

What drugs treat Influenza A & B?

A

Neuraminidase inhibitors

  • prevents viral release, most active 48 hrs after infection, effective for both influenza A and B
  • oseltamivir, zanamivir, peramivir
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20
Q

What influenza A & B treatment can be used in patients > 1 yr, is an oral prodrug activated by hepatic esterases, goes by the brand nameTamiflu, has to be modified for renal insufficiency, is preferred for pregnant, and commonly has GI side effects, headache, fatigue?

A

oseltamivir

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21
Q

What influenza A & B treatment can be used in patients >7 yrs and can be inhaled if malabsorption or GI problems, but should not be used if there are other airway diseases like COPD or asthma?

A

zanamivir

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22
Q

What influenza A & B treatment can be used in patients >18 yrs old, is administered IV with one dose, and is new this year?

A

peramivir

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23
Q

Why are rates of mutation in influenza virus so high?

A
  • Antigenic drift
    • few small genetic changes, but still some cross immunity with previous strains
  • Antigenic shift
    • create a whole new subtype through rearrangement of RNA
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24
Q

What is Pre-emptive antiobity therapy?

A

actively screening for infection, pre-symptomatic treatment for pts with high risk

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25
Q

Urine antigen tests for the diagnosis of what respiratory infections?

A
  • legionellosis
  • histoplasmosis
  • pneumococcal pneumonia
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26
Q

What organisms commonly cause Community-Acquired Pneumonia?

A
  • Streptococcus pneumoniae
  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Chlamydophila pneumoniae
  • Legionella species
  • Mycoplasma pneumoniae
  • Viruses: influenza, RSV, parainfluenza, adenovirus 14, human metapneumovirus, rhinovirus
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27
Q

What empiric antibiotic treatment is appropriate for community-acquired pneumonia in previously healthy outpatients with no antibiotic use in the past 3 months?

A
  • Macrolide
    • Azithromycin
    • Erythromycin
    • Clarithromycin
  • Doxycycline
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28
Q

What empiric antibiotic treatment is appropriate for community-acquired pneumonia in outpatients with comorbidities or antibiotic use in the last three months?

A
  • Respiratory fluoroquinolone
    • Levofloxacin
    • Gemifloxacin
    • Moxifloxacin
  • High dose beta-lactam + Macrolide
    • Amoxicillin
    • Amoxicillin/Clavulanate (Augmentin)
    • Cefpodoxime
    • +
    • Azithromycin
    • Erythromycin
    • Clarithromycin
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29
Q

Why should you be worried about prior antibiotic use within 3 months when treating community-acquired pneumonia?

A

Prior antibiotic use, increases the likelihood of having drug resistant Streptococcus pneumonia usually due to a change in penicillin-binding protein or macrolide resistance.

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30
Q

What are the three respiratory fluoroquinolones that we need to know?

A
  • Gemifloxacin
  • Levofloxacin
  • Moxifloxacin
31
Q

What is the MOA of respiratory fluoroquinolones?

A
  • Bactericidal
  • Direct inhibitor of DNA replication by binding bacterial DNA topoisomerase II (gyrase) and IV
32
Q

What spectrum of pathogens do respiratory fluoroquinolones treat?

A
  • Broad spectrum:
    • Gram (+)
    • Gram (-)
    • atypical organisms like Mycoplasma
33
Q

What forms of bacterial resistance can occur with respiratory fluoroquinolones?

A

Overprescribed!

  • Active efflux of the drug
  • Mutations in topoisomerases
34
Q

What are the adverse side effects of respiratory fluoroquinolones?

A
  • GI discomfort
  • Tendinopathies
  • Avoid in pregnancy, lactating, children
35
Q

A 21 year old female college student presented with a 5-day history of low-grade fever, myalgia, headache, and nonproductive cough. Gram stain had a few inflammatory cells but did not show any significant pathogen. Which of the following is the most likely cause of her illness?

A. Mixed anaerobic infection

B. Chlamydia trachomatis

C. Streptococcus pneumoniae

D. Mycoplasma pneumoniae

E. Histoplasma capsulatum

A

D. Mycoplasma pneumoniae

(especially for this age group)

36
Q

What of the following classes of antibiotics would you predict to be ineffective for Mycoplasma pneumoniae?

  • A. Aminoglycosides
  • B. Cephalosporins
  • C. Fluoroquinolones
  • D. Macrolides
  • E. Tetracyclines
A

B. Cephalosporins → target cell wall (mycoplasma doesn’t have a cell wall)

37
Q

What kind of pneumonia does Mycoplasma pneumonia typically cause?

A

atypical pneumonia → “walking pneumonia”

38
Q

How do you diagnose/treat pneumonia due to Mycoplasma pneumonia?

A
  • Hard to culture so diagnosis involves testing for IgM (serology)
  • Doxycycline, Azithromycin
    • Beta-lactams are not effective, adheres to epithelial cells
  • Difficult to prevent because patients are infectious for extended periods of time even during treatment
39
Q

What is the MOA of Tetracyclines?

A

Tetracycline → Doxycyline

Bacteriostatic-bind 30S preventing attachment of aminoacyl-tRNA (A-site), inhibiting elongation

40
Q

What is the only Tetracycline antibiotic that we need to know?

A

Doxycycline

41
Q

What spectrum of pathogens does Tetracycline treat?

A
  • limited by resistance
  • B. burgdorferi, H. pylori, Mycoplasma pneumoniae
  • not good against Gm (-) rods
42
Q

What form of resistance to Tetracyclines can bacteria develop?

A

Reduced uptake and increased efflux

(Resistance is widespread)

43
Q

What are the adverse side effects of Tetracycline antibiotics?

A
  • Photosensitivity
  • Discoloration of teeth,
  • Inhibits bone growth- avoid pregnancy, children
  • Oral absorption limited by cations
44
Q

What two classes of antibiotics have concentration-dependent killing properties and achieve more killing at a higher concentration?

(Peak concentration >10 times over MIC, 1 or 2 high daily doses)

A
  • Aminoglycosides
    • Streptomycin
    • Gentamicin
    • Tobramycin
  • Fluoroquinolones
    • Ciprofloxacin
    • Levofloxacin
    • Moxifloxacin
45
Q

What two classes of antibiotics have time-dependent killing properties and have t1/2 > Maximum Inhibitory Concentration?

(depending on the half life of the antibiotic may need to dose multiple times/day may not)

A
  • Beta-lactams
    • Penicillins
    • Cephalosporins (Cephalexin, Ceftriaxone, Cefepime)
    • Carbapenems (Imipenem, Meropenem)
  • Vancomycin
46
Q

What is Klebsiella pneumoniae carbapenemase (KPC)?

A
  • Hospital-acquired pneumonia
  • Not spread through the air but on health care providers hands
  • Expresses extended spectrum Beta-lactamase (ESBL)
  • Colistin- polymyxin E- binds phosphatidylethanolamine in Gram-negative membrane to create holes in membrane
    • Very nephrotoxic!
47
Q

What pathogens cause the majority of U.S. hospital infections, and presently “escape” the arsenal of currently available antibiotics?

A
  • E: Enterococcus faecium
  • S: Staphylococcus aureus
  • K: Klebsiella pneumoniae
  • A: Acinetobacter baumannii
  • P: Pseudomonas aeruginosa
  • E: Enterobacter species
48
Q

What drugs are used to treat Methicillin Resistant Staphylococcus Aureus?

A
  • Vancomycin
  • Linezolid
49
Q

What is the MOA of Vancomycin?

A

Binds to the D-Ala D-Ala dipeptide and inhibits transglycosylation reactions to prevent cell wall synthesis.

50
Q

What is the MOA of Linezolid?

A

Targets the 50S ribosome and inhibits initiation of protein synthesis

51
Q

What antibiotic treatment for pneumonia should be avoided because it is inactivated by pulmonary surfactant?

A

Daptomycin

52
Q

What pathogen causes infections that are common in individuals with cystic fibrosis and result in concern that chronic antibiotic treatment is not only selecting for drug resistance but also decreasing diversity of lung microbiome?

A

Pseudomonas aeruginosa

(hospital-acquired pneumonia)

53
Q

13% of hospital-acquired pneumonia cases due to Pseudomonas aeruginosa are Multidrug Resistant due to what resistance mechanisms?

A

efflux, biofilms, porins

54
Q

What are the appropriate antibiotic treatments for hospital-acquired pneumonia cases due to Pseudomonas aeruginosa?

A
  • Piperacillin/tazobactam
  • Cefepime (4th gen)
  • Imipenem/Cilastatin (for kidney protection)
  • Aztreonam
55
Q

A 45 year old man presents to the local hospital with headache, fever, malaise, and nonproductive cough. He became ill several days after hunting and moving brush outside of his cabin near Eagle River, WI. A fungal antigen test is positive. Which microorganisms is most likely responsible for his illness?

  • A. Actinomyces israelii
  • B. Blastomyces dermatitidis
  • C. Coccidioides immitis
  • D. Legionella pneumophila
  • E. Histoplasma capsulatum
A

B. Blastomyces dermatitidis

56
Q

How can you prevent Blastomyces dermatitidis infections?

A
  • Prevent exposure including in Middle/Eastern US:
    • spelunking (exploring caves)
    • demolition
    • clearing brush (especially rotting wood)
57
Q

What can you get Histoplasma capsulatum infections from?

A
  • Bat droppings
  • Mississippi/Ohio river valleys
58
Q

What can you get Coccidioides immitis infections from?

A
  • Endospores in spherule
  • SW US, dry climates
59
Q

How do you treat systemic fungal mycoses can disseminate to bones, joints, and CNS especially in immunosuppressed individuals

A

Amphotericin B and follow up with Itraconazole

60
Q

What is the MOA of Amphotericin B?

A

Binds ergosterol, creating holes in membrane allowing leakage of electrolytes

61
Q

What spectrum of pathogens can Amphotericin B be used to treat?

A

Used for invasive systemic fungal infections in immunocompromised patients.

Active against yeast and molds.

62
Q

What are the adverse side effects of Amphotericin B?

A
  • TOXIC because it is able to bind cholesterol.
  • Decreases renal blood flow and can lead to permanent destruction of the basement membrane.
  • 80% patients have nephrotoxicity
63
Q

What ubiquitous fungi in the environment primarily infects the lungs?

A

Aspergillus fumigatus

64
Q

What four respiratory conditions can Aspergillus fumigatus cause?

A
  1. Allergic bronchopulmonary aspergillosis- hypersensitivity
    • brown mucous plugs- containing fungi and eosinophils
    • asthma or cystic fibrosis
  2. Asperigillomas (fungal ball)
  3. Fungal sinusitis
  4. Systemic disease in immunocompromised
65
Q

How do you treat a system Aspergillus fumigatus infection?

A

If systemic treat with Voriconazole, but mortality rate is between 45 and 80 percent since patients are often neutropenic.

66
Q

Why might treatment with Prednisone be sufficient for Allergic bronchopulmonary aspergillosis (ABPS)?

A

Not worried about the infection part of it (benign bug), just want to eliminate inflammation!

67
Q

What is the MOA of Voriconazole?

A

Causes accumulation of toxic sterol:

binds fungal P-450 enzyme(Erg11) blocking the production of the membrane protein ergosterol and causing the accumulation of lanosterol (toxic)

68
Q

What are the two Azoles we need to know?

A
  • Voriconazole
  • Itraconazole
69
Q

What are the important toxicities associated with Azoles?

A
  • Drug-Drug interactions
  • hepatotoxicity
  • neurotoxicity
  • alters hormone synthesis
    • avoid during pregnancy
70
Q

What is the MOA of Azoles?

A

binds fungal P-450 enzyme(Erg11) blocking the production of the membrane protein ergosterol and causing the accumulation of lanosterol (toxic)

71
Q

Why should patients be careful with combination decongestants and anti-histamines?

A

They can have a drying effect making mucus thicker and harder to clear.

(Robitussin = dextromethorphan + guaifensin)

72
Q

Some Gram negative rods express extended spectrum beta-lactamases for which the only functional antibiotic is ______________?

A

Polymyxin E

73
Q

What agents can be used for symptomatic treatment?

A
  • Antitussive (dextromethorphan, codeine)- block cough reflex
  • Expectorant (Guaifenesin) or Acetylcysteine- thins mucus
  • Analgesic (paracetamol, ibuprofen)- fever/pain reliever
  • Decongestant (phenylepherine and pseudoephedrine)-constrict blood vessel in nasal membranes
  • H1 blockers-1st gen. chlorpheniramine (sleep aid), 2nd gen. loratadine, fexofenadine
  • Bronchodilator- Albuterol (beta2-agonist smaller airways), Ipratropium (anticholinergic- central airways)
  • Oxygen
  • Nebulized cold steam
  • Corticosteroids (Budesonide)- inhibits cytokine synthesis, reduce hospital stay but not death in pneumonia, increase likelihood of secondary infections

CRRAB II Week 8/9 - WLB (5 decks)

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