Providencia rettgeri as an unusual pathogen in diabetic foot osteomyelitis: A case report and literature review.

Providencia rettgeri is a Gram-negative bacterium, rarely reported as a cause of diabetic wound infections. Its frequent resistance to β-lactams and carbapenems limits treatment options, especially in immunocompromised patients. We present the case of a 59-year-old unhoused male living with diabetes, peripheral artery disease, and prior bilateral transmetatarsal amputations who presented with a University of Texas 3B diabetic foot ulcer. Magnetic resonance imaging showed osteomyelitis of metatarsals 2-4, and bone biopsy grew Providencia rettgeri and Proteus mirabilis. The patient declined further surgery and was treated with 6 weeks of cefepime and metronidazole, with outpatient wound care, achieving wound closure in 3 months. We performed a systematic scoping literature review on Providencia rettgeri wound infections in humans, detailed below, which identified only eight studies that met our inclusion and exclusion criteria. Most cases involved snake bites or critically ill patients, and none documented lower extremity bone involvement. Resistance patterns varied, but co-infection was common. Given its rarity and potential for multidrug resistance, Providencia rettgeri should remain on the differential for non-healing diabetic wounds. This case expands the limited literature and highlights the importance of culture-driven antibiotic therapy in complex infections. Recognition of Providencia rettgeri as a rare but clinically significant pathogen in diabetic foot osteomyelitis has implications for empiric antibiotic selection and clinical outcomes.