Ajdler-Schaeffler Evelyne, Scherrer Alexandra U, Keller Peter M, Anagnostopoulos Alexia, Hofmann Michael, Rancic Zoran, Zinkernagel Annelies S, Bloemberg Guido V, Hasse Barbara K
Division of Infectious Diseases and Hospital Epidemiology, University Hospital and University of Zurich, Zurich, Switzerland.
Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
Front Med (Lausanne). 2018 Jun 4;5:169. doi: 10.3389/fmed.2018.00169. eCollection 2018.
Vascular graft infections (VGI) are difficult to diagnose and treat, and despite redo surgery combined with antimicrobial treatment, outcomes are often poor. VGI diagnosis is based on a combination of clinical, radiological, laboratory and microbiological criteria. However, as many of the VGI patients are already under antimicrobial treatment at the time of redo surgery, microbiological identification is often difficult and bacterial cultures often remain negative rendering targeted treatment impossible. We aimed to assess the benefit of 16S rRNA gene polymerase chain reaction (broad-range PCR) for better microbiological identification in patients with VGI. We prospectively analyzed the clinical, microbiological, and treatment data of patients enrolled in the observational Vascular Graft Cohort Study (VASGRA), University Hospital Zurich, Switzerland. The routine diagnostic work-up involved microbiological cultures of minced tissue samples, and the use of molecular techniques in parallel. Patient-related and microbiological data were assessed in descriptive analyses, and we calculated sensitivity, specificity, negative and positive predictive value for broad-range 16S rRNA gene PCR versus culture (considered as gold standard). We investigated 60 patients (median age 66 years (Interquartile range [IQR] 59-75)) with confirmed VGI between May 2013 and July 2017. The prevalence of antimicrobial pretreatment at the time of sampling was high [91%; median days of antibiotics 7 days (IQR 1-18)]. We investigated 226 microbiological specimens. Thereof, 176 (78%) were culture-negative and 50 (22%) were culture-positive. There was a concordance of 70% (158/226) between conventional culture and broad-range PCR (sensitivity 58% (95% CI 43-72); specificity 74% (67-80%)). Among the group of 176 culture-negative specimens, 46 specimens were broad-range PCR-positive resulting in identification of overall 69 species. Among the culture and/or broad-range PCR-positive specimens ( = 96), 74 (77%) were monomicrobial and 22 (23%) polymicrobial, whereas the rate of polymicrobial samples was higher in broad-range PCR-positive specimens (93%). Combined cultures and broad-range 16S rRNA gene PCR from periprosthetic tissue and/or explanted vascular grafts increased the diagnostic accuracy in VGI, particularly in patients already under antimicrobial treatment at the time of redo surgery. Ideally, antimicrobial treatment should be withheld until surgical sampling in order to optimize microbiological diagnostics.Clinical trials.gov identifier: NCT01821664.
血管移植物感染（VGI）难以诊断和治疗，尽管进行了再次手术并联合抗菌治疗，但结果往往不佳。VGI的诊断基于临床、放射学、实验室和微生物学标准的综合判断。然而，由于许多VGI患者在再次手术时已经接受抗菌治疗，微生物鉴定往往很困难，细菌培养常常呈阴性，导致无法进行针对性治疗。我们旨在评估16S rRNA基因聚合酶链反应（广谱PCR）在VGI患者中进行更好的微生物鉴定的益处。我们前瞻性地分析了瑞士苏黎世大学医院观察性血管移植物队列研究（VASGRA）中患者的临床、微生物学和治疗数据。常规诊断检查包括切碎组织样本的微生物培养，并同时使用分子技术。在描述性分析中评估了患者相关和微生物学数据，我们计算了广谱16S rRNA基因PCR相对于培养（视为金标准）的敏感性、特异性、阴性和阳性预测值。我们调查了2013年5月至2017年7月期间确诊为VGI的60例患者（中位年龄66岁（四分位间距[IQR]59 - 75））。采样时抗菌药物预处理的患病率很高[91%；抗生素中位使用天数7天（IQR 1 - 18）]。我们调查了226份微生物标本。其中，176份（78%）培养阴性，50份（22%）培养阳性。传统培养与广谱PCR之间的一致性为70%（158/226）（敏感性58%（95%CI 43 - 72）；特异性74%（67 - 80%））。在176份培养阴性的标本中，46份标本广谱PCR呈阳性，共鉴定出69种菌种。在培养和/或广谱PCR阳性的标本（=96）中，74份（77%）为单微生物感染，22份（23%）为多微生物感染，而广谱PCR阳性标本中多微生物样本的比例更高（93%）。来自假体周围组织和/或取出的血管移植物的联合培养和广谱16S rRNA基因PCR提高了VGI的诊断准确性，特别是对于在再次手术时已经接受抗菌治疗的患者。理想情况下，应在手术采样前停用抗菌治疗，以优化微生物诊断。临床试验注册号：NCT01821664。
