Lesson on sulfonamide antibiotics like Trimethoprim-Sulfamethoxazole (Septra), what bacteria sulfonamides target, the mechanism of action of sulfonamides, and adverse effects of sulfonamides. Trimethoprim-sulfamethoxazole (Septra) is a sulfonamide
Everyone this lesson is on sulfa or sulfonamide antibiotics and in this that’s where i talk about what are some of the bacteria that these antibiotics target how these antibiotics work and finally what are some of the side effects of using these antibiotics so let’s get started sofa or sulfonamide antibiotics for the first synthetic antibiotics and one example is
Something with foxes all sulfamethoxazole itself is typically combined with trimethoprim and trimethoprim itself is an inhibitor of folic acid synthesis and when we combine these two we call it trimethoprim sulfamethoxazole or you might have heard of cetera these antibiotics have good gi absorption and are well distributed and they can cross a blood-brain barrier
In small proportions and they are readily excreted so trimethoprim soft methoxy zahl can cover grande positive a robes like streptococcus pyogenes or group a strep and you can see here that they are gram positive cocci in chains that is what streptococcus is can also cover pneumococcus and mssa and typically the antibiotics like scepter aren’t you specifically for
Targeting mssa but they can cover these bacteria now receptor can also cover gram-negative aerobes like the gram negative rod ecoli can also cover enterobacter shigella salmonella tomasulo’s influenza moraxella catarrhalis neisseria meningitidis so other ones include chlamydia and listeria and some of the couple important for special populations include toxoplasma
And pneumocystis coverage so in patients with aids scepter it can be used to cover or prophylaxis toxoplasma and pneumocystis pneumonia so that’s very important to know as well so couple important points to note about sulfa antibiotics are that they have no activity against pseudomonas and they have no activity against anaerobes so all the bacteria we listed
Before except pseudomonas and and anaerobes so because we’re covering a lot of the gram-negative rods like e-coli typically the infections that are treated with cetera include utis we talked about this before pneumocystis pneumonia particularly aids patients it can also be used for sinusitis and otitis media because trimethoprim soft my thoughts is all covers h
Flu and marcela and also it can cover or treat infections like prostatitis so what is the mechanism of action of trimethoprim sulfamethoxazole well when we combine these two drugs they have both bacteriostatic and bacteria sidle properties and they both are involved in inhibiting the folate synthesis pathway in bacteria so on amides like soft methos all act as
Para amino benzoic acid or paba analogues and trimethoprim itself inhibits the dihydrofolate reductase enzyme in the folate synthesis pathway as well so where do these all come into play in the bacterial folate synthesis pathway so in the folate synthesis pathway in bacteria we have die high dropped ro aid diphosphate being acted on by die high drop correlate
Synthetase with paba that then leads to after a couple of steps the production of dihydrofolate which then gets acted on by the enzyme dihydrofolate reductase to produce tetrahydrofolate so so fon amides like sulfamethoxazole act on the enzyme dihydrofolate synthetase by acting like a paba analog so this enzyme picks up the sulfamethoxazole as if it was pappa
But it doesn’t do anything so it really inhibits this step in the pathway and the trimethoprim itself inhibits the dihydrofolate reductase step so when we use these two combined they act in a synergistic way and have increased f efficacy in inhibiting this pathway so what are some of the adverse reactions he using these antibiotics the first one i want to discuss
Is stevens-johnson syndrome and stevens-johnson syndrome is a skin reaction causing a fullest ring and exfoliate ‘iv processes and it’s on a spectrum with toxic epidermal necrolysis or tens and it can be a very severe condition other common side effects so stevens-johnson syndrome is a rare reaction to sulfa antibiotics but more common adverse reactions include
Nausea vomiting and diarrhea and another read of reaction is hepatitis now before i end i want to discuss pregnancy now sulfonamide antibiotics are contraindicated in pregnancy because they act as teratogen x’ and they can also cause kernicterus in the developing fetus so we avoid sulfonamide antibiotics in pregnancy so i hope you found this lesson helpful that
Was a lesson on sulfonamide antibiotics if you did find this lesson helpful please like and subscribe for more lessons like this one and also check out some of my other antibiotic lessons in my infectious disease playlist thank you so much for watching and i hope to see you next time
Transcribed from video
Sulfonamide Antibiotics | Bacterial Targets, Mechanism of Action, Adverse Effects By JJ Medicine