1/ #IDTwitter and #IDFellows, here is another #IDboardreview question: 20F p/w pharyngitis w/fever. There is no cough. Exam: Cervical adenopathy; tonsillar exudate. Rapid Strep antigen test pos. You start to prescribe her Amoxicillin but there is an allergy alert.
2/ She reports an allergic reaction to penicillin around age 8 or 9. She had a rash but no other symptoms. It resolved following discontinuation of med. She did not receive any treatment. Which of the following would you do next?
3/ Today we are going to talk about everyone’s favorite – #penicillin #allergy!
4/ Penicillin is the most commonly reported drug allergy (followed by sulfonamides) documented in patient charts. However, most of these are documented based on patient account and not observed reactions. PMID: 26970431
5/ PCN allergy is assc w/worse outcomes. The avoidance of beta-lactams when they are the reatment of choice, has been associated with incr. risk of drug resistant infections, C difficile colitis and increased hospital LOS.
PMID: 29950489; 24188976; 27402820
6/ How does penicillin cause allergy? This great review from @NEJM (PMID: 31826341) explains. The beta-lactam ring has the ability to bind lysine residues in the plasma and can form penicilloyl polylysine, which stimulates antibody production.
7/ Following sensitization, rechallenge of penicillin can lead to IgE mediated antibody response, which leads to mast cell degranulation and the classic presentation of anaphylaxis. Source: NEJM
8/ Penicillin, and beta-lactams in general, are also associated with other types of allergic reactions, including T Cell-mediated (Type IV), IgG-mediated (Type II), and immune complex-mediated (Type III) reactions. However, anaphylaxis is the most feared adverse effect.
9/ Penicillin allergy can be deadly, but a significant proportion of people do not have real allergy when tested or re-challenged. This equates to worsened patient outcomes for no reason. PMID: 30644987
Image (skin testing) from JAMA - PMID: 30644984
10/ How can you take PCN allergy off of pts’s charts? One way is to perform skin testing, which has been shown to be safe and effective (PMID: 24565482). Alternatively, a recently developed decision support tool called PEN-FAST can help to delabel patients (PMID: 32176248).
11/ PEN-FAST was derived from data on > 600 pts and was validated in > 900 pts. A score < 3 equates to a NPV of 96.3% and is suggested a cutoff for possible oral challenge w/skin testing. In this scenario our patient had a score of 0, w/NPV of 99.4%. qxmd.com/calculate/calc…
12/ In our patient, the chance of any hypersensitivity response would have been approx 0.6%.

Ok #IDTwitter and #IDFellows, after this tweetorial do you feel more confident in using penicillin in low-risk patients based on the PEN-FAST score?

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More from @ID_fellows

16 Sep
1/ Follow up for our #IDFellows and #IDTwitter on an #IDCase - 25 year old female with behcet's disease and chronic pain who presents for positive T Spot done for screening. Started on Rifampin for latent TB Infection. She calls 3 days later with diffuse pain.
2/ Great job, #IDTwitter, honing in on the issue! This was intentionally vague to stimulate discussion. As you alluded to, the key lies in what else she was taking. But first, what might we worry about as adverse effects Rifampin?
3/ Allergic reactions to rifampin are relatively rare though they have been described. However, patients may experience flushing, rash and itching that is unrelated to hypersensitivity. Rifampin can often be continued in these patients. PMID: 10575418
Read 10 tweets
1 Sep
Thanks to all that participated in our 1st live #IDFellowCase yest! Here is a wrap-up review tweetorial for reference + those who missed it.

Special thanks to @MDdreamchaser!

If you have feedback OR want to sign up to do a future case, use this form:forms.gle/cV4bRezYUCp6VR…
A case of 70F with ring-enhancing brain/lung lesions was presented. Here is how @MDdreamchaser walked thru the case:
1⃣Define pt risk of infection (e.g. splenectomy, steroid use)
2⃣Take presenting clinical syndrome
3⃣Tempo of illness: abrupt? gradual?
In this case, co-occurrence of brain-lung nodules was helpful clue

🖼️Infographic below

Also check out this 🧵 from @WuidQ

⭐️One other pearl. Embolizing disease might include endocarditis, Lemierre's dz, infectious aortitis, infected cardiac thrombus
Read 14 tweets
19 Aug
72F with CML had persistent fever ~102F, cough. CT chest with focal consolidation in LLL. Sputum cx: Klebsiella pneumoniae. Serum BDG, GM negative.

Was on Vanc/Cefepime/LAmB, now narrowed to Cefepime + afebrile 24h

Duration of Cefepime?
#IDTwitter #IDMedEd #IDFellows
Today’s #tweetorial is on fever + neutropenia!

Up to 50% pts with solid tumors & >80% pts with hem malignancy will develop fever during chemo cycle assoc’d with neutropenia
Only 20-30% of these identify clinical infection
Only 10-25% bacteremia
The very basics:
🔹Here is the classic article from 1966 that demonstrated ⬆️susc to infection as neutrophils<500
🔹Freq and severity of infection inversely proportional to neutrophil count
🔹Risk of severe infection and BSI greatest at ANC <100
Read 15 tweets
12 Aug
1/ Hey #IDFellows, here is a new #IDTwitter Tweetorial: 24F w/1 wk hx pharyngitis + 1d cough & SOB. VS T 39.3C, RR 23, SpO2 92%, HR 112. Exam with tonsillar swelling & erythema; L neck pain and swelling on palpation. CXR w/peripheral nodular opacities. Best empiric abx?
2/ Lemierre’s syndrome = #eponym for suppurative thrombophlebitis of the jugular vein. Often preceded by pharyngitis +/- neck swelling. Commonly associated with pulmonary septic emboli. Check these #NEJM Clinical Images:
3/ Most common organisms include Fusobacterium necrophorum >>> other fusobacterium > anaerobic streptococci. Fusobacterium necrophorum, an anaerobic gram-negative rod, seems to be distinctively adept at causing septic thrombophlebitis.
Read 11 tweets
11 Aug
Thank you all for the enthusiasm! #WeAreID #IDTwitter #IDfellows

36F w/ fever for 6 days after the day of returning from Manzini, Eswatini. Stayed there 15 days, visited rural fields. Also, weakness, myalgia, night sweats, sore throat

What is your approach?
Many approaches possible.

Check out this amazing tweetorial by @BoggildLab

1⃣ Common things being common: In addition to RTI, gastroenteritis, SSTI, UTI/STI, DO NOT want to miss: MDRT (malaria, dengue, rickettsial infections, typhoid fever)
Or this great video tutorial by @EvelynSongMD and @CPSolvers


2⃣Beware of transmissible infections➡️infection prevention: Ebola, Marburg, Lassa, TB, MERS, SARS, Influenza
Read 13 tweets
10 Aug
First #IDtweetorial

65M w/persistent MRSA bacteremia on day 4 of Vancomycin. Last Vanc trough 18.7. MRSA is Vanco Susc.
Primary team asking to change therapy.

What would you do? (Poll)

Let’s review some of the evidence to guide our decision
#IDTwitter #IDfellows
First, what is considered persistent bacteremia?
In a frequently cited study, bacteremia in pts w/MRSA IE lasted a median of 7d w/Vanco, w/ no unusual complications
This led to believe that slow clearance was usual for some cases of MRSA IE
However, recent studies have shown significant increased risk in mortality and metastatic complications after 3 days of bacteremia.
Read 13 tweets

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