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The P1 phage has garnered attention as a carrier of antibiotic resistance genes (ARGs) in Enterobacteriaceae. However, the transferability of ARGs by P1-like phages carrying ARGs, in addition to the mechanism underlying ARG acquisition, remain largely unknown. In this study, we elucidated the biological characteristics, the induction and transmission abilities, and the acquisition mechanism of the bla CTX-M-27 gene in the P1 phage. The P1-CTX phage exhibited distinct lytic plaques and possessed a complete head and tail structure. Additionally, the P1-CTX phage was induced successfully under various conditions, including UV exposure, heat treatment at 42 °C, and subinhibitory concentrations (sub-MICs) of antibiotics. Moreover, the P1-CTX phage could mobilize the bla CTX-M-27 gene into three strains of Escherichia coli ( E. coli ) and the following seven different serotypes of Salmonella : Rissen, Derby, Kentucky, Typhimurium, Cerro, Senftenberg, and Muenster. The mechanism underlying ARG acquisition by the P1-CTX phage involved Tn 1721 transposition-mediated movement of bla CTX-M-27 into the ref and mat genes within its genome. To our knowledge, this is the first report documenting the dynamic processes of ARG acquisition by a phage. Furthermore, this study enriches the research on the mechanism underlying the phage acquisition of drug resistance genes and provides a basis for determining the risk of drug resistance during phage transmission.

Carbapenem-resistant Enterobacteriaceae are some of the most important pathogens responsible for nosocomial infections, which can be challenging to treat. The bla NDM carbapenemase genes, which are expressed by New Delhi metallo-β-lactamase (NDM)-producing Escherichia coli isolates, have been found in humans, environmental samples, and multiple other sources worldwide. Importantly, these genes have also been found in farm animals, which are considered an NDM reservoir and an important source of human infections. However, the dynamic evolution of bla NDM genetic contexts and bla NDM -harboring plasmids has not been directly observed, making it difficult to assess the extent of horizontal dissemination of the bla NDM gene. In this study, we detected NDM-1 ( n = 1), NDM-5 ( n = 24), and NDM-9 ( n = 8) variants expressed by E. coli strains isolated from poultry in China from 2016 to 2017. By analyzing the immediate genetic environment of the bla NDM genes, we found that IS 26 was associated with multiple types of bla NDM multidrug resistance regions, and we identified various IS 26 -derived circular intermediates. Importantly, in E. coli strain GD33, we propose that IncHI2 and IncI1 plasmids can fuse when IS 26 is present. Our analysis of the IS 26 elements flanking bla NDM allowed us to propose an important role for IS 26 elements in the evolution of multidrug-resistant regions (MRRs) and in the dissemination of bla NDM . To the best of our knowledge, this is the first description of the dynamic evolution of bla NDM genetic contexts and bla NDM -harboring plasmids. These findings could help proactively limit the transmission of these NDM-producing isolates from food animals to humans. IMPORTANCE Carbapenem resistance in members of the order Enterobacterales is a growing public health problem that is associated with high mortality in developing and industrialized countries. Moreover, in the field of veterinary medicine, the occurrence of New Delhi metallo-β-lactamase-producing Escherichia coli isolates in animals, especially food-producing animals, has become a growing concern in recent years. The wide dissemination of bla NDM is closely related to mobile genetic elements (MGEs) and plasmids. Although previous analyses have explored the association of many different MGEs with mobilization of bla NDM , little is known about the evolution of various genetic contexts of bla NDM in E. coli. Here, we report the important role of IS 26 in forming multiple types of bla NDM multidrug resistance cassettes and the dynamic recombination of plasmids bearing bla NDM . These results suggest that significant attention should be paid to monitoring the transmission and further evolution of bla NDM -harboring plasmids among E. coli strains of food animal origin.

The aim of this study was to explore the characteristics of bla CTX-M-27 carriage and mobilization in Salmonella and Escherichia coli isolates from food-producing animals in China. A total of 2280 E. coli and 229 Salmonella isolates collected from food animals from June 2003 to September 2014 were screened for the presence of bla CTX-M-27 gene. The bla CTX-M-27 -positive isolates were typed and plasmid DNA sequenced to determine the genetic context of bla CTX-M-27 and plasmid types present. Bacterial fitness was evaluated by growth curve and plasmid stability in vitro. CTX-M-27-positive E. coli (18, 0.79 %) and Salmonella (34, 14.85 %) were detected. PFGE profiles of CTX-M-27-positive strains revealed a wide variety of genotypes and S. Indiana was the most prevalent serotype. Replicon typing, S1-PFGE and hybridization of CTX-M-27-carrying plasmids confirmed that bla CTX-M-27 gene was located on IncFII (12/18), IncN (4/18), and non-typeable (2/18) plasmids in E. coli and on P1-like bacteriophage (21/34), IncP (4/34), IncFIB (4/34), IncN (2/34), IncHI2 (2/34), and IncA/C (1/34) plasmids in Salmonella. Comparison and analysis of gene context of bla CTX-M-27 in P1-like bacteriophage and plasmids revealed they shared the same structure and contained an identical genetic context with the Tn1721-like structure ΔISEcp1B-bla CTX-M-27 -IS903D-iroN-Δmap-Tn1721. In addition, plasmid stability tests indicated that the bla CTX-M-27 P1-like bacteriophage were more stable than plasmids in the absence of cefotaxime selective pressure. These results demonstrate that Tn1721-like transposons harboring CTX-M-27 could be mobilized between different plasmids in E. coli and P1-like bacteriophage disseminated among Salmonella., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objectives: To clarify the transmission mechanism of the blaCTX-M-64 gene between Escherichia coli and Salmonella isolates from food animals., Methods: A total of 329 E. coli and 60 Salmonella isolates collected from food animals in 2016 were screened for the presence of blaCTX-M-64 genes. The blaCTX-M-64-positive isolates were typed and plasmid and chromosome DNA was sequenced to determine the genetic context of blaCTX-M-64 and the plasmid types present., Results: The blaCTX-M-64 gene was identified in only three E. coli isolates but was the predominant gene in the Salmonella isolates (n = 9). These 12 CTX-M-64-positive isolates were all resistant to ampicillin, cefotaxime, ceftiofur, ceftriaxone, ceftazidime and florfenicol and 9 were resistant to ciprofloxacin. The blaCTX-M-64 gene was located on transferable IncI2 plasmids and an IncHI2 plasmid in three E. coli and one Salmonella isolate, respectively. The remaining eight Salmonella isolates contained blaCTX-M-64 integrated into the chromosome. Different genetic contexts of blaCTX-M-64 genes were found among the 12 isolates: ISEcp1-blaCTX-M-64-orf477-A/C on IncI2 plasmids of 3 E. coli isolates; ΔISEcp1-blaCTX-M-64-orf477-A/C in the chromosome of 1 Salmonella isolate; and ISEcp1-blaCTX-M-64-orf477 on the IncHI2 plasmid and chromosome of 8 Salmonella isolates., Conclusions: To the best of our knowledge, this is the first report of chromosomally encoded CTX-M-64 in Salmonella isolates. ISEcp1-mediated transposition is likely to be responsible for the spread of blaCTX-M-64 between different plasmids and chromosomes in Enterobacteriaceae especially E. coli and Salmonella., (© The Author(s) 2020. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Although the use of expanded-criteria donors (ECDs) alleviates the problem of organ shortage, it significantly increases the incidence of delayed graft function (DGF). DGF is a common complication after kidney transplantation; however, the effect of DGF on graft loss is uncertain based on the published literature. Hence, the aim of this study was to determine the relationship between DGF and allograft survival., Methods: We conducted a retrospective, multicenter, observation cohort study. A total of 284 deceased donors and 541 recipients between February 2012 and March 2017 were included. We used logistic regression analysis to verify the association between clinical parameters and DGF, and Cox proportional hazards models were applied to quantify the hazard ratios of DGF for kidney graft loss., Results: Among the 284 deceased donors, 65 (22.8%) donors were ECD. Of the 541 recipients, 107 (19.8%) recipients developed DGF, and this rate was higher with ECD kidneys than with standard-criteria donor (SCD) kidneys (29.2% vs. 17.1%; P = 0.003). The 5-year graft survival rate was not significantly different between SCD kidney recipients with and without DGF (95.8% vs. 95.4%; P = 0.580). However, there was a significant difference between ECD kidney recipients with and without DGF (71.4% vs. 97.6%; P = 0.001), and the adjusted hazard ratio (HR) for graft loss for recipients with DGF was 1.885 (95% confidence interval [CI] = 1.305-7.630; P = 0.024). Results showed that induction therapy with anti-thymocyte globulin was protective against DGF (odds ratio = 0.359; 95% CI = 0.197-0.652; P = 0.001) with all donor kidneys and a protective factor for graft survival (HR = 0.308; 95% CI = 0.130-0.728; P = 0.007) with ECD kidneys., Conclusion: DGF is an independent risk factor for graft survival in recipients with ECD kidneys, but not SCD kidneys.

The purpose of this study was to investigate the longitudinal effects of perinatal exposure to dioxin on physical growth in a 3-year follow-up study. In 2015, 27 mother-infant pairs living in an electronic waste (e-waste) dismantling region and 35 pairs living in a control region were enrolled in the present study. Breast milk samples were collected at 4 weeks after birth. Physical growth, including weight, height, and head and chest circumferences, was measured at 6 months and 3 years of age. Dioxin levels in the breast milk were measured by gas chromatography/high-resolution mass spectrometry. Levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin and toxic equivalency values in maternal breast milk of polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and PCDDs/PCDFs were significantly higher in women residing in the e-waste dismantling region. In 3-year-old boys, inverse associations were found between height and PCDDs-TEQ. In girls, positive associations were found between height and 2,3,7,8-TetraCDD, PCDDs-TEQ, and PCDDs/PCDFs-TEQ, and for weight and PCDDs-TEQ and PCDDs/PCDFs-TEQ at 3 years of age. In this study, sex-specific differences were observed in children, in whom dioxin exposure decreased growth in boys but increased growth in girls during the first 3 years of life.

The emergence and increase in prevalence of resistance to cephalosporins amongst isolates of Salmonella from food animals imposes a public health threat. The aim of the present study was to investigate the prevalence and characteristics of CTX-M-producing Salmonella isolates from raw meat and food animals. 27 of 152 (17.76%) Salmonella isolates were ESBL-positive including 21/70 (30%) from food animals and 6/82 (7.32%) from raw meat. CTX-M-55 was the most prevalent ESBL type observed (12/27, 44.44%). 7 of 12 CTX-M-55-positive Salmonella isolates were Salmonella Indiana, 2 were Salmonella Typhimurium, 2 were Salmonella Chester, and the remaining isolate was not typeable. Eight CTX-M-55-positive Salmonella isolates were highly resistant to fluoroquinolones (MIC CIP = 64 ug/mL) and co-harbored aac(6')-Ib-cr and oqxAB . Most of the CTX-M-55 positive isolates (11/12) carried bla CTX-M-55 genes on the chromosome, with the remaining isolate carrying this gene on a transferable 280 kb IncHI2 plasmid. A chromosomal bla CTX-M-55 gene from one isolate transferred onto a 250 kb IncHI2 plasmid which was subsequently conjugated into recipient strain J53. PFGE and MLST profiles showed a wide range of strain types were carrying bla CTX-M-55 . Our study demonstrates the emergence and prevalence of foodborne Salmonella harboring a chromosomally located bla CTX-M-55 in China. The co-existence of PMQR genes with bla CTX-M-55 in Salmonella isolates suggests co-selection and dissemination of resistance to both fluoroquinolones and cephalosporins in Salmonella via the food chain in China represents a public health concern.

Myeloid-derived suppressor cells (MDSCs) are recently identified immune suppressive cells in multiple chronic inflammations. Here, we investigated MDSCs in patients with end-stage renal disease (ESRD) and their clinical significance in these patients and healthy individuals (49 each). Polymorphonuclear and mononuclear MDSCs were investigated by flow cytometry. Patients with ESRD before hemodialysis presented a significantly higher level of polymorphonuclear MDSCs. Depletion of polymorphonuclear-MDSCs resolved T cell IFN-γ responses. By co-culture, T cell proliferation and the production of IFN-γ were abrogated by the addition of polymorphonuclear MDSCs in a dose-dependent manner. Both of these effects were reversed by a reactive oxygen species inhibitor. The levels of reactive oxygen species were higher in polymorphonuclear MDSCs derived from patients with ESRD than from normal individuals. The mRNA level of NOX2, the key protein complex responsible for reactive oxygen species production, was higher in ESRD-related polymorphonuclear MDSCs. The phospho-STAT3 level, a key activator of MDSCs, was higher in ESRD-related polymorphonuclear MDSCs. Finally, the polymorphonuclear MDSC level before and after hemodialysis was positively related to infectious diseases. Patients with ESRD were dichotomized into 2 groups by the amount of polymorphonuclear MDSCs. Patients with high levels of polymorphonuclear MDSCs presented with a higher incidence of infectious events. Thus, polymorphonuclear MDSCs were elevated in ESRD patients with strong immune-suppressive capability through a phospho-STAT3/reactive oxygen species pathway. Hence, polymorphonuclear MDSCs might increase the risk of infectious complications., (Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)

Objective: To investigate the relationship of S100B protein expression and the pathogenesis of early-onset and late-onset preeclampsia., Methods: Sixty patients with preeclampsia who received caesarean section at Qingdao Municipal Hospital from October 2010 to September 2011 were enrolled in this study. Thirty cases were early-onset preeclampsia (referred as early-onset preeclampsia group, < 34 weeks), and the other 30 cases were late-onset preeclampsia (referred as late-onset preeclampsia group, ≥ 34 weeks). Thirty women who received caesarean section because of pelvic structural deformities, breech presentation, macrosomia and social factors were included as the control group. The expression of S100B mRNA in the placenta was detected by reverse transcription (RT)-PCR. The expression of S100B protein in the placenta was detected by immunohistochemistry., Results: (1) S100B mRNA was expressed in the trophoblasts of preeclampsia and control groups. The expression of S100B mRNA in early-onset preeclampsia group (0.73 ± 0.11) was significantly higher than the control group (0.58 ± 0.08) and late-onset preeclampsia group (0.64 ± 0.10, P < 0.05). There was no significant difference between late-onset preeclampsia group and the control group (P > 0.05). (2) S100B protein was expressed in the plasma membrane and cytoplasm of the trophoblasts, correlated positively with the brownish yellow and brown particles inside the cells. It was expressed in all the three groups. Immunohistochemistry revealed that the expression of S100B protein in the placenta of early-onset preeclampsia group was 100% (30/30), significantly higher than those of late-onset preeclampsia group and the control group, in which the positive rate were 70% (21/30) and 63% (19/30) respectively (P < 0.05). There was no difference between late-onset preeclampsia group and the control group (P > 0.05)., Conclusion: Early-onset and late-onset preeclampsia may have different etiology and pathogenesis. S100B may be a factor in the pathogenesis of early-onset preeclampsia.

An inhibitor of glutathione biosynthesis, buthionine sulphoximine (BSO), was used to deplete the endogenous thiols in mammalian cells in vitro. In this study, the cytotoxicity of BSO and BSO combined with the hypoxic cell radiosensitizer misonidazole (MISO) was investigated. Both aerobic and hypoxic cytotoxicity of MISO was found to be increased. The concentration of BSO required to reduce the colony forming ability to 50% (Cc) for the chronic cytotoxicity on V79 cells was 0.03 mmol/L under aerobic condition, while the Cc for the acute cytotoxicity on V79 cells under hypoxic and aerobic conditions was 0.4 and 0.5 mmol/L. The growth inhibition rate of human tumor cells K562 and SGC-7901 by BSO was 6.89-26.06% and 12.01-55.69%, respectively. Enhanced cytotoxicity activity was observed when BSO was used in combination with cis-dichlorodiamino Pt(II) or 5-fluorouracil.