Microbiology Semester 2 Week 14

              Assalamualaikum and hi everyone... how are you all? I hope everyone will be fine as well... On Tuesday, before our class start, my classmates do their Pecha Kucha about a microbe based on topics provided to them.

             On Friday, Dr Asilah taught us about the microbial epidemiology and public health. Epidemiology is the study of the distribution and determinants of health-related events and the applica6on of this study to the control of health problems. Sporadic is occurs occasionally at irregular intervals. Endemic is a relatively steady low-level frequency at moderately regular intervals. Hyperendemic diseases is gradual increase in occurrence frequency above endemic level but not to epidemic level. Epidemic is a.k.a “outbreak” which is sudden increase in frequency above the normally expected number usually in a limited area and index case = first case of an epidemic. Pandemic is increase in disease occurrence within large population over wide region. Incidence is the number of new cases within a population during a specified time period. Prevalence is the total number of cases within a population. Epidemic Spread Patterns is common-source Epidemic is a group of persons are all exposed to an infectious agent from the same source and propagated Epidemic is transmission from one person to another. Types of Epidemiological Study is descriptive is the physical aspects of an existing disease and disease spread, analytical  is establishing cause-and-effect relationships in the occurrence of diseases in populations and experimental is designed to test the value of treatments, health programs, policy changes, etc.

          Three statistical measurements of disease frequency which is morbidity rate, prevalence rate and mortality rate. Morbidity rate is a.k.a. incidence rate which is number of new cases in a specified time period per unit of population. Prevalence rate is number of all cases in a specified time period per unit of population. Mortality rate is number of deaths (due to the disease) in a specified time period per unit of population. Disease Transmission and Emergence which is infection reservoirs and transmission and emerging and re-emerging infectious Diseases (ERID).  Infection Reservoirs and Transmissions is infection reservoirs, humans and animals,  Zoonoses are diseases that can be transmitted to humans from other vertebrates. Non-living is e.g. soil and water. Emerging and Re-emerging Infectious Diseases (ERID) is systematic epidemiology is study of ecological and social factors that influence the development of emerging and re-emerging infectious diseases. Nosocomial infections a.k.a. Hospital-acquired infections is from pathogens that develop within a healthcare facility and are acquired by patients while they are in the facility is e.g. antibiotic-resistant microbial strains, such as Methicillin-resistant Staphylococcus aureus (MRSA).

           Sources of nosocomial infections is endogenous pathogens is opportunistic pathogens present in the patients and activated by activities in the hospital and exogenous pathogens is not normally present in the patients but have entered into the patients from the hospital environment. Collective Immunity which is Herd Immunity and  Immunisation. Herd Immunity is collective resistance of a population to the spread of an infection and caused by the immunity of a large percentage of that population. Immunisation is the process whereby a person is made resistant to an infectious disease, typically via vaccination and vaccines stimulate the immune system to protect the person against subsequent infection. Immunologic adjuvant is any substance that acts to enhance immune responses when used in combination with specific vaccine. Seven types of vaccines which is attenuated vaccines which is live microbe that has been weakened. Inactivated vaccines is killed microbes. Subunit vaccines is include only components that stimulate the immune system. Toxoid vaccines is “Detoxified” toxins, called toxoids, are used against bacteria that secrete toxins. Conjugate vaccines is bacteria may possess polysaccharide coatings to disguise their antigens, therefore, immature immune systems are unable to recognize the bacteria, in conjugate vaccines, these polysaccharides are linked (or conjugated) with recognizable antigens, this linkage “teaches” the immune system to recognize those polysaccharide coatings in future infections. DNA vaccines is genetically-engineered DNA for microbial antigens are directly introduced into the host’s cells and the DNA then instructs those cells to create antigens and induce immune response. Recombinant vector vaccines is similar to DNA vaccines and DNA is introduced via vectors which may include attenuated microorganisms.

      

     
   

Microbiology Semester 2 Week 13

                Assalamualaikum and hi everyone... how are you all? I hope everyone will be fine as well... On Tuesday, before our class start, my classmates do their Pecha Kucha about a microbe based on topics provided to them.

                On Friday, Dr Asilah taught us about antigen and antibody. Antigens (Ag) is any agents capable of binding specifically to components of the immune response (e.g. antibodies). Immunogens is any agents capable of inducing an immune response. Requirements for immunogenicity is foreignness, high molecular weight (usually > 5000), chemical complexity and biodegradability. Major Classes of Antigens which is carbohydrates (polysaccharides) is potential (not always) immunogenic. Generally, ~ 6 sugar residues is recognized by antibody. Proteins is almost all are immunogenic. Generally, recognition by antibody is 15-22 amino acid residues. Lipids is rare (Often through conjugation with protein carriers). Nucleic acids is extremely poor (need conjugation with protein carriers). Contact points on the antigen for the immune system’s elements which is Epitopes / Antigenic determinants is the immunologically active portions of an antigen that reacts with antibodies or T-cell receptors. Epitopes can be sequential which is continuous and linear. Nonsequential is discontinuous, conformational and assembled topographic determinants. Types of responses generated is primary response (1st encounter) also known as the Priming Immunization. Antigen processing and lymphocytes proliferation and differentiation. Secondary response (2nd encounter) also known as the Memory or Anamnestic Response. Response quicker and the magnitude higher and mediated by B and T memory lymphocytes.

             Antibody (Ab) also called Immunoglobulins (Ig). Antibody (Ab) is a glycoprotein and also called Immunoglobulins (Ig). Depicted as a “Y” shaped structure consisting of 4 protein subunits which is 2 longer subunits is heavy (H) chain and identical and 2 shorter subunits light (L) chain, identical and two types (κ and λ chains). Recognition by antibody, antigens and epitopes. Antigen is molecules that antibody binds, can be proteins, polysaccharides (sugars), lipids or nucleic acids, can be located on the surface of the pathogen or excreted (toxin) by pathogen and the specific part of the Ag that the Ab binds is called the antigenic epitopes. Five classes of antibody which is IgM, IgG, IgE, IgD and IgA. Requirements for antibody production is only make Ab that are specific for antigens that one has been exposed to, make different classes of Ab with different functions and make high affinity antibody. High affinity antibody achieved by high affinity pre-existing B cells are clonally selected and select B cells with low affinity and increased affinity with development of Ab response which is affinity maturation. Differentiation into plasma or memory cells Plasma cells is majority, different lifespans (weeks to months) and secrete antibody. Memory cells is involved only those that have switched class. Memory cells for IgG, IgA and IgE not IgM or IgD. Retained Ig on their cell surfaces.

     

Microbiology Semester 2 Week 12

              Assalamualaikum and hi everyone... how are you all? I hope everyone will be fine as well... On Tuesday, before our class start, my classmates do their Pecha Kucha about a microbe based on topics provided to them. Later on, Dr. Asilah taught us about the introduction to immunology. Basically, Immune system  is includes various cells, tissues and organs, working collectively and defend against harmful pathogens, cells and substances. Primary lymphoid organs is production sites of immune cells and maturation sites for immune cells in the absence of antigen such as bone marrow, and thymus. Secondary lymphoid organs is maturation sites for antigen-driven immune cells, sites where immune cells encounter, bind with antigen which is proliferate and differentiate into fully mature, antigen specific effector cells.Innate Immune Response is non-specific, immune components are preformed, response magnitude is similar during the first and subsequent encounters and no memory is stored.

             On Friday, Dr Asilah continue about the introduction to immunology. Adaptive Immune Response u Specific is immune components are fully activated only after infection starts, response magnitude is higher in the second and subsequent encounters compared to the first and immunological memory is stored. Development of T and B cells is lymphocyte development diverges into two cell lines u T cells and B cells. This antigen-independent maturation occurs in two sites which is T cells in thymus and B cells in bone marrow. They have surface markers or receptors, which function to bind to receptors on other cells, bind to antigens and transmit and receive messages. The common receptor molecules which is major histocompatibility complex (MHC), cluster of differentiation (CD) and antigen-specific receptors. Antigenicity of a substance is determined by a combination of factors size, complexity and foreignness. Antigens are presented by professional antigen presenting cells (APCs), such as: Macrophages, Dendritic cells and B cells.

           Antigens presented on APCs will activate T and B cells. For T cells, this activation stimulates their differentiation into subtypes of T helper cells (Th), memory T cells, regulatory T cells (Treg) and cytotoxic T cells (Tc). T helper cells stimulate or activate other cells, including macrophages, B cells, Tc cells. Memory T cells store immunological memory. Regulatory T cells regulate other cells to prevent excessive inflammation and autoimmunity. Sometimes, B cells can be activated without the help of T helper cells. Referred to as T-independent activation. Most of the time, B cells require activation by of T helper cells. Following activation, B cells differentiate into memory B cells, regulatory B cells and plasma cells. Memory B cells store immunological memory. Regulatory B cells regulate other cells to prevent excessive inflammation and autoimmunity. Plasma cells launch billions of antibodies to attack the invaders. Antibodies disable the targets through neutralisation which block the receptor on a surface or the targets, neutralising them. Opsonisation is coat the targets, helping phagocytes to recognize them. Agglutination is link the targets with one another into large clumps, immobilizing them and enhancing their phagocytosis. Antitoxin action is bind to toxins produced by the targets, rendering them harmless.