Microbiology Notes By Sagar Aryal
Biochemical Test of Bacteria Biochemical reactions are very important in the identification of bacterial isolates and in the identification of different bacterial species. These tests depend on the presence of certain enzymes, such as catalase, oxidase, urease, gelatinase, etc., produced by the bacteria. Different bacteria produce varying spectra of enzymes. For example, some enzymes are … Read more Biochemical Test of Bacteria
Biochemical Test of Streptococcus pyogenes Characteristics Properties (Streptococcus pyogenes) CAMP Negative (-ve) Capsule Capsulated Catalase Negative (-ve) Gram Staining Positive (+ve) Hemolysis Beta Motility Non-Motile OF (Oxidative-Fermentative) Fac. Anaerobes PYR Positive (+ve) Shape Cocci Spore Non-Sporing Urease Negative (-ve) VP (Voges Proskauer) Negative (-ve) 6.5% NaCl Growth Negative (-ve) Fermentation of Adonitol Negative (-ve) Arabinose … Read more Biochemical Test 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
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 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
Bacitracin Susceptibility Test- Principle, Procedure and Result Interpretation Objectives of Bacitracin Susceptibility Test This test is used for presumptive identification and differentiation of beta-hemolytic group A streptococci (Streptococcus pyogenes– susceptible) from other beta-hemolytic streptococci. It is also used to distinguish staphylococci species (resistant) from micrococci (susceptible). Principle of Bacitracin Susceptibility Test The antibiotic bacitracin inhibits the … Read more Bacitracin Susceptibility Test- Principle, Procedure and Result Interpretation