新生兒腸病毒感染之臨床表現及病毒特徵研究

Abstract

概論 腸病毒為一群病毒的總稱。腸病毒感染可在新生兒引起一些較嚴重的臨床表現並且造成死亡。新生兒嚴重腸病毒感染的危險因子包括早產、合併多器官的感染、出生一週內發病等。但為何有些腸病毒只造成非特異性發燒的輕微症狀，有些病毒株卻引起嚴重感染併發症，原因目前並不清楚。本研究的目的為探討腸病毒複製能力在輕、重症病人是否有差異，並以伊科病毒11型為代表作相關研究。除此之外，也同時探討不同嚴重度的病人的臨床表現。 研究方法 此回溯性研究於馬偕醫院及台大兒童醫院進行，期間為2008年1月至2018年12月，收集出生一個月內合併檢體培養出腸病毒或PCR診斷的新生兒。病人分成二組：一組為發燒無特別症狀；腦膜炎、腦炎、心肌炎及壞死性肝炎的病人分在嚴重腸病毒感染組別。我們實驗使用從輕症及重症病人分離出的伊科病毒11型病毒株在橫紋肌瘤細胞株培養放大病毒量，之後做病毒斑點試驗測定病毒量。將病毒株分別培養於37℃及39℃以觀察生長曲線並用qRT-PCR定量。 研究結果 在研究期間共113位病人符合條件，表現發燒且無其他症狀的病人有61位（54.0%），另一嚴重腸病毒感染的組別：42位(37.2%)表現無菌性腦膜炎或腦膜腦炎；10位為壞死性肝炎及心肌炎合併腦麻炎。共有2位病人死亡。比較二組病人之臨床表現及實驗室數據發現，嚴重腸病毒組的入院時及住院期間最高白血球數比輕微發燒組多，具統計學上的意義(p=0.0039 及0.0004)。嚴重組的病人較多於出生14天內發病(p=0.022)。嚴重組及輕微組共4株病毒在感染後24及36小時，37℃測出來的病毒量均比39℃多且細胞病變作用 (Cytopathic effect)在37℃會較早出現。分別比較嚴重組及輕微組病毒株在37℃及39℃的病毒量並無明顯差異。 結論 腸病毒感染併發重症的病人發病時間相對輕微發燒的病人早。與過去台灣的研究相比，致死病例在此次研究期間較少。在39℃時伊科病毒11型的病毒複製能力會被抑制。其他影響新生兒腸病毒感染的危險因子需要後續更多的研究

Introduction Nonpolio enteroviruses (EV) cause serious diseases and associated with high mortality rate in neonates. Several factors for severe EV infection were reported. Whether some enterovirus strains caused fatal disease and some only caused nonspecific febrile illness is not clear. In this study, we used echovirus 11 as a representative and aimed to investigate replication capacity of echovirus 11 strains isolated from patients with severe complication and with nonspecific febrile. In addition, clinical and laboratory data of patients with all types enterovial infection were analyzed to figure out differences between severe and mild neonatal EV infections. Methods This retrospective study was conducted in Mackay Memorial and Children Hospital and National Taiwan University Children Hospital. Patients aged ≤ 30 days with culture or PCR proved EV infections were collected from January 2008 to December 2018. Demographic and laboratory date of patients was recorded and analyzed. We obtained echovirus 11 strains isolated from patients with severe complication and from nonspecific febrile. Viral strains were cultured in Rhabdomyosarcoma (RD) cell for propagation and measured titer by plaque assays. Then, growth curves of echovirus 11 strains were performed at 37℃ and 39.5℃ and harvest for quantified by real-time quantitative PCR (qRT-PCR). Two-sample t-test and Chi-square test was performed for statistics. A p < 0.05 was considered statistically significant. Results We collected 113 patients and 61 (54.0%) patients was in nonspecific febrile illness group. Forty-two (37.2%) had aseptic meningitis and 10 patients had myocarditis or hepatic necrosis with coagulopathy including in severe group. There were two fatal cases. WBC counts at admission and maximum WBC counts during hospitalization both higher in severe group (p=0.0039 and 0.0004, respectively). The disease onset of patients in severe group was younger than in severe group (p=0.022). The viral load of 4 echovirus 11 strains cultured at 39.5℃ was lower than that at 37℃ harvested at 24 hours and 36 hours post infection. Comparing severe and mild stains cultured at 39.5℃ and 37℃, respectively, viral load were not significant different at measured time points. Conclusion The onset of disease is younger in patients with severe complication than in that with nonspecific febrile illness. The fatal cases decreased comparing to previous study in Taiwan. The replication capacity of echovirus 11 strains was inhibited at 39℃. Determinants of EV virulent in neonates require further research.