Isolation and genomic analysis of a novel bacteriophage IME278 infecting Enterobacter hormaechei and its biocontrol potential on pork.

Enterobacter hormaechei is an opportunistic pathogen and is found in a large variety of food including animal-derived food. In recent years, bacteria present a severe clinical challenge due to their increasing resistance to antibiotics. Bacteriophages have gained attention as a new antibacterial strategy. In this study, we isolated a novel E. hormaechei bacteriophage IME278 from hospital sewage in Beijing, China. Bacteriophage IME278 had a double-stranded linear DNA genome with 40,164 bp and 51.99% GC content. Whole-genome alignments showed IME278 shared 87% homology with other phages in the National Center for Biotechnology Information (NCBI) database. And phylogenetic analysis demonstrated that IME278 was highly similar to bacteriophages belonging to the genus Kayfunavirus, family Autographiviridae, indicating IME278 can be classified as a new member of the Autographiviridae family. Transmission electron microscopy revealed that IME278 had an icosahedral head 51.72 nm in diameter and a tail 151.28 nm in length. Bacteriophage IME278 was able to survive under high temperature (50 °C-70 °C) and its activity decreased significantly above 70 °C and almost completely inactivated at 80 °C. Bacteriophage IME278 could survive in a wide pH range (4.0-11.0) and it was stable in chloroform (up to 5%). The phage was sensitive to UV irradiation. Bacteriophage IME278 had a latent period of 40 min and reached a plateau stage at 150 min and its cleavage was approximately 8.21 × 108/3.66 × 108 = 2.24. The biocontrol potential of bacteriophage IME278 was evaluated in a model that artificially contaminated pork with E. hormaechei 529 and the result revealed that IME278 could effectively control bacterial contamination on pork. The in-depth analysis of the biological characteristics, whole genome sequencing, and bioinformatics of IME278 has laid the foundation for the biocontrol application and the treatment of bacteria using bacteriophages.

Serum amyloid a, C-reactive protein, and procalcitonin levels in children with Mycoplasma pneumoniae infection.

BACKGROUND: Mycoplasma pneumoniae (MP) is a common pathogen of community-acquired pneumonia in children. In the present study, serum amyloid A (SAA), C-reactive protein (CRP), and procalcitonin (PCT) levels in children with MP infection were analyzed and the differential diagnoses of MP evaluated. METHODS: The study included 152 children with MP infection hospitalized in Tai'an Central Hospital in Shandong Province and 50 healthy children as controls. SAA, CRP, and PCT, as well as serum immunoglobulins and T lymphocyte subsets were analyzed during the acute and convalescent phases. Among the MP-infected children, 30 cases were selected to monitor the SAA, immunoglobulins, and T lymphocyte subset levels for a week. RESULTS: The SAA, CRP, PCT, IgA, and IgM levels were significantly higher in the MP-infected group than in the control group (F(SAA) = 83.91, p < 0.05; F(CRP) = 40.79, p < 0.05; F(PCT) = 60.58, p < 0.05; F(IgA) = 43.45, p < 0.05; F(IgM) = 233.88, p < 0.05). In addition, the levels of these factors were significantly higher in the acute phase than in the convalescent phase (p < 0.05). However, significant difference was not observed in the IgG level between these two groups (p > 0.05). The CD3+ and CD4+ levels in the MP-infected group were lower than in the control group ( F(CD3+) = 60.58, P < 0.05; F(CD4+) = 89.05, p < 0.05), and the CD8+ level was higher than in the control group ( F(CD8+) = 96.96, p < 0.05). The CD3+ , CD4+ , and CD8+ levels were significantly different between the acute phase and the convalescent phase (CD3+ : acute phase vs. convalescent phase, q = 2.79, p < 0.05; CD4+ : acute phase vs. convalescent phase, q = 2.83, p < 0.05; CD8+ : acute phase vs. convalescent phase, q = 3.15, p < 0.05). The changes in serum SAA levels in the MP-infected group positively correlated with the changes in IgA, IgM, and CD8+ levels and negatively correlated with CD3+ , CD4+ , and CD4+ /CD8+ . CONCLUSION: SAA, CRP, and PCT were specific markers for diagnosing early MP infection in children. These findings are important in the differential diagnosis of MP infection and clinical guidance for MP treatment.

Preparation of PU/Fibrin Vascular Scaffold with Good Biomechanical Properties and Evaluation of Its Performance in vitro and in vivo.

PURPOSE: The development of tissue-engineered blood vessels provides a new source of donors for coronary artery bypass grafting and peripheral blood vessel transplantation. Fibrin fiber has good biocompatibility and is an ideal tissue engineering vascular scaffold, but its mechanical property needs improvement. METHODS: We mixed polyurethane (PU) and fibrin to prepare the PU/fibrin vascular scaffolds by using electrospinning technology in order to enhance the mechanical properties of fibrin scaffold. We investigated the morphological, mechanical strength, hydrophilicity, degradation, blood and cell compatibility of PU/fibrin (0:100), PU/fibrin (5:95), PU/fibrin (15:85) and PU/fibrin (25:75) vascular scaffolds. Based on the results in vitro, PU/fibrin (15:85) was selected for transplantation in vivo to repair vascular defects, and the extracellular matrix formation, vascular remodeling, and immune response were evaluated. RESULTS: The results indicated that the fiber diameter of the PU/fibrin (15:85) scaffold was about 712nm. With the increase of PU content, the mechanical strength of the composite scaffolds increased, however, the degradation rate decreased gradually. The PU/fibrin scaffold showed good hydrophilicity and hemocompatibility. PU/fibrin (15:85) vascular scaffold could promote the adhesion and proliferation of mesenchymal stromal cells (MSCs). Quantitative RT-PCR experimental results showed that the expression of collagen, survivin and vimentin genes in PU/fibrin (15:85) was higher than that in PU/fibrin (25:75). The results in vivo indicated the mechanical properties and compliance of PU/fibrin grafts could meet clinical requirements and the proportion of thrombosis or occlusion was significantly lower. The graft showed strong vasomotor response, and the smooth muscle cells, endothelial cells, and ECM deposition of the neoartery were comparable to that of native artery after 3 months. At 3 months, the amount of macrophages in PU/fibrin grafts was significantly lower, and the secretion of pro-inflammatory and anti-inflammatory cytokines decreased. CONCLUSION: PU/fibrin (15:85) vascular scaffolds had great potential to be used as small-diameter tissue engineering blood vessels.