soaps. Moreover, since fentichlor has a low oral toxicity, it can be used internally for skin
infections. Inhibition of the metabolic electron-transport chain and of amino acid uptake
also constitutes the bacteriostatic action of fentichlor.
Cationic detergents such as cetyl-trimethylammonium chloride (9.63) are more
effective than anionic soaps such as sodium dodecylsolfonate (9.64, SDS). Nonionic
detergents such as Triton X-100 (9.65, octoxynol or (polyethylene glycol) 10 −−
p-isooctylphenyl ether) are very mild, and are used to disperse membranes rather than
to kill bacteria. Chlorhexidine (9.66), a chlorophenyl-biguanidine derivative, is a very
effective compound. It has very low mammalian toxicity and is widely used as a wound
and burn antiseptic and surgical disinfectant. Because the imino group of the biguani-
dine moiety becomes protonated by salt formation, the compound is a cationic deter-
gent. Low concentrations (10–100 μg/ml) cause a rapid release of cytoplasmic material
from the bacterial cell. At concentrations as low as 1 μg/ml little leakage is seen, but
chlorhexidine is still active because it inhibits the membrane-bound ATPase of bacteria.
9.4.3 Antibacterials Targeting Bacterial Protein SynthesisLike other cells, bacteria must biosynthesize proteins in order to survive. Proteins are
biosynthesized following the arrival of an mRNA message to an organelle in the cytoplasm,
called a ribosome. In making proteins, the ribosome employs two of its structural units,
the 30S and 50S subunits. Molecules capable of blocking this process within bacteria
are putative antibacterials.
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