[Diagnostic Approaches in Sepsis - Part 2: Pathogen Detection]

[Diagnostic Approach in Sepsis]

Sepsis occurs both community acquired and as a complication of hospital treatment. The symptoms are usually nonspecific and there is no diagnostic gold standard. The diagnostic differentiation from other clinical pictures is difficult. Therefore, the (early) diagnosis of sepsis is still a major challenge for the clinician. Despite multiple biomarkers described in the scientific literature sepsis is still primarily a clinical diagnosis. qSOFA can be a helpful screening tool.

Finding and treating the focus of infection is a crucial part of sepsis therapy. Chest X-ray and sonography have limited sensitivity for this purpose. A CT-scan with contrast should be done at least in all patients where the focus of infection is still unclear. An MRI is necessary if spondylodiscitis is suspected, a transesophageal echocardiography if endocarditis is a possible focus. Biomarkers are helpful in guiding therapy but are not part of the initial diagnosis criteria. Blood cultures and microbiological samples from the suspected foci of infection should be taken in all sepsis patients. An initial lactate measurement is also part of the diagnostic workup and necessary for the diagnosis of septic shock.

The diagnostic value of next-generation sequencing technology in sepsis

Objective

This study aims to assess the clinical utility of next-generation sequencing (NGS) in sepsis diagnosis.

Methods

A prospective study was conducted on patients with a high suspicion of sepsis by unknown pathogens from January 2017 to December 2021. Blood samples were taken from patients to perform NGS, blood culture (BC), leucocyte (WBC), procalcitonin (PCT), creatinine (CREA), Albumin (ALB) and C-reactive protein (CRP) tests.

Results

The feedback time for BC was 3~5 days for bacteria and 5~7 days for fungi, while the turnover time for NGS was only 24 h. The clinical diagnosis was considered the “gold standard”. 83 patients passed our inclusion criteria and were separated into two groups by clinical diagnosis. 62 met the clinical diagnosis criteria for sepsis and 21 were non-sepsis. The data from the two groups were retrospectively compared and analyzed. Of 62 sepsis in 83 patients, 8(9.64%) were diagnosed by both BC and NGS, 51 (61.45%) by NGS only, 1(1.20%) by BC and 2 (2.41%) by conventional testing only; PCT, CREA, CRP levels and the detection rate of NGS and BC were higher in the sepsis group than in the non-sepsis group, while ALB levels were lower (p<0.05). The logistic regression results in our study revealed that NGS and ALB were independent prediction factors for sepsis (p<0.05), the area under the receiver operating characteristic curve (AUC), sensitivity and specificity of NGS for diagnosing sepsis was 0.857, 95.16% and 76.19%, while ALB was 0.728, 58.06%, 80.95%, respectively. The combination’s sensitivity, specificity and AUC of NGS and ALB were 93.55%, 85.71% and 0.935, greater than that of Albumin or NGS only (both p<0.05).

Conclusion

NGS can effectively and quickly identify pathogens, thereby emerges as a promising technology for sepsis diagnosis. Combination of NGS and ALB can be used for early screening and is more powerful than NGS or ALB only.