All are true about culture media except
(A) (Mac- Conkey agar prevent growth of G-ve bacteria) (45, 46- Bevja 4th; 42-43- Ananthanarayan 9th)Mac-Conkev agar* Mainly used to differentiate between varius Gram negative rod shaped organisms* It is also used to inhibit growth of gram positive organism thus it is both differential and selective media.Mac-conkey medium which consists of peptone, lactose agar, neutral red and taurocholate shows up lactose fermenters as pink colonies while non-lactose fermenters are coloumess or pale. This may also be termed indicator medium.Composition and uses of Liquid MediaMediumCompositionUses1. Peptone waterPeptone - 1% Na Ci- 0.5%water- 100 ml (PH 7.4)Routine culture, sugar fermentation tests2. Nutrient brothPeptone water + Meat extract- 1 % 3. Glucose brothNutrient broth + Glucose- 0.5%Blood culture, culture of certain organisms e,g, Streptococci4. Enrichment media i) Alkaline peptone waterPeptone water (p H 9.0)Culture of vibrioii) Selenite F brothPeptone water, sodium seleniteCulture of faeces for salmonellae and shigellaeiii) Tetrathionate brothNutrient broth, sodium thiosulphate, calcium carbonate, iodine solutionCulture of faeces especially for salmonellaeiv) Cooked meat broth (CMB) Rebertson's cooked meat broth (RCM)Nutrient broth, predigested cooked meat of ox heartCulture of anaerobic bacteriaComposition and uses of Solid MediaMediumCompositionUses1. Simple medium i) Nutrient agarNutrient broth Agar (2-3%)Routine culture2. Enriched media i) Blood agarii) Chocolate agariii) Loeffler's serum slope (LSS)Nutrient agar, Sheep blood (5-10%)Heated blood agar (55degC X2 hr)Nutrient broth Glucose, Horse serumRoutine cultureCulture of Neisseria H, influenzaCulture of C diphtheria3. Indicator medium i) MacConkey's mediumPeptoneLactoseSodium taurocholateAgarNeutral redCulture of Gram negative bacilli4. Selective media i) Deoxycholate citrate agar (DCA)ii) Bile salt agar (BSA)Nutrient agar, Sodium deoxycholate, sodium citrate, Lactose, Neutral redNutrient agar, Sodium taurocholate (0.5%) pH 8.2Culture of salmonellae and ShigellaeCulture of vibrio choleraKEY POINTS1. Culture media are required to grow the organisms from infected material to identify the causative agent2. The basic constituents of culture media are water, electrolyte, peptone, meat extract, blood or serum and agar.3. When basal medium is added with some nutrients such as blood, serum of egg, it is called enriched medium.4. Some substances are incorporated in the liquid medium which have a stimulating effect on the bacteria and be growth or inhibits the competitors. Such media are called enrichment media, e,g, selenite broth.5. Selective media contain substances that inhibit all but a few types of bacteria and facilitate the isolation of a particular species. Example is bite salt agar (BSA).6. Differential medium contains substances which help to distinguish differing characteristics of bacteria. Example is MacConkey's medium7. Indicator media contain an indicator which changes colour when bacterium grows in them. macConkey's medium is differential as well as an indicator medium8. Anaerobic media are used for cultivation of anaerobic bacteria, e,g, cooked meat broth (CMB
Mac-Conkey agar prevents growth of g- "ve"bacteria
Thayer- martin - gonococcus
LJ media - mycobacteria
Selenite F broth - salmonella
General