Microbiology

Isolate Salmonella and Shigella from clinical specimens and foods with selective Thermo Scientific™ Oxoid™ XLD Agar (Dehydrated). The medium relies on xylose fermentation, lysine decarboxylation and production of hydrogen sulphide for the primary differentiation of shigellae and salmonellae from non-pathogenic bacteria. The careful addition of sodium desoxycholate inhibits the growth of coliforms without decreasing the ability to support shigellae and salmonellae.

XLD Agar (Dehydrated), Oxoid Composition

XLD Agar (Dehydrated), Oxoid Preparation:
Suspend 53g in 1 litre of distilled water. Heat with frequent agitation until the medium boils. DO NOT OVERHEAT. Transfer immediately to a water bath at 50°C. Pour into sterile Petri dishes as soon as the medium has cooled.

It is important to avoid preparing large volumes which will cause prolonged heating.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Isolate Salmonella and Shigella from clinical specimens and foods with selective Thermo Scientific™ Oxoid™ XLD Agar (Dehydrated). The medium relies on xylose fermentation, lysine decarboxylation and production of hydrogen sulphide for the primary differentiation of shigellae and salmonellae from non-pathogenic bacteria. The careful addition of sodium desoxycholate inhibits the growth of coliforms without decreasing the ability to support shigellae and salmonellae.

XLD Agar (Dehydrated), Oxoid Composition

XLD Agar (Dehydrated), Oxoid Preparation:
Suspend 53g in 1 litre of distilled water. Heat with frequent agitation until the medium boils. DO NOT OVERHEAT. Transfer immediately to a water bath at 50°C. Pour into sterile Petri dishes as soon as the medium has cooled.

It is important to avoid preparing large volumes which will cause prolonged heating.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Thermo Scientific™ Oxoid Standard Plate Count Agar (Plate Count Agar) is a standard medium corresponding to the APHA formulation used for milk, food and dairy products.

Standard Plate Count Agar (Plate Count Agar), Oxoid Composition

Standard Plate Count Agar (Plate Count Agar), Oxoid Preparation:
Suspend 23.5g in 1 litre of distilled water. Bring to the boil to dissolve completely. Dispense into bottles and sterilise by autoclaving at 121°C for 15 minutes.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared plates at 2-8°C.

Detect coliform organisms in water, waste water and dairy products with selective Thermo Scientific™ Oxoid™ Lauryl Tryptose Broth (Dehydrated), while conforming to the formula detailed by American Public Health Association. Lauryl Tryptose Broth is designed to promote a rich growth and copious gas production from small inocula of coliform organisms.

Lauryl Tryptose Broth, Oxoid Composition

Lauryl Tryptose Broth, Oxoid Preparation:
Dissolve 35.6g in 1 litre of distilled water and distribute into containers with fermentation tubes (Durham). Sterilise by autoclaving at 121°C for 15 minutes.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at room temperature.

Precautions
If stored at 2-8°C the broth will become cloudy or form a precipitate. This should clear at room temperature but gas formation is the criterion of growth not turbidity.

Grow and isolate aerobic and anaerobic organisms of the intestinal tract, which may require selective conditions to inhibit the growth of background organisms like Escherichia coli, with Thermo Scientific™ Oxoid™ Schaedler Anaerobe Agar. The presence of cysteine in the medium provides selectivity against Escherichia coli as cysteine has shown to have inhibitory effects on several enzymatic reactions of Escherichia coli in vitro.¹

Schaedler Anaerobe Agar, Oxoid Composition

Schaedler Anaerobe Agar, Oxoid Preparation:
Suspend 40g in 1 litre of distilled water and boil to dissolve the medium completely. Sterilise by autoclaving at 121°C for 15 minutes. Mix well before pouring.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Prepared plates may be stored at 2-8°C if suitably protected.

Isolate and differentiate Shigella and Salmonella spp. from enteric pathological specimens with Thermo Scientific™ Oxoid™ Hektoen Enteric Agar (Dehydrated). Hektoen Enteric Agar was developed by King and Metzger. When compared to other selective media this medium gives higher yield of Salmonella and Shigella, while inhibiting accompanying Gram-positive and other microorganisms.

Hektoen Enteric Agar, Oxoid Composition

Hektoen Enteric Agar, Oxoid Preparation:
Suspend 76g of the medium in 1 litre of distilled water and soak for 10 minutes. Heat gently and allow to boil for a few seconds to dissolve the agar. DO NOT AUTOCLAVE. Cool to 50°C and pour plates.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared plates at 2-8°C.

Precautions
Do not overheat the medium or hold it molten for long periods. Proteus species may resemble salmonellae or shigellae.
Further testing must be carried out to confirm the presumptive identification of organisms isolated on this medium.

A medium specially designed to give large, clear zones with all antibiotics, without the addition of lysed or whole blood.

Sensitest Agar, Oxoid Composition

Sensitest Agar, Oxoid Preparation:
Suspend 32g in 1 litre of distilled water and bring to the boil to dissolve the agar. Sterilise by autoclaving at 121°C for 15 minutes.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared plates of agar at 2-8°C.

Precautions
As with other susceptibility testing media, Sensitest Agar should be used for rapidly growing aerobic organisms only. It should not be modified by the addition of carbohydrates or incubated in a CO2 enriched atmosphere.
If the medium is used for Bell’s CDS method then the specified discs and technique must be used. Refer to the monograph cited in the References.

Perform effortless Antimicrobial Susceptibility Testing (AST) using Thermo Scientific™ Oxoid™ Mueller Hinton Agar (Dehydrated), a medium designed and manufactured according to the European standard, EUCAST and the American standard, CLSI.

Composition of Mueller Hinton Agar, Oxoid

Preparation of Mueller Hinton Agar, Oxoid
Add 38g of Mueller Hinton Agar to 1 litre of distilled water. Bring to the boil to dissolve the medium completely. Sterilize by autoclaving at 121°C for 15 minutes.

Storage conditions and Shelf life:
Store the dehydrated Mueller Hinton Agar, Oxoid at 10-30°C and use before the expiry date on the label.
Store the prepared Mueller Hinton Agar plates at 2-8°C.

Precautions
Incubation in a carbon dioxide enriched atmosphere is not recommended because of its pH effect on the medium. If it is imperative to use CO₂ then known control organisms should be included with the test plates to measure its effect.
Carbohydrates should not be added to Mueller-Hinton Agar because they may influence the rate of growth of the organism and the resulting pH of the medium.
The addition of lysed horse blood to the medium may further reduce the levels of thymidine and prevent the growth of thymidine-dependent organisms.

The medium may not support the growth of some fastidious strains for example microorganisms that require thymine and thymidine for growth. Close adherence to the methodology is required to obtain satisfactory results.

Mueller Hinton Broth, Oxoid conforms to international standards for antimicrobial susceptibility testing media.

Mueller Hinton Broth, Oxoid Preparation
Place 21.0g of Mueller Hinton Broth, Oxoid in 1 litre of distilled water mix to dissolve completely. Sterilize by autoclaving at 121°C for 15 minutes. Chill and adjust cation levels if necessary.

Storage conditions and Shelf life
Store the dehydrated Mueller Hinton broth at 10-30°C and use before the expiry date on the label.
Store the prepared Mueller Hinton broth at 2-8°C.

Precautions
Monitor the performance of the broth routinely using the standard QC organisms. If the broth does not yield the expected MIC values, modify the volumes of Mg++ and Ca++ solutions.

If the thymidine content is lowered, after the addition of lysed horse blood or thymidine phosphorylase, the MIC values may be lower.

• Oxoid Mycoplasma Broth Base is used for the selective isolation of Mycoplasma species.
• Also available Mycoplasma Supplement G, Part No. SR0059C.

Mycoplasma Broth Base, Oxoid Composition

Mycoplasma Broth, Oxoid Preparation:
Dissolve 25.5g in 1 litre of distilled water. Mix well and distribute in 80ml volumes. Sterilise by autoclaving at 121°C for 15 minutes. Cool to approximately 50°C and add one vial of Mycoplasma Supplement SR0059 reconstituted as directed.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Precautions
Thallous acetate is toxic, observe the precautions stated under Hazards section..
Sub-culture the broth to agar as soon as any indicator added begins to change colour before the pH change destroys the organism.

• Oxoid Mycoplasma Agar Base is used for the selective isolation of Mycoplasma pneumoniae.
• Also available Mycoplasma Supplement P, Part No. SR0060C and Mycoplasma Supplement G, Part No. SR0059C.

Mycoplasma Agar Base, Oxoid Composition

Mycoplasma Agar, Oxoid Preparation:
Add 35.5g to 1 litre of distilled water. Boil to dissolve the agar and distribute in 80ml volumes. Sterilise by autoclaving at 121°C for 15 minutes. Cool to approximately 50°C and add one vial of Mycoplasma Supplement SR0059 reconstituted as directed.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Precautions
Thallous acetate is toxic, observe the precautions in the HAZARDS section.
Do not use thallous acetate media to isolate Ureaplasma urealyticum.
Mycoplasmas may be suspected if (1) typical morphology (2) no growth in media without serum (3) colonies are embedded below the agar surface.

Enrich and isolate Salmonella from feces and food products with Thermo Scientific™ Oxoid™ Selenite Broth Base (Lactose).The presence of Selenium in the medium provides selectivity against non-target bacteria.

Selenite Broth Base (Lactose), Oxoid Composition

Selenite Broth Base (Lactose), Oxoid Preparation:
Dissolve 4g of sodium biselenite LP0121 in 1 litre of distilled water and then add 19g of Selenite Broth Base. Warm to dissolve, mix well and fill out into containers. Sterilise in a boiling water bath, or in free flowing steam, for 10 minutes. DO NOT AUTOCLAVE.

To minimise any possible risk of teratogenicity to laboratory workers, the sodium biselenite must be added as a solution to this medium.
Robertson1 reported miscarriages and possible teratogenic effects on pregnant laboratory assistants which may have been caused by ingested sodium biselenite. Oxoid therefore removed this substance from the powdered medium.

Although no further reports have been received sodium biselenite is now considered to be very toxic and should be handled with great care.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C away from light.

Precautions
Discard the prepared medium if large amounts of reduced selenite can be seen as a red precipitate in the bottom of the bottles.
Do not incubate longer than 24 hours because the inhibitory effect of selenite is reduced after 6-12 hours incubation.
Take sub-cultures of broth from the upper third of the broth column, which should be at least 5 cm in depth.

DCLS Agar is a modified form of Desoxycholate Citrate Agar which includes sucrose in its formulation. The addition of this fermentable carbohydrate increases the usefulness of the medium because non-pathogenic sucrose-fermenting organisms may be recognised by their red colonies, e.g. some Proteus, Enterobacter and Klebsiella species.

DCLS Agar, Oxoid Composition

DCLS Agar, Oxoid Preparation:
Suspend 50g in 1 litre of distilled water. Bring to the boil to dissolve the medium. Cool to 50°C and pour into sterile Petri dishes.
DO NOT AUTOCLAVE.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared agar plates at 2-8°C.

Precautions
Boil the medium for the minimal period of time to get the agar into solution. Overheating reduces the agar gel strength and increases the degree of inhibition. It is therefore important not to hold the molten medium at 50°C for more than the short time required to distribute it into dishes.

Thioglycollate Medium USP – Alternative, is intended for sterility testing with certain biological products that are turbid or otherwise do not lend themselves readily to culturing in Thioglycollate Medium USP (CM0173) because of its viscosity.

Thioglycollate Medium USP – Alternative, Oxoid Composition

Thioglycollate Medium USP – Alternative, Oxoid Preparation:
Suspend 29g in 1 litre of distilled water. Bring to the boil and dissolve the medium completely. Distribute into tubes or bottles and sterilise by autoclaving at 121°C for 15 minutes.
PREPARE FRESHLY OR BOIL AND COOL THE MEDIUM JUST BEFORE USE.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.

Whilst storage of the prepared medium is not recommended, autoclaved volumes of Thioglycollate Medium USP – Alternative, should be held at 20-30°C in the dark. Storage at lower temperatures increases oxygen absorption.

Precautions
This medium lacks agar and reducing indicator, therefore it is essential that the medium is freshly prepared and used within four hours of preparation.
Thioglycollate media should not be reheated more than once because toxic oxygen radicles are formed on reheating.

Detect salmonellae including Salmonella arizonae with the diagnostic Thermo Scientific™ Oxoid™ Lysine Iron Agar (Dehydrated). This differential medium detects salmonellae (including lactose fermenting Salmonella arizonae) by lysine decarboxylase activity and H₂S production.

Lysine Iron Agar, Oxoid Composition

Lysine Iron Agar, Oxoid Preparation:
Suspend 34g in 1 litre of distilled water. Bring to the boil to dissolve completely. Dispense into tubes and sterilise by autoclaving at 121° C for 15 minutes. Cool the tubes in an inclined position to form slants with deep butts.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8° C.

Detect and enumerate enterococci from water and food samples with Thermo Scientific™ Slanetz and Bartley Medium (Dehydrated). Slanetz and Bartley originally devised this medium to detect and enumerate enterococci by the technique of membrane filtration, but it has also proved useful as a direct plating medium. The medium is very selective for enterococci and, when it is incubated at elevated temperatures (44-45°C), all red or maroon colonies may be accepted as presumptive enterococci.

Slanetz and Bartley Medium (Dehydrated), Oxoid Composition

Slanetz and Bartley Medium Preparation:
Suspend 42g in 1 litre of distilled water and bring to the boil to dissolve the agar completely.

EXCESSIVE HEATING MUST BE AVOIDED. Dispense into Petri dishes and allow to solidify. It should not be remelted. The medium may be used with membrane filters or by spreading dilutions of the sample over the surface of the agar with a glass rod.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C away from light.

Precautions
Count all red, maroon or pink colonies as presumptive enterococci. Not all species reduce TTC therefore pale colonies should not be ignored.
Although incubation at 35°C yields a higher count, it allows the growth of organisms which do not conform to the definition of enterococci. Incubation at 44-45°C has a selective effect and produces fewer false-positives. However, the preliminary incubation at 35°C encourages the recovery of stressed organisms.
Although the selective properties of this medium are very good it is advisable to regard the colony count as a presumptive or unconfirmed count. Further identification may be required depending on the scope of the examination.

Selectively isolate Neisseria species with Thermo Scientific™ Oxoid™ GC Agar Base (Dehydrated). GC Agar Base has been formulated to include Special Peptone LP0072 which is a mixture of meat and plant enzymatic digests. The presence of starch in the medium ensures that toxic metabolites produced by Neisseria are absorbed. Phosphate buffers are included to prevent changes in pH due to amine production that would affect the survival of the organism

GC Agar Base, Oxoid Composition

Oxoid MRS Agar (de Man, Rogosa, Sharpe) (Dehydrated) is used for the growth of Lactobacilli.

Composition of MRS Agar, Oxoid

Preparation of MRS Agar, Oxoid

Suspend 62g of your MRS Agar in 1 litre of distilled water. You can boil to dissolve the powder completely. After a dissolve, you can sterilise the medium by autoclaving at 121°C for 15 minutes.

Storage Conditions and Shelf Life of MRS Agar, Oxoid

You can store your dehydrated MRS Agar at 10-30°C and use before the expiry date on the label. You can store the prepared plates at 2-8°C.

Isolate and enumerate lactic acid bacteria from food with Thermo Scientific™ Oxoid™ MRS Broth (DeMan, Rogosa and Sharpe) (Dehydrated). This non-selective medium is designed to support profuse growth of lactic acid bacteria.

MRS Broth (DeMan, Rogosa and Sharpe), Oxoid Composition

MRS Broth (DeMan, Rogosa and Sharpe), Oxoid Preparation:
Add 52g to 1 litre of distilled water at approximately 60°C. Mix until completely dissolved. Dispense into final containers and sterilise by autoclaving at 121°C for 15 minutes.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Oxoid Muller-Kauffmann Tetrathionate Broth Base is selective enrichment medium for isolation of Salmonella spp. and suppression of Proteus species.

Muller-Kauffmann Tetrathionate Broth Base, Oxoid Composition

Muller-Kauffmann Tetrathionate Broth, Oxoid Preparation:
Suspend 82g in 1 litre of distilled water and bring to the boil. Cool below 45°C and add, just prior to use, 19ml of iodine solution and 9.5ml of a 0.1% brilliant green solution. Mix well and fill out into sterile tubes or flasks.

Dissolve the potassium iodide in approximately 5ml of distilled water, add the iodide and gently warm the solution to completely dissolve it. Make up the volume to 100ml with distilled water.

Add the brilliant green to the distilled water and shake to dissolve the dye. Heat the solution to 100°C for 30 minutes and shake from time to time whilst cooling, to ensure that the dye has completely dissolved. Store in a brown glass bottle or away from light.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Precautions
Do not autoclave the base broth.
Add the iodine solution and brilliant green just prior to use.
The medium is not suitable for the growth of Salmonella typhi, Salmonella sendai, Salmonella pullorum and Salmonella gallinarum.

Selectively isolate pathogenic Vibrio species with Thermo Scientific™ Oxoid™ TCBS (Thiosulfate Citrate Bile Salts Sucrose) Cholera Medium (Dehydrated). The medium has shown to be the most satisfactory and reproducible formula regardless of the complex composition. Unlike Lauryl Sulphate Tellurite Agar it does not require further additives or aseptic additions of blood. It also possesses superior growth characteristics for Vibrio species, compared with tellurite media. While inhibiting non-vibrios, it promotes rapid growth of pathogenic vibrios after overnight incubation at 35°C.

TCBS (Thiosulfate Citrate Bile Salts Sucrose) Cholera Medium (Dehydrated), Oxoid Composition

TCBS (Thiosulfate Citrate Bile Salts Sucrose) Cholera Medium (Dehydrated), Oxoid Preparation:
Suspend 88g in 1 litre of distilled water. Boil to dissolve the medium completely. DO NOT AUTOCLAVE.
Pour plates without further heating and dry before use.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
Store the prepared medium at 2-8°C.

Precautions
The identification of the various Vibrio species on TCBS Medium is presumptive and further tests are required for confirmation.
Yellow colonies on TCBS Medium will give unsatisfactory oxidase reactions.
Colonies taken from TCBS Medium are `sticky’ and react poorly in slide agglutination tests. Subculture to nutrient agar is required before slide agglutination tests can be carried out.
Some strains of Vibrio vulnificus produce better recovery at 30°C.