Bacteriological agar is the gelling agent used in virtually all solid culture media. Learn its properties, why it's preferred over gelatin, melting and solidification temperatures,...
A complete guide to in-house culture media preparation — weighing, dissolving, autoclaving, pH verification, dispensing, drying, and storage — with a troubleshooting table for comm...
The litmus milk test differentiates bacteria by four reactions: acid, alkaline, litmus reduction, and clot or peptonization. Learn each reaction, stormy fermentation in Clostridium...
A batch of agar that passes every visual check can still distort the exact reaction it's supposed to reveal. The real difference between a visual inspection and genuine quality con...
Deoxycholate Citrate Agar (DCA) is a selective and differential medium for isolating Salmonella and Shigella from stool. Learn its three-layer selectivity mechanism, colony morphol...
Selenite broth is the most widely used enrichment medium for isolating Salmonella from stool, urine, and food. Learn its principle, why selenite inhibits coliforms, preparation wit...
Bismuth Sulfite Agar is the most sensitive medium for isolating Salmonella Typhi from stool. Learn its bismuth sulfite mechanism, characteristic black rabbit-eye colonies with meta...
SS agar is a highly selective medium for Salmonella isolation from stool but despite its name, it inhibits most Shigella strains. Learn its principle, brilliant green mechanism, co...
The original general-purpose culture medium nearly every richer medium on this site is built from, why clinical labs mostly moved on to tryptic soy agar, and where nutrient agar is...
Why an unpigmented, unremarkable-looking colony from a CF sputum sample can still turn out to be Pseudomonas aeruginosa, and the one temperature test that separates it from its flu...
CLED (Cystine-Lactose-Electrolyte-Deficient) agar is the preferred single medium for urine culture. Learn its composition, why it inhibits Proteus swarming, colony colors of key ur...
Hektoen Enteric (HE) Agar is a selective and differential medium for Salmonella and Shigella with better Shigella recovery than SS agar. Learn its green-medium principle, three-car...
Culture media for Salmonella typhi and paratyphi
BCYE agar is the only medium that grows Legionella pneumophila, requiring L-cysteine and iron for growth. Learn its six-component principle, why charcoal is essential, how growth o...
Chocolate agar is an enriched medium for isolating fastidious pathogens like Haemophilus and Neisseria. Learn its composition, preparation, CO₂ requirement, colony morphology, and...
