Peritonitis is an inflammation of the peritoneal membrane caused by infection, generally bacterial. It remains the most significant complication deriving from the dialysis technique itself.

Shewanella putrefaciens is an oxidase-positive, facultative anaerobic, non-fermenting, Gram-negative bacillus found mainly in marine environments.

It is an uncommon pathogen in human beings, mainly causing skin and soft-tissue infection.1–4

We report a case of S. putrefaciens peritonitis in a 40-year-old woman with Takayasu arteritis and stage 5 chronic kidney disease in automated peritoneal dialysis (PD) since February 2009. In June 2014, she visited the emergency department owing to fever and abdominal pain for the last 12h. Mesenteric ischaemia was ruled out by means of a CT scan. Subsequently, the peritoneal fluid was drained and peritoneal fluid with a cloudy, yellowish appearance was observed. A physical examination revealed diffuse abdominal pain, and an inspection of the catheter outlet revealed no signs of local infection.

A peritoneal fluid count showed 20,160cells with 81% polymorphonuclear cells, and samples were collected for culture.

Blood clinical chemistry showed neutrophilia, normochromic normocytic anaemia and high levels of acute-phase reactants and procalcitonin. She was admitted given her compromised general condition and persistent fever.

Antibiotic therapy was started with intraperitoneal vancomycin and ceftazidime, according to our hospital's protocol.

Multisensitive S. putrefaciens and Klebsiella oxytoca were isolated in a peritoneal fluid culture. Blood cultures were negative.

After identification of the responsible pathogen, treatment with vancomycin was suspended, treatment with intraperitoneal ceftazidime was maintained and oral ciprofloxacin and fluconazole were added.

The patient progressed satisfactorily; she became afebrile and asymptomatic and her laboratory parameters returned to normal. She was discharged and remained in PD.

The Shewanella genus is found throughout numerous geographic areas with moderate climates, mainly in humid environments (saltwater, freshwater and wastewater). However, it is also present in natural energy reserves (petroleum and gas), dairy products, meat and human samples.

It tends to isolate itself by becoming a part of a mixed bacterial flora; therefore, its clinical significance may be obscured by the other microorganisms. It causes various types of syndromes, and is found in patients with infectious endocarditis, bacteraemia, lower limb abscesses, soft-tissue or intra-abdominal infections in patients in PD, pneumonia associated with the use of mechanical ventilation, eye infections and brain abscesses.5

The S. putrefaciens pathogen tends to be sensitive to aminoglycosides, carbapenems, erythromycin and quinolones.

The pathogenesis and the site of entry of the infection remain poorly established. Proximity to seawater or tap water renders these media potential sources of infection.

There are 6 published cases of S. putrefaciens peritonitis in patients in PD – Taiwan, Australia, Israel and the United States5 – with a variety of clinical manifestations, concomitant bacteraemia and, sometimes, a fatal outcome, as in the case of peritonitis with necrotising fasciitis in Korea, the case of peritonitis with spleen abscess from the Australian group, and even other cases with fulminant periorbital – facial cellulitis, biliary tract infection, empyema or perianal abscess. The majority of these patients had factors such as malignant neoplasm, hepatobiliary disease, neutropenia, etc. Renal failure may also represent a risk factor.

The case presented seems to be the first documented case in Spain. After an exhaustive medical history we were unable to identify a clear source of exposure. Our only clue was that the patient had a high level of exposure to seawater.

Whatever the mechanism, it seems wise to warn patients in PD of the importance of properly covering the catheter outlet and any potential site of infection such as ulcers. In addition, although this type of peritonitis is uncommon, a potentially serious cause of peritonitis should be considered and a skin lesion or portal of entry should be heeded as a potential warning, especially in patients with a history of exposure to seawater.