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Microbiology Part 1 > Lec21 Case Based Review of Antibiotics > Flashcards

Lec21 Case Based Review of Antibiotics Flashcards

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1
Q

What is drug of choice for scarlet fever?

A

penicillin or amoxicillin [for strep A]

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2
Q

Which of these is a common side effect of penicillin?

A. allergic rxn
B. bile sludging
C. ototoxicity
D. QTc prolongation
E. tendonitis
A

A. allergic rxn

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3
Q

Which of these is a common side effect of ceftriaxone?

A. allergic rxn
B. bile sludging
C. ototoxicity
D. QTc prolongation
E. tendonitis
A

B. bile sludging

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4
Q

Which of these is a common side effect of aminoglycosides?

A. allergic rxn
B. bile sludging
C. ototoxicity
D. QTc prolongation
E. tendonitis
A

C. ototoxicity

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5
Q

Which of these is a common side effect of azithromycin?

A. allergic rxn
B. bile sludging
C. ototoxicity
D. QTc prolongation
E. tendonitis
A

D. QTc prolongation

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6
Q

Which of these are common side effects of fluoroquinolones?

A. allergic rxn
B. bile sludging
C. ototoxicity
D. QTc prolongation
E. tendonitis
A

QTc prolongation and tenodinits

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7
Q

How do you differentiate allergic rash vs rash not related to antibiotic?

A

allergic rash will have hives

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8
Q

What is the most important cause of septic arthritis?

A

staph aureus

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9
Q

What is empiric treatment for septic arthritis of the following

A. ceftriaxone
B. cephalexin
C. Nafcillin
D. piperacillin-tazobactam
E. vancomycin
A

C. nafcillin

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10
Q

What is mech of MRSA being reisistant?

A

altered PBP

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11
Q

What are 5 antibiotics most active against MRSA? 3 others that are pretty active?

A

most active

  • vancomycin = first line
  • daptomycin
  • linezolid
  • ceftaroline = only cephalosporin active against MRSA

pretty active

  • clindamycin
  • doxycycline
  • trimethoprim-sulfamethoxazole
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12
Q

How is vancomycin administered? side effects? mech of action?

A

administered: IV

side effects: red man syndrome, nephrotoxicity

action: inhibits polymerization peptidoglycan

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13
Q

How is daptomycin administered? side effects? mech of action?

A

administered: IV

side effects: myositis, CPK elevation

action: disrupts bacterial membrane
notes: not active in lung because inactivated by surfactant

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14
Q

How is linezolid administered? side effects? mech of action?

A

administered: oral or IV [100% bioavaialbility]

side effects: bone marrow suppression, low platelets, serotonin syndrome

action: protein synthesis inhibitor
note: costly

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15
Q

How is clindamycin administered? mech of action?

A

administered: oral [good bioavailability]
action: protein synthesis inhibitor
note: excellent penetration to bone [good for osteomyelitis]

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16
Q

How is doxycycline administered? side effects? mech of action?

A

administered: oral, but absorption inhibited by Ca, Mg, dairy, antacids

side effects: photosensitivity, GI intolerance, staining of teeth in children

action: protein synthesis inhibitor [a tetracycline]

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17
Q

What is mech of action of trimethoprim-sulfmethoxazole administered? side effects?

A

side effects: steven-johnson syndrome = rash and blisters all over body, bone marrow suppression, kern-icterus in infants

action: folate pathway inhibitor

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18
Q

Which of the following is best definitive treatment for MSSA? Why?

A. amoxicillin
B. azythromycin
C. cefazolin
D. cefepime
E. penecillin
A

C. cefazolin

s. aureus usually produces penicillinase –> best to treat with penicillinase stable penicillin [nafcillin] or 1st gen cephalosporin [cefazolin, cephalexin]

other active but unnecessarily broad treatments:
4th gen cephalosporins: cefepime
5th gen: ceftaroline
beta lacam + betalactamase combo

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19
Q

What are the 3 beta lactam + betalactamase inhibitor combos?

A

Amoxicillin-clavulanic

Ampicillin-sulbactam

Piperacillin-tazobactam

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20
Q

What is empiric antibiotic regimen for infant with meningitis?

A

vancomycin + ceftriazone

vanc = some strains of strep pneumo resistant to cetriaxone
ceft = strep pneumo, neisseria, h. influenzae
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21
Q

who gets listeria?

A

less than 1 month
pregnant
immunocompromised

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22
Q

What are causes of bacterial meningitis for less than 1 month old? empiric treatment?

A

GBS, E Coli, Listeria

treat: ampicillin + cefotaxime

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23
Q

What are causes of bacterial meningitis for 1 month to adulthood? empiric treatment?

A

N. meningitidis, S. pneumoniae, H. influenza type B

treat: cetriaxone + vancomycin

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24
Q

What are causes of bacterial meningitis in immunocompromised and pregnant? empiric treatment?

A

N. meningitidis, S. pneimoniae, H. influenzae type B, Listeria

treat: ceftriaxone + vancomycin + ampicillin

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25
Q

If you have kid with s pneumoniae meningitis which of the following would you choose to treat it?

A. ampicillin
B. cefazolin
C. cefuroxime
D. clindamycin

A

A. ampicillin

1st and 2nd gen cephalosporins don’t penetrate CNS [cefazlin, cefuroxime]

clindamycin = bacteriostatic so not strong enough for meningitis [prefer bacteridicidal since so serious], also doesn’t have great ability to penetrate CNS

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26
Q

What are the two first gen cephalosporins? how are they administered? what do they treat? Can they penetrate CNS?

A

cefazolin [IV], cephalexin [PO = oral]

  • gram pos but not MRSA or enterococcus
  • some gram neg [some E Coli, K pneumoniae]

= best cephalosporins for MSSA

Can’t penentrate CNS

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27
Q

What are the 3 main second gen cephalosporins? how are they administered? what do they treat? Can they penetrate CNS?

A

Cefuroxime [IV or PO], Cefoxitin, Cefotetan

treat:

  • 1st gen spectrum + broader gram negative
  • treat H. influenzae [sinusitis, otitis media]
  • cefoxitin and cefotetan = only 2nd gen cephs with anaerobic spectrum

do not penetrate CNS

28
Q

What are the main third gen cephalosporins? how are they administered? what do they treat? Can they penetrate CNS?

A

Ceftriazone [IV or IM], Cefotaxime [IV or IM]

  • activity against most community acquired, broader gram neg than 1st or 2nd gen
  • some s. pneumoniae are resistant
  • no MRSA, enterococcus, pseudomonas, anaerobes
  • penetrate all tissues including CNS
  • good empiric treat for meningitis, pneumonia, urinary infections
29
Q

What is side effect of ceftriaxone? who should avoid?

A
  • can get bile sludging because excreted in bile

- avoid in infants and people with liver disease

30
Q

What kind of coverage does ceftazidime have?

A
  • no gram positive coverage

- good for pseudomonas

31
Q

Is half life longer for ceftriaxone or cefotaxime?

A

ceftriaxone = longer half life, 1-2 daily admin

cefotaxime = shorter half life, 3x a day administration

32
Q

What type of antibiotic used to empirically treat patient with leukemia, neutropenia? Hint: at high risk for bacterial sepsis including from pseudomonas?

A
  • beta lactam with activity against gram +/gram-/pseudomonas
  • levofloxacin
  • add vancomycin to either if concerned for MRSA
33
Q

What are betalactams with activity against psuedomonas?

A

penicillins: piperacillin +/- tazobactam, ticaracillin +/- clavulanic
cephalosporins: ceftazidime [3rd gen], cefepime [4th gen]
carbapenems: doripenem, imipenem-cilastatin, meropenem
monobactams: aztreonam

34
Q

What is aztreonam useful against?

A
  • against pseudomonas
  • no gram + activity
  • good for pt with beta-lactam allergy
35
Q

what is ceftazidime useful against?

A
  • against pseudomonas

- no gram + activity

36
Q

What is cefepime active against? how is it administered?

A
  • IV administration

treats:

  • same gram post coverage of 1st gen cephalosporins [no MRSA or enterococcus]
  • same gram neg coverage of 3rd gen cephalosporins
  • pseudomonas
  • other nosocomial gram neg
37
Q

Why is shortcoming of piperacillin-tazobactam?

A

not good CNS penetration = don’t use for meningitis

38
Q

What is imipenem [and carbapenems] active against? how is it administered? side effect?

A
  • IV administration

treats:

  • gram pos [no MRSA]
  • gram neg [including borader nosocomial coverage than cefepime]
  • anaerobes

side effect: associated with seizures

39
Q

What are side effects of fluorquinolones? safe for kids? bioavailability? CNS penetration?

A
  • side effect: tendonitis, QTc prolongation, CNS symptoms
  • not first line drug for kids –> concern about effect on bone growth
  • good bioavailability can give PO or IV
  • good CNS penetration
40
Q

What is mech of resistance to fluoroquinolones?

A

resistance by mutation in topoisomerase or DNA gyrase

41
Q

What can ciprofloxacin treat of the following?

A. gram negative [including pseudomonas]
B. gram pos [MRSA and enterococcus not consistently]
C. anaerobes
D. atypicals [mycoplasma, chlamydia, legionella]

A

Yes: A and D

A. gram negative [including pseudomonas]
D. atypicals [mycoplasma, chlamydia, legionella]

Not:
B. gram pos [MRSA and enterococcus not consistently]
C. anaerobes

42
Q

What can levofloxacin treat of the following?

A. gram negative [including pseudomonas]
B. gram pos [MRSA and enterococcus not consistently]
C. anaerobes
D. atypicals [mycoplasma, chlamydia, legionella]

A

Yes: A, B, and D

A. gram negative [including pseudomonas]
B. gram pos [MRSA and enterococcus not consistently]
D. atypicals [mycoplasma, chlamydia, legionella]

Not:
C. anaerobes

43
Q

What can moxifloxacin treat of the following

A. gram negative [including pseudomonas]
B. gram pos [MRSA and enterococcus not consistently]
C. anaerobes
D. atypicals [mycoplasma, chlamydia, legionella]

A

All!

44
Q

What is mech of action of aminoglycosides? Activity? side effects? CNS penetration?

A

mech: protein synthesis inhibitors

activity:

  • mostly gram negatives, usully not used as single agents
  • can be synergistic against some gram pos [with ampicillin against enterococcus]

side effects:

  • ototoxic [auditory and vestibular]
  • nephrotoxic

No CNS penetration!

45
Q

What are the 3 aminoglycosides? what is broadest?

A
  • Gentamicin
  • tobramycin
  • amikacin = broadest
46
Q

What organism would you guess from:
24 yo male with AML, fever, neutropenia, on Cefepime. fever persisted and culture on day 6 grows gram + cocci in pairs and short chains

A

enterococci because gram + pairs and short chains that are common nosocomial pathogens and are not treatable by cephalosporins

47
Q

What is the empiric treatment for serious enterococci infection? If resistant to this?

A
  • vancomycin

- if resistant [VRE] use linezolid or daptomycin

48
Q

What is the first line drug for susceptible enterococci strains?

A

ampicillin

49
Q

What drugs cannot treat enterococci?

A
  • cephalosporins have no activity
  • fluoroquinolones have poor activity
  • aminoglycosides have no activity on their own
50
Q

What can ceftaroline treat?

A
  • gram pos including MRSA
  • gram neg narrower than 4th gen
  • cannot treat pseudomonas or other resistant nosocomial negatives
51
Q 
Which of the following to treat pt with C difficile colitis?
A. Ampicillin-sulbactam
B. Piperacillin-tazobactam
C. Imipenem
D. Cefotetan
E. Clindamycin
F. Metronidazole
A

F. metronidazole

52
Q

What can metronidazole treat? mech? type of administration? side effects?

A

treat: anaerobic bacteria, some parasites
mech: causes DNA damage
administration: IV or PO

side effects: disulfiram effect [vomiting, ab pain, headache combined with alcohol], metallic taste, CNS side effects

53
Q

What can oral vancomycin be used to treat?

A
  • C difficile colitis

- second line drug because of concerns for selection of VRE and cost

54
Q

Clinical: pt on day 7 of levofloxacin treatment of pneumonia presents with fever, ab main, foul-smelling bloody loose bowel movements

What should you think?

A

C Diff colitis

55
Q

What is cause of intra-abdominal abscess?

A

usually polymicrobial

  • anaerobes, enteric gram neg, enterococcus, anaerobic streptococci
56
Q

What treatment for intra-abdominal abscess?

A
  • cephalosporin [for gram -] + metronidazole [for anaerobes]
  • beta lactam/beta lactamase inhibitor
  • carbapenem

also drain abscess

57
Q

In order which is best for gram neg between: pip/tazo, imipenem, amp/sulbactam?

A

imipenem > pip/tazo > amp/sulbactam

58
Q

Match the four main causes of pneumonia with the clinical situations?

A. most common
B. common after flu
C. common in COPD
D. common in alcoholic pt, older pts

A 
A = s. pneumoniae
B = s. aureus
C = h. influenzae
D = k. pneumoniae
59
Q

What are causes of walking pneumonia?

A
  • mycoplasma
  • chlamydia
  • legionella [sicker pts]
  • viruses
60
Q

How do you treat walking pneumonia?

A
  • azithromycin

- fluoroquinolones [levofloxacin]

61
Q

Treatment for v. sick pneumonia pt [inpatient]?

A
  • ceftrioxone [to cover typicals] and azithromycin [to cover atypicals]
  • levofloxacin
  • if S aureus suspected –> vancomycin
62
Q

Treatment for outpatient pneumonia?

A
  • levofloxacin [for lobar PNA and atypicals]

- amoxicillin +/- azithromycin [preferred for peds]

63
Q

What are the 3 macrolides?

A
  • azithromycin
  • clarithromycin
  • erythromycin
64
Q

What is a side effect unique to clarithromycin and erythromycin?

A

CP450 inhibitors, can elevate levels of drugs metabolized through that pathway

65
Q

What are side effects of the macrolides?

A

all: QTc prolongation
erythromycin: GI discomfort
clarithro + erythro: CP450 inhibitors –> elevate levels of drugs metabolized through that pathway

Microbiology Part 1 (24 decks)

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