How do we keep bacteria from
resisting antibiotics?
Anyone undergoing a pre-admission
assessment for surgery is now routinely
swabbed for MRSA – Methicillin-
Resistant Staphylococcus aureus. S.
aureus are skin- and nose-dwelling
bacteria. They are part of the normal
cohort of micro-organisms we carry
around with us and aren’t necessarily a
threat, but if they are introduced into the
interior of the body – the bloodstream,
for instance – serious illnesses such as
septicaemia and pneumonia can occur.
MRSA are germs that have evolved,
via random mutations, to get around
the way antibiotics work. Antibiotic
resistance is a serious problem: indeed, it
is referred to by some as the public health
problem of the 21st Century.
While MRSA might be considered
a new disease, the ancient scourge
of tuberculosis, caused mainly by
Mycobacterium tuberculosis, has been
made more fearsome as MDR (multi-
drug resistant) or XDR (extremely
drug resistant) tuberculosis because of
antibiotic resistance. In areas with a high
burden of HIV/AIDS, such as sub-
Saharan Africa or parts of Asia, and in
tuberculosis ‘hotspots’ in the developing
world, the disease has become a renewed
threat to health.
In the wake of the first successful
anti-tuberculosis drug, streptomycin
(developed during World War II), it
was quickly realised that if streptomycin
was given alone, resistance would arise.
With the advent of further drugs, a
cocktail approach was adopted. Since
the mutations leading to resistance
are not linked, the chance of any onebacterium becoming resistant to all of
the drugs prescribed is extremely low,
so long as the patient continues to take
their protracted course of unpleasant
drugs to completion. In countries where
healthcare systems cannot ensure that
patients do this, unfinished courses of
drugs, buying inadequate courses of
antibiotics, counterfeit drugs and shared
prescriptions all encourage resistance.
Our battle against drug-resistant
bacteria will probably always be a cat
and mouse affair. A continuous supply of
new drugs will help, and since bacteria
react to different drugs in varying ways,
giving a cocktail of several medicines
is essential.How do we maintain ‘good’
bacteria in our guts?
What is called our gastrointestinal tract,
from our mouths to our anuses, is both
part of our bodies but also open to the
outside world. If you find bacteria in
the blood or cerebral spinal fluid, it is
evidence of disease. But the mouth and
the colon teem with them. Even the
stomach, long thought to be so acidic
that bacteria could not survive there, is
now known to harbour them.
The large intestine is home to many
different species of bacteria and eating
yogurt to encourage the ‘good’ bacteria
there has a history of more than a
century. We know that there are far
more bacteria in our guts than cells in
our bodies. However, we don’t know
how many different species there are.
Probably the best estimate is that there
are perhaps 500 different species. New
ones are regularly being discovered:MEDICAL
BACTERIOLOGY
a recent one was so unlike any other
known bacterium that it was assigned its
own phylum: Melainabacteria.
Gut bacteria provide an important
function, helping to continue the process
of digestion of foodstuffs that begins
in the mouth. Some of the breakdown
products of the ‘good’ bacteria are also
essential to us, producing vitamin K and
some of the vitamin B complex. And
‘good’ bacteria are also important inPHOTO: GETTYThere are more bacteria in your body than there are
cells. William Bynum looks at our close relationship
with them and their surprising new medical usesBACTERIA
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