Case Study 1

In a study conducted by Lee Health System clinicians at Lee Memorial Hospital, Fort Myers, Florida, T2Bacteria® Panel research use only (RUO) results were compared to conventional standard of care culture results. This comparison allows an analysis of how the use of the T2Bacteria Panel could have potentially changed clinical practice and outcomes.

Page Title: Suspected Intra-abdominal sepsis

Sub-Header: Patient presents with suspected sepsis.

Presentation: 53-year-old immunocompromised, morbidly obese female with recent history of surgery to drain an intra-abdominal abscess. Patient presented at the emergency department 8 days post-op with fever, chills and abdominal pain. Sepsis was suspected and patient was admitted with orders for blood cultures, T2Bacteria and broad spectrum antibiotics.

Patient Selection Criteria

SIRS criteria:

  • Temperature- 103.4
  • Heart Rate-133 BP90/62
  • Respiratory Rate – 34
  • WBC: 6,800/mm3

NEWS Score: 9

QSOFA Score – 2

Evaluation and Treatment Decision

Diagnosis: Suspected Intra-abdominal sepsis

Empiric Therapy: Linezolid, Aztreonam, Metronidazole

Linezolid was chosen for gram-positive coverage due to challenges with vancomycin dosing in obese patients. Aztreonam was chosen for gram-negative coverage due to patient history of penicillin allergy. Metronidazole was chosen for anaerobic coverage.

T2Bacteria Result: Positive for E. coli and P. aeruginosa and negative for S. aureus, E. faecium, and K. pneumoniae. (SA -, PA + & EC +); T2Bacteria results were not reported as this case was part of an observational study.  

Blood Culture Result: Negative

Decision making based on T2Bacteria Result:

The negative S. aureus result meant that the patient did not have MRSA and therefore linezolid could have been discontinued after the first dose when the T2Bacteria result was available, a 4.5 day reduction in linezolid. The patient’s therapy could have been more targeted gram-negative coverage by switching to meropenem to cover E. coli and P. aeruginosa

Discussion:

Upon admission, the patient was initially given the broad spectrum antibiotics linezolid, aztreonam and metronidazole for the treatment of suspected intra-abdominal sepsis. Due to the patient’s recent healthcare exposure, she was at risk for organisms such as MRSA (methicillin resistant Staphylococcus aureus) and Pseudomonas aeruginosa in addition to the more common causes of intra-abdominal infection such as enterobacteriaceae and anaerobic organisms.

At the time of admission, she had blood cultures obtained and T2Bacteria ordered. At Lee Health patient selection for T2Bacteria testing was based on the NEWS (National Early Warning Score) scoring system. The NEWS score was developed to standardize the approach to detection of clinical deterioration in acutely ill patients in the United Kingdom, and a score of 7 or higher puts the patient in the high risk category. This patient also was positive for 3 of 4 SIRS criteria and had a qSOFA score of 2 indicating a high risk of mortality.

Due to the negative blood culture (T2Bacteria results were not reported as this case was part of an observational study), the patient remained on empiric therapy for 5 days and then was changed to oral therapy and discharged 2 days later. Had the T2Bacteria result been reported, the patient could have been changed to meropenem to cover the E. coli and P. aeruginosa, allowing discontinuation of aztreonam. Given the S. aureus was negative, linezolid could have been discontinued as well. Discontinuation of these two antibiotics within the first 24 hours of admission would have led to ~$6,000 savings in antibiotic charges, and potentially led to earlier discharge on effective oral therapy.