Molecular Typing And Antibiotic Resistance Of Streptococcus Pneumoniae Isolated From Children

Objective: According to the 416 strains of Streptococcus pneumoniae(Spn)collected by the Hebei Provincial Center for Disease Control and Prevention,the epidemiological characteristics and clinical characteristics of Spn were analyzed.The serotypes were performed using PCR and the coverage of vaccine were statistics by SPSS19.0.Multilocus sequence typing(MLST)was performed to determine the STs of the invasive Spn,and antibiotic resistance was analysed using the microdilution broth method.In addition,we evaluated the connection of the serotypes and STs with the resistance.This study investigate the molecular characterization and the distribution of serotypes and the STs for the vaccine strategy in Hebei.In addition,The antibiotic resistance results provide a reference for clinicians to choose antibiotics.Methods: From January 2014 to December 2016,the Hebei Provincial Center for Disease Control and Prevention collected 416 strains of Streptococcus pneumoniae from children's hospital of Hebei Province,which were non-repetitive.We analyzed the epidemiological characteristics of their clinical characteristics.The Streptococcus pneumoniae were indentified by Optochin sensitivity test and bile dissolution test.Using Multi-polymerase chain reaction(mPCR)to determine the species and serotypes typing of all strains.Seven housekeeping genes were sequenced to identify the sequence types(STs).BioNumerics software was applied to statistic the data.Antibiotic resistance was analysed using the microdilution.Results:1.clinical characteristics: 416 non-repetitive strains were isolated from children under 14 years old and 370(88.94%)strains were isolated from children under 2 years old.88 cases were diagnosed as invasive pneumococcal disease(IPD),328 cases were diagnosed as non-invasive pneumococcal disease(NIPD).The sample of IPD were collected from blood specimens(41 strains,46.59%)and cerebral spinal fluid(CSF)(18 strains,20.45%).The sample of NIPD were sputum(307 strains,93.6%).170 strains(40.87%)of Spn were isolated from spring and 139 strains(24.28%)from winter.Among 416 Spn isolates,271 were male and 145 were female.The ratio of male to female was 1.87:1.2.Biochemical results: 416 non-repetitive strains were identified as Spn by Optochin susceptibility test and bile dissolution test.The specific bands of cpsA gene were identified by mPCR,which further indicated that 416 strains were all Spn.3.Identification of serotype of Spn strain and coverage of vaccine: Among 416 Spn strains,383(92.07%)were successfully serotyped and 23 serotypes were detected.The prevalent serotypes were 19 F,6A/6B,19 A,6C/6D,14 and 23 F.The coverage rates of PCV7,PCV10 and PCV13 were 43.27%,46.15% and 86.06% respectively.The coverage rates of the three vaccines were significantly different in IPD,NIPD and IPD+NIPD groups(P<0.001).The coverage rates of PCV13 vaccines were higher than those of PCV7 and PCV10.4.Relationship between STs and serotypes: 87 of 88 invasive Spn strains were successfully typed.38 ST types were detected,of which 7 belonged to new ST type.The predominant STs was ST-271,ST-320,ST-2248,ST-876 and ST-2296,and grouping 47 Spn strains into 6 clonal complex(CC),mainly CC271,CC876.The predominant serotype of ST-271 was 19 F,and the predominant serotype of ST-320 was 19 A.5.Antibiotic resistance: 85 invasive Spn strains were completely sensitive to linezolid and levofloxacin.98.82% of the strains were sensitive to vancomycin,but most of them showed high resistance to erythromycin(98.82%),clindamycin(97.65%),penicillin meningitis(76.27%)and Sulfamethoxazole-Trimethoprime(64.71%).85.88% of the strains showed multi-drug resistance,the predominant multi-drug resistance model was penicillin / Sulfamethoxazole-Trimethoprime/ erythromycin / clindamycin.There were significant differences in the resistance among different serotypes to penicillin,meropenem,compound trimethoprim,cefotaxime and ceftriaxone(P<0.001),indicating that the resistance of different serotypes was different.Conclusions:1.The prevalent serotypes of Spn in this study were 19 F,6A/6B,19 A,6C/6D,14 and 23 F.The coverage rate of PCV13 vaccine reached 86.06%,which means PCV13 had a good coverage effect,suggesting that the introduction of PCV13 vaccine in children in Hebei Province is of great significance for the prevention and control of PDs.2.ST-271(19F)and ST-320(19A)were the predominant STs of IPD,which belonged to CC271.No new serotypes and clones were found.3.The antibiotic resistance of invasive Spn strains in this study is serious.The resistance rates of erythromycin and clindamycin were over 97%,but all of them were sensitive to linezolid,levofloxacin and vancomycin.85.88% of invasive Spn strains showed multi-drug resistance,and the difference of antibiotic resistance rate between different serotypes was significant.