Clinical characteristics, susceptibility profiles, and treatment of nocardiosis: a multicenter retrospective study in 2015-2021.

OBJECTIVES: This study aimed to investigate the microbiological characteristics, antimicrobial resistance profiles, antibiotic choice, and outcomes of Nocardia infection in various centers over a 7-year period (from 2015 to 2021). METHODS: We retrospectively analyzed the medical records of all hospitalized patients diagnosed with Nocardia between 2015 and 2021. The isolates were identified to the species level through the sequencing of 16S ribosomal RNA or secA1 or ropB genes. The susceptibility profiles were determined using the broth microdilution method. RESULTS: Of the 130 nocardiosis cases, 99 (76.2%) were established as pulmonary infection, of which the most common underlying disease was chronic lung disease (40.4%, 40/99), including bronchiectasis, chronic obstructive pulmonary disease, and chronic bronchitis. Among 130 isolates, 12 species were identified, with the most common species being Nocardia cyriacigeorgica (37.7%) and Nocardia farcinica (20.8%). All Nocardia strains were susceptible to linezolid and amikacin, and the susceptibility rate of trimethoprim-sulfamethoxazole (TMP-SMX) was 97.7%. Of the 130 patients, 86 (66.2%) received TMP-SMX monotherapy or multidrug regimen. Furthermore, 92.3% patients who were treated achieved clinical improvement. CONCLUSION: TMP-SMX was the treatment of choice for nocardiosis, and other combination drugs with TMP-SMX therapy yielded even better results.

Drug resistance analysis of Enterobacter cloacae isolated from blood samples in Hebei, 2016-2021 / 中国热带医学

@# Objective　To investigate the drug resistance of Enterobacter cloacae isolated from blood samples in 75 member units of the Bacterial Drug Resistance Monitoring Network in Hebei, 2016- 2021, so as to provide a basis for rational drug use in clinic. Methods　WHONET 5.6 software was used to retrospectively analyze drug susceptibility of Enterobacter cloacae isolated from 32 secondary hospitals and 43 tertiary hospitals. SPSS19.0 software was used for statistical analysis. Results After removing the duplicate strains, 1 225 strains of E. cloacae were isolated from blood samples of 75 hospitals during 6 years, including 157 strains from secondary hospitals and 1 068 strains from tertiary hospitals. In this study, the resistance of Enterobacter cloacae to 16 kinds of antibiotics was analyzed. The drug resistance rates to cefuroxime (52.4%-67.8%), piperacillin (27.4%-31.2%), ceftazidime (27.8%-35.5%), ceftriaxone (29.5%-45.0%), aztreonam (22.2%-32.3%), cotrimoxazole (21.6%-28.7%) were higher; the resistance rates to amikacin and tobramycin were lower than 15.0%. The resistance rates to imipenem and meropenem were 3.6%-12.3% and 5.1%-11.4%, respectively. The resistance rate to ciprofloxacin in tertiary hospitals was 22.4%, and the resistance rate to cotrimoxazole was 23.9%. Except for these two antimicrobials, the resistance rates to other antimicrobial drugs in tertiary hospitals were higher than that in secondary hospitals. A total of 121 carbapenem-resistant Enterobacter cloacae strains were detected in the past 6 years, with an increasing detection rate (χ2trend=6.305, P=0.012). Conclusions　Enterobacter cloacae has great differences in antimicrobial resistance to different antibiotics, and is sensitive to carbapenems. The drug resistance in tertiary hospitals is generally higher than that in secondary hospitals. Drug resistance monitoring and drug resistance mechanism research should be strengthened to better guide clinical drug use and curb the rise of drug resistance.

Plastid Phylogenomics of Paeonia and the Evolution of Ten Flower Types in Tree Peony.

Paeonia suffruticosa Andr., a member of Paeoniaceae, is native to China. In its 1600 years' cultivation, more than 2000 cultivars for different purposes (ornamental, medicinal and oil use) have been inbred. However, there are still some controversies regarding the provenance of tree peony cultivars and the phylogenetic relationships between and within different cultivar groups. In this study, plastid genome sequencing was performed on 10 representative tree peony cultivars corresponding to 10 different flower types. Structure and comparative analyses of the plastid genomes showed that the total lengths of the chloroplast genome of the 10 cultivars ranged from 152,153 to 152,385 bp and encoded 84-88 protein-coding genes, 8 rRNAs and 31-40 tRNAs. The number of simple sequence repeats and interspersed repeat sequences of the 10 cultivars ranged from 65-68 and 40-42, respectively. Plastid phylogenetic relationships of Paeonia species/cultivars were reconstructed incorporating data from our newly sequenced plastid genomes and 15 published species, and results showed that subsect. Vaginatae was the closest relative to the central plains cultivar group with robust support, and that it may be involved in the formation of the group. Paeonia ostii was recovered as a successive sister group to this lineage. Additionally, eleven morphological characteristics of flowers were mapped to the phylogenetic skeleton to reconstruct the evolutionary trajectory of flower architecture in Paeoniaceae.

Progress in hepatitis B virus-related acute-on-chronic liver failure treatment in China: A large, multicenter, retrospective cohort study using a propensity score matching analysis.

BACKGROUND: Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) has a high short-term mortality. However, the treatment progression for HBV-ACLF in China in the past decade has not been well characterized. The present study aimed to determine whether the HBV-ACLF treatment has significantly improved during the past decade. METHODS: This study retrospectively compared short-term (28/56 days) survival rates of two different nationwide cohorts (cohort I: 2008-2011 and cohort II: 2012-2015). Eligible HBV-ACLF patients were enrolled retrospectively. Patients in the cohorts I and II were assigned either to the standard medical therapy (SMT) group (cohort I-SMT, cohort II-SMT) or artificial liver support system (ALSS) group (cohort I-ALSS, cohort II-ALSS). Propensity score matching analysis was conducted to eliminate baseline differences, and multivariate logistic regression analysis was used to explore the independent factors for 28-day survival. RESULTS: Short-term (28/56 days) survival rates were significantly higher in the ALSS group than those in the SMT group (P < 0.05) and were higher in the cohort II than those in the cohort I (P < 0.001). After propensity score matching, short-term (28/56 days) survival rates were higher in the cohort II than those in the cohort I for both SMT (60.7% vs. 53.0%, 50.0% vs. 39.8%, P < 0.05) and ALSS (66.1% vs. 56.5%, 53.0% vs. 44.4%, P < 0.05) treatments. The 28-day survival rate was higher in patients treated with nucleos(t)ide analogs than in patients without such treatments (P = 0.046). Multivariate logistic regression analysis revealed that ALSS (OR = 0.962, 95% CI: 0.951-0.973, P = 0.038), nucleos(t)ide analogs (OR = 0.927, 95% CI: 0.871-0.983, P = 0.046), old age (OR = 1.028, 95% CI: 1.015-1.041, P < 0.001), total bilirubin (OR = 1.002, 95% CI: 1.001-1.003, P = 0.004), INR (OR = 1.569, 95% CI: 1.044-2.358, P < 0.001), COSSH-ACLF grade (OR = 2.683, 95% CI: 1.792-4.017, P < 0.001), and albumin (OR = 0.952, 95% CI: 0.924-0.982, P = 0.002) were independent factors for 28-day mortality. CONCLUSIONS: The treatment for patients with HBV-ACLF has improved in the past decade.

Carriage of Clostridioides difficile in healthy infants in the community of Handan, China: A 1-year follow-up study.

OBJECTIVE: Clostridioides difficile may colonize healthy infants and young children asymptomatically and for the long-term. C. difficile genotypes and the rate and determinants of colonization differ substantially and vary among countries and regions. A 1-year follow-up study was performed to determine the incidence, kinetics and influencing factors of C. difficile intestinal colonization. METHODS: Twenty-nine healthy infants (14 girls and 15 boys) living at home with their parents in Handan City were followed by survey from birth to 1 year of age, specifically from October 2014 through December 2015. C. difficile isolates were typed by PCR ribotyping and analyzed for the presence of toxin genes. RESULTS: During the follow-up study period in the first year of life, 20 of the 29 total enrolled infants acquired C. difficile. A total of 437 fecal samples were obtained, and 111 (25.4%) samples contained C. difficile, including 79 (71.2%) toxigenic strains. The toxigenic isolates comprised six PCR ribotypes, and two PCR ribotypes were identified as nontoxigenic strains. CONCLUSION: Our study showed that C. difficile colonization increase with age during the 12-month period, and the dominant toxigenic types of C. difficile isolates in infants were those involved in long-term colonization. Feeding patterns may affect the dynamic progress of C. difficile colonization.

Epidemiological investigation of Clostridioides difficile colonization in Chinese community infants.

Clostridioides difficile is a colonizer of the human gut; asymptomatic colonization has been reported to be more common in infants and is highly variable across regions even with no symptoms of diarrhea or death. Antibiotic treatment strategies might increase the antibiotic resistance of C. difficile. We performed a one-point study involving 1098 healthy infants (0-36 months) to address the deficiency of reports on C. difficile colonization in Chinese community infants. The C. difficile colonization rate was 22.8% (250/1098), and more than half of the strains (55.2%) were toxigenic isolates. Among the 138 toxigenic isolates, 111 were of the A+B+CDT- genotype, 26 strains were A-B+CDT-, and one strain was A+B+CDT+. Fifteen different PCR ribotypes were found among the 250 isolates, and PCR-ribotype HB03 appeared to be dominant type, accounting for 19.6% (49/250). High levels of resistance to antimicrobial agents were observed. Our study showed that age and hospitalization before stool collection were positively correlated with the C. difficile colonization rate, whereas the delivery term was negatively related to the colonization rate. Particular attention should be paid to the increasing resistance of C. difficile to rifamycin.

Enhancement of bioelectricity generation by cofactor manipulation in microbial fuel cell.

Microbial fuel cells (MFCs) are promising for harnessing bioenergy from various organic wastes. However, low electricity power output (EPT) is one of the major bottlenecks in the practical application of MFCs. In this study, EPT improvement by cofactor manipulation was explored in the Pseudomonas aeruginosa-inoculated MFCs. By overexpression of nadE (NAD synthetase gene), the availability of the intracellular cofactor pool (NAD(H/(+))) significantly increased, and delivered approximately three times higher power output than the original strain (increased from 10.86 µW/cm(2) to 40.13 µW/cm(2)). The nadE overexpression strain showed about a onefold decrease in charge transfer resistance and higher electrochemical activity than the original strain, which should underlie the power output improvement. Furthermore, cyclic voltammetry, HPLC, and LC-MS analysis showed that the concentration of the electron shuttle (pyocyanin) increased approximately 1.5 fold upon nadE overexpression, which was responsible for the enhanced electrochemical activity. Thus, the results substantiated that the manipulation of intracellular cofactor could be an efficient approach to improve the EPT of MFCs, and implied metabolic engineering is of great potential for EPT improvement.

Enhancement of bioelectricity generation by manipulation of the electron shuttles synthesis pathway in microbial fuel cells.

Microbial fuel cells (MFCs) are promising for generating bioenergy and treating organic waste simultaneously. However, low extracellular electron transfer (EET) efficiency between electrogens and anodes remains one of the major bottlenecks in practical applications of MFCs. In this paper, pyocyanin (PYO) synthesis pathway was manipulated to improve the EET efficiency in Pseudomonas aeruginosa-inoculated MFCs. By overexpression of phzM (methyltransferase encoding gene), the maximum power density of P. aeruginosa-phzM-inoculated MFC was enhanced to 166.68 µW/cm(2), which was four folds of the original strain. In addition, the phzM overexpression strain exhibited an increase of 1.6 folds in PYO production and about a onefold decrease in the total internal resistance than the original strain, which should underlie the enhancement of the EET efficiency and the electricity power output (EPT). On the basis of these results, the manipulation of electron shuttles synthesis pathways could be an efficient approach to improve the EPT of MFCs.

Preclinical transplantation and safety of HS/PCs expanded from human umbilical cord blood.

AIM: To expand hematopoietic/progenitor stem cells (HS/PCs) from umbilical cord blood (UCB) and prepare the HS/PC product, and analyze preclinical transplantation and safety of HS/PC product. METHODS: Human bone marrow-derived mesenchymal stem cells (MSCs) were used as feeder cells to expand HS/PCs from UCB in a serum-free culture system. The proliferation potential of HS/PCs was analyzed. The expanded HS/PCs were suspended in the L-15 medium to prepare the HS/PC product. The contamination of bacteria, fungi and mycoplasmas, the infection of exogenous virus, the concentration of bacterial endotoxin, and the SCF residual in HS/PC product were determined. Finally, cells from the HS/PC product with or without bone marrow-derived mesenchymal stem cells (BM-MSCs) were transplanted into the irradiated NOD/SCID mice to determine the in vivo engraftment potential. RESULTS: After co-culture for 10 d, the total nuclear cells (TNCs) increased 125-fold, and CD34(+) cells increased 43-fold. The granulocyte-macrophage colony- forming cells (GM-CFCs) and erythroid colony-forming cells (E-CFCs) increased 3.3- and 4.7-fold respectively. The expanded cells were collected and prepared as the expanded product of HS/PCs by re-suspending cells in L-15 medium. For preclinical safety, the HS/PC product was analysed for contamination by bacteria, fungi and mycoplasmas, the bacterial endotoxin concentration and the SCF content. The results showed that the HS/PC product contained no bacteria, fungi or mycoplasmas. The bacterial endotoxin concentration was less than the detection limit of 6 EU/mL, and residual SCF was 75 pg/mL. Based on clinical safety, the HS/PC product was qualified for clinical transplantation. Finally, the HS/PC product was transplanted the irradiated mice where it resulted in rapid engraftment of hematopoietic cells. CONCLUSION: HSPC product prepared from UCB in the serum-free culture system with hMSCs as feeder cells should be clinically safe and effective for clinical transplantation.

Human mesenchymal stem cells are sensitive to abnormal gravity and exhibit classic apoptotic features.

The aim of the present study was to investigate the effects of abnormal gravity on human mesenchymal stem cells (hMSCs). Strong magnetic field and magnetic field gradient generate a magnetic force that can add to or subtract from the gravitational force. In this study, this is defined as a high-magneto-gravitational environment (HMGE). The HMGE provides three apparent gravity levels, i.e. hypogravity (µg), hypergravity (2g) and normal gravity with strong magnetic field (1g) conditions. After hMSCs were subject to HMGE for 12 h, the proliferation, morphology, structure and apoptosis were investigated. Results showed that the proliferation of hMSCs was inhibited under µg condition. The abnormal gravity induced morphologic characteristics of apoptosis cells, such as cell shrinkage, membrane blebbing, nuclear chromatin condensation and margination, decreased cell viability, and increased caspase-3/7 activity. The rate of apoptosis under µg condition is up to 56.95%. The F-actin stress fibers and microtubules were disrupted under abnormal gravity condition. Under µg-condition, the expression of p53 at mRNA and protein levels was up-regulated more than 9- and 6 folds, respectively. The Pifithrin-α, an specific inhibitor of p53, inhibited the apoptosis and prevented the disruption of cytoskeleton induced by abnormal gravity. These results implied that hMSCs were sensitive to abnormal gravity and exhibited classic apoptotic features, which might be associated with p53 signaling.

Protective effect of DNA-mediated immunization with liposome-encapsulated GRA4 against infection of Toxoplasma gondii.

The dense granule protein 4 (GRA4) is a granular protein from Toxoplasma gondii, and is a candidate for vaccination against this parasite. In this study, the plasmid pcDNA3.1-GRA4 (pGRA4), encoding for the GRA4 antigen, was incorporated by the dehydration-rehydration method into liposomes composed of 16 mmol/L egg phosphatidylcholine (PC), 8 mmol/L dioleoyl phosphatidylethanolamine (DOPE), and 4 mmol/L 1,2-diodeoyl-3-(trimethylammonium) propane (DOTAP). C57BL/6 mice and BALB/c mice were immunized intramuscularly three times with liposome-encapsulated pGRA4 to determine whether DNA immunization could elicit a protective immune response to T. gondii. Enzyme-linked immunosorbent assay (ELISA) of sera from immunized mice showed that liposome-encapsulated pGRA4 generated high levels of IgG antibodies to GRA4. Production of primary interferon (IFN)-gamma and interleukin (IL)-2 in GRA4-stimulated splenocytes from vaccinated mice suggested a modulated Th1-type response. 72.7% of C57BL/6 mice immunized with liposome-encapsulated pGRA4 survived the challenge with 80 tissue cysts of ME49 strain, whereas C57BL/6 mice immunized with pGRA4 had only a survival rate of 54.5%. When immunized BALB/c mice were intraperitoneally challenged with 10(3) tachyzoites of the highly virulent RH strain, the survival time of mice immunized with liposome-encapsulated pGRA4 was markedly longer than that of other groups. Our observations show that liposome-encapsulated pGRA4 enhanced the protective effect against infection of T. gondii.

[Construction and analysis of cDNA library of Yunnan Yuanjiang O. rifupogon leaf].

The cDNA library of Yuanjiang Oryza rifupongon leaf was constructed by using SMART technology. The titers of the non-amplified library and the amplified library were 1.1 x 106 pfu/mL and 3.98 x 107 pfu/mL, respectively. The recombination rate was more than 91%. The DNA sequence length of the most cDNAs in the library was between 500-2 000 bp. Some cDNAs chosen by random were sequenced. After BLAST analysis of some cDNAs, their possible function were predicted. It is found that these cDNAs show 98% similarity to Oryza sativa japonica in the NCBI database. These provided a base for further study on the structure and function of these cDNAs and evolutionary process of Yuanjiang Oryza rifupongon.