The significance of Pseudomonas species other than P.aeruginosa from clinical samples is often questionable. Infections are usually associated with immunocompromised state, endovascular prosthetic devices, or are iatrogenic. Although they have low virulence, they survive harsh environments, and can contaminate medical supplies. Tolerance to antiseptic solutions can lead to pseudobacteraemia. P.stutzeri is an unusual cause of human infection, with bacteraemia more commonly associated with contaminated dialysis fluid (1).
A 91 year old gentleman was admitted with severe skin and soft tissue infection of his left leg following a laceration whist sailing on the Swan River. He cleaned and dressed the wound himself, using old antiseptic liquid. He developed wound infection and was prescribed cephalexin by his GP with initial improvement, but attended ED with worsening swelling. CRP was 340mg/L with neutrophilia of 13.4 x 109/L. He was commenced on IV flucloxacillin. Inflammatory markers remained elevated and vancomycin was added. Two days into admission the aerobic bottles of both sets of blood cultures grew Pseudomonas stutzeri (MALDI-TOF score >2.0). A wound swab subsequently had abundant growth of the same, although not seen on gram stain. In light of his failure to improve, after two additional sets of blood cultures were taken antimicrobial therapy was changed to cefepime.
He clinically and biochemically improved following switch to cefepime, and was subsequently changed to oral ciprofloxacin to complete 3 weeks total. The aerobic bottles of both of the second sets grew P.stutzeri, confirming true bacteraemia. There was no evidence of immune compromise bar senescence due to age. Old antiseptic solution is a possible source of his infection, as is the environment of his initial injury.