Pathogenic and nonpathogenic microorganisms: characteristics and selection

Pathogenic & Nonpathogenic

Microorganisms have the capacity of causing severe disease if the conditions are ideal enough to sustain the life of these microbes. As more and more microbes are able to grow, the risk of disease development rises. Although all microorganisms have the capability of producing virulent effects, some are more able to do so than others. Pathogenic microorganisms are strong enough to fight off the natural defenses of the human body and are therefore almost guaranteed to cause some sort of disease (Murray & Rosenthal, 2008). On the other hand, non-pathogenic microorganisms or opportunistic microorganisms are only able to cause disease if the body's natural defense system is compromised through either an illness such as HIV, or through the taking of medications that may temporarily suppress the immune system (Murray & Rosenthal, 2008). All types of microorganisms need to be in their ideal growth environment, or ecological niche, in order to properly thrive and produce their effects. If these microbes enter an area outside of their ecological niche, they can either be deprived of the nutrients necessary to grow, or may in fact encounter an environment that could cause them to grow out of control.

Clostridium botulinum is an example of a pathogenic microorganism. These bacteria are the cause of the severe disease that causes flaccidity and paralysis of the muscles known as botulism. These same bacteria however, are used in very small doses as the main ingredient in botox, a procedure widely used to reduce the appearance of wrinkles on people (Murray & Rosenthal, 2008). This bacterium is a gram positive, rod-shaped, spore-forming, obligate anaerobe (Murray & Baron, 2011). In order for the bacteria to be able to reproduce and cause their pathogenic effects, oxygen cannot be present, as it will hinder their metabolic process. The presence of the bacteria themselves is not the sole cause of pathogenesis in mammals, but it is the neurotoxins that they produce as a waste product during metabolism, that make these pathogenic microorganisms so dangerous (Murray & Rosenthal, 2008).

Clostridium botulinum needs to be in a proper environment in order to grow, reproduce, and cause disease. Originally, this bacterium was isolated from hams and sausages that had been improperly persevered (Murray & Baron, 2011). Because it is an obligate anaerobe, it requires for no oxygen to be present in order for it to grow. Its ecological niche is one where oxygen is minimized. These bacteria's survival depends on their ability to form spores, a condition that is only achievable under anaerobic conditions (Murray & Baron, 2008). Although a small amount of oxygen will not immediately hinder their growth, long enough exposure will. As conditions start to deteriorate in their ecological niche, that is the increase in the presence of oxygen, they start to form spores in order to assure their survival. The fact that these spores form, create an extra barrier for the killing of these bacteria, making them extremely pathogenic.

As previously stated, not all bacteria or microorganisms are necessarily a cause for concern, such as opportunistic microorganisms. Staphylococcus aureus is an example of non-pathogenic bacteria. These bacteria are gram positive, ball shaped, clustered, facultative anaerobes (Murray & Baron, 2011). They prefer the presence of oxygen in order to successfully grow, but are also able to do so successfully in its absence. These bacteria naturally grow on and in the human body and are always present. Because of the products that these bacteria produce during metabolism and essentially as a waste product, they are able to fend of other disease-causing bacteria that may come in contact with the human body (Murray & Rosenthal, 2008). They act in support of the body's natural defense system. However, once this defense system is lowered or compromised, Staphylococcus aureus are able to grow out of control, gaining the capacity of causing illness and disease.

The environment that Staphylococcus aureus is able to successfully grow in, impact its ability to become virulent forces. As previously stated, these bacteria's ecological niche is the human body; they have a commensal relationship with the body (Murray & Baron, 2011). By stating this, it is implied that the body provides the nutrients necessary for these bacteria to survive, while the bacteria provide the body with protection by keeping other bacteria on the body at bay by competing for nutritional resources; they secrete toxins that will not allow other potentially pathogenic bacteria to survive. However, if the body's immune system were to be compromised, Staphylococcus aureus will continuously reproduce and start to shut off the naturally produced antibodies that help maintain these bacteria under growth control (Murray & Rosenthal, 2008). This is the leading cause of skin diseases such as atopic dermatitis and respiratory illnesses.

As aforementioned, all microorganisms carry the capacity to cause disease in individuals. However, Clostridium botulinum and Staphylococcus aureus are both examples of bacteria that can cause harm to the body under varying conditions. Staphylococcus aureus is naturally accepted by the body and can come in contact with the body systems without necessarily causing them any harm. Under normal conditions, these bacteria will do absolutely nothing, unlike Clostridium botulinum (Murray & Rosenthal, 2008). Clostridium botulinum is virulent and will therefore inevitably cause disease in the body. Because of the strength of these bacteria and their ability to form spores, which Staphylococcus aureus is unable to do, they are able to survive harsher conditions that would otherwise kill other microorganisms off.