Most infections are caused by bacteria which have the ability to produce toxins that attack a host’s cell capability of fighting infections. These toxins are either endotoxins or exotoxins. Endotoxins act within the host’s cell by releasing enzymes while exotoxins are diffusible toxins which are released to act outside the bacteria cell (Todar, 2012). These toxins are secreted by the bacteria and are responsible for causing infections that damage the host’s tissues as well as attacking the immune system of the host.
Exotoxins are produced by a living gram negative and gram positive bacteria while lysed gram-negative bacteria produce endotoxins. Exotoxins act outside the bacteria cell while Endotoxins are part of the bacteria cell until the cell dies (Hayat, 2013). Exotoxins are made up of proteins while endotoxins are made up of lipopolysaccharides. Exotoxins are strong to immune reactions while endotoxins have weak immunity reactions (Min-Gang, 2014). Examples of endotoxins include E.coli (anaemia), salmonella typhi (typhoid) and shigella (shigellosis). Exotoxins examples include: Staphylococcus aureus (abcesses), Bacillus aureus (diarrhoea), Vibrio cholera (cholera) among others.
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Virulence factors are those factors that help increase the ability of an agent of infection to produce a disease. These virulence factors assist the bacteria to invade a host, causing diseases and weakening the host’s immunity to fight diseases. Most bacteria invade the mucosal sites where they adhere to the host’s cells while others are contained in capsules which keep them away from phagocytosis and opsonization (Cox, 2016). Siderophores are other factors that enable certain bacteria to create a competition for iron with a host which reduces iron content in the host creating chances of other iron-deficiency diseases
The ability of bacterial toxins to cause diseases in a host despite the resistance from the host is dependent on the number of the bacteria, the entry route into the host’s body and the defense mechanisms exhibited by the host. Hosts with weaker immunity create easier penetration of bacterial toxins which may keep on causing recurrent infections (Cox, 2016). Most toxins have coats which inhibit phagocytosis as well as receptors which they use to attach themselves to the host cells making it hard to eliminate them.
Bacterial toxins that are both the endotoxins and exotoxins have adaptive mechanisms which allow them to attach themselves to a host. They create an environment that renders the host immune system defenseless which allows these toxins to sustain their infection causing mission. It is, therefore, important for the hosts to ensure that their immune systems are capable of fighting these infections.
References
Cox, R. (2016). What are bacteria? OnHealth. Retrieved from http://www.onhealth.com/content/1/bacterial_infections.
Hayat, K. (2013). Difference between endotoxin and exotoxin. Medimoon . Retrieved from http://medimoon.com/2013/04/difference-between-endotoxin-and-exotoxin/.
Min-Gang, S. (2014). Incorporating amino acids composition and functional domains for identifying bacterial toxin proteins. BioMed Research International, Article ID 972692 .
Todar, K. (2012). Bacterial protein toxins. Retrieved from http://textbookofbacteriology.net/proteintoxins.html.
