Introduction to Antigen-Antibody Reactions

Introduction to Antigen-Antibody Reactions

Introduction to Antigen-Antibody Reactions The interactions between antigens and antibodies are known as antigen–antibody reactions. The reactions are highly specific, and an antigen reacts only with antibodies produced by itself or with closely related antigens. Antibodies recognize molecular shapes (epitopes) on antigens. Generally, the better the fit of the epitope (in terms of geometry and … Read more Introduction to Antigen-Antibody Reactions

Laboratory diagnosis of Streptococcus pyogenes

Laboratory diagnosis of Streptococcus pyogenes

Laboratory diagnosis of Streptococcus pyogenes 1. Specimens Throat swab Pus Cerebrospinal fluid Blood Serum for antibody determinant 2. Smear Gram staining Purple color cocci in chain arrangement Not to be confused with Viridans Streptococci from throat swab sample since both have same appreance 3. Culture Culture on blood agar Addition of bacitracin in inoculum: S … Read more Laboratory diagnosis of Streptococcus pyogenes

Properties and Function of different classes of Antibodies

Properties and Function of different classes of Antibodies

Properties and Function of different classes of Antibodies Antibodies are glycoproteins produced in membrane-bound or secreted form by B lymphocytes in response to exposure to foreign structures known as antigens. The human immunoglobulins are a family of proteins that confer humoral immunity and perform vital roles in promoting cellular immunity. There are five classes of … Read more Properties and Function of different classes of Antibodies

Antibody- Introduction, Structure and Classes

Antibody- Structure-and-Classes

Antibody- Introduction, Structure and Classes Antibodies are often referred to as immunoglobulins (immune proteins).  Antibodies, or Y-shaped immunoglobulins, are proteins found in the blood that help to fight against foreign substances called antigens. Antigens, which are usually proteins or polysaccharides, stimulate the immune system to produce antibodies. The antibodies inactivate the antigen and help to remove … Read more Antibody- Introduction, Structure and Classes

Clinical manifestation and Pathogenesis of Streptococcus pyogenes

Clinical manifestation and Pathogenesis of Streptococcus pyogenes

Clinical manifestation and Pathogenesis of Streptococcus pyogenes Virulence factors of Streptococcus pyogenes A. Antigenic structure M protein: rod like coiled structure with two major structural classes; Class I and Class II ;major virulence factor;resist phagocytosis and intracellular killing by polymorphonuclear leukocytes in the absence of antibodies. B. Toxins and enzymes Streptokinase It is also called … Read more Clinical manifestation and Pathogenesis of Streptococcus pyogenes

Habitat and Morphology of Shigella dysenteriae

Habitat and Morphology of Shigella dysenteriae

Habitat and Morphology of Shigella dysenteriae Habitat of Shigella dysenteriae They are found worldwide. Humans are only the natural host. They are also found in human intestinal tract. They are mostly found in the area where there is overcrowded. Prevalent in low waste management areas and no safe drinking water supply. Houseflies serves as vectors. … Read more Habitat and Morphology of Shigella dysenteriae

Habitat and Morphology of Klebsiella pneumoniae

Habitat and Morphology of Klebsiella pneumoniae

Habitat and Morphology of Klebsiella pneumoniae Habitat of Klebsiella pneumoniae They are found in mouth, skin and intestinal tract of human beings. They are also found in soil, water and sewage. Also found in bowel and respiratory tract of humans and animals. Found in the hands of hospital personnel. They are responsible for community and hospital … Read more Habitat and Morphology of Klebsiella pneumoniae

Habitat and Morphology of Listeria monocytogenes

Habitat and Morphology of Listeria monocytogenes

Habitat and Morphology of Listeria monocytogenes Habitat of Listeria monocytogenes They are the natural pathogens of wide range of animals, birds, fish, ticks and crustacean. They are saprophytic in soil, water, sewage and plants decaying. They occasionally colonizes the human gastrointestinal tract (1-10%). They can be isolated from foods for human consumption, including raw and … Read more Habitat and Morphology of Listeria monocytogenes

Habitat and Morphology of Corynebacterium diphtheriae

Habitat and Morphology of Corynebacterium diphtheriae

Habitat and Morphology of Corynebacterium diphtheriae Habitat of Corynebacterium diphtheriae Found in nasopharynx as well as in skin lesions, which actually represent a reservoir for the spread of diphtheria. Also found in mouth, throat, nose, skin and wound of infected person. Animals do not easily contract diphtheria. Patients carry toxigenic organism upto 3 months after infection. … Read more Habitat and Morphology of Corynebacterium diphtheriae

Habitat and Morphology of Neisseria gonorrhoeae

Habitat and Morphology of Neisseria gonorrhoeae

Habitat and Morphology of Neisseria gonorrhoeae Habitat of Neisseria gonorrhoeae Human is only the natural host. Found in human urogenital tract. Rectal carriage in healthy individuals. Typically seen in pus cells (intracellular) Found intracellularly in polymorphonuclear leukocytes, or a specific category of white blood cells with varying shapes of nuclei. Morphology of Neisseria gonorrhoeae Gram –ve … Read more Habitat and Morphology of Neisseria gonorrhoeae

Habitat and Morphology of Streptococcus pyogenes

Habitat and Morphology of Streptococcus pyogenes

Habitat and Morphology of Streptococcus pyogenes Habitat of Streptococcus pyogenes They are found in throat and skin of human. They are commensals of upper respiratory tract. Carrier rate of S. pyogenes in the respiratory tract is only few in adults, over 10% in children attending kindergarten. Opportunistic pathogens May survive in dust for some times. Morphology … Read more Habitat and Morphology of Streptococcus pyogenes

Cultural characteristics of Clostridium perfringens

Cultural characteristics of Clostridium perfringens

Cultural characteristics of Clostridium perfringens It is an anaerobic bacteria but can grow under micro-aerophilic condition. They form large, translucent, flat and filamentous colonies with irregular edges. PH: 5.5 to 8.0 (Average PH: 7.2) Temperature: 20°C to 50°C (Average: 37°C) At 45°C, generation time is 10 minutes. Clostridium perfringens on Robertson’s Cooked Meat Broth Saccharolytic … Read more Cultural characteristics of Clostridium perfringens