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Necrotizing Fasciitis Following Marine Water Exposure Caused by Shewanella Putrefaciens
Mahdis Solhjoo1, Uzma Malik1, Tabassum Yasmin2. 1Medicine, Nassau University Medical Center, Westbury, New York, United States, 2Infectious Disease, Nassau University Medical Center, East Meadow, New York, United States

Purpose of Study Shewanella putrefaciens is a gram-negative bacillus which is found as a microflora of marine environments. In rare cases it can be a human pathogen which usually occurs in the patients with underlying disease. Shewanella putrefaciens usually causes the soft tissue infections including leg ulcer and cellulitis. We aim to expand understanding of this rare disease and its effective management.
Methods Used No method
Summary of Results A 65 year old male with the past medical history of multiple sclerosis, presented with leg swelling and pain. Patient had few scratches on his foot after having a mild leg injury. He went to the bay few days after the injury and started to have swelling and pain in the injured foot. In physical exam, cellulitis changes with hemorrhagic blisters was noticed over the left hallux and foot. X-ray of the left foot demonstrated soft tissue swelling. Patient started on Vancomycin and Piperacillin/Tazobactam in the setting of cellulitis. Blood and wound culture became positive for Shewanella putrefaciens. Biopsy report after second tissue debridement revealed necrotizing inflammation and abscess formation. Magnetic resonance imaging (MRI) of foot showed cellulitis and myositis with no evidence of osteomyelitis. After few weeks of antibiotic therapy, the repeated wound and blood culture was still positive for Shewanella putrefaciens, therefore Amikacin added as the second coverage. The repeated MRI showed early osteomyelitis associated with the proximal phalanx of the great toe but it was considered as reactive osteitis secondary to multiple debridement. Treatment continued for another 4 weeks and the repeated blood and wound culture became negative. Patient continued receiving hyperbaric oxygen therapy and skin grafts with significant improvement.
Conclusions Underlying chronic disease increases the occurrence of the infection and is usually associated with poorer prognosis. Immunocompromised patients are also prone to primary bacteremia with fulminant course. In this study, the only underlying disease in the patient medical history is MS which might increase the risk of Shewanella infection in our patient. To our knowledge this is the first case of Shewanella infection in a patient with chronic neurologic condition such as MS.

Fig 1: Cellulitis changes with hemorrhagic blisters over the patient's left hallux and foot secondary to Shewanella putrefaciens infection.

Fig 2: Patient's foot after extensive debridement.

Fig 3: Colonies of Shewanella putrefaciens from the wound of the patient.

Fig 4: Shewanella putrefaciens under microscopy.

Fig 5: Patient's foot after antibiotic therapy for Shewanella putrefaciens and skin grafts

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