Marcel Behr
@mbehr-mcgill.bsky.social
Clinician-scientist. Epidemiology and pathogenesis of mycobacterial infections.
Excited to see the PhD work led by Sarah Danchuk published today. Virulence hierarchies within the Mycobacterium tuberculosis complex. Thanks to all the authors and collaborators, and especially kudos to Sarah: www.pnas.org/doi/10.1073/...
https://pnas.org/doi/10.1073/pn…
October 16, 2025 at 6:39 PM
Excited to see the PhD work led by Sarah Danchuk published today. Virulence hierarchies within the Mycobacterium tuberculosis complex. Thanks to all the authors and collaborators, and especially kudos to Sarah: www.pnas.org/doi/10.1073/...
It has been often observed that TB rates go up from childhood to adolescence, suggesting that children under 14 are relatively resistant and/or adolescents are more susceptible. Could the rise in incidence be explained instead by transmission effects you report?
Across age groups, TB exposure typically peaked in adolescence. However, transmission contributions by age varied across regions with the highest proportion from adolescents aged 15-24 in AMR and SEAR, adults aged 35-44 in AFR and EUR, and older adults 65+ in EMR and WPR.
[NOT YET PEER REVIEWED]
[NOT YET PEER REVIEWED]
October 12, 2025 at 5:37 PM
It has been often observed that TB rates go up from childhood to adolescence, suggesting that children under 14 are relatively resistant and/or adolescents are more susceptible. Could the rise in incidence be explained instead by transmission effects you report?
Starting conversation for mycobacteria researchers. 1) mycobacteria have strange cell wall, 2) mycobacterial infections are hard to treat. Is 1) the CAUSE of 2)? For broad spectrum antibiotics that work (rifampin, levofloxacin, linezolid), do they get into mycobacteria at lower concentrations?
Marcel Behr @mbehr-mcgill.bsky.social is on here. Not sure about Lali Ramakrishnan. I’m a nobody, but in my brief time working on TB, I was super impressed by their willingness to question what had become a widely cited dogma.
October 11, 2025 at 3:24 PM
Starting conversation for mycobacteria researchers. 1) mycobacteria have strange cell wall, 2) mycobacterial infections are hard to treat. Is 1) the CAUSE of 2)? For broad spectrum antibiotics that work (rifampin, levofloxacin, linezolid), do they get into mycobacteria at lower concentrations?
I thought it was going outside in winter without a hat....
Kicking off the #CausalIntroCourse in Leeds. Hoping this will finally give me the tools to convince my mum that walking around the house barefoot ^^doesn’t^^ cause a cold.
July 7, 2025 at 1:07 PM
I thought it was going outside in winter without a hat....
Sihem Belhocine put this quote at the start of her thesis: "If many remedies are prescribed for an illness, you may be certain that the illness has no cure." Anton Chekhov, The Cherry Orchard, 1904 (the year he died of tuberculosis). Does this adage hold true in 2025?
April 12, 2025 at 3:49 PM
Sihem Belhocine put this quote at the start of her thesis: "If many remedies are prescribed for an illness, you may be certain that the illness has no cure." Anton Chekhov, The Cherry Orchard, 1904 (the year he died of tuberculosis). Does this adage hold true in 2025?
Amazing thesis work led by Sarah Danchuk now submitted for review and posted as preprint: ssrn.com/abstract=51598…. Short summary: M. bovis & M. orygis manifest enhanced virulence compared to M. tuberculosis in natural host model (calves) and small animal model (mice).
March 4, 2025 at 11:56 PM
Amazing thesis work led by Sarah Danchuk now submitted for review and posted as preprint: ssrn.com/abstract=51598…. Short summary: M. bovis & M. orygis manifest enhanced virulence compared to M. tuberculosis in natural host model (calves) and small animal model (mice).
Question to academics: I've been on several editorial boards before, but until now, never been asked by to sign a 16-page legal contract, including a section on my obligations. Unpaid role. Is this the new norm?
February 18, 2025 at 1:28 PM
Question to academics: I've been on several editorial boards before, but until now, never been asked by to sign a 16-page legal contract, including a section on my obligations. Unpaid role. Is this the new norm?
Hi Peter,
A further point. It's brilliant that UK publishes its M. Bovis data. Now that WHO and WOAH recognize that definition of zoonotic TB extends to M. Orygis as well, I would be curious to see the same type of data for M. Orygis cases. So far, just scattered case series, nothing systematic.
A further point. It's brilliant that UK publishes its M. Bovis data. Now that WHO and WOAH recognize that definition of zoonotic TB extends to M. Orygis as well, I would be curious to see the same type of data for M. Orygis cases. So far, just scattered case series, nothing systematic.
Just checked, and notification data for UK here, nicely disaggregated by age, sex, and immigration status. See also link to .csv files. In UK consistently more men than women notified with M. Bovis
Mycobacterium bovis notifications to national tuberculosis surveillance: UK, 2000 to 2023
www.gov.uk
January 30, 2025 at 8:55 PM
Hi Peter,
A further point. It's brilliant that UK publishes its M. Bovis data. Now that WHO and WOAH recognize that definition of zoonotic TB extends to M. Orygis as well, I would be curious to see the same type of data for M. Orygis cases. So far, just scattered case series, nothing systematic.
A further point. It's brilliant that UK publishes its M. Bovis data. Now that WHO and WOAH recognize that definition of zoonotic TB extends to M. Orygis as well, I would be curious to see the same type of data for M. Orygis cases. So far, just scattered case series, nothing systematic.
Thanks!
Just checked, and notification data for UK here, nicely disaggregated by age, sex, and immigration status. See also link to .csv files. In UK consistently more men than women notified with M. Bovis
Mycobacterium bovis notifications to national tuberculosis surveillance: UK, 2000 to 2023
www.gov.uk
January 29, 2025 at 3:14 PM
Thanks!
Hi Peter. I don't know about exposure. Harder to do in immigrants to e.g., Canada, Australia asking about exposure in country of birth. Maybe can be done in places where local exposure? Are there good data in the UK?
Marcel - apologies I completely missed this post! Interesting, and would be good to systematically collate data. Would there be sex differences in exposure to infected animals, ie women more likely to care for/milk cattle?
January 29, 2025 at 2:06 PM
Hi Peter. I don't know about exposure. Harder to do in immigrants to e.g., Canada, Australia asking about exposure in country of birth. Maybe can be done in places where local exposure? Are there good data in the UK?
Compelling analysis suggesting that M:F difference in TB rates driven by differences in rates of Mtb infection. Consistent with old (2000) analysis of genotypic clustering (PMID: 10654640). But why do zoonotic TB series often have flipped ratios? doi: 10.1093/infdis/jiae124
New preprint (with all pre-print caveats!) tinyurl.com/589ffhu4 on Mtb infection risk by sex & age.
Men are at higher risk of #tuberculosis v women- but unclear how much driven by higher infection vs progression to disease. We meta-analysed Mtb immunoreactivity surveys to find out more🧵 #tbsky
Men are at higher risk of #tuberculosis v women- but unclear how much driven by higher infection vs progression to disease. We meta-analysed Mtb immunoreactivity surveys to find out more🧵 #tbsky
Sex Differences in the Risk of Mycobacterium Tuberculosis Infection: A Systematic Review and Meta-Analysis of Population-Based Immunoreactivity Surveys
Background: Tuberculosis (TB) killed 1·25 million people globally in 2023. Men have a 1·7-fold higher TB incidence than women, but it is not known to what exten
papers.ssrn.com
January 10, 2025 at 12:27 PM
Compelling analysis suggesting that M:F difference in TB rates driven by differences in rates of Mtb infection. Consistent with old (2000) analysis of genotypic clustering (PMID: 10654640). But why do zoonotic TB series often have flipped ratios? doi: 10.1093/infdis/jiae124
I believe most isolates from pre-2020. Resistance developing or already established?
⚠️ Bit of an alarm bell to MDR-TB regimen BPaL/M - resistance to constituent antibiotics developing and transmission of such strains already occurring
#TBSky #IDSky @nejm.org
www.nejm.org/doi/10.1056/...
#TBSky #IDSky @nejm.org
www.nejm.org/doi/10.1056/...
Transmission as a Key Driver of Resistance to the New Tuberculosis Drugs | NEJM
Whole-genome sequencing was used to show that resistance to newer antituberculosis
drugs is present in at least 27 countries and that up to a quarter of this resistance
may be due to person-to-...
www.nejm.org
January 5, 2025 at 5:02 PM
I believe most isolates from pre-2020. Resistance developing or already established?
Agree with treating Legionella. Where are the best data on macrolide treatment and outcome of CAP due to Mycoplasma?
"population level" being the key expression here - there will be specific cases where adjunctive macrolides are beneficial (i.e. the actual mycoplasma / legionella cases out there). The trick is to identify them without needing to treat every case of CAP #IDSky
December 28, 2024 at 5:38 PM
Agree with treating Legionella. Where are the best data on macrolide treatment and outcome of CAP due to Mycoplasma?
Reposted by Marcel Behr
In this report, investigators assessed the efficacy of levofloxacin for the prevention of secondary cases of tuberculosis among household contacts of persons with multidrug-resistant tuberculosis. Full VQUIN MDR trial results: nej.md/41BHEf5
#MedSky #IDSky
#MedSky #IDSky
December 20, 2024 at 2:09 PM
In this report, investigators assessed the efficacy of levofloxacin for the prevention of secondary cases of tuberculosis among household contacts of persons with multidrug-resistant tuberculosis. Full VQUIN MDR trial results: nej.md/41BHEf5
#MedSky #IDSky
#MedSky #IDSky
Pre-XDR Mycobacterium tuberculosis in cattle. Plus some M. orygis academic.oup.com/ofid/advance...
Recovery of Mycobacterium tuberculosis complex isolates including pre-XDR strains from Cattle at a Slaughterhouse in Chennai, India
AbstractBackground. India has the highest global burden of human tuberculosis (TB) and the largest cattle herd with endemic bovine TB. However, the extent
academic.oup.com
December 20, 2024 at 12:02 AM
Pre-XDR Mycobacterium tuberculosis in cattle. Plus some M. orygis academic.oup.com/ofid/advance...
Sarah Danchuk at PhD defense, presenting her favourite figure contrasting the host reservoirs of Mycobacterium tuberculosis complex.
December 9, 2024 at 3:16 PM
Sarah Danchuk at PhD defense, presenting her favourite figure contrasting the host reservoirs of Mycobacterium tuberculosis complex.
Here is the reference for macrolide susceptibility of certain BCG strains PMID: 14693532
In addition to standard M. bovis drugs, 'late' BCG strains are macrolide susceptible because of deletion of rv1988, in the RD2 region. This gives another therapeutic option if it was oncoTice
Tagging #TBSky for their thoughts. Any specific concerns about standard bovis therapy.
December 2, 2024 at 1:05 PM
Here is the reference for macrolide susceptibility of certain BCG strains PMID: 14693532
In addition to standard M. bovis drugs, 'late' BCG strains are macrolide susceptible because of deletion of rv1988, in the RD2 region. This gives another therapeutic option if it was oncoTice
Tagging #TBSky for their thoughts. Any specific concerns about standard bovis therapy.
December 2, 2024 at 1:00 PM
In addition to standard M. bovis drugs, 'late' BCG strains are macrolide susceptible because of deletion of rv1988, in the RD2 region. This gives another therapeutic option if it was oncoTice
In much of medicine, new drugs are twinned with companion diagnostics. Blood pressure monitoring for antihypertensives; bone densitometry for osteoporosis drugs, etc. How can we ensure drug susceptibility testing is developed and deployed for the next TB antibiotic?
Bedaquiline has been a great development in the treatment of drug-resistant TB. But it's future is uncertain due to rising resistance levels. Great review here.... #IDSky #Microsky #Infectiousdiseases #TB #Tuberculosis
www.sciencedirect.com/science/arti...
www.sciencedirect.com/science/arti...
Bedaquiline: what might the future hold?
Tuberculosis drug development has stagnated for decades, so the recent availability of bedaquiline is welcome. Bedaquiline-containing regimens, now th…
www.sciencedirect.com
December 1, 2024 at 12:08 AM
In much of medicine, new drugs are twinned with companion diagnostics. Blood pressure monitoring for antihypertensives; bone densitometry for osteoporosis drugs, etc. How can we ensure drug susceptibility testing is developed and deployed for the next TB antibiotic?
Natural experiments, although imperfectly controlled, can be more creative, and therefore more informative, than the experiments we design in the lab. Agree/disagree/both?
November 26, 2024 at 12:33 PM
Natural experiments, although imperfectly controlled, can be more creative, and therefore more informative, than the experiments we design in the lab. Agree/disagree/both?
They are also evaluated differently, generally using randomized responders rather than treat-through studies. Detailed in: www.gastrojournal.org/article/S001...
This is a bit wild
Why should there be different legal protections for biologics vs small molecule drugs in the US?! 🤷♂️
#medsky #legal #patent
jamanetwork.com/journals/jam...
Why should there be different legal protections for biologics vs small molecule drugs in the US?! 🤷♂️
#medsky #legal #patent
jamanetwork.com/journals/jam...
Legal Protections for Biologics vs Small-Molecule Drugs in the US
This Special Communication analyzes and compares development times, clinical trial success rates, research and development costs, patent protection, market exclusivity periods, revenues, and treatment...
jamanetwork.com
November 26, 2024 at 1:09 AM
They are also evaluated differently, generally using randomized responders rather than treat-through studies. Detailed in: www.gastrojournal.org/article/S001...
Do urine tests offer a useful sample in PWHIV because they have unrecognized renal TB? Or is there a DNAemia / LAMemia that is filtered through the glomeruli into the urine?
Important results for TB diagnosis in PWHIV!
Urine-Xpert Ultra for the diagnosis of #tuberculosis in people living with #HIV: a prospective, multicentre, diagnostic accuracy study
www.sciencedirect.com/science/arti...
Urine-Xpert Ultra for the diagnosis of #tuberculosis in people living with #HIV: a prospective, multicentre, diagnostic accuracy study
www.sciencedirect.com/science/arti...
November 21, 2024 at 5:01 PM
Do urine tests offer a useful sample in PWHIV because they have unrecognized renal TB? Or is there a DNAemia / LAMemia that is filtered through the glomeruli into the urine?
International observations consistent with what we saw across subgroups in San Francisco. But is it gender or sex or a bit of both? pubmed.ncbi.nlm.nih.gov/10654640/
November 19, 2024 at 1:30 PM
International observations consistent with what we saw across subgroups in San Francisco. But is it gender or sex or a bit of both? pubmed.ncbi.nlm.nih.gov/10654640/
Agree we need better data on infection. Will data drive the need for a test to distinguish cleared from current infection? Or is a test needed first to generate firm estimates? Would be ++ helpful in clinic to know who is infected today, before writing a prescription.
Read this amazing preprint today: ~2% (156M) of the world recently infected with #tb.
Between 4.9%~7.7% have viable infection.
But emphasises we need +++ data on Mtb infection
@aschwalbc.bsky.social @kchorton.bsky.social @petedodd24.bsky.social @reinhouben.bsky.social @hannahrickman.bsky.social
Between 4.9%~7.7% have viable infection.
But emphasises we need +++ data on Mtb infection
@aschwalbc.bsky.social @kchorton.bsky.social @petedodd24.bsky.social @reinhouben.bsky.social @hannahrickman.bsky.social
November 19, 2024 at 12:41 AM
Agree we need better data on infection. Will data drive the need for a test to distinguish cleared from current infection? Or is a test needed first to generate firm estimates? Would be ++ helpful in clinic to know who is infected today, before writing a prescription.
Reposted by Marcel Behr
Read this amazing preprint today: ~2% (156M) of the world recently infected with #tb.
Between 4.9%~7.7% have viable infection.
But emphasises we need +++ data on Mtb infection
@aschwalbc.bsky.social @kchorton.bsky.social @petedodd24.bsky.social @reinhouben.bsky.social @hannahrickman.bsky.social
Between 4.9%~7.7% have viable infection.
But emphasises we need +++ data on Mtb infection
@aschwalbc.bsky.social @kchorton.bsky.social @petedodd24.bsky.social @reinhouben.bsky.social @hannahrickman.bsky.social
November 18, 2024 at 3:59 PM
Read this amazing preprint today: ~2% (156M) of the world recently infected with #tb.
Between 4.9%~7.7% have viable infection.
But emphasises we need +++ data on Mtb infection
@aschwalbc.bsky.social @kchorton.bsky.social @petedodd24.bsky.social @reinhouben.bsky.social @hannahrickman.bsky.social
Between 4.9%~7.7% have viable infection.
But emphasises we need +++ data on Mtb infection
@aschwalbc.bsky.social @kchorton.bsky.social @petedodd24.bsky.social @reinhouben.bsky.social @hannahrickman.bsky.social