Random Info Flashcards
Murein Hydrolase
Bacterial autolytic enzyme activated for autolysis and bactericidal effect of penicillin
Transpeptidase
Bacterial enzyme (and PBP) located on the outside of the cell membrane, catalyzes the final cross-linking of peptidoglycans in cell wall formation
Which bacteria lacks high permeability porins?
P. aeruginosa
Which bacteria has active efflux?
P. aeruginosa, N. gonorrhoeae, E. coli
Which bacteria produces large amounts of beta-lactamases when induced, which are secreted outside the bacteria?
S. aureus
Major antigenic determinant in penicillin hypersensitivity rxn
Benzylpenicilloyl
Serum Sickness is an example of a Type ____ HSN
III
Vasculitis is an example of a Type ____ HSN
III
Penicillins that are highly bound to plasma proteins
Nafcillin, Oxacillin, Dicloxacillin
Penicillins that are moderately bound to plasma proteins
Penicillin G, Penicillin V, Carbenicillin, Ticarcillin, Methacillin, Ampicillin, Amoxicillin
Structure of Penicillin includes
Thiazolidine ring, B-lactam ring, R goup
Highly Penicilin-resistant S. pneumo has
4/5 PBPs w decreased affinity
MRSA is caused by acquisition of
high MW PBP via a transposon
G(+) bacteria produce large amts of B-lactamase and secrete them
outside the bacterial cell
G(-) bacteria produce B-lactamase and secrete them
b/w the inner & outer membrane
Why are G(-) bacteria more resistant to Penicillin?
Outer membrane protects the peptidoglycan layer, secrete B-lactamases in the periplasma space protecting the transpeptidases
What is the only penicillin thats absorption is not effected by food
Amoxicillin
Which penicillin is 98% bound to plasma protein
Dicloxacillin
Which penicillin is secreted by biliary excretion?
Nafcillin
Which penicillin is secreted by biliary & kidney excretion?
Oxacillin & Dicloxacillin
How could one have penicillin Abs w/o ever taking penicillin?
exposure through breast milk or cows milk or other food products
Risk Factors for penicillin HSN rxns?
Adult > Children, Topical > IV > Oral, long-term use/high dose Tx
Type I HSN rxns involve
IgE production, binding of IgE to mast cells & basophils, antigen causes cross-linking of IgE Fc on mast cells (activation), release of histamine & vasoactive mediators -> vasodilation & vascular permeability & SM relaxation at periphery, SM constriction of bronchus/GI
IL-4
Drives Th0 -> Th2 immune response
Hyposensitizing Method to avoid Type I HSN
production of IgG blocking Abs that remove antigen before it binds IgE, switch from Th2 to Th1
Desensitization Method to avoid Type I HSN
Begin w/ small doses & increase over hours, this slowly induces mast cell degranulation to avoid a lethal rxn
Contact dermatitis is an example of a Type ___ HSN rxn
IV
interstitial nephritis is an example of a Type ___ HSN rxn
IV
Drug fever is an example of a Type ___ HSN rxn
IV
Type II HSN rxn involves
Immune complexes (Ag-IgG), IC deposition, C5a & C3a production -> vascular permeability, neutrophils attempt to phagocytize ICs & release inflammatory substances -> retarded BF, thrombi, rupture of vessel wall, hemorrhage, necrosis
Hemolytic anemia is an example of a Type ___ HSN rxn
II
Which penicillin is the most common cause of acute allergic interstitial nephritis & is no longer on the market?
Methicillin
Skin testing can detect Type ____ HSN
Type I
Pre-Pen
Skin testing; analogue of the major antigenic determinant (Benzylpenicilloyl)
Which penicillins may cause non-allergic rashes?
Ampicillin & Amoxicillin
Which penicillin’s absorption is least affected by food?
Amoxicillin
Ampicillin & Amoxicillin have an extended spectrum of coverage that includes
HELPSS ME: H. influenzae, E. coli, Listeria, Proteus, Salmonella, Strep (pyogenes & pneumo), Moraxella, Enterococcus
Why do Ampicillin & Amoxicillin have an extended spectrum of coverage
better penetration into the G(-) Outer Membrane
Which penicillins cause decreased efficacy to oral contraceptive?
Ampicillin & Amoxicillin
Broadest spectrum penicillin?
Imipenem
AOM - most likely agents
strep pneumo, hib, moraxella catarrhalis
Which bacteria may alter its porin channels or actively efflux penicillin?
P. aeruginosa
if creatinine clearance is <10 mL/min give dose adjust penicillin by administering
1/4 to 1/3 of normal dose
Which drugs would you need to adjust dosage for in liver failure pts?
Nafcillin & Oxacillin
If pt has renal impairment & the dose is not adjusted, what outcomes may result?
Seizures (CNS toxicity)
If pt requires Penicillin (as in Syphilis) how can we provide them Tx?
Desensitize (low dose, increase every 15-20m)
During a desensitization protocol make sure to have wha on hand?
Epinephrine in case of a severe Type I Rxn
AOM caused by S. pneumo may acquire resistance d/t
altered PBPs - low affinity
AOM caused by HiNT may acquire resistance d/t
B-lactamase production
AOM caused by M. catarrhalis may acquire resistance d/t
B-lactamase production
How would you Tx AOM caused by S. pneumo w/ acquired resistance
Increase dose + B-lactamase inhibitor
AOM Tx if pt is allergic to Penicillin?
2nd gen cephalosporin (Cefuroxime axetil, Cefprozil)
or 3rd Gen (Ceftriaxone)
Which drug interferes w/ the secretion of penicillin?
Probenacid (Gout Tx)
Bacterial meningitis in a young child is found to be Listeria, what penicillin could you use to Tx them?
Ampicillin
Salmonella infections should be Tx w/
Fluoroquinolones - Ciprofloxacin
Prophylaxis for surgery to prevent infection w/ S. aureus
Cefazolin
B. fragilis coverage
Cefoxitin
Empirical therapy for sepsis in immunocompetent or immunocompromised pt
3rd Gen Cephalosporin
Only cephalosporin excreted in bile
Ceftriaxone
Neurological complications d/t Lymes
Ceftriaxone
Gonorrhea Tx
Ceftriaxone or Cefixime
May cause bleeding disorders
Cefazolin
EtOH Intolerance
Cefazolin
cephalosporin w/ P. aeruginosa coverage
Cefepime, Ceftazidime
