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Fall Pharm Block 4 > Anti-Infectives Part 3 > Flashcards

Anti-Infectives Part 3 Flashcards

1
Q

What is the brand name of the combo drug Trimethoprim and Sulfamethoxazole.

A

Bactrim

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2
Q

T/F: Bactrim is antigenic. Why?

A

True: it is a sulfa drug –> severe rashes

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3
Q

Describe the two types of dosing in which PO Bactrim is available.

A

SS: Single Strength –> 400 sulfameth./ 80 trimeth
DS: Double Strength –> 800 sulfameth./ 160 trimeth

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4
Q

Which dose of bactrim is most commonly used and by what routes is it available?

A

DS most commonly used –> available IV and PO

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5
Q

What drug in the Bactrim combination is the IV dosing based on?

A

Trimethoprim –> if the order says 500mg bactrim, we pull 500mg trimethoprim from the vial and whatever amount of sulfamethoxazole comes with it is just along for the ride.

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6
Q

Describe the mechanism of action of Bactrim.

A

Bacteria activate folate through several steps and use activated folate to make DNA. Both drugs in Bactrim inhibit a different step in the activation of folate.

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7
Q

What severe disease can a sulfa allergic rash rapidly progress to?

A

Stevens Johnson Syndrome

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8
Q

What are the signs and symptoms of Stevens Johnson Syndrome and what is the treatment?

A

Severe, burn-like rash treated by stopping the offending agent then administering steroids.

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9
Q

How do you differentiate a Stevens Johnson rash from a typical drug reaction rash?

A

S-J rash affects the mucus membranes where typical drug rashes do not.

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10
Q

What bacteria do Bactrim cover?

A

Hodge-podge of Gram pos and neg –> similar to macrolides and 2nd gen cefalosporins.

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11
Q

What are the major gaps in Bactrim coverage?

A

Pseudamonas and strep

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12
Q

What bacteria is Bactrim most efficacious against and what disease does this bacteria cause?

A

E. Choli –> UTIs. Typically we prescribe 3-5 days of Bactrim for an uncomplicated UTI. Complicated UTIs get 7-10 days of Bactrim.

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13
Q

Describe how Bactrim is useful in HIV patients.

A

Bactrim covers PCP. When an HIV Pt’s CD4 count falls < 200, we Px Bactrim prophylaxis against PCP pneumonia. PCP pneumonia treated with IV Bactrim.

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14
Q

T/F: Bactrim covers MRSA.

A

T: Bactrim covers community acquired MRSA

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15
Q

Differentiate a community acquired MRSA rash from another rash.

A

Community acquired MRSA rash is a papule (painful bumps) rash as opposed to a macular rash (flat rash).

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16
Q

Where is community acquired MRSA typically found?

A

Gyms and locker rooms

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17
Q

How many days of Bactrim is given to treat community acquired MRSA?

A

10-14 days of Bactrim DS –> 1 pill PO bid

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18
Q

T/F: Sulfa drugs are highly plasma protein bound.

A

True

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19
Q

Describe the use of Bactrim and other sulfa drugs in pregnancy.

A

Don’t use sulfa drugs in pregnancy. Sulfa drugs displace bilirubin from albuminin in the fetus causing hyperbilirubinemia, leading to Kernicterus (mental retardation).

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20
Q

What condition is common in pregnancy that might tempt a clinician to prescribe Bactrim?

A

UTIs

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21
Q

What is a side effect of sulfa drugs and how do we treat it?

A

Photosensitivity –> use sun block that protects against UVA and UVB rays.

22
Q

What bacteria do metronidazole cover?

A

anaerobes, trichomonas, and giarrhdea (dirty water).

23
Q

What two places in the body are anaerobes commonly found?

A

Colon and mouth (they hide below the gum line and between the teeth)

24
Q

Describe the mechanism that prevents people on metranidazole from consuming alcohol.

A

ETOH (via alcohol dehydrogenase) is broken down to Acetal Aldehyde which is then (via Aldehyde Dehydrogenase) broken down into CO2, H2O, and Acetyl CoA. Metranidazole inhibits aldehyde dehydrogenase. Acetyl aldehyde then builds up causing rash, nausea, and vomiting.

25
Q

Describe the mechanism of action of disulfiram and its use.

A

Aldehyde dehydrogenase inhibitor. It used to be given to alcoholics to make them sick every time they drank and theoretically make them stop drinking.

26
Q

What prescription drug inhibits alcohol dehydrogenase? What is its legitimate use and what is its criminal use?

A

Chlorylhydrate. It is a sedative used for insomnia that criminals use as a date rape drug.

27
Q

What bacteria does Clindamycin cover?

A

Gram pos and anaerobes –> no Gram neg coverage

28
Q

Compare and contrast clindamycin to vancomycin.

A

Clinda covers anaerobes where vanc doesn’t. Not as good at gram pos as vanc. It’s similar to vanc in that it doesn’t cover gram neg at all.

29
Q

What two skin conditions have clindamycin been used to treat. What other abx treats one of these conditions.

A

Abscess - clinda excellent at penetrating abscesses

Acne - clinda covers the bacteria that causes acne. Minocycline is also used to treat acne.

30
Q

What medical specialty loves clindamycin and why?

A

Dentists - used for dental abscesses bc clinda penetrates and covers anaerobes.

31
Q

What abx is the biggest cause of C. Diff and why?

A

Clindamycin - it kills anaerobes (kills normal gut flora)

32
Q

By what route is mupirocin administered and for what condition is it commonly used?

A

Topical only - de-colonize people that are colonized with MRSA. Colonization in nares mostly.

33
Q

What bacteria do linezolid cover?

A

MRSA and VRE

34
Q

What is unique about linezolid’s kinetics and how is this clinically relevant?

A

Near 100% bioavailability. May allow for out-patient treatment of hospital acquired MRSA.

35
Q

What are the AEs of linezolid and what is the clinical relevance of each?

A

Thrombocytopenia - must monitor platelets

Weak MAOI - caution when administering with SSRIs

36
Q

What OTC anti-depressant is a weak SSRI?

A

St. John’s Wort

37
Q

What drug is second line for community acquired MRSA (esp if allergic to bactrim)?

A

Clindamycin

38
Q

What bacteria do aminoglycosides cover?

A

Gram neg including pseudamonas with SOME coverage of enterococcus.

39
Q

How are aminoglycosides typically used in the treatment of pseudamonas?

A

As an add-on agent if you want to double cover for pseudamonas.

40
Q

By what route are amininoglycsides administered and why? Why else is this clinically relevant to their use?

A

IV - very hydrophilic. Also means they have poor CNS and urinary penetration.

41
Q

What are the AEs of aminoglycosides?

A

Nephrotoxicity and Ototoxicity

42
Q

What are the two most commonly used amoniglycosides? What is another aminoglycoside?

A

Gentamicin and Tobramycin - most common

Neomycin - other

43
Q

By what routes are Neomycin available and why only those? What is neomycin used for?

A

Topical: ingredient in Neosporin
PO: treatment of hepatic encephalopathy
Too toxic to be given IV

44
Q

What is the mechanism by which neomycin is used for hepatic encephalopathy?

A

Much of the ammonia (causes hep enceph) that gets in the blood is produced by bacteria in the colon. Neomycin decreases colon bacteria and thereby decreases ammonia production.

45
Q

What is a second, non-abx way to treat hepatic encephalopathy?

A

Lactulose - acidifies the colon making it more hydrophilic, and thus, dec ammonia absorption.

46
Q

What is the pathophysiology of hepatic encephalopathy?

A

Protein is broken down in GI with ammonia as a by-product. The liver binds a ketone to 2 ammonia molecules to make urea. Cirrhotic liver can’t make urea and excess ammonia causes hepatic encephalopathy because ammonia mimics GABA (sedation).

47
Q

T/F: Allergies to aminoglycosides are common.

A

False: extremely rare

48
Q

Name an additional abx used to treat hepatic encephalopathy.

A

Rifaximin

49
Q

What is the primary use of rifaximin?

A

Traveler’s diarrhea caused by E. Coli, Giardia, etc.

50
Q

What is the primary use of Nitrofurantoin?

A

UTIs - in pregnancy and prophylactically in SNFs.

51
Q

Why is Nitrofurantoin used in UTI in pregnancy?

A

Because we can’t use Bactrim for UTIs in pregnancy because bactrim causes fetal hyperbilirubinemia.

52
Q

What is a strange AE of Nitrofurantoin?

A

Long term use can cause pulmonary fibrosis.

Fall Pharm Block 4 (4 decks)

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