Online microbiology notes by SAGAR ARYAL
Potassium hydroxide (KOH) test Objective To visualize the fungal element in the clinical specimens. To examine skin scrapings or flakes and hair for the presence of hyphae and arthroconidia in suspected dermatophyte infections. Principle Potassium hydroxide (KOH) can be used on clinical specimens to clear cellular material and for better visualization of fungal elements. KOH … Read morePotassium hydroxide (KOH) test
Nitrite Reduction Test Objective To determine the ability of an organism to reduce nitrites to gaseous nitrogen or to other compounds containing nitrogen. Principle Nitrate reduction by bacteria is mediated by nitrate reductase and indicates that the organism can use NO3– as an electron acceptor during anaerobic respiration and reduce nitrate to nitrite. Nitrite, on the … Read moreNitrite Reduction Test
Phenylalanine Deaminase Test Objectives of Phenylalanine Deaminase Test To determine the ability of an organism to oxidatively deaminate phenylalanine to phenylpyruvic acid. To differentiate enteric Gram-negative bacilli on the basis of their ability to produce phenylpyruvic acid from phenylalanine. Principle of Phenylalanine Deaminase Test Phenylalanine deaminase medium tests the ability of an organism to produce the enzyme … Read morePhenylalanine Deaminase Test
Triple Sugar Iron Agar (TSIA) Test Objectives of TSIA Test To determine whether a gram negative bacilli ferments glucose and lactose or sucrose and forms hydrogen sulfide (H2S). To differentiate members of the Enterobacteriaceae family from other gram-negative rods. Principle of TSIA Test The Triple Sugar Iron agar (TSIA) test is designed to differentiate among … Read moreTriple Sugar Iron Agar (TSIA) Test
Casein Hydrolysis Test Objectives of Casein Hydrolysis Test To determine the ability of the organism to degrade the casein protein. To differentiate the organism on the basis of production of exoenzyme proteinase (caseinase) Principle of Casein Hydrolysis Test Casein is a macromolecule composed of amino acids linked together by peptide bonds, CO-NH. Some microorganism have the ability … Read moreCasein Hydrolysis Test
Bile Esculin Test Objectives of Bile Esculin Test To identify Enterococci and group D Streptococci based on the ability of an organism to hydrolyze esculin in presence of bile. To differentiates enterococci and group D streptococci from non–group D viridans streptococci. Principle of Bile Esculin Test Esculin is a glycoside (a sugar molecule bonded by an acetyl linkage … Read moreBile Esculin Test
Objective of Beta (β)-Lactamase Test To detect the enzyme beta-lactamase, which confers penicillin resistance to various bacterial organisms. Principle of Beta (β)-Lactamase Test Various bacteria produce a class of enzymes called beta-lactamases, which may be mediated by genes on plasmids or chromosomes. Production of beta-lactamase may be constitutive or induced by exposure to antimicrobials. Beta-lactamases hydrolyze (and thereby inactivate) … Read moreBeta (β)-Lactamase Test- Objectives, Principle, Procedure and Results
Objective of X and V Factor Test To differentiate among Haemophilus species based on X and V factor required for growth. Principle of X and V Factor Test Haemophilus spp. have varying requirements for X and V growth factors. X factor indicates hemin and V factor indicates nicotinamide-adenine-dinucleotide, NAD. Consequently, the significant differences in growth factor … Read moreX and V Factor Test for Haemophilus
Objective of VP Test To differentiate two major types of facultative anaerobic enteric bacteria based on production of neutral products. Principle of VP Test Voges Proskauer test, commonly known as VP test is used to determine the ability of some organisms to produce neutral end products (e.g., 2, 3-butanediol or acetoin) from glucose fermentation. All members … Read moreVoges Proskauer (VP) Test
Objectives of PYR Test To determine the ability of organism to produce L-pyrrolidonyl arylamidase enzyme. It aids in the presumptive identification of group A streptococci (Streptococcus pyogenes) and Enterococci by the presence of the enzyme L-pyrrolidonyl arylamidase. Principle of PYR Test Pyrrolidonyl Arylamidase (PYR) test is a rapid test which is used for the presumptive identification … Read moreL-Pyrrolidonyl Arylamidase (PYR) Test