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Antibiotics lectures Flashcards

1
Q

Gram stain vs. Culture/sensitivity

A

Gram stain: G+/- ; coccyx or bacilli; petidoglycan +/-

C&S: tells you specific organism; quantifies amount of bacteria in the sample, what ABx the organism is sensitive to , resistant to, etc.

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2
Q

Choosing appropriate ABx

3 factors

A

Pathogen: antimicrobial spectrum of activity, susceptibility testing, local susceptibility patterns (can vary w/in local area or even w/in a hospital; ANTIBIOGRAM: which drugs on formulary an organism is sensitive/resistant to)

Drug factors: clinical efficacy, pharmacokinetics
Pt factors: age, hepatic/renal fxn (dose adjustments), allergies, pregnancy, cost

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3
Q

Fevers

  • Causes
  • Drug fever
  • Antipyretics
A
  • Hallmark of infectious dz but not always present (UTI)
  • Autoimmune DOs, malignancy
  • Drug fever: MC: B-lactam ABx, anticonvulsants, sulfonamides, etc; disappears w/in 48 hrs once meds are stopped
  • Antipyretics CAN MASK RESPONSE TO TX – avoid if possible (see fever go away spontaneously w/ ABx)
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4
Q

WBCs

  • Cause of increase
  • Findings
A
  • Increased w/ infection; can also be d/t major surgery, M.I., leukemia, corticosteroids
  • May be normal (UTI) or low (neutropenia)
  • “Left shift” = immature WBCs –> bone marrow suppression
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5
Q

Pt is brought into ICU for emergency bowl resection, intubated; Day 20 becomes hypotensive, tachycardic, cold extremities, circumoral pallor, feverish, tachypneic, w/ increased sputum. P.E incl: sinus tachy, rhonchi w/ decreased breath sounds, distended abd/ new abd pain, absent bowel sounds, guaiac +; decreased urine outflow, elevated SCr; erythema at CVC site; CXR shows LL infiltrates; bands present on CBC
What are the sxs of infection?

A
  • Fever
  • B/L infiltrates on CXR
  • Copious amts of sputum from ET tube (yellow-green)
  • Erythema around catheter/ wound
  • Increased ESR: not specific to infection
  • Confusion
  • WBCs in urinalysis; bands
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6
Q

What are the sxs of sepsis/ septic shock in the Pt above?

A
  • Hypotension
  • Glucose intolerance
  • Tachypnea, tachycardia
  • DIC: decreased Plt count, & PTtime
  • Decreased urine outflow, elevated SCr = renal failure
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7
Q

Possible sites of infection in Pt scenario?

A
  • Pna: d/t CXR, sputum production, tachypnea
  • Intra-abdominal: recent surgery, abd pain/ distention, absent bowel sounds
  • Urinary tract: abnml urinalysis w/ WBCs
  • CVC: erythema
  • Blood
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8
Q

MC organisms for:

  • Pna
  • Intra-abd
  • G.U
  • CVC
A
  • (MR)SA, Pseudomonas, Klebsiella
  • Bacteroides fragilis, E.coli, Enterococci
  • E.coli, Klebsiella, Staph
  • CVC: Staph
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9
Q

Identifying infected pathogen

A
  • Obtain samples PRIOR to starting ABx (to avoid false (-))
  • Perform BCx in all acutely ill febrile pts
  • For Pt case: sputum cx, urine, blood, drainage from wound, cx of catheter tip if easily removed
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10
Q

Gram positive bacteria examples

A 
Strep pneumococcus, viridans, GAS
Enterococcus
Staph aureus, epidermidis
Corynebacterium
Listeria
Clostridium
P. acnes
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11
Q

Gram negative bacteria examples

A 
Moraxella
Neisseria
Enterobacteria (E.coli, Klebsiella, salmonella, shigella)
Camphlyobacter
Pseudomonas
Helicobacter
Hemophilus
Bacteroides
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12
Q

Atypical bacteria

A

Chlamydia

Mycoplasma

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13
Q

Special considerations for cx results

A
  • Colonization vs. infection vs. contamination
  • Sputum cx: epithelial cells = bad sample
  • Recovery of S. epidermidis or Corynebacterium from normally sterile sample (blood, CSF, jt fluid) could mean contamination (not found on skin); proper collection is key
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14
Q

Infection vs. Colonization vs. Contamination

A

Infection: isolated organisms from the specimen, causing infection

Colonization: organisms from the specimen are NOT causing symptoms (potential to cause infection, but not implicated; if disproportionaltely high, more likely cause)

Contamination: isolated organisms came from the pt’s skin or environment

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15
Q

Culture/ Sensitivity Report

A
  • Final ID of organism/ quantity & info on effectiveness of antimicrobials
  • Results in 24-48 hrs: reported as S (sensitive) R (resistant) or I (intermed); M.I.C will be listed
  • ABx on formulary will be listed
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16
Q

Choosing ABx based on pathogen:

-Considerations of spectrum of activity, susceptibility, local susceptibility patterns

A
  • MIC: the lowest [antimicrobial] that prevents visible growth of an organism
  • Susceptible = MIC < attainable serum levels = you can treat the infection
  • Intermed = MIC = attainable serum levels = you may not be able to treat enough unless the drug is safe in [higher] or if drug will stay at site
  • Reistant = MIC > attainable serum levels = can’t get enough drug into pt
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17
Q

Choosing ABx based on drug factors

A

Efficacy: does it reach the infection area – i.e solubility

P’kinetics & P’dynamics: determine dose & interval – time-dependent killers vs. [ ] - dependent killers

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18
Q

Time-dependent killers

A

Dependent on the time an organism is in contact with the drug; duration that the [drug] is above MIC is important i.e. B-lactams, vancomycin

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19
Q

Concentration-dependent killers

A

Dependent on the [drug] that the organism is exposed to; higher [ ] = greater killing; peak serum drug concentration: MIC; i.e. fluoroquinolones, aminoglycosides

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20
Q

Synergy & Post-antibiotic effect (PAE)

A

Synergy: using 2 ABx together has synergistic effects (can be determined w/ lab tests)

PAE: growth is suppressed for a period of time AFTER the [drug] falls below MIC i.e. aminoglycosides which can be dosed QD

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21
Q

Patient factors

  • Age
  • DIs
  • Hepatic/ renal impairment
  • Pregnancy
A
  • Elderly: decreased functioning nephrons/ decreased renal fxn
  • Neonates: kernicterus post-sulfonamide admin
  • Concomitant meds: i.e. warfarin, OCPs?
  • Impairments may require dose adjustment
  • Meds may be cleared at a rate of 50% FASTER; may need INCREASE in dose; some meds TERATOGENIC
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22
Q

Pt factors

  • Allergies
  • Cost
  • Route
  • Compliance
A
  • Common ADEs confused as allergies; most reported is PCN allergy – best to avoid if true anaphylaxis (avoid cross-reactive drugs like cephalosporins, carbapenams too)
  • Newer ABx = more expensive, not much more effective; some require monitoring = added cost
  • Route: PO preferred but IV necessary for severe; most pts can be switched to PO once stable/afebrile & improving
  • with QID dosing, pt may be less compliant
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23
Q

Intrinsic vs. Acquired resistance

A
  • Intrinsic: naturally-occurring resistance (i.e. drug can’t penetrate cell wall)
  • Acquired: normally sensitive becomes resistant
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24
Q

Mechanisms of acquired resistance

A
  • Detoxifying enzymes: alter ABx structure, fxn e.g. B-lactamase that breaks down the B-lactam ring
  • Alteration in ABx target site: e.g. PCN binding protein
  • Decreased cellular accumulation of ABx: e.g. decreased permeability, increased efflux
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25
Q

Common B-lactamase

  • Against which drugs
  • Inhibited by B-lactamase inhibitor?
  • Which bacteria
A
  • PCNs, 1st gen cephalosporins, 2nd gen cephalosporins
  • Yes
  • E.coli, Proteus, Staphylococcus
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26
Q

ESBL

  • Against which drugs
  • Inhibited by B-lactamase Inhibitors?
  • Which bacteria
A
  • PCNs, Cephalosporins; NEED carbapenams
  • Some
  • Klebsiella pna; some E.coli
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27
Q

Amp C/ Plasmid-mediated Amp C

  • Against which drugs
  • Inhibited by B-lactamase Inhibitors?
  • Which bacteria
A
  • PCNs, Cephalosporins; NEED carbapenams
  • No
  • Pseudomonas; Enterobacter; Klebsiella pna
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28
Q

IV vs. PO therapy

-Uses; advantages

A

IV: for severe infections (at least initially); when pt cannot tolerate PO or is NPO

PO: many ABx have excellent bioavailability & should be given unless 1 of the above is present –
decreased cost; utilizes less resources/ personnel time; preferred by pt; reduced exposure of nosocomial infxns/ phlebitis; increased mobility of pt; potential for earlier d/c

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29
Q

Penicillins (& aminopenicillins-mostly IV)

  • Examples
  • General spectrum of activity
  • Common uses
A
  • PCN VK, PCN G; ampicillin, amoxicillin
  • Streptococcus, T. pallidum (syphilis)
  • MC for pharyngitis, ERYSIPELAS, syphilis; NOT FOR STAPH
  • Amoxicillin for URIs, OM ; drug of choice for susceptible Enterococcal infections; Amoxicillin/clavulanate for skin infxns, urinary tract infxns, CAP, lymphadenitis
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30
Q

PCNase-resistant PCN (dicloxacillin, nafcillin, oxacillin)

  • Examples
  • General spectrum of activity
  • Common uses

Extended-Spectrum PCNs (B-lactamase inhibitors)

  • Examples
  • General spectrum of activity
  • Common uses
A
  • Dicloxacillin, Nafcillin, oxacillin
  • Staph, Strep: drug of choice for B-lactamase producing staph
  • Tx of CELLULITIS, mild-moderate diabetic foot infxn, endocarditis
  • Ticarcillin/clavulanate; Piperacillin/ tazobactam
  • Staph, Strep; Enterobacteriaeae, bacteroides
  • Tx of nosocomial pna, intra-abdominal infxn, skin/soft tissue infxn
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31
Q

B-lactamase Inhibitors

  • Action
  • Examples
  • Spectrum of activity
A
  • Enhances antimicrobial activity against certain B-lactamase producing organisms (extends spectrum)
  • Clavulanate, tazo-/sulbactam
  • G+ = S. aureus; G(-) = H.influenzae, E.coli, Klebsiella, Neisseria, Moraxella, bacteroides
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32
Q

Adverse Reactions to PCN

  • Rash
  • Anaphylaxis
  • Interstitial nephritis
  • Positive Coombs Test
  • Leukocytopenia/thrombocytopenia
  • Colitis
  • G.I upset/ diarrhea
  • Reversible hepatitis
A
  • Maculopapular or urticarial rash; MC WITH AMPICILLIN or in pts w/ mono/ w/in first 24 hrs
  • Anaphylaxis (rare), angioedema
  • Interstitial nephritis: esp methicillin, nafcillin (usually reversible)
  • Coombs test: with hemolytic anemia (rare; high doses)
  • C. difficile associated colitis: killing the good bacteria
  • Ampicillin/ amoxicillin (esp w/ clavulanate) – watch for dehydration
  • Nafcillin/ oxacillin (esp w/ endocarditis which requires long-term tx) MONITOR LFTs
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33
Q

Jarisch-Herxheimer rxn

A
  • With tx of spirochetal infections (i.e. Lyme)
  • Fever, chills, myalgia: continue w/ therapy
  • Reaction d/t release of lg amts of toxins after bacterial killing – continue therapy
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34
Q

PCN Allergy/ Desensitization

A
  • Only 10-20% of people who claimed to be allergic have a + skin test
  • Obtain detailed description/ timing of the symptoms of a reaction
  • Ask the pt which ABx they have tolerated in the past
  • For true PCN allergy you can perform desensitization if use is necessary
35
Q

4 Options for PCN Allergy

A
  1. Admin a cephalosporin (NON-THREATENING RXNS) – consider cross-reaction d/t structure
  2. Prescribe/ recommend a non-B-lactam ABx: macrolide, quinolone, sufonamides, vanco if proven sensitivity
  3. Perform desensitization – tiny dose is administered, followed by [higher] every 15-30 min until full dose given – done in the ICU in case of anaphylaxis; resensitized w/in 24 hrs
  4. Perform a PCN skin test
36
Q

Special Considerations for PCN

A
  • Monitor: renal, hepatic fxns; CBC if underlyindz or long-term tx
  • Most admin with empty stomach
  • Probenecid will decrease PCN secretion & increase [ ]
  • Methotrexate secretion is inhibited, may results in higher drug levels & toxicity
37
Q

Which of the following antibiotics would be the best choice for tx of cellulitis caused by MSSA?

a. Amoxicillin
b. Piperacillin/tazobactam
c. Penicillin
d. Nafcillin

A

d. Nafcillin

38
Q

1st and 2nd generation Cephalosporins

A

Cephalexin (PO)
Cefazolin (IV)

Cefuroxime (PO)
Cefoxitin (IV)

39
Q

3rd, 4th gen & newer generation Cephalosporins

A

Cefpodoxime (PO)
Ceftriaxone (IV)

Cefepime (IV)

Ceftaroline (IV) – advantage is activity against MRSA, VRSA, VISA

40
Q

Cephalosporin activity

A

Less susceptible to B-lactamase; broader spectrum compared to PCNs (incl Staph)

  • Earlier gens = better G(+) coverage
  • Later gens = better G (-) coverage
41
Q

1st generation Cephalosporins

  • General spectrum of activity –> SSPEcK
  • Common uses
A
  • Staph/Strep; Proteus; E.coli; Klebsiella

- UTI, pharyngitis, MILD skin/ soft tissue infections; URI, LRT

42
Q

2nd gen Cephalosporins

  • General spectrum of activity –> HMSSPEcK
  • Common uses
A
  • Haemophilus, Moraxella, Staph/Strep; Proteus, E.coli, Klebsiella
  • Sinusitis, pharyngitis, OM, lyme dz (cefuroxime); cefoxitin & cefotetan also have anaerobic coverage (Bacteroides): intrabdominal, G.U. (IV only)
43
Q

3rd gen Cephalosporins

  • General spectrum of activity
  • Common uses
A
  • Strep; Enterbacteria, H.flu
  • CAP (ceftriaxone, IV only - helpful for children refractory for PO ABx); OM, URI; Ceftazidime against Pseudomonas
  • ALL AGENTS EXCEPT CEFTRIAXONE REQUIRE RENAL DOSE ADJUSTMENT
44
Q

4th gen Cephalosporins

  • General spectrum of activity
  • Common uses
A
  • Strep/Staph; Enterobacteria, H.flu, Moraxella, Pseudomonas; Bacteroides – broader range, good for empiric tx
  • Meningitis, pna, nosocomial infections
45
Q

Special Considerations (similar to PCNs)

  • ADEs
  • Monitoring
  • Food
  • DIs
A

-Cefixime (G.I. effects) vs. Cefprozil (lowest incidence of diarrhea)
Cefaclor (rash); Cefotetan (hypoprothrombinemia - bleeding; disulfiram-like rxn)
-Monitor renal fxn
-Some taken with food
-DIs: Probenicid may INCREASE [cephalosporin]

46
Q

Cross-sensitivity of Cephalosporins & PCN

A
  • Use with caution in pts with a PCN allergy! overall rate of rxn is ~1%
  • Pts are at a higher risk of having a rxn with 1st gen!
  • Pts with a + PCN skin test may be at higher risk; no skin test for cephalosporin allergy (avoid w/ anaphylactic pts)
47
Q

Monobactam: Aztreonam

  • Coverage
  • Use
  • Cross-sensitivity?
  • Route, considerations
A
  • HAS ONLY G (-) COVERAGE incl. Pseudomonas (No G(+) or anaerobes)
  • Good for resistant infections (resistant to many B-lactamases produced by G(-))
  • No cross-sensitivity w/ PCN/ cephalosporin allergies
  • IV/IM admin
  • Doses adjusted for decreased renal fxn
  • Low incidence of ADEs – diarrhea
48
Q

Carbapenams

  • Coverage
  • Use
  • Cross-sensitivity?
  • ADEs, considerations
A
  • Strep/Staph; Listeria, G(-), anaerobes; most cover Pseudomonas – broad
  • Resistant to most B-lactamases; drug of choice for ESBL infections (LAST RESORT); urinary tract, LRT, intra-abdominal, gynecologic, skin/soft tissue, bone/joint
  • Cross-sensitive w/ PCN allergy
  • ADEs: N/V, seizures (high with imipenem & pts w/ renal failure);
  • Imipenem combined with cilastatin to prevent breakdown by renal enzymes
  • Renal adjustment
49
Q 
Glycopeptide ABx (Vancomycin, Telavancin)
-Action
A

Prevents cross-linking of cell wall peptidoglycan during cell wall synthesis

50
Q

Vancomyin

  • Coverage
  • Use
  • Route/ Dosing
  • Monitoring
  • ADEs
A
  • G(+) coverage only
  • MRSA INFECTIONS: sepsis, endocarditis, meningitis, skin/soft tissue infections (caution d/t VISA, VRSA)

-PO dosage is not absorbed – for C.diff ONLY
Dosing is variable: based on actual body wt, renal fxn

-Monitor serum levels once steady state is reached; trough levels measured (must be > 10-20mcg/ml) to prevent resistance!; renal fxn tests DAILY

-ADEs: ototoxicity; nephrotoxicity; injection site rxns
Risk of nephrotoxicity increased w/ other nephrotoxic drugs (i.e. aminoglycosides)

51
Q

Red Man Syndrome

  • Cause
  • Presentation
  • Management
A
  • Infusion-related rxn caused by histamine release; NOT AN ALLERGIC RXN
  • Erythematous or urticarial rxns, flushing, tachycardia, hypotension
  • Stop the infusion, wait for rxn to subside; slow infusion rate (<1 gm/hr or longer) may administer Benadryl prior to infusion; increased risk every time Vanco is used
52
Q

Telavancin

  • Dosing
  • Black box warning
  • Indications
  • ADEs
A
  • Dosed QD; adjusted for renal fxn
  • May cause ABNORMAL FETAL DEVELOPMENT: perform pregnancy test in women of child-bearing age
  • For complicated skin/soft tissue infxns; nosocomial pna
  • Possibly more ADEs than with Vanco e.g Red Man Syndrome; nephrotoxicity; G.I. upset; metallic taste
53
Q

Cell Wall/ Membrane Active Agents:

daptomycin, fosfomycin, bacitracin, cycloserine

A

Fosmomycin: PO for G+/- – used in UTIs in women as one time 3g dose (not as effective)

Bacitracin: highly nephrotoxic, ONLY USED TOPICALLY; surface lesions, irrigation of wounds/joints

Cycloserine: G+/- mianly for tx of resistant TB, last resort; serious ADEs: HA, tremors, acute psychosis

54
Q

Daptomycin

  • Route, dose
  • Spectrum
  • Use
  • ADEs
  • Monitor
A
  • IV; dose adjusted for renal fxn
  • Spectrum similar to Vanco but ALSO COVERS VRE, VRSA
  • Used for skin/soft tissue infections, bacteremia, endocarditis (last resort) –> inactivated by lung surfactant, NOT FOR PNA
  • Injxn site rxn; fever/chills; diarrhea, N/V
  • Monitor CPK d/t muscle cramps and weakness; d/c if muscle pain & elevation of CPK >5x UNL
55
Q

25 y.o female w/ 2-3day h/o worsening pain, redness, swelling of L leg following abrasion occuring during softball. Area is warm to touch, erythematous border. Over 24-36 hrs, leg increasingly painful, tight; mild LAD, fever/ chills, nausea

  • What are the sxs of infection?
  • What type of infection? What organisms are most commonly associated?
  • Recommend initial ABx tx
A
  • Inflammation, redness, pain, LAD, temperature/ chills, nausea
  • Cellulitis: S. aurus, S. pyogenes
  • PCNase-resistant PCN e.g. dicloxacillin
56
Q

2 days after starting her on dicloxacillin, pt develps maculopapular rash
-What alternative tx can be chosen?

A

1st generation IV cephalosporin e.g. Cefazolin (not used if anaphylactic against PCN)

57
Q

After 48 hrs of tx pt Cx/sensitivity reports are available:
Cx shows only Streptococcus sensitivity to PCN
-How would you change her therapy?
What if cx shows MRSA: how would you change therapy?

A
  • Keep her on Cefazolin because it will show sensitivity to that as well
  • Might have to switch to Vancomycin; CA-MRSA is also sensitive to Bactrim, Clindamycin (Antibiogram)
58
Q

Pt is started on Vanco 1500 mg IV q12h; 30 min after start of infusion, develops redness & flushing on her face/neck/back.

  • What type of rxn is pt experiencing?
  • How will you manage pt?
  • Assuming she stays on vanco & her condition improves, can she be sent home on PO Vanco tx?
A
  • Red Man Syndrome
  • Stop the infusion, wait til symptoms subside; halve the infusion rate!

-Yes!

59
Q

67 y.o man w/ DM c/o open ulcer on foot, fever/chills. 15 yr h/o poorly-controlled T2DM, 3 yr h/o recurrent foot ulcers. One ulcer on underside of foot is open/ inflamed w/ purulent fluid – no pain around area, unaware of worsening infection. Temp of 39.7C

  • Are all diabetic ulcers infected?
  • What sxs of infection does this pt have?
  • What type of infection does this pt most likely have?/ What organisms are MC associated with diabetic foot ulcers?
A
  • Not infected, but may be colonized
  • Open/inflamed ulcer; fever/chills; purulent fluid
  • Diabetic foot ulcer; Staph or Strep; G(-) like Klebsiella, Pseudomonas
60
Q
  • What initial ABx tx would you recommend for the pt with a diabetic foot ulcer?
  • After 48 hrs of therapy, C&S results show ESBL-producing Klebsiella. Would you change the ABx tx? If yes, provide alternative.
A
  • Extended-Spectrum PCN: e.g. Pipracillin w/ tazobactam to cover G+/- anaerobes d/t being on underside of foot; Augmentin if pt can tolerate PO; 4th gen Cephalosporin
  • Yes; Carbapenam (1st line for ESBL-producing bact)
61
Q

Tetracyclines

  • Examples
  • Spectrum of activity
  • Use
  • ADEs
  • Considerations
A
  • Tetracycline, minocycline, doxycycline
  • S. pneumoniae, S.pyogenes, CA-MRSA; E.coli, Klebsiella, H.flu; Chlamydia, Mycoplasma, Legionella, Borellia burgdorferi
  • Resp infections, CA-MRSA, acne; Doxy: anthrax, Chlamydia, Lyme
  • G.I intolerance, photosensitivity, tooth discoloration (NOT FOR 2ND HALF OF PREGNANCY or children < 8 y.o); Vestibular toxicity with minocycline – dizziness, ataxia, N/V –> d/c
  • Administer separate from food containing Al, Mg, Fe by at least 1-2 hrs (multivits); Tetracycline on empty stomach, Doxy w/ food d/t G.I intolerance, decreased absorption
  • Monitor renal, hepatic, CBC, hematologic labs w/ long-term use
62
Q

Tigecycline

  • Coverage
  • Use
A
  • Covers G+/- & anaerobes
  • Complicated skin/ structure infections, complicated abd infections; CAP; efficacy against MRSA, MRSE, VRE, PCN-resistant S. pneumoniae & other MDR organisms
  • SALVAGE THERAPY
63
Q

Macrolides

  • Examples
  • Special considerations
  • Coverage/use/ADEs for fidaxomicin
A
  • Erythromycin, clarithromycin, azithromycin, fidaxomicin
  • Azithromycin/ Erythromycin: 1 hr before or 2 hrs post-meal; otherwise no regard
  • Compliance lowered with erythromycin: q.i.d; azithromycin is QD; clarithromycin QD or b.i.d
  • DIs: erythro/clarithro are metabolized by CYP450, increase [drug]: warfarin!

Fidoaxomicin used for C.diff-associated diarrhea (not 1st line d/t cost); N/V, G.I hemorrhage, abd. pain

64
Q

Erythromycin/Clarithromycin/Azithromycin

  • Spectrum of Activity
  • Uses
  • ADEs
A
  • Strep; H.flu, Neisseria; Mycoplasma, Legionella, Chlamydia
  • Alternative for PCN allergy; CAP; OM
  • N/V (25% w/ erythromycin); abd pain; diarrhea
  • Renal failure
  • QT prolongation (erythromycin > clarithromycin > azithromycin) esp for pts on antiarrhythmics
  • CV risk with azithromycin esp in pts with high baseline risk of dz

Caution with azithromycin in pts with GFR <10 ml/min; dose adjust for Clarithromycin

65
Q

Clindamycin

  • Spectrum
  • Use
  • Considerations
A
  • Staph (MSSA, CA-MRSA); Strep; Clostridium (NOT difficile), Bacteroides
  • Usually added onto other, narrow-spec ABx; skin/soft tissue infxn (CA-MRSA – watch for resistance); anaerobic infxn, aspiration pna, alternative for dental prophylaxis in PCN allergy

-G.I. upset; skin rash; hepatotoxicity; back pain w/ vaginal
HIGHER INCIDENCE OF C.DIFF
-Admin w/ food to decrease upset; w/ full glass of water to decrease esophageal ulceration

66
Q

Linezolid

  • Spectrum
  • Uses
  • Considerations
A

-Staph (MSSA, MRSA, VISA, VRSA), Strep, Enterococcus (incl VRE)
-THE ONLY PO ABX WORKING AGAINST HA-MRSA OR VRSA (100% bioavailable)! Pts who aren’t elligible for at-home IV tx – used very sparingly
-Skin/soft tissue, bone/jt infxns; bacteremia; pna
-Reversible inhibition of MAO: caution w/ pts on SSRIs; avoid tyramine-containing foods
Thrombocytopenia MC in pts w/ renal failure, prolonged tx (reversible); peripheral/ optic neuropathy
Avoid unless necessarily in pregnant pts
-Preferable to Vanco in PVL-producing CA-MRSA

67
Q

Aminoglycosides
-Examples

  • Spectrum/use for gentamicin, tobramycin, amikacin
  • ADEs
A

-Gentamicin, Tobramycin (also inhaled for CF pts), Amikacin, Streptomycin (IV); Neomycin (topical unless bowel surgery prep (PO)), kanamycin (topical)

  • Staph, Strep, Enterococcus (some); Mostly aerobic G(-) bacilli coverage
  • Rarely used alone esp w/ Gram (+) organisms (synergistic w/ PCN, Vanco for endocarditis); UTI, pna, meningitis

-Ototoxic: vestibular (vertigo, ataxia) & auditory (tinnitus, hearing loss) – irreversible: monitor hearing acuity
Nephrotoxic: rise in SCr (increase in [trough] will be 1st sign)
Both usually only occur with >5 day duration, in elderly or in pts w/ impaired renals

68
Q 
Dosing aminoglycosides
-Variability
-Two dosing methods
Benefits of extended interval
-Monitoring
A
  • Dosing/ intervals are variable: depends on indication, renal function; wt based
  • Conventional (Q8h, Q12h) vs. Traditional/ extended interval dosing (Q24, Q36)
  • Extended interval: reduced nephrotoxicity, decreased monitoring (don’t measure peaks), no risk of sub-therapeutic level; decreased prep/admin time; easier for home care dose: most G(-), some G(+)

-Monitor renal fxn, serum [drug] every few days: trough & peak

69
Q

Sulfonamides

  • 2 MC
  • Spectrum
  • Uses
  • ADEs
A
  • Sulfisoxazole, Sulfamethoxazole/Trimethoprim = Bactrim
  • Staph, S. pneumoniae, anthrax, C. tetani; E.coli, Proteus, H.flu; C. trachomatis

-Comp/un-complicated UTIs (with pyrimethamine); Bactrim is 1st line against CA-MRSA, PCP tx & prevention
URIs

70
Q

Sulfonamides:

ADEs, Special Considerations

A
  • Photosensitivity; N/V/diarrhea; rash, STEVEN-JOHNSONS SYNDROME OR TEN: fever, flu-like symps, blistering/rash; blood dyscrasias
  • Sulfa allergies: use caution d/t cross-sensitivity

-Pt should drink plenty of fluids d/t crystallizations in kidneys
DIs with: Warfarin: may increae effects (INRs)
Methotrexate, phenytoin, digoxin

71
Q

Fluoroquinolones
-Examples

  • ADEs
  • Considerations
A
  • Ciprofloxacin
  • Levofloxacin
  • Moxifloxacin

-N/V/diarrhea/ constipation = MC
Tendonitis/tendon rupture: in elderly, renal insufficiency, concurrent steroid use
Hypoglycemia/ hyperglycemia
QT prolongation

-Reduced absorption with Mg, Ca, Al, Fe, Zn!! (separate by at least 2 hrs)
WARFARIN: MAY INCREASE INR: monitor
Avoid concomitant use w/ other meds that prolong QT intervals (antiarrythmics, TCAs): cipro least likely, moxi - most likely

72
Q

Ciprofloxacin, Ofloxacin, Norfloxacin

  • Spectrum
  • Uses
A

-Enterobacteria, H.flu, Neisseria; Pseudomonas (Cipro only), atypicals (Cipro, ofloxacin ony)
-Norfloxacin: uncomplicated UTIs
Cipro, ofloxacin: complicated UTIs, STDs, skin infections

73
Q

Levofloxacin, Moxi, Gatifloxacin

A
  • Strep (incl PRSP); Enterobacteria, H.flu, M. catarrhalis, Neisseria, Pseudomonas (Levo only)
  • Similar indications as 2nd gen Cephalosporins + CA-PNA & URIs

Moxi not used for UTIs (only one that doesn’t need renal adjust)

74
Q

Metronidazole

  • Spectrum
  • Uses
  • ADEs
  • Admin
  • DIs
A
  • PROTOZOA & ANAEROBES: Bacteroides, C.diff, etc.
  • Intra-abdominal, gynecologic infxns; colitis caused by C.diff, eradication of H.pylori (in combo)

-G.I: N/V, xerostomia, metallic taste, anorexia, abd pain
CNS: peripheral neuropathy, seizures –> d/c!

-Extended-release tablets: admin on empty stomach (1 hr before meal)

-Avoid alcohol during & 3 days after admin!
May increase INR w/ warfarin

75
Q

Nitrofurantoin

  • Spectrum
  • Uses
  • Considerations
  • ADEs
  • DIs
A
  • Staph, Strep, Enterococcus; E.coli, Klebsiella
  • Uncomplicated UTIs (young women)
  • DO NOT USE IN CRCL < 60ML/MIN (elderly women)
  • Admin w/ food/milk to increase GI tolerance
  • ADEs: GI, serious with long-term tx: hepatotoxicity, pulmonary toxicity –avoid in elderly
  • DIs: Probenecid increases [serum]

-More effective against E.coli vs. Bactrim

76
Q

A 38 y.o W comes to see you for a UTI. She tells you that she had a Rx for moxifloxacin for her last UTI and it “worked great.” Assuming no Contraindications to tx, do you agree or disagree with this tx?

A

NO. This tx is not approved for UTIs: doesn’t attain [therapeutic] in the urine

Cipro & levofloxacin are appropriate alternatives

77
Q

Empiric ABx tx for Cystitis

-Uncomplicated vs. Complicated

A

Uncomplicated

  • Bactrim 1 tablet b.i.d x3 days
  • Nitrofurantoin 100 mg PO b.i.d. x 5 days
  • Fluoroquinolone (Levo or Cipro)

Complicated

  • Bactrim same x 7-14 days
  • Fluoroquinolone (Levo or Cipro w/ doubled dose)
78
Q

68 y.o M c/o cough, sputum production, SOB. You suspect CAP. He tells you that he currently takes lisinopril bc “his kidneys were starting to not work as well.” He also takes warfarin for his afib.
Is Azithromycin an appropriate tx option for this pt?

A

Yes but this pt needs close monitoring d/t potential for DI with warfarin; consider kidney failure and CV effects

Possible to add a B-lactam d/t renal dysfunction comorbidity

79
Q

Treating CAP

  • For previously healthy/ not on ABx for prev 3 mo
  • With co-morbidities, immunosuppression or ABx w/in 3 mo
  • Areas of high macrolide resistant-S.pneumoniae
A

-Macrolides: Azithromycin, Clarithromcyin;
Doxy

  • B-lactam (high dose amoxicillin or Augmentin; alternatives: ceftriaxone, cefuroxime) + a macrolide OR respiratory fluoroquinolone (levofloxacin or moxifloxacin)
  • B-lactam + macrolide OR respiratory fluoroquinolone
80
Q

JT is a 59 y.o W who presents w/ a bright red rash on her nose. The wound is dry and edematous. Is Keflex (cephalexin) an appropriate agent to treat this?

A

Yes. Given the presentation (erysipela) it is likely Strep. This 1st gen cephalosporin will treat mild skin infections

PCN would also be appropriate

81
Q

Treatment of cellulitis

  • Mild- moderate
  • If CA-MRSA suspected
  • If S. pyogenes suspected
  • Duration
A
  • Dicloxacillin PO, cephalexin PO, Clindamycin PO
  • Bactrim PO, Doxy PO, Clindamycin PO
  • PCN 500 mg PO q.i.d for Strep pyogenes
  • 5-10 days duration
82
Q

TRUE/FALSE: Pts who are allergic to PCNs are though to have a 15% chance of also being allergic to cephalosporins

A

False; more-so a PCN contamination issue, more like 3-7% cross-sensitivity

83
Q

Which of the following fluoroquinolones does NOT required dosage adjustments for renal insufficiency?

A. Moxifloxacin
B. Levofloxacin
C. Cipro
D. Norfloxacin

A

A. Moxifloxacin

84
Q

A 22 y.o W presents w/ a prescription for Levaquin (Levofloxacin) for her skin infection which you see has purulent d/c. 3 other lacrosse team members have this infection, she wants advice on how to prevent this in the future.

Given her story, do you think Levaquin is the best option? How can she prevent this in the future?

A

NOT the best option here; most infections are caused by Staph for which Levofloxacin DOES NOT provide reliable coverage

Cephalexin or dicloxacillin would be appropriate

Prevention: don’t share equipment, don’t shave legs right before practice, thorough hygiene afterwards

Miscellaneous (6 decks)

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