X and V factor Test – Principle, Procedure, Uses and Interpretation

X and V factor Test

Haemophilus spp are small, pleomorphic, gram-negative bacilli or coccobacilli with random arrangements. A clinically important species of the genus, influenzaeis a fastidious organism which grows best at 35-37°C with ~5% CO2  and in the presence of special accessory growth factors called X and V factors. X factor … Read more

SXT Test – Principle, Procedure, Uses and Interpretation

SXT Test

Although bacitracin susceptibility has routinely been used for the presumptive identification of group A streptococci, it has been observed that streptococcal groups vary in their susceptibilities to Taxo A (bacitracin, 0.04 units) and SXT (trimethoprim [1.25 mg] plus sulfamethoxazole [23.75 mg],) disks. Group A beta … Read more

Pyruvate Broth Test – Principle, Procedure, Uses and Interpretation

Pyruvate Broth Test

Biochemical tests are the tests used for the identification of bacterial species based on the differences in the biochemical activities of different bacteria. Bacterial physiology differs from one type of organism to another. The ability of bacteria to form organic compounds by metabolizing certain carbohydrates … Read more

ONPG Test – Principle, Procedure, Uses and Interpretation

ONPG Test

The ability of bacteria to ferment lactose depends on two enzymes, permease and beta-galactosidase. Permease allows lactose to enter the bacterial cell wall, where it is then broken down into glucose and galactose by beta-galactosidase. The glucose and galactose can then be metabolized by the bacteria. … Read more

Novobiocin Susceptibility Test – Principle, Procedure, Uses and Interpretation

Novobiocin Susceptibility Test

Novobiocin is an aminocoumarin antibiotic, produced by the actinomycete Streptomyces nivens, with antibacterial property. In 1975, Kloos and Schleifer reported a simplified scheme for differentiating coagulase-negative Staphylococcus spp. which included a novobiocin disk test. Staphylococcus saprophyticus, a gram positive coagulase negative Staphylococci, is an uropathogenic bacterium that causes … Read more

MUG Test – Principle, Procedure, Uses and Interpretation

MUG test

It has been reported that the enzyme β-glucuronidase is present in most strains of E. coli (97%).Organisms other than E. coli (e.g., Salmonella, Shigella, Staphylococcus, Streptococcus, etc.) also possess the enzyme β-glucuronidase. Hence, the detection of the β-glucuronidase enzyme is commonly employed in laboratories to … Read more

Motility Test – Principle, Procedure, Uses and Interpretation

Motility Test

Motility is the ability of an organism to move by itself by means of propeller-like flagella unique to bacteria or by special fibrils that produce a gliding form of motility. Motile  bacteria  move  using   flagella, thread like  locomotor  appendages  extending  outward  from  the plasma … Read more

Microdase Test – Principle, Procedure, Uses and Interpretation

Microdase Test

Microdase Disk is a reagent-impregnated disk recommended for use in qualitative procedures to aid in the differentiation of Staphylococcus from Micrococcus by the detection of the oxidase enzyme. The oxidase method was originally described by Kovacs in 1956 as a method of differentiating gram-negative bacilli. … Read more

Malonate Test – Principle, Procedure, Uses and Interpretation

Malonate Test

Malonate test is a colorimetric test of the ability of bacteria to use malonate as a source of carbon, the endpoint of which is the production of alkaline metabolites that induce a color change. Objectives To test the ability of the organism to utilize malonate as sole source of carbon and energy for growth. To differentiate organisms on the basis of malonate utilization. Principle An organism that simultaneously can utilize sodium malonate as … Read more

Lipid Hydrolysis Test – Principle, Procedure, Uses and Interpretation

Lipid Hydrolysis Test

Lipids are high-molecular-weight compounds possessing large amounts of energy. Once assimilated into the cell, they are metabolized through aerobic respiration to produce cellular energy, adenosine triphosphate (ATP). The components may also enter other metabolic pathways for the synthesis of other cellular protoplasmic requirements. However, before … Read more

Lecithinase Test – Principle, Procedure, Uses and Interpretation

Lecithinase Test

Phosphatidylcholine or simply, lecithin is a substance widely distributed in animal tissues, egg yolk, and some higher plants, consisting of phospholipids linked to choline. Some microorganisms possess lecithinase, also called phospholipase C, which is an enzyme that splits the phospholipid lecithin. Such lecithinase activity is used … Read more

Fermentation Test – Principle, Procedure, Uses and Interpretation

Fermentation Test

The ability of bacteria to form organic compounds by metabolizing certain carbohydrates and related compounds is a widely used method for the identification of microorganisms. Different fermentation media are used to differentiate organisms based on their ability to ferment carbohydrates incorporated into the basal medium. … Read more

Cetrimide Test – Principle, Procedure, Uses and Interpretation

Cetrimide Test

Cetrimide is a quaternary ammonium salt, which acts as a selective agent and inhibits most bacteria by acting as a cationic detergent (Cetyltrimethylammonium bromide). Cetrimide when added into a culture medium results into a selective solid medium recommended for use in qualitative procedures for selective … Read more

Bile Esculin Test – Principle, Procedure, Uses and Interpretation

Bile Esculin Hydrolysis Test

Esculin is a glycosidic coumarin derivative (6-beta-glucoside-7-hydroxy-coumarin). The two moieties of the molecule (glucose and 7-hydroxycoumarin) are linked together by an ester bond through oxygen. Many bacteria can hydrolyze esculin, but few can do so in the presence of bile. Thus the bile esculin test is … Read more

Butyrate Disk Test – Principle, Procedure, Uses and Interpretation

Butyrate Disk Test

Butyrate discs are employed in the microbiology lab for demonstrating the enzymatic hydrolysis of bromo-chloro-indolyl butyrate. The Test Disc is used for rapid detection and qualitative procedures of butyrate esterase for presumptive identification of Moraxella catarrhalis. Moraxella catarrhalis is recognized as a significant pathogen whose isolation … Read more