Microbiological and clinical characteristics of Elective ND and PICU ND patients.

(No patients had tracheostomies in place)Microbiological and clinical characteristics of Elective ND and PICU ND patients.（无患者留置气管切开套管）择期ND患者与儿科重症监护室（Pediatric Intensive Care Unit，PICU）ND患者的微生物学与临床特征。