Case Study 3

The retrospective approach from a study at Northwestern University Feinberg School of Medicine provided an ideal opportunity for detailed case studies, comparing the results using the available standard of care at the time (culture on blood, urine and BAL samples) against more sensitive testing, the T2Bacteria® Panel RUO, five years later. This comparison allows an analysis of how the use of the T2Bacteria Panel could have potentially changed clinical practice and outcomes.

73-year-old female with lymphoma in hospital on chemotherapy and diagnosed with pneumonia and septic shock

Day 1: The blood culture tested positive for Pseudomonas aeruginosa. The patient was given cefepime and ciprofloxacin.

  • Subsequent blood cultures were negative, but the patient deteriorated, developed septic shock, and required intubation.

Day 17: The patient’s bronchoalveolar lavage (BAL) cultures showed 100 CFU/mL Achromobacter and 100 CFU/mL Pseudomonas aeruginosa, below the threshold for clinically relevant titer level of 10,000 CFU/mL set by the laboratory. The results were not alarming, and the antibiotic regimen was not changed.

  • T2Bacteria Panel RUO identified Pseudomonas aeruginosa from blood drawn on day 17
  • Blood culture drawn on day 17 was negative

Day 20: The BAL cultures grew significantly to 100,000 CFU/mL Achromobacter and 100,000 CFU/mL Pseudomonas aeruginosa.

Day 23: The patient expired under palliative care.

Analysis: The T2Bacteria Panel RUO’s identification of Pseudomonas aeruginosa 3 days earlier than the BAL cultures and in the absence of positive blood cultures likely indicates the progression of an infection due to both ineffective source control and inappropriate antimicrobial therapy. The T2Bacteria Panel RUO result may have led to faster targeted therapy, such as the addition of an aminoglycoside to better treat this patient’s septic shock, potentially impacting the outcome.