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Daneeya Sheeraz
Jul 3, 20235 min read

From Wonder Drugs to Superbugs | Story About Antibiotics

Updated: Mar 23


Outline

The Mould in the Petri Dish

The journey from the development of antibiotics to bacterial resistance to antibiotics began in 1928 with the phenomenal discovery of the wonder drug, penicillin, by Alexander Fleming. This happened during a time when even a tiny scratch to the skin could become infected and prove fatal.


Image Credit: Science Museum

Fleming observed a Petri dish hosting a sample of Staphylococcus bacteria had a mould growing inside it. He noted that the bacteria was unable to grow on the mould, realising the mould was producing a chemical that stopped the bacteria from invading it. Said chemical was coined “penicillin” by Fleming and thus began the incredible road to curing scores of infections and production of multiple antibiotics. Many antibiotics that are now classified into many categories: penicillins, fluoroquinolones, cephalosporins, macrolides, beta-lactams, urinary anti-infectives, and tetracycline.


How do Antibiotics Work?

Antibiotics work by inhibiting important life processes in bacteria or damaging their cell structures. An example of antibiotics working by doing both the former and latter is penicillin.

Image Credit: BrainKart

It works by a process called lysis - the breakdown of a cell by damaging its cell membrane or wall. Bacterial cell walls are composed of peptidoglycan, and held together by cross-links. When bacteria are dividing into new cells by binary fission, they secrete enzymes, called autolysins, that create perforations in the cell wall to allow it to expand. However, penicillin works on growing bacteria by inhibiting the formation of these cross-links in the bacterial cell wall. This leads to autolysins further weakening the wall until eventually, uptake of water coupled with the fragility of the cell wall causes bacterial cells to burst open due to pressure.

Moreover, antibiotics only work to cure bacterial infections. Viral and fungal infections are unaffected by them. Furthermore, not all antibiotics can combat all bacterial infections. For example, penicillin may not work against bacteria with thick, impermeable cell walls or those able to produce enzymes that break down penicillin.

Bacterial Resistance to Antibiotics

Mutations in bacteria cause the development of antibiotic resistant bacteria, also called “superbugs". These strains cannot be treated with certain antibiotics and can be very difficult to treat. As usage and access to antibiotics increase, so do species of bacteria with immunity to these medications. Bacteria are particularly prone to developing resistance as they divide very rapidly: around every 4 to 20 minutes, depending on species.

More than 700,000 people die each year globally due to antibiotic resistant infections. In the United States alone, around 2.8 million of these infections are contracted annually, resulting in 35,000 deaths. Antibiotic resistant infections may result in lengthy infections, longer hospital stays, frequent visits to hospitals and costly treatments.

So what leads to the development of drug resistant bacteria? The main reason is misuse and overuse of antibiotics. This may include the following:

  • Using antibiotics for trivial infections that can resolve on their own.

  • Antibiotic usage for non-bacterial infections such as viral and fungal infections.

  • Frequent usage, prolonged use, self-medication and pressurising doctors into prescribing antibiotics.

The above reasons overexpose bacteria to antibiotics and give them greater opportunities to develop resistance. Antibiotics should also not be overused as they can cause many side-effects. Other reasons for antibiotic resistance developing include using the wrong antibiotic for an infection and not completing treatment courses as directed by a doctor. This allows some bacteria to survive and mutate.

Once bacteria have developed resistance to a certain antibiotic, they can pass this mutated gene on to other bacteria of their own species when reproducing by binary fission. This is called vertical transmission. They may also transfer this gene to other bacterial species by horizontal transmission. To do this, bacterial cells will join together by the pilus of the donor cell. Then, genetic information, often in the form of plasmids (circular DNA molecules), will be transferred to the recipient cell. This process is called conjugation and can allow more species of bacteria to develop resistance.



Image Credit: SlidePlayer

Proper usage of antibiotics can keep them effective for longer, reduce unfavourable side effects and reduce the spread of antibiotic resistant infections. Another way to reduce these harmful bacterial strains is to avoid contracting infections in the first place. This can be done by getting vaccinated, practising good hygiene, not consuming unclean water and unpasteurised milk, and cooking foods to a safe temperature (particularly meat and other animal products).


MRSA

Perhaps the most commonly known type of antibiotic resistant bacteria, MRSA (Methicillin-resistant Staphylococcus aureus), is resistant to several antibiotics. This makes it very hard to treat. Normally, it lives harmlessly on human skin. However, if allowed to enter the body, it may lead to critical infections, sepsis and death.

MRSA is common in hospital settings. Frequent hand washing and use of hand sanitizers can reduce the risk of spreading it, as uninfected individuals may still be carriers.

Skin infections due to MRSA present as boils or wounds that are painful, red and swollen, or secrete substances such as pus. Many other deadlier, harder to treat and more resistant bacteria such as Pseudomonas aeruginosa have also emerged.

Advancements and Alternative Methods of Treating Antibiotic Resistant Bacteria

Metal-based nanoparticles are natural minerals that have been used to treat infections for centuries. These may be elements such as gold or silver, or metal oxides such as copper oxide, titanium dioxide, zinc oxide and iron oxides. They may also be intermetallic nanoparticles made by combining metals. They are now being used to amplify the effects of antibiotics, or are used as substitutes where bacteria are resistant to antibiotics.

Two alternative methods of treating bacterial infections instead of using antibiotics are phage therapy (also known as phagotherapy or Viral Phage Therapy) and antivirulence drugs.

Phage therapy: bacterial infections are treated using bacteriophages (viruses that infect bacterial cells).

Antivirulence Drugs: This new type of drug is used to render bacterial cells harmless by attacking virulence factors (molecules that assist in bacterial colonisation of host cells) instead of destroying or killing the bacteria.

In conclusion, antibiotics are wonder drugs that have, since their discovery, altered medicine and made it easier to treat many illnesses. However, they are not without their cons and must be used with caution. Educating people and spreading awareness on the proper use of antibiotics is extremely important.


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