126. Capnocytophaga

It's the best pun Cal's ever done, and I don't say that lightly, son. Here's an episode on Capnocytophagia! 

Transcript

jame_1_03-24-2025_095802: 0:18

Callum? How you doing?

callum-_1_03-24-2025_095747: 0:20

I am I'm pretty good. I was just reflecting on a recent holiday I took to Cambodia. When I went to the Anchor wa, but I was wearing this hat and it had quite a long bit, the frontals, what those hats called, the bit that come to the front.

jame_1_03-24-2025_095802: 0:33

They're called caps.

callum-_1_03-24-2025_095747: 0:35

Yeah, and it was a bit long and it was low on my face and at the time I felt this hat is too low because of this cap. We've got no sight of Asia cap, no sight of Asia

jame_1_03-24-2025_095802: 0:48

God, that's so much better than I thought it was gonna be. Oh, and what a coincidence that is Callum'cause of, what are we discussing today?

callum-_1_03-24-2025_095747: 0:56

cap, no sight of Asia.

jame_1_03-24-2025_095802: 0:58

Indeed. Not a lot of information about this, bug. I have to say less than I thought it was going to be. This is sort of a follow up, a two-parter from our Pastor Ella episodes. So this is our bite pathogens phase of the show. but I had a lot of difficulty researching this.

callum-_1_03-24-2025_095747: 1:12

Yeah. I think it's an organism that we talk about in the context of animal in particularly quite a lot. But yeah, I, I would agree that. The literature expect there to be more. We're not angry, we're just disappointed.

jame_1_03-24-2025_095802: 1:25

Hmm. Why don't you tell us a little bit about Kacy phage Genus? I.

callum-_1_03-24-2025_095747: 1:30

Yeah. So, the, this organism was first recovered in 1961 in a blood culture sample from a sort of adolescent that was bitten by a dog in America. Yeah. So it was first recovered in 1961 in America, from a

1:43

PLE Optimiz.

callum-_1_03-24-2025_095747: 1:44

17-year-old boy who had been bitten by a dog. It wasn't given the name, it currently cares until 1989, at which point it was called cap, which essentially means requires CO2 to grow carbon dioxide. So like capnography that we use in Inized patients.

jame_1_03-24-2025_095802: 2:01

you don't need to explain capnography to doctor population.

callum-_1_03-24-2025_095747: 2:04

Yeah. But there's lots of lot of doctors listening and they

jame_1_03-24-2025_095802: 2:06

I'm sure they understand also

callum-_1_03-24-2025_095747: 2:08

I'm not editing it out

jame_1_03-24-2025_095802: 2:09

Fine.

callum-_1_03-24-2025_095747: 2:10

cyto, phia. So it's for its ability to glide. It's got gliding mobility in culture, so that's when it's first picked up. And, and essentially that case tells you pretty much everything you need to know about this organism. That it's higher risk in people have had splenectomies and you find in blood cultures. So yeah, it's a normal part of animal's mouth. These are sort of, sort of mouth organisms. There are kacy, aphasia other species of the genus in, humans. And you also find it in the mouse of cats and dogs. So people have tried to look at that. I think in 1974 there was a study where they looked and tried to find it in the mouth of dogs.

jame_1_03-24-2025_095802: 2:50

Well I've got some info on that actually. Carl. So yeah, so they're, they're a normal part of the mammalian oropharynx and they are, are from the family Flavour. A CI, would you like to know the other members of Flavour? A CI?

callum-_1_03-24-2025_095747: 3:05

Yes.

jame_1_03-24-2025_095802: 3:06

Well, you can't because Kaci age is literally the only ones whose genus I recognized all the others are small print.

callum-_1_03-24-2025_095747: 3:13

Right.

jame_1_03-24-2025_095802: 3:13

but the genus is divided into human oral species and zno associated species. And so now callam, it's time for a good old fashioned Jay McCallum. Alternately, read the names. Let's start with the human orals. These are commonly causing trouble in the immunocompromised population. Gingivalis,

callum-_1_03-24-2025_095747: 3:33

Granulosa

jame_1_03-24-2025_095802: 3:33

hemolytic,

callum-_1_03-24-2025_095747: 3:35

Lead Better eye.

jame_1_03-24-2025_095802: 3:39

ciaa and then the zoonoses associated ones. So these are the ones that live in, cat and dog mouths canis. Mm. And again, they're, they're sort of risk factors in asplenic patients, but also cirrhotic patients. So that that kind of immuno compromise is a problem there. And so, out of those, probably the only that I've remember encountering would be Canam, SSUS, and maybe Canis, and maybe.

callum-_1_03-24-2025_095747: 4:08

I've seen gingivalis on samples, but it is usually, you know, you say you've got tissue from a patient that's undergone ENT surgery or maxillofacial surgery and working up all the organisms and you find

jame_1_03-24-2025_095802: 4:21

Yeah.

callum-_1_03-24-2025_095747: 4:21

all the ID and, and then you think math don't really care about that'cause it's not, it is part of the normal oral microbiome.

jame_1_03-24-2025_095802: 4:26

Well, yeah, and, and actually acau of agent of periodontal disease as standard. So when you're getting dental cies human kacy, phia species are at least partially to blame,

callum-_1_03-24-2025_095747: 4:38

Hmm.

jame_1_03-24-2025_095802: 4:38

There. Yeah. Okay. Then let's talk a little bit about the clinical, picture here there's not a huge amount to say here, so I'll, I'll just run through it and then you can take the micro cal.

callum-_1_03-24-2025_095747: 4:47

Yeah.

jame_1_03-24-2025_095802: 4:47

So as we said, they're normal commensals of the, of the mammalian oropharynx. So because of contact reasons human cat and dog bites are going to be the main sources of infection. And the risk factors for invasive disease, which is when we really would worry about them would be immunocompromise such as splenectomy and cirrhosis as we've talked about before, alcoholism having cancer or being on chemotherapy but then other milder causes of immunocompromised such as chronic lung disease, diabetes, and being corticosteroids as well. In terms of pathogenic mechanisms, there's not a lot to say here. They, they possess both catalase and oxidase at some of the species and LPS and in terms of what they can cause. They, they are causing periodontal disease as standard. But they can be implemented in polymicrobial, animal bite infections and cellulitis. And if they become invasive, like in those immunocompromised populations that we've just mentioned, they can cause septic shock and they can spread to places like the brain. And cause meningitis, rarely cerebritis, they've been reported in some joint infections. But really it's, that's not very common uh, to.

callum-_1_03-24-2025_095747: 6:09

Yeah, generally speaking, you're suspecting this when someone's had a bite. The patient's more unwell and they've had blood cultures, and if you're going to isolate it, you won't, you won't expect to isolate like so Pastor Ella that we talked about before. You tend to find in those tissue samples or swabs or something like that, and it causes quite a severe localized infection, particularly in around your hand or wherever the bite was. I. Ophia is less, significant pathogen in that local infection. But you tend to see it in blood cultures isolated. And these patients can be incredibly unwell. They can have peripheral necrosis, gangrene they can also lead to meningitis. So the cases that we've had locally, not many, but when you've seen it, it's generally been causing us some sort of. Disease. It may just be that that's the context, we're only picking it up at the more severe end of the spectrum because, if you can only isolate in the blood cultures, you're only see any blood cultures when the patient's more significantly unwell. So there might be a sort of I guess, selection bias going on there. But certainly something to think about if you've got a very sick patient that's had a bite, particularly if they had a splenectomy

jame_1_03-24-2025_095802: 7:14

Alright. Tell us about the microbiology Cal.

callum-_1_03-24-2025_095747: 7:17

So it's gram-negative. And it's basil. It's a rod. It's got pointed ends like a canoe. It might, you might mix it up with legionella as one of the possible, things in the lab. It's facultatively anaerobic, so it can grow in both presence of oxygen, but also the absence and it's slow, slow growing. So I guess we're thinking about if you've got clinical suspicion, incubate your blood cultures for a bit longer, incubate those plates for a bit longer. It should grow in a normal blood egg or Columbia blood egg are, particularly if you're incubating that in CO2, which is often done it will not grow in McConkey. And in terms of the how it grows on the plate. So as always, we're linking to Microbe Canvas, which is a great website,

jame_1_03-24-2025_095802: 7:59

Hmm.

callum-_1_03-24-2025_095747: 7:59

which has some more details on it. Essentially. It's fairly small organism at 24 hours. If you give it a bit longer, there'll be shiny, smooth, spreading edges, no homolysis. They can be kind of pink, purple color but they're generally yellow when you're not on the blood agar, and they should glide. They've got gliding motility. So the, the edge spurs as a fringe when you try and push it. So lots of nice pictures on microbe canvas. And then as we talked about earlier on, so cap cyto can amorphous and the other is zoonotic ones will be positive on your catalyze and oxidase test, whereas the human species are negative in both of those. It's quite different really.

jame_1_03-24-2025_095802: 8:41

Hmm.

callum-_1_03-24-2025_095747: 8:41

So that's a good way to differentiate them. I guess you're seeing more animal bites, but in human bites may be captain by the, those human organisms are know, more of a concern.

jame_1_03-24-2025_095802: 8:50

Yeah.

callum-_1_03-24-2025_095747: 8:51

you idea it? So you do mold it off? That's

jame_1_03-24-2025_095802: 8:53

Hmm.

callum-_1_03-24-2025_095747: 8:53

how you would idea, I think. you can do sort of biochemical tests and sugars and so on, but I don't think you're gonna be asked that. So not gonna, not gonna develop that.

jame_1_03-24-2025_095802: 9:01

Yeah.

callum-_1_03-24-2025_095747: 9:02

look at it for other certain molecular techniques as well. You might pick it up in a 16 SBCR for example.

jame_1_03-24-2025_095802: 9:07

When it comes to treating it I was surprised to see that there's no. Ucast or CLSI breakpoints for this organism? They've not been presented or validated yet, but I, I know that we do do antibiotic testing for it. I suppose that will vary by by a lab. But there's been a couple of review articles on the treatment for cap cyt aphasia recently. So we've referred in the prep notes to them. It will normally be sensitive to Bela beta-lactamase inhibitors, combinations, carbapenem, and for very serious infection. The CDC recommends using one of those but it's also sensitive to chloramphenicol, tetracycline macrolides but not variably, erythromycin And it is variable as in, it's been reported in some studies, but debated in others to Amano Glycoside, the other beta-lactams including Atri metronidazole, quinolones, Rifampicin and Vancomycin. And it is. Invariably resistant, Tocin, fu acid, polys, and trimethoprim.

callum-_1_03-24-2025_095747: 10:13

Yeah, I, I guess when we use, know most of the empiric treatment that we've got for. Cat Dog bites is ocla and often patients are given that even if there's no signs of infection with a cat bite.'cause the risk of, significant infection is so high.

jame_1_03-24-2025_095802: 10:27

hmm.

callum-_1_03-24-2025_095747: 10:27

and I always understood that the rationale for that was the sort of rate of beales production. And these organisms is

jame_1_03-24-2025_095802: 10:34

Yeah, in, in past and, and Kacy Phia. So Kacy Phia does sometimes produce benes. So there's been reports of the resistance, particularly from the human species. So that's interesting. That sort of implies that it's. beta lifetime use in humans and not animals that is contributing to that. Whereas with pastor, I think last time we said the opposite. Yeah. So actually, the CDC has a good page on this, which also mentioned that if this thing is sensitive to penicillin, you should probably just use that. So if you have the option. Then please do. But if you don't then com socl is, is usually your go-to. And as, as luck would have it, it's the go-to for, human bites as sort of standard. But I suppose it is good to know that in your penicillin allergic patients that tetracyclines like doxy should work and macrolides that are in common use such as clarithromycin and azithromycin elsewhere would also work as well. And yeah. So for normal sensitivities, it's susceptible to chloramphenicol clindamycin. Tetracycline macrolides, but not erythromycin ipen and beal latam beta-lactamase inhibitor combinations.

callum-_1_03-24-2025_095747: 11:46

So, you know, I guess we've literally just done a mini series on antimicrobial susceptibility testing what to do when there are break points, what to do when there not break points. And this organism would fall into the latter.

jame_1_03-24-2025_095802: 11:58

Hmm.

callum-_1_03-24-2025_095747: 11:59

you know, I guess what you cast guidance documents say to do is, you know, you look at, you find this organism, you look, is there break points? Nope. Okay. So you looked at the literature. So that's what we've just done for you. We've got the references there that James put together, you have isolated it, then the next step would be to go and determine an MIC to these different agents. And then use that to guide your therapy using the when There are no break points document on the UCAS website. So I expect your patient's probably gonna be on CO with Clave or Piptaz or carbapenem if they're very unwell. And then you'll test these and you may be able to set'em down to something like oral doxycycline, but I don't think I would start with that treatment. It would be, you know, relying on that beta beta-lactamase inhibitor or carbapenem CDC tells us to do. Until you get that MIC data and see if it's below the sort of level, which you can say is likely to be devoid of resistance mechanism or a conservative approach, which suggests that the treatment is likely to be successful which isn't quite susceptible, which is, kind of bit more of a mouthful, isn't it? It's easier to say it's s but only, if it were so simple.

jame_1_03-24-2025_095802: 13:06

God, it's not even in the MIC database for ucast. I was just.

callum-_1_03-24-2025_095747: 13:09

I already checked that, which is why I'm reluctant to say

jame_1_03-24-2025_095802: 13:12

Fine. Okay. And that's all we had for today. They don't all have to be big multi-hour discussions. Do they Cal

callum-_1_03-24-2025_095747: 13:19

they do not. But hopefully we'll get some more data on this at some point. But at the moment, that's all you got. I.

jame_1_03-24-2025_095802: 13:25

Cap? No. Site ofia absolute classic.