In article <4sj21c$j2r at milo.mcs.anl.gov> Mark Fuller <mark_fuller at qmgate.anl.gov> writes:
>From: Mark Fuller <mark_fuller at qmgate.anl.gov>
>Subject: Chloramphenicol resistance
>Date: 17 Jul 1996 15:49:00 GMT
>Organization: Argonne National Laboratory
>Message-ID: <4sj21c$j2r at milo.mcs.anl.gov>
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>Xref: magnus.acs.ohio-state.edu bionet.microbiology:6607 sci.bio.microbiology:4023 sci.bio.misc:3908 bionet.toxicology:792 sci.research:12437
>Does anyone have a few references to the mechanism by which
>chloramphenicol (and other nitroaromatic antibiotics) are rendered
>ineffective. I've heard of low membrane permeability, active transport
>of Chl out of the cell and acetylation, but I don't have any of the
>references for these. Also, are gram-positive organisms likely to be
>more sensitive to chloramphenicol/nitroaromatic compounds?
>Any help would be much appreciated.
>Mark Fuller, Ph. D.
>Environmental Research Division ER/203-J070
>Argonne National Laboratory
>Argonne, IL 60439-4843
>>phone: (708) 252-1795
>FAX: (708) 252-8895
>email: mark_fuller at qmgate.anl.gov
Hi Dr. Fuller,
From _Drug Evaluations, Annual 1995_ published by the AMA, p.1529.
"Chloramphenicol resistance among most gram-negative bacilli is due to drug
inactivation by an acetyl-transferase that is R-factor mediated. Resistance
in gram-positive bacteria appears to develop by a similar mechanism but is
less well understood. Pseudomonas aeruginosa and some strains of Proteus and
Klebsiella become resistant through a nonenzymatic mechanism involving an
inducible change in permeability that blocks the entry of chloramphenicol into
the bacterial cell."
From the same source, S.pneumococcus, S.pyogenes, S.agalactiae, and viridans
strep are usually susceptible, with enterococci being variably susceptible.
S.aureus usually susceptible, varies with regional utilization patterns. MSRA
usually resistant. Peptococcus and Peptostreptococcus are susceptible.
Bacillus spp, Listeria, Corynebacterium, clostridia spp, and Eubacterium are
all susceptible. Most Neisseria strains (meningitidis and gonorrhoeae) are
susceptible, as is H.influenza. A wide spectrum of other gram negatives are
susceptible, with certain Enterobactericiae developing resistance with local
patterns of use (spec. S. typhi epidemic in Mexico early 1970's)
Hope this helps