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Objective:To establish a classification model for rapid identification of hypervirulent subtype ST17 clones of Group B Streptococcus (GBS) using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS).Methods:In a retrospective study, 235 strains of GBS strains were selected from multiple centers in China during 2015-2018. For model generation,45 strains of ST17 and 50 strains of non-ST17 (20 ST19, 15 ST12 and 15 ST10 strains) were enrolled as the modeling group. The remaining 90 main ST strains (40 ST17, 16 ST10, 17 ST12 and 17 ST19) were served as validation group. 50 GBS strains classified as other minor ST subtypes were regarded as taxonomic groups. MS spectra were collected by Bruker mass spectrometry, and then loaded for model generation and verification, and screening of differential peptide peaks by genetic algorithm (GA) and model verification on ClinProTools 3.0 software.Results:The recognition rate for ST17-GA model were 99.4% with cross validation value of 96.9%. Among the ten differential peptide peaks for the classification model, the weights of both two main peptide peaks m/z 2 956 and m/z 5 912 were greater than 1, while the weights of the all other eight peptide peaks were less than 0.5. Model validation showed only one of the ST17 was misjudged as non-ST17 strain, resulting in diagnostic accuracy of 98.9%, sensitivity of 97.5% and specificity of 100%, positive predictive value of 100% and negative predictive value of 98.0%, respectively. For other sporadic STs, 42.0% (21/50) of them were misdiagnosed as ST17 subtype.Conclusion:A MALDI-TOF MS classification model for hypervirulent subtype of ST17 GBS strains has been successfully established with good diagnostic efficacy.
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Objective To explore the sample type and drug resistance characteristics of Streptococcus pneu-monia(Spn)isolated from pediatric patients in Guangzhou district,and their age distribution to offer instruc-tions for prevention and clinical treatment.Methods Spn isolates were cultured and identified according to the national standard procedure for clinical laboratory operation,followed by analysis of sample type and age dis-tribution of pediatric patients with positive isolates of Spn in Guangzhou Women and Children′s Medical Cen-ter from 2013 Jan 1st to 2015 Dec 31st,drug resistance status was determined by MIC test.Results Totally, 1 243 strains of Spn were isolated,which were mainly from pediatric patients under 1 year old(42.80%).Spn isolates were mainly isolated from respiratory tract(72.81%),ear secretions(15.37%),blood(5.63%),cere-brospinal fluid(3.06%)and hydrothorax(2.01%).For all Spn isolates,the resistance rate to erythromycin, tetracycline and sulfamethoxazole was especially high as 94.93%,85.76%,73.53% respectively,with relative high resistance to penicillin G(24.70%),amoxicillin(39.59%),ceftriaxone(24.05%),meropenem(22.85%) and cefotaxime(19.89%),low resistance to quinolone antibiotics(<10.00%),and no resistance to vancomycin and linezolid.Conclusion The major age group of children with Spn infection is infants under one year old in Guangzhou,clinicians should be serious about the high resistant rate of Spn to erythromycin,tetracycline and sulfamethoxazole,the significantly increased resistant rate to penicillin,amoxicillin and ceftriaxone.Clinicians should choose antibiotics rationally according to the characteristics of drug sensitivity for better treatment.
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Objective To explore the infection rate of hepadnaviruses and non-hepatotropic virus in infants with biliary atresia(BA)and their relationship between the onset and development of BA.Methods The data and pathogen test records from 184 BA infants who were hospitalized at Guangzhou Women and Children's Medical Center from January 1,2010 to December 31,2014 were reviewed,and the infection rates caused by 3 hepadnaviruses including hepatitis A virus(HAV),hepatitis B virus(HBV),hepatitis E virus(HEV)as well as 5 non-hepatotropic viruses including cytomegalovirus(CMV),Epstein-Barr virus(EBV),herpes simplex virus(HSV),enterovirus(EV),Coxsackie-virus were analyzed.The outpatients or inpatients without BA and immunodeficiency were selected as controls.Results In BA patients,the infection rates of CMV were highest(40.21％,39/97 cases)caused by 3 hepadnaviruses(HAV,HBV,HEV)and 5 non-hepatotropic viruses(CMV,EBV,HSV,EV,Cox),while the infection rates of HAV,HEV,HBV,EBV,HSV,EV or Coxsackievirus were all low,and mixed virus infection was found in 9 patients.The positive rate of CMV IgM in BA group[34.94％(29/83 cases)] was significantly higher than that in the control group[15.69％(8/51 cases)],and the difference was statistically significant(x2=5.86,P0.05).No statistical difference in age was found in BA patients on detection between the positive and the negative group,and the consistency of CMV DNA and CMV IgM was not ideal(Kappa value<0.4).Conclusions Infection of CMV is quite common in BA patients,BA infants under 60 days old show higher detection rate of CMV DNA than the older ones,but there is no difference in detection rate of CMV IgM among different ages,CMV is not supported as a secondary infection and may play a role in the occurrence and development of BA.
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Objective To explore the main pathogenic bacteria and antibiotic resistance patterns in children with bacterial diar‐rhea from Guangzhou region .Methods Regular bacterial culture of stool samples from children with suspicious bacterial diarrhea was performed to isolate the pathogen during 2011 to 2012 ,followed by the analysis of its composition and serum type ,ward distri‐bution characteristics and drug resistance to 12 antimicrobacterial drugs .Results 416 strains of pathogenic bacteria were isolated from diarrhea children during 2011-2012 ,in which salmonella ,enteropathogenic E .coli ,Campylobacter jejuni and Candida albicans isolates accounted for 53 .61% ,37 .98% ,5 .29% and 1 .68% respectively .Drug resistance rate of the main strains to 12 antimicrobi‐al agents was 85 .25% to ampicillin ,54 .28% to compound sulfamethoxazole ,44 .70% to cefotaxime ,42 .53% to ceftriaxone , 40 .66% to chloramphenicol ,23 .55% to ceftazidime ,23 .36% to aztreonam ,14 .88% to ciprofloxacin ,8 .07% to cefepime ,7 .99% to cefperazone/sulbactam ,7 .42% to piperacillin/tazobactam respectively ,and no resistance to imipenem was detected .Conclusion The pathogenic bacteria causing diarrhea mainly includes salmonella ,pathogenic e .coli ,campylobacter jejuni in children from guang‐zhou region ,the top five sensitive antimicrobial reagents for the main strains includes imipenem ,piperacillin/tazobactam ,cefpera‐zone/sulbactam ,cefepime and ciprofloxacin .
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Objective:To explore the effect of heterogeneous nuclear ribonucleoprotein K(hnRNP K)short hairpin RNA(shRNA)on K562 cells. Methods:hnRNP K shRNA retrovirus was packaged with pSUPER retro hnRNP K shRNA after its identification by enzyme digestion and sequencing analysis,then FCM,Wright staining,MTT assay,RT-PCR were used to analyze its effects on cell cycle and apoptosis,proliferation,hnRNP K and eukaryotic translation initiation factor-4E(eIF4E) mRNA of K562 cells respectively. Results:The sequence of the inserted fragment in pSUPER retro hnRNP K shRNA was correct. Compared with the control K562 cells,hnRNP K shRNA treated group showed significantly more cells at G2/M phase(P