Cleaning ourselves to death

Bacteria are everywhere! They’re even in geothermal vents and other extreme conditions of hot and cold. They’re responsible for many terrible diseases like cholera and the bubonic plague. Staphylococcus aureus, a species often associated with food poisoning, has a size close to 0.6 microns in diameter, small enough to fit approximately 1,000 individual cells on the point of a pencil. What’s the takeaway message? Bacteria are abundant, hardly detectable and wildly dangerous — we should kill as many as possible to protect ourselves! Or should we?

Not all bacteria are pathogens. In fact, if one were to consider the proportion of harmful bacteria that the average person interacts with per unit time compared to the total number of bacteria encountered, the overwhelming majority of bacteria could be considered harmless.

Many hand sanitizers advertise to kill approximately 99 percent of bacteria living on any surface. People frequently use hand sanitizers to combat the spread of the common cold and the flu. However, these antibacterial agents are arguably ineffective against the pathogens that cause the common cold and influenza because these maladies are caused by viruses, not bacteria.

Through the excessive use of antibacterial products, not only do we fail to kill the virus that causes the common cold, but we also kill many bacteria that are potentially beneficial to our health. Furthermore, should any of the harmful bacteria happen to survive the Purell bath, they will then go on to produce a new generation of bacteria that are completely immune to the original antibacterials.

Bacteria have a number of things going for them that makes the study of their genetics and evolution interesting. They have large populations and short generation times. When the above two factors are compounded, the result is a series of genetic changes that occur over a relatively small timeframe. Bacterial evolution can occur on the scale of hours to minutes, whereas humans have to wait decades.

Another source of genetic variation in bacteria comes from horizontal transfer. Even though bacterial populations exhibit objectively rapid changes from mutation, their lack of a nucleus allows for bacteria to share DNA amongst themselves. In human terms, it’d be like being able to catch blue eyes, red hair, or any other trait from one’s neighbor. For bacteria, it means passing the blueprints for new proteins, which could allow for things like virulence or drug resistance.

While not all resistant bacteria are harmful, and not all harmful bacteria are resistant, as we increase the population of one group, the chances that they’ll gain the other trait increase as well. Through excessive use of antibacterial agents, we artificially increase the proportion of the resistant population. As the resistant population grows, the chance of a resistant strain developing virulence gradually changes from a dangerous possibility to a statistical inevitability.

Don’t get me wrong, antibacterials are useful. They play crucial roles in fighting infection and preventing the spread of many diseases like tetanus and syphilis. However, there needs to be an understanding of their function and use. While judicious and measured application of antibiotic agents has improved the general quality of patient care and increased life expectancy, their abuse could lead to dangerous consequences.

ALAN LIN can be reached at science@theaggie.org.

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