Page 21 - JSOM Winter 2019

Severe Lower Body Swelling and
Bacteremia Secondary to Shewanella algae Bacteremia
During Basic Underwater Demolition SEAL Training

Rachel E. Bridwell, MD*; Brandon M. Carius, MPAS, PA-C; Joshua J. Oliver, MD

ABSTRACT
Shewanella algae is a unique bacterium largely documented most involve cellulitis; the lower extremities tend to have the
in skin and soft tissue infections (SSTIs) with a wide range highest rates of seawater contact and have high exposure rates
of presentations from gas-producing necrotizing fasciitis to of peripheral vascular disease–induced ulcers as the likely site
osteomyelitis. Seawater exposure to lower extremity ulcers of infection. In a case series of 27 individuals with S algae–
6,9
and wounds is most often correlated with infection, which has based SSTIs, 51.9% had chronic ulcers of the lower extrem-
been documented in causing complications of bacteremia, sep- ity. Inoculated ulcers risk hematogenous seeding onto heart
1
sis, and infective endocarditis. Further complicating treatment valves, resulting in fatal endocarditis. 10,11 Musculoskeletal
is poor response to most empiric regimens prior to definitive complications of S algae infections range from osteomyelitis to
diagnosis and an uneven response to antibiotics, including flexor tenosynovitis from injuries as simple as saltwater fish-
documented resistance to carbapenem. This case documents hook puncture. 6,8,12 A series of 53 cases of otitis media and
the presentation of a Basic Underwater Demolition SEAL otitis externa from seawater exposure was found in Denmark,
(BUD/S) training candidate who presented acutely for com- including one complicated by intracerebral abscess. 6,8
plaints of severe lower body swelling and abrasions during
“Hell Week” and was found to have polymicrobial bacteremia Complex presentations of S algae center primarily on the
with Staphylococcus aureus, Enterococcus, and S algae. hepatobiliary and gastrointestinal (GI) systems, with result-
ing cholecystitis, peritonitis, abdominal abscess, and GI-based
Keywords: Shewanella algae; bacteremia; military training, bacteremia. 6,13 Conversely, there are cases of simple-appearing
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underwater gastritis with infectious diarrhea. Given this nonspecific pre-
sentation, these cases are often mistaken for more common
bacteria, resulting in misguided antibiotic administration and
morbidity. 5,14
Introduction
S algae was first discovered in 1990 but was grouped under Similar to this case, a variety of case series have found rates
the genus member S putrefaciens until it distinguished as a new of S algae polymicrobial infections to be as high as 50% to
4,6
1,2
bacterial species in 1992. These bacteria are both known for 81%. The most common coinfecting bacteria in these cases
severe infections with the production of subcutaneous hydro- were Enterobacteria, but other polymicrobial species in-
2,3
gen sulfide gas. Much of the literature acknowledges that cluded Staphylococcus spp, Aeromonas spp, Escherichia coli,
most cases of S algae are still likely misclassified as S putre- Pseudomonas spp, and Klebsiella spp, with as many as four
faciens, and therefore distinguishing true S algae reference total organisms isolated from a single sample. 1,3,4,6 The com-
cases is difficult despite recognition of S algae’s predominance. plicated polymicrobial nature of these infections, along with
4
Given its virulence, presentation, and relative obscurity, S algae nonspecific presentation, can delay optimal antimicrobial
is often mistaken for Pseudomonas aeruginosa, Aeromonas hy- management while awaiting bacterial cultures. Unfortunately,
drophilas, or Vibrio vulnificus. Similarly, like V vulnificus, S previous cases have shown inconsistent clinical resolution
5,6
algae is most often found in marine environments, and patients with empiric treatment, usually with ceftriaxone, doxycycline,
are most often inoculated through saltwater exposure, amplify- and ciprofloxacin. 1,3,15 Some S algae isolates demonstrate quin-
ing the misidentification as Vibrio and triggering inappropriate olone resistance, and additional strains have been found to
4,5
empiric treatment based on presentation and history. Most have resistance to penicillin, cefazolin, and even carbapen-
cases and series detail exposure in warm climates of the Carib- ems. 15–18 This substantially narrows viable treatment options
bean Sea, Indian subcontinent, and Persian Gulf, but there have toward third- and fourth-generation cephalosporins, limiting
also been cases of S algae reported in waters as cold as 13°C antibiotic options. Surgical washout or debridement may be
(55°F) off the Danish coast in the North and Baltic Seas. 6–8 indicated depending on the mechanism of injury, location, and
distribution of infection. 12
Although case reports and small case series form most of the
S algae literature, the types and presentations of infection are S algae has often been implicated in infections of immunocom-
broad. SSTIs form the basis of most reports and series, and promised populations, with implications in assessing the risk
*Correspondence to Rachel E. Bridwell, MD, 3551 Roger Brooke Dr, SAUSHEC Emergency Medicine Department, Fort Sam Houston, TX
78234-6200 or r.e.bridwell@gmail.com
CPT Bridwell, MC, USA, CPT Carius, SP, USA, and CPT Oliver are affiliated with the SAUSHEC Emergency Medicine Department, Fort Sam
Houston, TX.

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