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Biochemistry

CREATININE SINGLE REAGENT

CREATININE(Modified Jaffe’s Liquid Reagent):- INTENDED USE The reagent kit is intended for the in-vitro quantitative determination of creatinine in serum and urine. SUMMARY Creatinine is excreted as a waste product by the kidneys. Increased serum creatinine levels usually indicate impairment of renal function. It is commonly measured to evaluate kidney function and muscle metabolism. PRINCIPLE Creatinine in alkaline medium reacts with picric acid to form an orange coloured complex.The intensity of colour formed is directly proportional to the amount of creatinine present in the sample. REAGENTS Creatinine Reagent Creatinine Standard: 2 mg/dL MATERIALS REQUIRED BUT NOT PROVIDED Clean dry glassware Micropipettes & tips Laboratory timer Colorimeter / Spectrophotometer PREPARATION OF REAGENT & STABILITY The reagent kit is stable at 2–8°C till expiry date. Once opened, store reagent properly. PROCEDURE Tube Reagent Sample Standard Blank 1.0 ml – – Standard 1.0 ml – 100 µl Test 1.0 ml 100 µl – Mix well and record absorbance of test (AT) and standard (AS) at 510 nm. CALCULATION For Serum Creatinine (mg/dL) = ATAS×2 For Urine Creatinine (mg/dL) = ATAS×2×50frac{AT}{AS} times 2 times 50   NORMAL VALUES Serum: Male 0.6 – 1.5 mg/dL, Female 0.4 – 1.4 mg/dL Urine: Male 15 – 20 mg/kg/day, Female 8 – 15 mg/kg/day PRECAUTIONS Do not freeze reagents Bring reagents to room temperature before use Use clean and dry glassware Follow standard laboratory safety precautions

Biochemistry

CHOLESTROL

Cholestrol(CHOD / POD METHOD) INTENDED USE This reagent is intended for the in-vitro quantitative determination of cholesterol in human serum. PRINCIPLE Cholesterol esters are hydrolyzed by cholesterol esterase to free cholesterol and fatty acids.Free cholesterol is oxidized by cholesterol oxidase to cholestenone and hydrogen peroxide.Hydrogen peroxide reacts with 4-aminoantipyrine and phenol in presence of peroxidase to form a red coloured quinoneimine dye. REACTION Cholesterol Ester + H₂O → Cholesterol + Fatty acidsCholesterol + O₂ → Cholestenone + H₂O₂H₂O₂ + Phenol + 4-aminoantipyrine → Red quinoneimine REAGENTS Cholesterol Enzyme Reagent Cholesterol Standard (200 mg/dL) SPECIMEN :- Serum / Plasma PROCEDURE Tube Reagent Sample Standard Blank 1.0 ml – – Standard 1.0 ml – 10 µl Test 1.0 ml 10 µl – Mix well, incubate at 37°C for 5 minutes.Read absorbance at 505 nm against reagent blank. CALCULATION Cholesterol (mg/dL) = Abs(Test)Abs(Standard)×200frac{Abs(Test)}{Abs(Standard)} times 200 Abs(Standard)Abs(Test)×200 NORMAL VALUE Total Cholesterol: Less than 200 mg/dL CLINICAL SIGNIFICANCE Cholesterol is the main lipid found in blood. It is an essential structural component of cell membranes and is involved in the synthesis of steroid hormones and bile acids. Elevated cholesterol levels are associated with atherosclerosis and increased risk of coronary heart disease. STORAGE   Store reagent at 2–8°C. Do not freeze.

Biochemistry

Amylase kit

Amylase Kit(Direct Substrate Method):- INTENDED USE:- This diagnostic reagent kit is intended for in-vitro quantitative determination of amylase activity in human serum or plasma. PRINCIPLE Amylase catalyzes the hydrolysis of a 2-chloro-4-nitrophenyl linked substrate. The rate of hydrolysis is proportional to amylase activity in the sample. REACTION CNPG₃ + Amylase → CNP + G₃ + G₄ CONTENT Reagent-1 / Amylase Reagent MATERIALS REQUIRED BUT NOT PROVIDED Clean & dry glassware Laboratory glass pipettes / micropipettes & tips Bio-Chemistry Analyzer SAMPLES Serum free from hemolysis, heparinized plasma, or EDTA plasma. Specimen should be tested as fresh as possible. PROCEDURE Pipette into clean labeled test tubes: Component Blank Sample Working Reagent 1000 µl 1000 µl Sample — 20 µl Mix well and read the absorbance after 1, 2 & 3 minutes.Calculate the mean absorbance per minute (ΔA/min). CALCULATION OF RESULTS Amylase Activity (U/L) = ΔA/min × 3178 NORMAL VALUE Serum Amylase: Up to 100 U/L at 37°C CLINICAL SIGNIFICANCE Amylase is secreted by the pancreas into the duodenum. It catalyzes the hydrolysis of starch into sugars. Measurement of amylase activity is useful in the diagnosis of pancreatic disorders such as acute pancreatitis, pancreatic cancer, and pancreatic duct obstruction. GENERAL SYSTEM PARAMETERS Reaction Type Kinetic Wavelength 405 nm Temperature 37°C Delay 60 sec Incubation 60 sec Reaction 60 sec Sample Vol. 20 µl Reagent Vol. 1000 µl LIMITATIONS AND PRECAUTIONS Use non-hemolyzed samples Avoid contamination Do not use turbid or lipemic samples Do not freeze reagents QUALITY CONTROL Run normal and pathological controls with each assay.

SGPT (ALT) Test
Biochemistry

SGPT

SGPT INTENDED USE:This reagent kit is intended for in-vitro quantitative determination of SGPT (ALT) activity in serum. PRINCIPLE:SGPT (ALT) catalyzes the transfer of amino group between L-alanine and α-ketoglutarate to form pyruvate and glutamate. The pyruvate formed reacts with NADH in the presence of Lactate Dehydrogenase (LDH) to form lactate and NAD. The rate of oxidation of NADH to NAD is measured as a decrease in absorbance which is proportional to the SGPT (ALT) activity in the sample. REACTION:Alanine aminotransferaseL-Alanine + α-Ketoglutarate → Pyruvate + L-Glutamate Lactate DehydrogenasePyruvate + NADH + H⁺ → Lactate + NAD⁺ CONTENTS:Reagent 1: SGPT Enzyme ReagentReagent 2: SGPT Substrate Reagent MATERIALS REQUIRED BUT NOT PROVIDED:• Clean & Dry Glassware• Micropipettes & Tips• Bio-Chemistry Analyzer SAMPLES:Serum free of hemolysis. SGPT (ALT) is reported to be stable in serum for 3 days at 2–8°C. PROCEDURE:Pipette into clean dry test tubes as (T): Addition sequence Blank Test Working Reagent 1000 µl 1000 µl Sample — 100 µl Mix well and read the initial absorbance after 1 min and repeat the absorbance reading after every 1 min. Calculate the mean absorbance change per minute (ΔA/min). CALCULATION:SGPT activity (U/L) = ΔA/min × 1746

Potassium
Biochemistry

POTASSIUM

POTASSIUM (Monotest) BEACON INTENDED USE: This reagent kit is intended for the in-vitro quantitative determination of Potassium in Serum. PRINCIPLE: Potassium reacts with sodium tetraphenyl boron in a specially prepared buffer to form a colloidal suspension. The amount of turbidity produced is directly proportional to the concentration of potassium in the sample. CONTENTS: Reagent 1: Potassium Reagent Reagent 2: Potassium Standard 5 mEq/L SAMPLE COLLECTION AND PRESERVATION: Separate serum from the clot as soon as possible as potassium may leach from red blood cells which can elevate results. REAGENT PREPARATION AND STORAGE: All reagents are ready to use. Temperature: 25–30°C. PROCEDURE: Pipette into cuvettes labeled as Blank (B), Standard (S), and Test (T). Addition Sequence B S T Potassium Reagent 1.0 ml 1.0 ml 1.0 ml Standard — 20 µl — Sample — — 20 µl Mix well and incubate at RT for 5 mins. Measure the absorbance of Standard and Test against reagent blank at 630 nm. CALCULATION: Concentration of Potassium (mEq/L) = (Abs. T / Abs. S) × 5 NORMAL VALUES: 3.5 – 5.5 mEq/L Each laboratory should establish its own normal range. GENERAL SYSTEM PARAMETERS: Reaction type: End point Wavelength: 630 nm Cuvette: 1 cm Reaction temperature: Room temperature Zero setting: Reagent blank Sample volume: 10 µl Reagent volume: 1.0 ml Incubation time: 5 mins Standard concentration: 5 mEq/L REAGENT SYSTEM STABILITY: Reagents are stable until the expiration date mentioned on the label. LINEARITY: The procedure is linear up to 7 mEq/L.If values exceed this limit, dilute the sample with distilled water and multiply results with dilution factor. NOTES: As potassium is widely distributed, care should be taken to avoid contamination. All glassware should be free from alkali to avoid falsely high values. BIBLIOGRAPHY: Tietz NW, Fundamentals of Clinical Chemistry, W.B. Saunders Co., Philadelphia Henry RF et al., Clinical Chemistry Principles and Techniques David A. Sacks et al., Tietz Textbook of Clinical Chemistry Trinder, P., Ann. Clin. Biochem., 1969 (6: 159) QUALITY CONTROL: It is recommended that controls be included in each set of assays.

Biochemistry

LDL CHOLESTROL

LDL CHOLESTEROL DIRECT REAGENT KITBEACON INTENDED USE: The reagent kit is intended for the in-vitro quantitative determination of LDL Cholesterol in Serum / Plasma. PRINCIPLE: Cholesterol is released from LDL particles and enzymatically determined. Cholesterol Ester + H₂O(Cholesterol esterase) → Cholesterol + Fatty acids Cholesterol + O₂(Cholesterol oxidase) → Cholest-4-en-3-one + H₂O₂ H₂O₂ + 4-Aminoantipyrine + Phenol(Peroxidase) → Quinoneimine dye + H₂O The intensity of the colored complex formed is proportional to the LDL cholesterol concentration and is measured at 575 nm. REAGENTS: Reagent 1 (R1): Buffer Reagent 2 (R2): Enzymes Standard: LDL Cholesterol MATERIALS REQUIRED BUT NOT PROVIDED: Semi auto / Fully auto analyzer Micropipettes & Tips Incubator Distilled water SAMPLE: Serum or plasma. Avoid hemolysis. PROCEDURE (37°C): Blank Standard Sample Reagent 375 µl 375 µl 375 µl Standard — 25 µl — Sample — — 25 µl Mix and incubate for 5 minutes at 37°C.Measure absorbance at 575 nm against reagent blank. CALCULATION: LDL-C (mg/dl) = (Abs. of Test / Abs. of Standard) × Standard concentration NORMAL VALUES: < 130 mg/dl : Desirable 130–159 mg/dl : Borderline high ≥ 160 mg/dl : High risk of CHD Each laboratory should establish its own reference range. CLINICAL SIGNIFICANCE: LDL particles are lipoproteins that transport cholesterol to tissues. LDL cholesterol is considered a major risk factor for coronary heart disease and atherosclerosis. Elevated LDL levels are associated with increased risk of cardiovascular disease. PREPARATION OF REAGENT & STABILITY: Mix R1 and R2 as per instructions. Working reagent is stable for 7 days at 2–8°C. LINEARITY: The procedure is linear up to 1000 mg/dl.Samples exceeding this value should be diluted with normal saline (NaCl 0.9%) and retested. INTERFERENCES: No interference observed up to: Hemoglobin: 500 mg/dl Bilirubin (conjugated): 40 mg/dl Bilirubin (unconjugated): 40 mg/dl Ascorbic Acid: 5 mg/dl Triglycerides: 1000 mg/dl                 BIBLIOGRAPHY:- NCEP ATP III Guidelines Burtis & Ashwood, Tietz Fundamentals of Clinical Chemistry Other standard clinical chemistry references

Biochemistry

SGOT

SGOT(SERUM GLUTAMIC OXALOACITIC TRANSAMINASE) INTENDED USE:This reagent kit is intended for in vitro quantitative determination of SGOT (AST) activity in serum. PRINCIPLE:SGOT (AST) catalyzes the transfer of amino group between L-Aspartate and α-ketoglutarate to form oxaloacetate and glutamate. The oxaloacetate formed reacts with NADH in the presence of Malate Dehydrogenase to form NAD. The rate of oxidation of NADH to NAD is measured as a decrease in absorbance which is proportional to the SGOT (AST) activity in the sample. REACTION: L-Aspartate + α-Ketoglutarate—(Aspartate aminotransferase)→Oxaloacetate + Glutamate Oxaloacetate + NADH—(Malate Dehydrogenase)→L-Malate + NAD⁺ CONTENTS:Reagent 1: SGOT Enzyme ReagentReagent 2: SGOT Substrate Reagent MATERIALS REQUIRED BUT NOT PROVIDED: Clean & Dry Glassware Laboratory Glass Pipettes or Micropipettes & Tips Bio-Chemistry Analyzer SAMPLES:Serum free of hemolysis. SGOT (AST) is reported to be stable in serum for 3 days at 2–8°C. PROCEDURE:Pipette into clean dry test tube labeled as (T): Addition sequence (T) Working Reagent 1 ml Sample 100 µl Mix well and read the initial absorbance A₁ at 1 min and repeat the absorbance reading after every 1 & 2 mins. Calculate the mean absorbance change per minute (ΔA/min.). CALCULATION:SGOT activity (U/L) = ΔA/min × 1746 NORMAL VALUE:Serum: < 40 U/LEach laboratory should establish its own normal range representing patient population. CLINICAL SIGNIFICANCE:SGOT is an enzyme found mainly in heart muscle, liver cells, skeletal muscle and kidneys. Injury to these tissues results in the release of the enzyme into blood. Elevated levels are found in myocardial infarction, cardiac operations, hepatitis, cirrhosis, acute renal diseases, primary muscle diseases. Decreased levels may be found in pregnancy, beri beri and diabetic ketoacidosis. GENERAL SYSTEM PARAMETERS: Reaction Type: Kinetic (Decreasing) Wavelength: 340 nm Cuvette Temp: 37°C Delay Time: 60 sec Interval Time: 60 sec No. of Reading: 2 Reagent Volume: 1 ml Sample Volume: 100 µl Zero Setting: Deionised Water Light Path: 1 cm Factor: 1746 LINEARITY:The procedure is linear up to 300 U/L. If the activity exceeds this limit, dilute the sample with normal saline (NaCl 0.9%) and multiply result by dilution factor. QUALITY CONTROL:For accuracy it is necessary to run known controls with every assay. LIMITATION & PRECAUTIONS: Storage conditions as mentioned on the kit to be adhered. Do not freeze or expose the reagents to higher temperature as it may affect the performance of the kit. Before the assay bring all the reagents to room temperature. Avoid contamination of the reagent during assay process. Use clean glassware free from dust or debris.                          PREPARATION OF REAGENT & STABILITY: Working reagent:Mix 4 parts of Reagent 1 with 1 part of Reagent 2. Working solution is stable for 4 days at 2–8°C.

Microbiology

GRAM STAIN

GRAM STAIN :- Objective :- To differentiate bacteria into Gram-positive and Gram-negative based on the ability of their cell wall to retain the primary stain (crystal violet) after decolorization. Principle Gram-positive bacteria: Thick peptidoglycan layer → retain crystal violet–iodine complex → appear purple. Gram-negative bacteria: Thin peptidoglycan, high lipid content → lose crystal violet on decolorization → take up safranin → appear pink/red. Materials Required Clean glass slides Inoculating loop / needle Bunsen burner Staining rack Wash bottle with water Blotting paper Reagents Crystal Violet (Primary stain) Gram’s Iodine (Mordant) Decolorizer (Acetone–alcohol or 95% ethanol) Safranin (Counterstain) Procedure 1. Preparation of Smear Clean the slide and label it. Place a small drop of water on the slide. Pick a small amount of culture and spread to form a thin smear. Air dry completely. Heat fix by passing the slide over flame 2–3 times (do not overheat). ·         2. Gram Staining Steps Step Reagent Time   1 Crystal Violet 1 minute 2 Wash gently — 3 Gram’s Iodine 1 minute 4 Wash gently — 5 Decolorizer (Alcohol/Acetone) Few seconds (5–15 sec) 6 Wash immediately — 7 Safranin 30–60 seconds 8 Final wash — 9 Blot dry — Microscopic Examination Observe under oil immersion (100x) objective. Findings Gram-positive → Purple / violet Gram-negative → Pink / red Note shape: cocci, bacilli, spirilla, clusters, chains, pairs.

Biochemistry, Uncategorized

HDL CHOLESTROL

HDL CHOLESTEROL DIRECT REAGENT KIT BEACON INTENDED USE: The reagent is intended for the direct in-vitro quantitative determination of HDL cholesterol in human serum. PRINCIPLE: The direct HDL cholesterol assay is a homogeneous method for directly measuring serum HDL. Using selective detergents and enzymatic reaction, HDL cholesterol is measured without interference from LDL, VLDL and chylomicrons. The cholesterol esterase and cholesterol oxidase react with HDL cholesterol to form a colored quinoneimine dye whose intensity is proportional to the HDL cholesterol concentration. Reaction: HDL-C + Esterase → Cholesterol + Fatty acidsCholesterol + Oxidase → Cholestenone + H₂O₂H₂O₂ + Chromogen → Colored quinoneimine CONTENTS: Reagent 1: R1 Reagent 2: R2 Standard: HDL Cholesterol Calibrator MATERIALS REQUIRED BUT NOT PROVIDED: Laboratory glassware Micropipettes & tips Autoanalyzer / Semi-auto analyzer STORAGE AND STABILITY: The reagents are stable up to the expiry date stated on the label when stored at 2–8°C. Do not freeze. SAMPLES: Serum, Plasma (Heparin) PREPARATION OF REAGENTS & STABILITY: The reagent is ready to use. Calibrator: Reconstitute with distilled water. Let stand for 10 minutes, mix gently. Working reagent is stable for 7 days at 2–8°C. PROCEDURE: Blank Calibrator Sample R1 Reagent 450 µl 450 µl 450 µl Calibrator — 5 µl — Sample — — 5 µl R2 Reagent 150 µl 150 µl 150 µl Mix and incubate at 37°C for 5 minutes. Measure absorbance at 578 nm against reagent blank. CALCULATION: HDL-C    =  Abs of Sample/ Abs of Calibrator      ×Calibrator concentration NORMAL VALUE: Male: ≥ 40 mg/dL Female: ≥ 50 mg/dL (Values may vary depending on population and laboratory.) CLINICAL SIGNIFICANCE: Lipoproteins are particles with many transport fats in blood plasma. There are two groups: low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol. LDL cholesterol is mainly triglycerides, though LDL is also transport some amount of cholesterol. LDL causes cholesterol to be deposited in blood vessels and cause atherosclerosis. HDL cholesterol removes cholesterol from blood and transports it back to the liver for excretion. HDL is considered “good cholesterol” as higher levels are associated with lower risk of heart disease. Estimation of HDL cholesterol is useful for the risk assessment of coronary heart disease. GENERAL SYSTEM PARAMETERS: Reaction Type: End point Wavelength: 578 nm (540–620 nm) Temperature: 37°C Reaction Volume: R1 450 µl + R2 150 µl Sample Volume: 5 µl Measuring: Against blank Linearity: 5–150 mg/dL Calibration: Single point Reaction Time: 5 minutes LINEARITY: This procedure is linear up to 150 mg/dL. If values exceed this limit, dilute the sample with saline and repeat the assay. QUALITY CONTROL: Use recommended commercial quality control sera with each run. Results should fall within acceptable limits.

Microbiology

CULTURE MEDIA INTRODUCTION &PREPARATION

INTRODUCTIONOF CULTURE MEDIA Most bacteria can be cultured artificially on culture media containing required nutrients, pH and osmotic pressure. The microorganisms grow in an atmosphere and temperature most suited to their metabolic reactions. The pathogens are isolated in pure culture so that they can be identified and tested for their sensitivity to antimicrobials. The specimens are cultured in known volumes, and the number of bacterial colonies appearing after incubation can be counted. Operation room requirements and blood from blood bank are frequently checked for sterility by using pure culture methods. Vaccines and antitoxins require the growing of bacteria under controlled conditions. Stock cultures are also useful for the teaching institutes for practical training purposes. COMPOSITION OF CULTURE MEDIA The basic ingredients, which are common to the many of the frequently used media are as follows: 1.  Water: It allows fluids to enter and leave cells more readily and to enhance the chemical reactions. 2.Sodium chloride: Presence of sodium chloride maintains the isotonicity  of bacterial cells. 3.Peptones: It is a source of readily available nitrogen. 4.Buffers: They maintain a constant pH in culture media. 5.Indicators:  In culture media the indicators are useful in the detection of acid or alkali production by microorganisms. Indicators such as phenol red, methyl red and Bromocresol purple are used to adjust pH of the culture media. 6.  Solidifying agents: Agar, gelatin, egg yolks and serum are used as solidifying agents of the culture media. 7.Selective agents: These are special chemicals introduced into the culture media for inhibiting some types of bacteria, while allowing other bacteria to grow. Examples: (a) Crystal violet inhibits Staphylococci but not tubercle bacilli (b) 6.5% (w/ v) sodium chloride is inhibitory to most Streptococci but not S. faecalis. 8.   Additive for enrichment: The substances such as sheep blood, horse blood, rabbit serum or calf’s ground hearts allow fastidious organisms to grow since these organisms, may not survive in ordinary culture media. 9.Reducing substances: The substances such as thioglycollate are used to remove free oxygen from the medium for the growth of anaerobic bacteria. THE DIFFERENT TYPES OF CULTURE MEDIA Basic Media These support the growth of microorganisms that do not have special nutritional requirements. They are often used (a) To maintain stock cultures of control strains of bacteria and (b) For subculturing pathogens from selective media prior to performing biochemical and serological dentification tests. Examples: (1) Nutrient agar (2) Nutrient broth. Enriched Media These are enriched with (a) Whole blood (b) Lysed blood (c) Serum (d) Extra peptones and (e) Vitamins to support the growth of particular pathogens such as Hemophilus influenzae, Neisseria and Streptococcus species. Examples: (I) Blood agar (II) Tryptone soya media. Selective Media These media contain substances that accelerate the growth of required pathogens only and prevent or slow down the growth of other microorganisms. Example: XLD agar: It is used for the growth of Salmonellae and Shigellae. The bile salts present in this media inhibit the growth of many fecal commensals Differential (Indicator) Media These contain indicators, dyes or other substances which help to differentiate microorganisms. Example: TCBS agar contains the indicator bromothymol blue which differentiates sucrose fermenting from non-sucrose fermenting vibrio species. Transport Media When specimens are not cultured soon after collection, to prevent overgrowth and also to ensure survival of pathogens, transport media are used. These are mainly used to transport microbiological specimens from health centers to the district pathological laboratories. Example: (1) Amies transport medium (2) Cary Blair medium. DIFFERENT FORMS OF CULTURE MEDIA:- 1.      Solid Culture Media This is used in petri dishes and in test tubes (slope cultures) and prepared by adding Solidifying agent  (1.0 – 1.5%) (w/v). Microorganisms grow on this and form colonies after multiplication. This helps to identify the organism. 2.    Semisolid Culture Media This is prepared by adding Solidifying agent (0.4-0.5%) (w/v) to a fluid medium. These are used mainly as transport media and for the testing of motility of the organisms. 3.   Fluid Culture Media These media are mainly used as biochemical testing media, blood culture media or the enrichment media. PREPARATION OF CULTURE MEDIA Most culture media are available commercially in readymade dehydrated form. It is less costly to use readymade media, since the ingredients are often required in small amounts but available in large quantities if purchased. Some of the chemicals are also difficult to obtain. To ensure good performance and reproducibility in the results the following must be  performed correctly- 1.     Weighing and dissolving of the ingredients 2.     Addition of heat sensitive material 3.     pH testing 4.     Dispensing and sterilization 5.     Sterility testing and quality control 6. Storage Note 1.      The heat sensitive ingredients such as blood or serum should be brought to room temperature and added when the medium has cooled to about 50°C. 2.      A fluid medium should be tested for accurate pH by using a narrow, range pH paper. 3.      For sterilizing culture media, it is necessary to use manufacturer’s instructions. The commonly used methods for sterilization are- a) Autoclaving (b) Steaming at 100°C and (c) Filtration. It is necessary to use correct temperature and correct length of time. Precautions:- 1.  Autoclaving is used to sterilize most agar and fluid media. 2. Steaming at 100°C: Media such as Cary Blair transport medium contain ingredients that would break down above 100°C. Steaming can be performed in an autoclave with a loose lid. 3.    Filtration: Serum and solutions containing carbohydrates, urea, etc. are heat sensitive and hence cannot be autoclaved. Hence, the media containing such substances are filtered to remove bacteria. 4. Sterility testing: Media in tubes and bottles: Incubate the entire batch at 37°C overnight. Contamination is indicated by appearance of turbidity in a fluid medium and growth on a solid medium. 5.  Control of media: Appropriate control species are used to inoculate slants or plates of the medium (quarter part). After overnight incubation, the cultures are examined for (a) Degree of growth (b) Size of colonies and (c) Other characteristics. 6.Storage of culture media: Dehydrated culture media and dry ingredients (agars, peptones, bile salts, etc.) can be stored at room temperature (25°C ± 5°C) in a cool and dry place, away from

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