Re: Jelly - Pen G for lyme - bicillin

[Guest guest]

Hold the phone, somethings odd here. Apparantly Bicillin, which IS

used for lyme, is not benzylpenicillin but is metabolized to

benzylpenicillin in the body. So perhaps the in vitro data I cited

below have been disconfirmed, or perhaps the Bicillin prodrug is

itself active against Bb, or something else. Arguably I should take

care of my chemistry finals before diggin into the issue.

> You asked if the chief syphilis drug, penicillin G

(benzylpenicillin),

> has been used for lyme. This brings up important observations.

>

> The syphilis agent Tp is equally - and highly - suceptible to both

> benzylpenicillin and ceftriaxone in vitro. Bb is just as sensitive

to

> ceftriaxone - but evidently is 100x less sensitive to

benzylpenicillin:

>

> http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=174684

>

> Differences in suceptibility to different B-lactam drugs are

usually

> ascribed to the fat- or water-solubility of the drugs affecting

their

> penetration of the cell envelope. Apparantly fat-soluble drugs are

> much less active against typical gram-negative organisms because

they

> have difficulty passing the water-soluble LPS coat of the outer

> membrane. FOr one thing I'm not sure that theory is 100%

theoretically

> sound in itself, and for another, both Bb and Tp lack LPS. The

fitness

> of these drugs as substrates for bacterial efflux pumps may be of

> significance in these observations, which constitute an intriguing

> difference between these not-terribly-closely-related organisms.