Why is Rifampin bactericidal?

[auburnO5]

---

Members don't see this ad.

Not sure if this is the place to ask this... but...



We were told that Rifampin is bactericidal.

The mechanism of action for Rifampin is that it binds to the B subunit of bacterial RNA polymerase which inhibits RNA synthesis.

I don't understand why that wouldn't make Rifampin bacteriostatic?

If anybody has an opinion on this, I would like to hear it!

 

[RedSHIFT]

Not sure if this is the place to ask this... but...



We were told that Rifampin is bactericidal.

The mechanism of action for Rifampin is that it binds to the B subunit of bacterial RNA polymerase which inhibits RNA synthesis.

I don't understand why that wouldn't make Rifampin bacteriostatic?

If anybody has an opinion on this, I would like to hear it!

Rifampin is bactericidal.

troll

 

[auburnO5]

Rifampin is bactericidal.

troll

Thanks for the help!

 

[greatnt249]

Not sure if this is the place to ask this... but...



We were told that Rifampin is bactericidal.

The mechanism of action for Rifampin is that it binds to the B subunit of bacterial RNA polymerase which inhibits RNA synthesis.

I don't understand why that wouldn't make Rifampin bacteriostatic?

If anybody has an opinion on this, I would like to hear it!

Concentration is really more of a key player in determining whether a compound is bactericidal or bacteriostatic, but rifampin forms a pretty stable complex with the beta subunit.

 

[Mean Muggin]

If you can't make proteins, you die.

 

[werd]

there are probably some hypotheses out there, but i think the most honest answer is noone really knows. why are tetracyclines static and aminoglycosides cidal? their mechanisms are very similar. why are most macrolides static but telithromycin (pulled from market) is a cidal macrolide? it's interesting but largely unknown stuff..

 

[auburnO5]

If you can't make proteins, you die.

Erythromycin, Clindamycin, and Tetracyline all bind to ribosomal subunits preventing protein synthesis, and they are static.

 

[LRAccord624]

Erythromycin, Clindamycin, and Tetracyline all bind to ribosomal subunits preventing protein synthesis, and they are static.

This may reflect the strength of the bond with the ribosomal subunit, as pointed out by greatnt249.

However, I wonder those things all the time. I have a hard time straight memorizing without being able to visualize or know "why". Also, I suck ass at biochemistry and I'm glad that I took that final first. Now lets that I don't have to remediate... come on 9th percentile in the nation... lol

 

[Mean Muggin]

Erythromycin, Clindamycin, and Tetracyline all bind to ribosomal subunits preventing protein synthesis, and they are static.

I think it has to do with the tightness of the binding and the fact that rifampin blocks transcription initiation, so it's hitting things further "upstream" than Erythromycin, clindamycin, and tetracycline. If you can still make mRNA and you have drugs that are reversibly inhibiting ribosomes, then you can still get protein through, albeit at a much reduced level. Also, according to Murray, rifampin is bactericidal specifically for M. tuberculosis.

 

[greatnt249]

I think it has to do with the tightness of the binding and the fact that rifampin blocks transcription initiation, so it's hitting things further "upstream" than Erythromycin, clindamycin, and tetracycline. If you can still make mRNA and you have drugs that are reversibly inhibiting ribosomes, then you can still get protein through, albeit at a much reduced level. Also, according to Murray, rifampin is bactericidal specifically for M. tuberculosis.

This. The goal is to slow growth long enough for your immune system to have a crack at taking down the infection, but as you know, OP, you wind up with caseating granulomas if you take this approach with TB.

 

[greatnt249]

We were told that Rifampin is bactericidal. The mechanism of action for Rifampin is that it binds to the B subunit of bacterial RNA polymerase which inhibits RNA synthesis. This is main fundamental knowledge of Rifampin . So don't forget ever this. This is the very important thing. Here the basic knowledge provides here.

This...doesn't really answer the OP's question. Yes, we know the mechanism of how rifampin works; the question is WHY rifampin is considered bactericidal when other antibiotics interfere with bacterial protein synthesis as well, yet are considered bacteriostatic.

 

[itellitlikeitis]

Concentration is really more of a key player in determining whether a compound is bactericidal or bacteriostatic, but rifampin forms a pretty stable complex with the beta subunit.

Well greatnt already touched on it- it has to do with the concentration

Rifampicin may be bacteriostatic or bactericidal depending on the concentration of drug attained at site of infection.

The bactericidal actions are secondary to interfering with the synthesis of nucleic acids by inhibiting bacterial DNA-dependent RNA polymers at the B-subunit thus preventing initiation of RNA transcription, but not chain elongation. (Fahr et al., 1985; Drug Information for Health Care Provider, 1984).

the other thing you can do is shoot the professor who told you the info an email asking your very same question you're asking here...

 

[275471]

We were taught that rifampin is cidal only against bacteria that are rapidly dividing and otherwise static. I think this makes sense within the context of everything else already discussed