Microbiology

• Microbiology is the study of microorganisms, including bacteria, viruses, fungi, and parasites
• Microorganisms play important roles in various processes such as nutrient cycling and decomposition
• Microorganisms can be found everywhere in the environment, including in soil, water, and air
• Bacteria are single-celled prokaryotic organisms that can be classified based on their shape, arrangement, and staining properties
• Viruses are non-living infectious agents that require a host cell to replicate and cause diseases in humans, animals, and plants
• Fungi are eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds and mushrooms)
• Parasites are organisms that live on or inside another organism (host) and benefit at the expense of the host
• Microorganisms can cause infectious diseases in humans, which can be transmitted through various routes such as direct contact, ingestion, inhalation, and vector-borne transmission
• Common methods used to study microorganisms include microscopy, culture techniques, biochemical tests, and molecular techniques like PCR
• Antibiotics are drugs used to treat bacterial infections by inhibiting bacterial growth or killing the bacteria
• Antibiotic resistance is a global health concern that arises when bacteria develop mechanisms to resist the effects of antibiotics
• Vaccines are biological preparations that provide immunity against specific infectious diseases by stimulating the immune system to produce antibodies
• Immunization is the process of administering vaccines to individuals to protect them from infectious diseases
• The immune system plays a crucial role in defending the body against pathogens by recognizing and eliminating foreign invaders
• Immunodeficiency disorders are conditions in which the immune system is weakened, leading to increased susceptibility to infections
• Microbiologists study the characteristics, behavior, and interactions of microorganisms to understand their roles in health and disease
• Microorganisms are microscopic living organisms that include bacteria, viruses, fungi, and parasites
• Bacteria are single-celled prokaryotic organisms that can be classified based on their shape, arrangement, and staining properties
• Viruses are non-living infectious agents that require a host cell to replicate
• Fungi are eukaryotic organisms that can be unicellular (yeasts) or multicellular (molds)
• Parasites are organisms that live on or in a host organism and rely on the host for nutrients and survival
• Microorganisms can cause infectious diseases in humans through various mechanisms
• Pathogenic microorganisms can enter the body through different routes such as inhalation, ingestion, or direct contact with broken skin
• Once inside the body, microorganisms can evade the immune system and multiply, leading to infection and disease
• Common infectious diseases caused by microorganisms include tuberculosis, influenza, malaria, and HIV/AIDS
• Microorganisms play important roles in various ecological processes
• Microorganisms are essential for nutrient cycling, decomposition, and soil formation in the environment
• Some microorganisms can be used in biotechnological applications such as food production, bioremediation, and pharmaceuticals
• Microorganisms are also used in research and development of new antibiotics and vaccines
• Microbial control and prevention strategies are important in healthcare settings
• Proper hand hygiene, disinfection, sterilization, and vaccination are key strategies to prevent the spread of infectious microorganisms in healthcare facilities
• Antimicrobial resistance is a growing concern and proper antibiotic stewardship is essential to combat this global health threat
• Adaptive response


  • Specific to a particular antigen
  • Slow at first exposure, rapid at secondary exposures
  • Involves lymphocytes: T-cells (cellular immunity), B-cells (humoral immunity), Antibodies
• 1. cells


  • Made in the bone marrow, mature in the thymus, and hang around in the bloodstream and lymph organs: lymph nodes, tonsils, spleen
  • Require activation by antigens presented by antigen presenting cells
  • Come in three main types: Th, CTL, Treg
• Helper T-cells


  • Coordinate immune responses
  • Activated in a complex manner by antigens on MHC II molecules and by cytokines
  • Secrete massive amount of cytokines – stimulate inflammation and immune cell activation
  • Super-activate macrophages
  • Activate B-cells
  • Differentiate into memory T-cells
• Cytotoxic T-lymphocytes


  • Directly kill cells that display abnormal MHC I molecules
  • Activated by antigens on MHC I molecules of Dendritic cells and maximally activated by Th cells
  • Traffic to the site of infection and scan all nearby MHC I molecules for their cognate antigen
  • If found, the CTL will trigger apoptosis in the infected cell
• Regulatory T-cells


  • Suppress the immune system de-activating it
  • Important to deactivate the mechanisms of immunity once an infection has cleared
• 1. cells


  • Made and mature in the bone marrow, and hang around in the bloodstream and lymph organs: lymph nodes, tonsils, spleen
  • Bind to a specific antigen and clone itself and produces antibodies
• Antibodies


  • Bind to antigens on pathogens, marking and highlighting them to immune system (opsonisation)
  • Bind to antigens on pathogens, interfering with pathogenesis (neutralisation)
  • Bind to antigens on pathogens, sticking them together (agglutination)
• 1. cell activation by Th-cells

  1. B-cell binds to antigen and re-processes it into lots of small antigens and displays it on their MHC II molecule

  2. Th-cells can now be stimulated by the antigen on the B-cell MHC II molecule, which in turn activates the B-cell to its full potential