Siderophore of hypermucoviscous promotes liver damage in mice by inducing oxidative stress.

The hypermucoviscosity/hypervirulent (hvKP) is a dominant cause of pyogenic liver abscess (PLA) and has contributed to the endemicity of disease in Asian country. The siderophore aerobactin () is highly expressed in hvKP and acting virulence role during hvKP infection. However, its role in the PLA is poorly understood.

Screening of 20 Mycobacterium tuberculosis sRNAs in plasma for detection of active pulmonary tuberculosis.

Background: Mycobacterium tuberculosis (MTB) sRNAs are abundant. However, the level of MTB sRNA in peripheral blood remains elusive.

Methods: Twenty MTB sRNAs annotated in the reference genome of H37Rv were detected in the plasma of 170 active pulmonary tuberculosis patients and 124 healthy people by qRT-PCR detection system.

Immunization With a Secreted Esterase Protects Mice Against Multiple Serotypes (M1, M3, and M28) of Group A .

Streptococcal secreted esterase (Sse) is a platelet-activating factor acetylhydrolase that is critical for Group A (GAS) skin invasion and innate immune evasion. There are two Sse variant complexes that share >98% identity within each complex but display about 37% variation between the complexes in amino acid sequences. Sse immunization protects mice against lethal infection and skin invasion in subcutaneous infection with the hypervirulent CovRS mutant strain, MGAS5005.

Detection of mycobacterial small RNA in the bacterial culture supernatant and plasma of patients with active tuberculosis.

Bacterial small RNA (sRNA) has been shown to play an important role in control of bacteria virulence, stress response and physiological metabolism by post-transcriptional regulation of gene expression. However, there were few reports about bacterial sRNA as a biomarker of infection. To test the potential role of sRNA in indicating infection of Mycobacterium tuberculosis, total RNA were extracted from the filtrated bacterial cultural supernatant.

Siderophores in clinical isolates of Klebsiella pneumoniae promote ciprofloxacin resistance by inhibiting the oxidative stress.

To explore the relevance of and understand the potential mechanisms behind the production of siderophores by clinical isolates of K. pneumoniae and ciprofloxacin (CIP) resistance, we divided the K. pneumoniae isolates into two groups based on bacterial siderophores production: high siderophore-yielding group (39 strains) and low siderophore-yielding group (38 strains).

Peroxiredoxin 1 Contributes to Host Defenses against Mycobacterium tuberculosis.

Peroxiredoxin (PRDX)1 is an antioxidant that detoxifies hydrogen peroxide and peroxinitrite. Compared with wild-type (WT) mice, Prdx1-deficient (Prdx1) mice showed increased susceptibility to Mycobacterium tuberculosis and lower levels of IFN-γ and IFN-γ-producing CD4 T cells in the lungs after M. tuberculosis infection.

Synergistic effects of baicalein with cefotaxime against Klebsiella pneumoniae through inhibiting CTX-M-1 gene expression.

Background: Generation of extended- spectrum β- lactamases is one of the major mechanisms by which clinical Klebsiella pneumoniae develop resistance to antibiotics. Combined antibiotics prove to be a relatively effective method of controlling such resistant strains. Some of Chinese herbal active ingredients are known to have synergistic antibacterial effects.

Multilocus Sequence Types and Virulence Determinants of Hypermucoviscosity-Positive Klebsiella pneumoniae Isolated from Community-Acquired Infection Cases in Harbin, North China.

We investigated the molecular epidemiologic characteristics and virulence of hypermucoviscosity-positive Klebsiella pneumoniae in mainland China. We detected 16 hypermucoviscosity-positive strains in 65 total clinical isolates (24.62%).

Use of antibiotics by urban and rural residents in Heilongjiang Province, China: cross-sectional study.

Objective: To identify and compare the factors affecting the knowledge of, attitude towards and use of antibiotics between urban and rural residents in China.

Methods: A total of 3631 urban and rural residents in Heilongjiang Province, China, were selected using random sampling. Questionnaires recorded demographic characteristics and participant knowledge of, attitude towards and use of antibiotics.

Development of a multiplex PCR system and its application in detection of blaSHV, blaTEM, blaCTX-M-1, blaCTX-M-9 and blaOXA-1 group genes in clinical Klebsiella pneumoniae and Escherichia coli strains.

Resistance to β-lactam antibiotics through β-lactamase production by Enterobacteriaceae continues to burden the health-care sector worldwide. Traditional methods for detection of β-lactamases are time-consuming and labor-intensive and newer methods with varying capabilities continue to be developed. The objective of this study was to develop a multiplex PCR (M-PCR) system for the detection of blaSHV, blaTEM, blaCTX-M-1, blaCTX-M-9 and blaOXA-1 group genes and to apply it in clinical Klebsiella pneumoniae and Escherichia coli strains.

Colloidal gold-based immunochromatographic strip test compromising optimised combinations of anti-S. suis capsular polysaccharide polyclonal antibodies for detection of Streptococcus suis.

A rapid diagnosis kit that detects Streptococcus suis (S. suis) antigens from urine with an immunochromatographic stripe (ICS) test was developed in this study. The ICS test was produced using colloidal gold coated with polyclonal antibodies (pAbs) against S.

Intranasal immunization with a mixture of PspA and a Toll-like receptor agonist induces specific antibodies and enhances bacterial clearance in the airways of mice.

To develop an effective nasal vaccine for Streptococcus pneumoniae, the effects of a panel of Toll-like receptor (TLR) agonists in combination with pneumococcal surface protein A (PspA) on induction of PspA-specific antibodies and bacterial clearance were compared in mice. Mice were nasally immunized with 10 microg of TLR agonist (TLR 2-4 and 9) and 2.5 microg of PspA once per week for 3 weeks.

Positive correlation between low adhesion of group A Streptococcus to mammalian cells and virulence in a mouse model.

We previously reported that a mouse model reflected, at least in part, the pathogenic mechanism of bacteremia observed during streptococcal toxic shock syndrome caused by group A Streptococcus (GAS). We have extended this study by assaying the in vitro adhesion of these same isolates to mammalian cells. Unexpectedly, we found that high-virulence GAS isolates in the mouse model showed low adhesion to the host cells.

Cloning, expression, and characterization of the superantigen streptococcal pyrogenic exotoxin G from Streptococcus dysgalactiae.

We identified seven novel variants of streptococcal pyrogenic exotoxin G (SPEGG), a superantigen, in Streptococcus dysgalactiae subsp. dysgalactiae or equisimilis isolates from clinical cases of infection in humans and animals. Phylogenetic analysis of the SPEGG variants indicated two clades in the dendrogram: one composed of variants derived from the bacteria isolated from the humans and the other composed of variants from the bacteria isolated from the animals.

Strain-specific pulmonary defense achieved after repeated airway immunizations with non-typeable haemophilus influenzae in a mouse model.

Strain-specific immune responses may play a critical role in the acute exacerbation of chronic obstructive pulmonary disease (COPD) caused by Haemophilus influenzae (NTHi), and the outer membrane protein P2 is one of surface antigens of NTHi, which may contribute to the strain-specific protective immunity. We examined whether repeated airway immunizations with killed-NTHi strains bearing different P2 molecules were capable of inducing protective immunity against homologous or heterologous strains in the lungs of a mouse model. Three different strains of NTHi were used in this study.

Cytocidal effect of Streptococcus pyogenes on mouse neutrophils in vivo and the critical role of streptolysin S.

We analyzed the in vivo dynamics of peritoneal exudate cells (PECs) in mice injected with group A streptococcus (GAS). A live low-virulence strain, as well as heat-killed low- and high-virulence strains, significantly increased the number of PECs (primarily neutrophils), whereas a live high-virulence strain did not. When coinjected with thioglycollate, the live high-virulence strain, as well as most other GAS strains, suppressed the ability of thioglycollate to induce neutrophil exudation.

Quantitative and qualitative comparison of virulence traits, including murine lethality, among different M types of group A streptococci.

Epidemiological studies have proposed an association between group A streptococci (GAS) bearing a particular M serological type and pathologic conditions such as streptococcal toxic shock syndrome (STSS). M1 and M3 GAS are isolated from STSS cases more frequently, whereas M4 and M12 GAS are isolated from non-STSS cases more frequently. To investigate whether there is any difference contributing the M-type association among GAS, we compared various virulence traits, including the murine lethality of M4, M12, M1, and M3 GAS clinical isolates, which are not clonally related to one another.

Streptococcus dysgalactiae-derived mitogen (SDM), a novel bacterial superantigen: characterization of its biological activity and predicted tertiary structure.

A mitogenic substance, designated Streptococcus dysgalactiae-derived mitogen (SDM), was purified from S. dysgalactiae culture supernatant, and the gene encoding the mitogen was cloned. Both native and recombinant SDM expressed in Escherichia coli significantly activated human V beta 1+ and V beta 23+ T cells in association with major histocompatibility complex (MHC) class II molecules on accessory cells, indicating that SDM possesses superantigenic properties.