Problems during media preparation
- Why do I get a different pH from the one stated on the product’s label?
There are a number of reasons that can influence the pH. One is "overheating".
Inadequate or unsuitable water may be another reason. Also, pH-determination may have been done incorrectly. Lastly, a contamination from the container itself may have contributed to the changing pH.
Overheating may be due to:
- Excess sterilization
- Heterogeneous mixing
- Repeated re-melting
- Improper storage
Ensure that the heating time and temperature are not exceeded and operate under ambient conditions.
Unsuitable Water. With regard to the water, the following should be considered:
- The purified water used should show a conductivity of less than 15 µS and a pH of between 5.5 and 7.7.
- When de-ionisers are being regenerated with acids and alkalis , residue of the HCl present in the purified water may cause the pH of the medium to lower
- Water, when not fresh, may have absorbed CO2 from the atmosphere.
The composition of culture media is adjusted to provide the correct pH after reconstitution and sterilization. Should the medium be supplemented, the pH limits apply to the complete medium. Any adjustment of pH should not be done prior to autoclaving.
Obtaining a different pH reading may be due to:
- pH measurement performed outside the temperature specifications (10°-37°C). In such instances, allow the medium to cool, and re-check within the temperature sopecifications.
- Incorrect electrode used
- Agar products, at ambient temperature, will be in solid form and require the use of a flatbottomed pH probe, in order to facilitate measurement. The use of temperature compensation is not recommended. We suggest a combined electrode with the following specifications:
- pH range : 2.0 to 11.0
- Working temperature range : 0.0 to 80°C
- Reference electrolyte : polymerized and without AgCl
- Diaphragm : open
- Expected life : 4 to 6 months, depending on the use.
- Broths are liquid and we recommend pH probes that are resistant to proteins and provide fast readings, such as those with a triple ceramic diaphragm and a wider sensitive membrane surface area having the following specifications:
- pH range : 0.1 to 12.0
- Working temperature range : 0.0 to 100°C
- Reference system : crystals of Ag / AgCl encapsulated, CRISOLYT-G electrolyte
- Diaphragm : 3 types of ceramics
- Expected life : 1 year or more when used correctly.
- The Electrode used is not properly calibrated. Re-calibrate the pH meter with Scharlau pH buffer solutions
- Temperature compensation: We do not recommend the use of temperature compensation.
Make sure that the glassware is of a suitable quality for the preparation of culture media and avoid using soda glass. Rinse glassware before use, to achieve neutrality.
- Is there any protocol or method that is recommended to re-melt agars in flasks using the microwave?
There is nothing stipulated by any directive, however Scharlab usually recommend the following steps whenever bottles having the correct metal cap are used. Note that while metallic components cannot be placed in a microwave, Scharlab has developed an exclusive metallic cap that enables the re-melting step to be carried out in a microwave. This process improves the time spent in analytical laboratories. The following procedure is recommended:
- Place the flask in a beaker with water to ensure uniform temperature distribution.
- Place inside the microwave.
- Following the application of heat observe and gently stir to facilitate complete dissolution of the agar.
- If the agar is not completed melted put the beaker containing the flask in the microwave again, until a homogeneus appearance is observed.
- Pour the agar plates using the standard technique.
- Which microbes will grow in which media?
Check the Certificate of Analysis (COA) proivided for each batch of media. These details can be found in our website, under ‘Support Menu’, ‘Technical Information’. From this information you will see the control strains that have been used to carry out the performance tests. A picture of the growth of several test strains will also be found on the CoA.
- What are the possible causes for a loss of growth?
- Repeated melting-overheating.
- Inadequate or improper mixing.
- The inoculum itself: the addition of inhibitors or excessive electrolytes during inoculation.
Please also check the expiry date on the bottle and the general appearance of the medium in dry form. Humidity may degrade peptones contained in the formula. Contact with air may have oxidized any of the supplements. Exposure to sunlight may have altered the colour of the medium. Ensure that each bottle is properly closed after each use and stored in a dry place away from direct sunlight.
Plates are products which are very sensitive to sudden changes in temperature. Once outside our facilities, it is complicated to be able to control all the factors that can lead to product alterations. These products are manufactured in non-sterile, ISO 7 clean rooms. Scharlab has optimized its processes and has managed to work with an AQL <0.5%.
All our shipments of culture media prepared within Spain are made in trucks that record the low temperature to which the transported product is subjected. This record of temperatures can be consulted through the link provided in the automatic mail of departure notice of the merchandise. If you have a problem with the product, this document can be useful to investigate the cause.
In general, upon receipt of these products at your facilities, we recommend following the storage instructions indicated in the same box or in the technical documentation of the product. In case the storage conditions are in a refrigerator or cold room (2-14ºC), it is important to remember that the product must not touch the walls of the equipment, to avoid freezing.
Regulations & Directives
- What is a "Certificate of Suitability"?
The Certificate of Suitability assures the buyer that BSE is absent.
The Certificate of Suitability is granted by the Committee of European Directorate for the Quality of Medicines (EQDM) of the European Pharmacopoeia.
It is granted to manufacturers of raw materials only and given for every single raw material. It is not given to the Company.
For this reason, the company using the raw material has to be ISO 9000 or GMP certified.
Every time that any raw material or process is changed, or if the validity period has expired, the manufacturer has to re-apply for a renewal.
BSE should be of no concern, given that culture media is not ingested. However, in the pharmaceutical industry, sterility validation of the filling machines have to be carried out periodically. This is done by passing broth media through the filling machinery (aseptic media fill experiments). Thus, if these media were contaminated with BSE, it could then be transmitted to humans or animals through the medicines that are produced using these filling machines..
- Are Scharlau media free from BSE/TSE?
We buy our raw materials of animal origin from those European manufacturers that can furnish us with their "Certificate of Suitability", which guarantees the absence of BSE/TSE infection. A "BSE free certificate" can be downloaded from our webpage. ( Please refer to our FAQ "What is BSE? and What is a "Certificate of Suitability"? )
- What is the BSE disease?
BSE is the abbreviation for the disease called Bovine Spongiform Encephalitis, also called Transmissible Spongiform Encephalitis or Mad Cow Disease and is mainly contracted by cattle.
In sporadic cases sheep have also been infected.
Originating in the U.K. BSE then spread to several other European countries.
This disease is not found in Australia, New Zealand or the USA.
The prions causing this disease can infect the culture media through the use of raw materials of bovine origin, such as meat peptones, meat extracts, proteose peptone, bile and bile extracts, etc.
Note that casein peptone is made from milk and milk is devoid of BSE prions. In order to convert milk into casein, an enzyme is required which is of non-bovine origin. Hence BSE free certification is not required for casein peptone.
Due to the serious threat that BSE poses, media manufacturers in Europe have started using raw materials of bovine origin from Australia, New Zealand and the USA.
- What risks am I exposed to when working with culture media?
The majority of culture media are harmless. Only some media, that contain selective agents like sodium azide or bi-selenite, can be regarded as somewhat toxic and a safety mask is required when working with such agents.
The main threat may come from the manipulation of pathogenic micro-organisms. Protect yourself by working under laminar air flow cabinets and use glasses, masks and gloves.
- How can I get an SDS of prepared culture media (plates, bottles, tubes etc.) Are SDS required for such media?
Prepared culture media is considered to be "non-toxic" according to Article 31 of Regulation (EC) 1907/2006 (REACH). Because these products are manufactured using high dilutions of their respective dehydrated culture media, the regulators consider them as containing no hazardous ingredients or substances requiring Community workplace exposure limits and that the such media do not contain substances of very high concern (SVHC) or are above the stated limits. Therefore a safety data sheet for these types of products is not necessary . For these reasons, no documentation for such products is available.
- Is there any document showing the directive of all our culture media?
Scharlab SL manufacture under the ISO 9001 directive, that regulates all our manufacturing and quality processes. Included in our microbiology catalogue is an informative table containing all international and locally recognized Organizations and Directives. All media described in the catalogue includes the relevant abreviations of these Organizations or Directives. Moreover, all our technical data sheets include details according to any special directive (Harmonized Pharmacopeia, ISO, BAM…) that may be applicable to any of the media listed.
Culture Media Products
- Why do we have different MacConkey Agar and what is the difference between them?
MacConkey Agar is a culture media, either in agar or broth form, that can be used to detect different kinds of pathogenic microorganisms (mainly gram negative bacteria) in clinical samples, by modifying the type of one component, namely, the Bile Salts. We can find different references and types of MacConkey agar in the Scharlau portfolio:
Ref 01-118: MacConkey Agar or MacConkey Agar nº3
This is a selective and differential media used in the detection, isolation and enumeration of Salmonella and coliforms in clinical specimens according to Pharmacopoeial Harmonized Methodology and foodstuffs according to ISO 21150:2006. It is also known as MacConkey Agar nº3 since it includes Bile Salts type 3, which strongly inhibits the growth of gram positive bacteria.
Ref 01-682: MacConkey Agar nº2
This media is a modification of MacConkey Agar containing bile salts nº2 for the identification of enterococci (gram positive bacteria). Bile Salts nº2 are less inhibitory than nº3 thus enabling enterococci to grow. Such Enterococci present as a pale color among coliforms and Salmonella and their presence indicates faecal pollution in the tested sample.
Ref 02-118: MacConkey Broth
This is a liquid medium used for the detection and enumeration of coliforms by MPN technique. While it is as a popular enrichment media for coliform bacteria, it does not comply with Pharmacopoeia formula.
Ref 02-611: MacConkey Broth (also Medium 6)
A liquid medium, for the detection and enumeration of coliforms, according to the Pharmacopoeia Harmonised Method due to the addition of Bromocresol purple in its formulation, that is a less aggressive indicator than Neutral Red referred to in the previous reference 02-118.
Ref 01-729: MacConkey Sorbitol Agar (SMAC Agar)
Selective and differential solid medium for the detection of Enterohaemorrhagic Escherichia coli (EHEC O157:H7) according to ISO 16654:2001. In this formulation, lactose is substituted by sorbitol which allows the identification of enteropathogenic E. coli serotypes O111 and O55. When the media is supplemented with cefixime and potassium tellurite (06-146LYO1) it becomes CT-SMAC Agar; a very excellent media to detect E.coli serotype O157:H7
- What is the advantage between our ready-to-use broths in Flexibags and the Dry Bags offered by Oxoid and any other brand?
Dry bags consist of plastic bags containing irradiated dehydrated media (Buffer Peptone Water, TSB, or Half Fraser Broth) containing a pre-weighed amount of media sufficient to prepare 20L. From a distributor’s viewpoint these broths provide a very good option to enable transport costs from the point of manufacture to the customer to be decreased . However, once the product arrives at the customer’s laboratory they will need to have available a sterile water pump, which is always perfectly controlled and they will need to certify that the final 20L bag will perform according to specifications.
While dry-bag broths may provide a logistic advantage, preparation of the end product at the customer’s site can be time consuming and expensive.
In order to mitigate such problems, Scharlau offer their Flexibags - ready-to-use steriled broths in bags of 2L, 3L and 5L - prepared ready to use on arrival at the customer’s laboratory. Included with our Flexibags are the Certificates of Analysis detailing the expected biochemical and microbiological results.
- Why do we have different Blood Agars and what is the difference between them?
Media containing blood becomes a very rich base for the isolation of pathogenic microorganisms from clinical specimens. Because there are many different genera and families of pathogens, there are some bases that are better than others for the isolation and identification of pathogens.. All Blood Agars from Scharlau are bases that should be supplemented with the corresponding blood (e.g. sheep, horse, defibrinated blood). Scharlau present the following Blood Agars in their product portfolio:
Ref 01-352: Blood Agar
A nutrient rich medium suitable for the isolation of pathogenic microorganisms from clinical specimens. A mínimum of 5% of defibrinated blood should be added as the supplement. The addition of blood makes this product suitable for the study of haemolytic activity.
Ref 01-034: Blood Agar Columbia (CA, Columbia Blood Agar)
Nutrient rich medium suitable for the isolation of pathogenic microorganisms from clinical specimens. A mínimum of 5% defibrinated blood should also be added in order prepare what we refer to as Blood Agar. Due to this product containing casein and meat peptone, it is suitable for use in the preparation of selective media for diagnostic applications. The alternatives are:
- Agar without either enrichment or inhibitors: supports growth of normal microorganisms such as enterobacteria and the more fastidious organisms
- Clostridium Selective Agar base: add 240mg/L sodium Azide and 180mg/L neomycin. Without blood
- Blood Agar: add 5% sterile defibrinated horse/sheep blood. For the determination of typical haemolytic reactions of enterococci, streptococci, staphylococci and other microorganisms.
- Selective Gram positive cocci Blood Agar: 5% of defibrinated blood + 10mg/L of colistin + 15mg/L of nalidixic acid. An excellent selective media for gram positive cocci.
Ref 01-689: Blood Agar Base Modified:
This media is a modification of previous formulations of Blood Agar, Blood Agar Columbia and Blood Agar nº2. and has been manufactured in response to a suggestion from one of our customers. It is used in the detection of haemolytic activity of pathogenic bacteria.
Ref 01-505: Blood Agar nº2
Nutrient rich medium suitable for the isolation of pathogenic microorganisms from clinical specimens. The blood agar nº2 allows maximum recovery of weak organisms without altering or interfering with their haemolytic reactions. Although this media has an equal or higher stimulatory growth capacity than the other blood agar bases, it is specially formulated to promote pigment production in chromogenic bacteria.
Ref 01-703: Blood CNA Agar (Columbia CNA Agar)
Solid medium used, with the addition of blood, for the selective isolation of Gram-positive cocci, from clinical samples. Defibrinated blood should be added in a proportion of 5%. Its formula contains colistin and nalidixic acid that inhibits the growth of gram negative bacteria and allows the media to be selective in the detection of gram positive cocci and fungi in urine samples.
- Can Clostridia sporogenes grow in m-CP Agar?
m-CP Agar (01-513 + 06-125LYO1) is a solid medium for the enumeration and isolation of Clostridium perfringens in water according to the European Directive 12767/97. Although the main microorganism to detect is C.perfringens, there are some analytical laboratories that detects other Clostridia species, as for example C.sporogenes. Although this microorganism is not indicated in our Technical Data Sheet of dehydrated media, this microorganism is analyzed in the prepared media presentation (filtration plates 064-PF0030) giving a good performance. We can therefore guarantee that C.sporogenes grows in m-CP Agar dehydrated medium (01-513 + 06-125LYO1) as this is used as raw material for our prepared medium.
- 5. Which are the medias indicated for the detection and identification of Shigella?
ISO 21567 describes the methods to detect and identify Shigella spp. These methods are very extensive since Shigella is classified within the Enterobacteria group and is very similar to E.coli, one of the most indicative microorganisms of biological contamination.
ISO 21567 recommends as the first step, the selective pre-enrichment in Shigella Broth, reference 02-662. Following this step, the sample should be inoculated in 3 selective medias: 01-118 MacConkey Agar, 01-216 Hektoen Agar and 01-552 XLD Agar.
Following incubation of the media the results should be confirmed by a serial of biochemical tests:
- Isolation in 01-140 Nutrient Agar
- Tests in 01-192 TSI Agar, 01-261 + 06-083-100 Urea Agar and 01-665 Acetate Differential Agar which is the media that will allow the differentiation between Shigella and E.coli. There is also Christensen’s Citrate Agar, ref 01-664, which allows the detection of Shigella and the inhibition of Salmonella growth due to the presence of E. Coli.
- Unfortunatelly there is no chromogenic media for Shigella yet, and Scharlab does not have a line of rapid test kits such as latex tests or biochemical galleries.
- When we say that our Irradiated prepared culture receives between 8 and 14KG, on which level of SAL (Sterilization Assurance Level) is this based?
The Sterilization Assurance Level (SAL) is a rate used to analyze the percentage of sterility obtained after an irradiation process. It is indicated as a scale of 1-5.
In our processes, we don’t use this scale to indicate our irradiation effect over the plates, however we report the effectiveness of the radiation as percentages.
Our irradiation process of plates, assures a sterility of 99,9%. Because plates are irradiated in different external packaging, once the process concludes, each plate is visually examined at the final packing stage. Proof of the integrity of our irradiation process can be seen in our long experience in successfully selling these plates in our markets.
- Could we find slight differences in pH in the COA compared to TDS and l? For example, King A, ref 01-001, batch 102304 indicates pH=7.37 and in the COA a pH 7.37 which is different from the TDS and label both of which indicate a pH 7.2. Why is this happening?
The limits of pH in the TDS and label are 7.2 +/- 0.2, so the result in the COA is correct at pH7.37.
Normally TDS and labels contain a range of pH since there can always be a slight yet insignificant variation between batches. These pH ranges are stipulated by the same ISO or directives relevant to these media.
- Could a customer use CCA Agar (01-695) when using the pour plate technique?
CCA is not a recommended media for use in the pour plate method. The pour plate method provides for a stratified growth of all possible microorganisms. Because CCA is a chromogenic media with the colonies being differentiated by color, were they to grow in a stratified form along the plate, the customer wouldn’t detect the colors correctly and this would lead to confusion.
The best method using CCA is by membrane filtration Should the customer prefer not to use this method, or it not be available to them, they could spread the sample over the plate as in normal spreading, using a Drigalski loop.
- Why for certain of our media products, do we sometimes have different weights in grams per litre compared to other brands?
Every formulated media contains certain quantity of ingredients in order to provide selection, specification or inhibition characteristics to detect and identify microorganisms. Agar is the component that solidifies the media, allowing the permeability of all other components. Agar selection should be done very carefully for each media. The quantity of agar contained in each media will depend on its formulation.. Every brand purchases their agar from different sources with each soruce having different strengths. In some cases, Scharlau media contains slightly more grams of agar in the formula and therefore, the weight of media to prepare 1L can differ slightly compared to other brands.
- Why do we have a specific media for Legionella BCYE without L-cysteine?
L-cysteine is a necessary amino acid for Legionella growth. The analysis of Legionella is initially performed in GVPC Agar (01-687 + 06-137LYO1 + 06-138LYO1) followed by suspicious colonies being inoculated in BCYE Agar (01-687 + 06-137LYO1).
Since other bacteria can also grow in BCYE media, the incubation of the suspicious colony in BCYE without L-cysteine (01-687 + 06-134LYO1) will inhibit Legionella, whose growth requires L-cysteine, and the user will be able to compare the results with results in BCYE Agar.
Therefore BCYE without L-cisteine is used to compare results with BCYE Agar, confirming that colonies growing in BCYE Agar are inhibited in BCYE without L-cisteine.
- What does TLHTh means?
TLHTh are the letters Tween + Lecitin + Histidine + Sodium Thiosulfate these being growth factors (Lecitin, Histidine) and neutralizing agents (Tween, Sodium Thiosulfate) in culture media. The product is used in the analysis of surfaces that have been cleaned with desinfectants or quaternary detergents It is also used to neutralize conservative products in the cosmetic industry.
- What is ß-Lactamase and Penase?
ß-Lactamase is a family of enzymes produced by certain bacteria providing the bacteria with resistence to ß-lactamic antibiotics such as : penicilins, carbapenems, cephalosporines and bactems.
ß-lactamases breaks the ß-lactamic ring contained in all these antibiotics these antibiotics allowing the bacteria to grow and expand without inhibition. The presence of ß-lactamase resistent bacteria is the main problem in clinical centers and the worst headache for pharmaceutical companies.
Within the ß-lactamase group there is Penase, also known as Penicilinase, which is the specific enzyme that metabolizes the penicilin antibiotic.
In microbiology, Penase and ß-lactamase are used in culture media to inhibit the effect of antibiotics and control the growth of any bacteria, which may can be masked by the effect of the antibiotic.
- In our Urea Agar & Broth, (our catalogue reference 01-261 and 02-261), Scharlab don’t include the urea component in the same formula since this should be added after the media is reconstituted. This step denotes the difference between brands with some including urea in the formula while others recommend adding urea after reconstitution.
There are differences in the formulation of Urea Agar and Broth among the different brands in the market. Like Scharlab, there are brands that do not include the urea component in the formula, recommending it to be added in sterile solution once the base media has been reconstituted and autoclaved. When the Urea component is not included in the formula, the Urea Agar Base includes the Agar component and the base media can be autoclaved for sterilization. Customer should add the sterile Urea solution after media autoclaving at a final concentration of 20g Urea/L.
On the other hand, brands that include the 20g/L of urea in the formula, only offer Urea Broth which should be heated and filtered and not autoclaved after reconstitution. Should the customer need to prepare the Urea Agar, which is the most common media, the agar component, once sterilized, should be added and mixed into the broth.
Thus there is no a significant advantage in adding the 20g of urea component in the formula of the media since if it is included, the media cannot be sterilized by autoclaving and the agar should be added separately requiring an additional purchase.
- What is the meaning of the sentence of "The media must be reduced before use" as detailed in the preparation instructions for the Scharlau Iron Sulfite Modified Agar, reference 01-634?
Reducing the media releases the trapped oxygen that the media can absorb should it not be used on the same day of preparation. In order to release the oxygen, prepared tubes can be regenerated by placing them in a heating bath for a few minutes. In our handbook page 23 ,there is a brief explanation about Medias for Anaerobes and how to work with them.
However, it is also known that if a customer prepares tubes, seals them well and stores them in an anaerobic jar, there is minimal risk of the media becoming oxygenated and reducing it will be therefore be unnecessary.
- What is the best way to re-melt solidified agar? How many times can the agar be re-melted without affecting its efficiency?
We recommend that the best method to re-melt solidified agar is to use a water heating bath with a controlled temperature so as to avoid overheating the agar and lthus losing its properties.
In order to maintain the efficiency of the agar, it is not recommended that it not be re-melted more than once.
Re-melt solidified agar in a microwave or should a customer prefer, use a suitably validated steam autoclave .
- How long can we store unused,prepared broths and agars in the fridge once reconstituted?
For general media, broth and agars can be kept from 4 to 6 weeks at 2-8ºC should the customer not use them on the day of preparation. It is recommended to seal the plates individually and place them upside down.
Some selective media should not be stored for longer than 3 weeks at 2-8ºC
- Should the pH of the media be checked before and after preparation? If so – how?
It is not always necessary, but we recommend that the pH of the media be checked both before and after autoclaving; for medias with a final pH below 6, this is always necessary.
Use a normal electrode. To check the pH
After autoclaving media, the pH should be checked just before it solidifies and once in the plate the pH should again be checked by stabbing the plate with the electrode.
Should the pH require modification, this should be done using a weak acid or alkali.
- Where a supplement cannot be used on the day of preparation, can it be stored for future use?
It is not recommended to keep reconstituted supplements for longer than the day of preparation. There is no directive recommending any protocol for this, nor is Scharlab validating such a process in their QC Laboratory.
However, should the customer wish to store the remaining supplement in the fridge or in single doses in the freezer, they could validate the process themselves.
- Could we offer our supplements to customers using another base brand?
Yes, whenever the base media has the same formula as ours (according to the ISO formula), we can offer our supplements as alternatives.
However, it is our aim to offer the full pack (base + supplements) to all our potential customers.
- When promoting our Microinstant Chromogenic Listeria Agar (ref 01-719) what arguments do we have when discussing these products with those customers using culture media validated by AFNOR or AOAC?
Our Microinstant Chromogenic media is based on the same formula as described in ISO 11290. This means that it is totally valid to follow ISO standards. Therefore, there is no real necessity that it also be validated by such recognized international institutions in order to sell our media.
However, customers who have accrediation with these AFNOR or AOAC validated medias may be reluctant to change the brand since in some cases they will have to revalidate the products which becomes an ardous task for them. For these customers, we are able to prepare a complete offer including other products used in Listeria detection so that they can get an economical benefit in the end, and the advantage of having two validated brands in case they run out of stock.
- What is MPN?
MPN is the abbreviation of a technique called Most Probable Number.
This is one of the most employed methods for determining the probable number of viable bacteria in a given sample.
It is a statistical concept derived from the Probability Theory.
The most important points to be considered before carrying out the MPN are as follows :
- The micro-organisms need to be distributed homogeneously in the sample. If not, then a proper homogenization of the sample should be performed.
- An adequate and suitable cultivation medium should be used for each type of micro-organism, so that even if there is only one single cell, growth can be detected. The MPN method gives less accurate results if there are cell associations or masses.
- In the actual methodology, a series of dilutions of the sample to be analysed is prepared in such a way, that the growth can be observed in tubes with the lowest dilution and no growth in the higher dilution. Readings are performed after the required incubation period.
The appropriate number of viable organisms in the original sample is calculated according to the probability table: "McCrady's Table" ,that can be found in the Scharlau Handbook
- What is the best method of inoculating agars and when is each method used?
Several methods exist to inoculate a sample on a plate:
- Streak plate method, for the isolation of bacteria.
- Spread plate method using a Drigalsky loop.
- Pour plate method, for mass inoculation.
- Stab method, to analyze anaerobic activity of some microorganisms.
The decision regarding which method to use depends on the type of media and the microorganism that is being analyzed.
Additionally, ISO or other references may provide direction regarding which method to use.
- Do we have HC Agar for Candida albicans?
Yes, we did have this product however it was discontinued due to the small consumption among cosmetic laboratories. Now, due to the increase in industry demand, , we again have this product under our reference No. 01-298-500, HC Agar, available via our website (TDS, SDS).
- Some customers, having completed all the steps associated with pathogen detection, usually use galleries such as API for identification of the pathogens. Do you have such galleries available?
ISO recommends the identification of pressumptive pathogens by traditional tests using identification culture media. However also mentioned in the recommendations are the use of alternative methods of identification such as serological and immunological tests, including APIs or latex tests.
Scharlab is manufacturing a variety of traditional media for detection and identification. Unfortunately technology demands mean that we don’t currently produce identification galleries but we can market API galleries.
- What type of neutralizing agent should the customer use to test the final product?
The type of neutralizing agent (e.g. Tween 20, Tween 80, Lecithin, Histidine,) will depend on the type of final product to be analized. ISO 21148 describes the neutralizers and the concentrations to be used depending on the preservative of the sample. Different final products may be neutralized with different neutralizers.
- Are there any issues associated with the customer makeing two enrichments using the same diluent however using the first enrichment without neutralizer and the second with neutralizer?
There is no any problem in performing two steps of enrichment using the same base media,; the first without neutralizer and the second with neutralizer. However such a procedure is not according to ISO. recommendations.
We perform the complete process in one single enrichment step that includes the neutralizer. In so doing, the sample is both enriched and neutralized, as recommended by ISO.
One extra enrichment step will only delay the quality control protocol and consequently, the final product release.
- Which type of membrane should be used to filter the sample?
ISO 21148 describes the materials that should be used to do quality control. In general, the common membrane used in this case is the pore cellulose membrane 45μm and 47mm in diameter. For oily matrices it might be necessary to use a more specific membrane that would allow the filtration of the product, ou will find this also explained in the ISO.
- Is there any problem should a customer perform the Growth Promotion test with ATCC strain other than the one described by the ISO?
Laboratories may validate their culture media with the ATCC strains that are indicated in the ISOs. However, they will have to prove the validity of the test at any audit.
A different ATCC strain than that recommended by ISO may also gro won the media. However in some cases, some ATCC strains are difficult to recover. As such, the customer may face problems when using such strains. We strongly recommend that ISO procedures are followed. Therefore we fully support using ISO protocols.
- Could Scharlau supply the ATCC Strains?
Scharlab offers a wide range of ATCC strains through the trademark Scharlau MiStraCon. This product line can be supplied worldwide, although the mode of transport must be defined for each case. In addition, Scharlab can also commercialize Microbiologics strains in the Spanish state.
TDS, SDS & Labels
- What is the meaning of the number that appears before the batch number in supplements, additives and prepared culture media?
The number in front of batch number on our labels denotes the serial number of the vial bottle or plate and refers to the position of the vial, bottle or plate within production run.
This information is very useful should there be a problem during production, during control analysis or once the product is release to the market . Using this number we can track when any unexpected problem occured.
- Do you include TDS (Technical Data Sheets) and COA (Certificate of Analysis) in the boxes containing the bottles?
Previously, we included this technical information inside the boxes of our products. However all these documents can now be freely downloaded from our webpage and as many copies as necessary can be printed. It was therefore decided to no longer include them in our packaging material. Experience has also shown us that these documents were often missing when the product was received by the customer.
- How often are SDS updated?
Because SDS contain information about safety issues such as:
- Dangerous goods classification
- Dangerous pyctograms
- Transport conditions
- Storage conditions
They are regulated by Directives pertaining to such information. As such any change to these directives will require an updated SDS.
We have already updated all their SDS to REACH requirements and currently,there are no other new regulations that necessitate a review of our existing SDS information.
Our Quality Assurance Department monitors any modifications required to ensure that our SDS’s are up to date.
- Do the Scharlau culture media follow the ISO 11133: 2017 standard?
All Scharlau culture media intended for industry are manufactured and controlled in accordance with the requirements of ISO 11133: 2017 "Preparation, production, preservation and performance testing of culture media".