MIKROBIYOLOJI BULTENI, vol.46, no.1, pp.117-121, 2012 (SCI-Expanded)
Shewanella putrefaciens is a gram-negative, non-fermentative, oxidase positive, motile bacillus that produces hydrogen sulphide. It is found widely in the nature especially in marine environments. Although it is accepted as saprophytic, different clinical syndromes, most commonly skin or soft tissue infections, have been associated with S.putrefaciens, mainly in immunocompromised cases and patients with underlying diseases. However, pneumonia cases due to S.putrefaciens are quite limited in the literature. In this report, a case of pneumonia caused by S.putrefaciens was presented. A 43-year-old female patient was admitted to our hospital with the complaints of fever, cough, sputum and weakness. The patient has had brochiectasis since childhood and has used periodical antibiotic therapies due to pneumoniae episodes. She was diagnosed to have pneumonia based on the clinical, radiological and laboratory findings, and empirical antibiotic treatment with ciprofloxacin and ceftazidime combination was initiated. Gram-stained smear of sputum yielded abundant leucocytes and gram-negative bacteria, and the isolate grown in the sputum culture was identified as S.putrefaciens by conventional methods and API 20 NE (BioMerieux, France) system. The isolate was found susceptible to ceftriaxone, ceftazidime, cefepime, ciprofloxacin, piperacillin-tazobactam, cephoperazon-sulbactam, imipenem, amikacin, gentamicin and trimethoprime-sulphametoxazole; whereas resistant to ampicillin, amoxycillin-clavulanate, cefazolin and cefuroxime, by Kirby-Bauer disk diffusion method. According to the antibiogram results, the therapy was changed to ceftriaxone (1 x 2 g, intravenous). The patient was discharged with complete cure after 14 days of therapy. In conclusion, S.putrefaciens should be considered in patients with predisposing factors as an unusual cause of pneumonia and the characteristics such as H2S production and sensitivity to third generation cephalosporins and penicillins should be used to differentiate it from Pseudomonas aeruginosa and prevent the unnecessary use of antipseudomonal antibiotics.