Several days ago, someone on BEE-L asked the question "how do bacteria
develop resistance to antibiotics if they don't breed through sexual
reproduction?"  The answer given at the time was "through the process of
mutation".
 
I'm certainly no molecular biologist, but I would like to share with
BEE-L readers an article written by one of my colleagues which explains
how bacteria actually develop resistance.  It seems they do it through
the process of "conjugation", or the sharing of DNA in plasmids.  
 
The article was written in relation to trials being conducted in New
Zealand on the antibacterial properties of honey (ie, antibacterial
compents inherent in honey, not antibiotics added to the honey) --
 
BACTERIAL RESISTENCE AND HONEY
 
The development of antibiotic resistance by bacteria is a major concern
to world health.  The antibacterial properties of honey are now being
investigated because honey may give us another weapon in fighting
bacteria which have become resistant to man-made antibiotics.  Some
floral sources of honey have been able to inhibit the growth of some of
the most concerning resistant bacteria under strict laboratory trials.
 
What causes bacteria to become resistant to antibiotics?  
 
Within some bacteria are small circular DNA strands known as plasmids. 
These are simply two small complementary DNA strands in a circle.  Each
of these circles contain a few thousand molecules of DNA material known
as bases.  These bases combine together to form DNA strands in such a
way that they can act like a ‘blue print’ for the formation of proteins
that can have important functions in the bacteria.  
 
This information is contained in a unit known as a gene.  A gene may
carry information for the inactivation of an antibiotic drug.  There can
be a number of different genes in a plasmid, all forming proteins that
can inactivate antibiotics.
 
Plasmids are found in the bacterium separate to that of the bacterium’s
main DNA chromosome.  A chromosome is the term for the DNA when it is
packed away within the bacterium.  Plasmids, on the other hand, are not
always necessary for the bacterium’s survival.  But the plasmid can be
responsible for inactivation of an antibiotic by blocking the mechanism
of the antibiotic.  The blocking is undertaken by a protein formed in
the bacterium as a result of the information contained in a gene on the
plasmid’s DNA complex.
 
This information can be passed on from one bacterium to another in a
process known as ‘conjugation’.  This is when two bacteria come together
and a single DNA strand from the plasmid’s duplex separates and moves
though to the reciprocating bacterium.  Once in the hosting bacterial
cell, both single strands are matched up by new DNA molecules that
complement the DNA bases.  The plasmid becomes once again a
double-stranded DNA circle.
 
This sharing of information is very important to the survival of
bacteria and is the reason medical people are so concerned about the
future of antibiotics.  Whole wards in hospitals have been quarantined
as a result of resistant bacterial outbreaks.  Without a way to fight
these bacteria people can suffer serious infections and even die.
 
Honey trials conducted under very strict controls at the Waikato
Hospital have shown that  honey of differing floral sources can have an
effect on resistant strains of bacteria.  In a number of cases the
effect has been total inhibition of growth.  This is quite exciting
since it promotes possible future reasons to use some honeys as wound
dressings.  Cases have already been reported were the use of honey has
healed wounds which have not responded to other conventional treatments.
 
Honey has been used in medical situations for centuries.  However, with
good medical research we may see it accepted by even the most critical
members of medical community.
 
[Article written by James Driscoll, Apicultural Advisory Officer,
Palmerston North]