| Objective: To investigate the epidemiological characteristics and clinical characteristics of the 111 strains of Streptococcus pneumoniae(Spn)collected from children.The serotypes were performed using PCR and the coverage of vaccine serotypes was statisticed by SPSS19.0.Antibiotic resistance was analyzed with the microdilution broth method.This study investigate the connection among the distribution of serotypes,coverage of vaccine and Antibiotic resistance.The distribution of serotypes could provide data support for the development and selection of related vaccines.In addition,the antibiotic resistance results provide clinicians a reference for choosing antibiotics.Methods: One hundred and eleven strains of Streptococcus pneumoniae were collected from Children's Hospital of Hebei Province from January 2017 to December 2018.We analyzed the clinical characteristics and epidemiological characteristics of the cases.Using Optochin sensitivity test and bile dissolution test to indentify Streptococcus pneumoniae.Multi-polymerase chain reaction(m PCR)was used to determine the serotypes of all strains.The virulence and drug resistance genes were detected by regular PCR.Antibiotic resistance was analyzed using the microdilution.Results:1.Clinical characteristics: One hundred and eleven strains were isolated from children up to 12 years old and 95(85.59%)strains were isolated from children under 5 years old.73 strains were isolated from cases which diagnosed as invasive pneumococcal disease(IPD),38 strains were isolated from cases which diagnosed as non-invasive pneumococcal disease(NIPD).The sample of IPD were mainly collected from blood specimens(53 strains,72.60%)and cerebral spinal fluid(CSF)(16 strains,21.92%).The sample of NIPD were were mainly collected from facial secretions(20 strains,52.63%)and pus(16 strains,42.11%).Among 111 Spn isolates,61 were collected from male and 145 were collected from female.The ratio of male to female was 1.22:1.2.Biochemical results: One hundred and eleven isolates were identified as Spn through Optochin susceptibility test and bile dissolution test.The specific bands of cps A gene were identified by m PCR,which further indicated that 111 isolates were all Spn.3.Identification of serotype of Spn strain and coverage of vaccine: 107(96.40%)of 111 Spn strains were serotyped successfully and 23 serotypes were detected.The prevalent serotypes were 19 F,19A,14,6 and 23 F.The coverage rates of PCV7,PCV10 and PCV13 were 60.36%,67.57% and 87.39% respectively.The coverage rates of the three vaccines were significantly different among PDs,IPD and NIPD groups(P<0.05).The coverage rates of PCV13 vaccines were higher than those of PCV7.For children over 2 years old,the coverage rates of PCV13 vaccine and PPSV23 vaccine was higher than that of PCV7 vaccine.There was no significant difference in coverage rates between PCV13 and PPSV23.4.Carrying rate of virulence genes and drug resistance genes: The carrying rate of virulence genes lyt A,lyt B and nan A was 100%,followed by pav,iga,ply and hys A,with the carrying rates of 97.30%,95.50%,98.20% and 92.79%,respectively.The carrying rate of rrg A was 38.74%.Among erythromycin related drug resistance genes,the carrying rate of erm(B)gene and mef(A/E)gene were 96.40% and 32.43%,respectively;The rate of tet(m)and gyr A were 95.50% and 97.30%,respectively.5.Antibiotic resistance: One hundred and ten Spn strains were detected successfully by antibiotic resistance test.One hundred and ten Spn strains were completely sensitive to vancomycin and levofloxacin.Most of the strains were sensitive to rifampicin(99.09%)and chloramghenicol(90.91%),but most of them showed high resistance to penicillin meningitis(81.25%),erythromycin(100%),clindamycin(96.36%),doxycycline(80.91%)and ulfamethoxazole-trimethoprime(58.18%).89.09% of the strains showed multi-drug resistance,the predominant multi-drug resistance model was erythromycin/clindamycin/ doxycycline/ sulfamethoxazole-trimethoprime.There were significant differences in antibiotic resistance among different serotypes to penicillin,doxycycline,sulfamethoxazole-trimethoprime and chloramghenicol(P<0.05),indicating that the resistance of different serotypes were different.Conclusions:1.In this study,among the streptococcus pneumoniae cases of children,IPD cases were the majority in terms of classification,and children under 5 years old were the majority in terms of age.2.The prevalent serotypes of Spn isolates from 2017 to 2018 in this study were 19 F,19A,14,6,and 23 F.The coverage rate of PCV13 vaccine reached to 86.06%,higher than that of other vaccines.The introduction of pcv13 vaccine in the population of this study is of great significance for the prevention and control of Streptococcus pneumoniae disease.Except for PCV13,PPSV23 vaccine can also be used for children over 2 years old in the region when economic conditions are considered.3.The carriage rate of rrg A gene in serotypes 19 A and 19 F was higher than other serotypes.Gene rrg A may be related to the high morbidity and pathogenicity of serotypes 19 A and 19 F.The resistance mechanisms of erythromycin and tetracycline in this area were mainly mediated by erm(B)and tet(M),respectively.4.The antibiotic resistance of Spn isolates from 2017 to 2018 in this study was serious.The resistance of erythromycin and clindamycin was serious,but most of them were sensitive to vancomycin,levofloxacin and rifampicin.In this study,most of Spn strains showed multi-drug resistance,and the difference of antibiotic resistance rate among different serotypes was significant. |
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