Aeromonas hydrophila Necrotizing Soft-Tissue Infection With Acute-on-Chronic Calcaneal Osteomyelitis Following Freshwater Exposure in a Patient With Poorly Controlled Diabetes Mellitus.

Aeromonas hydrophila is a gram-negative bacterium found in freshwater environments that can cause rapidly progressive necrotizing soft-tissue infections (NSTIs), particularly in patients with predisposing host factors such as diabetes mellitus. The organism rarely affects deeper structures such as bone, which can make diagnosis and treatment more difficult. We report the case of a 68-year-old man with poorly controlled type 2 diabetes mellitus, heart failure with reduced ejection fraction, and prior calcaneal trauma who developed an NSTI with acute-on-chronic calcaneal osteomyelitis after stagnant rainwater entered a closed shoe. Symptoms began later that day and progressed over the next five days, culminating in a limb-threatening infection with sepsis documented by the treating teams and requiring urgent surgical intervention. Operative abscess cultures obtained during incision and drainage grew A. hydrophila complex, while calcaneal bone biopsy demonstrated osteonecrosis with acute osteomyelitis; the pathology report also listed a methicillin-resistant Staphylococcus aureus marker. The patient was managed with surgical debridement and antimicrobial therapy directed by Infectious Diseases, ultimately receiving intravenous ceftriaxone and levofloxacin to complete a six-week course. This case underscores the importance of considering environmental exposures, obtaining early surgical consultation, and using operative microbiology and pathology to guide management of rapidly progressive soft-tissue infections.