Microbiology

Oxoid Blood Agar Base is a nonselective general purpose medium which may be enriched with blood or serum.

Blood Agar Base, Oxoid Composition

Blood Agar Base, Oxoid Preparation:
Suspend 40g in 1 litre of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes.

For blood agar, cool the Base to 50°C and add 7% of Defibrinated Horse Blood SR0050. Mix with gentle rotation and pour into petri dishes or other containers.

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 medium at 2-8°C.

Precautions
The haemolytic reactions of organisms inoculated on to this medium will be affected by the animal blood used e.g. horse or sheep and the incubation conditions e.g. aerobic, capnoeic or anaerobic.
When horse blood is added to the medium Haemophilus haemolyticus colonies will produce beta-haemolysis and mimic Streptococcus pyogenes.

Oxoid Urea Agar Base (Christensen Agar Base) is used for detection of urease-producing microorganisms.

Urea Agar Base, Oxoid Composition

Urea Agar Preparation:
Suspend 2.4g in 95ml of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 115°C for 20 minutes. Cool to 50°C and aseptically introduce 5ml of sterile 40% Urea Solution SR0020. Mix well, distribute 10ml amounts into sterile containers and allow to set in the slope position.

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 alkaline reaction produced in this medium after prolonged incubation may not be caused by urease activity. Check using medium without urea.
Do not heat or reheat the medium because urea decomposes very easily.
For the detection of urease-positive Proteae the reaction must be read within the first 2-5 hours of incubation.

Oxoid MRVP Medium. A glucose-phosphate medium is used for the differentiation of the coli-aerogenes group by the Methyl Red and Voges-Proskauer tests.

MRVP Medium, Oxoid Composition

MRVP Medium, Oxoid Preparation:
Add 17g to 1 litre of distilled water. Mix well, distribute 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 2-6°C.

Precautions
The MR-VP reactions are only part of the tests required to identify organisms.
Each laboratory should standardise on the inoculum density, volume of broth and the test container size.
MR tests require a minimum incubation of 48 hours before the pH indicator is added.
When using Barritt’s reagents add a-naphthol first and KOH second; do not reverse this order.
Vaughn et al. warned of false positive VP reactions if the completed tests are left standing for over an hour.

Oxoid Desoxycholate Citrate Agar is a differential medium for enumeration of coliforms and the isolation of enteric pathogens.

Desoxycholate Citrate Agar, Oxoid Composition

Desoxycholate Citrate Agar, Oxoid Preparation:
Suspend 48.5g in 1 litre of distilled water. With frequent agitation bring to the boil over a gauze and flame to dissolve completely. Mix well and pour plates immediately. Dry the agar surface before use.

THIS MEDIUM IS HEAT SENSITIVE. AVOID EXCESSIVE OR PROLONGED HEATING DURING RECONSTITUTION. DO NOT AUTOCLAVE, OR REMELT.

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
The medium is best used freshly prepared.
Stock cultures of Shigella species may become predominantly in the R-phase when subcultured away from DCA media. Such cultures are difficult to use for control purposes without first heavily streaking the cultures on DCA plates and picking off the few S-phase colonies i.e. the macro-colonies on the agar surface, for further subculture.
When making biochemical tests on colonies picked from the surface of DCA plates, purity subcultures should be carried out because the colony may be contaminated with Escherichia coli present as micro-colonies.

Oxoid Kligler Iron Agar is used for differential identificaton of Enterobacteriaceae.

Kligler Iron Agar, Oxoid Composition

Kligler Iron Agar, Oxoid Preparation:
Suspend 55g in 1 litre of distilled water. Bring to the boil to dissolve completely. Mix well and distribute into containers. Sterilise by autoclaving at 121°C for 15 minutes. Allow to set as slopes with 1 inch 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.

Precautions
It is essential that Kligler Iron Agar is examined and reported at 18-24 hours. Early or late readings will give false results.
KIA will grow both oxidative and fermentative organisms. Confusion will result if care is not taken to distinguish between the two groups.
Always use a straight wire to inoculate the butt, to avoid splitting the agar with a loop.
Pure cultures are essential to avoid misinterpretation.
Do not use screw-capped tubes or bottles for KIA medium. It is essential that air is freely available to growth on the slant.

Oxoid Brilliant Green Bile Broth 2% is used for detection or confirmation of presence of members of coli-aerogenes group.

• Recommended for 44°C confirmatory test for Escherichia coli

Brilliant Green Bile Broth 2%, Oxoid Composition

Brilliant Green Bile Broth 2%, Oxoid Preparation:
Dissolve 40g in 1 litre of distilled water. Mix well, distribute into containers fitted with Durham’s tubes and sterilise by autoclaving at 121°C for 15 minutes.

Do not autoclave double stregnth medium. The alternative procedure is to heat the dissolved broth at 100°C for 30 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 tubes of broth at 2-8°C.

Precautions
Do not autoclave double-strength broth.
Gram-positive sporing organisms may produce gas if the bile/brilliant green inhibition is attenuated by food material.

Oxoid Tetrathionate Broth Base is used for selective enrichment of Salmonella species.

Tetrathionate Broth Base, Oxoid Composition
Add 77g to 1 litre of distilled water and bring to the boil. Cool below 45°C and add 20ml of iodine solution. Mix well and tube in 10ml quantities. The prepared base will keep for several weeks at 4°C but should be used soon after the addition of the iodine solution.

Iodine Solution

Tetrathionate Broth Preparation:
Tetrathionate Broth is recommended for the selective enrichment method of isolating Salmonella typhi and other salmonellae from faeces, sewage, etc.

Organisms which reduce tetrathionate, such as salmonellae, flourish in the medium whilst many faecal organisms are inhibited. Members of the Proteus group reduce tetrathionate and may consequently impair the value of this medium for the isolation of salmonellae; this disadvantage of the medium is largely overcome by the addition of 40µg of novobiocin to each millilitre of the incomplete medium before the addition of iodine.

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 (without iodine solution) at 2-8°C.

Oxoid Edwards Medium, Modified is used for selective isolation of Streptococcus agalactiae.

Edwards Medium, Modified, Oxoid Composition

Edwards Medium, Modified, Oxoid Preparation:
Suspend 41g in 1 litre of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 115°C for 20 minutes. Cool to 50°C, add 5-7% of sterile bovine or sheep blood, mix well 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.

This product has been discontinued. The alternative product is Thioglycollate Fluid Medium USP (CM0173).

Oxoid Thioglycollate Medium, Brewer is an anaerobic medium especially useful for sterility control of solutions containing mercury-based preservatives.

Thioglycollate Medium, Brewer, Oxoid Composition

Thioglycollate Medium, Brewer, Oxoid Preparation:
Suspend 20g in 1 litre of distilled water. Bring to the boil, mix well and allow to stand until completely dissolved. Distribute into final containers and sterilise by autoclaving at 121°C for 15 minutes.

Media containing small quantities of agar are liable to separate if cooled rapidly. Tubes of reconstituted and autoclaved medium should be allowed to cool slowly on a wooden surface in a draught-free atmosphere.

Storage conditions and Shelf life
Store the dehydrated medium at 10-30°C and use before the expiry date on the label.
The prepared medium should be stored away from light at room temperature.

Precautions
Check the upper portion of the prepared medium before inoculation. If more than one-third of the fluid is oxidised i.e. green coloured, discard the bottle.

If one-third or less fluid is oxidised, then heat in boiling water with the cap loosened to drive off oxygen. Cool to room temperature before inoculation. This reheating process can only be carried out once because of the formation of toxic radicles in the medium.

Organisms which ferment glucose and lower the pH to critical levels may not survive in this medium after growth has taken place.

Oxoid Milk Agar, Oxoid is for use in the dairy industry.

Milk Agar, Oxoid Composition

Milk Agar, Oxoid Preparation:
Suspend 24g in 1 litre of distilled water. Bring to the boil to dissolve completely. 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.

Carry out plate counts of microorganisms in water with Thermo Scientific™ Oxoid™ Yeast Extract Agar (Dehydrated). Yeast Extract Agar is made to the formula described by Windle Taylor for the plate count of microorganisms in water and is tested in accordance with ISO 1133:2014. It is a rich, nutritious medium for the recovery of a wide range of bacteria, yeast, and molds.

Yeast Extract Agar, Oxoid Composition

Yeast Extract Agar, Oxoid Preparation:
Suspend 23g in 1 litre of distilled water. Bring to the boil to dissolve completely. 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 Lab-Lemco Broth is a nutrient medium equivalent to USA nutrient extract formulations.

Lab-Lemco Broth, Oxoid Composition

Lab-Lemco Broth, Oxoid Preparation:
Dissolve 8g in 1 litre of distilled water and distribute into final containers. 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.
`Lab-Lemco’ Broth is slightly more alkaline than the medium used in the APHA publications (pH 6.8).

MacConkey agar, Oxoid is used to detect, isolate and enumerate coliforms and intestinal pathogens in water, dairy products and biological specimens. This differential medium gives a number of diagnostic indications such as bile tolerance, colony morphology and chromogenesis. MacConkey Agar corresponds to the medium recommended by the World Health Organizaton, the Department of Health for the bacterial examination of water.

Composition of MacConkey Agar (Oxoid)

Preparation of MacConkey Agar (Oxoid):

Suspend 52g of MacConkey agar powder in 1 litre of distilled water. Bring to the boil to dissolve completely. Sterilise by autoclaving at 121°C for 15 minutes.

Storage conditions and Shelf life of MacConkey Agar (Oxoid)
Store the dehydrated MacConkey agar powder at 10-30°C and use before the expiry date on the label.
Store the prepared MacConkey agar at 2-8°C.

Identify coliforms from water and milk samples with differential Thermo Scientific™ Oxoid™ MacConkey Broth (Dehydrated). MacConkey Broth is the standard medium for the primary isolation of coliform bacteria, and has been recommended for this purpose by the Public Health Laboratory Service Water Committee and the World Health Organization. MacConkey Broth also conforms to the formulation specified by the UK Dept. of Health for milk grading.

MacConkey Broth, Oxoid Composition

MacConkey Broth, Oxoid Preparation:
To prepare single strength broth, add 40g to 1 litre of distilled water. Mix well and distribute into containers fitted with fermentation (Durham) tubes. 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.

Precautions
The neutral red indicator is carefully selected for this formulation and therefore shows no inhibitory effect. However, the more sensitive reaction of bromocresol purple in MacConkey Broth Purple (CM0505) is often preferred.

Oxoid Nutrient Agar Tablets make 5mL of medium each.

Nutrient Agar Tablets, Oxoid Composition

Nutrient Agar, Oxoid Preparation:
Add one tablet to 5ml of distilled water and soak for 5 minutes. 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 MUG Supplement (50mg) Fluorescent agent is used for the detection of E. coli.

• Contains 4-methylumbelliferyl-β-D-glucuronide (MUG)
• Each vial supplements 500mL of medium

M.U.G. Supplement, Oxoid Composition

M.U.G. Supplement, Oxoid Preparation:

Add 2ml of distilled water to a vial and invert gently until completely dissolved. Add the vial contents to the following volumes of suggested media, before sterilisation.

Storage conditions and Shelf life
Should be stored at 2-8°C. When stored as directed the unopened vial is stable until the expiry date on the label.

Precautions
The presence of endogenous glucuronidase in shellfish samples may result in false positive fluorescence. Test tubes used in the MPN method should be checked under UV light to ensure the glass does not fluoresce. To avoid false positive fluorescence the source of long wave UV light must not exceed 6 watts.

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Oxoid Saline Tablets is used for preparation of 500mL of 0.85% isotonic saline. For Laboratory Use Only.

Oxoid Ringers Solution Tablets is used for the preparation of isotonic diluents for bacterial cells and bacteriological specimens.

Each tablet prepares 500mL solution. For Laboratory Use Only.

Ringers Solution Tablets, Oxoid Composition

One tablet makes 500 ml of quarter-strength Ringers solution.

Ringers Solution Preparation:
To prepare quarter-strength Ringers Solution, dissolve 1 tablet in 500ml of distilled water. Sterilise by autoclaving at 121°C for 15 minutes.

Oxoid Basic Fuchsin Indicator is a dye for use with Endo Agar Base, Part No. CM0479B and m Endo (LES) Agar Base, Part No. MM0551B.

Basic Fuchsin Preparation:

BR0050 should be dissolved to create a 10% w/v solution using 95% ethyl alcohol.

For each litre of culture medium use the amount described in the product reconstitution details.  This should be in a 10% w/v solution of the dye dissolved in 50:50 ethanol/distilled water.  E.g. For CM0479 add 6ml of a 10% w/v Basic Fuchsin solution per litre of medium.

The magenta dyes are closely related to known carcinogenic substances; therefore basic fuchsin should be handled with care, avoiding inhaling the powder or staining the skin with dye.

• Oxoid Thiosulphate Ringers Tablets is used for preparation of isotonic diluents for bacterial cells and bacteriological specimens.
• Each tablet prepares 500mL solution.

Thiosulphate Ringers Tablets, Oxoid Composition

* Due to the low ionic content of this medium no pH is specified.
One tablet makes 500ml of quarter-strength Ringer containing 0.05% of sodium thiosulphate.

Thiosulphate Ringers Tablets, Oxoid Preparation:
To prepare quarter-strength Ringer Solution containing thiosulphate, dissolve 1 tablet in 500ml distilled water. Sterilise by autoclaving at 121°C for 15 minutes.