Antimicrobials Flashcards
SCIP 1
Prophylactic abx received within 1 hr prior to surgical incision
SCIP 2
Prophylactic antibiotic selection for surgical patients - choose abx appropriate for patient and surgery
SCIP 3
discontinue prophylactic abx within 24 hours after surgery (48 hours for cardiac patient)
SCIP 4
cardiac surgery patient w/ controlled 6am post-op glucose (<200)
SCIP 5
post-op wound infection diagnosed during index hospitalization
SCIP 6
surgical patients with appropriate hair removal
SCIP 7
colorectal patients with immediate postoperative normothermia
hypothermia results in:
peripheral vasoconstriction, decreased wound oxygen tension and recruitment of leukocytes, favoring infection and impaired healing
How are PCN classified into subgroups?
B-lactamase susceptibility, structure, and spectrum of activity
Penicillins interfere with synthesis of _______
peptidoglycan
What is peptidoglycan?
essential component of cell walls in bacterias
Penicillins decrease the availability of an ______ of murien hydrolase
inhibitor
When murien hydrolase is uninhibited, it:
destroys (lyses) the structural integrity of bacterial cell walls
What do resistant gram-negative bacteria have/do that prevents PCN from working?
cell membranes that prevent the penicillin from getting to the site of peptidoglycan synthesis; the bacteria could produce B-lactamase enzymes that hydrolyze the B-lactam ring and make the penicillin inactive
T/F: Penicillin is ONLY active against growing bacteria
TRUE
High doses of PCN G may result in _____ and ______
Hyperkalemia and neurotoxicity
PCN G has ____ meq of K per 10 million U
16
PCN G is _____% ______ excreted
90% renally
3 drugs that prolong PCN duration of action
probenecid
procaine
benzathine
Penicillinase-Resistant PCN (list names of drugs)
Methicillin Nafcillin (80% bile excreted) Oxacillin (hepatitis SE) Cloxacillin (PO) Dicloxacillin (PO)
Penicillinase-resistant PCN are used to treat what infections?
Staphylococci
What makes penicillinase-resistant penicillins resistant?
not susceptible to hydrolysis of B-lactam ring by bacteria
What generation are Penicillinase-susceptible broad spectrum penicillins?
2nd generation
Penicillinase-susceptible broad spectrum penicillins (list drugs)
Ampicillin
Amoxicillin
Does staphylococcus respond to Penicillinase-susceptible broad spectrum penicillins (2nd generation PCN)?
No
Of penicillins, which has highest incidence skin rash?
Ampicillin
Ampicillin has (broader/narrower) activity then PCN G
broader
Amoxicillin or Ampicillin: which is better absorbed from GI tract?
Amoxicillin
Amoxicillin or Ampicillin: which has longer effective circulating concentrations?
Amoxicillin
Which generation are Extended-Spectrum Carboxypenicillins?
third generation
Extended-Spectrum Carboxypenicillins (list the drugs)
Carbenicillin
Is Carbenicillin effective against staph aureus?
No
Side effects of Carbenicillin:
CHF (>10% drug is Na)
hypokalemia
metabolic alkalosis
increased bleeding time with normal platelet count
What generation are extended-spectrum acylaminopenicillins?
4th generation
Are extended-spectrum acylaminopenicillins effective against staph aureus?
No
Extended-spectrum acylaminopenicillins (list drugs)
Mezlocillin
piperacillin
azlocillin
Which subgroup has broadest spectrum of all penicillins?
extended-spectrum acylaminopenicillins
Is piperacillin effective against staph aureus and penicillinase-producing bacteria?
No
Penicillinase B-lactamase Inhibitors MOA:
B-lactam compounds have little intrinsic antimicrobial activity. They bind irreversibly to B-lactamase enzyme so drugs that were inactivated by this enzyme (and breaking of the B-lactam ring) are no longer susceptible, and can work against these bacteria
Penicillinase B-lactamase Inhibitors (list them)
Clavulanic acid
Sulbactam
Tazobactam
Penicillinase B-lactamase Inhibitors Combinations (list the pairings)
Clavulanic acid + amoxicillin
Sulbactam + ampicillin
Tazobactam + piperacillin
Why do we use cephalosporins?
wide therapeutic index
cost effective
low incidence of side effects
What surgery are cephalosporins used in?
GI/GU surgery
Incidence of allergic reactions in cephalosporins
1-10%
Side effects cephalosporins:
\+ Coombs reaction (antibodies react against RBCs) hemolysis nephrotoxicity bronchospasm urticaria hemodynamic collapse
Life threatening anaphylaxis in cephalosporins:
0.02%
Most common adverse reaction to B-lactam antimicrobials:
hypersensitivity (IgE antibodies)
Most allergenic of all drugs:
Penicillin, 1-10%
95% of patients allergic to PCN for ____ metabolite
penicilloyl-protein conjugate (major antigenic determinant)
minor antigenic determinant is 6-aminopenicillicacid + benzylpenamaldic
T/F: 1st gen cephalosporins are just as good as 2nd and 3rd gen against staphylococci and nonenteral streptococci
True
allergy to one penicillin increases likelihood of allergy to other penicillins because of ____, which also is a potential for cross reactivity between PCN and cephalosporins
a common nucleus (B-lactam ring)
Actual cross reactivity between cephalosporins and PCN
textbook says rare, in class she said 1-3%
First generation cephalosporins (list them)
Cephalothin
Cephazolin
How are cephalosporins eliminated?
kidneys
Drug of choice for antimicrobial prophylaxis for many surgeries
Cephazolin
Second generation cephalosporins (list them)
Cefoxitin
Cefamandole
Cefuroxime
Which is the only second generation cephalosporin effective in treating meningitis?
Cefuroxime
Generally, activity against gram ___ cocci decreases and activity against gram ____ cocci increases from the first to the third generation
positive; negative
Third generation cephalosporin is different from the others… how?
enhanced ability to resist hydrolysis by the B-lactamases of many gram negative bacilli and can achieve therapeutic levels in CSF (so used against meningitis)
Third generation cephalosporins (list them)
Cefotaxime
Ceftriaxone
Cefixime
Do you reduce the cephalosporins dose or frequency in ESRD?
yes
first generation: decrease dose
second generation: do not give ESRD
third generation: cleared renal and hepatic, still reduce dose in renal patient
Aztreonam effective against gram ____ bacteria only
negative
Does Aztreonam have B-lactam ring?
Yes
Is Aztreonam cross sensitive with PCN/cephalosporins?
No
Side effect Aztreonam:
enterococcal superinfection
Aminoglycosides are excreted:
renally
Aminoglycoside lipid solubility:
poor. less than 1% oral administration is absorbed systemically
Aminoglycoside normal half-life 2-3 hours in normal renal function.
half-life in renal failure:
20-40x normal
Side effects aminoglycosides:
ototoxicity (vestibular and auditory)
nephrotoxicity
skeletal muscle weakness (potentiates NMB, do not give in MG)
Aminoglycosides (list them)
gentamicin
streptomycin
amikacin
neomycin
Gentamicin is active against:
P. aeruginosa and gram negative bacilli
Important to _____ when administering gentamicin
monitor plasma concentration
What is toxic level of gentamicin?
> 9 ug/ml
Macrolides are absorbed (well/poorly) from GI tract
well
Macrolides (list them)
Erythromycin
Azithromycin
Clindamycin
Vancomycin
Do you need to alter erythromycin dose in renal failure?
No, excreted in bile
Part of new combo treatment for COVID-19
Azithromycin
Clindamycin is used for infection of:
GI tract and female genital tract
Clindamycin is excreted:
hepatic ally, decrease dose in liver patients
Side effects of clindamycin:
pseudomembranous colitis (swelling or inflammation of large intestine due to c. diff)
diarrhea
large dose can induce NMB in absence of non depolarizer
skin rash
Clindamycin has (more/less) activity against anaerobes (usually gram negative) than erythromycin
More
MRSA drug of choice
Vancomycin
Is routine prophylaxis with vancomycin recommended?
No, because concerns of resistant organisms
Vancomycin works against gram ____ bacteria
positive (impairs cell wall synthesis)
Is vancomycin absorbed in GI tract?
no, poorly absorbed in GI tract
Vancomycin should be infused over ____ minutes to minimize ______
60 minutes; occurrence of drug-induced histamine release and hypotension
Vancomycin should be started ____ hour(s) before surgery for prophylaxis
2 (per stoelting)
Vancomycin is excreted by _____
kidney
Does vancomycin dose have to be adjusted in renal failure?
yes
Important guide to dosing vancomycin (especially in renal failure):
plasma vancomycin levels
Side effects vancomycin administration:
Red Man Syndrome arterial hypoxemia, low SpO2 ototoxicity nephrotoxicity (with aminoglycoside) Vanco + succs = NMB histamine release bronchospasm
Red man syndrome
rate dependent infusion reaction- NOT A TRUE ALLERGIC RXN
intense facial and truncal erythema
rapid infusion (<30 min) can cause hypotension and cardiac arrest
pruritus
myalgia, dyspnea
venodilation, decreased ventricular filling
Treatment of pseudomembranous colitis
Metronidazole
Which abx causes pseudomembranous colitis?
Clindamycin
Fluoroquinolones (list them)
Ciprofloxacin (M. tuberculosis)
Moxifloxacin (serious SE, last resort)
Vancomycin dose
10-15 mg/kg over 60 min
prophylaxis:
<90 kg 1 gm
90-120 kg 1.5 gm
>120 kg 2 gm
Silver nitrate is used as a:
caustic, antiseptic, astringent
Silver nitrate is strong bactericidal, especially for
gonococci
Silver nitrate is used in prophylaxis for
ophthalmia neonatorum
Silver nitrate SE
hypochloremia
hyponatremia
methemoglobinemia
Chlorhexidine MOA
disrupts cell membranes of the bacterial cells
Chlorhexidine is effective against gram ____
positive and negative
Chlorhexidine is ____ effective in decreasing number of normal cutaneous bacteria than povidone-iodine and hexachlorophene
more- greater initial decrease
Chlorhexidine is used for
preoperative reduction of cutaneous flora for the surgeon and patient
Chlorhexidine solution in alcohol base can cause:
deafness and corneal injury (if instilled in middle ear or eye)
Chlorhexidine potential for contact sensitivity and photosensitivity is:
Low