Jelly - Pen G for lyme

[Guest guest]

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.