Using various selective and diagnostic media is standard practice. The selective media often have specific carbon sources, inhibitors and stains to allow for visual discrimination of bacterial species. The number of media types depends on what bacteria you expect in your water supply. TSA and R2A media have differing sensitivities for detecting certain types of bacteria although for most pathogens R2A is more sensitive but it has a longer incubation time. MCA is gram negative selective and visualized lactose utilization. MSA is for Staphylococcus species with discrimination for coagulase activity. With CA do you mean Columbia Blood or Centrimide? Columbia blood agar is to identify haemolytic bacteria.

Technically you could use qPCR to identify bacteria species/strains but agar plates are probably cheaper.

Some use PCA (Plate Count Agar) , I prefer R2A. Selective media are not used typically for initial testing - if you're system is that contaminated, you're screwed.

ID is by the same protocols used for finished product isolates - usually some rapid method as classic plate/tube micro takes too long. You should be working with an alert/action based "spec".

Here's USP on purified waters - http://www.uspbpep.com/usp29/v29240/usp29nf24s0_c1231.ht ml

I also suggest you subscribe to PMF (Pharmaceutical Manufacturers Forum ) Listserve at http://www.microbiologynetwork.com/pmflist.asp

Hello!

I recommend using Endo agar to grow on membrane filters the Enterobacteriacea colonies on its surface. The colonies of most of them will differ from each other in cultural characteristics.

"BD Endo Agar is a slightly selective and differential medium for the isolation and differentiation of Enterobacteriaceae and several other Gram negative rods from clinical specimens".

In the microbiological analysis of purified water, the choice of media depends on the specific microorganisms you want to detect and quantify. Experienced microbiologists typically use a combination of selective and differential media to isolate and identify various types of microorganisms commonly found in water samples. Here are some commonly used media:

Kais Khudhair al Hadrawi

I disagree with your response and can only assume you've never worked with pharma purified water systems. It is absurd to seek Vibrio cholerae in a purified water system or use multiple media targeting enteric bacteria. Please recall the question addressed purified water in a pharm context - not surface or drinking water.

Pharmacopeial practices are well established and these indicate the media.

http://ftp.uspbpep.com/v29240/usp29nf24s0_c1231.html#usp29nf24s0_c1231

Article Classic and alternative disinfection practices for preventin...

You may look into the article here. Hope it helps

As a microbiology Quality control official in a variety of facilities including clinical laboratory, pharmaceutical manufacturing pilot plant, wastewater treatment laboratory, I have followed the traditional methods to analyze samples. I first started with plate count agar, EMB agar and Sabouraud Dextrose agar, Sabouraud dextrose agar with chloramphenicol agar for initial screening to look for pathogens including yeasts and molds. I would plate in triplicates and at growth temperatures of 10°C, 25°C, 37°C, and 42°C. If there is any growth, I would then streak different colonies on specific differentiating media and utilize the ones that have been listed by previous scientists.

Kailash CHANDRA Srivastava

Wow did you waste media, time and money in testing pharma water. Such testing is excessive and certainly does not provide the timely results so critical in responding to purified water system contamination and biofilm development.

No Pharmacopoeia would ask for the complexity.

you can use member filter technique and PCA for total count and coliform could also be counted by using selective media.

With all due respect to Phil Geis, I beg to disagree with appreciation, the connotation mentioned in your comments.

WHEN PATIENT HEALTH IS OF PRIME IMPORTANCE, a few mLs of sample and culture media used is not considered a waste in the overall context, especially when considering the size of pharma industry.

I have practiced microbiological QA/QC in a variety of industries over a period of almost little over 45 years. During this time the field has evolved tremendously. 50 years ago, one would require a minimum of 5 mL of sample, general requirement was 10 mL in case a re-confirmation was required. Then, the sample size reduced, and now a days, I read that one requires only a few microliters of both, the sample and the culture media. With new PCR and rRNA techniques one can get the answer in orders of magnitude less time than the standard which at the time was of 24-48 hours for bacteria and up to a week for fungi and yeasts. Furthermore, if psychrophiles were expected, standard requirement used to be incubation time of 14 days. I would also cite that not very long ago, in a clinical laboratory a blood culture sample was incubated for up to 10 days and multiple sub-samples were tested to ensure a pathogen is not missed. A few weeks ago, I encontered a similar situation in a Hospital setting, the results of blood culture were obtained within 2 hours- because of r-RNA technique. I was told, none-the-less, the blood sample would still be maintained and monitored for 10 days.

To put the science in perspective on a global scale, there are many parts of world, where even today, the so called "rapid and modern techniques" are not afforded by many facilities for economic, or non-economic reasons. When I opinioned about the microbiological technique, it was addressing the problem with all types of facilities in mind.

Additionally, if one reads the 24th edition of "Standard Methods for the Examination of Water and Wastewater", a world-recognized compendium on examination of water quality, published in 2023; one would see some of the methods that I have mentioned. For the record, I humbly mention that I am one of the "methods editors" on the Committee that writes and modifies those methods every two years. I have been doing this work of methods editing since 1995.

Kailash CHANDRA Srivastava

This has nothing to do with posturing a few ml's for "patient health" - this is a question of water testing for product quality. The subject of Mr. Diriarin's original post is water quality in cosmetic production for which you apparently have no experience. I do have this knowledge and extensive experience (40 years in industry) in this matter

https://www.routledge.com/Cosmetic-Microbiology-A-Practical-Approach/Geis/p/book/9781138732919

and teach this subject in a graduate level course at a major university's dpt College of Pharmacy.

Please understand, one cannot test quality into a material by running every micro test one can imagine. That merely wastes money, energy and time. Mr. Dirianin's water system is validated (standard practice) and such systems will have very low levels of microbial presence - that's why filtration is used. Selective media do not increase recovery - they facilitate detection/id. There is not/should not be numbers of microbes recovered be a background of growth from which one that demands selective media. Managed by an alerts/action protocol, the primary medium is nonselective. as you care about counts and presence of biofilm forming bacteria (esp. Gram negatives and pseudomonads in particular) and must respond immediately per protocol to any growth.

Pharmaceutical production is similar . If you have experience in this context you would be familiar with Pharmacopoeia that guide if not dictate production and testing protocols. US Pharmacopoeia specifies R2A.

http://www.uspbpep.com/usp29/v29240/usp29nf24s0_c1231.ht ml

Industry practices vary a bit - some use PCA and others USP QC chapters. whether R2A, PCA or USP 61/62 - one will obtain growth of all the microbes your media collection would seek.

No idea why you offer Standard Methods reference. It's irrelevant to cosmetic/pharma water systems and in no way does potable water testing involve your media blitz.

I would prefer the use of nutrients agar medium

Chidi Nduka Amadi-Ikpa

Sure.

Some folks think recovery from a nutrient poor source (purified water) is better with low nutrient media (e.g. R2AArticle A New Medium for the Enumeration and Subculture of Bacteria ...

Description and references that Phil Geis cited are well taken.

I am extremely familiar with U.S. Pharmacopeia, a compendium and guide that has been known to exist since 1820, not only U.S., but also British and European. I have regularly consulted these publications while preparing /updating my lectures for the graduate and undergraduate students over my career spanning almost 48 years and since 1995, while editing the methods developed/updated in the “Standard Methods for the Examination of Water and Wastewater”. In fact, Phil Geis mentioned about the potable water testing for which the methods described in the "Standard Methods for the Examination of Water and Wastewater are supposedly the "Gold Standards". I am certain that everyone working with the quality of water is cognizant of this publication. This is published under the joint sponsorship effort from the American Public Health Association, The American Water Works Association and Water Environment Federation.

I further appreciate the comments from Phil Geis to enlighten my understanding of the methods for water quality examination for the pharmaceutical and cosmetic industry. As I mentioned in my comments from yesterday, while being cognizant with those methods, yesterday, I have merely commented more from a global perspective; rather than from the so called, “developed world” perspective. Every practitioner has different choices. Just like Amadi –Ikpa uses nutrient agar. Also, as we all know, sometimes the samples are enriched to check for the existence, or complete elimination of specific bacteria, e.g., Escherichia coli, that might have been damaged or injured during water purification process and might require additional nutrients, or longer time to grow. Thank you!

I recommend Mueller-Hinton agar medium