171. Gram-Positive Blood Culture Contamination Rates: A Comparative Assessment Between Verigene® and Conventional Method

Abstract

Abstract Background The estimated cost of treatment for septicemia among hospitalized patients is $15.4 billion. Approximately 20%-50% of all positive blood cultures were likely false positives. The rates of the reported contaminations in the literature range from 0.6%-12.5%. The false positive report of bacteremia has significantly impacted overall healthcare by increasing mortality rates, prolonging hospital stays, and expanding the cost of care. The use of Verigene® offers polymerase chain reaction (PCR) amplification in < 5 minutes. In our study, we examine the Verigene®, compared to the standard blood culture by the Vitek-2®, to assess for detecting Gram-positive blood contamination (GPBC). Methods Blood cultures were collected from patients with sepsis in four hospitals in El Paso, Texas (1/1/2018-5/30/2022). Samples were run through Verigene®. Simultaneously, all specimens were cultured using the conventional method and then incubated for five days. Gram stain used for positive samples. Speciation and antimicrobial susceptibility using Vitek-2®. GPBC in Vitek-2® was identified when one set of two grows microorganisms, universally known as skin flora, without clinical sepsis within 48hr. GPBC in Verigene® was identified when it recognized any skin flora without clinical sepsis within 24hr. The analysis was made using McNemar’s Chi-square test. An observation was statistically significant if the p-value was ≤0.05. Results A total of 816 Gram-positive results were obtained. The prevalence of GPBC based on the traditional technique was 98.65% and 64.25% based on the Verigene®. Staphylococcus epidermidis was the most detected at 52%, followed by Staphylococcus aureus at 26%. The sensitivity of the Verigene® for GPBC detection was 64.22%, and the specificity was 33.33%.Figure 1.Frequency of Gram-positive Microorganisms DetectionFigure 2.Sensitivity and Specificity of Verigene® in Identification of Contamination in Gram-positive Blood CultureTable 1.Sensitivity and Specificity of Verigene® in Identification of Contamination in Gram-positive Blood Culture Conclusion The use of Verigene® alone in identifying GPBC is insufficient. Despite the higher sensitivity in detecting microorganisms compared to Vitek-2®, this should be paired with clinical judgment and conventional methods. The ability to recognize GPBC by Verigene® was affected by the lack of clinical evidence to exclude sepsis in the first 24hr. This study is the first to evaluate Verigene® for identifying GPBC. Further interventions should be introduced, i.e., reporting titer by PCR on any detection. Disclosures All Authors: No reported disclosures