cell wall inhibitor Flashcards
How Do Beta Lactams Kill Bacteria?
inhibit cell wall synthesis- inhibit the formation of peptidoglycan in which without it the bacteria would lyse
provides stability by virtue of highly cross-linked latticework structure.
peptidoglycan
Beta-lactams inhibit the family of enzymes involved in ___________
final stage of cell wall synthesis
transpeptidation or cross linkage
how are the enzymes involved in the final stage of cell wall synthesis detected
by penicillin binding proteins that covalently bind to the enzymes
Beta lactams lead to _____________ resulting in cell wall digestion and lysis of bacterial cell
dysregulation of autolysins
Beta-lactams are generally
bactericidal
3 mechanisms of resistance
- inactivation of antibiotic by a bacterial enzyme called beta-lactamase
- alteration of target site- low affinity of PBs
- decreased penetration to target site- such as gram negative bacili
B-lactam antibiotics work best at
time-dependent killing: lower yet more frequent dosing effective … just above the MIC but steady dose
- they have a short half life
- excreted by the kidneys
allergic reactions in beta lactams
common:
- immediate allergic rxn.- IgE mediated (less common)
- late allergic rxn (more common)
Narrow-spectrum
Low cost
Favorable therapeutic index
Excellent tissue penetration
penicillin
what do all of these have in common:
Staphylococcus aureus
Neisseria gonorrhoeae
Streptococcus pneumoniae
they are bacteria that we no longer use penicillin to treat due to increase resistance issues
Main use is against penicillinase-producing Staphylococcus aureus
and it is a truly narrow-spectrum agent
oxacillin
- synthetic penicillin created to treat a. aureus but there are some activity to streptococci
oxacillin active against MRSA?
nope
which is the only agent in the beta lactam family of antibiotics that treat MRSA?
ceftaroline
- Similar spectrum of activity as penicillin plus
- More active against enterococcus
- Active against Listeria monocytogenes
- Additional coverage of some gram negative bacilli: Haemophilus influenzae, some E. coli, Proteus species.
Amoxicillin
ampicillin is used to treat
meningitis secondary to listeria monocytogenes
Due to the potential production of beta-lactamases, all Haemophilus isolates should undergo sensitivity testing
yep
Clavulanic acid and sulbactam are potent inhibitors of many beta-lactamases
thus when combined with beta-lactamases they
increase the spectrum
By a complex interaction, it functions as a suicide inhibitor, meaning it serves as a target for the beta-lactamase enzyme thereby blocking the enzymatic breakdown of amoxicillin by beta-lactamases. This leaves the amoxicillin intact and able to inhibit the bacteria.
Clinical Uses of Intermediate Spectrum β-Lactams + β-Lactamase Inhibitors: Ampicillin-sulbactam
intra-abdominal and pelvic infections
Active against many gram negative organisms including Pseudomonas aeruginosa and Enterobacter spp.
Active against gram positive organisms such as streptococci
broad-spectrum penicillin
Broad Spectrum PCNs: Addition of β-Lactamase Inhibitors
are used as well in intraabdominal infections but this one is preferred is there are resistant gram negative organism
In diverticulitis, antibiotics should cover “mixed flora” – gram positives, gram negatives and anaerobes
thus what is a good choice
ampicillin-sulbactam
spectrum of B-lactam ring anitbiotics are determined by the
side rings
serum sickness is an adverse effect of beta lactams… what type of rxn is it?
it is a late allergic rxn thus we tend to see fever, rash, arthritis and circulating immune complexes
moribiliform rash beta lactam adverse effect
delayed rxn
what is the antibiotic that is preferred for Staph. aureus- methicillin sensitive
oxacillin
antibiotic against Pseudomona aurginosa
piperacillin/tazobactam
