Aaaaaachooo..!! And this initiates the dreaded period of coughing, blocked nose, headaches, fatigue and obviously days off work (which we don’t really mind).Usually, in this situation most of us would go to the doctor, who will then prescribe us with antibiotics such as penicillin or amoxicillin. So we go home take the dosage and in couple of days we start to feel better.
What do we do next? I am sure we have all been guilty of partially finishing our antibiotics course and leaving few tablets behind, thinking that we have been cured. But only if we knew how mischievous bacteria were you would always finish your prescribed dose.
What are bacteria?
Bacteria are unicellular (single-celled) microorganisms, typically a few micrometers in length. They have a number shapes, ranging from spheres, to rods to spirals and are known to be one of the first life forms on Earth inhabiting a range of habitats such as soil, water, acidic hot springs etc (Figure 1). Bacteria were first observed by the Dutch microscopist Antonie van Leeuwenhoek in 1676, where he used a self-designed single-lens microscope. In 1828, Christian Gottfried Ehrenberg introduced the word “bacterium”.
We are surrounded by these microorganisms, in fact the human microbiome comprises of 100 trillion bacterial cells; most of them inhabiting our gut. Bacteria can be categorised into two categories i.e. good bacteria and bad bacteria. Our microbiome comprises of good bacteria that help with our digestion and over all well being but it’s the bad bacteria that cause us discomfort and make us fall ill.
Figure 1: Rod shaped bacteria (Ref: https://www.popularmechanics.com/science/health/news/a27889/99-percent-bacteria-humans-unknown/).
What makes the bacteria bad?
Bacteria are very cunning and I say this because these organisms comprise of various mechanisms to deceive you in thinking that your incomplete antibiotics course has cured you. Bad bacteria are known to form a parasitic association with other organisms; hence they are also referred as pathogenic bacteria. Pathogenic bacteria are a major cause of human death and disease and can cause infections such as tetanus, typhoid fever, diphtheria, food poisoning or as simple as the common cold. Some of these bacteria include Salmonella, E.coli, and Staphylococcus etc. Due the simplicity of these microorganisms bacteria have the advantage of growing at an exponential rate, under optimal conditions e.g. E.Coli cells divides into two every two minutes! Being unicellular, bacteria grow to a fixed size and reproduce through binary fission, which is a form of asexual reproduction. During cell division, the bacterial cells divides in two identical clone daughter cells and can double the population as quickly as every 9.8 minutes (Figure 2).
Figure 2: Mechanism of Binary Fission (Ref: http://ucsdnews.ucsd.edu/archive/newsrel/health/08-08FleshEatingBacteria.asp).
Mechanism of infection
When bacteria come in contact with their host, they start to multiply within the host’s body. Disease usually occurs when the cells in our bodies are damaged. In response to such an invasion our immune system get activated to fight off the foreign invader, during this time the host may experience symptoms like fever, rash, headache, malaise etc – which is a result of the immune system fighting against the foreign invader. Bacteria have various mechanisms to make us sick such as; multiplying rapidly and causing crowding in the host tissue; disrupting normal function, releasing toxins to paralyze, destroy cells’ metabolic machinery or induce a massive immune response that is toxic (Figure 3).
Figure 3: Flesh eating bacteria attacking the host (Ref: http://www.justscience.in/articles/what-is-binary-fission/2017/06/22).
Formation of SUPERBUGS
Since now we are familiar with what bacteria are and how they can cause infection, let’s address the actual issue: How can bacteria deceive your body in thinking you are cured, even after you haven’t completed your recommended antibiotics course? The answer lies in the genetics of bacteria and how they can mutate to gain antibiotic resistance, in turn leading to the formation of superbugs.
Bacterial genetics is fairly simple, where most bacteria carry a single circular molecule of DNA, which encodes for the genes essential for reproduction and other cellular functions. These microorganisms are also known to carry accessory small rings of DNA, known as plasmids, which encode for specialised functions like antibiotic resistance (Figure 4). Considering the rate at which bacteria replicate it is common for mutation to occur within the population, hence causing some variation. Sometimes bacteria exchange plasmids amongst one another in a process called conjugation, hence through this mechanism bacteria can pass on antibiotic resistance property from one cell to another.
So when we think that we have been cured after a few doses of the antibiotics and decide to stop, we give the mutated bacteria the opportunity to thrive in our bodies and replicate. This leads to some strains of bacteria to be resistance to all the antibiotics e.g. MRSA, leading to severe infection and then death.
Figure 4: The process of conjugation to gain antibiotic resistance (Ref: http://euarch.blogspot.co.nz/2007/09/conjugation.html).
Currently antibiotic resistance is one of the biggest issues in medical science, as scientists cannot produce antibiotics at the rate at which bacteria are mutating and forming into superbugs. The increase in antibiotic resistance is a result of human ignorance, so next time bear in mind that stopping your medication ahead of time doesn’t cure you but makes you the creator of superbugs. By being ignorant, you might be pushing mankind towards a world without antibiotics.
About The Author
Shalini Guleria is currently pursuing her Masters in Tissue Engineering where her research is focused on developing better treatment and detection techniques for Cancer. She is presently associated with Scion Research, New Zealand and holds a Bachelor's Degree in Chemical and Biological Engineering from the University of Waikato, New Zealand. Shalini has won two consecutive national awards at the prestigious Sir Paul Callaghan Eureka Awards for engineers and scientists. Apart from sciences, she is also a highly talented artist.