Title

A rare cause of bacteremia: Shewanella algae

Authors

Sandeep Verma, MD, Franco Murillo Chavez, MD,  Nivedita Kharkongor Chengappa, MD,  Sushrutha Sridhar, MD,  Sanchit Duhan, MD,  Stephan Hambaz, MD.

Introduction

Bacteremia due to gram-negative bacteria is a significant problem in both hospitalized and community-dwelling patients. The incidence of multidrug resistance is on the rise and pose a serious therapeutic problem. Gram-negative bacillary sepsis with shock has a high mortality rate of 12 to 38 percent; depending, in part, on whether the patient receives timely and appropriate antibiotic therapy. Shewanella spp. are saprophytic, gram negative, motile bacilli, commonly found in marine habitat. These bacteria were not considered to be pathogenic historically, until recently when a few case studies of Shewanella algae infection were reported.

Case Presentation

We present a case of an 81-year-old Female, with a past medical history of Heart Failure complicated with Elephantiasis nostras verrucose (ENV), COPD, Diabetes mellitus, chronic kidney disease and Psoriasis, who presented to our institution with acute on chronic severe pain in her legs. The patient had several admissions to different institutions due to her chronic ENV. She complained of intermittent blisters on her legs with chronic drainage of serous fluid, the patient also self-reported frequent wrapping of her legs with garbage bags due to a large amount of secretion. She progressively became bedbound due to the severity of the swelling and pain. Upon admission to our institution, she was found to be critically ill with septic shock which upon further workup was diagnosed as Shewanella algae bacteremia, concomitant Klebsiella pneumoniae urinary tract infection, and L5-S1 osteomyelitis on imaging.

The patient was admitted to the ICU where she was managed with intravenous fluids, norepinephrine, steroids, and iv cefepime for gram positive and gram-negative coverage as well as iv vancomycin initially for possible MRSA coverage. Further workup for the shock revealed leukocytosis, elevated lactate, blood cultures growing Shewanella algae and urine cultures growing Klebsiella pneumonia. In light of cultures, vancomycin was discontinued and cefepime was switched to iv piperacillin-tazobactam based on infectious disease recommendations. Subsequent blood cultures were negative. Patient continued to improve and was transferred out of the ICU to acute care with resolution of symptoms and was eventually discharged with a plan to complete 6 weeks of antibiotics for management of her Shewanella bacteremia and osteomyelitis..

Discussion

Shewanella algae is a exceedingly rare cause of bacteremia, however there are identified risk factors including presence of cutaneous ulcers, exposure to marine environments, hepatobiliary disease and immunocompromised states. Bacteremia is uncommon but has been reported in association with infections of skin and soft tissue, and intra-abdominal or respiratory infections.

Shewanella algae is resistant to first and second generation cephalosporins and penicillins and is sensitive to carbapenems, aminoglycosides, fluoroquinolones, and third and fourth generation cephalosporins. Resistance to carbapenem has being reported recently. Our patient had recurrent cellulitis of her lower extremities and usage of garbage bags to cover her wounds might be an underlying cause of her Shewanella sepsis. Patients presenting with chronic open wounds or any risk factors discussed here should be worked up with high suspicion for Shewanella algae. With increasing incidence of this rare pathogen and emergence of drug resistance, further research for appropriate antimicrobials is warranted.

References

N/A