Increasing
hygiene concerns
have sparked consumer trends in prefer r ing
antibacterial soaps over more traditional ones.
The extra label provides additional reassurances
of protecting us from illnesses brought about by
harmful microbes, and thus, gives us a peace
of mind. However, do antibacterial soaps truly
outdo their counterparts, in terms of eliminating
pathogens? Whether these antibacterial soaps
are as effective as manufacturers claim them to
be deserves a closer examination in this flu season.
Let’s begin with a look into soap’s chemical
structure and functions.
Soaps fall under the category of detergents,
referring to substances with cleaning abilities
in dilute solutions. Soap molecules resemble
tadpoles, with a hydrophilic (water-loving) head
and a hydrophobic (water-hating) tail. In the
presence of lipids, the tadpole tails interact with
and enclose the lipids, while the heads irradiate
outward, interacting with the aqueous medium.
These spherical envelopes formed by the tadpole-
like detergent molecules are known as micelles.
Soap’s amphiphilic property allows it to solvate
the phospholipid membranes of bacteria with its
hydrophilic head, and the hydrophobic tail allows
the enclosed bacteria to be easily lysed. In other
words, all soaps are ‘antibacterial’. Virus capsids,
however, are composed of proteins instead of
fatty acids. Given that proteins have relatively
low affinity toward the hydrophobic tails of soap
molecules, viruses are less vulnerable to be lysed
by soap.
Antibacterial soaps (for lack of a better term),
on the other hand, often contain an active
ingredient called triclosan, differentiating it from
traditional soaps. Originally used exclusively in
hospital settings, triclosan is now found in 75%
of liquid antibacterial soaps and a slew of other
products such as wet wipes, hand gels, and
even mattresses. Its chemically stable structure
allows it to be heated to high temperatures,
making it a suitable addition to various plastic
mater ial s. Tr iclosan wor k s by react i ng with
amino acid residues at the enzyme active sites
to form ternary complexes that mimic natural
substrates. These mimics are considered abnormal
enzyme-substrate complex which in turn inhibit
the bacterial fatty acid’s biosynthetic pathway,
leading to the collapse of a series of metabolic
reactions vital to the bacteria’s survival through
protein and lipid synthesis.
Studies have shown that traditional soap and
water remove approximately 99.4% of the bacteria
on our hands. Soaps containing triclosan raise that
percentage to 99.6% - not significantly different by
any means. In fact, the addition of triclosan leads
to the potentially bigger problem of antibiotic
resistance. Since triclosan is present in trace
amounts in commercial detergents, there have
been concerns that the strongest 0.4% of bacteria
which are not killed would mutate, and develop
cross-resistance to not just triclosan, but other
antibiotics as well. The good news is that while
signs of resistance were found in the laboratory, it
has yet to be observed in the environment for such
an experiment would be difficult to execute.
Despite the fact that antibacter ial soaps
have a slight edge over traditional ones, the
question remains whether they add much to
the promotion of hygiene. Cold-like symptoms
are also more often caused by viruses than
bacteria, and soaps in general are less
effective in eradicating viruses. While the use
of antibacterial soaps has its benefits for people
with compromised immune systems where that
extra edge is necessary, most homes should be
adequately equipped against pathogens with
traditional soaps. After all, good hygiene is really
brought about by regular handwashing rather
than specialised soaps.
