Why Do Bacteria Develop Antibiotic Resistance?

Why Do Bacteria Develop Antibiotic Resistance?


Despite their beauty, roses always seem to
cause innocuous little cuts with their sharp thorns. But let’s flashback to the 1930s. If bacteria managed to get into the bloodstream
through that cut, it could have been disastrous since antibiotics had yet to become widely
available. Fast-forward to today, and we wouldn’t think
twice about a small cut thanks to our arsenal of antibiotics, drugs that interrupt normal
bacterial physiology. But they’re no simple miracle, as resistance
to these compounds is growing at an alarming rate. While humans have a generation time of 20
to 30 years, bacteria such as E coli can double in as little as 20 minutes. This rapid growth and the selective pressures
to survive in their environment, favor the development of genetic mutations for antibiotic
resistance. Our rampant use of antibiotics only serves
to exacerbate the problem. Though we associate antibiotics with curing
diseases, it’s estimated that 70% of our antibiotics are used in healthy animals as
growth promoters. An additional 15% are used inappropriately
in humans, either for infections that they cannot treat or as unfinished regimens. It’s this completely unnecessary use which
is fueling the rapidly growing resistance. Imagine a group of bacteria being exposed
to antibiotics in our body. The longer they’re exposed to high doses
of the drugs, the more bacteria are killed off. But if the antibiotics are suddenly withdrawn,
say on day 4 of a 7 day antibiotic course, the surviving bacteria may develop resistance
to a sub-lethal amount of the drug and then multiply. What started as a colony of antibiotic susceptible
bacteria is now a colony of antibiotic resistant bacteria. In livestock, sub-lethal doses of antibiotics
are used constantly, some of which runs off into rivers and other waterways, to create
a breeding ground for antibiotic resistance. The dangers of using antibiotics in livestock
is exemplified by a drug known as Synercid. The drug was approved for use in humans in
1999, but a close relative known as virginiamycin had been used for years to plump up animals. Before Synercid reached the market, studies
in Michigan, Wisconsin, Maryland, Germany, and Denmark, to name just a few, all found
in animal feces, bacterial colonies that were resistant to Synercid. CDC investigators later purchased chickens
from twenty-six different grocery stores and found that over half of them had Synercid
resistant bacteria. In 2006, researchers in Minnesota tested samples
of conventional poultry raised on virginiamycin and antibiotic free poultry, as well as stool
samples of meat-eating patients and vegetarians. The majority of bacterial colonies from the
conventional poultry were resistant to Synercid, compared to only a few in the antibiotic-free
poultry. Additionally, the samples from the meat-eating
patients had higher rates of Synercid resistant bacteria than those from the vegetarian patients. These studies suggest that using antibiotics
as growth promoters in animals can lead to antibiotic resistant bacteria, which may eventually
go on to infect humans. To make matters worse, only two new classes
of antibiotics have been approved for use in the past 50 years, compared to 20 between
1940 and 1962, meaning our innovation hasn’t kept up with bacterial resistance. So what can you do to help slow down the development
of resistance? While the 70% of antibiotics used to promote
growth in animals may be difficult to combat, the 15% used inappropriately in humans can
be addressed now. Antibiotics have no effect on viral infections
like the common cold, so physicians should not prescribe them if they’re not warranted. Additionally, patients given antibiotics should
use the fully prescribed amount, even if their symptoms have already resolved, to prevent
mutations and reinfection. Antibiotic resistant bacteria undermine sustainable
food production, are more expensive to treat, and kill over 20,000 people annually in the
United States alone. If action is not taken soon, antibiotic resistance
will continue to grow, and even simple actions such as handling a rose may turn into a dangerous
prospect.

One Reply to “Why Do Bacteria Develop Antibiotic Resistance?”

Add a Comment

Your email address will not be published. Required fields are marked *