Department of Medical Microbiology and Infection Control, Amsterdam University Medical Centers, Amsterdam, The Netherlands.
Department of Medical Microbiology, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, The Netherlands.
PLoS One. 2022 Apr 20;17(4):e0266869. doi: 10.1371/journal.pone.0266869. eCollection 2022.
Determination of pathogen-specific bacterial DNA load (BDL) in blood has been shown to be directly correlated with severity of infection in patients with bacteremia. In the diagnostic work-up of patients with Staphylococcus aureus bacteremia (SAB), determination of the primary focus is imperative, because of implications for treatment duration, and ultimately prognosis. Here we investigate whether measurement of BDL in patients with SAB can distinguish between intravascular and extravascular foci of infection.
In a consecutive cohort of 43 patients with positive blood cultures with Staphylococcus aureus, we performed a quantitative PCR on whole blood to detect the bacterial DNA load. Infections were classified into 3 categories: i) soft tissue infections and phlebitis, ii) deep-seated infections and iii) endocarditis and other intravascular infections. Bacterial DNA loads and inflammatory parameters in the three categories were analyzed and compared.
Median BDL in patients with endocarditis and other intravascular infections was 1015 cfu/ml, significantly higher than BDL in the other two categories (28 and 31 cfu/ml respectively). In contrast, CRP and leukocytes were not significantly different between the three patient categories. BDL could be detected in all patients with intravascular causes and levels were generally 10-30 times higher than in the other infection categories. Median BDL in non-survivors was 85 cfu/ml, which was higher than in survivors with a median BDL of 29 cfu/ml, although not significant.
In Staphylococcus aureus bacteremia pathogen-specific BDL is distinctly higher in patients with intravascular infections compared to extravascular origins. As measurement of BDL by PCR can easily be implemented in routine diagnostics, it can improve the diagnostic work-up of SAB by rapidly identifying the subset of patients who need higher dosages of antibiotics and additional measures to improve outcome.
血液中病原体特异性细菌 DNA 载量（BDL）的测定已被证明与菌血症患者感染的严重程度直接相关。在金黄色葡萄球菌菌血症（SAB）患者的诊断中，确定原发性病灶至关重要，因为这涉及治疗持续时间，最终影响预后。在这里，我们研究了 SAB 患者 BDL 的测定是否可以区分血管内和血管外感染灶。
我们对 43 例金黄色葡萄球菌阳性血培养患者进行了连续队列研究，对全血进行了定量 PCR 检测，以检测细菌 DNA 载量。将感染分为 3 类：i）软组织感染和静脉炎，ii）深部感染和 iii）心内膜炎和其他血管内感染。分析和比较了这 3 类感染患者的 BDL 和炎症参数。
心内膜炎和其他血管内感染患者的 BDL 中位数为 1015 cfu/ml，明显高于其他两类患者（分别为 28 和 31 cfu/ml）。相比之下，CRP 和白细胞在 3 组患者中没有显著差异。所有血管内病因患者均可检测到 BDL，水平一般比其他感染类型高 10-30 倍。死亡患者的 BDL 中位数为 85 cfu/ml，高于幸存者的 BDL 中位数 29 cfu/ml，但无统计学意义。
在金黄色葡萄球菌菌血症中，与血管外起源相比，血管内感染患者的病原体特异性 BDL 明显更高。由于 PCR 测定 BDL 可以很容易地应用于常规诊断，它可以通过快速识别需要更高剂量抗生素和其他措施来改善预后的患者亚组，从而改善 SAB 的诊断。
