The Relationship between Microbiology and Disease

Relationship between Microbiology and Disease
There is a strong relationship between microbiology and disease. Even though a small percentage of microorganisms are pathogenic or disease causing, the types of diseases that they can cause can be very serious. There are many microorganisms that under normal conditions do not produce any type of disease. These microorganisms are part of our body’s normal flora. The main locations for these types of microorganism are the nose, throat, eyes, mouth, skin, large intestine, and urinary system. A good example is Escherichia coli (E. coli) which normally is found in the large intestines. However, if E. coli gains access to the spinal cord, wounds, lungs, or urinary bladder, it could cause meningitis, abscesses, pulmonary infections, or urinary tract infections respectively.

There are many types of bacteria that cause diseases of the skin. Impetigo, a superficial skin infection, is caused by Staphylococcus aureus and sometimes Streptococcus pyogenes. A well known bacterial disease, acne, is caused by Propionibacterium acnes. Impetigo is most commonly found occurring in toddlers and grade school children. The characteristics of impetigo include pustules that become crusted. They sometimes rupture. It is spread by contact and the bacteria can penetrate the skin through a minor abrasion of even an insect bite. Acne affects more than 17 million people. Propionibacterium acnes cause inflammatory acne. It is commonly found on the skin.

The bacterial diseases of the nervous system can be very serious. Bacteria meningitis can be caused by three different bacteria: Streptococcus pnemoniae, Haemophilis meninigitidis, and Neisseria meninigitidis. Death from bacterial meningitis occurs very quickly most often. The most common type of meningitis that we hear about occurring in college dormitories and military barracks is meningococcal meningitis which is caused by Neisseria meninigitidis. There are now vaccines available that most colleges require incoming students to receive.
Leprosy is caused by Mycobacterium leprae. It is probably the only bacterium that grows in the peripheral nervous system (the nerves).

Sepsis is the growth of microorganisms in the blood. It usually is a result from a focus infection in the body. A diseases that made headlines a few years ago, anthrax, is caused by Bacillus anthracis. Receiving a bite from a cat or dog can also be very harmful. Pasteurella multocida, which can be caused by a dog bite or a cat bite, can cause septicemia.
Streptococcal Pharyngitis (also known as Strep Throat) is caused by Streptococcus pyogenes. Otitis media (ear infection) usually occurs as a complication of nose and throat infections. Some of the bacteria that cause otitis media include Streptococcus pneumoniae, Streptococcus pyogenes, and Staphylococcus aureus.

It is very important to know if a person is suffering from a virus or a bacterial infection. Antibiotics do not work against viruses. However, there are also some bacteria that are resistant to antibiotics. Gram-negative bacteria are resistant to penicillin. Penicillin interferes with peptidoglycan synthesis. Gram-positive bacteria cell walls consist of many layers of peptidoglycan, whereas gram-negative bacteria cell walls have a lipopolysaccharide-lipoprotein-phospholipid outer membrane that surrounds a thin layer of peptidoglycan. A gram stain is usually the first test performed to differentiate between gram-positive and gram-negative bacteria. Knowing the type of bacteria aids in the treatment of the disease.
The relationship between microbiology and disease will never end.


Gerard Tortora, Berdell Funke and Christine Case. Microbiology: An Introduction Media Update (8th edition) Pearson Education, Inc. publishing as Benjamin Cummings,