Shewanella putrefaciens, an emerging foe from climate change: a case report

Shewanella putrefaciens is a Gram negative, facultatively anerobic bacterium commonly found in aquatic environments and is associated with decomposing organic matter. Although typically nonpathogenic, it has been recognized as an opportunistic pathogen capable of causing rare infections in humans, particularly immunocompromised individuals or those with underlying health conditions.

We report the case of a 74-year-old white Italian female who developed a soft tissue infection after sustaining a leg injury and subsequently bathing in the coastal waters of Valencia, Spain. Despite initial treatment with amoxicillin/clavulanic acid and wound debridement, the infection persisted. Microbiological analysis revealed the presence of Shewanella putrefaciens and Bacteroides fragilis. The patient required a second-line antibiotic regimen with ciprofloxacin, which successfully resolved the infection, although the patient experienced chronic ankle edema owing to underlying lymphatic insufficiency.

This case underscores several critical considerations: the emerging pathogenic potential of S. putrefaciens, the implications of environmental antibiotic resistance, and the increased risk of such infections in the context of global warming and rising sea temperatures. With climate change contributing to warmer aquatic environments, the proliferation of marine bacteria, such as S. putrefaciens, may lead to a growing number of opportunistic infections, emphasizing the need for vigilance in both clinical and environmental health settings.