Burkholderia cepacia infection in children without cystic fibrosis: a clinical analysis of 50 cases.

Background: Burkholderia cepacia (B. cepacia) is an emerging pathogen of nosocomial infection in pediatric patient carrying cystic fibrosis. The clinical diagnosis and treatment of B. cepacia infection remains poorly studied. This study outlined the risk factors, antimicrobial susceptibility, and clinical characteristics aiming to improve the treatment of B. cepacia infection. Methods: A retrospective study was conducted based on the 50 cases infection caused by B. cepacia in children without cystic fibrosis, which were diagnosed in the First Affiliated Hospital of Xiamen University, from January 1st, 2011 to December 31st, 2021. Results: A total of 50 children were infected with B. cepacia, of whom 68% had an underlying health condition, such as cardiovascular disease (23.5%), respiratory disease (17.6%), nervous system disease (14.7%), and neoplastic disease (14.7%). At the onset of B. cepacia infection, 42 (84%) pediatric patients were in an intensive care unit (ICU), 33 (66%) underwent endotracheal intubation, and 32 (64%) had a central venous catheter (CVC). In addition, hospital-acquired cases were 46 (92%), and healthcare-acquired cases were 4 (12%). The most common infectious sites of B. cepacia were the respiratory tract (68%), followed by the blood (20%), and the urinary tract (12%). It indicated that B. cepacia was the most sensitive to ceftazidime (95.65%), followed by trimethoprim-sulfamethoxazole (88.68%), meropenem (82.98%), cefepime (77.78%), and levofloxacin (55.85%). The drug resistance rate of piperacillin-tazobactam, minocycline, aztreonam, cefoperazone-sulbactam and ceftriaxone was higher than 55%. 38 cases were cured or improved, eight had treatment terminated, and four died. Conclusion: B. cepacia is an opportunistic pathogen normally found in immunocompromised pediatric patients and highly likely to lead to drug resistance. Nosocomial B. cepacia infections occurred mostly in patients in the ICU based on our observations. The surveillance of B. cepacia infections including changing epidemiology and increasing resistance of the microorganism is still very important. Treatment with effective antibiotics such as ceftazidime, meropenem, trimethoprim-sulfamethoxazole is associated with a favorable prognosis.

An Investigation of the Properties of Expanded Polystyrene Concrete with Fibers Based on an Orthogonal Experimental Design.

Expanded polystyrene (EPS) concrete is commonly used as the core material of commercial sandwich panels (CSPs). It is environmentally friendly and lightweight but has poor strength. Adding fibers can improve the microstructure of EPS concrete and reduce the weakening effect of EPS beads on the mechanical properties of concrete. An orthogonal experimental design (OED) was used in this paper to analyze the influence of length and content of polypropylene fiber (PF), glass fiber (GF), and carbon fiber (CF) on the physical and mechanical properties and micromorphology of EPS concrete. Among them, CFs have the most apparent impact on concrete and produce the most significant improvements in all properties. According to the requirements of the flexural performance of CSPs, the splitting tensile strength was taken as the optimization index, and the predicted optimal combination (OC) of EPS concrete with fibers was selected. The variations in the material properties, mechanical properties, and microstructure with age were analyzed. The results show that with increasing age, the dry density, compressive strength, and splitting tensile strength of concrete are markedly improved relative to those of the CSP core material and the control case (CC), and even the degree of hydration is improved.

Development of an immunochromatographic test strip for the rapid detection of aristolochic acid A in herbal medicinal materials.

INTRODUCTION: Plants containing aristolochic acid and its derivatives are nephrotoxic, mutagenic, and carcinogenic to humans; chronic diet poisoning caused by the aristolochic acid is the cause of endemic (Balkan) nephropathy and related cancers. OBJECTIVE: To develop a colloidal gold immunochromatographic test strip (ICS) based on the competitive format for the rapid detection of aristolochic acid A (AA-A) in herbal medicinal materials. MATERIALS AND METHODS: For the ICS based on gold nanoparticles (AuNPs), the antigen [AA-A-bovine serum albumin (BSA)], and goat anti-mouse IgG were drawn on the nitrocellulose membrane as the test line (T line) and the control line (C line), respectively. Monoclonal antibody (MAb)-AuNP conjugates were sprayed onto the conjugate pad. The sensitivity of the ICS was 6 ng/mL, and the test was completed in 10 min. The analysis of AA-A in traditional Chinese medicine samples showed that the ICS results were in good agreement with those obtained by high-performance liquid chromatography methods. CONCLUSION: These results demonstrated that the ICS test could be used as a reliable, rapid, cost-effective, and convenient qualitative tool for on-site screening techniques to detect AA-A in herbal medicinal materials without any special instrumentation.

A Green Route for High-Yield Production of Tetramethylpyrazine From Non-Food Raw Materials.

2,3,5,6-Tetramethylpyrazine (TMP) is an active pharmaceutical ingredient originally isolated from Ligusticum wallichii for curing cardiovascular and cerebrovascular diseases and is widely used as a popular flavoring additive in the food industry. Hence, there is a great interest in developing new strategies to produce this high-value compound in an ecological and economical way. Herein, a cost-competitive combinational approach was proposed to accomplish green and high-efficiency production of TMP. First, microbial cell factories were constructed to produce acetoin (3-hydroxy-2-butanone, AC), an endogenous precursor of TMP, by introducing a biosynthesis pathway coupled with an intracellular NAD+ regeneration system to the wild-type Escherichia coli. To further improve the production of (R)-AC, the metabolic pathways of by-products were impaired or blocked stepwise by gene manipulation, resulting in 40.84 g/L (R)-AC with a high optical purity of 99.42% in shake flasks. Thereafter, an optimal strain designated GXASR11 was used to convert the hydrolysates of inexpensive feedstocks into (R)-AC and achieved a titer of 86.04 g/L within 48 h in a 5-L fermenter under optimized fermentation conditions. To the best of our knowledge, this is the highest (R)-AC production with high optical purity (≥98%) produced from non-food raw materials using recombinant E. coli. The supernatant of fermentation broth was mixed with diammonium phosphate (DAP) to make a total volume of 20 ml and transferred to a high-pressure microreactor. Finally, 56.72 g/L TMP was obtained in 3 h via the condensation reaction with a high conversion rate (85.30%) under optimal reaction conditions. These results demonstrated a green and sustainable approach to efficiently produce high-valued TMP, which realized value addition of low-cost renewables.

Enhanced production of optical (S)-acetoin by a recombinant Escherichia coli whole-cell biocatalyst with NADH regeneration.

Acetoin is an important platform chemical with a variety of applications in foods, cosmetics, chemical synthesis, and especially in the asymmetric synthesis of optically active pharmaceuticals. It is also a useful breath biomarker for early lung cancer diagnosis. In order to enhance production of optical (S)-acetoin and facilitate this building block for a series of chiral pharmaceuticals derivatives, we have developed a systematic approach using in situ-NADH regeneration systems and promising diacetyl reductase. Under optimal conditions, we have obtained 52.9 g L-1 of (S)-acetoin with an enantiomeric purity of 99.5% and a productivity of 6.2 g (L h)-1. The results reported in this study demonstrated that the production of (S)-acetoin could be effectively improved through the engineering of cofactor regeneration with promising diacetyl reductase. The systematic approach developed in this study could also be applied to synthesize other optically active α-hydroxy ketones, which may provide valuable benefits for the study of drug development.