Dissemination of carbapenem-non-susceptible Acinetobacter baumannii isolates collected from educational hospitals in Qazvin province of Iran

Background:Acinetobacter baumannii(A.baumannii)is known as an opportunistic pathogen related to health-care-associated infection that has a high antibiotic resistance potential,notably against carbapenems that are widely used to combat A.baumannii infections.This study aimed to detect oxacillin-hydrolyzing(OXA)carbapenemases and metallo-β-lactamases(MBL)among carbapenem-resistant A.baumannii isolated strains and to determine their clonal relationship by repetitive extragenic palindromic PCR(rep-PCR).Methods:In the present study,a total of 211 non-repetitive isolates of A.baumannii were collected from Qazvin educational hospitals(2016–2017).The disk diffusion method was used to investigate the antibiotic susceptibility of studied strains,followed by the detection of MBL and OXA-type genes using polymerase chain reaction(PCR)and sequencing methods.The rep-PCR method assessed the clonal relationship of carbapenem-non-susceptible A.baumannii isolates.Result:The obtained results showed that 87.2%and 86.7%of isolates were non-susceptible to imipenem and meropenem.The blaOXA-24(93.5%)was the most frequent gene,followed by the blaOXA-23(4.34%),blaIMP-1(1.63%),and blaVIM-1(0.54%).Meanwhile,blaOXA-58 and blaOXA-143 genes were not found.81.5%and 66.1%of isolates contained ISAba1 upstream of the blaOXA-23 and blaOXA-58 genes,respectively.Rep-PCR results revealed the carbapenem non-susceptible isolates belonged to three distinct clones:A 171(81%),B 34(16.1%),and C 6(2.8%).Conclusions:The results indicated a high prevalence of carbapenem-non-susceptible A.baumannii,with the emergence of the blaOXA-24 gene as the most common gene and the notable prevalence of MBL genes.These results revealed the need for appropriate therapeutic and infection control strategies and monitoring susceptibility patterns for controlling A.baumannii infections.

Characterization of 1-Aminocyclopropane-1-Carboxylate(ACC) Deaminase-Containing Pseudomonas spp.in the Rhizosphere of Salt-Stressed Canola

When exposed to biotic or abiotic stress conditions, plants produce ethylene from its immediate precursor 1-aminocyclopropane-1- carboxylate （ACC）, leading to retarded root growth and senescence. Many plant growth-promoting rhizobacteria contain the enzyme ACC deaminase and this enzyme can cleave ACC to form a-ketobutyrate and ammonium, thereby lowering levels of ethylene. The aim of this study was to isolate and characterize ACC deaminase-producing bacteria from the rhizosphere of salt-stressed canola （Brassica napus L.）. Out of 105 random bacterial isolates, 15 were able to utilize ACC as the sole source of nitrogen. These 15 isolates were also positive for indole acetic acid （IAA） production. Phylogenetic analysis based on partial 16S rDNA sequences showed that all isolates belonged to fluorescent Pseudomonas spp. In the canola rhizosphere investigated in this study, Pseudomonas fluorescens was the dominant ACC deaminase-producing species. Cluster analysis based on BOX-AIR-based repetitive extragenic palindromic-polymerase chain reaction （BOX-PCR） patterns suggested a high degree of genetic variability in ACC deaminase-producing P. fluorescens strains. The presence of indigenous ACC-degrading bacteria in the rhizosphere of canola grown in saline soils indicates that these bacteria may contribute to salinity tolerance.

lncRNA-PACER upregulates COX-2 and PGE2 through the NF-κB pathway to promote the proliferation and invasion of colorectal-cancer cells

Background p50-associated cyclooxygenase-2 extragenic RNA(PACER)is a recently identified antisense long non-coding RNA(lncRNA)located on the upstream of the promoter region of cyclooxygenase-2(COX-2).Preliminary studies have suggested that PACER is involved in the regulation of COX-2 expression in macrophagocyte and osteosarcoma cells.However,the role of this lncRNA in colorectal cancer(CRC)remains elusive.Here,we investigated the expression of PACER and its effect on cell proliferation and invasion to explore the role of PACER in CRC.Methods Real-time quantitative PCR(RT-qPCR)analysis was used to evaluate the expression of PACER in CRC tissues and cells.Methyl thiazolyl tetrazolium(MTT)analysis was then used to investigate the inhibition effect of PACER knock-down in cell proliferation.The promoting role of this lncRNA on invasion by CRC cells was analysed by wound-healing assays,colony-formation assay,and transwell assays.We then used fluorescence in situ hybridization(FISH)to establish the subcellular localization of PACER.COX-2 protein levels were quantified by Western blot analysis and grayscale scanning analysis following the knock-down of PACER.Luciferase assay was carried out to monitor the modulation of the COX-2 promoter region by PACER.Tumor xenografts models were used to investigate the impact of PACER on the tumorigenesis of CRC cells in vivo.Enzyme-linked immunosorbent assay(ELISA)was then used to quantify prostaglandin E2(PGE2)production upon knock-down of PACER.Results RT-qPCR analysis revealed that PACER was highly expressed in CRC tissues and cells,and a high PACER-expression level was associated with poor prognosis.MTT assay,wound-healing assay,colony-formation assay,and transwell assay revealed that PACER enhanced CRC-cell proliferation,invasion,and metastasis in vitro.Analysis of lncRNA localization by FISH showed that it mainly resided in the nucleus.RT-qPCR showed that PACER increased mRNA levels of COX-2.Western blot analysis demonstrated,under normal circumstances,that knock-down of PACER decreased the COX-2 protein level.In the case of p50 absence,COX-2 protein increased rapidly and remained highly expressed after knocking down PACER.Luciferase assay revealed that PACER modulated the COX-2 promoter region.Mouse xenograft models of CRC revealed that PACER promoted colorectal tumorigenesis in vivo.ELISA revealed that PACER knock-down inhibited PGE2 production.Conclusions PACER modulates COX-2 expression through the nuclear factor kappa B(NF-jB)pathway in CRC.An increased level of PACER enhances proliferation,migration,and invasion of tumor cells by increasing COX-2 and PGE2 synthesis.