# Lupus or Endocarditis: Infection Can Mimic Immunity

Antimicrobial therapy and source control are fundamental when infection is established. Reassess persistent renal disease rather than assuming every abnormality resolves with one label.

![Infographic: Lupus or Endocarditis: Infection Can Mimic Immunity](https://urinenephrology.org/visual-reference/images/mastery-sle-endocarditis.png?v=20261003c)

## Immune findings overlap

Endocarditis-associated glomerulonephritis can produce hematuria, low complement, and positive autoantibodies. These findings do not automatically establish primary autoimmune disease.

## Recognize infection clues

Fever, embolic findings, a murmur, device exposure, bacteremia risk, and systemic illness deserve attention even when serology suggests lupus or vasculitis.

## Use current microbiology criteria

Obtain appropriate blood-culture sets promptly, ideally before antibiotics when feasible, and arrange echocardiography according to suspicion. The 2023 Duke-ISCVID criteria removed the old requirements for culture timing and separate venipunctures. Do not delay collection to manufacture a 12-hour interval.

## Do not let antibodies outrank infection

Positive ANCA or other autoimmune serology can occur with endocarditis. Persistent bacteremia, embolic findings, or valve/device evidence should drive infection treatment and source control. Before immunosuppression, reconcile cultures, imaging, kidney pathology, and the urgency of organ injury with the relevant teams.

## Interpret tissue in context

Biopsy patterns and immune deposits help, but infection-associated and autoimmune processes can share features. Clinical microbiology remains central.

## Treat the cause

Antimicrobial therapy and source control are fundamental when infection is established. Reassess persistent renal disease rather than assuming every abnormality resolves with one label.

## Supporting evidence

- [Supporting guideline or source](https://pmc.ncbi.nlm.nih.gov/articles/PMC10681650/)

## Source lessons

- [sle vs ie](https://urinenephrology.org/mastery/cases/sle-vs-ie.html)
- [infection associated gn](https://urinenephrology.org/mastery/glomerular/infection-associated-gn.html)

Read alongside the full lessons; the findings and decisions shown here require the stated clinical context.