Archive for the ‘MWF Microbiology’ Category


DORMANT MICROBES IN METALWORKING AND OTHER INDUSTRIAL FLUIDS


John Cleese and Michael Palin of Monty Python’s Flying Circus in the “Dead Parrot Sketch”, first aired in December 1969.
What is a dead microbe and why might we care?

I today’s post, I’m returning to a topic I first discussed in 2019 (https://biodeterioration-control.com/2019/07/). In the Monty Python’s Flying Circus “Dead Parrot Sketch”, John Cleese plays the role of an unhappy customer who believes that he has just purchased a dead parrot. Michael Palin – playing the shopkeeper – insists that the parrot is not dead. Rather, it is “simply napping.”

When we monitor microbial contamination in industrial systems, we are typically interested in both how much microbial contamination is present and what damage risk the population poses to the system and the fluids it contains.

Last week, I received an email from a metalworking fluid (MWF) manager who wrote: ““We have another situation with dormant bacteria. In this case we find we have to keep hitting it with biocide more and more often. When the bacteria do start to grow again as the biocide level drops, we see huge pH, alkalinity drops within a week and there is often a bad smell associated. I worry that this is partially due to a large population of dormant bacteria (104 CFU mL-1 to 105 CFU mL-1 on paddles) that is able to wake up and grow more quickly. Is there a way to get at these bacteria and kill them to reduce their population?”

With the MWF manager’s approval, today’s article draws heavily on my response to his email.

Dormant cells

Bacterial endospores

Endospores are special structures formed by a few types of bacteria. Endospores are metabolically inactive (i.e., dormant). There have been reports of microbiologists inducing endospores that have been dormant for more than a million years to germinate into vegetative (i.e., metabolically active) cells. Until recently (i.e., the past ~ 15 years), microbiologists believed that only endospore-forming microbes like Bacillus sp. (Gram +, spore-forming aerobic rods) and Clostridium sp. (Gram +, spore-forming anaerobic rods), could survive for long periods in a dormant – metabolically inactive state (Figure 1).

Fig 1.
Fig 1. Bacterial endospores – a) Bacillus subtilis; b) Clostridium tetani. In these photomicrographs, the B. subtilis endospores appear as green spheroids and the C. tetani endospores appear as blue spheroids (sources: a) asmscience.org; b) https://www.researchgate.net).

 

Persister Cells

In the late 1980s, microbiologists started to report on the existence of persister cells – non-sporeformers that seemed to be able to withstand biocide treatment. In some respects, persister cells are like trees that are dormant during the winter but become active as spring arrives. When conditions are unfavorable, these cells become metabolically inactive and can remain in this state for thousands of years. Unlike endospore-forming bacteria, persister cells do not form any special structures.

Understanding of persister cells grew as biofilm research advanced. It turned out that persister cells were often resistant to biocide treatment because they were metabolically inactive – much like endospores but without the unique endospore cell wall chemistry. Thus, the study of persister cells evolved into the study of dormant cells. Thus, the terms persister and dormant are used to describe cells that can become metabolically during tough times and then become active after prolonged periods (1,000s of years) of inactivity. The biology of dormancy and reactivation is still a hot research topic.

Viable but not culturable (VBNC) cells

The rapid development of non-culture microbiological test methods, starting with protein concentration testing in the 1940s, ATP testing in the 1950s, and rudimentary genomic testing in the 1970s (my lab used to test seawater samples for total DNA concentration among other microbiological parameters), led to an awareness that not all microbes were readily detected by culture methods. In 1982, a ground-breaking study focused on a disconnect between the incidence of cholera disease among Chesapeake Bay area restaurant patrons and the inability of the local Department of Public Health to recover the bacterium Vibrio cholera form suspect oyster meat. A post-doctoral fellow at the University of Maryland decided to compare microscope direct counts with culture data. He came of with the idea of treating specimens with a reagent that prevented cell division but permitted cell growth. Metabolically active V. cholera cells would show up as >10x their normal size. Dormant and moribund cells would be visible as normal sized cells. Low and behold, shellfish samples that yielded no culturable V. cholera actually had 106 to 109 metabolically active – i.e., quite viable cells mL-1! That work precipitated an avalanche of research on VBNC microbes.

The term VBNC includes two distinct categories of microbes.

Injured cells – The first category includes cells like the aforementioned V. cholerae that sometimes can be cultured but not reliably. These normally culturable cells are unable to reproduce on or in the growth medium that was designed to detect them if they are injured. Since the early 1980s, process steps have been added to culture test to help injured cells recover before they are cultured for enumeration.

Most types of bacteria – The second category includes microbe we do not yet know how to culture. They do not product colonies on any of the available growth media, under commonly used growth conditions (i.e., temperature, oxygen availability, etc.). Current estimates suggest that for every organism that has been successfully cultured, 1 million to 1 billion that exist in nature have not been cultured.

Metalworking Fluid Microbial Contamination Condition Monitoring

Choosing one or more test methods

If you test a population of people for height and weight you will find that – generally speaking – people’s weight increases with their height (Figure 2a). However, the relationship falls within a cloud around the trendline. Contrast this with the relationship between refractive index (°Brix) and metalworking fluid concentration ([MWF]) shown in Figure 2b. The trend lines in both graphs have the same slope, but the data point spread around the trend line is much greater for the height versus weight plot than it is for the °Brix versus [MWF] plot.

 

Fig 2. Correlations between pairs of parameters – a) human height versus weight (a significant, but weak correlation); b) refractive index (°Brix) versus [MWF] (significant and strong correlation).

 

I’ve discussed this concept in previous What’s New posts (see https://biodeterioration-control.com/microbial-damage-fuel-systems-hard-detect-part-3-testing/, https://biodeterioration-control.com/2019/07/, and https://biodeterioration-control.com/2020/03/)

The relationships among different microbiological test methods reflects the fact, that like Figure 2a, above, each method measures a different property (see https://biodeterioration-control.com/2017/07/).

Each test method tells a story

Between the dormant cell and VBNC cell factors, there are quite a few reasons that culture and non-culture testmethods can tell different stories. In some cases, culture data suggest a greater biodeterioration risk than actually exists (i.e., substantial bioburdens are not damaging the MWF). In others, culture data suggest that there is negligible biodeterioration risk but other data – such as ATP – indicate that the biodeterioration risk is great. This happens when a substantial portion of the metabolically active population is either non-culturable or clumped into masses (flocs) of cells and each such mass (100s to 1000s of cells) forms a single colony. So how do we interpret apparently conflicting data from two different methods. I’ll use culture (CFU mL-1) and cellular ATP concentration ([cATP] in pg mL-1) to illustrate the concepts.

When culture testing indicates high bioburden, but ATP data does not – if the population is dormant in the MWF but becomes metabolically active after being transferred to a growth medium, the population represents a potential risk. It is not causing damage at present, but could become metabolically active at some future point, as I will discuss below. As illustrated in Figure 3, the biodeterioration risk is moderate.

When culture testing indicates low bioburden, but ATP data indicates high bioburden – if a substantial percentage of the population is VNBC but metabolically active, it represents a current risk. Even though culture recoveries are minimal, the population is using MWF components as food and is producing acids and other metabolites that can degrade MWF performance. Per Figure 3, the biodeterioration risk is high.

It should be obvious that when both culture and ATP-bioburdens are low, the biodeterioration risk is low. Conversely, when both culture and ATP-bioburdens are high, the biodeterioration risk is high.

 

Fig 3. Biodeterioration risks based on culture and ATP-bioburden data.

 

Assessing microbicide performance in MWF systems

Based on the preceding background discussion, if microbicide treatments are not having the desired effect, it is important to assess whether the population in the treated MWF is dormant populations or not. because of the MWF dynamics, the available biocide concentration rapidly decreases to less than the critical (i.e., minimum effective) concentration with sufficient speed that bioburdens seem to yo-yo quickly (see the August 2018 What’s New article for an explanation of critical microbicide concentration).

For example, in a system with 10 % turnover per day, fluid loss through turnover rate will drop 2000 ppm biocide to 1,180 ppm in five-days. Add to that biological demand (microbicide consumption as it kills microbes) and chemical demand (microbicide reactions with other organic compounds in the MWF, dissolved metals, and salts, causing the microbicide molecule to either breakdown or become biologically unavailable) and it is easy to see how the concentration of biologically active microbicide can fall to below its critical concentration (1,000 ppm for triazine) within 4 to 5 days.

Dealing with rapidly restored bioburdens

Case 1 – Culturability is affected but [cATP] is not – If the population drops shortly after biocide addition, then the biocide is effective when it is present in the >critical concentration range. If you have a field test for microbicide concentration ([microbicide]), you can do a quick trial to track [cATP], CFU mL-1, and [microbicide] before treatment and at 8h to 12h intervals post-treatment. If the treatment is effective, within 24h the [cATP] should drop by ³2 orders of magnitude. Determine the [microbicide] at which [cATP] begins to climb and the number of days post-treatment it takes for that to happen.

Figure 4 illustrates Case 1. Initial treatment causes both CFU mL-1 and [cATP] to drop as expected. This indicates that the microbicide is effective at recommended end-use concentration. However, over time, both [microbicide] and CFU mL-1 show a seesaw pattern. As the [microbicide] decreases, CFU mL-1 increases. The [cATP] remains unaffected. This indicates that even at 750 mg L-1 (ppm), the microbicide is working as a biostat – keeping most of the population dormant.

 

Fig 4. Microbicide effect on bioburden – Case 1.

 

Case 2 – [cATP] is affected but culturability is not – In this case, the CFU mL-1 is not affected by microbicide dosing. However, there is an inverse relationship between [cATP] and [microbicide]. The [cATP] initially drops in response to 2,000 mg L-1 microbicide dosing but recovers as the [microbicide] falls. Regardless of the [microbicide] the CFU mL-1 remain within the test method’s (paddles) normal variability range (±1 order of magnitude). Figure 5 illustrates Case 2.

 

Fig 5. Microbicide effect on bioburden – Case 2.

 

Case 3 – [cATP] and culturability are affected – In this scenario, illustrated in Figure 6, microbicide treatment causes both parameters to fall. As the [microbicide] decreases, both culturable and ATP-bioburdens recover. Note that after a microbicide addition, the impact on CFU mL-1 is faster than the effect on [cATP]. This is because cell injuries are likely to inhibit culturability almost immediately after treatment. However, it takes longer for cells to actually die. A full effective microbicide treatment will produce data similar to that shown inf figure 6. Keep in mind that Figures 4, 5 and 6 all pertain to a high-turnover system in which dilution is the primary factor affecting the microbicide’s half-life. That said, in systems with low turnover rates (< 5 % per day), the patterns will be similar but the x-axis will stretch out.

Fig 5. Microbicide effect on bioburden – Case 3.

Sorting out the three cases

AxP testing – AxP testing uses ASTM Test Method E2694 for Measurement of Adenosine Triphosphate in Water-Miscible Metalworking Fluids to obtain extracts that include ATP, adenosine diphosphate (ADP), and adenosine monophosphate (AMP). The “x” in AxP is used to indicate that the method tests for all three molecules. Recently, Drs. Peter Küenzi, Jordan Schmidt, and I collaborated to asses the relationship between MWF additives and Adenylate Energy Charge – AEC (see https://biomedgrid.com/fulltext/volume7/adenylate-energy-charge-new-tool-for-determining.001178.php). The AxP data are used to compute AEC. Dormant or moribund populations have AEC <0.5. Healthy populations have AEC ³0.7.

Per the preceding discussion of VBNC and dormant cells, high AEC with low CFU mL-1 signals the presence of an active but non-culturable population. Conversely, high CFU mL-1 and low AEC signals that the microbes recovered by culture testing are not causing damage in the MWF. They are either dormant or dying off, but able to recover in the growth medium. I do not recommend AxP for routine testing. It is useful to make seemingly confusing or questionable data make sense.

Test for biofilm growth and biocide effect against biofilms

Commonly, we ignore biofilms (the November 2017 What’s New article discusses biofilms in fuel systems) growing on MWF system surfaces. Research has shown that both the dose needed to disinfect biofilms is typically 10x that used to kill planktonic – free-floating -cells (See December 2019’s What’s New). Additionally, the soak interval – period of contact – must be at least 24h. Biofilms periodically launch cells into the overlying fluid so that they can be transported to new surface colonization sites.

If you do not periodically eliminate biofilm populations, cells from MWF system biofilms readily reinfect the recirculating fluid as soon as the biocide concentration approaches the critical concentration. This is not an issue of dormant cells or VBNC cells. It is simply a reinfection process.

Use the DSA test method to evaluate biofilm accumulation in the system. If your DSA results are ³103 pg cm-2, you will need to do a full system clean out and recharge before you’ll be able to restore reliable bioburden control.

Summary

Although culture and ATP data generally tell the story, sometimes they do not.

If the population initially responds to microbicide treatment but recovers quickly, the two most likely causes are:

  • 1. Reinoculation from biofilm communities, and
  • 2. Recovery of the planktonic population when the microbicide’s half-life is shorted faster than assumed.

ATP by both ASTM Test Method E2694 & DSA testing can tell you if Cause 1 is at play. If biofilm growth is causing the data pattern you have reported, you will need to do a drain, clean, and recharge to break the cycle.

ATP, culture, & [microbicide] can tell you if cause 2 is at play. If short half-life is the issue, you’ll have to rethink your dosing plan.

AxP can tell you if there is a dormant population affecting your test results.

For more information, contact me at fredp@biodeterioration-control.com

Minimizing Covid-19 Infection Risk In The Industrial Workplace


Electron microscopy image of the SARS-CoV-2 virus.

 

COVID-19 Infection Statistics

Although anti-COVD vaccines are rolling out and people are being immunized, as of early late December 2020, the rate at which daily, newly reported COVID-19 cases has continued to rise (Figure 1). In my 29 June 2020 What’s New article I discuss some of the limitations of such global statistics. In that post, I argued that the statistics would be more meaningful if the U.S. Centers for Disease Control’s (CDC’s) morbidity and mortality reporting standards were used. Apropos of COVID-19, morbidity refers to patients’ cases reported and having the disease and mortality refers to COVID-19 patients who die from their COVID-19 infection. Both morbidity and mortality are reported as ratios of incidence per 100,000 potentially exposed individuals. I illustrated this in my portion of an STLE webinar presented in July 2020.


Fig 1. Global incidence of new COVID-19 cases – daily statistics as of 23 December 2020 (source: coronavirusstatistics.org).

 

What Do the Infection Statistics Mean?

Social scientists, epidemiologists, and public health specialists continue to debate the details, but the general consensus is that the disease spreads most widely and rapidly when individuals ignore the fundamental risk-reduction guidelines. It appears that COVID 19 communicability is proportional to the number of SARS-CoV-2 virus particles to with individuals are exposed. Figure 2 illustrates the relative number of virus particles shed during the course of the disease.


Fig 2. Relationship between number of SARS-2CoV viruses shed and COVID-19 disease progression.

 

Notice that the number of viruses shed (or dispersed by sneezing, coughing, talking, and breathing) is quite large early on – before symptoms develop fully. It’s a bit more complicated than that, however. Not all infected individuals are equally likely to shed and spread the virus. All things being apparently equal, some – referred to as super-spreaders – are substantially more likely than others to infect others. Although people with or without symptoms can be super-spreaders, those who are infected but asymptomatic are particularly dangerous. These folks do not realize that they should be self-quarantining. A study published in the 06 November 2020 issue of Science (https://science.sciencemag.org/content/370/6517/691) reported that epidemiological examination of millions of COVID-19 cases in India revealed that 5 % of infected people were responsible for 80 % of the reported cases.

What Shall We Do While Waiting for Herd Immunity to Kick-In?

The best strategy for avoiding the disease is to keep yourself physically distanced form others. Unfortunately, this advise is all but worthless for most people. We use public transportation to commute to work. We teach in classrooms, work in offices, restaurants, medical facilities, and industrial facilities in which ventilation systems are unable to exchange air frequently enough to minimize virus exposure risk. The April 2020 ASHRE Position Document on Infectious Aerosols recommends the use of 100 % outdoor air instead of indoor air recirculation. The same document recommends the used of high-MERV (MERV – minimum efficiency removal value – 10-point scale indicating the percentage of 0.3 µm to 10 µm particles removed) or HEPA (HEPA – high efficiency particulate absorbing – able to remove >99.9% of 0.3µm particles from the air) filters on building HVAC systems. Again, as individuals who must go to work, shop for groceries, etc., outside our own homes, we have little control over building ventilation systems.

Repeatedly, CDC (Centers for Disease Control), HSE (UK’s Health and Safety Executive), and other similar agencies have offered basic guidance:

1. Wear face masks – the primary reasons for doing this is to keep you from transmitting aerosols and to remind you to keep your hands away from your face. Recent evidence suggests that that although masks (except for ones that meet N-95 criteria) are not very efficient at filtering viruses out of the air inhaled through them, they do provide some protection.

2. Practice social distancing to the extent possible. The generally accepted rule of thumb is maintaining at least 6 ft (1.8 m) distance between people. This is useful if you are in a well-ventilated space for relatively short periods of time but might be insufficient if you are spending hours in inadequately ventilated public, industrial, or institutional spaces.

3. Wash hands thoroughly (at least 30 sec in warm, soapy water) and frequently. The objective here is to reduce the chances of first touching a virus laden surface and then transferring viruses into your eyes, nose, or mouth.

Here are links to the most current guidance documents:

CDC – How to Protect Yourself and Othershttps://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/prevention.html

CDC – Interim Guidance for Businesses and Employers Responding to Coronavirus Disease 2019 (COVID-19), May 2020https://www.cdc.gov/coronavirus/2019-ncov/community/guidance-business-response.html

HSE – Making your workplace COVID-secure during the coronavirus pandemichttps://www.hse.gov.uk/coronavirus/working-safely/index.htm

UKLA- HSE Good Practice Guide – http://www.ukla.org.uk/wp-content/uploads/HSE-Good-Practice-Guide-Sept20-Web-LowresC.pdf – discusses health & safety in the metalworking environment.

WHO – Coronavirus disease (COVID-19) advice for the publichttps://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public

Remember: Prevention really Means Risk Reduction

It is impossible to reduce the risk of contracting COVD-19 to zero. However, timely and prudent preventative measures can reduce the risk substantially so that people can work, shop, and interact with one another safely. Guidance details continue to evolve as researchers learn more about SAR-CoV-2 and its spread. However, the personal hygiene basics have not changed since the pandemic started a year ago. If each of us does our part, we will be able to reduce the daily rate of new cases dramatically, long before the majority of folks have been immunized.

For more information, contact me at fredp@biodeterioration-control.com

METAWORKING FLUIDS, 3RD EDITION NOW AVIALABLE!

Thirteen years after Metalworking Fluids, 2nd Ed. was published, the third edition is now available. Metalworking Fluids, 3rd Ed. Jerry Byers, Ed. has just been published (ISBN, Hardbound: 978-1-4987-2222-3; E-book: 978-1-14987-2223-0) and is available from STLE, CRC Press, or Taylor & Francis.

MWF 3rd. Ed. promises to become the new MWF bible. All of its chapters reflect either substantial updates or all new material. I recommend this new volume most strongly to all metalworking industry stakeholders.

Full disclosure, I wrote Chapter 11 – Microbiology of Metalworking Fluids. Many of the other chapters were written by colleagues on STLE’s Metalworking Fluid Education and Training Subcommittee.

PROTOCOL FOR DIFFERENTIATING BETWEEN BACTERIAL AND FUNGAL ATP NOW PART OF ASTM E2694

ASTM E2694, Method for Measurement of Adenosine Triphosphate in Water-Miscible Metalworking Fluids, was first approved in 2009. The 2016 revision of the method has just been published by ASTM (www.astm.org). This version includes a new Appendix X4 that provides a protocol for differentiating between bacterial and fungal contamination in metalworking fluids. I had first written about this protocol here in my 04 May 2015 blog. The original research on which the ASTM E2694 revision was based was published in 2014: Passman, F.J. and Küenzi, P., “A Differential Adenosine Triphosphate Test Method for Differentiating between Bacterial and Fungal Contamination in Water-Miscible Metalworking Fluids” International Biodeterioration & Biodegradation (2014), http://dx.doi.org/10.1016/j.ibiod.2015.01.006 0964-8305.
Appendix X4 is meant to be used only on samples that have high cATP concentrations as determined by the basic E2694 test. I generally consider ≥1,000 pg/mL to be high cATP, but others might choose to be more conservative. The differential method guides microbicide selection. If the ATP-biomass is all from bacteria, then a tankside addition of bactericide is generally the appropriate treatment. If it is from fungi, then a fungicide will be needed. A broad-spectrum microbicide or compatible bactericide and fungicide are needed to control an infection that is due to a combination of bacteria and fungi. For more information, contact me at 609.716.0200 or fredp@biodeterioration-control.com.

WHERE HAVE ALL THE MICROBICIDES GONE? LONG TIME PASSING…

How many of you recall the Bob Seeger song: Where have all the flowers gone? It seems that it might be time to modify the lyrics by replacing the word flowers with biocides approved for use in metalworking fluids (MWF). I admit, that’s a mouthful, but the reality is comparable to that behind the original song. The list of active substances for which Biocidal Products Regulation (BPR) dossiers have been submitted includes a mere 27 actives intended for use in MWF. Less than 10 years ago, there were more than 100 options. The dust hasn’t yet settled in the USA, but once the US EPA’s Office of Pesticides Programs rules on the maximum permissible dosage of triazine in MWF later this year, it’s likely that the ASTM E2169, Table 2 list of active ingredients approved for use in MWF will be a fraction of its original length. Perhaps, when compared with our European friends, we are still lucky in the USA. A literal reading of the BPR’s definition of a Biocidal Product suggests that all MWF are Biocidal Products. The UEIL is advocating that MWF be formally recognized as Treated Products (the cost impact is an estimated $250,000 U.S. per MWF formulation – not trivial). Regulators have promised to give UEIL’s arguments full consideration, but nothing has yet been put in writing. I reviewed the latest state of affairs in my January 2016 TAE presentation. Please contact me if you are interested in receiving a copy of the manuscript: Impact of Biocidal Product Regulation on Microbial Contamination Control in Metalworking Fluids.

Using ATP to evaluate biofilm dispersants.

If you will be attending the STLE Annual Meeting on 15 through 19 May 2016, be sure to join me at the Metalworking Fluids Technical Session III, in the Silver Room, Bally’s Las Vegas, NV. At 0830h, on Tuesday 17 May, I’ll be presenting my paper: “Adenosine Triphosphate Testing to Evaluate Biofilm Dispersants.” The paper discusses the use of LuminUltra Technologies Limited’s QGO-M and DSA test methods to compare the efficacy of a number of different formulations for removing biofilm from pipe surfaces without being biocidal. As regulators increasingly restrict the use of MWF microbicides, it is becoming increasingly important to develop non-biocidal biodeterioration prevention strategies. My STLE presentation will speak directly to this issue. I’m looking forward to seeing you in Las Vegas. Please contact me directly (see “REQUEST INFORMATION” on BCA’s home page) if you would like to schedule a conversation during the STLE Annual Meeting.

The Truth is Out There…

For those of you who are interested in metalworking fluid microbiology and microbial contamination control, I invite you to read my March 2016 Tribology and Lubrication Transactions TLT) article: MWF Biocides Part II – Science vs. Fiction.
This was an accidental article that I was asked to write in response to an error-laden article that had appeared in TLT’s November issue. The earlier piece had been written by an individual whose familiarity with the topic was limited to the research performed in the process of drafting the TLT submission. I had not yet read the article when I started receiving flaming emails from industry colleagues who mistakenly believed that I had an editorial role and had somehow approved the article for publication. Initially, my plan was to write a letter to the editor. Indeed, I wrote a draft letter listing each error and the correct information (with relevant references cited as appropriate). The letter morphed into the March article. To be sure that I wasn’t just offering my personal opinions, I recruited log time colleagues Drs. Neil Canter and Alan Eachus and Mssrs. Jerry Byers and Richard Rotherham to co-author the article. I am much indebted to each of them for their contributions to the effort.
MWF Biocides Part II focuses primarily on the scientifically unsupportable conflation of formaldehyde (HCHO) and formaldehyde-condensate microbicides (FCM). The toxicological profiles of FCM differ among specific chemistries, but as a group are substantially different from HCHO. Moreover, although regulators assume that 100% of the HCHO in FCM will end up in the air above metalworking fluids (MWF) threated with FCM, data prove otherwise. Over the past couple of years, the number of microbicides approved for use in MWF has plummeted. In Europe there are only 27 listed biocidal substances (most are still going through regulatory review) that can be used in MWF. In the U.S., by last summer, the US EPA’s Office of Pesticides Programs will most likely issue guidance that will determine the future availability of FCM. In addition to clarifying the FCM issues that had been misreported in the November article, the March article sets the record straight on nearly 30 other misstatements made in the earlier publication.
Please contact me at fredp@biodeterioraiton-control.com for a copy of the MWF Biocides Part II.

Legionella pneumophila in Metalworking Fluids

I’m sharing an email exchange that I had with a colleague who had asked about the risk of L. pneumophila (the microbe that causes Legionnaire’s disease) in MWF.
Thank you for posting your query to BCA’s website.

You wrote:
“I wondered if you could help me answer a customer’s question. One of my customer’s machine tool operators is in the hospital being treated for Legionnaires’ disease. My customer asked me if the Kathon 886 MW or Kathon CC kills this strain of bacteria. I really appreciate your help and advice. I attend the annual STLE meeting every year and hear you speak on maintaining and monitoring metal working fluids, so I thought you would be the best source to ask. The Legionnaires’ disease was most likely contracted in Tennessee while this gentleman was on vacation. Other machine operators are now afraid they might contract the disease through the metal working fluids in the plant.
Thank you for your time and thoughts.”

The short answer is yes.

Not long after Legionella pneumophila was identified as the disease agent that caused Legionnaire’s disease, Rohm & Haas tested Kathon WT1.5 efficacy against the bacterium. WT1.5 is just Dow’s (formerly R & H) water treatment market label for the 1.5% active product we use as Kathon 886MW and 886MW 1.5 in the MW industry.

Keep in mind that L. pneumophila is ubiquitous. If you recall the incident at Ford’s Le Brea, OH plant some years ago, four machinists came down with Legionnaire’s disease. Attempts to detect L. pneumophila from MWF systems all failed. An immunological survey of all of the plant’s employees revealed that the majority has antibodies to L. pneumophila. Other immunological surveys (populations outside our industry) have demonstrated that the majority of the population has been exposed to the microbe (i.e.: has the antibodies). Most of the time, folks who contract the disease have other health problems that render them more susceptible than the general population. Back to Le Brea. That incident and a cluster of Pontiac Fever cases at a Pontiac Plant in Windsor Ontario in 1981 are the only two clusters of Legionnaire’s disease that have been reported in the MW industry. The 1981 outbreak was caused by L. feeleii growing in the facility’s cooling towers. The source of L. pneumophila at Le Brea was never confirmed.

From what we know, workers are much more likely to be at risk from improperly controlled heat exchange systems/cooling towers than from MWF.

What’s New – June 2014

In January 2014, at TAE’s 19th Tribology Colloquium, I presented th preliminary results of field evaluations that were being performed on LuminUltra Technologies dQGO-M test method. The new ATP test method provides a simple and reliable means of differentiating between fungal and bacterial contamination in metalworking fluids (MWF).

Four international MWF compounders participated in the field evaluation. All of their data were subitted in time for my STLE 2014 Annual Meeting Presentation:

Recent advances in the differentiation between fungal and bacterial contamination in metalworking fluids using modifications of the ASTM E2694 Standard Test Method. Read more…

What’s New – November 2013

On March 11 through 14, 2014, Dr. Neil Canter, Mr. John Burke and I will once again be presenting STLE’s Metalworking Fluid Certificate Training Course. The course will be held in Atlanta, GA. For more information, visit the STLE website…

In January, 2013, at TAE’s 9th Fuels Colloquim, I presented a paper describing modifications of ASTM Mehtod D7687 (ATP in Fuel) that permitted detection of dormant microbes possibly present in fuel samples, and differentiation between bacterial and fungal biomass in fuel and MWF samples. In October, 2013, at the 13th International Symposium on the Stability and Handling of Liquid Fuels, I presented an updated version of the TAE paper.

In June 2013, I was honored to be presented with ASTM’s Award of Merit.

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