THINK Project

ANtibiotics & Antibiotic Resistance

What You Should Know:

By: Elyssa Brown, Undergraduate StudentNorth Carolina State University Department of Biological SciencesDr. Lee, General Microbiology

What Are Antibiotics and How do They Work?

Antibiotics are medications used to treat a wide range of bacterial infections. There is bacteria in our bodies that are beneficial, such as the bacteria that aids in digestion and nutrient absorption in your gut and digestive system, and bacteria that helps maintain the barrier on your skin. However, there is also harmful bacteria that can cause diseases and infections like strep throat, staph infections, pneumonia, and many more. This is where antibiotics are important.

Antibiotics work in a number of ways. They either kill bacteria or stop them from growing and multiplying by blocking vital processes in bacterial cells, such as targeting the cell wall or protein synthesis. Antibiotics that kill bacteria directly are known as bactericidal, and antibiotics that inhibit the growth of bacteria are known as bacteriostatic. Different antibiotics target different parts of the cells.

Interested in the details of how antibiotics work?

Most antibiotics can be placed into one of six classes. Learn more about the classes of antibiotics!

Types of Antibiotics

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Penicillins

2

Cephalosporins

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Aminoglycosides

4

Tetracyclines

5

Macrolides

6

Fluoroquinolones

What is Antibiotic Resistance?

Bacteria can develop defences against antibiotics, which is called antibiotic resistance. Antibiotic resistance causes medications to become ineffective in treating bacterial infections as they are no longer able to kill the bacteria or stop them from multiplying. Watch this video to see antibiotic resistance explained.

How Does Antibiotic Resistance Happen?

Antibiotic resistance will occur naturally due to natural selection, but the misuse and overuse of antibiotics also speed up the process. Frequent exposure to antibiotics encourages the bacteria to develop a way to survive. Once a resistance gene is added to a bacterial cell’s DNA, the bacterium can pass the resistance gene on.

Natural Selection

Rapid Reproduction

Mutations

DNA Exchange

When bacteria are exposed to an antibiotic, the bacterial cells that are the most susceptible to the antibiotic die quickly. The bacteria that survive pass on their resistant genes in order to allow more bacteria to survive against the antibiotic.

Mutations occur randomly, some which are harmful to the bacteria and some which are useless, some mutations give bacteria and advantage in survival, such as becoming resistant to an antibiotic.

Bacteria reproduce rapidly, which allows them to pass on their resistant genes, and quickly create a larger bacterial population that is resistant.

Reproduction is not the only way for bacteria to share genetic information.Conjugation allows bacteria to share their genes through connecting pili. There are multiple ways of passing DNA to other bacterial cells they come in contact with.

Fun & Games!

Click here to play a word search puzzle!

Click here to play game: Agent Antibiotic!

Why is Antibiotic Resistance Important?

When bacteria become resistant to antibiotics, it makes bacterial infections harder, and in some cases impossible, to treat. This can mean that eventually, a disease or infection that was at one point easily treatable, can become fatal, reaching a point where there is no treatment. Bacterial strains that are resistant to multiple antibiotics are known as superbugs. Some examples of superbugs include:

• Methicillin-resistant Staphylococcus aureus (MRSA)
• Vancomycin-resistant Enterococci (VRE)
• Clostridium difficile (C. diff)
• Multi-drug-resistant Mycobacterium tuberculosis (MDR-TB)
• Campylobacter

Click here to learn what you can do to help prevent and avoid antibiotic resistance.

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Aminoglycosides work by binding to ribosomal RNA inside the bacterial cell, causing a misreading of transfer RNA codons, resulting in the formation of incorrect proteins. They can be used to treat infections such as endocarditis, sepsis, and tuberculosis.

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Fluoroquinolones work by inhibiting bacterial enzymes, DNA gyrase and topoisomerase IV, which are invovled in DNA replication, effectively stopping the bacteria from multiplying. They can be used to treat infections such as septicemia, joint and bone infections, and pelvic inflammatory disease.

4

Tetracyclines work by binding to the ribosome, inhibiting translation within the bacterial cell, which blocks protein synthesis, and stops the bacteria from growing and spreading. They can be used to treat infections such as syphilis, staph infections, and acne.

1

Penicillins work by inhibiting the cross-linking of peptidoglycan within the cell wall, causing damage that destroys the bacteria. They can be used to treat a wide variety of infections such as strep throat, ear infections, and urinary tract infections.

2

Cephalosporins kill bacteria by preventing them from forming cell walls. They can be used to treat infections such as meningitis, skin or soft tissue infections, and pneumonia.

5

Macrolides work by binding to the 50S ribosomal subunit in bacteria, preventing protein synthesis which stops the bacteria from growing and multiplying. They can be used to treat infections such as tonsillitis, rhinosinusitis, and pneumonia.