ClpP affects biofilm formation of Streptococcus mutans differently in the presence of cariogenic carbohydrates through regulating gtfBC and ftf.

The abilities to form biofilms on teeth surface and to metabolize a wide range of carbohydrates are key virulence attributes of Streptococcus mutans. ClpP has been proved to play an important role in biofilm development in streptococci. Here we demonstrated that ClpP was involved in biofilm formation of S. mutans. ClpP inactivation resulted in enhanced biofilm formation or initial cell adherence in broth supplemented with sucrose, while reduced in broth supplemented with glucose or fructose. Our results also indicated that the enhanced capacities of biofilm formation and initial cell adherence were achieved through regulating the expression of a number of extracellular sucrose-metabolizing enzymes, such as glucosyltransferases (GTFB and GTFC) at early-exponential growth phase and fructosyltransferase at late-exponential growth phase in the presence of sucrose.

Contribution of ClpP to stress tolerance and virulence properties of Streptococcus mutans.

Abilities to tolerate environmental stresses and to form biofilms on teeth surface are key virulence attributes of Streptococcus mutans, the primary causative agent of human dental caries. ClpP, the chief intracellular protease of S. mutans, along with ATPases degrades altered proteins that might be toxic for bacteria, and thus plays important roles in stress response. To further understand the roles of ClpP in stress response of S. mutans, a ClpP deficient strain was constructed and used for general stress tolerance, autolysis, mutacins production, and virulence assays. Here, we demonstrated that inactivation of ClpP in S. mutans resulted in a sensitive phenotype to several environmental stresses, including acid, cold, thermal, and oxidative stresses. The ClpP deficient strain displayed slow growth rates, poor growth yields, formation of long chains, increased clumping in broth, and reduced capacity to form biofilms in presence of glucose. Mutacins production and autolysis of S. mutans were also impaired by mutation of clpP. Animals study showed that clpP mutation increased virulence of S. mutans but not significant. However, enhanced abilities to survive lethal acid and to form biofilm in sucrose were observed in ClpP deficient strain. Our findings revealed a broad impact of ClpP on several virulence properties of S. mutans and highlighted the relevance of ClpP proteolysis with progression of diseases caused by S. mutans.

Diagnostic accuracy of γ-glutamyl transpeptidase-to-platelet ratio for predicting hepatitis B-related fibrosis: a meta-analysis.

BACKGROUND AND AIM: Emerging published data on the accuracy of γ-glutamyl transpeptidase-to-platelet ratio (GPR) for diagnosing hepatitis B virus (HBV)-related fibrosis are inconsistent. The aim of this study was to systematically review the performance of GPR for diagnosing HBV-related significant fibrosis, severe fibrosis, and cirrhosis. PATIENTS AND METHODS: A comprehensive literature search of PubMed, Web of Science, and EMBASE was conducted before July 2018. Study selection was performed according to inclusion and exclusion criteria. The relevant parameters of eligible studies were abstracted. The methodological quality was assessed according to the Quality Assessment of Diagnostic Accuracy Studies. Areas under summary receiver operating characteristic curves, sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratios were used to examine the GPR accuracy for the diagnosis of significant fibrosis, severe fibrosis, and cirrhosis. RESULTS: A total of 10 studies including 5882 patients with HBV infection underwent liver biopsy were incorporated. The prevalence of significant fibrosis, severe fibrosis, and cirrhosis were 58% (range: 22-72%), 36% (range: 10-55%), and 19% (range: 2-33%), respectively. Areas under summary receiver operating characteristic curves of GPR for predicting significant fibrosis, severe fibrosis, and cirrhosis were 0.733, 0.777, and 0.796, respectively. Subgroup analysis was performed according to geographical region and histological scoring system with similar results. CONCLUSION: GPR has moderate diagnostic accuracy for predicting HBV-related significant fibrosis, severe fibrosis, and cirrhosis, and further studies with large sample size, rigorous design, multicenter study population are urgently needed.

[Diagnostic Value of MPV, PDW, PAIg and Their Combination for Megakaryocyte Dysmaturity in Children with Acute Immune Thrombocytopenic Purpura].

OBJECTIVE: To investigate the changes of mean platelet volume (MPV), platelet distribution width (PDW) and platelet associated antibodies (PAIg) in children with acute immune thrombocytopenic purpura (aITP), and to explore the diagnostic value of MPV, PDW, PAIg and their combination for megakaryocyte dysmaturity in aITP children. METHODS: Plt count, MPV and PDW of 36 aITP children were measured by using Sysmex XN automatic blood cell analyzer, and 33 children with acquired thrombocytopenic purpura (ATP) without megakaryocyte dysmaturity. The expression of PAIg was detected by flow cytometry, and the number and classification of megakaryocytes in the bone marrow were performed by marrow cytology. The diagnostic significances of MPV, PDW, PAIg and their combination as well as the sensitivity and specificity for megakaryocytes dysmaturity in aITP were assessed through calculating the area under ROC curve (AUC), after determining the influence of each parameters on the megakaryocyte dysmaturity by Logistic regression. RESULTS: MPV, PDW and PAIg of aITP children were significantly higher than those of the ATP children (P＜0.05), while the Plt count and number of thromocytogenic megakaryocytes per area (1.5 cm×3 cm) were less than those of the controls (P＜0.05). Count of RBC and WBC, percentages of neutrophil granulocytes and lymphocydes in aITP were similar to those in the controls（P＞0.05）. The results of Logistic regression showed that Plt count, MPV, PDW and PAIg were the factors influencing megakaryocyte dysmaturity in aITP children, and the regression model has a high statistical significance (χ2=65.491，P=0.001) and r square (R2=0.713). The AUC of the combined detection of Plt count, MPV, PDW and PAIg was 0.863, which was much higher than that of Plt count, MPV, PDW, PAIg individually or in pairs. The sensitivity and specificity of the combined detection were 79.167% and 89.697%, which were higher than those of Plt count, MPV, PDW, PAIg individually or in pairs. CONCLUSION: The diagnostic significance of MPV and PDW for megakaryocyte dysmaturity in aITP are insufficient, but the diagnostic efficacy can be improved by combined examination with PAIg.

[Construction of monovalent and compound nucleic acid vaccines against Toxoplasma gondii with gene encoding p30].

OBJECTIVE: To construct a monovalent gene vaccine pcDNA3.1-p30 and a compound gene vaccine pcDNA3.1-p30-ROP2 and assess the protective effect of the two vaccines against Toxoplasma gondii. METHODS: The sequences encoding p30 and ROP2 were amplified from the genomic DNA of T. gondii RH strain by polymerase chain reaction (PCR) and inserted into eukaryotic vector pcDNA3.1 to construct pcDNA3.1-p30 and pcDNA3.1-p30-ROP2. Mice were injected with the recombinant plasmid to observe the immunoprotectivity of the nucleic acid vaccine by using ELISA for detection of total IgG and observing the survival time after tachyzoites challenge. RESULTS: The recombinant plasmids pcDNA3.1-p30 and pcDNA3.1-p30-ROP2 were constructed. Mice in pcDNA3.1-p30-ROP2 group showed higher IgG (P < 0.05) and survived longer than those in pcDNA3.1-p30 group (P < 0.01) after challenged with T. gondii. CONCLUSION: Compound vaccine of genes from different stages of T. gondii elicits stronger immunoprotectivity in mice than a single gene vaccine.

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates.

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and ß-lactams. Among these isolates, 24 strains were extended-spectrum ß-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX' and aadA1 genes. ß-lactam resistance was conferred through bla SHV (22/38), bla TEM (10/38), and bla CTX-M (7/38). The highly conserved bla KPC-2 (37/38) and bla OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some isolates. Thus, we propose that both genotyping and REP-PCR typing should be used to distinguish genetic groups beyond the species level.

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through bla_SHV (22/38), bla_TEM (10/38), and bla_CTX-M (7/38). The highly conserved bla_KPC-2 (37/38) and bla_OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. ...

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through blaSHV (22/38), blaTEM (10/38), and blaCTX-M (7/38). The highly conserved blaKPC-2 (37/38) and blaOXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. ...

Multi-epitope DNA vaccine linked to the A2/B subunit of cholera toxin protect mice against Toxoplasma gondii.

The search for an effective vaccine against toxoplasmosis remains a challenging and elusive goal. Combination of epitopes from different stages of Toxoplasma gondii life cycle is an optimal strategy to overcome the antigen complexity of the parasite. Based on published epitope derived from several promising candidate vaccine antigens, we construct a DNA vaccine encoding multi-epitope of T. gondii and CpG motif, with or without the A2/B subunit of cholera toxin as a genetic adjuvant. The immunity induced by this vaccine in BALB/c mice and the protection afforded against challenge with the highly virulent RH strain of T. gondii is assessed. This vaccine was able to elicit a significant humoral and cellular immune response in vaccinated mice. Furthermore, CTXA2/B as a genetic adjuvant could enhance the magnitude of immune responses as well as increased survival rate in mice infected with the lethal RH tachyzoites. This study is the first report of a multi-epitope DNA construct strategy as a potential DNA vaccine against toxoplasmosis.