The Constipated Colonizer

An 87-year-old patient presented with acute back pain, without neurologic deficits or history of trauma. MRI showed T2 Hyperintensity at L2-L3, concerning for possible discitis/osteomyelitis.

We paused antibiotics and obtained both blood cultures and a lumbar spine biopsy.

To our surprise, both grew Lactobacillus. A probiotic. A gut buddy. The kind of microbe you expect in yogurt, not in an infected vertebral disc.

But with systemic symptoms and positive cultures from two separate sites, we had to take it seriously.

So… how did it get there?

• Three dental procedures in the past 12 weeks – no prophylactic antibiotics
• A history of TAVR
• Chronic constipation, managed with daily probiotics

Two main theories emerged:

1. Hematogenous seeding following dental manipulation
2. Translocation from altered gut integrity (stercoral colitis could have done it)
3. The universe was feeling spicy

Given his valve history and bacteremia, we considered endocarditis. While Lactobacillus is often dismissed as a contaminant, it has been associated with endocarditis in patients with structural heart disease — and even linked to increased mortality when not taken seriously. ¹

Using the 2023 Modified Duke Criteria, we determined he met criteria for possible infective endocarditis based on three minor criteria: predisposition (TAVR), positive blood cultures not meeting major criteria, and vascular phenomena. His TTE was unchanged from a few months prior. We discussed the role of TEE with the patient and his family as a tool to assess for valvular destruction that might require surgery — but given the risk, and the fact that it wouldn’t alter our management, we elected not to pursue it.

Once our lab confirmed Lactobacillus susceptibilities, we discharged him on six weeks of daptomycin.

---

Why this stuck with me:

• Hold antibiotics when feasible, it improves culture yield
• Get the biopsy when it will change management
• Work up endocarditis when the story supports it
• Address constipation – a full colon is a full-body experience

Bottom line: Even your “friendly flora” can go rogue under the right circumstances. Stay curious and remember: sometimes the most innocuous organisms are the ones to watch.

1. Salvagno S, et al. Lactobacillus Species Bloodstream Infections in Adults: A 15-Year Multicenter Retrospective Study. Open Forum Infect Dis. 2024; 11(3): ofae089. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10812763 ↩︎