Mary:
I'm Mary Parker, and welcome to this episode of Eureka's Sounds of Science.
One of the most important issues once a drug has been approved is the continuous monitoring of safety. It's not enough for regulators to approve a drug and send it off into the world unsupervised. Manufacturers have to maintain constant vigilance to ensure patient safety.
Today I'm joined by Charles River Senior Principal Scientific Advisor Miriam Guest and independent microbiology and sterility assurance consultant Vanessa Figueroa. When it comes to the safety of injected drugs, they know the past, they understand the present, and they can predict the future. Welcome, Miriam and Vanessa.
Miriam Guest:
Hello.
Vanessa Figueroa:
Hello. Thanks so much for having me.
Mary:
Thank you so much for being here. I'm really excited about this discussion. So let's dive right in. Can we start with your backgrounds? Miriam, how did you get into this line of work?
Miriam Guest:
I studied in the UK. And in the United Kingdom we have GCSEs and then A-levels. I think that's the same as freshman and sophomore year in the US. During my A-levels, I picked science-based subjects. I did biology, chemistry, and maths. And I really fell in love with biology at that point. So I went off to university in Liverpool and studied microbiology for three years. I did a bit of genetics as well, but that was really what piqued my interest. I found a love for the bugs, and I think that stayed with me.
So after university, I moved for love. I met my husband at university and I moved to where he lived. And I was very fortunate to get a job with AstraZeneca, starting my career as a microbiology lab technician in pharmaceutical development. So yeah, that's how it all started. And I have to say I still love the bugs after all this time.
Mary:
Did you have a career end goal in mind, a job you wanted, or did you just follow the academic interests that you wanted to?
Miriam Guest:
Oh, definitely followed the interests. And then I think they say you make your own luck, but I feel that I did get some fortunate opportunities on the way that I took with both hands. Like I spent a few years as a facility microbiologist in manufacturing, which was a fantastic education and learning. And if you'd have asked me if I'd have been in a manufacturing type role when I was 18, I wouldn't have thought that could have happened, but I'm so glad it did now because I use that learning every day.
Mary:
Yeah, absolutely. I don't think people really appreciate how fascinating manufacturing is, especially for things like drugs where it's like 90% science, 10% factory automation, or whatever the percentage might be. It can get really, really interesting.
Miriam Guest:
Yeah, I still miss getting out there on the facility floor. I think there's a really nice... It's almost a freedom because it's such focused work, you're so focused on being disciplined and following the good aseptic practices, it's almost like yoga in that mindful space that, yeah, I do kind of miss it.
Mary:
And how about you, Vanessa? What's your background? How do you become an independent microbiology and sterility assurance consultant?
Vanessa Figueroa:
Yeah, it's a great question. Before entering university, I always had a passion for biology. And just, I think you hear this a lot with people in our space, just fascinated with the human experience, the human condition, and how it functions.
I was already very keen on the track for biology and really understanding really medical conditions and how things interact and how we can manipulate the body or provide medicines or change things in the human body at a very early age, so always doing doctor-patient scenarios with my family.
So I knew going into university that I would major in biology. I went to a specific university for cell molecular biology. When I entered university, the human genome, the same year, had just been sequenced for the first time.
Mary:
Oh, wow.
Vanessa Figueroa:
Yeah. And it was a perfect opportunity to just dive deep into... I literally remember the first week of freshman biology, we had to get a book reprint. We purchased our books and they had to reprint them a month into school because of the human genome and the updates to the molecular biology.
Mary:
Whoa.
Vanessa Figueroa:
Yeah, it was really cool. It was fascinating. So I was on the track for cell molecular biology and biotechnology. That was my major going into the university. But partway through my career, I got pulled aside by my microbiology professor to do a summer research program that was funded by NASA at the time to study the effects of modeled microgravity on human T-cells, Jurkat T-cells.
And that just sort of immersed me into a lot of PCR and western blots and a lot of the very lab-specific methodologies and just understanding immunology and biology at a very molecular level. So that sort of changed my heart and really my professor's influence and interest in me and helping to develop me and my skills was really sort of redirecting me towards a more niche path in molecular microbiology.
So I graduated university. And I too, Miriam, relocated for love. I had my current husband, we've been together 23 years, he and I were together. We met at undergraduate university and he got a job opportunity in California in the Bay Area. And so off we go. This is exactly 20 years ago this month. Off we go, two very young scientist and engineer to the Bay Area.
And shortly after, I got my first opportunity with Abbott Laboratories in the microbiology lab, and that just solidified where I needed to be in microbiology, in manufacturing, just realizing how much influence and how much practical science was in this space. I didn't know that when I was in university that there's a practical industrial side of microbiology, that you could be doing this every day, you could make a living off of it. So that was really intriguing.
And then sort of like Miriam just progressed throughout the industry from there. So I pursued advanced study, a master's degree in molecular microbiology, and then about a decade into my career made the jump into being an independent, which needs its own podcast to describe in further detail. But it's been great. Yeah, so it's been over a decade.
Mary:
That'll be part two.
Vanessa Figueroa:
Right, part two. It's over a decade I've been independent. And let me tell you, it's allowed me to be all over the world, all different types of products, medical device, and really give me a world of experience that I can contribute and bring back to each of my clients and projects every day.
So it's been a wonderful journey. Highly recommend it. It's thrilling. And, Miriam, it does allow us to still be in the manufacturing floor. I was there last week. So it gives you that itch that we have as industrial microbiologists to be on the floor. And so I'm really happy being an independent and being in this space.
Mary:
You can't poach Miriam live on the podcast to join you. Just kidding. Totally.
Vanessa Figueroa:
That's hilarious. I'm just telling her that you still have the opportunity to go back into manufacturing, even she does too in certain projects. So absolutely. She's client facing, so it's a great place to be.
Mary:
It sounds like both of you have a really wide-ranging background, and you've filled a lot of different roles, which is perfect. So you can speak to a lot of different aspects of our topic today, which I love that. So let's, over to you, Vanessa. I know you taught some microbiology courses for the US Pharmacopeia recently. How were your teachings received?
Vanessa Figueroa:
Yeah, so I partnered with the USP to teach five different courses in their microbiology compendial chapters. They were fantastic. So one of the first ones we kicked off were sort of a preview for the new stability testing chapters, USP 72 and 73. And they were very well received, very well attended. Lots of fantastic questions. I think that those specific chapters are a long time coming, and so people were really eager to receive that content. And then the subsequent courses-
Mary:
Uh-huh. Could you just give us a little background on what those are? Thumbnail sketch?
Vanessa Figueroa:
Yeah, sure. So USP 72 is on the respiratory-based methods for sterility testing, and 73 are on the ATP bioluminescence-based methods for sterility testing. So they're different than the traditional USP 71, which is the culture-based method, which we'll talk about in great detail. I don't want to steal any thunder from the rest of the podcast. But yeah, so they're just offering new compendial ways for you to perform validation of those alternates.
Mary:
How did current regulations regarding drug manufacturing safety come about? Because I know that we didn't always test these things. They were kind of, I assume, on the companies to say that they were safe.
Vanessa Figueroa:
I was doing a little bit of thinking to prepare for this and doing a little bit of a historical deep dive. And I'll tell you what I've found is that similar to, and maybe this just mimics general human behavior, but drug manufacturing regulations are almost always born out of a tragic situation or out of failure, right? They're usually quite public. They usually involve the death of human lives.
And some of the very early pivotal moments in US history were like a disaster in 1937. Over a hundred people died taking a certain elixir, Sulfanilamide, and there was a toxic solvent used. And there weren't requirements for drug safety, for drug safety testing. This is one of the initial historical contexts for the Food, Drug, and Cosmetic Act, which is what we have in the US, to mandate pre-market safety review and regulations.
But later in the 1940s and the 1950s sterile injectable products, we hadn't tested them for safety using microbiological safety parameters. And there were widespread outbreaks of septicemia, people dying because we didn't know what we didn't know about the way that these products were contaminated. These events in the '40s and '50s eventually led to the development of sterility testing requirements, various process controls.
There was a specific event with thalidomide. I'm sure that everyone in our industry remembers this specific tragedy. It was in Europe and it caused some severe birth defects, and there were a lot of additional efficacy requirements, tightened GMPs, et cetera. So I think that there were specific regulations both in the US, the EU's GMP directives, that are really rooted in understanding the product, understanding which attributes of the product need to be tested for. In the case of sterile injectable products, what does that test look like? Well, it became what we currently know as sterility testing.
And that's really just a high-level overview, but really this concept of early in drug manufacturing there were significant events. And I think one of the most recent one is what we've experienced in the injectable compounding industry back in 2012. That really rocked the world. The example of the New England Compounding Company, that was something that the whole industry wasn't aware was happening at the rate that they were compounding injectable products going into people that had mold contamination.
And even something as recent as 2012 having a tragic situation then lead to refinement of the GMPs and the Food and Drug Cosmetic Act for the GMP compounding space. So I think that there's a thread there. I'm really glad that we're in the place that we are now where we do have these safety, efficacy, and quality parameters that are tested into, but that's just a little bit of some of the history.
Mary:
I love the history of science and medicine. And, Miriam, I'm curious, is the thalidomide story something that is still taught at your higher level when you were in school?
Miriam Guest:
It was definitely part of my GMP training when I started working in the industry, and also the history of how regulations evolved and developed. I actually have a relative that was impacted by that, so it's a topic close to my heart. And I think it's a reminder that these rules and regulations, they're not for fun. We're not doing environmental monitoring for fun. We're not doing sterility testing for fun. We're doing it to protect the patients.
I think just to build as well on Vanessa's comments around the USP, there's a slight difference in how the European Pharmacopeia acts in Europe compared to the USP. So from what I understand, and Vanessa, you might be able to correct me, the US FDA can enforce the USP monographs.
Vanessa Figueroa:
Correct.
Miriam Guest:
But in the Europe, the European Pharmacopeia is mandatory for the member states. And I think that's a slight difference, that it's almost a law in Europe, and it's an enforced monograph. I don't know if I explained it very well, but.
Vanessa Figueroa:
To clarify, Miriam, the rooted law are our code of federal regulations, and there it says, "You must not have objectionable microorganisms. And for sterile products, they must not be there at all." So the Compendial Act to provide technical clarity and guidance on how to execute certain methods and the manner in which the method is executed, that's enforced, but the root of our aseptic processing guidance and our code of federal regulations, those are our GMPs, and those are law, and those are enforced.
Mary:
So how has sterility testing for injected drugs historically been done?
Miriam Guest:
Yeah, I guess back in the olden times, there was none. And then the traditional sterility test has been around, I think, since 1912, and it was a direct inoculation culture-based method. But I think advancing time to result and earlier detection for microbiology isn't a new thing. I think right from the 1800s, early founders of microbiology we're looking at faster ways to observe or calculate or identify microorganisms. And there's some really interesting papers from back in the 1880s that look to that end.
ATP bioluminescence is one example of how you can get a faster result. So the traditional method, you have your product in a broth or you membrane filter it, and you have any residual microbes left behind in the media. Then following an incubation period, you simply look at that canister or that broth unit for turbidity, for signs of microbial growth.
And that can be in different forms. Different organisms will grow in different ways in different broths. One of my favorite USP chapters, USP 1117, talks about data integrity in the micro lab, and that really recommends that people are doing a second check of the sterility test. So not just one set of eyes, a second set of eyes look at it.
Now, I've got questions on how efficacious that is. If you've got two people, perhaps it's me and Vanessa, we're working in the lab together, but we were at a party last night and we had a late night, and we've got 40 sterility tests to look at. And I'm pretty comfortable, Vanessa's a great technician. She's been looking at sterility tests for a long time. She knows what she's doing. So maybe I'm not paying as much attention today because I'm pretty sure Vanessa's going to catch it.
However, Vanessa stayed up later than I did. She thinks that I'm on the ball that day. I think that she is. And you can see a risk there that this could... It's not unreasonable that that could happen. So I think there are better ways to measure the presence of microbes rather than relying on visual sterility assessments.
Vanessa Figueroa:
Yeah. Well, for the record, I'd go to any party with you, Miriam. I'd also work alongside you in any laboratory, just not in that sequence.
Miriam Guest:
Yeah, we can do the partying at the weekend.
Vanessa Figueroa:
Yeah. Mary, I think that Miriam captures historically how it's been done. But in addition to what she says, we've always, at least in the microbiology space, we've always had this historical gut feeling that the method is inherently limited. This culture-based method is inherently limited. There's a couple limitations.
So the first limitation is in the sampling. Our ability to test if the product that is sterile filled into a container is indeed sterile. We can still only do that. We still have an inherent issue that it's probabilistic, meaning that you're only still testing a small volume or a small representation of the entire batch. And that's always at the bottom of a gut of a microbiologist as like, "Oh, it's not as statistically sound as we'd like it to be." It's a destructive test, so you're never going to be able to resolve that.
But, Miriam, there is a lot that we can do to strengthen the current technology that we are using for sterility testing. It's still a method that's heavily dependent on operator technique, like the technician. The environment is important. Like Miriam mentioned, a lot of people do recommend moving towards the sterility testing isolator so you limit the amount of false positives. That's really important so that what you're testing reflects the batch quality.
There's a time lag. So in what world does anything take 14 days anymore? Certainly not in 2025. But sterility testing still does if you do it to the traditional culture-based method. And so these start to become an issue when we've got drug shortages, when we're in the middle of a pandemic and we need vaccines faster than we ever thought we would.
And the climate of drug product manufacturing is changing. It's truly changing. And so we ought to change in step with it. And I think what's great about this podcast today, and really some of the newer methods for sterility testing, is it allows us to reduce that time lag, it allows us to analyze the sample using a different microbial attribute. And so it's reducing the risk that Miriam talks about that we went to a party and really had a blast. It's reducing the risk of sample management and operator error when we start to introduce different types of technologies.
Mary:
Yeah. No, that makes sense. So we've touched on this a little bit, but we haven't really defined it. What is ATP bioluminescence testing? How does it work?
Vanessa Figueroa:
So, Miriam, I want to give an example that is very, very high level. And then I think you, because you're the expert in this space, probably can say it much better. But I was thinking about how to explain this to my husband who's a software engineer, a non-micro person, a non-biology person.
Mary:
Right, right.
Vanessa Figueroa:
And I basically told him, I'm like, "It's like microbial forensics with a glow stick." Perhaps let's continue with our party theme, right? So you've got a glow stick in the dancing area. That's what ATP bioluminescence is. It's microbial forensics with a glow stick.
So we know ATP, which is adenosine triphosphate. It's a molecule that's found in every living cell. Bioluminescence testing uses an enzyme called luciferase that reacts with the ATP to produce a light. It glows, essentially. And so very simply putting, the more ATP you have, the more light you have, which is an indicator of the more contamination you have, so biological contamination.
And I think that that's a really high level, good way to put it to someone who's not in a micro space. And I'm sure that Miriam, she could say it a bit more elegant, but the glow stick thing had me having quite a laugh with my husband.
Mary:
No, I love that. I love that. But what say you, Miriam?
Miriam Guest:
I think Vanessa explained it perfectly. Yeah, the ATP is the energy giver in a cell. So a viable cell will be producing ATP and generating that. So this luciferase reaction is actually it comes from glowworms. So you know how glowworms glow in cage? That luciferase enzyme catalyzes it and causes this presence of light.
The other thing that we can do as well is amplify that by adding additional enzymes. So that you'd have your contaminated sample, you'd place that in a test tube, and you'd automatically add the reagents necessary. But those reagents steps will burst the microbial cells effective almost, and allow that ATP to come out into the liquid, and then it's amplified by an additional reagent. And that amplified light generates this light signal, which we can measure light signals and intensities and look at those relative light units to give us a level that indicates the presence of viable microbes.
Mary:
That makes sense. I mean, you might miss a lone firefly in a field, but you're not going to miss a Kmart in the middle of a dark parking lot. So have there been any regulatory hurdles globally for accepting this kind of testing?
Vanessa Figueroa:
Sure. I think it depends on your regulatory body. I think it depends on timing. But I think that the general hurdle, which is with any alternate micro method, be it a rapid one or just a different way of testing other than what has been traditionally done, regulators expect equivalency or superiority to what's an already established compendium method, right?
So for a method like ATP bioluminescence or even a growth-based RMM method, you need robust validation data, you have to demonstrate sensitivity, specificity, repeatability, ruggedness. These are some of the method validation parameters we use in microbiology. I think vendors are aware of this. Vendors have been in front of this for years. They're providing primary validation data. They've been doing this to support clients, holding their hand through implementation of these methods.
I think people are just becoming more comfortable with it, and they're seeing compendial chapters in FDA. And these are just widespread methods, and I hope that there's an increased adoption of them. So I think that the hurdles have been historically in place, but they're slowly starting to dismantle and people are really getting on board.
Miriam Guest:
And I think the regulators, as well, are keen to embrace new ways of working. We certainly see that in the new Annex 1 where it talks about driving technology forward. In the UK we have the Medicines, Healthcare products Regulatory Agency, the MHRA, and they have what's called the Innovation Center. So the Innovation Center, I've had really good experiences with.
You go with a new idea or a new way of working and a proposal of how you would validate this. Perhaps you share some data at that point. And you're looking for that engagement with the regulator to understand their views of, "Do you need additional data? Do you need another thought process on this?" And like I mentioned, those experiences have been really good. The agency's really engaged. It's a lot more relaxed than an audit situation. It's quite an open discussion, and they seem keen to have them.
And I know the FDA has a similar program. I think it's the Emerging Technology Program in the US. And the EMA also has something similar. So there are ways and mechanisms to do it. And we see our regulators at trade shows and events and conferences, and all the conversations I've had with them, they've been really positive about looking at a new way of working, with always the appropriate scientific rationale.
Mary:
So do you feel like the microbiologist can be overlooked when it comes to manufacturing?
Vanessa Figueroa:
Mary! Mary! Yes! I don't know, I think Miriam should go first. But yes, yes, yes. This is the story of our life. It's getting better though, but yes. Miriam, what do you think?
Miriam Guest:
I think I agree it's getting better, but there's definitely... So there's been parts of my career where I'm like, "Just listen to the microbiologist." Like I mentioned with that example of a one-colony forming unit on a settle plate in a Grade A, it's like listen to the small things, listen to the microbes. If you don't, they can cause chaos.
Mary:
Well, if the person who in charge of the microbiology for a manufacturing process doesn't have a Vanessa on site to help them-
Vanessa Figueroa:
Or a Miriam.
Mary:
Or a Miriam. How can scientists better advocate for what they need in the industry?
Vanessa Figueroa:
Yeah, it's a great question. I think what I try to teach in all of my engagements, whether they're at trade shows or client sites or in regulatory conversations or a compendial setting, is we need to connect the science to the business. We can't just say, "Oh, I need a better EM method," or, "I need more equipment or more fancy tools in my lab." A lot of the conversations we've historically had are like, "Look at me, look at me. I'm overlooked. I need more money." But you can't say that without connecting it to the business, without speaking the language of the people who need to approve your capital expenditures.
Mary:
Right.
Vanessa Figueroa:
Right? You need to think about how do you articulate that? How will this improve inspection readiness? How will it reduce batch reduction risk? How will it improve the conditions of the clean room? How will us be able to release to market faster? There's a lot of different conversations. I think that scientists need to be better advocates for the business and for the compliance.
And I think if you're advocating for a new rapid method, like if you're listening to this podcast because you want to know how to implement ATP bioluminescence, you need to go there with a cost-benefit model. You need to align with cross-functional people throughout your organizations, and you need to get them on board on why this is better for the business. It's not just about Vanessa wanting ATP because it's cute and fun. It's about getting the result faster and more precise. It's going to be better for the business. So I think that that's important.
Mary:
Well, there's nothing that bean counters love more than beans to count. And who better to provide hard data on the cost-benefit analysis of these methods than scientists?
Vanessa Figueroa:
Amen.
Mary:
Do the math kids!
Miriam Guest:
Yeah, I'm on that soapbox with Vanessa. I think one thing with the cost-benefit, we've heard of customers that one of the biggest cost-benefits of adopting ATP bioluminescence was reducing manufacturing downtime. So with a product that makes the media turbid inherently and makes it hard for visual determination of is it product or is it organisms? What is it?
If there was doubt, and they thought that perhaps it was organisms, but they weren't quite sure they would stop manufacturing until they'd investigated. So that would be subculture steps, there'd be analytical testing to understand is it product or is it organisms? And they were able to build a business case around the downtime they'd had the previous year because of these stopping manufacture, because the ATP was able to very quickly determine, "This isn't organisms. You don't need to worry."
Vanessa Figueroa:
Mm-hmm, love that.
Miriam Guest:
And they could continue to manufacture. It's a customer, so I don't know the full details, but I believe they still did all the other investigative steps that they always had, but they use it to de-risk continue to manufacture. So that was a nice one for the bean counters because they could really count how much this manufacturing downtime gave them.
Vanessa Figueroa:
Yeah. How cool is that? How cool is that? It makes a good point, Miriam, right? ATP bioluminescence needn't only be for finished product sterility testing. It's a really good way of looking at contamination in a sample, whether that samples from media filling or bioburden or final fill sterility testing. So that's really cool. Thanks for sharing that.
Mary:
Well, and thank you both for sharing your knowledge here on this podcast today. We really appreciate hearing the minutia of how these drugs are tested to keep us safe.
Vanessa Figueroa:
You got it.
Miriam Guest:
Thanks, Mary. And thanks, Vanessa. It's always great to catch up with you.
Vanessa Figueroa:
Yeah. Miriam, thank you so much. And thanks for being such a huge advocate for our space. I always love working with you. Thanks, Mary, so much. You're really fun.
Mary:
Thank you.