Drug-Resistant Bacteria—A Global Health Issue

Could a scraped knee land you in the hospital?

A bicyclist falls, scrapes his knees, and within a few days is unable to walk. Soccer players with turf burns suddenly find themselves in the hospital with skin infections that require
intravenous antibiotics. Why are these young, healthy athletes developing such serious infections?

Staph Infections

These athletes were infected by Staphylococcus aureus, or “staph.” Staph is a common bacteria that most people carry on the surface of their skin and in their nose. To cause an infection, staph bacteria must get inside your body. The scrapes athletes commonly get provide an ideal entrance.

Serious problems due to staph infections used to be rare. Doctors would prescribe antibiotics, such as penicillin, to kill the staph bacteria. Ordinary staph infections can still be treated this way. The athletes in our examples did not have ordinary infections. These athletes’ scrapes were infected by methicillin-resistant Staphylococcus aureus (MRSA). This bacteria strain is one of many that has evolved resistance to antibiotics.

Drug-Resistant Bacteria

Bacteria that can survive antibiotic treatment are called drug-resistant bacteria. Some bacteria have resistance for one particular antibiotic, some have resistance for several, and a few cannot be treated with any known antibiotic.

MRSA can resist an entire class of antibiotics. Patients with an MRSA infection must often be treated with what doctors call “the drug of last resort,” vancomycin. Vancomycin is a drug that must be given intravenously. Not surprisingly, doctors began to see cases of vancomycin-resistant Staphylococcus aureus (VRSA) in 1997. By 2010, vancomycin-resistant bacteria were being discovered in the droppings of one out of ten seagulls, leading scientists to postulate that migrating birds may play a role in spreading drug-resistant “superbugs.”

Staph isn’t the only type of bacteria that is making a comeback with drug-resistant strains. In the mid-twentieth century, antibiotics nearly wiped out tuberculosis (TB). But in the 1990s, TB began to approach epidemic numbers again, and now it kills more than 2 million people every year. Drug-resistant TB kills thousands. Drug-resistant strains of cholera and bubonic plague also have been reported.

How Does Drug Resistance Evolve?

The incidence of MRSA infections is on the rise.

When you take antibiotics for a bacterial infection, billions of bacteria may be killed right away. However, a few likely survive. Antibiotics leave behind the more resistant bacteria to survive and reproduce. When they reproduce, the genes that make them resistant are passed on to their offspring. Some bacteria reproduce rapidly—E. coli, for example, doubles its population every 20 minutes.

In addition to their ability to reproduce quickly, populations of bacteria evolve rapidly. Bacteria use plasmids—small loops of DNA—to transfer genetic material between individual cells. This process is called conjugation. Some plasmids pass on resistance for one particular antibiotic. Others can transfer resistance for several antibiotics at once.

What characteristics do resistant bacteria pass on to their offspring? Some have cell membranes through which antibiotics cannot easily pass. Others have pumps that remove antibiotics once they enter the cell. Some can even produce enzymes that attack the antibiotic drugs themselves.

Fighting Back

Some scientists are trying to develop ways to treat patients without killing the bacteria that are making them sick. Instead, they target the toxins produced by bacteria. If the bacteria are not harmed by the treatment, no selective pressure is produced. Scientists hope that by using this approach, bacteria will be slower to evolve defense mechanisms against the antibiotics. Other scientists hope to fight back by using bacteria’s ancient rival, bacteriophages, which are viruses that infect bacteria.

Unanswered Questions

Some important research questions involving drug-resistant bacteria include the following:

  • Can plasmids or bacteriophages be used in vaccines to fight bacteria?
  • Are bacteria being exposed to antibiotics in sewage systems and evolving resistant strains there?
  • How do antibacterial soaps and household cleaners contribute to the evolution of drug-resistant
    bacteria?
  • Can drug-resistant bacteria be transferred from domestic animals to humans through food?

UPDATES: Straight from the Headlines

New Drug Delivery System

Researchers at Yeshiva University decided to take on one of the most difficult bacterial infections of all, methicillin-resistant staph. They have developed a treatment using nanoparticles that can be delivered directly to a wound on the skin.

  • Tiny nanoparticles carry nitric oxide (NO), which helps the immune system respond to infection.
  • The nanoparticles are applied topically, to deep, infected skin abscesses.
  • The nanoparticles absorb water, swell, and release NO. NO kills bacteria and dilates blood vessels, to speed healing.

Because the bacteria are “eating” the nanoballs, cell wall adaptations that once kept antibiotics out are no longer an obstacle.

Evolutionary Biologist in Action

Dr. Richard Lenski
Title: Professor, Microbial Ecology, Michigan State University
Education: Ph. D., Zoology, University of North Carolina, Chapel Hill

If you want to observe evolution in action, you must find populations that reproduce quickly. Dr. Richard Lenski, a professor at Michigan State University, has done just that. Dr. Lenski studies populations of E. coli bacteria, which he grows in flasks filled with a sugary broth. These bacteria produce about seven generations each day. Dr. Lenski has now observed more than 30,000 generations of E. coli.

The rapid rate of E. coli reproduction allows Dr. Lenski to watch evolution take place. Dr. Lenski can subject each generation of bacteria to the same environmental stresses, such as food shortages or antibiotics. He then can compare individuals from more recent generations with their ancestors, which he keeps in his laboratory freezer. By comparing generations in this way, Dr. Lenski can study how the population has evolved.

When Dr. Lenski began his research in 1988, watching evolution in action was still new. Now, many
evolutionary biologists are following in his footsteps.

Comments

  1. brandon says:

    love this article

  2. esmeralda says:

    group 5: Bryce, Gifti. Cristiana, Michael, Esmeralda
    When you take a antibotic it kills most of the Drug-Resistance Bacteria. The onces that survive go stronger and reproduce giving the offspring the resistance of the antibotic. To infect a person it first most get in your body.One type of staph dies and another better stronger one comes out. There are different types of bacteria that grow in different speeds. E.Coli is one of a fast growing bacteria that grows every 20 minutes. Bacteria evolve rapidly making more drug resistance bacteria so the antibotic can not kill them.

  3. devinkendrickshs says:

    makes me nerves to play football
    devinkendrickshs

  4. matthew cox says:

    The onces that survive go stronger and reproduce giving the offspring the resistance of the antibotic. To infect a person it first most get in your body. One type of staph dies and another better stronger one comes out. E.Coli is one of a fast growing bacteria that grows every 20 minutes.

  5. jordan valentine says:

    it makes me not want to play any contact sports anymore, because you will always get hurt and scabbed up.

  6. eduardo contla-flores says:

    can drugs resisted bacteria affected to animals than humans?

  7. ashleyperry says:

    Is there a certain way this can be treated

  8. sheridan gillett shs says:

    how can the bactera be cure

  9. katie w says:

    this article makes me worry because i am always gettin hurt and i dont want to go to the hospital and the doctor come in and say u wont be able to walk anymore

  10. Aerianna P SHS says:

    i think it is cool how they use antibiotics to treat bacteria. and i think that it is interesting how they are gonna find something that can treat things without killing any of the bacteria.

  11. Aerianna P SHS says:

    we need things to heal so our body dont get infected.

  12. China King says:

    This is a interesting article it talks about bacteria from injuries during sports and also injuries in general, and how some of the bacteria can be resistant to antibiotics that can be given to you to cure the infection. In my opinion it is nasty and i have not gotten an infection in an injury that has been resistant to antibiotics.

  13. Alyssa Scott says:

    Staph infections are disgusting ! They are the grossest things ever.

  14. ZinaRobinson says:

    This makes me not want to play football with the guys anymore. Or any sport at all that uses contact and falling. makes me wanna be more careful about playing games.

  15. kennedy says:

    what i thought bout this was that im doing no sports for me to catch something ooooh noooooooo

  16. Phatassia Babii Doll says:

    It makes me scared to play any sports now that i know this. I could get really hurt. I wouldnt know how to cure bacteria if their any way you could cure it.

  17. pwnpwn mcgee says:

    Well, this article is very very informative. I love it and I think it is a great resource for biologists anywhere!

  18. Makenzi Farr says:

    Its kinda scary that you can get into the hostpital over a scratch… thats too crazy..

  19. Tori says:

    I never knew about antibiotic resistant bacteria, though I figured not ALL bacteria or infections of that matter could be easily cured with antibiotics. I think it’s crazy that one little scrape can lead to a serious infection…who knew! I found it surprising that these drug-resistant bacteria can only be treated due to certain measures, and some cannot even be treated at all, causing these antibiotics to fail. I learned that the way that scientists are trying to go about curing this is by targeting the toxins produced by the bacteria, and not the bacteria itself. Others want to use bacteriophages to attack the bacteria. Over time, there is hope that the bacteria will slowly begin to not develop defenses against the antibiotics, causing them to be completely useless. ~Hi Bio Class! :)

  20. Chunky Kit Kat says:

    A serious infection just from scraping your knee in soccer or riding a bicycle? I never knew that such a thing could happen, especially since I’ve had those types of injuries before. The possibility that bacteria will eventually become immune to all antibiotics is, while good for bacteria, an unsettling thought for humans. Yet how bacteria gain their immunities make me want compare that process with how other species evolve and adapt to their surroundings. Ideas such as using plasmids or bacteriophages to combat drug-resistant bacteria really impress me for their creativity.

  21. Mr. Steal Yo Girl says:

    It is rather surprising that you could get infections just by little cuts. I myself always getting cut when i play sports never knew this could happen because it had never happened to me before. It is weird that bacteria is gaining immunities to these antibiotics but just like humans they too need to adapt to the environment to survive. Hopefully in the future they can stop evolving and they will eventually die out. Also thank you Ms. Lamas for giving me this wonderful assignment……….

  22. Becca says:

    What most surprised me about this article was that drug-resistant strands of tuberculosis, cholera, and the bubonic plague are on the rise. All of these diseases are infamous for killing loads of people, and it is very worrying that they’ve become a danger again.
    I knew about antibiotic-resistant diseases before reading this article. I learned that birds play a role in spreading antibiotic-resistant bacteria and about the new ways of fighting bacteria.

  23. Karina says:

    I never knew how dangerous a scratch could be and that staph infections could occur and be that serious. I knew that antibiotics would be able to cure infections. It is new to me that bacteria could build up resistance to the antibiotics. It is good to hear that scientists are working on antibiotics that can kill those bacterias. hopefully these bacteria stop building up immunity to the antibiotics.
    BIO ROCKS

  24. Lelo G balla says:

    Really good article about Bacteria! I didnt know there was more bacteria cells than humans cells in a human body!

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