BIOL20342 Microbiology


Your normal flora and environment are the most likely to transmit infectious diseases.

How much do you agree with this opinion?



Microorganisms exist in every part of the world, such as water, soil, plants, and animals.

Because microbes are essential in maintaining the earth’s cycles, life will be unbalanced.

Microorganisms are a normal part of every human body.

You can find microorganisms in the internal tissues (e.g.

In healthy humans, blood, brain and muscle are all free of microorganisms.

However, the organisms found in the environment are present on the surfaces of the tissues like skin, mucous membrane, and many others.

Although there are a few protists, the majority of the normal flora in a human is made up of bacteria and fungi.

Although a foetus born in the womb of a mother is immune to microorganisms, it becomes vulnerable once it gives birth and gets into contact with the vaginal bacteria.

After just a few hours after birth, the oral flora and the nasopharyngeal fauna develop.

Within a few days the intestinal flora emerges.

This report will provide information about the normal flora in the human body as well as the infections they can cause (Murray and al.

There are two types of flora.

The resident flora: It is composed of moderately fixed microorganisms found in a particular zone at a given time; if it is disturbed, it quickly heals.

The transient fauna – This is the mix of pathogenic as well as non-pathogenic microorganisms. They live on the skin or mucous membranes for several days, sometimes even weeks.

They don’t live on the skin permanently and aren’t responsible for causing disease.

Individuals of the transient vegetation have little to no centrality as long as the inhabitant verdure is in place.

Transient microorganisms could colonize and multiply in the environment if it is damaged (Tille, 2013).

A wide variety of microorganisms are found in the human body. Many of them perform essential tasks for human survival.

Normal flora is defined as those organisms that are easily accessible and do not cause disease under normal conditions.

There are approximately 5,000 to 10,000 types of life in the human body.

Microbial cells are far less complex than human cells. There are about 1000 trillion (1015), microorganisms in the body, which is ten-times as many as human cells (1014).

Despite the fact that most vegetation is found on surfaces, the majority of microorganisms living in the body (Lieberman 2014).

Microorganisms are able to colonize any anatomical region of the body without difficulty and continue growing there, unassisted by the host.

Analyzing normal flora within the body is helpful in understanding how colonization, commensalism can be beneficial and what causes a specific condition.

These are the common microorganisms associated with different parts of the human body. (Nash 2015).


Because eyes are exposed to external conditions, they may interact with other organisms.

The most likely reason that the conjunctival plants are not as healthy is because of the lysozyme, which is secreted in tears.

Lysozyme has been shown to inhibit the growth of microscopic organisms.

It was discovered that certain microorganisms like Staphylococcus epidermidis (as listed in table 1) may be present on conjunctiva.

In normal conditions, these organisms do not cause eye damage.

However, these lifeforms can cause eye damage in some cases (Mahon, et al.

Table 1: Normal microflora for eyes


Additional attention is paid to the condition of the ears.

Table 2 shows that the ear has typical verdure.

The ear also has typical small-scale vegetation.

Pseudomonas, a microorganism, may cause pioneering contaminations of the ear (Klatt and al.

Table 2: Average microflora in the ear


Sometimes enterobacteria may be present


The trachea, nasopharynx, and trachea are mainly composed of bacteria genera that can be found in the common oral cavity, such as alpha-and-ss-hemolytic streptococci. However, other bacteria, including staphylococci.

Potentially pathogenic living substances, such as Haemophilus or mycoplasmas and pneumococci, may also be found in the pharynx.

The location where pathogens are most likely to colonize the upper respiratory tract, such as C. diphtheriae and Neisseriae menningitides, could be considered the primary site of ambush.

The fact that small particles and other tiny life forms can’t easily reach the lower respiratory tract (little brochi and alveoli), makes it seem sterile.

These microorganisms may reach these places if they are protected by safeguard systems (e.g. alveolar macrophages) that are absent in pharynx (Khanna, Tosh, 2014).

Table 3: Normal microflora in the nose and Naophyrynx


The skin is extremely resistant to the colonization of organisms due to its sebaceous and sweat-soaked emissions during pre-adulthood.

Whole skin, which is roughly 2 meters in area, can support approximately 1010 microorganisms.

Table 4 shows the typical life forms that are found.

The skin is a very solid mechanical barrier to microbial attacks and only a handful of life forms can enter it due to the fact the outer layer of skin cells (known as keratinocytes) is thick and tightly packed (Lloyd-Price et al. 2016).

Table 4: List of common microorganisms that are often found on the human skin



The microflora in common nails is the same as that found on the skin.

Dependent on the contact between the nails and clean particles, different materials and other unneeded substances may attach below the nail.

These invisible particles, regardless of skin type, can carry bacteria and microorganisms.

Aspergillus (Parham 2014), Penicillium Cladosporium and Mucor are all real types of developments that can be found under nails.

The stomach-related microbes, commonly known as ‘gut verdure,’ can seperate certain nutrients, for example complex starches.

Anaerobes account for the largest proportion of these microscopic commensal organisms. This means that they survive in an environment with little oxygen.

If brought down resistant, a large number of microorganisms from the verdure could be used to become entrepreneurial pathogens (Blaser 2014.

This illustration shows typical microbial plants of the various organs of the gastrointestinal tract.

Tooth and gums in your oral cavity are the main points of normal flora, which cannot be effectively removed.

The nearness of the first teeth in a child’s mouth opens up new pathways for microbial colonization.

Hydrochloric Acid (Sender and al.) destroys microscopic organisms removed from the mouth to stomach.

Diphtheroids, Eikenella corridense, S. aureus and beta-haemolytic streptococci are just a few of the microorganisms that can be found in an oral hole.

Viridans Streptococci (Table 5-).

Table 5: The normal microflora for oral depression


Due to its sharpness, stomach is generally an antagonistic environment for microscopic animals.

Stomach is home to microorganisms, both those who gulp for the food and those not stuck in the mouth.

Stomach is acidic at pH between 2-3.

Causticity reduces the bacterial count, which is highest after meals (roughly 103 to106 creatures/g of substance), and lowest (much more often imperceptible after assimilation) (Kohler.

The common microscopic organisms that are found in stomachs include Streptococcus species, Staphylococcus species spp and Lactobacillus. (Table 6).

Table 6: Normal microflora in the stomach

Staphylococcus spp.

Helicobacter piylori

Small Digestive System

It can be separated into three sections: jejunum, duodenum and ileum.

The first 25 cm zone in small digestive tract is called duodenum.

Each microscopic organism in the region is not immune to the effects of acidic stomach juices, inhibitory bile and pancreatic emission.

Gram positive cocci are the most common microorganisms. They include diphtheroids and Enterobacter Faecalis.

One time in a while, Candida albicans is found in this section of the digestive system (Belkaid/Segre 2014).

The 7th section of the digestive tract’s distal portion is called the ileum. This is where pH begins to rise and is more toward soluble.

Anaerobic Gram Negative microscopic organisms (GMOs) and many individuals from the Enterobacteriacae family begin to colonize this region of the digestive tract because of an ascend in pH.

This allows normal microbes to co-exist with Enterococci, Enterobacteria and Clostridium species, Clostridium species, Bacteriodes and Lactobacillus species.

Table 7: Normal microflora in small digestive systems

Enterobacteriaceae Individuals

Internal Organ

It is also called colon.

It is responsible for supporting different qualities of microorganisms.

This is why the internal organ supports a high number of life forms (10-12 life forms/gm wet weight stool).

The digestive organ is a huge fermentor of microorganisms that includes anaerobes and Gram negative microscopic animals.

In addition, the colon contains both Gram positive spore-framing and non-spore shape poles (Table 8)

E. coli, a member of the Enterobacteriacae famiy, is one of the most common (Zhou

Table 8: Normal microflora in an internal organ

Urogenital microflora

The urogenital framework is home to a variety of organisms (Table 9).

S. epidermidis (enterococci), and diphtheroids are all found in the front of the urethra.

E coli, Proteus and Neisseria (nonpathogenic varieties) are all accounted for occasionally.

Due to the common greenery found in the urine, care must be taken when clinically diagnosing pee societies. These creatures may be present at a level of up to 104/ml in pee tests (Nardone 2015 and Compare 2015).

The kind of bacteria found in the vagina is dependent on the host’s hormonal and pH levels.

In the first month of life, female babies experience a high vaginal pH (about 5)

Glycogen emission continues at pubescence and pH drops. Ladies gain mature greenery that includes L. acidophilus (corynebacteria), peptostreptococci and staphylococci. Steptococci and Bacteroides.

Menopause causes pH to rise again and less glycogen is released. The verdure then returns to the prepubescent state.

Torulopsis and Candida yeasts are occasionally found in the vagina (10-30 percent of women); they sometimes increase and can cause vaginitis. (Wang & Yang 2013, 2013).

Infections caused By Normal Flora

There are several types of infections caused in part by microbes.

Nosocomial Infections

Nosocomial refers to the Greek word meaning “healing facility”.

Nosocomial disease is a condition that strikes patients who are in healing facilities during their time in a doctor’s facility.

According to a gauge, 5-15% of all clinic patients are susceptible to Nosocomial infections and approximately 20,000. People die each year from these diseases.

Specialists, medical staff and visitors can also contract nosocomial diseases.

Because healing centers treat patients with microbial pathogenic infections, their facilities are contaminated with a wide range of pathogenic living creatures.

The possibility exists that patients and healing center staff may become infected by living organisms.

Numerous components are involved in nosocomial infection. These include microorganisms found in the healing facility, immuno-traded away status of the host, and the transmission chain within the clinic. (Sommer und Backhed 2013, 2013).

Table 10: Most common nosocomial diseases

Opportunities infections

The body’s microbial flora is usually safe. It often protects the body from pathogens.

These inhabitant microbial specialist may, however create illness in the host in certain situations.

Astute pathogens are also known as these specialists. These microorganisms can cause disease in the host.

These can include infection with virus operators such as HIV, unhealthiness of the host, cancer, alcohol addiction, tumor, diabetes and leukemia. They also include surgical wounds and invulnerable concealment that is triggered by sedate therapy, hereditary disorders, and so on (Alonso, Guarner 2013).

It is a bacterium that can be found in large intestinal tracts.

It isn’t likely to cause any harm because of its length in large intestinal.

However, it could cause problems in different areas, such as the urinary bladder, spinal cord, lung, peritoneal pit, wounds, or even the urinary bladder.

Living beings that are smaller than the expected scale flora in the oral pit can cause tooth rot and gum problems.

AIDS patients have often been found to be suffering from artful contamination.

You might also have other viral diseases that could be linked to contamination by intelligent life forms.

Many infections, such as echoviruses or adenovirus, are found in the body.

However, in a traded host, these infections could cause severe diseases.

Neisseria menetidis, an ordinary inhabitant of the respiratory tract, and Streptococcus pneumoniae, a common occupant in the nose and throat may also cause pioneering contaminations that lead to real illnesses in certain conditions (Wade 2013).

Candida albicans is present in the normal micro-flora of the oral cavity, skin, vaginal and vaginal areas.

However, similar Candida can cause oral thrush, nail disease, and vaginal yeast infections in immuno-bargained hosts for a variety of reasons (Olsen 2016,).

Methods of transmission

The spread of infection or contaminated disease may occur from one person to the next via coordinate contact. However, the illness-causing operator can spread the infection starting at one location and then spreading to others by a variety.

The pathogen could be passed from one person to another, through water, nourishment and air, or by blood and blood items transfusions.

Different transmission methods for sicknesses are clearly illustrated by Dewhirst, et al.

Person to person contact

Numerous bacterial, viral, or parasitic illnesses have been identified that can easily be passed from one person to another by contact.

Tuberculosis, caused by Mycobacterium tuberculosis, and little pox are two examples of illnesses that can be transmitted by close contact.

Tannock (2015) states that disease can be transmitted to the unpowerful host when the host and the source or supplies of pathogens interact with one another (Tannock 2015).

Transmission Air-Borne

A wide range of viral and bacteria pathogens can cause respiratory illnesses.

They are easily identifiable as tiny “vaporizers” or “bead centers”.

These pressure-packed canned items can travel several meters through the air and back and forth movement. They can reach their host and cause illness/pollution.

These ‘beadcores’ can be a major source of airborne illnesses in both humans and animals (Grice & Segre 2011, p.

Water-Borne Transmission

A variety of irresistible operators, both human and animal, are transmitted by water, particularly in developing nations that do not have chlorination offices.

Water is frequently decontaminated by fecal material of winged animals and creatures.

It is known that many pathogens and creatures may be found in the dung of winged creatures.

When the population consumes such contaminated water, it becomes tainted.

Giardiasis (amoebiasis), cholera and salmonellosis are just a few examples of regular diseases that are transmitted via water (Murray

Relationship Host-Parasite

Parasitism is a relationship in which an organism lives or damages the host.

There are many parasitic experts, such as microscopic organisms and infections, protozoa, helminths, etc.

The living organism that lives on the host’s surface is called “ectoparasite”, whereas the one that lives within the host is known as “endoparasite”.

This relationship can have harmful effects on the host if it is disturbed.

It has been shown that vaginal infections can be caused by Candida albicans or Gardenerella bacteria (Nami and al.

Virulence Factors

The term “harmfulness” refers to the degree of pathogenicity a pathogen has.

It can also be described as the relative power of a species to cause an illness.

The Latin word virulentus, which means “brimming over with harm”, is what gave rise to the term harmfulness.

The term harmfulness has been associated with a variety of components that are created by pathogenic creatures, such as growths, parasites and microorganisms.

Most pathogenic organisms are composed of proteins or other atoms which are combined with proteins.

These proteins can be encoded by the chromosomal DNA of pathogenic life forms or viral nucleic Acids or plasmids.

The pathogens can cause sickness by using a variety of tools, such as bond, colonization and intrusion, invulnerable react restraint or poisons (Struycka, 2014).

It was discovered that certain microorganisms attach to the host cells’ surface when they access the host.

These atoms/structures, which aid in authoritatively with the respective have cell receptors, are known as “adhesins”.

It has been shown that pathogenesis can be affected by the adhesion to specific pathogens.

Streptococcus mutantis, a Gram Positive bacterium associated with tooth decay, can demonstrate this.

It attaches to the tooth surface via glycocalyxglucosyltransferase. A catalyst provided by S. mutans changes glucose into a sticky polysaccharide called Dextran, which forms glycocalyx.

Actinomyces possess fimbriae, which attach to S.mutans’ glycocalyx. This helps to arrange plaques.

E. coli (and Shigella) are also enteropathogenic microbes. They have adhesins in the fimbrae, which attach to the host cells of the small digestive system.

Glycocalyx can be translated as’sugar coat’.

It is either made of polysaccharide, or mixed with polypeptides.

The outside surface of the bacterial cell divider’s bacterial cell divider’s bacterial cell divider’s glycocalyx is made up of a thick, sticky polymeric material.

Different types of microorganisms have different arrangements of glycocalyx.

Glycocalyx is released by the bacterial cell.

If glycocalyx is found on the bacterial surface, it’s called ‘container.’


Glycocalyx is formed around the bacterial cells to form the capsule.

This is linked to an increased degree of destructiveness in certain bacteria pathogens.

A decreased ability to phagocytosis the contaminated host has been linked to the closeness of containers on microscopic organisms.

A concoction piece of container prevents the connection of phagocytes and bacterial cells.

The container is a major cause of harm for Streptococcus pneumococcal pneumoniae.

Gram negative microbes have hair-like structures.

These structures are called “fimbria”, (particular).

Every bacterial cell surface will have a different number of fimbriae.

It is possible for the number to vary between a few and hundreds per cell.

This aid is in connection with microscopic organisms inside has cells.


These are made by some pathogenic microbes.

The proteins that make haemolysins can be used to lyse the red platelets (RBCs).

Clostridium perfringence (causes Gas Gangrene) is one example of a bacterial species that produces haemolysins.

According to Weinstein and Swartz (2014), haemolysin can be described as a destructiveness-figure pathogenesis of haemolysin that delivers pathogenic living things.


Toxins are toxic substances created by pathogenic microorganisms.

These toxic substances are frequently fundamental causing factors of pathogenesis.

These toxins can be either delivered to the body through many diseases or externally.

Consuming polluted food can cause poisoning and debilitating microorganisms can deliver poisons in human nutrition.

These can be left in “ruined” nourishment and can cause disease even after cooking.

Following an attack on the host by microorganisms, there is a subsequent foundation and duplicate of the specialist.

It is possible for a contamination to cause an obvious disease.

However, the disease could be transmitted to other people by the person who was contaminated.

The illness might be short-term or persistent.

Any mode of transmission could transmit the disease, as shown in Maddi and Scannapieco (2013).

Invasion refers to the demonstration of the spread of pathogen in host tissue tissues.

“Obtrusiveness” refers to the capacity of pathogenic organisms to invade, replicate and spread in the host body.

Pathogenicity can be described as the state or nature that is capable of causing illness.

Pathogenicity is the ability to cause illness by any pathogenic operator.

The degree of pathogenicity determines the severity of the illness (Dewhirst and al.

Limitations on the ability of living things to produce poisonous, synthetic substances that can harm the host tissue or cause infections are not allowed.

The death rates and ability to inflict tissue on others is a measure of how pathogenic a lifeform is.

A person infected with a disease and a potential source for infection to others plays a critical role in the study of disease transmission.

It has been observed that many people carry pathogenic living creatures and can transmit them to others in an indirect or direct manner.

Some people might not show signs or symptoms but may be carriers of the pathogens.

These are called transporters.

They are the living repositories that carry disease.

Human transporters play an essential role in transmitting diseases like hepatitis and diphtheria.

We have identified four distinct types of carriers.

(1) Active carrier: A person who has a clinically confirmed case.

(2) Convalescent Carrier – A person who is able to carry a wide range of pathogenic forms after undergoing treatment for malady.

(3) Healthy carrier – A person who transmits the diseased life form to another person without suffering from side effects or clinical signs.

(4) Incubatory carrier: A person who is responsible for the incubation of many pathogenic organisms but not showing signs of sickness. But, at some point, develops a serious clinical infection.

Incubatory transporters could transmit pathogenic life forms from one person to another.


This means that normal flora can become malady if they are not found in their natural habitat.

Escherichiacoli, which is a common organism in the digestive system, can cause infections of the urinary tract if it gets into the bladder.

There is typical greenery on the body and within it.

Some ordinary vegetation is restricted to certain areas of the body.

E-Coli microorganisms are found in the digestive and rectum organs as well as the skin around the rear.

When vegetation is “moved”, it can cause contamination. This could be in the mouth (from not wiping after a defecation), or in the vaginal (from wiping from front to back).

Some diseases can make regular verdure duplicate.

For example, yeast can be found in the skin, vagina, and mouth.

Diabetes patients may experience yeast contaminations in the vagina, mouth, and skin folds.

The majority of typical body vegetation supports the creature.

The typical body verdure is a mixture of space and assets that can be used to spread pathogens.

A typical body verdure is a microorganism that can enter a body area and cause disease.

These microscopic organisms have been called sharp pathogens.

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