Antimicrobials Flashcards
What are the goals of administering antimicrobials?
- to inhibit growth of microorganisms but not hurting the host
- give as narrow a spectrum as possible so that the normal flora can be maintained.
- consider if the pt is seriously ill or immunocompromised
- these patients will need bacteriocidal antibiotics
what are some types of adverse reactions that can be had with antimicrobials?
- hypersensitivity reaction (dose dependent)
- direct organ toxicity (dose related)
- potential for superinfections
- cross-reactions with other medications we give
What is an SSI? How is it defined?
- An infection related to an operative procedure that occurs at or near the surgical incision within 30 days of the procedure
- purulent exudate from surgical site
- a positive culture obtained from a surgical site that was closed initially
- A surgeon’s diagnosis
- A surgical site that requires reopening due to at least one of the following:
- tenderness, swelling, redness, or heat
What specific aspects of a surgery can increase the risk of infection?
What surgeries have the highest incidence of infection?
- procedure type
- skill of surgeon
- use of foreign meterial or implantable device
- degree of tissue trauma
- highest incidence: Carotid endarterectomy, urologic, colon
What patient traits increase the risk of surgical site infection?
- DM
- smoking
- obesity
- malnutrition
- systemic steroid use
- immunosuppressive therapy
- intraoperative hypothermia
- trauma
- prosthetic heart valves
What adverse outcomes are associated with hypothermia?
- increased blood loss
- increased transfusion requirements
- prolonged PACU stay
- post-op pain
- impaired immune function
- compromised neutrophil function causing vasoconstriction and tissue hypoxia; increasing incidence of SSI
What are the appropriate antibiotics for Cardiothoracic and vascular surgery?
What if the pt has a b-lactam allergy?
- Cefazolin, cefuroxime, or vancomycin
- b-lactam allergy: vancomycin or clindamycin
What is the difference between bacteriocidal and bacteriostatic?
- Bacteriocidal: kills the susceptible bacteria
- Bacteriostatic: reversibly inhibits the growth of bacteria
- for bacteriostatic, the duration of the therapy must be long enough to allow the person’s defense mechanisms to eradicate the bacteria
What are some bacteriocidal antibiotics?
- PCNs and cephalosporins
- Isoniazid
- metronidazole
- polymyxins
- rifampin
- bacitracin
- aminoglycosides
- vancomycin
- quinolones
- PIMP-R-BAVQ (this mneumonic has been censored due to adult content)
What are some bacteriostatic antibiotics?
- Chloramphenicol
- clindamycin
- macrolides
- sulfonamides
- tetracyclines
- trimethoprim
- Cora carries more sulfur than Tim
from the list of ABX she elaborated on during lecture, “the list is SLiM”: (by default the rest she talked about are bacteriocidal)
- Sulfa
- cLindamycin
- Macrolides
What is the structure of Penicillin?
-
- dicyclic nucleus that has a thiazolidine ring connected to a B-lactam ring
Is Penicillin bacteriocidal or bacteriostatic?
MOA?
What kind of organisms can affect?
- interferes with the synthesis of peptidoglycan which is an essential component to cell walls of susceptible bacteria
- Organisms:
- pneumococcal
- meningococcal
- streptococcal
- actinomycosis
How is Penicillin excreted?
What can increase the E 1/2t?
- Rapid renal excretion; plasma concentration decreases 50% in 1st hour
- 10% is excreted through glomerular filtration
- 90% secreted by renal tube
- anuria increases elimination half time by 10x
Penicillin adverse reactions
- Most allergenic antimicrobial (up to 10%)
- rash, with or without fever
- hemolytic anemia
- maculopapular rash (delayed)
- immediate sensitivity: anaphylaxis
- cross-sensitivity common with all PCN drugs AND cephalosporins
Why is there cross sensitivity between PCN and cephalosporins?
How common is it?
Because both classes have a b-lactam ring
anywhwere from 2-8% of people with PCN allergy are also allergic to cephalosporins
What is the difference between 1st and 2nd generation PCNs?
Examples?
- The later generations are also efective on some gram- bacilli
- haemophilus influenza
- E coli
- Examples: Amoxicillan, ampicillin
If your patient is allergic to 1st generation PCN, can you give them a 2nd?
No! You should substitue it with clindamycin or vancomycin
Are cephalosporins (Cefazolin) -cidal or -static?
MOA?
- Bactericidal- inhibits bacterial cell wall synthesis and have low toxicity
Facts about Cefazolin:
spectrum of activity?
allergy incidence?
excretion?
- Broad spectrum activity
- allergy incidence is 1-10%
- anaphylaxis is 0.02%,
- PCN and cephalosporin allergy 1-3%
- Renal excretion
Which generation of cephalosporin is best for Menningitis?
- 3rd generation
- achieves therapeutic levels in the CSF and they also have lower toxicity than earlier generations
What is the structure of Macrolides?
two examples?
Which is the prototype?
- macrolytic lactone ring containing 14-16 atoms with a deoxy sugar attached
- Erythromycin, Azithromycin
- Prototype: erythromycin
Is Erythromycin -cidal or -static?
MOA?
What kinds of bacteria is it effective against?
- It can be either, depending on the type of organism they are treating
- MOA: inhibits bacterial protein synthesis
- Effective against:
- Gram + bacilli
- pneumococci
- streptococci
- staphylococci
- mycoplasma
- chlamydia
How is Erythromycin metabolized?
How might this effect other meds?
- metabolized by the CYP450 and excreted in bile
- ay increase serum concentration of theophylline, warfarin, cyclosporine, methylprednisone, and digoxin
- no need to alter dose in renal patients
What are the side effects of Erythromycin?
- GI intolerance
- promotes gastric emptying- causes cramping
- N/V
- Cholestasic hepatitis
- decreased bile secretion from hepatocytes or decreased flow of bile through ducts
- QT effects
- prolongs cardiac repolarization
- torsades de pointes
- thrombophlebitis
- common with prolonged IV use
Clindamycin
class?
-cidal or -static?
Effective against what kinds of bacteria?
- Class: Linomycins
- Bacteriostatic
- Effective against: (similar to Erythromycin)
- gram + bacilli
- pneumococci
- streptococci
- staphylococci
- mycoplasma
- chlamydia
- **more effective against anaerobes
Why is Clindamycin’s use limited to infections that are difficult to treat?
What surgeries is it most commonly used for?
- Severe GI complications
- pseudomembranous colitis (stop abx if pt has diarrhea)
- most commonly used in female GU surgeries
What are the side effects of Clindamycin?
- Severe GI complications
- skin rash
- Prolonged NMB
- prolonged pre and post junctional effects at NMJ
- these effects cannot be antagonized with anticholinesterases of calcium
Vancomycin:
structure
-cidal or -static?
MOA
- Glycopeptide derivative
- Bacteriocidal
- impairs cell wall synthesis
Which surgeries require cefazolin + Metronidazole?
Head and neck ( with entry into orpharynx)
Colorectal (emergency surgery or obstruction)
Appendectomy
