Collaboration is key: Case report of suspected Pseudomonas fluorescens transfusion-associated infection.

Background: We report a case of suspected Pseudomonas fluorescens transfusion-transmitted infection in a 64-year-old female patient with pancreatic adenocarcinoma. The patient developed a biliary obstruction necessitating a drainage catheter, which was complicated by an arterial hemorrhage. Following the transfusion of 1 RBC unit, the patient developed flank pain, chills, and tachycardia.

Study design and methods: The transfusion reaction workup was negative for hemolytic transfusion reaction. However, Gram stains of the implicated RBC unit revealed Gram-negative rods. Fortunately, the patient was already receiving broad-spectrum antibiotics, and preliminary investigation results were available early enough to alert the medical team and adjust antibiotic coverage. The patient was hospitalized in the ICU where she had elevated WBC counts that normalized after the addition of cefepime. The blood collection center was notified.

Results: Both aerobic and anaerobic cultures incubated at 35°C were negative for growth. A subculture and incubation at room temperature (25°C) demonstrated sufficient growth for the identification of Pseudomonas fluorescens by both Vitek-MS MALDI-TOF and Vitek2 biochemical methods.

Discussion: Pseudomonas fluorescens is a Gram-negative rod-shaped bacterium, well-studied as an environmental microbe. It can cause opportunistic infections in humans and was implicated in previous fatal septic transfusion reactions. This report highlights the importance of both standardization in blood product culture protocols and the need for collaboration between microbiology laboratories and transfusion practitioners to optimize the recovery of potentially clinically important fastidious organisms.