Mycotic aneurysm secondary to M. bovis

Images of Infectious Diseases

70M with PMH of bladder cancer and a recent endovascular repair of saccular aortic aneurysm is now referred to your hospital because of FUO and this (photo).

What is your DDx? What is your approach to Dx? Case details and #MayoIDQ MCQ to follow…

Thank you for providing an extensive list of DDx – from the most common (staphylococcus, salmonella) to the unusual (T. whipplei, T. pallidum)… and every pathogen in between.

Read on for the case details…

2y ago: bladder CA s/p BCG /TURBT

1 y ago: AAA on CT surveillance —> Rx: endovascular repair

4 mo ago: back pain/fever
CXR (-). MRI spine (-). Routine blood cultures (-). PET CT (photo).

Exposures: cattle farmer, chicken, pets: cat, dog, turtle

What is likely pathogen?

As some suggested, the saccular aortic aneurysm was likely mycotic.

#Mycotic aneurysm
Mechanisms:
1. Direct inoculation (vascular injury)
2. Direct extension (from infected tissues around the vessel)
3. Microbial seeding (during bacteremia)
4. Septic emboli (endocarditis)

#Mycotic aneurysm
Microbiology (most common)
1. #Staphylococcus spp. (S aureus most common)
2. #Salmonella spp.

Plus, many others: pneumococcus, syphilis, mycobacterium, Q fever, fungi, and many more… as you suggested!

We have previously discussed here a case of nontyphoidal Salmonella mycotic aneurysm associated with enteritis.

See thread on this link.

We have also discussed a second case of salmonella mycotic aneurysm associated with “tiger meat” consumption.

See thread on this link.

Clues in this case:
1. #BCG#Mycobacterium bovis
2. Cattle – #Brucella
3. Endovascular procedure – #Staphylococcus
4. Chicken / turtle – #Salmonella

Chronicity favors Mycobacterium and Brucella over Staphylococcus aureus and Salmonella spp.

Clues in this case: “routine blood culture (BC) is negative”

BC should be + in patients with vascular infections due to Staphylococcus and Salmonella, especially w/ endovascular stent

Brucella also grows in automated BC systems. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC85661/

Case diagnosis:
#Mycobacterium #bovis #mycotic #aneurysm with periaortic / psoas abscess

Abscess drained: AFB+

Explor lap / debride / resect infected aortic stent: AFB+, MTB PCR+, culture: MTB complex (PZA monoresistance)

Rx: RIF-INH-EMB x 2 mo then RIF-INH x 7mo planned

#BCG Bacillus Calmette-Guerin (M bovis) Rx of non-muscle-invasive bladder cancer (NMIBC)

Mechanism of anti-tumor activity: unknown but presumed immune related

Standard intravesical Rx for NMIBC for over 4 decades!

Review and history here:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6411413/

Learn more about #Mycobacterium #bovis infection in this recent tweetorial of a case likely acquired from ingestion of unpasteurized milk products.

Please review this thread link!

Thank you for your participation!

Originally tweeted by Mayo Clinic Infectious Diseases (@MayoClinicINFD) on 9 August, 2020.

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