Basics of Medical Microbiology

Basics of Medical Microbiology

Medical microbiology deals with studying the relationship between host and parasite and understanding the causative agent of disease.

In our daily life, human beings are constantly exposed to micro-organisms.
The interaction between human and micro-organisms may be useful or harmful interaction.
Parasitism can be explained a condition in which microbial population is benefited and the host is harmed.

Some important concepts in medical microbiology

1. Infection

  • In infection, a pathogen enters in a host body, lives and multiply in the host.
  • Generally, infection is caused due to the failure of host defence mechanism.
  • Due to the failure of host defence mechanism the microbial cells leads to infection.

2. Disease

  • The disease is a result of infection
  • When a disease is established the normal functioning of host body is disturbed and this disturbance results in signs and symptoms.
  • These pathogens not only multiply in the host but also releases some byproducts.
  • These byproducts may be toxic or non-toxic to host.

3.   Etiological agent

  • The etiological agent may be the causative agent of a disease
  • It may be an opportunistic pathogen

4.   Pathogen 

  • The pathogen may be defined as an organism that has an ability to cause a disease.
  • The pathogen first enters the host body, cause infection and then result in a disease.

5.   Fomites

  • Fomites are not harmful objects but they play important role in the transmission of the pathogen

6.   Pathogenicity

  • Pathogenicity is the ability of the pathogen to cause disease

7.   Virulence

  • Virulence is a degree of pathogenicity of pathogen

8.   Incubation period

  • The incubation period is a time taken by an organism to cause a disease and show its symptoms
  • That is the time between infection and appearance of signs and symptoms.

9.   Morbidity rate

  • Morbidity is a ratio of the number of people that are suffering from a disease to the total population.
  • It is expressed in percentage.
  • Morbidity rate = Number of people suffering from a disease/ Total population

10.  Mortality rate

  • The mortality rate is a ratio of number of fatalities due to disease to the total population
  • It is the death rate of people.
  • Mortality = Number of fatalities/Total population

11.  Opportunistic Pathogen

  • The opportunistic pathogen is an organism that is a part of normal body flora.
  • It is harmless but under the certain condition, the organism becomes pathogenic in nature.

12.  Prophylaxis

  • Prophylaxis is a prevention of disease.

13.  Carriers

  • Carriers are the infected host that carries the pathogen without showing any signs and symptoms.
  • Carriers play important role in the transmission of disease.

14.  Antigen

  • The antigen is the agent which induces the immune system to form antibodies.
  • The antigen may be a microbial cell or its byproducts.

15.  Antibody

  • The antibody is a glycoprotein molecule produce in response to antigen.
  • It is an immunoglobulin produce due to sensitization of immune system by antigen.

16.  Vaccine

  • It is an antigenic preparation which is induced in host body for developing immune response when a pathogen or its toxin enters host body.

17.  Immunity

  • Immunity can be defined by as a resistance shown by a host body against disease.


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