Abstract: 　Objective　To understand the distribution of bacterial etiology and drug resistance in children with severe pneumonia. Methods　The hospitalized children who were diagnosed with severe pneumonia in our hospital from January 2016 to September 2017 and completed the bacterial pathogen examination of nasopharyngeal aspirate (NPA) and bronchoalveolar lavage fluid (BALF) were enrolled, and clinical data, NPA, BALF bacterial pathogen detection and bacterial drug susceptibility results were retrospectively analyzed. Results　A total of 316 children with severe pneumonia were enrolled, including 169 infants (53.5%), 204 babies (64.6%) who had a combination of underlying disease and 304 babies (96.2%) who had complications. The first bacteria detected from NPA and BALF were Streptococcus pneumoniae. The resistance rate of Streptococcus pneumoniae to erythromycin was over 98%, and the resistance rate to tetracycline, compound sulfamethoxazole and clindamycin was over 70%. The resistance rate of meropenem is as high as 55%, the resistance rate to penicillin is less than 20%, the resistance rate to amoxicillin and cefotaxime is less than 30%, and in contrast, it is sensitive to vancomycin, rifampicin and linezolid. The second bacteria detected by NPA and BALF is Haemophilus influenzae, and its resistance rate to ampicillin is over 85%. It is resistant to compound sulfamethoxazole, cefaclor, cefuroxime and amoxicillin clavulanate potassium. The drug resistant rate is more than 55%, but the sensitivity rate to cefotaxime is as high as 80%. The resistance rate of Klebsiella pneumoniae to ampicillin was 100%, the resistance rate to cefotaxime and ceftriaxone was over 55%, but the sensitivity to carbapenem antibiotics (meropenem, imipenem) is up to 80%. ESBLs-producing Klebsiella pneumoniae in BALF and NPA was 13 and 6 strains, respectively. The detection rate of Klebsiella pneumoniae from BALF was significantly higher than that from NPA (76.5% vs 37.5%, P <0.05). Conclusions　The most common bacterial pathogen detected in children with severe pneumonia is Streptococcus pneumoniae, which still maintains high sensitivity to penicillin and amoxicillin. Broad-spectrum antibiotic treatment may lead to more frequently detected ESBLs-producing Klebsiella pneumoniae. Appropriate antibiotic use has important role in preventing the emergence of resistant strains.

Key words: severe pneumonia;　bacterial cultivation;　resistance;　child