Part of Thermo Fisher Scientific
Organisms this product works with:
Other products used in the isolation of Staphylococcus sp:
An anaerobic enrichment broth for Staphylococcus aureus.
pH 6.9 ± 0.2 @ 25°C
Suspend 54.2g in one litre of distilled water and heat gently to dissolve. Dispense 19ml amounts into 20 x 200mm test tubes and sterilise by autoclaving at 121°C for 15 minutes. Cool rapidly then aseptically add to each tube 0.3ml of a sterile solution of Potassium tellurite 3.5% SR0030.
The medium requires the addition of a 3.5% solution of Potassium tellurite when there is a direct addition of 1g of the sample to 19mls of broth. This level of Potassium tellurite is necessary to suppress the high numbers of contaminating organisms that could be expected.
The use of a diluted solution of Potassium tellurite is applicable when a 1 in 10 dilution of the food sample is carried out1. In such cases the SR0030 should first be diluted 1 in 10 with sterile distilled water.
The addition of 0.1% Tween 80 can be recommended in order to improve recovery of heat injured Staphylococcus aureus cells e.g. from milk powder. 1g of Tween 80 should be added to 1 litre of CM0523 prior to autoclaving2.
Oxoid Giolitti-Cantoni Broth, a tellurite-mannitol-glycine enrichment broth, based on the formulation of Gott and Cantoni3 is used for the selection and enrichment of Staphylococcus aureus from foodstuffs. Mannitol and sodium pyruvate are growth stimulants for staphylococci and aid detection of the organism when present in small numbers only4.
The growth of Gram-negative lactose fermenting bacilli are inhibited by lithium chloride and Gram-positive bacilli are inhibited by Potassium tellurite in combination with glycine.
The creation of anaerobic conditions by overlaying with 2cm of sterile paraffin wax inhibits the growth of micrococci.
Giolitti-Cantoni Broth is recommended for the detection of Staphylococcus aureus in dried baby milk and other weaning foods where the organism should be absent from 1g of test material6.
The medium is suitable for the examination of meat and meat products7. For this purpose the concentration of the Potassium tellurite must be reduced to 0.35% and it is recommended that the weight of the test sample should be reduced to 0.1-0.01g.
The medium should be inoculated as soon as it has been cooled after autoclaving. If there is a delay in putting the medium to use it must be freed from dissolved air by immersion in free-flowing steam for 20 minutes.
Inoculate 1g of sample material and 1ml aliquots of a series of suitable decimal dilutions into tubes containing 19 ml of Giolitti-Cantoni Broth. Two tubes are used for the sample material and for each of the dilutions. This increases the likelihood of detecting Staphylococcus aureus when it is present in very small numbers.
The medium is overlaid with 2cm of molten sterile paraffin wax (melting temperature 42-44°C) and incubated for 48 hours at 35°C, examining daily. The result is considered negative for Staphylococcus aureus if no blackening of the medium is observed. If blackening does occur at the bottom of the tubes or general blackening of the medium, the broth is streaked on to a staphylococcal isolation medium, such as Baird-Parker Medium8 and incubated at 35°C for 24-48 hours. The result is considered positive if black colonies, with a narrow white margin, surrounded by a zone of clearing, are seen.
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.
Dehydrated medium: Straw coloured, free-flowing powder
Prepared medium: Straw coloured solution
Staphylococcus aureus ATCC® 25923*†
Turbid growth; blackening
1. IDF International Standard 60A:1978.
2. Chopin et al (1985) J. Food Prod. 48 No.1 21-27.
3. Giolitti C. and Cantoni C. (1966) J. Appl. Bact. 29. 395.
4. Baird-Parker A. C. (1962) J. Appl. Bact. 25. 12.
5. Lambin S. and German A. (1961) `Précis de microbiologic’ p.63, Paris Masson.
6. Mossel D. A. A., Harrewijn G. A. and Elzebroek J. M. (1973) UNICEF.
7. ISO/DIS 5551 (1177) Part 2.
8. De Waart J., Mossel D. A. A., Ten Broeke R. and Van de Moosdijk A. (1968) J. Appl. Bact. 31. 276.