Antibiotics: Penicillins--weaken bacterial cell wall Flashcards
describe two ways that penicillin weakens the bacterial cell wall
- Inhibition of transpeptidases
Transpeptidases are enzymes critical to cell wall synthesis. If no transpeptidase, then the cell wall can hold itself up and it falls apart. - Disinhibition (activation) of autolysins.
Autolysins are bacterial enzymes that cleave bonds in a cell wall.
By simultaneously inhibiting transpeptidases and activating autolysins, penicillin’s disrupt synthesis of the cell wall and promote it’s active destruction.
list and explain ways microbes might be resistant to penicillin.
- Inability of penicillin’s to reach their targets (PBPs) – G+ IMPENETRABLE
penicillin’s can break through the gram negative cell wall easily, as there are only two layers. but the gram positive cell wall contains an outer membrane which can be difficult to penetrate for the penicillin’s. - Penicillinases (beta-lactamases)–BREAK THE BETA LACTAM RING
penicillin’s have a beta lactam ring that helps them hold their shape and be effective. bacteria produce a large variety of beta-lactamases, enzymes that cleave the beta-lactam ring. some of the beta lactamases are specific to penicillin’s (penicillinases). if a penicillin is hit by a beta lactamase, it is rendered useless because it’s integral chemistry is lost. - Altered Penicillin Binding Proteins– GAR
penicillin’s bind to their targets in a specific way to cause cell injury and death. MRSA has developed a unique way to resist penicillin: by producing PBP’s with a low affinity for penicillin and almost all other beta-lactam antibiotics. MRSA got this ability by acquiring genes that cod for low affinity PBP’s from other bacteria.
Describe drug allergy to penicillin, including types of allergic reactions.
penicillin’s are the most common cause of drug allergies in patients. Doesn’t need prior exposure to have an allergic reaction, but responses may occur with prior penicillin use. patients allergic to one penicillin should be considered allergic to all penicillin’s d/t cross sensitivity.
types of allergic reactions:
immediate:2-30 minutes after drug administration
anaphylaxis will come with an immediate reaction, treat with epinephrine and respiratory support.
accelerated: 1 to 72 hours after drug administration
delayed: within days to weeks after drug administration
define MRSA and contrast hospital acquired MRSA with community acquired MRSA.
MRSA is methicillin-resistant staphylococcus aureus.
hospital acquired MRSA is different than community acquired MRSA because it is more prevalent, more serious, and harder to treat. Often people in the community will contract MRSA d/t exposure they have had at a healthcare facility. Transmission is through person to person contact, most likely between HCWs and patients. risk factors/people are advanced age, recent surgery or hospitalization, dialysis, treatment in an ICU, prolonged antibiotic therapy, indwelling catheter, and residence in a long term care facility.
community acquired MRSA has genetically distinct strains, people are asymptomatic carriers, causes mild infections mostly, transmission is by skin to skin contact. risk factors/people are athletes in contact sports, gay men, people who live in close quarters (prison inmates, military personnel and college students)
both of these do not respond to beta lactam antibiotics, except CA-MRSA responds to ceftaroline.
what type of penicillin are amoxicillin and ampicillin?
they are broad-spectrum penicillin’s (aminopenicillins)
list four different points you would include on patient teaching about penicillin’s.
- complete prescribed course of treatment, even if they feel better
- take oral penicillins with a full glass of water 1 hour before meals or 2 hours after.
- advise patients with penicillin allergy to wear some form of identification (med alert bracelet) to alert emergency healthcare personnel.
- instruct outpatients to report any signs of an allergic response (skin rash, itching, hives).
