Analysis of identification and antibiotic susceptibility of isolates identified as Streptococcus pneumoniae by routine methods with negative quellung reaction results
10.3760/cma.j.cn101070-20190827-00807
- VernacularTitle:荚膜肿胀试验阴性肺炎链球菌的菌种鉴定及其抗生素敏感性分析
- Author:
Ju JIA
1
;
Fang DONG
;
Lin YUAN
;
Wei GAO
;
Dandan LIU
;
Wei SHI
;
Kaihu YAO
Author Information
1. 国家儿童医学中心，首都医科大学附属北京儿童医院，北京市儿科研究所，教育部儿科重大疾病研究重点实验室，北京 100045
- From:
Chinese Journal of Applied Clinical Pediatrics
2020;35(8):595-599
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To determine whether these Streptococcus pneumoniae isolates identified by routine cli-nical methods that cannot be serotyped by the quellung reaction contain other species of viridans group streptococci and to determine the antibiotic susceptibility to provide reference for clinical medicine. Methods:A total of 105 isolates identified as Streptococcus pneumoniae by routine methods with negative quellung reaction results were enrolled in this study.Multilocus sequence analysis (MLSA) and matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF-MS) were used to identify species of these isolates.Broth microdilution method was used to detect susceptibilities of 14 antibiotics. Results:Twenty-four of the 105 isolates were identified as Streptococcus pseudopneumoniae by MLSA, and the remaining 81 were Streptococcus pneumoniae.Six isolates of Streptococcus pseudopneumoniae were misidentified as Streptococcus pneumoniae, and 3 isolates as Streptococcus mitis/ oralis by MALDI-TOF-MS; and 6 isolates of Streptococcus pneumoniae were misidentified as Streptococcus pseudopneumoniae.All isolates were susceptible to Vancomycin, Levofloxacin and Moxifloxacin.The non-susceptibility rates between Streptococcus Pneumoniae and Streptococcus pseudopneumoniae against Ceftriaxone(28.4% vs.58.4%), Chloramphenicol(39.5% vs.4.2%), Erythromycin(77.8% vs.95.8%) and Azithromycin(75.3% vs.95.8%) were obviously different. Conclusions:Routine clinical methods may misidentify some Streptococcus pseudopneumoniae as Streptococcus pneumoniae, and so does the MALDI-TOF-MS.In addition, Streptococcus pneumoniae isolates with negative results of the quellung reaction showed differences in antimicrobial resistance.And misidentification may affect the evaluation of pathogenic bacteria and antibiotic resistance.
