Point-of-Care Test for Septic Effusions in Dogs & Cats

In the Literature

Vezzi NK, Lane SL, Thevelein BA, Brainard BM. Performance evaluation of a Test&Treat rapid detection kit for the diagnosis of septic effusions in dogs and cats. J Vet Emerg Crit Care (San Antonio). 2024;34(2):110-115. doi:10.1111/vec.13372

The Research …

Bacterial sepsis is a life-threatening condition with high morbidity and mortality rates. Rapid diagnosis is crucial because survival is correlated with speed of therapeutic intervention.^1-3 Aerobic and anaerobic culture is the gold standard for diagnosis, but prolonged time needed to obtain results may delay intervention. Point-of-care (POC) tests for rapid diagnosis of sepsis include microscopic cytologic analysis of toxic neutrophils and bacteria, total nucleated cell count, and paired glucose evaluation.^4,5

In this study,^a a proprietary POC diagnostic test that uses bioluminescent reagents to identify bacterial adenosine triphosphate (ATP) was evaluated for utility in rapid diagnosis of septic effusions in dogs and cats. The test reportedly has high sensitivity and specificity for diagnosis of canine UTIs.⁶ Dogs (n = 40) and cats (n = 8) with nonhemorrhagic pleural and/or peritoneal effusion were enrolled, and 50 samples underwent culture, bioluminescent testing with the POC test, and standard diagnostic testing. Half of each sample was passed through a 10-µm syringe filter prior to incubation in a proprietary mixture of culture broth and detergent, as researchers hypothesized the higher cell count in septic pleural and peritoneal effusions compared with urine may yield false-positive results. Bioluminescence of bacterial ATP was measured via a luminometer and recorded as relative light units (RLUs).

Based on positive culture results (primary determinant for septic fluid classification), 42% of samples were septic. Both filtered and unfiltered septic effusion samples exhibited higher nucleated cell counts and median RLUs compared with nonseptic effusions. Median RLUs of unfiltered samples were higher than those of filtered samples. A 30-minute incubation time using filtered samples with an optimal RLU cutoff of >12,202 yielded the highest sensitivity (81%) and specificity (82%) for identification of septic effusions. The authors concluded bioluminescent testing may be a useful screening tool when used in conjunction with other diagnostic testing to support diagnosis of septic effusion.

^a Test&Treat (now Load&Go) provided the reagents and analyzers used in this study but did not provide additional input on study design or data analysis.

… The Takeaways

Key pearls to put into practice:

• Broad-spectrum IV antibiotics should be administered early in all cases of confirmed sepsis, as well as in cases with high suspicion for sepsis following blood, urine, and/or effusion sample collection.

• Culture is recommended for samples suspected to be septic to facilitate bacterial identification and susceptibility testing; however, prolonged time needed to obtain results precludes utility of culture in rapid diagnosis and may delay therapeutic intervention. POC tests (eg, cytology to identify intra- and extracellular bacteria and toxic neutrophils, total nucleated cell count, paired glucose evaluation) should be used while culture results are pending.

• Septic peritonitis and pleuritis warrant an aggressive and often invasive therapeutic approach and have guarded prognoses. Multiple diagnostic tests should thus be used to confirm diagnosis due to the risk for false-positive and false-negative test results.