Emerging Infections Due to Shewanella spp.: A Case Series of 128 Cases Over 10 Years

Abstract

BackgroundShewanella species are emerging pathogens that can cause severe hepatobiliary, skin and soft tissue, gastrointestinal, respiratory infections, and bacteremia. Here we reported the largest case series of infections caused by Shewanella species.AimTo identify the clinical features and risk factors predisposing to Shewanella infections. To evaluate resistance pattern of Shewanella species and appropriateness of antibiotic use in the study cohort.MethodsPatients admitted to a regional hospital in Hong Kong with Shewanella species infection from April 1, 2010 to December 31, 2020 were included. Demographics, antibiotics, microbiology, and outcomes were retrospectively analyzed.FindingsOver the 10 years, we identified 128 patients with Shewanella species infection. 61.7% were male with a median age of 78 (IQR 65–87). Important underlying diseases included hepatobiliary diseases (63.3%), malignancy (26.6%), chronic kidney disease or end-stage renal failure (25.8%), and diabetes mellitus (22.7%). Hepatobiliary infections (60.4%) were the most common clinical manifestation. Majority (92.2%) were infected with Shewanella algae, while 7.8% were infected with Shewanella putrefaciens. The identified organisms were usually susceptible to ceftazidime (98.7%), gentamicin (97.4%), cefoperazone-sulbactam (93.5%) and ciprofloxacin (90.3%). Imipenem-susceptible strains were only present in 76.6% of isolates.ConclusionThis largest case series suggested that Shewanella infections are commonly associated with underlying comorbidities, especially with hepatobiliary diseases and malignancy. Although Shewanella species remained largely susceptible to third and fourth generation cephalosporins and aminoglycosides, carbapenem resistance has been on a significant rise.

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

“…Looking at the most extensive study to date, S. algae was isolated from 118 patients with associated risk factors, including the following: hepatobiliary diseases, malignancy, chronic kidney disease, and diabetes mellitus [6]. Other risk factors described in the literature include male sex [11], immunodeficiency, and chronic ulcerations on the lower limbs [5][6][7][8][9][10][11][12].…”

“…Most clinically relevant infections include otitis media, skin and soft tissue infections (usually following local trauma or ulceration), invasive diseases (usually uncomplicated bacteraemia), and hepatobiliary diseases [5][6][7]. Other infections, though rarely described, have been identified, including some with a fulminant course [14].…”

“…S. algae was identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Although this technique has some limitations in identifying Shewanella at the species level due to an incomplete database [5][6][7][8][9], new efforts to create a new database have produced promising results [10]. Susceptibility testing was not performed on any of the isolates.…”

“…It is a ubiquitous microorganism usually found in seawater, freshwater, and soil, capable of survival under suboptimal environmental conditions [1][2][3]. Although more than 70 species of Shewanella have been identified, only S. algae, S. putrefaciens, and S. xiamenensis have been associated with human disease, with S. algae comprising most cases [4][5][6].…”

“…Traditionally associated with warmer climates, S. algae has now been isolated from patients worldwide (including Europe and North America) [1,7], and is considered an emerging human pathogen [6][7][8]. In this paper, we present a series of four patients infected with S. algae, detected over the past 10 years at a regional hospital on the outskirts of Lisbon.…”