Possible Bone Infection from Flu Shot

The results of my bone biopsy taken during surgery for my Shoulder Injury Related to Vaccine Administration (SIRVA) came back positive for a slow-growing bacterium, Propionibacterium acnes (P. acnes), that commonly lives in the skin of the shoulder and head area. Assuming the result is not a false positive, the bacteria were carried by the flu shot through my skin and inoculated the bone when the shot hit the greater tuberosity of the humeral head.

While a properly-administered flu shot to the deltoid muscle may also carry this bacterium to the injection site (swabbing the skin with alcohol is not enough to completely eliminate P. acnes, which also lives deeper in the dermis), in the muscle the immune system can fight it, and infections following vaccinations to the deltoid muscle are rare. A mis-administered shot to the shoulder joint and bone (instead of the muscle) deposits the bacterium in an “immunologically diminshed” region where the body may be unable to fight the invader: “Direct seeding of bacteria into bone can occur as a result of open fractures, insertion of metallic implants or joint prostheses, human or animal bites and puncture wounds” (as explained here).

My exact type of infection, while essentially never observed in vaccinations because it requires spectacular mistakes to be made during injection, is more commonly observed as a complication of shoulder surgery. Most of the experience in treating it comes from that analog. It is slow-growing, difficult to detect, and often does not cause a fever or other typical symptoms in infection, including telltale signatures in blood—it just causes pain and stiffness in the shoulder post-operatively (or, in my case, post-vaccination). If left untreated, or even if treated, it can cause major damage and require repeated shoulder surgeries (debridement of irreparably damaged bone) or even shoulder replacement. It is bad news.

My MRIs at 1 month and 6 months post-flu shot, showing a growing bone marrow edema in the humeral head.

We don’t know for sure if the bone marrow changes on my MRI, which I previously attributed to the purely inflammatory effects of SIRVA in this post, are being caused by this infection, which would then make it called “osteomyelitis” or bone marrow infection. There are more or less 3 possibilities for what could be going on here:

  1. The biopsy result is real, and the slow-growing P. acnes infection is responsible for my pain and bone marrow edema on the MRI. (This is plausible—my pain took an increase at about 2.5 months after the shot, which would correspond reasonably well with the timeframe for P. acnes infection to proliferate.)
  2. The result is a false positive on the biopsy, and the pain and bone marrow edema on my MRI are from the usual SIRVA mechanisms seen in many cases and described in an earlier post.
  3. The result of the biopsy is real (there is P. acnes), but it is not “pathogenic”, i.e., is not responsible for my pain and growth of the bone marrow edema.

Because the risk of not treating a bone infection are too great, especially for someone who hopes to return to overhead sports (in my case, rock climbing), we have no choice but to assume #1 is the case and treat the possible infection aggressively. The standard treatment is intravenous (IV) antibiotics for several weeks.

On July 19th I had a Peripherally Inserted Central Catheter (PICC) line installed; it goes from a vein in the arm into the chest near the heart. I get an infusion of antibiotics every day through the line for 6 weeks. It’s been almost 2 weeks so far. I’ll write another post about the PICC line experience, but that’s the update on this unusual twist in my SIRVA case for now.

 

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