Lawsonella clevelandensis breast abscess in a young woman with uncontrolled type 1 diabetes: a case report.

BACKGROUND: Lawsonella clevelandensis (L. clevelandensis) is a recently described anaerobic, partially acid-fast Gram-positive bacillus that has been increasingly recognized as an opportunistic pathogen causing abscess formation in immunocompromised hosts. However, breast abscess caused by this organism in young diabetic patients is rarely reported. CASE PRESENTATION: A 22-year-old woman with a 5-year history of poorly controlled type 1 diabetes mellitus presented with a one-week history of left breast pain and erythema. Ultrasound revealed mastitis with abscess formation. Needle aspiration yielded purulent material that was partially acid-fast on staining but negative for Mycobacterium tuberculosis complex PCR. Conventional aerobic culture showed no growth, while anaerobic culture yielded colonies after 7 days of incubation. The isolate was identified as L. clevelandensis by 16S rRNA gene sequencing (99.722% similarity). The patient received percutaneous drainage, antibiotics, and intensive insulin therapy, with marked clinical improvement. CONCLUSION: This case highlights the diagnostic challenges posed by L. clevelandensis due to its fastidious growth and misleading acid-fast positivity. It should be suspected in diabetic patients with breast abscesses when conventional cultures are negative and tuberculosis is excluded. Prolonged anaerobic culture and molecular methods are essential for definitive diagnosis.