Types of Microbiological Organisms that Cause Disease

A microorganism is a living organism and they can only be seen through a microscope.

Bacteria

Bacteria cells are prokaryotic cells (single celled organisms). Bacteria cells have a variety of different organelles including a single circular strand of DNA, plasmids (small rings of DNA), a cytoplasm, a cell membrane and a cell wall. Furthermore, as a single celled organism, bacteria often have other adaptations such as a flagellum (a tail for movement) or specially shaped. Bacteria cells are found almost everywhere. Some are pathogenic (bacteria that cause disease). Pathogenic bacteria release harmful toxins into the body. However, others are completely harmless (known as flora) and undertake a required function in the body. One example of non-pathogenic bacteria in the human body is the 300 to 500 different types of bacteria in the gut. This aids in both the digestive system and immune system. For instance there is Bacteroides fragilis which is always present in the guts. In terms of the reproduction of bacteria, they reproduce through binary fusion. This process involves bacteria dividing into two. These then divide again to make four. This process then occurs again creating a cycle. For bacteria to grow, they need to have the optimal temperature and PH, alongside, nutrients, water and sometimes oxygen. In terms of temperature, the ideal temperature depends on the type of bacteria but, for optimal growth, bacteria need to be warm. At 0 – 5 C, bacteria tend to grow more slowly and at -18C bacteria become dormant (inactive). In addition, most bacteria, grow best at a neutral PH but some, thrive in particularly acidic or alkaline conditions. Oxygen is only needed for aerobic bacteria.

One example of an opportunistic infection is Tuberculosis (TB) which is a pathogenic disease caused by bacteria. This condition affects the lungs and is caused by tuberculosis Mycobacterium. Through inhaling contaminated droplets from an infected person, TB is spread. There are a variety of signs and symptoms which tend to develop slowly. These include, a cough that last over 3 weeks which may bring up phlegm and blood, Pyrexia (raised body temperature), weight loss, night sweats and swollen lymph nodes. Typically, in healthy people, the body’s defense system kills the bacteria and as a result, there are no symptoms. However, in the case of active TB, antibiotics are used for 6 months and sometimes hospital treatment is required. It can almost always be treated. Finally, there is also a BCG vaccine that is given to at risk areas and vulnerable groups such as, health and social care practitioners.

Virus

Viruses, the smallest of all microorganisms, duplicate by fastening on to a host cell and getting inside it. The virus then instructs the cell to create copies. At some point, the cell will burst, causing the virus to enter new host cells and reproduce. This can occur in just a few hours. Each time, the virus reproduces, the DNA is altered slightly making it, overtime, unrecognizable to the body. This is why the human body can catch a common cold more than once and vaccines can become ineffective. All Viruses are simple organisms that contain a strand of genetic material and a protein coat. For growth, microorganisms must have water along with mineral elements and gas, such as, oxygen. Microorganisms also need the correct conditions and, In terms of temperature, most viruses thrive in colder temperatures which is why cases of influenza increase during the winter. Most viruses do, however, become deactivated between 74C - 100C.For instance, one example of a virus is influenza that is a common condition with similar but, more long lasting and severe, symptoms to a common cold. Influenza is spread through tiny droplets expelled from coughing and sneezing. These droplets can settle on surfaces and then be picked up from contaminated surfaces. The symptoms involve high temperature, tiredness, weakness and general aches and pains. To prevent the spread of influenza, vaccinations are available but must be given annually. Furthermore, once infected, over the counter painkillers (such as paracetamol and ibuprofen) can be used to manage symptoms.

Fungi

Fungi are single celled or complex multicellular organisms. They live on dead and living cells that cause irritation. In terms of structure, the body of fungi is called a mycelium with fine threads called hyphae. The hyphae release digestive enzymes that absorb the nutrients (essential for growth). These hyphae branches grow into the air and are known as aerial branches. Spores then grow onto the hyphae and allow the spores to reproduce. The hyphae can penetrate the human skin and help to spread the fungi. In terms of requirement for growth, fungi grow best between a PH of 4.8 and 7 and have an optimum temperature of 30C. One example, of a fungal infection is athlete’s foot which usually appears between the toes. It can be for instance, spread through touching infected skin or touching contaminated surfaces. In the case of athlete’s foot, the skin may become, red, blistered, itchy, dry and cracked. There are various different prevention methods which involve good hygiene methods such as drying your feet properly especially, between the toes, wear clean cotton socks, use a separate towel for your feet and avoid sharing socks, towels and shoes. In terms of treatment, once infected, you can buy antifungal creams from a pharmacist.

Protozoa

Protozoa are more complex eukaryotic microorganisms and they have a variety of different organelles. In terms of reproduction, most reproduce asexually (but some reproduce sexually) through binary fusion. Additionally, protozoa live in a variety of moist habitats including soil and freshwater. This is because, for growth, protozoa require water for both, taking in oxygen through the cell membrane and taking in nutrients. Most protozoans reproduce best at 20C but it can be anywhere between 18-25C. The protozoa are most significantly known for their independent movement which is what divides the species onto four types including Amoebas, Flagellates, Ciliates and Sporozoans. One example of a protozoa that causes disease is a Plasmodium that causes malaria. There are 4 different species and they are found in more than 100 countries including large areas of Africa, Asia and South America. It is spread from the bite of an infected mosquito. The signs and symptoms of malaria involve high temperature, sweats and chills, vomiting and diarrhea and muscle pains.