Objective In childhood, the cause of neutropenia is a challenging diagnosis with a spectrum of underlying etiologies. This study was performed to investigate the clinical picture and the outcomes associated with the new onset neutropenia in previously healthy children, and to determine the risk of serious bacterial infection (SBI) in those patients.

Methods Patients presenting between January 2018 and September 2018 with an absolute neutrophil count (ANC) <1,500/μL were retrospectively evaluated. Patients with known underlying chronic disease or immunosuppressive conditions were excluded. Neutropenia was categorized into three groups: mild, 1,000–1,500/μL; moderate, 500 to <1,000/μL; and severe <500/μL.

Results A total of 423 patients were investigated. There were 156 (36.9%), 193 (45.6%), and 74 (17.5%) patients in the mild, moderate, and severe groups, respectively. Bacteremia was detected in one (0.02%) patient and SBI in 21 (4.9%) patients. No significant correlation was found between the incidence of SBI and bacterial infection rate among different age groups (p > 0.05). The incidence of SBI varied significantly according to the severity of the neutropenia (p = 0.012) and as the neutropenia became more severe, the incidence of SBI increased (p = 0.015).

Conclusion The clinical outcome of neutropenia in previously healthy and immunocompetent children is generally good with a relatively low incidence of SBI. We suggest that aggressive therapy and frequent follow-up should be reserved for previously healthy neutropenic children with SBI.

目的 在儿童时期，嗜中性白血球减少症的病因具有多种潜在病因，是一项具有挑战性的诊断。进行这项研究的目的是调查先前健康儿童的临床表现以及与新发中性粒细胞减少相关的结局，并确定这些患者发生严重细菌感染（SBI）的风险。

方法 回顾性分析2018年1月至2018年9月期间中性粒细胞绝对计数（ANC）<1,500 /μL的患者。排除患有已知潜在的慢性疾病或免疫抑制状况的患者。嗜中性白血球减少症分为三类：轻度，1,000–1,500 /μL；轻度；中度，500至<1,000 /μL; 和严重<500 /μL。

结果 共调查423例患者。轻度，中度和重度组分别有156（36.9％），193（45.6％）和74（17.5％）患者。1名患者（0.02％）检测到细菌血症，21名患者（4.9％）检测到SBI。在不同年龄组之间，SBI的发生率与细菌感染率之间没有显着相关性（p  > 0.05）。SBI的发生率根据中性粒细胞减少症的严重程度而有显着变化（p  = 0.012），并且随着中性粒细胞减少症的严重程度增加，SBI的发生率也会增加（p  = 0.015）。

结论 先前健康且具有免疫能力的儿童中性粒细胞减少症的临床结局通常良好，而SBI的发生率相对较低。我们建议，对于先前健康的中性粒细胞减少性SBI儿童，应保留积极的治疗和频繁的随访。