BACKGROUND: We evaluated the performance of the BD MAX StaphSR Assay (SR assay; BD, USA) for direct detection of Staphylococcus aureus and methicillin resistance not only in S. aureus but also in coagulase-negative Staphylococci (CNS) from positive blood cultures. METHODS: From 228 blood culture bottles, 103 S. aureus [45 methicillin-resistant S. aureus (MRSA), 55 methicillin-susceptible S. aureus (MSSA), 3 mixed infections (1 MRSA+Enterococcus faecalis, 1 MSSA+MRCNS, 1 MSSA+MSCNS)], and 125 CNS (102 MRCNS, 23 MSCNS) were identified by Vitek 2. For further analysis, we obtained the cycle threshold (Ct) values from the BD MAX system software to determine an appropriate cutoff value. For discrepancy analysis, conventional mecA/mecC PCR and oxacillin minimum inhibitory concentrations (MICs) were determined. RESULTS: Compared to Vitek 2, the SR assay identified all 103 S. aureus isolates correctly but failed to detect methicillin resistance in three MRSA isolates. All 55 MSSA isolates were correctly identified by the SR assay. In the concordant cases, the highest Ct values for nuc, mecA, and mec right-extremity junction (MREJ) were 25.6, 22, and 22.2, respectively. Therefore, we selected Ct values from 0-27 as a range of positivity, and applying this cutoff, the sensitivity/specificity of the SR assay were 100%/100% for detecting S. aureus, and 97.9%/98.1% and 99.0%/95.8% for detecting methicillin resistance in S. aureus and CNS, respectively. CONCLUSIONS: We propose a Ct cutoff value for nuc/mec assay without considering MREJ because mixed cultures of MSSA and MRCNS were very rare (0.4%) in the positive blood cultures.
Anti-Bacterial Agents/pharmacology ; Bacteremia/diagnosis/microbiology ; Coagulase/metabolism ; Humans ; Methicillin-Resistant Staphylococcus aureus/drug effects/genetics/*isolation & purification ; Microbial Sensitivity Tests ; Oxacillin/pharmacology ; Reagent Kits, Diagnostic ; Staphylococcus/drug effects/enzymology/genetics/isolation & purification ; Staphylococcus aureus/drug effects/genetics/*isolation & purification

Peptide cyclization, a pivotal approach to modifying linear precursors of proteins and pepticles, has been used to enhance their biological activities and serum stabilities. Recently, sortase A (SrtA) from Staphyloccus aureus becomes a promising new technology for efficiently incorporating site specific modifications into proteins, conjugating the cell surface and cyclizing the linear peptides. In this study, we constructed two recombinant expression systems, one with chitin binding domain and the other with six-histidine tag and chitin binding domain on the N-terminal of SrtA, separately. The results of enzymatic kinetics indicate that the two recombinant tags do not impair the transpeptidase activity of SrtA compared with the standard reaction reported under the same reaction condition. The two synthesized peptides with N-ternimal three glycines and C-terminal penta-amino acid motif, LPETG, were cyclized using immobilized and recycled SrtA. The SrtA-based cyclization promises to represent a simple method for easy and efficient enzymatic synthesis of large cyclic peptides.
Aminoacyltransferases ; metabolism ; Bacterial Proteins ; metabolism ; Cyclization ; Cysteine Endopeptidases ; metabolism ; Enzymes, Immobilized ; metabolism ; Kinetics ; Peptides ; metabolism ; Peptides, Cyclic ; biosynthesis ; Staphylococcus aureus ; enzymology

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

A N-acetylneuraminate lyase gene (shnal) from Staphylococcus hominis was cloned into pET-28a and expressed in Escherichia coli BL21 (DE3) host cells. The recombinant enzyme was purified and characterized. It is a homotetrameric enzyme with the optimum pH at 8.0 for the cleavage direction and the optimum pH and temperature were 7.5 and 45 degrees C for the synthetic direction. The activity of ShNAL is stable when incubated at 45 degrees C for 2 h but decreased rapidly over 50 degrees C. ShNAL showed high stability in a wide range pH from 5.0 to 10.0 with the residual activity being > 70% when the enzyme was incubated in different buffers at 4 degrees C for 24 h. Its K(m) towards N-acetylneuraminic acid, pyruvate and ManNAc were (4.0 +/- 0.2) mmol/L, (35.1 +/- 3.2) mmol/L and (131.7 +/- 12.1) mmol/L, respectively. The k(cat)/K(m) value of Neu5Ac, ManNAc, and Pyr for ShNAL were 1.9 L/(mmol x s), 0.08 L/(mmol x s) and 0.08 L/(mmol x s), respectively.
Bacterial Proteins ; genetics ; metabolism ; Cloning, Molecular ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Hydrogen-Ion Concentration ; Oxo-Acid-Lyases ; genetics ; metabolism ; Recombinant Proteins ; genetics ; metabolism ; Staphylococcus hominis ; enzymology ; Temperature

No abstract available.
Acute Disease ; Adolescent ; Alkaline Phosphatase/*blood ; Anti-Bacterial Agents/*therapeutic use ; Arthritis, Infectious/*drug therapy/*enzymology/microbiology ; *Bacterial Infections/drug therapy/enzymology/microbiology ; Child ; Child, Preschool ; Haemophilus influenzae type b/isolation & purification ; Humans ; Infant ; Osteomyelitis/*drug therapy/*enzymology/microbiology ; Staphylococcus aureus/isolation & purification ; Streptococcus pneumoniae/isolation & purification ; Streptococcus pyogenes/isolation & purification

We established a rapid detection method of New Delhi Metallo-beta-Lactamase Gene (NDM-1) based on Loop-mediated Isothermal Amplification (LAMP). With the application of LAMP, we designed four sets of LAMP premiers, using NDM-1 gene as the target sequence, and selected the set of optimal primers. Meanwhile, we established optimal reaction systems and conditions to carry out the sensitivity and specificity experiments. The experiment results showed that the whole detection process took only one hour and could be observed visually. In the experiment of sensitivity, NDM-1 gene had a detection limit of 6 copies in each reaction. In the experiment of specificity, we detected NDM-1 gene in 4 pathogen strains (Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae), and the total DNA from intestinal microbes and the total DNA from soil microbes. We had not detected the amplification reactions. The detection method established could rapidly detect NDM-1 gene and visualize the experiment result. The method is easy to operate and has high sensitivity and specificity and thus has great application value in basic research laboratories, emergent detection and spot detection.
Bacteria ; enzymology ; genetics ; Bacteriological Techniques ; methods ; DNA, Bacterial ; genetics ; Escherichia coli ; enzymology ; genetics ; Klebsiella pneumoniae ; enzymology ; genetics ; Nucleic Acid Amplification Techniques ; methods ; Sensitivity and Specificity ; Staphylococcus aureus ; enzymology ; genetics ; Streptococcus pneumoniae ; enzymology ; genetics ; beta-Lactamases ; genetics

BACKGROUNDGram-positive bacteria such as Staphylococcus aureus have been a common cause of infection among liver transplant (LT) recipients in recent decades. The understanding of local epidemiology and its evolving trends with regard to pathogenic spectra and antibiotic susceptibility is beneficial to prophylactic and empiric treatment for LT recipients. This study aimed to investigate etiology, timing, antibiotic susceptibility and risk factors for multidrug resistant (MDR) Gram-positive coccal bacteremia after LT.

METHODSA cohort analysis of prospectively recorded data was performed to investigate etiologies, timing, antibiotic susceptibility and risk factors for MDR Gram-positive coccal bacteremia in 475 LT recipients.

RESULTSIn 475 LT recipients in the first six months after LT, there were a total of 98 episodes of bacteremia caused by Gram-positive cocci in 82 (17%) patients. Seventy-five (77%) bacteremic episodes occurred in the first post-LT month. The most frequent Gram-positive cocci were methicillin-resistant coagulase-negative staphylococcus (CoNS, 46 isolates), methicillin-resistant Staphylococcus aureus (MRSA, 13) and enterococcus (34, E. faecium 30, E. faecalis 4). In all Gram-positive bacteremic isolates, 59 of 98 (60%) were MDR. Gram-positive coccal bacteremia and MDR Gram-positive coccal bacteremia predominantly occurred in patients with acute severe exacerbation of chronic hepatitis B and with fulminant/subfulminant hepatitis. Four independent risk factors for development of bacteremia caused by MDR Gram-positive coccus were: LT candidates with encephalopathy grades II - IV (P = 0.013, OR: 16.253, 95%CI: 1.822 - 144.995), pre-LT use of empirical antibiotics (P = 0.018, OR: 1.029, 95%CI: 1.002 - 1.057), post-LT urinary tract infections (P < 0.001, OR: 20.340, 95%CI: 4.135 - 100.048) and abdominal infection (P = 0.004, OR: 2.820, 95%CI: 1.122 - 10.114). The main infectious manifestations were coinfections due to gram-positive cocci and gram-negative bacilli.

CONCLUSIONSMethicillin-resistant CoNS and enterococci are predominant pathogens among LT recipients with Gram-positive coccal bacteremia. Occurrences of Gram-positive coccal bacteremia may be associated with the severity of illness in the perioperative stage.

Anti-Bacterial Agents ; pharmacology ; Bacteremia ; etiology ; microbiology ; Coagulase ; metabolism ; Drug Resistance, Multiple, Bacterial ; Enterococcus ; drug effects ; enzymology ; physiology ; Gram-Positive Bacterial Infections ; enzymology ; microbiology ; transmission ; Humans ; Liver Diseases ; microbiology ; Liver Transplantation ; adverse effects ; Risk Factors ; Staphylococcal Infections ; enzymology ; microbiology ; transmission ; Staphylococcus ; drug effects ; enzymology ; physiology

OBJECTIVETo study the active compounds from the rhizomes of Musa basjoo.

METHODAntioxidant and alpha-glucosidase inhibitory activity of different extracts were tested. Using bioassay-guided fractionation, the chemical constituents in EtOAC extracts were isolated by column chromatography and identified by MS and NMR spectroscopy.

RESULTFive compounds were isolated and identified as 2',3, 4'-trihydroxyflavone (1), 3,3'-bis-hydroxyanigorufone (2), irenolone (3), 4-dihydroxy-9-(4'-hydroxyphenyl)-phenalenone (4) and 3,4-dihydroxybenzaldehyde (5). Compound 1(IC50 8.61 mg x L(-1)), 3 (IC50 19.55 mg x L(-1)) and 5 (IC50 1.1 mg x L(-1)) had antioxidant activity. Compound 2 (IC50 24.15 mg x L(-1)) and 4(IC50 2.81 mg x L(-1)) had alpha-glucosidase inhibitory activity. Compound 5 showed MIC of 0.078, 0.313, 0.039 microg/disc against SA, MRSA and ESBLs, respectively.

CONCLUSIONCompound 1-5 were isolated from this plant for the first time. Compound 5 was isolated from the genus Musa for the first time. All compound except 5 were first reported about activity.

Bacterial Proteins ; analysis ; antagonists & inhibitors ; Enzyme Inhibitors ; analysis ; isolation & purification ; pharmacology ; Glycoside Hydrolase Inhibitors ; Musa ; chemistry ; Plant Extracts ; analysis ; isolation & purification ; pharmacology ; Rhizome ; chemistry ; Staphylococcus aureus ; drug effects ; enzymology ; alpha-Glucosidases ; analysis

Necrotizing fasciitis (NF) is a deep infection of the subcutaneous tissue that progressively destroys fascia and fat; it is associated with systemic toxicity, a fulminant course, and high mortality. NF most frequently develops from trauma that compromises skin integrity, and is more common in patients with predisposing medical conditions such as diabetes mellitus, atherosclerosis, alcoholism, renal disease, liver disease, immunosuppression, malignancy, or corticosteroid use. Most often, NF is caused by polymicrobial pathogens including aerobic and anaerobic bacteria. NF caused by Staphylococcus aureus as a single pathogen, however, is rare. Here we report a case of NF that developed in a healthy woman after an isolated shoulder sprain that occurred without breaking a skin barrier, and was caused by Staphylococcus aureus as a single pathogen.
*Arm ; Coagulase/metabolism ; Fasciitis, Necrotizing/*etiology/microbiology/pathology/surgery ; Female ; Humans ; Middle Aged ; Shoulder Joint/*injuries ; Sprains and Strains/*complications ; Staphylococcal Infections/*etiology/microbiology ; Staphylococcus aureus/enzymology/isolation & purification

Lipases are important biocatalysts that are widely used in food processing and bio-diesel production. However, organic solvents could inactivate some lipases during applications. Therefore, the efficient cloning and expression of the organic solvent-tolerant lipase is important to its application. In this work, we first found out an organic solvent-tolerant lipase from Staphylococcus saprophyticus M36 and amplified the 741 bp Lipase gene lip3 (GenBank Accession No. FJ979867), by PCR, which encoded a 31.6 kD polypeptide of 247 amino acid residues. But the lipase shared 83% identity with tentative lip3 gene of Staphylococcus saprophyticus (GenBank Accession No. AP008934). We connected the gene with expression vector pET-DsbA, transformed it into Escherichia coli BL21 (DE3), and obtained the recombinant pET-DsbA-lip3. With the induction by 0.4 mmol/L of isopropyl beta-D-thiogalactopyranoside at pH 8.0, OD600 1.0, 25 degrees C for 12 h, the lipase activity reached up to 25.8 U/mL. The lipase expressed was stable in the presence of methanol, n-hexane, and isooctane, n-heptane.
Amino Acid Sequence ; Base Sequence ; Cloning, Molecular ; Enzyme Stability ; Escherichia coli ; genetics ; metabolism ; Lipase ; biosynthesis ; genetics ; Molecular Sequence Data ; Organic Chemicals ; chemistry ; Recombinant Proteins ; biosynthesis ; genetics ; Solvents ; chemistry ; Staphylococcus saprophyticus ; enzymology