Chapter 24 Flashcards
What are factors that contribute to antimicrobial resistance:
- Increases in populations of immunocompromised patients
- number and complexity of invasive medical procedures
- use of antimicrobials inappropriately (broad-spectrum, excessive duration, no indications)
- survival of patients with chronic diseases.
Leading risk factors: recent use of antimicrobials, multiple medical comorbidities, recent hospitalization or other skilled health-care contact, and immunosuppression
what is bactericidal?
99.9% eradication of a bacterial colony in vitro in 24 hours by an antimicrobial
What is bacteriostatic?
antibiotic that kills bacteria but the result is less than 99.9% eradication in a 24-hour period
What types of antibiotics fall under the beta-lactam superclass?
Penicillins
cephalosporins
carbapenems
monobactams
How does beta-lactams work?
The beta-lactam ring inhibits the biosynthesis of the bacterial cell wall, specifically the peptidoglycan structure. The beta-lactam bings do the bacterial enzymes that make the cell walls and inhibits it`
what are the four subclasses of penecillins:
natural penicillins
aminopenicillins
antistaphylococcal penicillins
antipseudomonal or extended-spectrum penicillins.
What are natural penicillins effective against?
aerobic, gram-positive organisms (streptococcus species, some enterococcus, and some non-penicillinase-producing staphylococci [5-15%])
Pasteurella multocida, Actinomyces, Clostridium, Peptostreptococcus, and Treponema pallidum
what is penicillinase? what bacteria releases this
An enzyme that hydrolyzes the beta-lactam ring of natural penicillins rendering them completely ineffective.
Staph Aureus and Haemophilus
what is Penicillin G good for?
Penicillin G is reliable for treating Listeria monocytogenes
What are aminopenicllins affective against?
Gram-positive organisms, including Streptococcus and Enterococcus species. They have greater activity against gram-negative bacteria because of their enhanced ability to penetrate the outer cell membrane of these organisms
What are the two aminopenicillins?
AMpicillin
AMoxicillin
what two beta-lactamse inhibitors are added to aminopenicillins?
clavulanic acid and sulbactam
what are ampicillin/sulbactam and amoxicillin/clavulanate great against?
methicillin-susceptible Staph Aureus, Streptococcus, enterococcus, shigella, salmonella, Neisseria meningitides.
What drugs are antistaphylcoccal penicillins?
Nafcillin (IV)
Oxacillin (IV)
Dicloxacillin (PO)
what makes antistaphylococca penicillins different than other penicillins?
Stable in the presence of penicillinase produced by staphylococci. ineffective against Enterococcus species, Listeria, and gram-negative bacteria
what are antistaphylococcal penicillins effective against?
Streptococcus species, MSSA, and Peptostreptococcu
what are the four (4) used natural penicillines?
Penicillin V
Penicillin G
Procaine penicillin
benzathine penicillin
whis the antipseudomonal penicillins
pipercillin/tazobactam!
good against pseudomonas, enterobacter, e.cold klebsiella, proteus mirabilus.
what is the absorption of penicillin class
Oral penicillin formulations are limited due to higher-than-recommended doses causing GI distress and diarrhea. (serum concentration does not increase proportionately with higher dosages)
Penicillin V (natural) and dicloxacillin (antistaphylococcal).
Amoxicillin is more absorbed.
what is peicillin’s distribution?
bounded to plasma proteins to varying degrees and well-distributed.
can penicillins cross placenta?
yes
what is the metabolism of penicillins?
Undergoes negligible metabolism and is excreted primarily in urine.
what are precautions/contraindications for penicillins?
Allergies (~10% ; <1% true allergies)
cross-reactivity likely
Type 1 allergic reactions to cephalosporins, carbapenems, or beta-lactamase inhibitors
Zosyn may induce hemorrhagic manifestations.
what are the ADR for penicillins?
Type 1 hypersensitivity (skin test!)
Gi symptoms (N/V, diarrhea)
Bacterial/fungal overgrowth of nonsusceptible organisms (with prolonged/repeat therapy).
C.diff
can be hepatotoxic (esp in HIV pts).
can be nephrotoxic (vanco + zosyn)
severe: seizures/irritability (high penicillin dose)
