Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan.
BMC Infect Dis. 2021 Nov 26;21(1):1192. doi: 10.1186/s12879-021-06880-4.
Bacteremia due to the Streptococcus bovis/Streptococcus equinus complex (SBSEC) is associated with specific diseases, such as colorectal cancer and infective endocarditis. This study aimed to evaluate the clinical characteristics of SBSEC bacteremia and the accuracy of identification of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and phenotypic identification systems for SBSEC isolates.
We analyzed patients with SBSEC bacteremia retrospectively between 2012 and 2019 at three hospitals in Japan. We re-identified each SBSEC isolate using sequencing superoxide dismutase (sodA) analysis, MALDI-TOF MS using the MALDI Biotyper, and phenotypic identification using the VITEK2.
During the study period, 39 patients with SBSEC bacteremia were identified. S. gallolyticus subsp. pasteurianus (SGSP, n = 29), S. gallolyticus subsp. gallolyticus (SGSG, n = 5), S. lutetiensis (SL, n = 4), and S. infantarius subsp. infantarius (n = 1) were identified using sodA sequencing analysis. Primary bacteremia (36%) was the most common cause of bacteremia, followed by infective endocarditis (26%) and biliary tract infections (23%). Colorectal cancer was associated significantly with SGSG bacteremia, while the sources of bacteremia were similar in each SBSEC subspecies. The MALDI Biotyper was significantly more accurate in identifying the SBSEC isolates at the subspecies level compared to the VITEK2 (92% vs. 67%, P = 0.010). In contrast, there were no significant differences in the rates of correct identification of the SBSEC isolates at the species level between the MALDI Biotyper and the VITEK2 (100% vs. 87%, P = 0.055).
Bacteremia with SGSG was associated with colorectal cancer, and the sources of bacteremia were similar in each SBSEC subspecies. The MALDI-TOF MS was significantly more accurate in identifying SBSEC isolates at the subspecies level than the phenotypic identification systems. The accurate identification of SBSEC isolates using the MALDI-TOF MS and phenotypic identification systems was sufficient at the species level, but it was insufficient at the subspecies level. Therefore, it may be reasonable for clinicians to perform echocardiographies and colonoscopies in all patients with SBSEC bacteremia.
牛链球菌/马肠链球菌复合群（SBSEC）引起的菌血症与结直肠癌和感染性心内膜炎等特定疾病有关。本研究旨在评估 SBSEC 菌血症的临床特征，以及基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）和表型鉴定系统对 SBSEC 分离株鉴定的准确性。
我们回顾性分析了 2012 年至 2019 年期间在日本三家医院发生的 39 例 SBSEC 菌血症患者。我们使用测序超氧化物歧化酶（sodA）分析、MALDI Biotyper 进行 MALDI-TOF MS 以及 VITEK2 进行表型鉴定，重新鉴定了每一株 SBSEC 分离株。
在研究期间，共鉴定出 39 例 SBSEC 菌血症患者。采用 sodA 测序分析，鉴定出牛链球菌亚种 pasteurianus（SGSP，n=29）、牛链球菌亚种 gallolyticus（SGSG，n=5）、中间链球菌（SL，n=4）和婴儿链球菌亚种婴儿型（n=1）。原发性菌血症（36%）是最常见的菌血症病因，其次是感染性心内膜炎（26%）和胆道感染（23%）。结直肠癌与 SGSG 菌血症显著相关，而每种 SBSEC 亚种的菌血症来源相似。与 VITEK2 相比，MALDI Biotyper 对 SBSEC 分离株亚种水平的鉴定明显更准确（92%比 67%，P=0.010）。相比之下，MALDI Biotyper 和 VITEK2 对 SBSEC 分离株种水平的正确鉴定率无显著差异（100%比 87%，P=0.055）。
SGSG 引起的菌血症与结直肠癌有关，每种 SBSEC 亚种的菌血症来源相似。MALDI-TOF MS 对 SBSEC 分离株亚种水平的鉴定明显优于表型鉴定系统。MALDI-TOF MS 和表型鉴定系统对 SBSEC 分离株的准确鉴定在种水平上是足够的，但在亚种水平上是不够的。因此，对于所有 SBSEC 菌血症患者，临床医生可能需要进行超声心动图和结肠镜检查。
