Bacterium And Disease

There are many bacteria that cause disease.

There are several types of organisms that can cause infectious diseases. Most are microorganisms. Several types of multi-cellular organisms can also cause the infection.

Bacteria are microorganisms that are plantlike in some characteristics. A bacterium is a tiny, primitive cell without a nucleus Bacterial cells has cell walls as do plant cells. Some bacteria, such as those that live in the intestines, are beneficial to human beings. Others cause disease. Most harmful bacteria do not invade cells. Instead, they grow on surfaces or between cells. They are microscopic, a single-celled form that is able to carry on all the processes of life.

Bacteria are found nearly everywhere, in the air, in the water, and in the earth. Certain conditions, however, are necessary for their growth and reproduction. They must have the proper nourishment, temperature, moisture, salts, chemicals and an absence of sunlight. Some gain their nourishment from lifeless organic matter, and others are parasitic, living on the tissues of the plant or animal body. Most bacteria are helpful as they destroy and disintegrate dead organisms, both plant and animal. Others transform chemical elements such as carbon and nitrogen into forms that can be used by plants.

Living organisms called pathogens cause infectious diseases. One group of pathogens is the bacteria. Bacteria produce disease in a variety of ways. They can secrete toxic substances that damage human tissues, they may become parasites inside human cells, or they may form colonies in the body that disrupt the normal human function. Poisonous substances released by pathogens into the body's system are called toxins. These toxins upset body functions. Infection tends to follow a definite pattern in the body. As a result of infection, tissues become red, hot, swollen, and painful. Cells are destroyed. Symptoms such as fever, rash, nausea, and diarrhea frequently indicate the infection. Like viruses, bacteria are also a divorce group of pathogens ("disease-producers"). There are several ways to classify bacteria:

1. Function- For example, bacteria are categorized as aerobic (requiring oxygen for their metabolism) or anaerobes (requiring an absence of oxygen).

2. Staining properties- Different bacteria stain differently, depending on the compounds in their walls. For example, gram-positive bacteria are stained purple by Gram's staining technique, whereas gram-negative bacteria are not.

3. Shape and size- Bacteria are most commonly classified by their varied shaped. Medically significant bacteria range in size from 0.5 um to more than 5 um, making size a useful characteristic for classification. (The um represents micrometers or microns, one-millionth of a meter). Some major groups based on shape and sizes follow:

A. Bacilli (ba-SIL-eye) - These are large, rod-shaped cells found singly or in groups.

B. Cocci (KOKS-eye) - These large, round bacteria are found single, in pairs (diplococci), in strings (streptococci) or in clusters (staphylococci).



C. Curved or spiral rods - These can be curved rods arranged singly or in strands, or they can be large curved or spiral cells or cell colonies.

D. Small bacteria - These round or oval bacteria are so small that some of them were once thought to be viruses. They can only reproduce inside other living cells, so they are sometimes called obligate parasites. Rickettsia (ri-KET-see-ah) and Chlamydia (kla-MID-ee-ah) are two types of small bacteria.

There are only a relatively small number of bacteria that are harmful to man, no more than five per cent. These pathogenic bacteria, when introduced into animal or plant tissues, product certain changes or characteristics that we associate with the symptoms of disease. Pathogenic bacteria attack the tissues by secreting ferments that decomposes the material on which the bacteria live. This decomposition, plus the waste product from the bacteria damages the tissue cells. Bacteria also give off toxic substances that intensify their mischief.

The manner in which bacteria can harm the body varies as some bacteria produce gases that harm the tissue by pressure; gas gangrene is an example. Bacteria produces soluble toxins that absorb into the body, and give the characteristic symptoms of the disease, whether the germs responsible are present. Examples are the germs of diphtheria and tetanus (blood poisoning). Some pathogenic bacteria become so numerous as to congest the region where they are found. The germs of anthrax and whooping cough are examples. Most bacteria, when broken down by the body's protective agencies, give off insoluble toxins.

Some pathogenic bacteria are not visible. Ultra-microscopic in form they can be responsible for influenza, foot-and-mouth disease, smallpox and measles. The pathogenic bacteria readily pass through a Berkefeld filte. These small pores allow only the invisible forms of bacteria to pass through. These small forms are called filterable viruses. Their presence is detected through changes they produce in media from which all other bacteria have been removed by filtration. These have the power of growth and reproduction, but their actual structure is a matter of conjecture.

The Rickettsiea are pathogenic microorganisms that have much in common with the viruses, but are transmitted from host to host by insect or arthropod vectors. These can be seen with the light microscope. They are propagated in living cells. Epidemic typhus fever (by lice) is caused by this microorganism. It is possible to give vaccines against typhus fever and Rocky Mountain spotted fever caused by wood ticks.

It is necessary to mention how these disease bacteria are spread as there are several routes by which they gain entrance, thus complicating their control. There are three main ways that microorganisms cause disease to spread. Inanimate objects, like dust, soil, food, water, air, drinking cups, and towels, which pass on to the individual, spread infection. Examples of the indirect contact method of obtaining pathogenic disease through the spread of bacteria are cholera, dysentery and tuberculosis. Infection spreads by direct contact between infected persons by bodily contact, such as handshaking, coughing, sneezing, and kissing. This direct contact will cause common diseases such as measles, scarlet fever, colds, pneumonia, etc.

The last method of transmission occurs through some intermediate agency like an insect or some other animal or person. Mosquitoes spread malaria and yellow fever. Flies are responsible for body lice, typhus fever, and typhoid fever.

There are ways to control some pathogenic bacteria. Once a pathogenic bacteria and infection occurs in an individual, it may spread to other regions, increasing the severity of disease. It spreads directly through the tissue, the blood stream, the lymphatic system and the nerves. Bacteria will thrive best at a particular optimum temperature and in pathogenic the optimum temperature is that of body temperature of 37 degrees C. Most forms, especially the ones without spore producing capability are destroyed at sixty degrees C and above. One of the best methods of destroying bacteria is by sterilization with heat, either dry or moist. Dry is another method of killing bacteria as moisture is necessary for growth. Bacteria seem to thrive in the dark, or a diffused light and the ultraviolet rays of the sun are helpful in killing them.

The best defense against pathogenic bacteria is keeping the body healthy to resistance some diseases. Seek medical attention and follow your doctor's orders faithfully. Isolate yourself from giving the disease bacteria to others. Some pathogenic bacteria will cause chronic disease. The condition often worsens as time goes on. In many such diseases the effects are lifelong.

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