# A Case of Necrotizing Fasciitis Caused by Mixed Infection of Arcanobacterium haemolyticum and Streptococcus agalactiae

## TL;DR

A rare case of severe necrotizing fasciitis caused by a mixed infection of two bacteria in a diabetic patient is reported, highlighting the danger of these pathogens in immunocompromised individuals.

## Contribution

Reports a rare clinical case of necrotizing fasciitis caused by a mixed infection of A. haemolyticum and S. agalactiae in a diabetic patient.

## Key findings

- A. haemolyticum and S. agalactiae caused severe necrotizing fasciitis in a patient with diabetes mellitus.
- The infection progressed rapidly despite aggressive treatment, requiring multiple amputations.
- The case highlights the importance of considering mixed infections in severe soft tissue infections.

## Abstract

Arcanobacterium haemolyticum (A. haemolyticum), a Gram-positive, anaerobic, rod-shaped bacterium, is typically associated with pharyngitis and skin infections but can also cause severe, life-threatening infections such as sepsis and necrotizing fasciitis (NF), particularly in immunocompromised patients. We report a case of severe NF of the lower extremity caused by a mixed infection with A. haemolyticum and Streptococcus agalactiae (S. agalactiae) in a patient with diabetes mellitus. A 51-year-old male with poorly controlled diabetes mellitus presented with extensive swelling, necrosis, and bullae formation in his left lower extremity five days after sustaining a puncture wound. Laboratory tests revealed elevated creatine kinase and inflammatory markers, and imaging identified subcutaneous gas. The patient was diagnosed with NF and underwent emergent debridement. Blood and intraoperative tissue cultures grew both A. haemolyticum and S. agalactiae. Despite aggressive surgical management and appropriate antibiotic therapy, the infection progressed, and the patient underwent a below-ankle amputation on hospital day seven and a below-knee amputation on hospital day 29. Antimicrobial therapy was concluded on day 32. This case underscores the potential for A. haemolyticum, particularly in combination with other pathogens such as S. agalactiae, to cause rapidly progressing and life-threatening NF, particularly in patients with underlying risk factors such as poorly controlled diabetes mellitus.