Extracellular vesicles (EVs), also known as membrane vesicles, are vesicular bodies secreted by eukaryotic cells and bacteria. EVs can carry proteins, DNA, RNA, and various metabolites for the exchange and transmission of substances between cells. They play contents-dependent physiological functions, such as delivering nutrients, participating in immune response, and treating cancers. Currently, most studies focus on the exploration of vesicles secreted by eukaryotic cells and gram-negative bacteria, while few studies focus on gram-positive bacteria. This review summarized the production, content composition, physiological function, and engineering of EVs secreted by gram-positive bacteria, and prospected future perspectives in this area.
Bacteria/metabolism* ; Extracellular Vesicles/metabolism* ; Gram-Negative Bacteria ; Gram-Positive Bacteria/metabolism* ; Proteins/metabolism*

BACKGROUND: We evaluated the reliability and accuracy of the combined use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial identification and Vitek 2 antimicrobial susceptibility testing (AST) for bacteria from positive blood culture bottles. METHODS: Direct identification and AST were performed in parallel to the standard methods in monomicrobial positive blood culture bottles. In total, 254 isolates grown on aerobic and/or anaerobic bottles were identified with MALDI-TOF Vitek MS (bioMerieux, France), and 1,978 microorganism/antimicrobial agent combinations were assessed. For isolates from anaerobic bottles, an aliquot of the culture broth was centrifuged, washed, and filtered through a nylon mesh. For isolates from aerobic/pediatric bottles, a lysis step using 9.26% ammonium chloride solution and 2% saponin solution was included. RESULTS: The overall correct identification rate was 81.8% (208/254) and that for gram-positive/gram-negative isolates was 73.9%/92.6%, respectively, and it was 81.8%, 87.6%, and 57.9% for isolates from aerobic, anaerobic, and pediatric bottles, respectively. Identification was not possible in 45 cases, and most of these isolates were streptococci (N=14) and coagulase-negative staphylococci (N=11). Misidentification occurred only in one case. Compared with standard methods, direct AST showed 97.9% (1,936/1,978) agreement with very major error of 0.25%, major error of 0.05%, and minor error of 1.8%. CONCLUSIONS: This simple and cost-effective sample preparation method gives reliable results for the direct identification and AST of bacteria. For the identification of streptococci and coagulase-negative staphylococci, the method should be further improved.
Adult ; Ammonium Chloride/chemistry ; Anti-Infective Agents/*pharmacology ; Child ; Gram-Negative Bacteria/drug effects/*isolation & purification/metabolism ; Gram-Positive Bacteria/drug effects/*isolation & purification/metabolism ; Humans ; Reagent Kits, Diagnostic ; Saponins/chemistry ; *Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

This study was purposed to confirm the practical efficacy of reducing indicating germs suspended in plasma by riboflavin and photosensitized inactivation and to evaluate its influence on activation of apheresis platelet concentrates. The synergistic effects of riboflavin combined with ultraviolet irradiation on inactivation of germs were investigated by using Escherichia Coli (E. coli) and Staphylococcus Aureus (S. aureus) as Gram⁻ and Gram(+) indicating germs, respectively. The activation status of apheresis-platelet concentrates treated with riboflavin combined with ultraviolet irradiation was detected by flow cytometry. The results showed that when 50 μmol/L of riboflavin was combined with 6.2 J/ml of ultraviolet irradiation, the T/E ratios reached 1.42 for E. coli and 1.68 for S. Aureus, and reduction of E. Coli and S. Aureus were 3.87 Logs and 3.82 Logs respectively; the CD62p expression level on germ-inactivated platelets stored at 22 degrees C for 0 and 5 days were 4.92% and 36.18% respectively, which slightly increased as compared with controls (3.94% and 32.03)% (p < 0.05). It is concluded that combination of riboflavin with ultraviolet irradiation displays well synergistic effects which can reduce E. Coli and S. Aureus counts, but no significantly influence on platelets. The partial activation of liquid platelets mainly presents metabolism damage during storage, which is found at an acceptable level.
Blood Platelets ; metabolism ; Drug Carriers ; Gram-Negative Bacteria ; drug effects ; radiation effects ; Gram-Positive Bacteria ; drug effects ; radiation effects ; Humans ; P-Selectin ; blood ; Photosensitizing Agents ; pharmacology ; Platelet Count ; Plateletpheresis ; methods ; Riboflavin ; pharmacology ; Ultraviolet Rays

OBJECTIVETo investigate the antimicrobial activity of methanolic extracts of different parts of Ixora species.

METHODSAntimicrobial activity was carried out using disc diffusion assay against fungi, gram-positive and gram-negative bacteria.

RESULTSAll methanolic extracts of different parts of Ixora species showed a broad-spectrum of antibacterial and antiyeast activities, which inhibited the growth of at least one bacterium or yeast. There was no remarkable difference between different Ixora species observed in this study.

CONCLUSIONSThe significant antimicrobial activity shown by this Ixora species suggests its potential against infections caused by pathogens. The extract may be developed as an antimicrobial agent.

Anti-Bacterial Agents ; pharmacology ; Antifungal Agents ; pharmacology ; Fungi ; drug effects ; Gram-Negative Bacteria ; drug effects ; Gram-Positive Bacteria ; drug effects ; Microbial Sensitivity Tests ; Phytotherapy ; Plant Extracts ; pharmacology ; Rubiaceae ; classification ; metabolism

In previous study we isolated a gram-positive bacterial strain, designated Niu-O16, from bovine rumen gastric juice. The growing cells of bacterial strain Niu-O16 is capable of biotransforming isoflavone daidzein into dihydrodaidzein efficiently under anaerobic conditions. In this study we investigated the optimal bioconversion conditions for the resting cells of bacterial strain Niu-O16 to convert daidzein into dihydrodaidzein. Single factor test showed that the optimal conditions for the initial pH of phosphate buffer, the concentration of the resting cell and the concentration of the substrate daidzein were 6.0-8.0, 32-64 mg/mL (wet weight) and 0.8-1.2 mmol/L, respectively. Orthogonal experiments were used to determine the optimal combination of the resting cell concentration, substrate concentration and biotransformation time. The results showed that the optimal combination included resting cell concentration 32 mg/mL, substrate concentration 0.8 mmol/L and the biotransformation time 24 h. Furthermore, the biotransformation kinetics under optimal conditions were studied, under which conditions the highest bioconversion rate was 63.9% in the resting cell system. The results might provide information for resting cell biotransforming of anaerobes as well as its industrial application.
Anaerobiosis ; Animals ; Biotransformation ; Cattle ; Culture Techniques ; methods ; Gastric Juice ; microbiology ; Gram-Positive Bacteria ; growth & development ; isolation & purification ; physiology ; Isoflavones ; biosynthesis ; chemistry ; metabolism ; Kinetics ; Rumen ; microbiology

OBJECTIVEIn order to use facultative gut bacteria as an alternate to animals for the initial gastrointestinal toxicity screening of heavy metals, a comparative study on rat intestinal epithelial cells and resident gut bacteria was undertaken.

METHODSin vitro growth rate of four gut bacteria, dehydrogenase (DHA) and esterase (EA) activity test, intestinal epithelial and bacterial cell membrane enzymes and in situ effect of arsenite were analysed.

RESULTSGrowth profile of mixed resident population of gut bacteria and pure isolates of Escherichia coli, Pseudomonas sp., Lactobacillus sp., and Staphylococcus sp. revealed an arsenite (2-20 ppm) concentration-dependent inhibition. The viability pattern of epithelial cells also showed similar changes. DHA and EA tests revealed significant inhibition (40%-72%) with arsenite exposure of 5 and 10 ppm in isolated gut bacteria and epithelial cells. Decrease in membrane alkaline phosphatase and Ca2+ -Mg2+ -ATPase activities was in the range of 33%-55% in four bacteria at the arsenite exposure of 10 ppm, whereas it was 60%-65% in intestinal epithelial villus cells. in situ incubation of arsenite using intestinal loops also showed more or less similar changes in membrane enzymes of resident gut bacterial population and epithelial cells.

CONCLUSIONThe results indicate that facultative gut bacteria can be used as suitable in vitro model for the preliminary screening of arsenical gastrointestinal cytotoxic effects.

Animals ; Arsenites ; pharmacology ; Cell Membrane ; drug effects ; Culture Media ; Epithelial Cells ; drug effects ; enzymology ; microbiology ; Esterases ; metabolism ; Gram-Negative Bacteria ; drug effects ; enzymology ; growth & development ; Gram-Positive Bacteria ; drug effects ; enzymology ; growth & development ; Humans ; Intestines ; cytology ; drug effects ; microbiology ; Oxidoreductases ; metabolism ; Rats ; Teratogens ; pharmacology

BACKGROUND/AIMS: Spontaneous bacterial peritonitis (SBP) has been known to greatly influence the survival rate of patients with liver cirrhosis. However, the factors that affect the survival rate in patients with SBP need to be clarified. METHODS: This study enrolled 95 liver cirrhosis patients diagnosed with SBP. The laboratory findings of their serum and ascitic fluid were examined and the characteristics of the isolated microorganisms in their peritoneal fluid were analyzed. RESULTS: The proportion of patients with culture-positive SBP was 41.1%, and 47 microorganisms were isolated from the ascitic fluid. The proportions of cultured bacteria that were Gram negative and Gram positive were 57.4% and 40.4%, respectively. The proportions of Escherichia coli, Klebsiella species, and Streptococcus species were 25.5%, 19.1%, and 19.1%, respectively. Enterococcus species represented 12.8% of the microorganisms cultured. The overall survival rates at 6, 12, and 24 months were 44.5%, 37.4%, and 32.2%, respectively. There was no relationship between the bacterial factors and the survival rate in SBP. Multivariate analysis revealed that the presence of hepatocellular carcinoma (HCC; P=0.001), higher serum bilirubin levels (> or =3 mg/dL, P=0.002), a prolonged serum prothrombin time (i.e., international normalized ratio >2.3, P<0.001), renal dysfunction (creatinine >1.3 mg/dL, P<0.001), and lower glucose levels in the ascitic fluid (<50 mg/dL, P<0.001) were independent predictive factors of overall survival rate. CONCLUSIONS: HCC, higher serum bilirubin levels, a prolonged serum prothrombin time, renal dysfunction, and lower ascitic glucose levels are associated with higher mortality rates in cirrhotic patients with SBP.
Adult ; Aged ; Anti-Bacterial Agents/therapeutic use ; Ascitic Fluid/metabolism/microbiology ; Bilirubin/blood ; Carcinoma, Hepatocellular/complications/diagnosis ; Creatinine/blood ; Female ; Glucose/analysis ; Gram-Negative Bacteria/isolation & purification ; Gram-Positive Bacteria/isolation & purification ; Humans ; Liver Cirrhosis/complications/*mortality ; Liver Neoplasms/complications/diagnosis ; Male ; Middle Aged ; Multivariate Analysis ; Odds Ratio ; Peritonitis/complications/*diagnosis/drug therapy ; Prognosis ; Prothrombin Time ; Survival Rate

Neonatal sepsis remains one of the most important causes of death and co-morbidity in very-low-birth-weight (VLBW) infants. The aim of this study was to determine the current incidences of early-onset sepsis (EOS) and late-onset sepsis (LOS), the distribution of pathogens, and the impact of infection on co-morbidities in VLBW infants. We analyzed the data including sepsis episode from 2,386 VLBW infants enrolled in Korean Neonatal Network from January 2013 to June 2014. We defined EOS as a positive blood culture occurring between birth and 7 days of life and LOS after 7 days of life. Sepsis was found in 21.1% of VLBW infants. The risk of sepsis was inversely related to birth weight and gestational age. EOS was found in only 3.6% of VLBW infants, however the mortality rate was as high as 34.1%. EOS was associated with the increased odds for bronchopulmonary dysplasia and intraventricular hemorrhage. The vast majority of EOS was caused by Gram-positive organisms, particularly coagulase-negative staphylococci (30.6%). LOS developed in 19.4% of VLBW infants with a 16.1% mortality rate. Pathogens in LOS were dominated by coagulase-negative staphylococci (38.3%). Twenty-five percent and fifty percent of first LOS episode occurred after 12 days and 20 days from birth, respectively. Younger and smaller VLBW infants showed the earlier occurrence day for the 25% of first LOS episode. This study provides a recent nationwide epidemiology of sepsis in VLBW infants in Korea. Based on this study, successful strategies to reduce infections would improve survival and reduce morbidity.
Coagulase/metabolism ; Databases, Factual ; Gestational Age ; Gram-Negative Bacteria/isolation & purification ; Gram-Positive Bacteria/isolation & purification ; Humans ; Incidence ; Infant, Newborn ; *Infant, Very Low Birth Weight ; Kaplan-Meier Estimate ; Republic of Korea/epidemiology ; Risk Factors ; Sepsis/*epidemiology/microbiology/mortality ; Staphylococcus/enzymology/isolation & purification