Discover and read the best of Twitter Threads about #idmeded

Most recents (6)

Mandell ch. 29:
Macrolides do not have all that great oral bioavailability

Much higher tissue penetration than serum levels

Azithromycin tissue half-life is 2-4 days, so likely retains significant antibacterial activity for 5 days after a 5 day course

#IDTwitter #idmeded
Macrolides, clindamycin and chloramphenicol all bind at the same site of the 50S ribosome, preventing early chain elongation. They may competitively inhibit each other if used together
Resistance occurs by several mechanisms:
⚜️ Efflux pumps, one in Enterobacteriaceae (chromosomal) and a different one in Strep & Enterococcus species...the latter is called the M phenotype, is transposable, and only gives resistance to erythro, azithro and clarithro
Read 16 tweets
Mandell ch. 26:
Doxycycline acts on 70S ribosomes in mitochondria (in addition to 30S bacterial ribosomes), which gives it activity against protozoa and Plasmodium
#idtwitter #idmeded
We all know doxy (and tetra's in general) have awesome spectra of activity, but here's some factoids:

🔹They can be used for all Vibro spp.

🔹Listeria is only intermediately susceptible to doxy with larger inocula

🔹Minocycline has better activity against Acinetobacter
🔹For Lyme, MICs are actually lower to tetra than doxy

🔹M. hominis is usually susc; M.genitalium usually R to doxy

🔹Mino is best in class for Nocardia

🔹Myco species each vary in susc to each drug. There may be a role for doxy in MDR-TB!
Read 13 tweets
Mandell ch. 25:
There are so many more aminoglycosides than I ever thought 😅

AGs are characterized by concentration-dependent killing (high peak/MIC is desirable), the post-antibiotic effect, and synergism
#IDtwitter #idmeded
The higher the external (to the 🦠) concentration of AG, the more AG gets inside the 🦠 and the quicker it induces death...hence higher peak/MIC and AUC/MIC

Many many trials have shown once-daily dosing is = or superior to BID/TID in many different diseases/populations
Synergy has been shown in vitro and in animal models for many different abx with AGs in many different 🦠 ...but it doesn't translate into all clinical situations with Pseudomonas or Enterobacteriaceae

Synergy does not work for MRSA
Read 12 tweets
50yo F p/w acute onset fever, diarrhea. On exam is hypotensive and mildly confused. Sx started 2 days after return from Zambia. No malaria ppx. Smear w/ 30% P falciparum parasitemia. MICU concerned for cerebral malaria (CM). How can we confirm on #PhysicalExam ?#IDConsults
Cerebral malaria is defined by WHO as coma with peripheral parasitemia after other causes ruled out. In endemic regions this predominantly affects young kids due to immunologic naivety. Unfortunately, this defn is nonspecific as 40-70% of asymptomatic ppl may be parasitemic 2/
Pathophys of cerebral malaria is related to sequestration of parasitized RBCs in the CNS blood vessels...thanks to Hermann von Helmholtz’s invention of the ophthalmoscope in 1851 (with just a few updates from the original), we have a window to the vasculature of the CNS! 3/
Read 11 tweets
1/ Why tuberculosis has a preferential apical localization?
Is it the host? Is it the pathogen?
To answer this question, let’s review some cool stuff
#MedTwitter #IDTwitter #IDMedEd #IDDailyPearl

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2/ Arnold Rich stated: “There is no more puzzling circumstance in the pathogenesis of pulmonary tuberculosis […] than the peculiar fact that in the adult the disease begins almost invariably in the upper portion of the upper lobe“
3/ M. tuberculosis is an obligate aerobe (they have an absolute requirement of O2 to grow).
*Tubercle bacilli respire maximally in vitro at O2 concentrations of 20-40%
*Experimental infections in animals are inhibited by very low O2 concentrations
Am Rev Tuberc 1939; 40:157-68
Read 9 tweets
55 yo ♂️s/p RenalTx 10+yrs ago tacro/aza immunosuppressive, gardens & recent travel to home (Philippines), presents chronic progressive cough, constitutional features & single skin abscess, with non-cavitary RUL consolidation + diffuse ggo refractory to Levaquin...
100.1F, HR110s (near baseline), RR18 97% RA. Found to have mild AoC kidney injury, AoC hyponatretomia , mild hepatocellular injury. Procalcitonin 0.7.

Do you start antibiotics? If Yes: tell me which ones in comment
So before starting treatment...maybe should think about therapies....this was my 🐔 scratch DDx on back of article —> Think their stable and more Abx won’t help things I’m worried about acutely at this point
Read 10 tweets

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