Bacteria in the Bulk Tank - Case Studies

This extra special bonus episode from our chat with Dr. Cathy Bauman (Ontario Veterinary College, Guelph, Ontario, Canada) walks listeners through three real-life case investigations. Dr. Bauman describes how she and her team conducted the various outbreak investigations and puts into practice the information she shared with us in the previous two episodes.

Helpful Links:

Luminometer FAQ
https://www.gov.mb.ca/agriculture/food-safety/at-the-food-processor/luminometers.html

Small Ruminant Veterinarians of Ontario
https://srvo.ca/

Dr. Cathy Bauman - Ontario Veterinary College
https://ovc.uoguelph.ca/population-medicine/faculty/Cathy-Bauman

American Association of Small Ruminant Practitioners - find a vet
http://www.aasrp.org/about/find_a_vet.asp

This podcast is sponsored by the American Association of Small Ruminant Practitioners as well as USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Program, Antimicrobial Resistance grant # 2020-04197.

Questions or comments about today's episode can be directed to DairyGoatExtension@iastate.edu

Transcript

Michelle: 0:04

Hello, I'm Dr. Michelle Buckley from Iowa State University's College of Veterinary Medicine. Thanks so much for joining us on Baas and Bleats, sponsored by the American Association of Small French Practitioners. Just a quick note before we get started. This work is also supported by the USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Program, Antimicrobial Resistance Grant No. 2020-04197, which funds my research on improving antibiotic stewardship in dairy goats to assure food safety and milk quality. As always, if you have any questions about any of our episodes, please email them to dairycoat extension at iastate.edu. I hope you enjoyed today's show.

Cathy: 1:24

Thanks, Michelle, for giving me some extra time to just share a couple of lessons I've learned from some case studies. I know that people want to take the lessons I've learned and directly apply them to their farm or some or farm they're investigating, but they're kind of examples of how to work something up because the bacteria will be different in every situation. But just they're examples of you know some bacteria that originate more at the goat level, some of the equipment level, and kind of some in between. So hopefully you can learn from my stress and errors that I've made and lessons that I've learned. And it's just helped me. I think we can all say that we learn from our mistakes, and and it helps to figure out how things are working so you can advise someone else. And so if we can take that away, that's then I'm the happier for that. So again, farm just remember pathogens are farm-specific, and we can just apply the framework to them. So the first farm that I'm just going to talk about, we were dealing with a producer who historically really had strong milk quality. They were really kind of passionate about the industry and being a good PR person, about everyone being on board with producing high-quality milk and milking properly. So they were really fun to work with and really passionate about getting knowledge about how to further improve. Even though they had really good milk quality, they were really keen to improve it even further. They were participating in our study and had let us know slowly over the previous year. Their numbers had been creeping up past the point where they were comfortable, but definitely not in what I would consider penalty range. And so, on first step, like I said, we did bulk tank culture to kind of know what we were dealing with with respect to pathogens. And it identified Streptococcus at just a mild to moderate low level, and then some other background bacteria. And so, and this is a situation where I say it's really important to talk with your lab because all it said was streptococcus on the bulk tank culture and didn't give us the next class name as to what it was. And so, you know, you can start to make some assumptions just knowing it's strep, but in this situation we are a little bit fooled. So we started to do some composite sampling, identified composites with back to scans over 100,000 and high somatic cell counts. And then within each of those, we ran back to scan and somatic cell count on each goat in those high composite samples. And again, our composites were both halves of each goat and every goat on one side of the parlor, and then moving on to the other side so that we could be efficient with cost. So then we cultured all animals within each of those composites that had high somatic cell count. And we also ran a PCR array, so we ran this new test that our lab was using next to DHI lactinet, and we were exploring this cow array to see how it applied in goats, to see if it needed to be adapted in any way, if the pathogens were the same and what have you. So again, this PCR array identified that there was a strep bacteria, and they knew it was not typically found in goats, so they had a marker for strep, but it wasn't picking up any of the other pathogens typically found in cows, so not uberus, dyslactea, or achalactea. And so it piqued our interest as to what's going on because we knew typically that there's bacteria that grow on goats that are not associated with mastitis in cows. So instead of running the traditional mastitis culture, we did a full culture to explore what this bug could be, and it was found out to be Streptococcus canus, bacteria typically carried by dogs. So this is odd. Why are we seeing a dog bacteria in the goat? So the farm otherwise had very low levels of mastitis pathogens. I think they had one Staph aureus goat and very low levels of quagnegative staph. And so, out of interest, um we then took the PCR array and sampled every goat in that herd to see if the strep canis was showing up in any of the other goats. And 80% of them came back with some level of strep canus in their milk. So, again, very, very odd as to why this was showing up. So we had goats with high somatic cell counts in the strep and low somatic cell counts in the strep. So it may or may not have been causing a large degree of mastitis, but it was definitely causing elevations in some of the goats because they weren't culturing any other pathogen. So, as we talked before, strep uh the coccobacteria are typically originating from the environment when we see them in the udders. And so we're in the goat barn. We started to wonder where they were picking this bacteria up from. So we cultured shavings, other pen surfaces, the dogs, the cats that lived there. And we walked with the producer through the whole barn to see how they were feeding, where they were getting the feed from, how they were cleaning the inside of the barn, and what have you. So, long story short, is on this farm they had three purebred dogs that they bred for yearly litters, and the kennels were located in the goat barn just off to the side of the pens of the goats. And so each morning these kennel shavings were being swept into the first goat pen, first milking pen, and then they would get new shavings in those pens. So the only positive samples that we cultured was the urine and the vulvas of all three of these dogs. So same bacteria that was in the milk of the goats was coming from the vulva of these dogs, and we did some identification things to prove this as well, but I won't go into that. And then just so you know, it's a very common bacteria in dogs, and we have to assume dogs will always shed this, but it was just unusual that all three of the dogs seemed to have it. So whether they picked it up during breeding or it was just within this colony of dogs, we just don't know. But what was suspicious is one of the dogs had lost a few puppies the previous year when they had given birth. And so we decided to treat the dogs for antibiotics that the bacteria was sensitive to, and we got the producer to dump the shaving somewhere else that weren't the goats wouldn't be exposed to. And then we came up with a product that we could dry treat the goats that we knew the streptococcus was sensitive to, and we used an intramammary therapy on them, a dry cow intramammary therapy that was adopted for adaptive for goats. So we can't again comment as to what extent they were actually causing mastitis, but it was a milk quality issue because it was causing bacterial counts and somatic cell counts to go up in the bulk tank. So, again, it's it's not always looking at this from the goat side, but starting at the bulk tank side and working its way back to decide how much of a problem it is for the animals and how we go about targeting them for treatment. So we then cultured the milkers because we were curious about how it was being spread, were the goats simply picking it up from laying on the shavings, and we wondered if it was being passed during milking and tried to culture from the inside of the milkers through the cups, and we hadn't cultured anything back from that to indicate that it was being passed between goats next to each other in the parlor. So, again, not all goats had high somatic cell count that had strep in their udders, um, but it you know, maybe it builds up over time. So, in first parity, maybe it's nothing, and then second and third, perhaps maybe it increases. But for further work, again, research needs to be done in that to know the role that it's playing with mastitis. And just to know it's important to post it. And this producer had always done this, so this is unusual, um, just to prevent these environmental pathogens from entering the teat canal after milking, because as we know, it's still open for a small time period afterward where it's most vulnerable. So, again, this is a very unusual case and rare. Um, only a couple cases have been shown to occur in dairy cattle, and I think in Israel and the United States. Um, but it helps us just to make sure you're always thinking outside the box as to you know what we're expecting to occur doesn't always happen to be um what shows up.

Michelle: 10:01

Wow, that's that's very interesting because I'm sure that I mean plenty of our dairy goat producers have more than just dairy goats. You know, you go outside in the morning to do chores and you're feeding dogs and taking care of chickens, and oh, you gotta milk the goats. So I hope that this triggers people to think about their morning routine and their cleanliness and the way that all of the different populations on their farm um could be interacting either directly or indirectly. So thank you so much for sharing that.

Cathy: 10:33

Yeah, I'm glad you could see that, Michelle, because you're right, a lot of those farms are quite diverse in what they also have on the farm. So, yeah, just to serve as a warning and a caution. So I'll go on to our second farm. Um, they had a very mixed population of bacteria identified when we cultured their bulk tank. We had some environmental pathogens and ones that came from can come from mastitis. And they all had the ones we identified, all had the ability to form biofilms as well. So some Pseudomonas, so staphs, and quagulase negative staph. And the milk inspector was able to identify a biofilm that had built up in the bulk tank, but that had resolved by the time that we kind of came for testing of the individual goats. Um, and then further bulk tank culturing left left us with carino bacteria and the mastitis pathogens still present on that subsequent culture. So, um, like Michelle said, you know, sometimes it's not just culturing once or just culturing the bulk tank. You know, we can do serial cultures of the bulk tank to see our progress as we eliminate some of the unclean issues, and then say, oh, okay, see, we still have this, and then we carry on. So this is a little bit of an example of that. So again, it came back as just the genus, not the species, so crinibacteria. And in cows, the presence of crinobacteria is often associated with what we call crinibacteria bovis, C. bovis, a bacteria, it often lives in the T canal of the udder because it likes oxygen. So it lives at that surface. And we know that if milk is not for stripped, um, it tends prior to the milkers going on, it can contaminate the milk and and you know, in really bad situations become positive on the bolt tank. So, coming from a cow background, this is what we were thinking. Um so we knew that this farm didn't have a lot of other hygiene practices, and when we visited, still didn't weren't force-stripping, post-stipping, that sort of thing. And we started with the same type of testing as the first farm we did. Back to scan and somatic cell counts on the composites to narrow down the location of the goats that were the problem, and then did back to scan somatic cell count further on those individual goats. But during sampling of the individual guys, we noticed that the udders were really not in great condition, very lumpy, a lot of supramammary lymph nodes enlarged, skin with a lot of rashes, and many halves that were atrophied. So, really a farm that had a lot of clinical and subclinical mastitis. And the producer was milking those halves that were atrophied. And so, you know, when we're doing sampling, it's important to ask the producer are those atrophied halves going in? If they are, I test them. If they're not, I don't bother with testing because it's not contributing to the bulk tank. If you're more interested in mastitis and from the goat side, I would be testing those atrophied halves specifically to know. Okay, so many goats cultured and came back PCR positive for Staph aureus, again, crini bacteria and quag negative staph. But the PCR test, again, remember it was originally formed for cows, and so it came back crini positive, but was not, didn't have C. bovis, though. So it kind of threw us for a bit. We were anticipating it was going to be C. bovis or something goat-related. And so again, we went back and did a full culture, and they identified it as crinibacterium pseudotuberculosis in the crinipositive sample. So we know it's the cause then of caseus lymphatinitis. And so it kind of threw us for a bit. It's not unusual for goats to shed this bacteria in the udders if they have Cl, but some of these goats really had enlarged supramamarine lymph nodes, and C L lesions were quite visible in other goats. And so the goats with crini in their milk also had elevated somatic cell counts, too. So it was obviously causing an issue. And again, I'm not here to draw an association between mastitis and the CL bacteria, but just to kind of advocate that this is another reason to eradicate Cl from your herd. And this is probably why they're also working towards eradicating this in Europe, and justifiably so. And so if your herd or herdino has a lot of CL, you should not be consuming the raw milk as this bacteria is potentially zoonotic and can cause infection in humans. It's more on the rare side, but I just can't tell you what the risk would be if this is in your own herd and you're consuming the raw milk, is to always just pasteurize it. So we recommended that this producer cull oligotes that have visible Cl because testing for CL is notoriously unreliable from blood tests and what have you. But since they couldn't afford to do this, at least they culled the ones with the high back to scan over 50,000. So you'll often have these farms that just have an exorbitant amount of mastitis, and so you're just gonna have to do a stepwise removal, starting with the highest and then carrying down. Um, there were also many staphorius goats, too many to remove all of them. So again, we remove the ones with the highest back to scan, pend the others together, and melt the remaining last. And so we're recommending that again the worst ones cull at least at the end of their milk cycle, and they're not to not treat them because staph aureus forms these little microabscesses in the udder, and it's impossible for antibiotics to eradicate all those bacteria. So treating those is just going to promote antibiotic-resistant bacteria to grow and pass to others in the herd. Um, what else we did with that herd was asked them to stop milking the atrophied halves of goats that had the high semantic cell and bacteran and to treat those goats with quag negative staph at dry-off with something that was shown to be sensitive to the bacteria. The farm did not force strip or teat dip after milking, so we encourage them to follow up with that. Um, and I know many producers often report that goats hate force stripping and teat dipping, but in my opinion, it's because they never got used to it when they were younger. And so, if we start doing it right from their first kidding, I think it's really important to help protect these others. And my goats are used to it, and so I'm a firm believer is they get used to it right from the beginning, it's a lot easier. So, again, just an example of a really good example of a lot of herds, so a much more common problem where subclinical mastitis had gone unrecognized for a long period of time, and to let the producer know this is not gonna clear up right away. So, this is not, you know, the other producer cleared up right away, and when we could implement those changes, this is not one that's gonna quickly turn around. For stripping them is is good for the goats, but it's also good for the owner because it's helping them to identify abnormal milk sooner and is gonna better keep them in tune with the health of the udders. I think it's really important that producers have their hands on the goat udder, not just putting milkers on, but following up with post-dip for stripping, and they just get to be more familiar with what a good udder looks like and when it's not looking so good. Swollen lymph nodes at the top of the udder and atrophy glands are bad signs, and so they should be investigated or or removed if they can't afford to be investigated. Um, most goats, as we know, don't show clinical mastitis with blood and the milk clots like cows do. Um, the milk, when they have subclinical or even mildly clinical mastitis, is slightly watery with like those micro specks of milk clots showing up. And I always tell a producer if you're unsure, fill up a little vial of milk, let it stand overnight, and it it kind of separates into a little bit of more infected milk at the top and more of a watery milk at the bottom. And it'll be more visible to see it that way. Um I just again drive home. I know producers are trying to make the most money possible, but it is not worth it to your bulk tank to get every last half in your herd in the tank. So every last half, even the atrophied ones from every goat, not to get all of those into your tank. So when in doubt, leave that half out because it's more than likely a source of bacterial contamination. So just to kind of like leave this with you, you know, from a producer and we're not recommending utter hygiene be improved to annoy you. It the these management practices work, and it's what can happen when you choose to ignore the signs and recommendations is you get subclinical mastitis. Um we encourage this producer to do quarterly SAMTEs of all goats to again, you know, benefit the goat, but also to keep driving home the message of how much mastitis they had, okay? And monthly surveying would be too much for them. You know, it would probably would have helped, but it was too much, and they were you know feeling overwhelmed as as they just had so much going on. So again, I think as Practitioners, we have to kind of tailor the testing to not be too overwhelming, but yet still be achieving its goal. So that was definitely an interesting one.

Michelle: 20:10

I think that um populations like certain producers that are looking to expand into more of a commercial type production, um, even if it's like locally selling to stores and stuff, um, that might be buying doughs from um that are just trying to get, you know, uh expand their herd, um, could definitely run into a CL problem in buying um coals from from a larger scale dairy or maybe a dairy that's just not as careful about CL. Um, and so definitely something to be aware of because I think for a long time here at least it's it's been, oh, it's not a big deal, don't worry about it. But um, I think that the mindset is very slowly turning into, hey, we don't actually know what what this is doing. Okay.

Cathy: 21:01

Yeah, I totally agree with you, Michelle. And I think it's that way for a lot of diseases that we see until they go into another realm of the animal's health, like they go from just being a lesion on their skin to now affecting udders and being in the mouth, then it's a real awakening moment. Um, you know, and it's like that with CAE and not being just affecting knees or what have you. But then once it starts to really affect the udder or kid health or what have you. Yeah.

Michelle: 21:27

Yeah. Not to be an alarmist, I'm just saying we don't actually know whether it's a problem or not.

Cathy: 21:32

So exactly.

Michelle: 21:33

I I seem to be um developing more research projects for myself and others the longer I do this podcast. So probably a good thing we're wrapping up here. It's a research creep, yeah.

Cathy: 21:45

Um, and so I'll just quickly cover our last farm just because again, it's um drives home cleanliness, I guess, from our standpoint. This um farm on Bulkank, they had a bit of coagulase negative staph. Um, so some subclinical mastate is definitely not as high as a lot of farms we had been on. Um, and definitely when we sampled some of the individual goats, they came back positive, really did not have any staph aureus, which was, I don't know, just very surprising for us. But it had been a herd that had been small for a very long period of time, didn't have a lot of goats. I think they had 70, and really hadn't brought in a lot of goats from outside. So, you know, to support your point about you know bringing in a population of goats, it can really throw off the flora sometimes and bringing in a new bug. Um, but the main flora that we cultured on the bulk tank was Pseudomonas. So, again, thinking from the environment, wet water soil, right? But a biofilm producer, hafnea and some lactococcal bacteria, which is just the hafne really kind of threw us for a loop until we did some further research. So we know Pseudomonas likes the environment and grows at cool temperatures, so um it loves to sit and grow in coolish milk and water. So we we were concerned this was a big one that if improper storage was contributing to the elevation in the back to skin because the levels were really quite high, and this person was at a threat of having their milk cut off completely from pickup. So I won't spend too much on the goats because it was really kind of boring on that end, and we focused really in the milk house on their cleaning protocols after we had originally tested the goats. And the producer hand milked and cleaned the milk equipment manually, which is totally fine because we have a lot of producers that are doing that extremely well. Um, but on an inspection of the milk tubing, there was visible biofilm. So I mentioned before it's usually not that readily able to be seen with your bare eyes, but we could feel it and actually see it as it had built up the side of the milking tubes. We swab the surfaces with our luminometer, and this is that one I said registered over 2,500, and again visibly unsettled the producer. So again, was really able to show we swabbed one couple of items that were 30, 40, 50, and then to have this one, he knew that this was definitely a concern. Um after removing the biofilm, um you know, we used a little probe that my milk inspector had. We removed it, and it was obvious the tubes had really rough surfaces and it had not been replaced recently, which the producer readily admitted that had been greater than four years. And so, but you know, that surface was just a right breeding ground for a biofilm to build up upon and kind of justifies why we recommend changing the equipment over. Um, lastly, the way the producer had hung kind of the tubing for things to be dried out, you know, you or I would think about hanging the U upside down, um, you know, with the bent at the top, and they had it so that the U was down and was collecting water. So just until you're on farm and can actually walk through it with someone, it's just fascinating what you can pick up. So I had an uncle in public health, and he always said, Boots on the ground, boots on the ground, or you won't figure anything out. Um, so the water was sitting in that downward hanging position and growing pseudomonas is what it was doing. Um, so again, dry, dry, dry. You know, it's the same with these automated milk feeding systems for kids that have a lot of tubing that's very prone to biofilm buildup. I have producers have two sets. So they switch them out every day, they rinse them out, and they hang them upside down because they have to have a period where they're completely dry so those biofilms don't get going. So, as an aside, so that was the pseudomonas issue. The lactococcus and hafnea were really interesting because I mentioned to you earlier some of these ones are kind of normally present in milk, but you normally don't grow them on the bulk hang. So it was unusual for us to see that. And I mentioned they're kind of in the you know, part of growing or manufacturing yogurt and cheese. So the presence of these bacteria indicated the tubes were with these biofilms were in effect growing cheesy yogurt on their own. So we higher up were able to screw scrape some of this material and we flushed rinse water through and kind of cultured these bacteria from the tubing itself. So driving home the importance that we need to eliminate cracks and rough surfaces and protein buildup because they reduce the smoothness of all these surfaces. So, again, you know, the flashlight really came in handy on that one. Close your eyes, run your hand through some of these containers. Um, and I often tell producers at least once a week go through your system and just kind of walk through the whole thing with your own flashlight or your fingers, just kind of paying special attention to anything that feels slimy or slippery. And again, really needs manual cleaning to get them down. No detergent can really get at them. So, in summary, I appreciate Michelle letting me, you know, share these with you because I learned a lot from them, so I hopefully you can as well. They're interesting cases, good examples of where we're vulnerable, and kind of walk you through the stepwise process we use to kind of troubleshoot some of the problems. Um, if you're in a good place with milk quality and want to stay there, you know, I would have the producer perform quarterly cultures of the belt tank so you get to know their flora in each season and do a California mastitis test on every goat quarterly, even you know, in these good herds. And each month I would do a CMT on composite samples to quickly identify potential hotspots. So there's a way you can tailor this for each farm, you know, as to how much or how little they do at different times of the year. Um, would really stress though not to milk atrophied halves. Cull your CLs and Staph aureus goats as soon as possible. And I think as an industry we've really been lulled into a false sense of security. We don't have mastitis issue because it's not really visible. But I can say that every single farm we've been on has it, and that we're just not looking hard enough if people are saying they don't have it. Okay, that every person that has a goat herd would know that they have subclinical mastitis. Um, once we have new tools, I think to diagnose problems, it's an opportunity for us to relook at things to see if maybe we've been missing things. And this test that I've been working at that I hope becomes more commercial with the PCR array has really kind of opened our eyes to that we're missing some pathogens that are unique to goats. So I think there's you don't have to have access to the array, but kind of pursuing more in-depth cultures with your local lab to kind of probe further. Was that a crini or was it CL? Is it, you know, what strep actually was that? What don't just be satisfied with quag negative staff, ask them if they can speciate it up for you. Um, I think the hard part why we've had so little success in troubleshooting is, you know, for example, we asked a producer to call 30 goats and their numbers don't go down, is kind of related to some of these goat-specific diagnostic tools that we're struggling with. Um, because they're made for cows and we don't currently have anything that's entirely goat-specific. Our lab is uh adapting as we kind of raise these other pathogens that we're picking up, but I definitely think there's a long way to go. So, and obviously more research needed. So, again, importance of a stepwise plan, um, you know, one intervention to help get out of the pelming range, another intervention, as you know, then we when we can next afford it, and just keep going stepwise so we can keep the producer feeling successful, that we have success with one intervention makes them more willing to take on the second one. But just to recognize that some of our suggestions are non-negotiable. Um, diagnostics and preventive practices don't have to be expensive, um, but milk quality does require effort and awareness, I guess, on behalf of the producer is what I would say. So, overall, Michelle, I hope this helps. I never claim to know everything about milk quality, but I'm a student of of the of the field and hope to keep learning more every day that we go out.

Michelle: 30:23

Well, Dr. Brahman, I want to say thank you so much for sharing your insights in our original podcast. And then these case studies, I think, are just gonna be invaluable for folks like me who are you know really care and passionate but just don't quite know how to get started. Um, and so uh this has been incredibly insightful, and um, I think some very, very uh important um universal messages that we're gonna encounter similar cases or similar scenarios on a lot of these farms with you know their own individual twists. And so um I think these will be great for getting the wheels turning for folks. So thank you so much for taking the time to to prep for this and sit down and chat with us. Um I apologize in advance if your email inbox blows up with requests for help working up uh goat milk quality cases, but um really appreciate your insights and your time. So thank you so much.

Cathy: 31:24

Thank you.