1/ #medtweetorial on bacteremia real or not real?
A 70yM comes in with SBO and tachycardia and leukocytosis. Blood cultures are sent on admission. 1 out of 2 comes back with Clostridium spp (not perfrigens/ septicum). To treat or not to treat?
2/While true bacteremia needs to be aggressively treated, there is also a high rate of contamination. Figuring out which blood cultures represent true infection can be tricky.
3/ What is the contamination rate of blood cultures?
What is the chance a positive blood culture represents bacteremia?
There is a .6-12.5% contamination rate of blood cultures.
4/ However, when it comes to + blood cultures, 20-50% of + blood cultures are contaminants. There number vary widely from institution to institution based on how the cultures are obtained.
ncbi.nlm.nih.gov/pmc/articles/P…
5/ This is why it is important to consider the pre-test probability of bacteremia before obtaining cultures (see thread ).
6/ When thinking about contaminants, most are gram + organisms on the skin. Most gram – bacteremia are true infections. However, even an unlikely pathogen like S. epi, is likely true bacteremia if it grows in 2/2 cultures drawn correctly at 2 different venipuncture sites
7/ less than 1/1000 prob that this would occur by chance). Also, consider if the patient has a source for infection such as a medical device.
psnet.ahrq.gov/web-mm/contami…
8/ When the cultures come back with 1 out of 2 + for a gram + organism, it is trickier. S. aureus should always be treated as true bacteremia (87%/93% true infection).
9/ Other GP should be treated as true infection (w % true infection) include Enterococcus (63%/70%), S. pneumoniae (100%100%), B hemolytic strep (97%/67%), Clostridium spp. (not perfringens) (63%/80%). pubmed.ncbi.nlm.nih.gov/20800151/ and academic.oup.com/cid/article/24…
10/½ blood cultures + for these bacteremia is usually due to contamination: CoNS, Bacillus, Corynebacterium, Propionibacterium, Microccous, Aerococcus spp, and viridans group streptococcus.
11/ However, the clinical context should be determined, especially with CONS which can cause endocarditis/joint/device infections.
12/Check out this helpful graphic by @VarunPhadke2
13/ In conclusion
1. Treat gram - as bacteremia
2. 2/2 bacteria on blood cultures drawn from different sites usually bacteremia
3. S. aureus, Enterococcus, most Strep usually true bacteremia, even in 1/2 cultures.
4. CoNS, Bacillus, Corynebacterium ect. usually contaminants
14/ In the first case, I would treat b/c 60-80 Clostridium spp true bacteremia and has a source, but it is never wrong to ask ID.
I should also clarify that when I say coag - staph, I really mean CoNS aside from S. lugdunensis which behaves in a more S. aureus-like manner.
ncbi.nlm.nih.gov/pmc/articles/P… Photo source: journals.asm.org/doi/10.1128/JC…

• • •

Missing some Tweet in this thread? You can try to force a refresh
 

Keep Current with Ann Marie Kumfer

Ann Marie Kumfer Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!

PDF

Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @AnnKumfer

16 Jul
1/ Understanding #ANA #tweetorial a collab w/ @MithuRheum
You are seeing a 30yo patient in the clinic who is ? an elevated ANA titer. A few months ago she had 2 weeks of joint pains & a rash. As part of the evaluation, an ANA was+ with a titer of 1:80. What do you do next?
2/ The goal of this tweetorial is to understand the significance of ANA
What is ANA?
What are the rheumatological and non-rheumatologic causes of ANA elevation?
What is the significance of the ANA titer?
What is the significance of the pattern of ANA elevation?
3/ ANA stands for antinuclear antibodies. What is in the nucleus? @sargsyanz reminds us that there are a lot of things in the nucleus, so a positive ANA could indicate antibodies targeting any of these structures.
Read 18 tweets
4 Feb
#medtwitter Can you have a completely normal CSF profile in autoimmune encephalitis? (answer forthcoming)
This table is from a 2019 review. Interestingly in LG11, IgLON5, and GlyR the majority have a completely normal CSF profile including oligoclonal bands. (ncbi.nlm.nih.gov/pmc/articles/P…)
What about MRI? In what percentage of autoimmune encephalitis is the MRI of the head normal?
Read 8 tweets
16 Dec 20
1/#tweetorial coagulopathy in liver disease and the role of vit K

Thanks to all who responded to the poll.
2/ Pts with cirrhosis are at higher risk of bleeding d/t ⬇️ factors, right? Not necessarily. In cirrhosis, there are ⬇️ in both anticoagulant and procoagulant factors in the liver. Additionally, factor VIII and VWF are usually increased.
3/ INR is only measuring a small part of the coagulation cascade, the extrinsic pathway (Factor VII). Additionally, variceal bleed is driven by ⬆️ portal pressure primarily.
Read 7 tweets
15 Dec 20
Do you give vitamin K to pts with cirrhosis presenting with elevated INR? I would love to hear your thoughts about the topic.
Here are a few questions about Vit K in cirrhosis I wanted to answer. Please post additional articles on the topics that you know of. Question 1: Is there proof that patients with cirrhosis are Vit K deficient?
3/ It is proposed that patients w/ cirrhosis are at ⬆️ risk for Vit K def. I could find very few studies about this. This study of pediatric pts w/ cholestatic liver disease had high prevalence, but very different pop from most adults w/ cirrhosis. pubmed.ncbi.nlm.nih.gov/19502999/
Read 19 tweets
7 Dec 20
#tweetorial To obtain blood cultures or not to culture? This was inspired by the ? from @reverendofdoubt and @GermHunterMD reply.

A pt w/ a hip fracture on POD1 has fever of 100.8. HR 90, BP 110/75, SpO2 96% ambient air. No localizing symptoms. Do you obtain blood cultures?
2/My reflex when I hear fever is to order blood cultures. It’s not wrong to make sure, right? As a resident, I remember grumbling at the ED for not ordering cultures on that CAP patient. First, what are the harms of ordering unnecessary blood cultures?
3/ Aside from the cost, there is a high rate of contamination on blood cultures from 0.6% to over 6%. In conditions with a low pretest probability of bacteremia, this represents a large prob that a + culture is contamination. ncbi.nlm.nih.gov/pmc/articles/P…
Read 15 tweets
8 Nov 20
1/ #tweetorial Next on the skeptical diagnosis series, I wanted to address cellulitis. I always feel a little angst when I am called to admit a patient w/ cellulitis. Does the patient really have cellulitis? In what % of pts diagnosed with cellulitis is the diagnosis incorrect?
2/ Here, I will focus and diagnosis and mimics. I plan to discuss mng of cellulitis later. Studies show that in 30-33% in patients diagnosed with cellulitis, the diagnosis is incorrect.
3/ Of those with an incorrect diagnosis, around 85% percent do not need hospitalization and 92% did not need antibiotics. Misdiagnosis is associated with millions in increased healthcare costs and up to 9000 nosocomial infections.
pubmed.ncbi.nlm.nih.gov/27806170/
pubmed.ncbi.nlm.nih.gov/29453874/
Read 15 tweets

Did Thread Reader help you today?

Support us! We are indie developers!


This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!

Follow Us on Twitter!

:(