Exam 1: Antimicrobials and Antibiotics Flashcards
Class of antibiotic to use in immunocompromised patients:
Bactericidal
Reason for preserving normal/GI flora if possible:
Normal flora have antixenobiological action
Type of abx usually used in OR:
Cheap, broad spectrum
Are abx always necessary in OR?
No; pts with allergies and superficial surgeries may not need
SCIP guidelines for abx:
Single dose within 1 hr of incision
Considerations for selection of abx:
ID of causative organism
Drug delivery to site
Single drug if possible
Route, duration, cost
Pts who particularly need prophylactic abx:
Bowel/appy
Hardware
Diabetics
Extended surgical time
Relationship between hypersensitivity reaction and dose:
Independent
Relationship between drug toxicity and dose:
Dose related
Abx concerns with parturients:
Most abx cross the placenta and enter milk
Possible teratogenicity
Abx concerns with elderly:
Renal impairment
Decreased plasma protein
Reduced GI mobility, acidity
Increased body fat = more drug in tissues
Penicillin structure and mechanism of action:
Bactericidal beta-lactam
Interferes with bacterial cell wall
Organisms susceptible to penicillin:
-coccals
Pneumococcal
Meningococcal
Streptococcal
Penicillin elimination:
Renal
Ampicillin organisms:
Gram(-)
H. influenza, e. coli
Notable ampicillin adverse effect:
Skin rash
Amoxicillin advantage over ampicillin:
More efficiently absorbed from GI tract
Most allergenic antimicrobial:
Penicillins
Most common adverse reaction to PCNs:
Allergy/hypersensitivity
Signs of PCN allergy:
Rash and/or fever
Anaphylaxis
Hemolytic anemia
Classes of abx with cross-sensitivity and % chance:
PCNs and cephalosporins
8% chance
Cephalosporin mechanism of action:
Bactericidal
Inhibits bacterial cell wall synthesis
Cephalosporin elimination route:
40% bile
60% renal
Cephalosporin organisms:
Broad spectrum
Primary s/s of cephalosporin allergy:
Rash
% incidence of anaphylactic rxn to cephalosporin:
0.02%
First, second, and third generation cephalosporins:
1st: cefazolin
2nd: cefoxitin
3rd: cefotaxime
Type of surgery that often uses cephalosporins and why:
Ortho - cephalosporins penetrate into joints
Differences in cephalosporin generations:
Better anti-Gm(-) activity in later generations
Aminoglycoside mechanism of action:
Bactericidal
Inhibits cellular activity inside microbe
Aminoglycoside organisms:
Aerobic Gm(-)
Aminoglycoside elimination & elimination half-time
Extensively renal
2-3hr elimination half-time in healthy pt
20-40x increase in renal failure
Aminoglycoside adverse effects:
Ototoxicity
Nephrotoxicity
Skeletal muscle weakness
Prolongs NMB
Mechanism of aminoglycoside ototoxicity:
Irreversible damage to vestibular/cochlear hairs
Dose dependent
Mechanism of aminoglycoside nephrotoxicity:
Accumulation in renal cortex –> tubular necrosis –> proteinuria, dilute urine, RBC casts
Reversible!
Most nephrotoxic aminoglycoside:
Neomycin (mostly given topical for this reason)
Mechanism of aminoglycoside muscle weakness:
Inhibits pre-synaptic ACh release
Decreases post-synaptic sensitivity to ACh
Patient population in whom aminoglycosides should be avoided:
Myasthenia gravis
“Sneaky” way aminoglycosides become systemically absorbed:
From irrigation fluid
Drug effect enhanced by aminoglycosides:
NM blocking properties of lidocaine
Five aminoglycosides:
Streptomycin Kanamycin Gentamicin Amikacin Neomycin
Toxic level of gentamicin:
> 9mcg/ml
Unique use of neomycin:
Adjunct therapy to hepatic coma
Aminoglycosides with limited use due to ototoxicity:
Streptomycin/kanamycin
Tetracyclines mechanism of action:
Bacteriostatic
Inhibits bacterial protein synthesis
Common use of tetracyclines:
Treatment of acne via decrease in fatty acid content of sebum
Tetracyclines elimination:
Excreted in urine and bile
Tetracyclines side effects:
Discoloration of teeth (in developing fetus/children)
Photosensitivity
Hepatic/renal damage in high doses
Administration of tetracycline:
PO only
Administration of doxycycline:
IV or PO
Macrolide drugs:
Erythromycin, azithromycin
Erythromycin mechanism of action:
Can be bacteriostatic or bactericidal
Inhibits bacterial protein synthesis
Erythromycin organisms:
Gm+ bacteria
Narrow spectrum
Erythromycin elimination:
CYP450 metabolism
Excreted mostly in bile
Erythromycin adverse effects:
GI (esp. IV)
QT effects
Thrombophlebitis (prolonged IV use)
Physiologic alteration that increases erythromycin side effects:
CYP450 inhibition
Clindamycin class:
Linomycins
Clindamycin mechanism of action:
Bacteriostatic
Inhibits bacterial protein synthesis
Clindamycin organisms:
Anaerobes
Clindamycin uses:
Serious GI or female genital tract infections
Clindamycin dosing considerations:
Decrease dose with severe liver disease
Clindamycin adverse effects:
Pseudomembranous colitis
Pre- and post-synaptic effects at NMJ - unantagonizable with calcium or anticholinesterases
Vancomycin class:
Glycopeptide derivative
Vancomycin mechanism of action:
Bactericidal
Impairs cell wall synthesis
Vancomycin organisms:
Gm(+) bacteria
Staph
Strepto- and enterococcus
MRSA
Vancomycin elimination & elimination half-time:
Renal excretion
6 hrs
Up to 9 days in renal patients
Vancomycin surgical uses:
Cardiac procedures
Ortho procedures with prosthetics
CSF, shunt infections
Vancomycin dosing & concentration:
10-15 mg/kg over 60 min
1gm/250ml concentration
Vancomycin adverse effects:
Profound hypotension with rapid infusion
Red man syndrome
Ototoxicity/nephrotoxicity
Mechanism of red man syndrome:
Facial/truncal erythema from histamine release
Sulfonamides mechanism of action:
Bacteriostatic
Inhibit bacterial folic acid synthesis
Sulfonamide uses:
UTIs
Sulfonamide elimination:
Hepatic metabolism
Renal excretion
Sulfonamide side effects:
Skin rash, anaphylaxis Drug fever Hepatotoxicity Acute hemolytic anemia Increase PO anticoagulant effect
Polymixin B/colistimethate mechanism of action:
Bactericidal
Affects bacterial cell wall phospholipids
Polymixin B/colistimethate organisms:
Gm(-) bacteria
Polymixin B/colistimethate uses:
Severe UTIs
Skin, mucous membrane, eye, ear infections
GI tract sterilization (poop transplant)
Polymixin B/colistimethate elimination:
Renal elimination
Polymixin B/colistimethate side effects:
Most potent at NMJ
Very nephrotoxic
Metronidazole mechanism of action:
Bactericidal
Metronidazole organisms:
Anaerobic Gm(-) bacteria
Metronidazole uses:
CNS infections
Abdominal/pelvic sepsis
Pseudomembranous colitis
Fluoroquinolones mechanism of action:
Bactericidal
Fluoroquinolones organisms:
Enteric Gm(-) bacilli
Fluoroquinolones elimination & elimination half-time:
Mostly renal excretion
3-8 hr half-time
Fluoroquinolones drug example:
Ciprofloxacin
Fluoroquinolones adverse effects:
CYP450 inhibition GI disturbances (mild)
Fluoroquinolones uses:
Systemic infections, bone, soft tissue, respiratory tract, GI, GU
Rifampin mechanism of action:
Bactericidal
Inhibits RNA chain in microbe
Rifampin organisms:
Mycobacteria - tuberculosis
Gm(+) - most
Gm(-) - many
Rifampin administration and excretion:
Oral or parenteral
Bile and urine excretion
Penetrates into CNS
Rifampin side effects:
CYP450 induction Thrombocytopenia Anemia Hepatitis Fatigue/weakness Numbness
Amphotericin B use:
Yeasts and fungi
Amphotericin B administration:
IV only
Amphotericin B elimination:
Renal - slowly!
Amphotericin B adverse effects
Renal function impairment (80%!!) Fever, chills, dyspnea, hypotension Hepatic impairment Hypokalemia Allergies Seizures Anemia/thrombocytopenia
Classification of viruses:
DNA or RNA
Acyclivir & valacyclovir use and elimination:
For the herps
Renal excretion
Vidarabine uses and side effects:
Cytomegalic inclusion disease
HSV encephalitis
Mutagenic, carcinogenic
Famciclovir use:
Acute herpes zoster
Ganciclovir use and adverse effect:
CMV disease
Hematologic toxicity
Amantadine use and elimination:
Influenza A virus and Parkinson’s
Renal excretion
Interferons mechanism of action:
Induce enzymes that inhibit viral replication
Enhance anti-tumor activities of macrophages
Interferons uses:
Hepatitis B (chronic)
Hepatitis C
Nasal sprays
Interferons side effects:
Flulike symptoms Hematologic toxicity Depression, irritability, decreased concentration Autoimmune conditions Rash, alopecia CV, thyroid, hepatic changes
Types of AIDS antivirals:
Nucelotide reverse transcriptase inhibitors
NON-nucleotide reverse transcriptase inhibitors
Protease inhibitors
AIDS antiviral side effects:
Pancreatitis, hepatitis, lactic acidosis, fat changes, increased cholesterol/trigs, hypersensitivity
Protease inhibitors are potent CYP450 inhibitors