Persister bacteria have the characteristic of phenotypic resistance to the anfimicrobial drugs.The presence of such persister bacteria is considered to be one of the major causes for lengthy therapy and treatment failure.Persister bacteria are a group of special subpopulation of bacteria,and have the characteristics different from the ordinary bacteria and resistant mutants.With the improvement of scientific research and technology in recent years,we get a better understanding of persister bacteria.This paper reviewed the research progress on the characteristics of persister bacteria,formation mechanism,the impact of the clinical treatment and drug development The paper also provided the basis for diagnosis,prevention and treatment of the persister bacteria.

Objective To investigate and compare the molecular epidemiological characteristics of Streptococcus pyogenes isolates from Shanghai adult and pediatric patients in terms of antimicrobial susceptibility ,clone type ,emm type ,biofilm formation and virulence for better infection control and treatment .Methods Thirty‐nine nonduplicate clinical isolates of S . pyogenes from adult and pediatric patients were analyzed by determining the susceptibility to antimicrobial agents by Kirby‐Bauer method;clonal typing by multilocus sequence typing ( MLST ); genotyping by emm gene sequence analysis ,which encoding M protein;genomic characteristics of different emm type strains by pulsed field gel electrophoresis (PFGE );and biofilm formation by semi‐quantitative biofilm formation test . Twenty main virulence genes of S .pyogenes ,including 12 superantigen genes and 8 other key genes were detected by PCR and gel electrophoresis . Results A total of 39 nonduplicate S .pyogenes isolates were analyzed .The most common genotype was emm 12‐ST36 (64 .1% ) and emm 1‐ST28 (17 .9% ) .Isolates from adult and pediatric patients had the same dominant genotype , emm 12‐ST36 . The isolates from children showed significantly higher resistance rate to erythromycin and clindamycin than those from adult patients (P<0 .000 1) .Particular emm type and clone type were frequently identified in the same PFGE cluster .Statistical analysis showed that biofilm formation was significantly associated with emm type 1 (P=0 .005) and erythromycin/clindamycin resistance (P=0 .000 3) .The strains from children showed higher biofilm formation than those from adult patients (P<0 .000 1) .We found that virulence genes speA ,speJ and spd3 were significantly associated with emm type 1 (P<0 .000 1 ,P=0 .005 5 ,P<0 .000 1) ,while speI and sic were significantly associated with emm type 12 (both P<0 .000 1) .We also found that the prevalence of speC ,speH ,ssa , smeZ ,and sdaD genes was significantly different between emm type 12 and emm type 1 (P= 0 .023 8 , P< 0 .000 1 , P<0.0001,P= 0.0003,and P= 0.0068,respectively).TheprevalenceofvirulencegenesspeH,smeZandsdaDwas significantly different between the emm type 12 strains from children and those from adults (all P< 0 .000 1) .Conclusions There is a strong agreement between emm type ,clone type ,virulence genes and the clusters defined by PFGE profiling of S . pyogenes .S .pyogenes isolates from adult and pediatric patients are different in terms of antibiotic resistance and biofilm formation .Certain emm type is significantly associated with antibiotic resistance and virulence ,which is useful for infection control .Dominant virulence genes may be the potential target for developing new vaccine to reduce S .pyogenes infection in the future .

Objective Toinvestigate the molecular characteristics including antibiotic resistance,strain type,serotype,virulence,biofilm formation of Streptococcus pneumoniae isolated from Shanghai adult patients.Methods A total of 37 non-repetitive S.pneumoniae isolates causing community acquired and hospital acquired infections of adults were collected from Shanghai Huashan Hospital from January 2011 to December 2013.The inhibitory zone diameter or minimum inhibitory concentrations (MICs) of 9 antimicrobial agents (penicillin,vancomycin,erythromycin,clindamycin,levofloxacin,cefprozi,ceftriaxone,cefotaxime and linezolid) were determined by Kirby-bauer (K-B) method or Etest method;Serotypes were tested by polymerase chain reaction (PCR) and S.pneumoniae antisera agglutination;Genomic characteristics of different serotype strains were determined by pulsed field gel electrophoresis (PFGE)method;Multilocus sequence types (MLST) was used for strain type;Semi quantitative biofilm formation test was used for the biological membrane formation.Ten main pneumococcal virulence genes (cbpA,pspA,cps2A,lytA,nana,pavA,piaA,ply,psaA and spxB) were detected by PCR and gel electrophoresis.Statistical analysis was performed using Stata software and association statistics were tested using Fisher's exact test.Results The most frequent serotypes were 19F (13.5％),23 F (13.5％),14 (10.8％),19A (10.8％).The penicillin resistance rate was 64.9％.Serotypes 19 F,19A and 23 F were significantly associated with penicillin resistance (x2 =5.89,P =0.015) and the isolates belonged to these serotypes were all multi-drug resistant (MDR).ST81 and ST271 showed high resistance rates to several antibiotics including penicillin (x2 =4.57,P =0.033).Biofilm formation was significantly associated with serotypes 19A (x2 =5.55,P =0.018) and strain type ST320 (x2 =4.33,P =0.037),but not associated with penicillin resistance (x2 =0.16,P =0.686).Virulence gene lytA,pavA,ply,psaA,spxB were found in all isolates.Conclusions Penicillin resistance rate of S.pneumoniae in adult is rising.Specific serotype,epidemic clone and antibiotic resistance are closely related,and can provide the basis for the infection control.The virulence factors such as PspA will be the new targets for vaccine development to reduce S.pneumoniae infection in the future.

Objective:To evaluate the performance of an artificial intelligent (AI)-based automated digital cell morphology analyzer (hereinafter referred as AI morphology analyzer) in detecting peripheral white blood cells (WBCs).Methods:A multi-center study. 1. A total of 3010 venous blood samples were collected from 11 tertiary hospitals nationwide, and 14 types of WBCs were analyzed with the AI morphology analyzers. The pre-classification results were compared with the post-classification results reviewed by senior morphological experts in evaluate the accuracy, sensitivity, specificity, and agreement of the AI morphology analyzers on the WBC pre-classification. 2. 400 blood samples (no less than 50% of the samples with abnormal WBCs after pre-classification and manual review) were selected from 3 010 samples, and the morphologists conducted manual microscopic examinations to differentiate different types of WBCs. The correlation between the post-classification and the manual microscopic examination results was analyzed. 3. Blood samples of patients diagnosed with lymphoma, acute lymphoblastic leukemia, acute myeloid leukemia, myelodysplastic syndrome, or myeloproliferative neoplasms were selected from the 3 010 blood samples. The performance of the AI morphology analyzers in these five hematological malignancies was evaluated by comparing the pre-classification and post-classification results. Cohen′s kappa test was used to analyze the consistency of WBC pre-classification and expert audit results, and Passing-Bablock regression analysis was used for comparison test, and accuracy, sensitivity, specificity, and agreement were calculated according to the formula.Results:1. AI morphology analyzers can pre-classify 14 types of WBCs and nucleated red blood cells. Compared with the post-classification results reviewed by senior morphological experts, the pre-classification accuracy of total WBCs reached 97.97%, of which the pre-classification accuracies of normal WBCs and abnormal WBCs were more than 96% and 87%, respectively. 2. The post-classification results reviewed by senior morphological experts correlated well with the manual differential results for all types of WBCs and nucleated red blood cells (neutrophils, lymphocytes, monocytes, eosinophils, basophils, immature granulocytes, blast cells, nucleated erythrocytes and malignant cells r>0.90 respectively, reactive lymphocytes r=0.85). With reference, the positive smear of abnormal cell types defined by The International Consensus Group for Hematology, the AI morphology analyzer has the similar screening ability for abnormal WBC samples as the manual microscopic examination. 3. For the blood samples with malignant hematologic diseases, the AI morphology analyzers showed accuracies higher than 84% on blast cells pre-classification, and the sensitivities were higher than 94%. In acute myeloid leukemia, the sensitivity of abnormal promyelocytes pre-classification exceeded 95%. Conclusion:The AI morphology analyzer showed high pre-classification accuracies and sensitivities on all types of leukocytes in peripheral blood when comparing with the post-classification results reviewed by experts. The post-classification results also showed a good correlation with the manual differential results. The AI morphology analyzer provides an efficient adjunctive white blood cell detection method for screening malignant hematological diseases.

Objective : To investigate the role of lncSIL in transforming growth factor-β1(TGF-β1)-induced alveo- lar epithelial interstitial transformation (EMT) and its related signaling pathways . Methods : Western blot was used to detect the effect of lncSIL silencing on the expression of E-cadherin ( E-cad) , alpha-smooth muscle actin ( α- SMA) and Collagen I (Col I) in the process of EMT induced by TGF-β1 . LncSIL interacting proteins were ana- lyzed by RNA pulldown . Western blot was used to detect the effect of overexpression or silencing of lncSIL on the expression of its target gene enhancer of zeste homolog 2 (EZH2) and its downstream factors P21 and cyclin-de- pendent kinase 6 (CDK6) . Flow cytometry was used to analyze the effect of lncSIL on cell cycle progression . Results: After lncSIL silencing , the expression of α-SMA and Col I increased , the expression of E-cad decreased . RNA pulldown assay showed that EZH2 was the target protein that interacted with lncSIL , and the expression of EZH2 increased after silencing lncSIL , the expression of EZH2 downstream gene P21 decreased , CDK6 increased . Flow cytometry showed that the number of cells in S phase significantly increased . When lncSIL was overexpressed , the expression of EZH2 and CDK6 was down-regulated , the expression of P21 was up-regulated , and the number of S phase cells significantly decreased . Conclusion LncSIL inhibits TGF-β1-induced alveolar epithelial cell mesen- chymal transition by negatively regulating EZH2/P21 /CDK6 signaling pathway to inhibit cell cycle progression .