Pneumococcal colonization among tracheostomy tube dependent children

Streptococcus pneumoniae colonization is a precursor to pneumococcal disease. Although children with a tracheostomy have an increased risk of pneumococcal pneumonia, the pneumococci colonizing their lower airways remain largely uncharacterized. We sought to compare lower respiratory tract isolates colonizing tracheostomy patients and a convenience sample of isolates from individuals intubated for acute conditions. We collected pneumococcal isolates from the lower respiratory tract of 27 patients with a tracheostomy and 42 patients intubated for acute conditions. We compared the penicillin susceptibility, rates of co-colonization, genetic background, and serotype of isolates colonizing these patient populations. Isolates from both groups showed high genetic diversity. Forty multi-locus sequence types and 20 serotypes were identified. There was no significant difference in serotype distribution, co-colonization rates, vaccine coverage, or non-susceptibility to penicillin among pneumococcal isolates from the two groups. Colonization of the lower airways with non-vaccine serotypes 15B/C, 23B and 35B was noted for the first time in patients with tracheostomies and supports recently observed increases in nasopharyngeal colonization and disease due to these serotypes.

肺炎链球菌（Streptococcus pneumoniae）定植是肺炎球菌疾病的前驱事件。尽管接受气管造口术的儿童罹患肺炎球菌肺炎的风险显著升高，但定植于其下呼吸道的肺炎链球菌仍未得到充分表征。本研究旨在对比定植于气管造口术患者的下呼吸道分离株，与因急性疾病接受插管的个体的便利样本分离株。我们从27名气管造口术患者及42名因急性疾病接受插管的患者的下呼吸道中采集了肺炎链球菌分离株，并比较了这两类患者群体定植分离株的青霉素敏感性、共同定植率、遗传背景与血清型。两类群体的分离株均呈现出较高的遗传多样性，共鉴定出40个多位点序列型（multi-locus sequence types）与20种血清型。两组肺炎链球菌分离株在血清型分布、共同定植率、疫苗覆盖范围以及青霉素非敏感性方面均无显著差异。本研究首次在气管造口术患者中发现非疫苗血清型15B/C、23B及35B定植于下呼吸道，该发现佐证了近期观察到的由这些血清型引发的鼻咽定植与疾病发生率上升的现象。