WO1996000794A1 - Method for rapid detection of certain salmonella species and equipment useful in the method - Google Patents
Method for rapid detection of certain salmonella species and equipment useful in the method Download PDFInfo
- Publication number
- WO1996000794A1 WO1996000794A1 PCT/HU1995/000031 HU9500031W WO9600794A1 WO 1996000794 A1 WO1996000794 A1 WO 1996000794A1 HU 9500031 W HU9500031 W HU 9500031W WO 9600794 A1 WO9600794 A1 WO 9600794A1
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- WIPO (PCT)
- Prior art keywords
- enrichment
- medium
- culture
- magnesium chloride
- temperature
- Prior art date
Links
- 238000000034 method Methods 0.000 title claims abstract description 23
- 241000607142 Salmonella Species 0.000 title claims description 22
- 238000001514 detection method Methods 0.000 title claims description 19
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L Magnesium chloride Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims abstract description 30
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000001963 growth medium Substances 0.000 claims abstract description 18
- 229910001629 magnesium chloride Inorganic materials 0.000 claims abstract description 15
- 239000002609 medium Substances 0.000 claims abstract description 14
- 239000001888 Peptone Substances 0.000 claims abstract description 11
- 108010080698 Peptones Proteins 0.000 claims abstract description 11
- 235000019319 peptone Nutrition 0.000 claims abstract description 11
- 238000002955 isolation Methods 0.000 claims abstract description 10
- HPQYKCJIWQFJMS-UHFFFAOYSA-L tetrathionate(2-) Chemical class [O-]S(=O)(=O)SSS([O-])(=O)=O HPQYKCJIWQFJMS-UHFFFAOYSA-L 0.000 claims abstract description 7
- 230000008569 process Effects 0.000 claims description 3
- 244000005700 microbiome Species 0.000 claims description 2
- 239000000243 solution Substances 0.000 description 21
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 9
- 238000011534 incubation Methods 0.000 description 7
- 235000013305 food Nutrition 0.000 description 6
- 229920001817 Agar Polymers 0.000 description 5
- 239000008272 agar Substances 0.000 description 5
- 239000012153 distilled water Substances 0.000 description 5
- 241000894006 Bacteria Species 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 3
- 230000002860 competitive effect Effects 0.000 description 3
- 210000003608 fece Anatomy 0.000 description 3
- 239000004615 ingredient Substances 0.000 description 3
- 229910052740 iodine Inorganic materials 0.000 description 3
- 239000011630 iodine Substances 0.000 description 3
- 244000005706 microflora Species 0.000 description 3
- PGSADBUBUOPOJS-UHFFFAOYSA-N neutral red Chemical compound Cl.C1=C(C)C(N)=CC2=NC3=CC(N(C)C)=CC=C3N=C21 PGSADBUBUOPOJS-UHFFFAOYSA-N 0.000 description 3
- UVTKHPSJNFFIDG-UHFFFAOYSA-L potassium tetrathionate Chemical compound [K+].[K+].[O-]S(=O)(=O)SSS([O-])(=O)=O UVTKHPSJNFFIDG-UHFFFAOYSA-L 0.000 description 3
- HAEPBEMBOAIUPN-UHFFFAOYSA-L sodium tetrathionate Chemical compound O.O.[Na+].[Na+].[O-]S(=O)(=O)SSS([O-])(=O)=O HAEPBEMBOAIUPN-UHFFFAOYSA-L 0.000 description 3
- AKHNMLFCWUSKQB-UHFFFAOYSA-L sodium thiosulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=S AKHNMLFCWUSKQB-UHFFFAOYSA-L 0.000 description 3
- 235000019345 sodium thiosulphate Nutrition 0.000 description 3
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 2
- 229930006000 Sucrose Natural products 0.000 description 2
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 2
- WQZGKKKJIJFFOK-VFUOTHLCSA-N beta-D-glucose Chemical compound OC[C@H]1O[C@@H](O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-VFUOTHLCSA-N 0.000 description 2
- 229940041514 candida albicans extract Drugs 0.000 description 2
- 235000013681 dietary sucrose Nutrition 0.000 description 2
- 230000003292 diminished effect Effects 0.000 description 2
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 235000013372 meat Nutrition 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 108010009004 proteose-peptone Proteins 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 230000007480 spreading Effects 0.000 description 2
- 238000003892 spreading Methods 0.000 description 2
- 230000001954 sterilising effect Effects 0.000 description 2
- 229960004793 sucrose Drugs 0.000 description 2
- 235000000346 sugar Nutrition 0.000 description 2
- 239000012138 yeast extract Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 206010022678 Intestinal infections Diseases 0.000 description 1
- GUBGYTABKSRVRQ-QKKXKWKRSA-N Lactose Natural products OC[C@H]1O[C@@H](O[C@H]2[C@H](O)[C@@H](O)C(O)O[C@@H]2CO)[C@H](O)[C@@H](O)[C@H]1O GUBGYTABKSRVRQ-QKKXKWKRSA-N 0.000 description 1
- BELBBZDIHDAJOR-UHFFFAOYSA-N Phenolsulfonephthalein Chemical compound C1=CC(O)=CC=C1C1(C=2C=CC(O)=CC=2)C2=CC=CC=C2S(=O)(=O)O1 BELBBZDIHDAJOR-UHFFFAOYSA-N 0.000 description 1
- 241000773293 Rappaport Species 0.000 description 1
- -1 Rappaport's Chemical compound 0.000 description 1
- 206010039438 Salmonella Infections Diseases 0.000 description 1
- 229940124639 Selective inhibitor Drugs 0.000 description 1
- 102000004142 Trypsin Human genes 0.000 description 1
- 108090000631 Trypsin Proteins 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000000987 azo dye Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 231100000433 cytotoxic Toxicity 0.000 description 1
- 230000001472 cytotoxic effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 201000010099 disease Diseases 0.000 description 1
- 208000037265 diseases, disorders, signs and symptoms Diseases 0.000 description 1
- 229910000397 disodium phosphate Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 235000013611 frozen food Nutrition 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000008101 lactose Substances 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- FDZZZRQASAIRJF-UHFFFAOYSA-M malachite green Chemical compound [Cl-].C1=CC(N(C)C)=CC=C1C(C=1C=CC=CC=1)=C1C=CC(=[N+](C)C)C=C1 FDZZZRQASAIRJF-UHFFFAOYSA-M 0.000 description 1
- 229940107698 malachite green Drugs 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 235000015097 nutrients Nutrition 0.000 description 1
- 229960003531 phenolsulfonphthalein Drugs 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000005180 public health Effects 0.000 description 1
- 206010039447 salmonellosis Diseases 0.000 description 1
- 229940082569 selenite Drugs 0.000 description 1
- MCAHWIHFGHIESP-UHFFFAOYSA-L selenite(2-) Chemical compound [O-][Se]([O-])=O MCAHWIHFGHIESP-UHFFFAOYSA-L 0.000 description 1
- 230000000405 serological effect Effects 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 239000002352 surface water Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000012588 trypsin Substances 0.000 description 1
- 230000035899 viability Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/02—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving viable microorganisms
- C12Q1/04—Determining presence or kind of microorganism; Use of selective media for testing antibiotics or bacteriocides; Compositions containing a chemical indicator therefor
- C12Q1/10—Enterobacteria
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2333/00—Assays involving biological materials from specific organisms or of a specific nature
- G01N2333/195—Assays involving biological materials from specific organisms or of a specific nature from bacteria
- G01N2333/24—Assays involving biological materials from specific organisms or of a specific nature from bacteria from Enterobacteriaceae (F), e.g. Citrobacter, Serratia, Proteus, Providencia, Morganella, Yersinia
- G01N2333/255—Salmonella (G)
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/30—Against vector-borne diseases, e.g. mosquito-borne, fly-borne, tick-borne or waterborne diseases whose impact is exacerbated by climate change
Definitions
- the invention relates to a method and equipment for detection of certain Salmonella species.
- Salmonella bacteria may induce an intestinal infection called salmonellosis in human.
- the detection of the bacterium is routinely carried out: from the faeces of ill men (in some cases from that of bacteria-defecating persons); from the consumed foodstufis causing the disease; from food-products presumably containing Salmonella bacteria as well as from water (drink water, surface-water or sewage).
- the detection of presence of Salmonella is a work of great importance from the view ⁇ point of medical diagnosis as well as public health and commerce of food-products. In the latter case, presence of Salmonella in a food implies the prohibition of putting it into circulation, too.
- Salmonella is presumably high), ii) selective enrichment, iii) isolation and iv) identification.
- the isolation is the most circuitous and, at the same time, the most unreliable step in the methods of detection of Salmonellae.
- the steps of pre-enrichment and enrichment are aimed to increase the cell-count of Salmonella of the test sample introduced to a suitable liquid medium and, simultaneously, to diminish the cell-count of the competitive microflora.
- the pre-enrichment is achieved by incubation in a buffered peptone solution (so-called peptone water), which comprises: peptone 10.0 g sodium chloride 5.0 g disodium hydrogen phosphate 9.0 g distilled water 1000.0 ml
- enrichment media for the detection of Salmonellae appropriate enrichment media are e.g. those containing tetrathionate salts (such as M ⁇ ller-Kauffinan's solution, Bierbrauer's solution); those containing magnesium chloride/Malachite Green (e.g. Rappaport's, Rappaport-Vassiliadis 1 media); various selenite-containing enrichment media (e.g. selenite-cysteine medium for the examination of faeces) and the like. These nutrient media contain also selective inhibitors impeding the growth of Salmonellae to a certain extent, too.
- tetrathionate salts such as M ⁇ ller-Kauffinan's solution, Bierbrauer's solution
- magnesium chloride/Malachite Green e.g. Rappaport's, Rappaport-Vassiliadis 1 media
- selenite-containing enrichment media e.g. selenite-cy
- the isolation is accomplished by one or more spreadings on agar plates of selective culture-media, such as Brilliant Green/Phenol Red/lactose agar (e.g. Edel-Kampelmacher's agar), which are aimed to obtain the highest number of well-isolated colines being then distinguished on the basis of morphology of colonies and the colour reaction developed. Subsequently, after transoculation to a novel plates, the colonies developed are further cultivated and then identified by using biochemical and serological methods.
- selective culture-media such as Brilliant Green/Phenol Red/lactose agar (e.g. Edel-Kampelmacher's agar)
- Hungarian patent No. 194,302 discloses a culture-medium plate and a method for the efficient isolation of Salmonella species, the said plate and method being different from the above-mentioned plates and methods.
- the invention disclosed in the said patent is based on the recognition that Brilliant Green, being a cytotoxic azo dye, inhibits the growth of all present bacteria including Salmonellae and the competitive microflora whereas magnesium chloride, when added to the medium, acts as a specific detoxicant for Salmonella species. Therefore, Salmonella colonies appear on the plate in spite of the concentration of Brilliant Green which is higher than usual (0.02 - 0.03 g/1; and even 0.04 g/1 according to the last experiments).
- the detection of Salmonellae is commonly accomplished in special, well-equipped laboratories where, on the one hand, the pre-enrichment and enrichment, respectively, are effectuated at different temperatures and, on the other hand, the cultivation of the inoculated culture-media is carried out at two incubation temperatures. Thus, separate incubators are required for the different temperatures.
- a drawback of the known methods consits in that they are circuitous and labour- intensive because of several transoculations, furthermore, require numerous equipments because of the separate incubators used for various incubation temperatures. In addition, the transfer of a test material from one incubator into an other demands additional work input.
- the invention is based on the recognition that even the pre-enrichment medium can be made selective to a certain extent when it contains a tetrathionate salt; thus, the pre- enrichment and enrichment can quasi be combined and a direct transoculation from the pre- enrichment medium onto the isolating plate can convenienty be performed. Furthermore, the invention is based on the recognition that the equipment- and work-demand of the method can be diminished by carrying out the incubation in a single apparatus capable for adjusting to and for switching over between two temperature values.
- the invention relates to a method for the rapid detection of certain Salmonella species.
- a solution consisting of buffered peptone water supplemented with a tetrathionate salt is used as pre-enrichment enrichment medium and the isolation is preferably accomplished on a culture-medium plate containing Brilliant Green and magnesium chloride.
- the tetrathionate salt used in the pre-enrichment enrichment medium may be potassium tetrathionate or sodium tetrathionate in situ obtained from sodium thiosulfate with iodine dissolved in potassium iodide solution.
- Potassium tetrathionate is used in an amount of 15-25 g/1, preferably 20 g/1; sodium tetrathionate obtained in situ is employed in an equivalent amount to that of potassium tetrathionate.
- the isolation is accomplished on a culture-medium plate containing Brilliant Green and magnesium chloride.
- the Salmonella-negativity of a sample can safely be declared.
- the usual process of isolation and identification should be carried out.
- a Brilliant Green magnesium chloride plate disclosed in the Hungarian patent No. 194,302.
- This medium comprises: meat extract 1.5-3.5 g peptone 4.0-6.0 g Na 2 HPO 4 and NaH 2 PO 4 0.25-0.50 g yeast extract 0.5- 1.5 g
- the pre-enrichment or enrichment, respectively, as well as the growth of the inoculated culture-media can be performed in the equipment according to the invention.
- the invention also relates to an equipment used in the rapid detection of certain
- the euipment is an incubator fitted with a water jacket (1), wherein the temperature of air capacity (2) can be adjusted to two temperature values, e.g. 37 °C and 43 °C, respectively.
- Two temperature-sensing devices (3) built in and the electric temperature- controlling device (4) connected thereto are provided for the adjustment and control of the temperature. Switching over between the two temperature values can be achieved by the means of a three-way switch (5), the positions of which are: (i) switched-off state, (ii) e.g. 37 °C, and (iii) e.g. 43 °C.
- the equipment is fitted with a time-switch (6), too; thus, the moment of switching-on of the equipment or the switching over from a temperature value to an other one can be pre-adjusted.
- the sample put into the pre-enrichment/enrichment medium is placed into the air capacity of the incubator and kept there overnight.
- a transoculation onto isolating plates is carried out, then the plates are put again into the air capacity of the incubator adjusted to 43 °C.
- the plates are evaluated and, if necessary, the detection is continued in a known manner by transoculation onto an additional differentiating culture-medium.
- the time demand of the detection of Salmonella has been significantly decreased by using the pre-enrichment/enrichment containing tetrathionate salt in combination with the culture-medium plates containing Brilliant Green and magnesium chloride.
- An additional advantage of this combination lies in that it can be used for detecting a cell count as low as 10 3 /ml, whereas the usual methods give no reliable results below a cell count of 10 s -10 6 /ml. Furthermore, it has been found that an approximate estimation of the number of colonies can be made by carrying out the transoculation with a calibrated inoculating loop.
- the equipment according to the invention is useful not only for the detection of Salmonella but also for any other biological cultivations.
- the invention is illustrated by the following non-limiting Examples.
- the chemical reagents used are products of analytical grade of the Merck Company.
- Preparation of a pre-enrichment medium A sterile, buffered peptone water was prepared by dissolving the following ingredients in 1000 ml of distilled water: casein peptone digested by trypsin 10.0 g sodium chloride 5.0 g
- sodium thiosulfate solution of 50 w/v% was prepared and sterilized at 121 °C. Additionally, 20.0 g of iodine and 25.0 g of potassium iodide were dissolved in water and filled up to 100 ml.
- a base culture-medium was prepared from the following ingredients: meat extract 3.0 g casein peptone 5.0 g yeast extract 1.0 g
- a mixture solution was prepared from the following ingredients: Brilliant Green solution of 0.5 w/v% 6.0 ml
- a previously sterile-filtered stock solution was prepared from magnesium chloride, from which the amount required was portionwise added to the mixture solution.
- the mixture solution was sterile-filtered through a bacterium filter.
- Culture-medium plates were prepared by mixing 900 ml of base culture-medium solution heated to 50 °C with 100 ml of mixture solution similarly heated to 50 °C, the pH was adjusted to 7.0-7.2, then the solution was poured into Petri dishes to form plates.
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- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
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- Wood Science & Technology (AREA)
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Abstract
The method of the invention comprises using a peptone solution supplemented with tetrathionate salt as pre-enrichment or enrichment medium, respectively, and carrying out isolation on a culture-medium plate containing Brilliant Green and magnesium chloride. The equipment comprises an air capacity (2) surrounded by a water jacket (1) and is fitted with at least one temperature-sensing device (3), electric control device (4) for controlling the temperature as well as a three-way switch (5) and a time switch (6).
Description
METHOD FOR RAPID DETECΗON OF CERTAIN SALMONELLA SPECIES AND AN EQUIPMENT USEFUL IN THE METHOD
The invention relates to a method and equipment for detection of certain Salmonella species. Salmonella bacteria may induce an intestinal infection called salmonellosis in human.
The detection of the bacterium is routinely carried out: from the faeces of ill men (in some cases from that of bacteria-defecating persons); from the consumed foodstufis causing the disease; from food-products presumably containing Salmonella bacteria as well as from water (drink water, surface-water or sewage). The detection of presence of Salmonella is a work of great importance from the view¬ point of medical diagnosis as well as public health and commerce of food-products. In the latter case, presence of Salmonella in a food implies the prohibition of putting it into circulation, too.
Numerous methods are known for the safe detection of Salmonella species from food- products and water, respectively, which are, however, circuitous and may require even ten days in some cases. The declaration of Salmonella-negativity of some food-products demands a particularly long time. Within this, the examination of dried products and quick- frozen foods is even more lengthy since here biologically damaged bacteria with diminished viability occur which, at first, need to be made capable for cultivation. The detection of Salmonellae is carried out in three or four steps: i) non-selective pre-enrichment (this step may be omitted when the cell-count of
Salmonella is presumably high), ii) selective enrichment, iii) isolation and iv) identification.
Biologically, the isolation is the most circuitous and, at the same time, the most unreliable step in the methods of detection of Salmonellae.
The steps of pre-enrichment and enrichment are aimed to increase the cell-count of Salmonella of the test sample introduced to a suitable liquid medium and, simultaneously, to diminish the cell-count of the competitive microflora. The pre-enrichment is achieved by incubation in a buffered peptone solution (so-called peptone water), which comprises: peptone 10.0 g sodium chloride 5.0 g
disodium hydrogen phosphate 9.0 g distilled water 1000.0 ml
Since no selective inhibiting substances are contained in the peptone water, not only Salmonellae but all other microorganisms, namely, the undesired competitive microflora also propagate in this medium. Thus, the detection of Salmonellae becomes difficult, even impossible in some cases.
Several types of solutions are known for enrichment; for the various test materials (water, food, faeces) various, enrichment media providing the most appropriate efficiency are used. According to standards, for the detection of Salmonellae appropriate enrichment media are e.g. those containing tetrathionate salts (such as Mϋller-Kauffinan's solution, Bierbrauer's solution); those containing magnesium chloride/Malachite Green (e.g. Rappaport's, Rappaport-Vassiliadis1 media); various selenite-containing enrichment media (e.g. selenite-cysteine medium for the examination of faeces) and the like. These nutrient media contain also selective inhibitors impeding the growth of Salmonellae to a certain extent, too.
The isolation is accomplished by one or more spreadings on agar plates of selective culture-media, such as Brilliant Green/Phenol Red/lactose agar (e.g. Edel-Kampelmacher's agar), which are aimed to obtain the highest number of well-isolated colines being then distinguished on the basis of morphology of colonies and the colour reaction developed. Subsequently, after transoculation to a novel plates, the colonies developed are further cultivated and then identified by using biochemical and serological methods.
Hungarian patent No. 194,302 discloses a culture-medium plate and a method for the efficient isolation of Salmonella species, the said plate and method being different from the above-mentioned plates and methods. The invention disclosed in the said patent is based on the recognition that Brilliant Green, being a cytotoxic azo dye, inhibits the growth of all present bacteria including Salmonellae and the competitive microflora whereas magnesium chloride, when added to the medium, acts as a specific detoxicant for Salmonella species. Therefore, Salmonella colonies appear on the plate in spite of the concentration of Brilliant Green which is higher than usual (0.02 - 0.03 g/1; and even 0.04 g/1 according to the last experiments). However, the above-mentioned effects can prevail only in the case when the incubation is carried out at an elevated temperature; at about 43 °C. Due to the high concentration of magnesium chloride used (12-16 g/1) only Salmonella colonies appear on the culture-medium during an overnight incubation. The appearing colonies are easy to
recognize since Neutral Red used as indicator changes its colour to striking yellow because of the pH alteration. This pH change is a consequence of acid formation from glucose or saccharose employed as carbon source in the culture-medium.
The detection of Salmonellae is commonly accomplished in special, well-equipped laboratories where, on the one hand, the pre-enrichment and enrichment, respectively, are effectuated at different temperatures and, on the other hand, the cultivation of the inoculated culture-media is carried out at two incubation temperatures. Thus, separate incubators are required for the different temperatures.
A drawback of the known methods consits in that they are circuitous and labour- intensive because of several transoculations, furthermore, require numerous equipments because of the separate incubators used for various incubation temperatures. In addition, the transfer of a test material from one incubator into an other demands additional work input.
Taking into consideration the above facts, it has been aimed to develop a method providing a more rapid and simple detection of certain Salmonella species. This task has been solved partly by improving the steps of enrichment and pre- enrichment, respectively, and partly by constructing a novel equipment.
The invention is based on the recognition that even the pre-enrichment medium can be made selective to a certain extent when it contains a tetrathionate salt; thus, the pre- enrichment and enrichment can quasi be combined and a direct transoculation from the pre- enrichment medium onto the isolating plate can convenienty be performed. Furthermore, the invention is based on the recognition that the equipment- and work-demand of the method can be diminished by carrying out the incubation in a single apparatus capable for adjusting to and for switching over between two temperature values.
Accordingly, the invention relates to a method for the rapid detection of certain Salmonella species.
According to the invention, a solution consisting of buffered peptone water supplemented with a tetrathionate salt is used as pre-enrichment enrichment medium and the isolation is preferably accomplished on a culture-medium plate containing Brilliant Green and magnesium chloride. The tetrathionate salt used in the pre-enrichment enrichment medium may be potassium tetrathionate or sodium tetrathionate in situ obtained from sodium thiosulfate with iodine dissolved in potassium iodide solution. Potassium tetrathionate is used in an
amount of 15-25 g/1, preferably 20 g/1; sodium tetrathionate obtained in situ is employed in an equivalent amount to that of potassium tetrathionate.
After overnight incubation of the test sample in this pre-enrichment/enrichment medium at a temperature of 37 °C, a transoculation is made onto an isolating plate and the usual detection procedure is continued.
According to a preferred embodiment of the process of the invention, the isolation is accomplished on a culture-medium plate containing Brilliant Green and magnesium chloride. In this way, the Salmonella-negativity of a sample can safely be declared. When the development of Salmonella colonies is observed on a plate containing magnesium chloride, the usual process of isolation and identification should be carried out.
It is preferred to use a Brilliant Green magnesium chloride plate disclosed in the Hungarian patent No. 194,302. This medium comprises: meat extract 1.5-3.5 g peptone 4.0-6.0 g Na2HPO4 and NaH2PO4 0.25-0.50 g yeast extract 0.5- 1.5 g
Brilliant Green 0.02-0.05 g
Neutral Red 0.02-0.03 g magnesium chloride 12.0-16.0 g sugars (saccharose, glucose) 3.3-5.5 g agar 12-15 g distilled water 1000 ml
The pre-enrichment or enrichment, respectively, as well as the growth of the inoculated culture-media can be performed in the equipment according to the invention. The invention also relates to an equipment used in the rapid detection of certain
Salmonella species.
This equipment is illustrated in Figure 1.
The euipment is an incubator fitted with a water jacket (1), wherein the temperature of air capacity (2) can be adjusted to two temperature values, e.g. 37 °C and 43 °C, respectively. Two temperature-sensing devices (3) built in and the electric temperature- controlling device (4) connected thereto are provided for the adjustment and control of the temperature. Switching over between the two temperature values can be achieved by the means of a three-way switch (5), the positions of which are: (i) switched-off state, (ii) e.g.
37 °C, and (iii) e.g. 43 °C. The equipment is fitted with a time-switch (6), too; thus, the moment of switching-on of the equipment or the switching over from a temperature value to an other one can be pre-adjusted.
The sample put into the pre-enrichment/enrichment medium is placed into the air capacity of the incubator and kept there overnight. Next morning, a transoculation onto isolating plates is carried out, then the plates are put again into the air capacity of the incubator adjusted to 43 °C. Next morning the plates are evaluated and, if necessary, the detection is continued in a known manner by transoculation onto an additional differentiating culture-medium. As it can be seen, the time demand of the detection of Salmonella has been significantly decreased by using the pre-enrichment/enrichment containing tetrathionate salt in combination with the culture-medium plates containing Brilliant Green and magnesium chloride. An additional advantage of this combination lies in that it can be used for detecting a cell count as low as 103/ml, whereas the usual methods give no reliable results below a cell count of 10s-106/ml. Furthermore, it has been found that an approximate estimation of the number of colonies can be made by carrying out the transoculation with a calibrated inoculating loop.
Obviously, the equipment according to the invention is useful not only for the detection of Salmonella but also for any other biological cultivations. The invention is illustrated by the following non-limiting Examples. When not stated otherwise, the chemical reagents used are products of analytical grade of the Merck Company.
Example 1
Preparation of a pre-enrichment medium A sterile, buffered peptone water was prepared by dissolving the following ingredients in 1000 ml of distilled water: casein peptone digested by trypsin 10.0 g sodium chloride 5.0 g
Na2HOP4.12H2O 9.0 g After sterilizing at 121 °C, the pH of the solution was adjusted to 7.0.
Simultaneously, sodium thiosulfate solution of 50 w/v% was prepared and sterilized at 121 °C.
Additionally, 20.0 g of iodine and 25.0 g of potassium iodide were dissolved in water and filled up to 100 ml.
100 ml of sodium thiosulfate solution and 20 ml of potassium iodide/iodine solution were added to 900 ml of buffered peptone water. The obtained buffered peptone water supplemented with sodium tetrathionate could be stored at +4 °C for one week. Example 2
Preparation of culture-medium plates containing magnesium chloride A base culture-medium was prepared from the following ingredients: meat extract 3.0 g casein peptone 5.0 g yeast extract 1.0 g
Na2HPO4.12H2O 0.5 g agar (purified, powder) 13.0 g distilled water 1000 ml
After sterilizing at 121 °C, the pH of the solution was adjusted to 7.6. A mixture solution was prepared from the following ingredients: Brilliant Green solution of 0.5 w/v% 6.0 ml
Neutral Red solution of 0.5 w/v% 6.0 ml sterile sugar solution of 10 w/v% 33.0 ml magnesium chloride 15.0 g sterile distilled water filled up to 100 ml
A previously sterile-filtered stock solution was prepared from magnesium chloride, from which the amount required was portionwise added to the mixture solution. The mixture solution was sterile-filtered through a bacterium filter.
Culture-medium plates were prepared by mixing 900 ml of base culture-medium solution heated to 50 °C with 100 ml of mixture solution similarly heated to 50 °C, the pH was adjusted to 7.0-7.2, then the solution was poured into Petri dishes to form plates. Example 3 Detection of Salmonella
After pouring 125 ml of pre-enrichment/enrichment solution prepared according to Example 1 to a sample of 25 g, the vessels were covered and incubated overnight in the incubator of the invention adjusted to 37 °C. Next morning, a transoculation was carried
out by attenuating spreading onto the isolating culture-medium prepared according to Example 2. The inoculated plates were incubated overnight in the incubator of the invention adjusted to 43 °C and the evaluation was carried out next morning.
Claims
1. Method for rapid detection of certain Salmonella species comprising pre- enrichment and/or enrichment, isolation and identification, wherein the improvement comprises using a buffered peptone solution supplemented with a tetrathionate salt as pre- enrichment or enrichment medium, respectively.
2. A method according to claim 1, which comprises using a culture-medium plate containing Brilliant Green and magnesium chloride for the isolation.
3. A process according to claim 2, which comprises using a culture-medium plate containing 0.02-0.05 g/litre, preferably 0.04 g/litre of Brilliant Green and 12-16 g/litre, preferably 14 g/litre of magnesium chloride.
4. Equipment for cultivation of microorganisms, comprising an air capacity (2) surrounded by a water jacket (1) and fitted with at least one temperature-sensing device (3), electric control device (4) for controlling the temperature as well as a three-way switch (5) and a time-switch (6).
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU29345/95A AU2934595A (en) | 1994-06-30 | 1995-06-30 | Method for rapid detection of certain salmonella species and equipment useful in the method |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
HUP9401958 | 1994-06-30 | ||
HU9401958A HU9401958D0 (en) | 1994-06-30 | 1994-06-30 | Process and apparatus for rapid propagation and isolation of salmonella species |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1996000794A1 true WO1996000794A1 (en) | 1996-01-11 |
Family
ID=10985394
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/HU1995/000031 WO1996000794A1 (en) | 1994-06-30 | 1995-06-30 | Method for rapid detection of certain salmonella species and equipment useful in the method |
Country Status (3)
Country | Link |
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AU (1) | AU2934595A (en) |
HU (1) | HU9401958D0 (en) |
WO (1) | WO1996000794A1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1999002649A1 (en) * | 1997-07-11 | 1999-01-21 | Oxoid Limited | Medium for recovery and growth of microorganisms |
FR2873714A1 (en) * | 2004-07-27 | 2006-02-03 | Rambach Alain | SELECTIVE ENRICHMENT MEDIUM OF SALMONELLA COMPRISING TETRATHIONATE AND MAGNESIUM SALT |
WO2007017601A1 (en) * | 2005-08-10 | 2007-02-15 | Institut Pasteur | Bacterial culture medium in a minimum inorganic medium, comprising gentisate and/or one of the precursors thereof, and use of 3-hydroxybenzoate in one such medium |
WO2010029360A1 (en) * | 2008-09-10 | 2010-03-18 | Solus Scientific Solutions Limited | Compositions and methods for the rapid growth and detection of microorganisms |
CN114350508A (en) * | 2022-03-17 | 2022-04-15 | 南方海洋科学与工程广东省实验室(广州) | High pressure environment marine microorganism enrichment culture and gravity separation device |
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HU194302B (en) * | 1985-05-29 | 1988-01-28 | Gyula Vamos | New plate culture medium and process for improved isolating salmonella species |
US4920063A (en) * | 1984-06-15 | 1990-04-24 | Biocontrol Systems, Inc. | Process for detection of selected motile organisms |
DE3904848A1 (en) * | 1989-02-17 | 1990-08-23 | Matthias Spanka | Cell culture device |
WO1994028163A1 (en) * | 1993-06-02 | 1994-12-08 | Foss Electric A/S | Method for the determination of salmonella |
-
1994
- 1994-06-30 HU HU9401958A patent/HU9401958D0/en unknown
-
1995
- 1995-06-30 AU AU29345/95A patent/AU2934595A/en not_active Abandoned
- 1995-06-30 WO PCT/HU1995/000031 patent/WO1996000794A1/en active Application Filing
Patent Citations (4)
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US4920063A (en) * | 1984-06-15 | 1990-04-24 | Biocontrol Systems, Inc. | Process for detection of selected motile organisms |
HU194302B (en) * | 1985-05-29 | 1988-01-28 | Gyula Vamos | New plate culture medium and process for improved isolating salmonella species |
DE3904848A1 (en) * | 1989-02-17 | 1990-08-23 | Matthias Spanka | Cell culture device |
WO1994028163A1 (en) * | 1993-06-02 | 1994-12-08 | Foss Electric A/S | Method for the determination of salmonella |
Non-Patent Citations (1)
Title |
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PATENT ABSTRACTS OF JAPAN, Section C, Vol. 18, No. 301, 1994; & JP,A,06 062 833 (NITSUSUI SEIYAKU K.K.), 08-03-94. * |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1999002649A1 (en) * | 1997-07-11 | 1999-01-21 | Oxoid Limited | Medium for recovery and growth of microorganisms |
WO1999002650A1 (en) * | 1997-07-11 | 1999-01-21 | Oxoid Limited | Selective enrichment and detection of microorganisms |
FR2873714A1 (en) * | 2004-07-27 | 2006-02-03 | Rambach Alain | SELECTIVE ENRICHMENT MEDIUM OF SALMONELLA COMPRISING TETRATHIONATE AND MAGNESIUM SALT |
WO2006021639A1 (en) * | 2004-07-27 | 2006-03-02 | Alain Rambach | Salmonella selective enrichment medium containing tetrathionate and magnesium salt |
US8728746B2 (en) | 2004-07-27 | 2014-05-20 | Alain Rambach | Salmonella selective enrichment medium containing tetrathionate and magnesium salt |
WO2007017601A1 (en) * | 2005-08-10 | 2007-02-15 | Institut Pasteur | Bacterial culture medium in a minimum inorganic medium, comprising gentisate and/or one of the precursors thereof, and use of 3-hydroxybenzoate in one such medium |
FR2889705A1 (en) * | 2005-08-10 | 2007-02-16 | Pasteur Institut | BACTERIAL CULTURE MEDIUM IN A MINIMUM INORGANIC ENVIRONMENT COMPRISING GENTISATE AND / OR ONE OF ITS PRECURSORS, AND USE OF 3-HYDROXYBENZOATE IN SUCH A MEDIUM |
WO2010029360A1 (en) * | 2008-09-10 | 2010-03-18 | Solus Scientific Solutions Limited | Compositions and methods for the rapid growth and detection of microorganisms |
CN114350508A (en) * | 2022-03-17 | 2022-04-15 | 南方海洋科学与工程广东省实验室(广州) | High pressure environment marine microorganism enrichment culture and gravity separation device |
Also Published As
Publication number | Publication date |
---|---|
AU2934595A (en) | 1996-01-25 |
HU9401958D0 (en) | 1994-10-28 |
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