Shewanella algae, an Emerging Human Pathogen: A Series of Four Cases From a Portuguese Hospital

Abstract

Shewanella algae is a rod-shaped, Gram-negative bacterium that is considered an emerging human pathogen. Traditionally associated with warmer climates, S. algae has now been isolated from patients worldwide, and reports of infection are increasing. In a regional hospital on the outskirts of Lisbon, Portugal, four cases have been detected in the past 10 years. Two of the patients were migrants from African countries with daily contact with water; the other two patients were Portuguese, and no epidemiological risk factors were found among them. These are the first cases reported in Portugal. Risk factors associated with S. algae infection in patients discussed in this paper include the following: human immunodeficiency virus (HIV) infection, chronic venous insufficiency, lower limb ulcers, chronic kidney disease, diabetes, arterial hypertension, dilated cardiomyopathy, atrial fibrillation, chronic hepatic disease, and chronic pancreatitis. One patient died in the intensive care unit with septic shock and disseminated intravascular coagulation from a fulminant infection secondary to S. algae bacteraemia. The four clinical cases presented in this case series highlight the clinical features of this infection so that other physicians can successfully identify and treat S. algae infections.

Severe Shewanella Cellulitis Following Saltwater Exposure in an Elderly Patient

“…Shewanella algae, a Gram-negative bacillus traditionally found in marine settings, is increasingly recognized as a versatile and opportunistic pathogen. This microbe's ability to inflict a wide array of human infections-from superficial soft tissue afflictions to more critical conditions like bacteremia, otitis, and hepatobiliary infections-highlights its clinical relevance [1]. Despite their relative rarity, the infections they cause are noteworthy for their potential to escalate into severe complications, including sepsis and tissue necrosis [1].…”

“…This microbe's ability to inflict a wide array of human infections-from superficial soft tissue afflictions to more critical conditions like bacteremia, otitis, and hepatobiliary infections-highlights its clinical relevance [1]. Despite their relative rarity, the infections they cause are noteworthy for their potential to escalate into severe complications, including sepsis and tissue necrosis [1]. This is starkly illustrated in the case of an 88-year-old patient, who, after a seemingly minor blue crab pinch and subsequent exposure to saltwater, developed severe cellulitis.…”

“…The incident rapidly evolved into a grave infection marked by cellulitis, sepsis, delirium, and atrial fibrillation, thereby showcasing the pathogen's virulence and its capacity for diverse and severe clinical manifestations, which notably depart from the generally milder symptoms traditionally linked with Shewanella infections. Shewanella algae's status as a significant emerging pathogen is further substantiated by the surge in reported cases across various geographic regions, including temperate zones such as Portugal [1]. A regional hospital on Lisbon's periphery documented four such instances over a decade, revealing the pathogen's expanding territorial presence.…”

“…A regional hospital on Lisbon's periphery documented four such instances over a decade, revealing the pathogen's expanding territorial presence. The array of risk factors in these patients -encompassing HIV infection, chronic venous insufficiency, and other comorbidities -underscores the bacterium's predilection for individuals with compromised health [1]. Particularly poignant is the case of a patient whose S. algae bacteremia escalated to septic shock and disseminated intravascular coagulation, underscoring the infection's potential severity [1].…”