Pathogen Evolution and Antibiotic Resistance

whats the point?

By the end of this lesson, you will understand which pathogen is making the Thompsons sick, how bacteria (and other pathogens) have evolved, what antibiotic resistance is, and how it affects us.

Homeostasis

As we continue learning about the immune system, we must grasp the idea of homeostasis—the body’s capacity to maintain internal equilibrium despite external fluctuations. A vital aspect of this balance is the immune system’s role in fighting off pathogens while preserving the body’s internal stability.

homeostasis is the body’s capacity to maintain internal equilibrium despite external fluctuations.

When homeostasis is disrupted, particularly in the immune system, it can lead to significant health challenges. This disruption can manifest as either an overreaction or an underreaction of the immune response. Overreactions can trigger autoimmune diseases, where the body attacks its cells, mistakenly identifying them as threats.

Conversely, an underactive immune response can leave the body vulnerable to frequent and severe infections, illustrating the critical balance the immune system must maintain to protect the body effectively without causing harm.

The Thompson Family is STILL sick!

Despite initial treatments, the Thompsons were not feeling better, prompting them to visit their doctor for further testing.

Their test results are in, and we were hoping you could determine what the doctor’s office has concluded!

Before we move forward, we need you to identify the type of pathogen responsible and explore why it might be resistant to conventional antibiotics.

The Lab Results

So here they are. Open them up and take a look. Do you see a pathogen they might all have in common?

Quick Check!

The Culprit...Bacteria!

Pathogens such as bacteria, viruses, and fungi are in a constant state of evolution. For bacteria, mutations during DNA replication or acquiring genes from other bacteria through horizontal gene transfer are common evolutionary tactics. These adaptations can provide survival benefits, such as resistance to antibiotics. Viruses evolve quickly because they have high mutation rates and can recombine their genetic material, leading to new, sometimes more dangerous, strains.

Let’s focus more on bacteria and their treatment, such as antibiotics.

We have all most likely taken an antibiotic at some point in our lives. Did you take it as directed by your doctor and pharmacy? Did you finish the entire prescription or only take it until you felt better?

Antibiotic resistance occurs when bacteria develop the ability to defeat the drugs designed to kill them.

This resistance means that bacteria are not destroyed and continue to grow and spread. This phenomenon can occur naturally but is often accelerated by human actions, mainly through the misuse and overuse of antibiotics. As bacteria become resistant, standard treatments become ineffective, infections persist, and they may spread to others, increasing the risk of severe disease, complications, and mortality.

The emergence of antibiotic resistance primarily stems from the misuse and overuse of antibiotics in different areas. For example, when antibiotics are prescribed for viral infections like colds or the flu—conditions unaffected by antibiotics—it can inadvertently lead to bacteria developing resistance. In agriculture, antibiotics are frequently used to treat ill animals, promote growth, and prevent diseases in healthy livestock, exacerbating the problem.

Also, some bacteria survive when patients don’t complete their prescribed antibiotic treatments. These surviving bacteria can adapt and build resilience, making future infections tougher to treat. Inadequate infection control in healthcare settings can also contribute, as it may facilitate the spread of resistant bacteria among patients.

Antibiotic Resistance is Legit!

Addressing antibiotic resistance requires a collaborative, multi-layered strategy.

One effective approach is establishing stewardship programs in healthcare, ensuring antibiotics are prescribed only when needed and in proper doses, thus reducing unnecessary exposure that drives resistance.
Governments play a vital role by enforcing stringent antibiotic use guidelines in medicine and agriculture, limiting opportunities for resistance to develop.
Educating the public is also essential; raising awareness about the importance of following antibiotic instructions and avoiding misuse can help lower unnecessary demand.
Investment in research is equally important, as creating new antibiotics and alternative treatments, such as bacteriophage therapy or vaccines, is necessary to keep pace with resistant bacteria.
Lastly, as antibiotic resistance is a worldwide concern, international collaboration is critical to effectively monitoring, managing, and responding to resistance trends.

Through a comprehensive approach, the threat of antibiotic resistance can be more effectively controlled and minimized.

Super Bacteria

Several bacteria have developed antibiotic resistance, creating serious challenges in treating infections.

A commonly known bacteria, Methicillin-resistant Staphylococcus aureus (MRSA), often found in hospitals and community settings, resists beta-lactam antibiotics like methicillin, leading to hard-to-treat skin, blood, and lung infections.
Vancomycin-resistant enterococci (VRE), common in hospitalized patients, resists vancomycin and penicillin and causes infections in wounds and the urinary tract.
Multi-drug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii can survive on hospital surfaces, resisting carbapenems, fluoroquinolones, and aminoglycosides, causing pneumonia, bloodstream infections, and wound infections.
Drug-resistant Neisseria gonorrhoeae, increasingly resistant to ceftriaxone and azithromycin, threaten the treatment of gonorrhea.
Finally, Clostridioides difficile (C. diff), often resistant to fluoroquinolones, proliferates when antibiotics disrupt normal gut flora, causing severe diarrhea and colitis.

These resistant pathogens underscore the need for stringent antibiotic stewardship, new drug research, and infection control measures.

That's the point

The misuse of antibiotics has led to antibiotic resistance, a serious public health issue that requires everyone—individuals, healthcare workers, and policymakers—to work together. By understanding how germs change and cause resistance, we see the importance of responsible antibiotic use.

►Next Up: In the next lesson, we will explore the epidemiology triangle, which explains how the host, agent, and environment interact to cause disease outbreaks. Now that we know what is making the Thompsons sick, we need to figure out the exact pathogen of the epidemiology triangle to stop the spread of this pathogen!

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