High Negative Predictive Value Enables De-escalation of Therapy

A 72 year-old-patient presented to the ER with productive cough for three days, left flank pain, and intermittent nausea

Discussion

This case highlights the benefits of using the high negative predictive value (NPV) of the T2Bacteria Panel for early de-escalation of therapy, mainly when using antimicrobial agents that can commonly cause acute kidney injury.

Presentation

A 72 year-old-patient presented to the ER with productive cough for three days, left flank pain, and intermittent nausea.  Pertinent laboratory values included a temperature of 38.5 oC, WBC of 18.5, and a lactic acid of 5.4. The patient was hospitalized one month prior for nephrolithiasis with left ureteropelvic junction (UPJ) obstruction, complicated by ESBL E. coli bacteremia, and had a left ureteral stent placed at the time. A urinalysis, urine culture, blood culture, and T2Bacteria sample were drawn in the ER, and the patient was started on meropenem and vancomycin due to recent surgery and history of ESBL E.coli infection. The patient was transferred to the ICU.

Patient Selection Criteria

Septic patient with a fever presenting to the ED

Evaluation and Treatment Decision

Empiric Therapy: Patient was started on meropenem and vancomycin

T2Bacteria Panel Result: Positive for E.coli, negative for S. aureus, P. aeruginosa, K. pneumoniae, E. faecium

Blood culture Result: Positive for E.coli (ESBL positive)

Urine culture Result: Positive for E.coli (ESBL positive)

Hospital course and decision making based on the T2Bacteria Result

The positive T2Bacteria result for E. coli came back once the patient was transferred to the ICU. The team discontinued vancomycin based on the negative T2Bacteria result for S. aureus and continued the meropenem.  The high NPV (99.7%) of the T2Bacteria Panel provided crucial diagnostic information that allowed for more informed treatment decisions, specifically the de-escalation of the anti-staphylococcal agent.  Blood and urine cultures resulted on the third day of therapy, both positive for ESBL E. coli, sensitive to meropenem.  The patient was continued on meropenem and discharged to subacute rehab with a plan to continue meropenem until their scheduled ureteral stent removal and replacement.

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  • According to the CDC, of the 154 million prescriptions for antibiotics written in doctors' offices and emergency departments each year, 30% are unnecessary.12