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Foreign. Well, in true form, we have an episode today that stems from a real world clinical conundrum, a real world clinical question that one of the other attendings asked in our group chat regarding GBS culture and its result. Now, at first, first take, I know what you're thinking. Wait, what? I mean, group B, strep culture. What about it? I mean, if it's negative, it's negative. If it's positive, then she gets intrapartum prophylaxis to prevent early onset neonatal sepsis. All of that is correct. Totally true. But the question is actually something that kind of came from left field, but is totally applicable because this, once again was in a current patient and it's nowhere in the guidelines. So this potentially, potentially is a gap in the care consensus. So again, I'm not saying we know what to do here once we review this episode, but I am going to give some real world clinical applications and things to consider should you have a patient like this. Okay, because I'm going to give you the question in a minute. But the answer is. Oh, it's pretty darn clear. It's pretty darn evident from the guidelines, comma, and it's not. So those are both of the answers. Well, we know what to do ish. And we actually don't know what to do. So let me explain the question here. So one of the other attendings sent a message in our attending group chat to the faculty channel and said, hey, I've actually not seen this before. And is this valid or not? So here's the situation. Routine OB patient had her routine GBS swab in the correct time. Remember, the current consensus and the universal collection of GBS is between 36 weeks and 37 weeks and 6 days. Or just call it what you want. 38 weeks. It's a two week span where we do universal GBS, vaginal and rectal swab. That goes without saying. Everybody gets that. Unless of course, the patient has a GBS bacteria or a previous child who was affected with early onset neonatal sepsis, for which they are called forever carriers. Okay, so routine screen. Got it. Fine. It was negative. Cool. No problem. Right? That's pretty clear. But here's a catch. The patient was actually on oral penicillin for pharyngitis. Right. For a strep throat. I think it was actually amoxicillin. The point is, it was a penicillin based therapy. So our co attending, one of my partners, put this question out. It's a good question. Hey, is that GBS culture result valid? I Mean it came out negative, but the patient was on oral penicillin. Can that actually lower the count temporarily where we get an automatic kind of a false negative result? I don't know. That's a good question. That is a good question. And the reason it's a good question is because it's not that straightforward. We, we totally, totally have guidance on what to do with this. We definitely do. From ACOG, of course, for universal screening for GBS. That goes back to ACOG's Committee Opinion 797 back in February of 2020, but it was reaffirmed this year earlier, 2025. So we get that it just says screen for GBS 36 to 37 and 6 outside of that criteria that we talked about a little while ago and it says nothing, nothing about a patient on penicillin based antibiotics. All right, so what do you do? This is a real world issue. I mean, it happened to our co attending. It's a good question because penicillin obviously is very effective at dropping bacterial counts of GBS in the vagina. So could it be, could it be that, that could lead to a false negative? Now, right now. So let me give you the yes and the no. The no is there's no guidance anywhere that says that we should not screen for GBS if the patient is on some kind of penicillin. However, if you think, well, that's pretty clear, then I guess we're done. That's the answer. It really doesn't seem to matter. Wrong, sir. Wrong. You get nothing. You lose. Good day, sir. Yep. The truth is it can be possibly a little bit more complicated because there is a case report, although it is a case report, that's an n of 1, where this exact same thing happened and the patient was later found to convert from a negative GBS culture to a positive GBS culture after her antibiotics were taken. What now? So now please don't get upset with me. I'm not suggesting, of course, that we change all of our guidance based on a case report of one and not saying that, but it's something to consider. And this was. We went back and forth in our group chat and so my first stock answer, of course by guideline is, guys, it doesn't matter. There's no specific clause which says we shouldn't collect this at this time because a negative culture is a negative culture. That's valid for up to five weeks. But as the chat started evolving, going, but wait a minute, what if we actually do suppress that and then off suppression, she actually is a carrier and we miss it. So of course I went back and did, you know, a little bit of research and sure enough, I did find that case report, all of which we're going to cover in this episode. Now, there is a caveat. Guys, hold on. The reason we're going to. You want to come back after the intro, which we're still in, is because there's more to that case report than meets the eye. Okay? Because there can be potentially, potentially a difference between responsive GBS bacterial count from IV antibiotic therapy versus oral antibiotic therapy. So once again, if you think, wait, this is easy. This is such a weird topic. It's not a big deal. We screen everybody for GBs regardless of antibiotics, 36 to 37 in six. And so it shouldn't make a difference. That can be correct. However, Wrong, sir. Wrong. You get nothing. You lose. Good day, sir. Yes, that's all my point. It's all my point is something to consider. Make this a part of your OB journal club. Talk with your fellows about this. Is should you have on that weird chance and coincidence that the patient is about to get GBS swab and she's on a penicillin based antibiotic and it's a good question to ask. Is that test going to be valid or are we artificially suppressing the count and then potentially risking not treating a GBS carrier? It's a good one. It's a good one. We don't have a good answer for it because that potentially, potentially is a gap in the guidelines. I found this interesting. So I gathered some data. This is where we're going. Can oral penicillin affect or impact GBS culture results and lead to a false negative? Think about it. We never thought about this before. I'm like, we just collect it. But maybe, maybe just something to consider. We're going to cover both sides of this. Even though we have an n of 1. An n of 1 as a case report doesn't mean it has happened before because people have to write it in and write it up and get it submitted for peer review. So you move the needle. So maybe it's happened more than one, but people don't write it up. So it's something interesting to consider. We're going to do both sides here. As we are. If we are in court, we're going to do the side that says it absolutely doesn't matter. Who cares? It's a negative culture. Her chance of being colonized to a significant level within the next five weeks, which is what the guidance says is extremely low. So once you're negative, you're done. And then the rebuttal, which is an N of 1. One case report, but all it takes is one bad case of early onset neonatal sepsis to change the picture on that. And that child was actually infected and affected by otherwise undetected GBS because of the patient's concurrent penicillin therapy. Fascinating. At the end of this, we're going to give some practical implications based on what we know and what we don't know from this real world clinical situation. It's actually a really good case. I think I've set it up enough. Let's be done with the intro and we'll be right back. This is Dr. Chapa's own OBGYN no Spin podcast. Well, we're taking this question, can oral penicillin based therapy affect a vaginal rectal GBS culture? Result. We're gonna take this to our pseudo podcast courtroom and present both sides of the case as each litigant and defendant give their account of the facts. So here we go. Oh, there it is. This is our court song, I guess. Oh, I like Law and Order. Not a sponsor. Isn't that just a great song? I mean, it's awesome. I mean, really, that. That's got some jam to it. So we're taking this question to our pseudo podcast court to figure out if oral penicillin therapy is guilty of lowering vaginal GBS culture results. Let's. Oh, my goodness. Okay, let's get out of that. Because if not, I can listen to. I can listen to Natural Wild. I think that's got some. Man, that's got some good vibe to it. So right when you first listen to this question, like, ah, is that a big deal? I mean, is this. Is this a thing? Well, we didn't think it was a thing until it happened to us. And I'll tell you what we decided to do in this case. But the truth is, as we get back to the facts and get away from the silliness, there is a true gap here in the guidance. So let's start with the. No, it absolutely doesn't matter. Who cares if she's on oral penicillin, a negative swab. You've done your diligence there, which is you're looking for colonization. And whether it's natural absence or suppressed absence, it's negative. Negative is negative. The one time. The one time where repeating. The GBS culture is mentioned in Committee Opinion 797, which, although it originally came out years ago, it was reaffirmed in 20, 25. There's only one time, and that's based on length of time of remaining pregnant after first collection. Okay? So if you ask on an oral board, what's the one criteria of when you want to repeat a GBS in the same patient in the same pregnancy? And it's very simple. Two things have to be met. Number one, she was negative on the initial screen. Number two, she's still pregnant five weeks later. Because the validity of a positive screen goes down with time. Because after about five weeks, it is possible for the patient to have new acquisition of GBS colonization and to reach a certain level, which is, of course, potentially dangerous for the child. So it's five weeks. All right, so let me read this to you. So the only criteria is initially it was negative at first, and the patient remains pregnant five weeks later. That's it. There's nothing about rescreening. If the first collection was negative and the patient was on antibiotics, there's nothing in there about that. So right now, according to the guidance, it says if the patient remains pregnant five or more weeks after a negative baseline GBS test, then GBS screening should be repeated if a recurrent episode of preterm labor occurs or. Or at 36 to 37 and six weeks of gestation, which is your routine time to screen, end quote. So that's it. That's the only time to rescreen. If they're positive, they're just positive. Or if they've got GBS bacteria, they got GBS bacteruria. And the only time, the only time that rescreening is mentioned in that co. The committee opinion is based on length of time of negativity since its first collection. That's. It has nothing to do, says nothing about whether the patient's on oral antibiotics or not. So. So remember what we're doing here, guys. We're trying to present this as if in a court making both sides. And right now we're presenting the side that says it doesn't matter. A negative culture is in fact a negative culture. You've done what you're supposed to do, move on, you're good for five weeks, case closed. We looked for it, and it's not there. Five weeks. However. However, remember, we're trying to give both sides of the argument here. And there is that case report. I get it, I get it. It's just a case report. It's an n of 1, but potentially there's more, but people don't write it up. And it's just something to consider. I'm just. I'M bringing this up as a potential gap in the guidance when you figure if GBS is so sensitive to penicillin, can taking oral antibiotics temporarily. And that's the catch. Temporarily lower the count where it's not detected by. And then the patient actually can convert quicker? I don't know. We don't. So to be very clear on this side of the court, on the defense side, which is, hey, our test is innocent here. The oral antibiotics here have nothing to do with this. Keep going. That is how we've just presented. When we come back from our break, we're going to cover the next part, which is the case report of N of 1. I get it. But it does open up the eyes that maybe it is potentially something that we should pay attention to. So we'll take a quick break and we come back, we're going to talk about the other side that says that oral antibiotics can be guilty of causing a false negative. Something to consider. We'll be right back. You're listening to the ob GYN no spin podcast. Can I take your order? Can I get a tall chai, a large black coffee?
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A what?
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Large black coffee.
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Do you mean a venti?
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No, I mean a large. He means a venti. Yeah, the biggest one you got. Venti is large. No, Venti is 20.
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Danny.
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Yeah, large is large. In fact, tall is large. And grande is Spanish for large. Venti is the only one that doesn't mean large. It's also the only one that's Italian. So now you can skip all of the coffee shop etiquette or pseudo etiquette and make your great tasting coffee at home. We're thankful for our partnership with the strong coffee company that is striving to reach our natural greatness, which is not your ordinary cup of coffee. It has adaptogens, collagen and nootropics to help you reach your maximum potential without the caffeine crash. So thank you to the strong coffee company for your partnership. 20% discount with the link only in our show notes that is 20% off whatever you buy online so that you can make your own grande Venti large at home. Thank you for the strong coffee company for your partnership.
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N rakuten.com and we are back from that mini recess. Order. Order in the court. I just had to do that. I just like that. Should we do that again? Sounds like a woodpecker. Order. Order in the court. All right, so anyway, so let's get into this because if you think intuitively, well, penicillin taken by mouth or antepartum, you would think would be able to reduce bacterial counts in the vagina. So it doesn't make sense. Why isn't that in the committee opinion where potentially it would lead to a false negative? Well, so before I get into the other side, the other part of the courtroom which says, yes, potentially it can, there is something slightly suggestive of. Of this in that co, in that committee opinion. So let me just say this right here. It does not list oral penicillin as a contraindication for swab collection, but it does say this. Quote, Neither antepartum nor intraparum oral or intramuscular regimens have been shown to be comparatively effective in reducing GBS early onset disease, end quote. Did you all get that? Neither antepartum nor intrapartum oral or IM regimens have been shown to be comparatively effective in reducing GBS early onset disease, end quote. In other words, the reason we do IV therapy is because that's the way that we reduce colony counts. The others are not effective, meaning if they're not effective, then they don't reduce a colony count. Y' all get that? So it indirectly addresses this in the co. This is a big deal, guys. So. So that's the one part where antepartum oral therapy is mentioned, not as a contraindication. But do you see that? So here's the reason why, at least in theory, why oral antibiotics, even though it makes sense that they could potentially reduce bacterial colony counts, why they're not listed as a contraindication is because, quote neither antepartum nor intrapartum oral or intramuscular regimens have been shown to be comparatively effective in reducing GBS early onset disease. End Quote, so that is the reason. That is the reason. So if you're asked why, why is it not considered a contraindication? Because oral therapy possibly, possibly is not the same to reduce the counts as iv. Now we've known this and we know that IV antibiotics very quickly, within hours. Remember, adequate GBS prophylaxis for a neonate is antibiotics administered within four hours of birth. Okay, We've covered this many times before. It's not number of doses given. It has to do with the last dose being within four hours of birth to maintain a steady state of antibiotics in the child. IV antibiotics is so effective to drop count in the vagina and to give a level into the child that that's considered adequate prophylaxis. Very effective. Within hours those counts drop. But oral may not do that. According to the co, neither antepartum nor intrapartum oral or IM regimens have been shown to be comparable in its effectiveness in reduc early onset GBS disease. End quote. With the implication being that oral therapy is not going to drop the counts. It's not going to drop the counts. So having said that, oh boy, all you need is one. One case. And there is a case. Now, even though this is a case report, this was published by Kim et al and the title was Neonatal group re Strep sepsis. So let's stop there. It wasn't like it was just colonized. I mean this kid has had neonatal GBS sepsis. It's true. Infection quote after negative screen in a patient taking oral antibiotics. End quote. And this was in Obstetrics and gynecology, The Green Journal, 20 years ago in 2005. So the title was once again Neonatal group B Strep sepsis after negative screen in a patient taking oral antibiotics. In The Green Journal 2005. This was a 20 year old. She was on oral antibiotics at 35 weeks for a recurrent UTI. Her GBS screen was done, it showed negative. Therefore she didn't get IV antibiotics because she didn't. Now remember, this was notice at 35 weeks. Why? Because that's when we used to collect it. We actually used to start collecting GBS at 34. Then we walked it down a week to 35. Now we walked it down a week again. So now we start at 36, pushing it to 37 and 6. All right, but it started initially with 34 weeks. When I trained, you started collection at 34 to 36. Then it went to 35 to 37. Now of course we're at 36 to 37 and 6. Short of it is this patient ended up getting an induction for mild preeclampsia or preeclampsia without severe features and the infant developed early onset neonatal GBS and pneumonia and sepsis. Wow. Now I get this. Guys, please don't send me a message. It's an n of 1. I am not arguing for change in committee opinion guidance based on the n of 1. My point is something to consider because, wow, we went back and forth on this in our faculty chat like this is something we should talk about. And now again at the end, which we're about to get here, I'm going to give you some real world implications here. Even though the guidance says what it is, you collect it. Unless there's those pre existing issues, GBS in the urine, previous child defector, where she's a forever carrier, then you screen universally at 36 or 37 and 6. Why? Because oral antepartum therapy has not been shown to reduce early onset GBS infection in the child. Meaning it's not enough to drop counts. So there's nowhere in there that says unless the patient was on oral penicillin or penicillin based therapy. Okay, but according to this case report, as the authors state, quote, relying solely on a negative culture in the context of recent antibiotic use may not be appropriate for intrapartum management. That is from the end of one and it's just interesting, that's all, is that it is possible that if we suppress the level down, we are missing a potential carrier state. So very easy. Guys, what does this mean? What is the real world implication here? Number one, guidelines exist and they're just guidelines. They're not de facto dictums. Okay? They're not mandates. It's just, hey, something to consider because it's. You also have to have a lot of things coincide and collide at the same time. A patient who's on oral antibiotics for say pharyngitis, or maybe it is for uti, ASB suppression, whatever this becomes an issue and the guidance right now does not make an excuse for that. There's no caveat for that. And a negative culture is supposed to be a negative culture. The real world implication is if this happens to you, potentially knowing that there's even though it's a small chance of being false negative, it's not zero. Have the patients drop antibiotics. But here's the follow up dilemma to that. How long do you stop it? How fast can she recolonize? Do you stop it for five days? Do you stop it for seven. Do you stop it for two weeks? In other words, should you stop it at 34 weeks and then screen? Nobody knows because there's a gap in the guideline. So I'm a little conflicted by this. What we came up with is, well, the patient finished her antibiotics. Let's just screen it again a week later because now she's going to be like 37 weeks just to see what that did. Because we don't want to miss something if it's positive. Wow, we caught one. Although the chance of that's supposed to be very small. And I told our CO attending Dr. Neal, I'm like, hey, we'll write that up. That's a good medical education point. That may be something to consider. And It'd be an N of 2 in the literature. All right, so the real world implication is if the patient is on penicillin therapy and you're getting closer to a gbs, you can consider stopping it before. How much before? I don't know. Because we don't have that guidance. It seems reasonable to stop, you know, one week max, two weeks, because she's also on suppression for a reason or on therapy for a reason. And if you can't do that, then just wait for her to finish and then collect it when she's done. But we don't know what that interval is. Or you can just believe the data, which, hey, I'm a fan of the data. That a negative culture is a negative culture and is supposed to be predictive for five weeks isn't that interesting. So it kind of is a little conundrum and not as clear as you would first think. So I found this interesting. We don't have a real, you know, clear cut answer here, but that's what makes it fascinating. This is something that's worth discussing, which is why we're doing this. Because sometimes it's not all a guideline and clear science. Sometimes that's where the art of medicine comes in and you have to take something to court and see what the best evidence is. And in this case, the best evidence is that seems to be negative. It's supposed to be valid for five weeks. But if you want to be ultra conservative and make sure that we're not, you know, artificially lowering it and putting a child at risk, re screen her later. Now remember, culture is still considered the gold standard. PCR and its in that committee opinion, is acceptable as a point of care test for those patients at term, for those patients at term who do not have a previous culture done. But culture remains the gold standard, mainly because of the ability to do sensitivity testing. But just something else to consider. Maybe you get a pcr. We settled for a culture because it is a traditional first line and still the preferred. And so that's what we're going to do. Talk amongst yourselves. Take it to your journal club. Fascinating topic. Even though the community opinion states that antepartum or intrapartum, oral or IM regimens are not comparable in their effectiveness to reduce GBS early onset neonatal disease, meaning they should not have the capability to reduce counts. Negative culture should be a negative culture. Negative culture should be a negative culture. Until it isn't Podcast family, as always, we're thankful for you. We're glad you're part of our podcast community. Thanks for pulling putting up with our silliness. Even though we always are data driven, we always can have a little bit of fun with it. That's my jam. Come on, Michael, leave it on there. He said hurry up. Wrap it up. All right, so let me wrap it up. Podcast family, we'll see you on the next episode of the no Spin Podcast. Now that we've done all that, let's take it home. Podcast family, we're thankful for all the support that you've given us throughout the years. This has been the Ob GYN no Spin Podcast. We'll see you on the next episode. SA.