Lecture 10_Spring Flashcards
(70 cards)
Give two reasons for giving Antimicrobial agents
- Prevent surgical site infection (SSI)
2. Treat known/ suspected infection
What is the difference between bacteriostatic and bacteriocidal? Which one is better for perioperative ABX?
Bacteriostatic = stops bacteria from growing & reproducing
- disrupts protein formation
- disrupts DNA synthesis-> prevents reproduction
Bacteriocidal = kills the bacteria
- better choice for perioperative ABX
- better choice for the critically ill & immunocompromised
- Disrupts cell wall or cell membrane
What is MIC (minimum inhibitory concentration)?
the minimum serum concentration that is needed to be effective.
Want to avoid under dosing bc it could promote bacterial resistance.
Exception- hepatic and renal dysfunction
What is the difference between narrow spectrum and braod spectrum ABX?
A broad-spectrum antibiotic
- acts against a wide range of disease-causing bacteria
- acts against both Gram-(+) & Gram-(-) bacteria
- in contrast to a narrow-spec which is effective against specific families of bacteria.
Narrow Spectum
- only effective against agents of concern
- minimize effects on other “normal” flora (broad spectrum)
When are broad spectrum ABXs used?
- Before the formal ID of the causative bacteria, when there is a wide range of possible illnesses and a potentially serious illness would result if treatment is delayed.
- This occurs, for example, in meningitis, where the patient can become fatally ill within hours if B.S. ABX aren’t started
- For drug resistant bacteria that do not respond to other, more narrow-spectrum antibiotics.
- In the case of superinfections, where there are multiple types of bacteria causing illness, thus warranting either a broad-spectrum antibiotic or combination antibiotic therapy.
- Empirically (i.e., based on the experience of the practitioner)
What is the difference between aerobic bacteria and anaerobic bacteria? Where are each type found in/on the body?
Aerobic = able to use O2, gets energy from breaking down food
- skin (gram +)
- gut (gram -)
Anaerobic = can sustain itself w/o O2, can’t break down food
- intestinal
- GYN
What is the difference between Gram (+) and Gram (-) bacteria?
Gram (+)
- thinner cell wall
- more easily penetrated by ABX
Gram (-)
- more resilient cell wall
- less susceptible to most ABX
Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
strep
gram +, skin
Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
staph
gram +, skin
Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
enterobacilli
gram -, gut
Identify the following aerobe as gram(+) or gram(-) and identify where it is found:
E. coli
gram -, gut
What are the three ways to classify ABXs?
Bacteriostatic vs Bacteriocidal
Narrow Spectrum vs Broad Spectrum
Gram(-) vs Gram(+)
What are the 3 types of ABX cellular targets? (sites of action)
- cell wall
- protein synthesis (ribosomes)
- nucleic acid synthesis
- What type/class of ABXs most commonly cause allergic rxns?
- What are 4 symptoms of this immune-related rxn?
- Will a test dose trigger an allergic rxn?
beta-lactams and derivatives.
rash, pruritis, bronchospasm, and anaphylaxis
Yes.
After administration of vancomycin, your patient displays the following symptoms: rash, pruritus, bronchospasm and flushing. Is your patient having an allergic reaction?
Not necessarily. They can be having a non-immune mediated histamine release. Certain drugs can cause release of histamine in a dose- and/or rate-dependent fashion. This used to be called anaphylactoid, but this term is not really used much anymore. This reaction can be just as severe as immune-mediated anaphylaxis.
Cefazolin is the preferred ABX is which 4 types of surgeries?
- Cardiac or vascular
- Neuro
- Ortho: TKA/THA
- General (hernia repair, breasts)
For a given procedure, cefazolin is the preferred ABX; however, the patient has a B-lactam allergy. What ABX should be used instead? What if the patient had a known history of MRSA?
B-lactam allergy - Clindamycin or vancomycin
MRSA - vancomycin
What types of surgeries is cefoxitin the preferred ABX? What if the pt has a B-lactam allergy?
- Colon
- General (gastroduodenal, hepatobiliary)
- Gynecological (hysterectomy, c-section)
B-lactam allergy -> gentamicin + metronidazole OR Ciprofloxacin + metronidazole
When are ABXs not indicated?
not indicated for elective “clean” surgical procedures
Name 4 ABX groups that target the cell wall/membrane.
PCNs (B-lactam)
Cephalosporins (B-actam)
Vancomycin
Daptomycin
What are beta lactamase inhibitors? Name 3 examples.
They overcome resistance to PCNs. Resistance is caused by inactivation by beta lactamases.
Unasyn, Zosyn, Aumentin
Name 3 common Cephalosporins.
Cefazolin, Cefoxitin, Ceftriaxone
What are cephalosporins excellent coverage for?
skin flora
What are cephalosporins commonly used for?
cardiovascular, orthopedic, biliary, pelvic, intraabdominal surgry
