DVM Ghent University merelbeke, Oost-Vlaanderen, Belgium
Abstract:
Background: Sepsis is a life-threatening condition for which critically important antimicrobials are often indicated. The value of blood culture for sepsis is indisputable, but appropriate sampling guidelines are lacking in calves.
Objectives: To compare diagnostic accuracy and time to positivity (TTP) of two blood culture media (pediatric plus (PP) and plus aerobic (PA)), with a different volume (3 vs. 10 mL) and composition. To estimate blood culture contamination in calves.
Animals: 126 critically ill calves.
Methods: Diagnostic test study in which performance of PP, PA, and hypoglycemia (< 60mg/dL) was assessed to detect sepsis using a Bayesian latent class model. Survival analysis was used to compare TTP. Contamination was descriptively analyzed. Pathogens were considered relevant when; (1) member of the Enterobacteriaceae family, (2) highly relevant in other bovine pathologies, or (3) isolated from both blood cultures.
Results: The sensitivities for PP, PA, and hypoglycemia were 68.7% (95% credibility interval = 30.5-93.7%), 87.5% (47.0-99.5%) and 61.3% (49.7-72.4), respectively. Specificity was estimated at 95.1% (82.2-99.7%), 94.2% (80.7-99.7%) and 72.4% (64.6-79.6%). No significant difference in TTP was identified between PP and PA. An overall contamination rate of 8.3% (21/252) was assumed, and blood culture positivity reduced (40.5% to 22.2%) when presumed contaminants were excluded.
Conclusions and clinical importance: The PA culture seems to have the highest diagnostic test accuracy compared to PP and hypoglycemia, and the type of culture did not influence TTP or the contamination rate. Therefore, sampling PA culture twice is theoretically the best option to determine sepsis in critically ill calves.
