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NURS 5344 ANTIMICROBIALS FLASHCARD WITH
CORRECT ANSWERS 2024-2025
How do antibiotics promote resistance?
(1) microbes secrete compounds that are toxic to other microbes, and (2)
microbes within a given ecologic location (e.g., large intestine, urogenital tract,
and skin) compete with each other for available nutrients. Under drug-free
conditions, the various microbes in a given region keep each other in check.
Furthermore, if none of these organisms is drug resistant, introduction of
antibiotics will be equally detrimental to all members of the population and,
therefore, will not promote the growth of any individual microbe. However, if a
drug-resistant organism is present, antibiotics will create selection pressure
favoring its growth by killing off sensitive organisms.
Which antibiotics promote resistance?
All antimicrobial drugs promote the emergence of drug-resistant organisms.
Broad-spectrum antibiotics kill more competing organisms than do narrow-
spectrum drugs, therefore broad-spectrum agents do the most to facilitate
emergenceof resistance.
What is conjugation?
Conjugation is a process by which extrachromosomal DNA is transferred from one
bacterium to another.
Penicillin MOA
Beta-lactam antibiotics weaken the cell wall, causing bacteria to take up excessive
amounts of water and rupture. They are bactericidal
How microbes resist drugs
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(1) decrease the concentration of a drug at its site of action, (2) alter the structure
of drug target molecules, (3) produce a drug antagonist, and (4) cause drug
inactivation.
What does the NDM-1 gene do?
Extensive drug resistance is conferred by the NDM-1 gene, which codes for a
powerful form of β-lactamase. It can inactivate essentially all β-lactam antibiotics,
a group that includes penicillins, cephalosporins, and carbapenems. Because
the NDM-1 gene is resistant to carbapenems, it is also classified as a type of
carbapenem-resistant Enterobacteriaceae (CRE).
Bacterial resistance to penicillin
(1) inability of penicillins to reach their targets (PBPs), (2) inactivation of
penicillins by bacterial enzymes, and (3) production of PBPs that have a low
affinity for penicillins.
Penicillin G Activity
Penicillin G is active against most gram-positive bacteria (except penicillinase-
producing staphylococci), gram-negative cocci (Neisseria meningitidis and non–
penicillinase-producing strains of Neisseria gonorrhoeae), anaerobic bacteria, and
spirochetes (including Treponema pallidum). With few exceptions, gram-negative
bacilli are resistant.
Penicillin G
narrow spectrum penicillin
least toxic antibiotic
given IV or IM
Procaine Penicillin G can cause behavioral effects
potassium Penicillin G may cause hyperkalemia
Patients who have a penicillin allergy might have a cross-allergy to?
Cephalosporins
Penicillin immediate reaction
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occur 2 to 30 minutes after drug administration
mediated by immunoglobulin E (IgE) antibodies.
Penicillin accelerated reaction
accelerated reactions occur within 1 to 72 hours
mediated by immunoglobulin E (IgE) antibodies
Penicillin delayed reaction
reactions occur within days to weeks.
Penicillin V aka VK
penicillin V has replaced penicillin G for oral therapy. Penicillin V may be taken
with meals.
Narrow spectrum?
narrow-spectrum penicillins that are penicillinase resistant (antistaphylococcal
penicillins)
nafcillin, oxacillin, and dicloxacillin
group of penicillins that are highly resistant to inactivation by β-lactamases.
Broad-spectrum penicillin (aminopenicillins)
ampicillin and amoxicillin
active against most gram-positive bacteria (except penicillinase-producing
staphylococci), gram-negative cocci (Neisseria meningitidis and non–penicillinase-
producing strains of Neisseria gonorrhoeae), anaerobic bacteria, and spirochetes
(including Treponema pallidum), certain gram-negative bacilli,
including Haemophilus influenzae, Escherichia
coli, and Salmonella and Shigella species. Ineffective for S. Aureus
Ampicillin
drug is useful against infections caused by Enterococcus fecalis, Proteus mirabilis,
E. coli, Salmonella and Shigella species, and H. influenza The most common side
effects are rash and diarrhea, both of which occur more frequently with ampicillin
than with any other penicillin.
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Amoxicillin
When oral therapy is indicated, amoxicillin is preferred. Amoxicillin causes milder
diarrhea when compared with ampicillin, probably because less amoxicillin
remains unabsorbed in the intestine.
Extended-spectrum penicillin (antipseudomonal penicillins)
Piperacillin
Pseudomonas aeruginosa, Enterobacter species, Proteus species (indole
positive), Bacteroides fragilis, and many Klebsiella species, most gram-positive
bacteria (except penicillinase-producing staphylococci), gram-negative cocci
(Neisseria meningitidis and non–penicillinase-producing strains of Neisseria
gonorrhoeae), anaerobic bacteria, and spirochetes (including Treponema
pallidum), certain gram-negative bacilli, including Haemophilus influenzae,
Escherichia coli, and Salmonella and Shigella species.
Piperacillin
Not effective against S. Aureus
Piperacillin can cause bleeding secondary to disrupting platelet function.
Given by IV
β-lactamase inhibitors
sulbactam, tazobactam, and clavulanic acid (clavulanate)
inhibit bacterial β- lactamases
Only one fix dose combos: Ampicillin/Sulbactam; amoxicillin/clavulante,
piperacillin/tazobactam.
Cephalosporins
β-lactam antibiotics
These agents bind to penicillin-binding proteins (PBPs) and, hence, (1) disrupt cell
wall synthesis and (2) activate autolysins (enzymes that cleave bonds in the cell
wall). The resultant damage to the cell wall causes death by lysis. As in the case of
the penicillins, cephalosporins are most effective against cells undergoing active