One of the typical causes of illnesses in humans is germs. And when one says the term ‘germs’, they either mean bacteria, viruses, fungi, protozoa or helminths. Of these infectious agents, among the most common cause of severe illnesses in humans is bacteria. They are really, tiny microorganisms that are visible only using the aid of a microscope. This makes us wonder how does bacteria cause illnesses in humans? These tiny microorganisms have a certain pathway that leads to development of an infection in an otherwise healthy person. Let us go into the details of how does bacteria trigger diseases in this Buzzle article.

What Makes Bacteria Pathogenic?

Bacteria are referred to as pathogens as they are able to trigger a illness in plants, insects, animals at the same time as humans. The capacity of a bacteria to trigger illness is referred to as as pathogenicity. This pathogenicity is expressed in terms of virulence. This means the degree of pathogenicity a specific organism exhibits. There are some determinants of virulence that give bacteria its capacity to trigger a illness. These determinants of virulence can either be a genetic code, biochemical pathway or structural feature. Let us have a examine the factors that makes a bacteria pathogenic:

☛ Fimbriae
The fimbriae, (also referred to as pili) are hair-like structures present on the surface of the bacteria body. These fimbriae aid the bacteria to attach themselves to specific websites within the body. This helps prevent the bacteria from start washed away by body fluids. Fimbriae are commonly seen in most of the enterobacteria, like E.coli. These bacteria usually trigger urinary tract infections. Thus, the pili prevents the bacteria from being washed away from the bladder by means of urine.

☛ Flagella
Flagella are long tail-like structures that help the bacteria swim or move. These flagella aid the bacteria migrate to its site of infection and survive. Thus, flagella in this way helps boost bacterial pathogenicity.

☛ Toxins
Bacteria produces toxic compounds that cause harmful effects on the body. These compounds are nothing but toxins that trigger vomiting and diarrhea. These toxins are quite dangerous and can even induce severe discomfort, high fever as well as result in paralysis. Most bacteria are completely harmless, if they fail to generate toxins. Among the classical examples where toxins are commonly noticed is within the case of bacteria that trigger food poisoning.

☛ Invasion
Some bacteria have the ability to invade the body cells and trigger pathogenicity. Some bacteria destroy the cells as they feed on the cellular content. As an example, Salmonella typhimurium has the ability to destroy intestinal cells and trigger severe diarrhea. One of the chronic illnesses caused due to invasion is tuberculosis. The Mycobacterium tuberculosis invades the cells of the lungs and destroys the cells.

However, not all bacteria are able to cause illness in humans. Though they’re pathogenic in nature, the body’s natural defense prevents them from doing any harm. Thus, only if the bacteria is smart enough to hide, evade or fight back the immune reactions of the body, it is going to be able to trigger illness. Let us now have a examine the strategies undertaken by bacteria to trigger illnesses in humans.

How Does Bacterial Invasion Lead to an Infection?

Before we go into the details of how does bacteria trigger diseases, it is essential to understand the distinction between ‘infection’ and ‘infectious disease’. When an organism is in a position to lodge itself in or the tissue of the host and multiply, it’s called as an infection. Nonetheless, not every infection leads to a illness. The immune system acts swiftly and curbs the development of illness. When a illness may be transferred from an infected individual to a healthy individual, resulting in a illness, it’s termed as an infectious disease. So, how does one get infected with an infectious agent?

Mode of Infection
In order to cause disease in humans, the bacteria 1st has to break the barriers of the skin and tissues. Only right after it gets entry into the body, a bacteria can cause illness. You will find different modes of transmission of bacteria as follows:

☛ Contact
When an infection spreads by way of direct or indirect contact, it might lead to an infection. As a way to differentiate between direct and indirect transmissions, the term contagious disease is utilized to specify a disease that’s caused by direct contact. Infectious disease is a term which is generally utilized to specify diseases spread by other modes. Therefore, sexually transmitted illnesses are examples of infections spread by direct contact. Infections spread by contact with infected objects like pencils, glasses, towels, toys, etc. are termed as indirect infections like in the case of diphtheria.

☛ Inhalation
Most of the respiratory infections are spread by way of inhalation of the infectious bacteria. These bacteria tend to be present in air in type of aerosols. They’re released inside the environment by sneezing, coughing, talking, spitting, etc. Most of the time these respiratory droplets dry off. Even so, some bacteria are resistant to drying and can remain suspended in air for long period of time. Therefore, when a healthy person inhales these droplets, it may lead to respiratory infection.

☛ Ingestion
Gastrointestinal infections are typically caused by ingestion of the pathogens or their toxins. Thus, giving rise to a lot of diverse illnesses like waterborne, food-borne and hand-borne illnesses. These pathogens enter the gastrointestinal tract through the mouth and in some circumstances by means of the nose or eyes. Examples of diseases caused via ingestion include cholera, dysentery and food poisoning.

☛ Inoculation
When a bacteria is inoculated into the subcutaneous body tissue, it may lead to infection. For example, a deep wound might give a chance to Clostridium tetani a chance to cause a tetanus infection. Similarly, gangrene causing bacteria could also cause cellular death and tissue decay.

☛ Congenital
Pathogens that are able to cross the placental barrier and infect the fetus within the uterus are called as congenital infections. These infections can lead to congenital disorders within the baby.

Factors that Result in Bacterial Infection in Humans
We have already understood the terms pathogenicity and virulence. We have also understood the aspects that give bacteria its virulence and the modes of transmission of a pathogenic bacteria. But, how does bacteria cause diseases in humans? The following paragraphs will discuss the possible strategies of these microorganisms that result in illnesses.

☛ Adhesion
As we have seen earlier, fimbriae or pili helps the bacteria to attach itself to the site of infection. This is called as adhesion. This doesn’t happen by chance, but a certain reaction helps in adhesion. The surface receptors on the epithelial cells and also the adhesive structures (adhesins) on the bacterial surface are involved in this particular adhesion reaction. These adhesins are present on the fimbriae or fibrillae or pili. They include the virulence factors that makes the bacterial strain virulent. If these adhesins are lost, the bacteria becomes avirulent. Therefore, folks are immunized with distinct adhesins. This gives the body a chance to create immunity against the infectious bacteria.

☛ Invasiveness
When a bacteria is able to invade the host tissues, it can trigger a generalized or localized infection. For instance, a wound infections can result in streptococcal septicemia which is a generalized infection. A Staphylococcus abscess is far more of a localized infection.

☛ Toxigenicity
We have already noticed, bacteria are in a position to create toxins that result in an infection. There are two types of toxins produced by bacteria, these incorporate exotoxins and endotoxins. The exotoxins can diffuse within the surrounding medium and tend to be extremely potent when present even in minute amounts. These endotoxins are easily destroyed by heat. You’ll find particular exotoxins which might be known as essentially the most poisonous substances inside the world. As an example, 1 million guinea pigs can be killed by just 1 mg of botullinum toxin. They are typically produced by gram-positive bacteria and a couple of gram-negative bacteria like E.coli , Cholera vibrio, etc. Exotoxins show specific affinity towards particular tissues and every exotoxin has a diverse effect on the host.

The integral part of the gram-negative bacteria cell wall are endotoxins. They’re polysaccharide-protein-lipid complexes, which are extremely heat stable. The lipid A component imparts the toxicity to these endotoxins. They are released into the surrounding medium, only when the cell wall disintegrates. These endotoxins are dangerous only when present in big doses. They do not have certain pharmacological activities and have similar effects on host.

☛ Other Factors
Some bacteria include bacteriophages that give the organism its virulence. As an example, the diphtheria bacteria contains a bacteriophage that has a gene for toxin production. There are bacteria that contain plasmids and they’re responsible for the presence of surface antigens. These plasmids give the bacteria multiple drug resistance and hence the infection becomes tough to treat. Klebsiella pneumoniae and haemophilus influenzae are capsulated bacteria. These bacterial cells are covered by a capsule that helps them steer clear of phagocytosis. There are bacteria that carry their antigens on the capsules to carry out lytic activity inside the body cells.

Do All Bacteria Cause Illnesses?

No, not all bacteria trigger diseases. You’ll be surprised to understand, less than 1% bacteria have the capacity to cause illnesses. There are several beneficial bacteria that support plants, animals too as humans in various methods. Numerous commensal bacteria are harmless organisms that live on or inside our body, with out ever causing any type of illness or infection.

This is all about how bacteria cause diseases. As you’ll be able to see, you’ll find numerous modes of infection and diverse strategies of bacterial cells that lead to an infection. Remember, not all infections lead to disease. It truly is a quite rare natural event, that could happen when the body’s immune method fails to get rid of the infectious agents.