Distribution and drug resistance of pathogenic bacteria isolated from cancer hospital in 2013

Objective： To understand distribution and drug resistance of pathogenic bacteria from a specialized cancer hospital in 2013 in order to provide a basis for rational clinical antimicrobial agents. Methods： Pathogenic bacteria identification and drug sensitivity tests were performed with a VITEK 2 compact automatic identification system and data were analyzed using WHONET5.6 software.Results： Of the 1,378 strains tested, 980 were Gram-negative bacilli, accounting for 71.1%, in which Klebsiella pneumonia, Escherichia coli and Pseudomonas aeruginosa were the dominant strains. We found 328 Gram-positive coccus, accounting for 23.8%, in which the amount of Staphylococcus aureus was the highest. We identified 46 fungi, accounting for 4.1%. According to the departmental distribution within the hospital, the surgical departments isolated the major strains, accounting for 49.7%. According to disease types, lung cancer, intestinal cancer and esophagus cancer were the top three, accounting for 20.9%, 17.3% and 14.2%, respectively. No strains were resistant to imipenem, ertapenem or vancomycin.Conclusions： Pathogenic bacteria isolated from the specialized cancer hospital have different resistance rates compared to commonly used antimicrobial agents; therefore antimicrobial agents to reduce the morbidity and mortality of infections should be used.

Dietary intake of bamboo vinegar and charcoal powder(BVC)enhances resistance of African catfi sh Clarias gariepinus to bacterial pathogen

Although the immunomodulatory activity of bamboo vinegar and charcoal powder(BVC)has been increasingly documented in domestic animals,the use of BVC as immunostimulant in fi sh aquaculture awaits verifi cation.In the present study,the immunostimulatory impacts of dietary BVC intake were investigated in an important aquaculture fi sh species,the African catfi sh Clarias gariepinus.Results show that the pathogen resistance of African catfi sh was signifi cantly improved by dietary BVC intake at the tested levels(0.5%-2%),as indicated by higher survival rates(approximately 1.52-1.85 times that without BVC supplementation)upon intraperitoneally injection of bacterial pathogen Aeromonas hydrophila.In addition,both the count and phagocytic activity of blood cells were signifi cantly up-regulated by a 45-day dietary supplementation of BVC.Moreover,compared to that of the control,fi sh individuals fed BVC containing diets exhibited signifi cant higher activities of superoxide dismutase(SOD),myeloperoxidase(MPO),and lysozyme(LYZ).The content of immunoglobulin M(IgM)in serum of African catfi sh was also induced by dietary BVC supplementation.Furthermore,the expression levels of interleukin-8(IL-8),toll-like receptor 1 and 5(TLR1 and TLR5),myeloid diff erentiation factor 88(MyD88),and nuclear factor kappa B(NFκB)in the head kidney were signifi cantly up-regulated.Our fi ndings indicate BVC could be an eff ective immunostimulant in teleost species,which may enhance fi sh immunity through improving hematic parameters,activating bioactive humoral molecules,and up-regulating immune related molecular pathways.

Response and resistance of cereal crops to pathogens

The special topic of the two papers is the systemic acquired resistance （SAR） and pathogenesis-related protein genes （PR）. SAR is an enhanced resistance against further potential parasite beyond the initial infection site, which can be induced by either pathogen infection or exogenous inducer, including synthetic chemicals and natural prod- ucts. As a ＂whole-plant＂ resistance defense, SAR confers broad-spectrum immunity to widely diverse pathogenic microorganisms, such as viruses, bacteria and fungi for a relatively long lasting period. Convincingly, it is a promising way to prevent crop diseases by activating the plants＇ own natural defenses via application of chemical inducers or creating resistant wheat cultivars.

Halomonas-PHB protects gnotobiotic Artemia against Vibrio and m odifies Artemia gut microbiota in xenic culture conditions

The prokaryotic cell storage compound ploy-β-hydroxybutyrate(PHB)has been considered as prebiotics that can be applied in aquaculture.In this paper,the dietary effect of a PHB-accumulating Halomonas strain(HM·PHB)identified from our previous work were studied in Artemia under gnotobiotic and xenic culture conditions,in comparison of Halomonas without PHB accumulation(HM)and microalgae Isochrysis(ISO)feeding.Under gnotobiotic condition,both HM·PHB and HM served as sole food supporting Artemia survival.Although both HM·PHB and HM feeding had no significant difference on Artemia survival percentage(P>0.05),HM·PHB significantly improved their resistance against Vibrio anguillarum challenge(P<0.05).Mass Artemia culture were further performed in xenic condition.Compared to ISO,HM·PHB feeding protected Artemia against V.anguillarum challenge(P<0.05),and HM·PHB and HM feeding resulted in increased T-AOC,pepsin,T-SOD and CAT activities(P<0.05).High throughput sequencing analysis showed that HM·PHB and HM feeding resulted in a lower Artemia gut microbial diversity(P<0.05),and modified the gut microbial community by remarkably reducing the Vibrio proportion.The outcome of the paper confirmed the beneficial effect of Halomonas-PHB in Artemia culture,which supports the use of Halomonas-PHB in the production of bio-secured live feed Artemia.

Biocontrol agents modulate phyllosphere microbiota interactions against pathogen Pseudomonas syringae

The pathogen Pseudomonas syringae,responsible for a variety of diseases,poses a considerable threat to global crop yields.Emerging biocontrol strategies employ antagonistic microorganisms,utilizing phyllosphere microecology and systemic resistance to combat this disease.However,the interactions between phyllosphere microbial dynamics and the activation of the plant defense system remain poorly understood.Here we show significant alterations in phyllosphere microbiota structure and plant gene expression following the application of biocontrol agents.We reveal enhanced collaboration and integration of Sphingomonas and Methylobacterium within the microbial co-occurrence network.Notably,Sphingomonas inhibits P.syringae by disrupting pathogen chemotaxis and virulence.Additionally,both Sphingomonas and Methylobacterium activate plant defenses by upregulating pathogenesis-related gene expression through abscisic acid,ethylene,jasmonate acid,and salicylic acid signaling pathways.Our results highlighted that biocontrol agents promote plant health,from reconstructing beneficial microbial consortia to enhancing plant immunity.The findings enrich our comprehension of the synergistic interplays between phyllosphere microbiota and plant immunity,offering potential enhancements in biocontrol efficacy for crop protection.

Antimicrobial usage and resistance in beef production

Antimicrobials are critical to contemporary high-intensity beef production. Many different antimicrobials are approved for beef cattle, and are used judiciously for animal welfare, and controversially, to promote growth and feed efficiency. Antimicrobial administration provides a powerful selective pressure that acts on the microbial community, selecting for resistance gene determinants and antimicrobial-resistant bacteria resident in the bovine flora. The bovine microbiota includes many harmless bacteria, but also opportunistic pathogens that may acquire and propagate resistance genes within the microbial community via horizontal gene transfer. Antimicrobial-resistant bovine pathogens can also complicate the prevention and treatment of infectious diseases in beef feedlots,threatening the efficiency of the beef production system. Likewise, the transmission of antimicrobial resistance genes to bovine-associated human pathogens is a potential public health concern. This review outlines current antimicrobial use practices pertaining to beef production, and explores the frequency of antimicrobial resistance in major bovine pathogens. The effect of antimicrobials on the composition of the bovine microbiota is examined, as are the effects on the beef production resistome. Antimicrobial resistance is further explored within the context of the wider beef production continuum, with emphasis on antimicrobial resistance genes in the food chain, and risk to the human population.

The Genetic and Molecular Basis of Plant Resistance to Pathogens

Plant pathogens have evolved numerous strategies to obtain nutritive materials from their host, and plants in turn have evolved the preformed physical and chemical barriers as well as sophisticated two-tiered immune system to combat pathogen attacks. Genetically, plant resistance to pathogens can be divided into qualitative and quantitative disease resistance, conditioned by major gene（s） and multiple genes with minor effects, respectively. Qualitative disease resistance has been mostly detected in plant defense against biotrophic pathogens, whereas quantitative disease resistance is involved in defense response to all plant pathogens, from biotrophs, hemibiotrophs to necrotrophs. Plant resistance is achieved through interception of pathogen-derived effectors and elicitation of defense response. In recent years, great progress has been made related to the molecular basis underlying host--pathogen interactions. In this review, we would like to provide an update on genetic and molecular aspects of plant resistance to pathogens.

Root exudates mediate plant defense against foliar pathogens by recruiting beneficial microbes

Plants are capable of releasing specific root exudates to recruit beneficial rhizosphere microbes upon foliar pathogen invasion attack,including long-chain fatty acids,amino acids,short-chain organic acids and sugars.Although long-chain fatty acids and amino acids application have been linked to soil legacy effects that improve future plant performance in the presence of the pathogen,the precise mechanisms involved are to a large extent still unknown.Here,we conditioned soils with long-chain fatty acids and amino acids application(L+A)or short-chain organic acids and sugars(S+S)to examine the direct role of such exudates on soil microbiome structure and function.The L+A treatment recruited higher abundances of Proteobacteria which were further identified as members of the genera Sphingomonas,Pseudomonas,Roseiflexus,and Flavitalea.We then isolated the enriched bacterial strains from these groups,identifying ten Pseudomonas strains that were able to help host plant to resist foliar pathogen infection.Further investigation showed that the L+A treatment resulted in growth promotion of these Pseudomonas strains.Collectively,our data suggest that long-chain fatty acids and amino acids stimulated by foliar pathogen infection can recruit specific Pseudomonas populations that can help protect the host plant or future plant generations.

Transcriptome Comparison of Susceptible and Resistant Wheat in Response to Powdery Mildew Infection

Powdery mildew （Pro） caused by the infection of Blumeria graminis f. sp. tritici （Bgt） is a worldwide crop disease resulting in significant loss of wheat yield. To profile the genes and pathways responding to the Bgt infection, here, using Affymetrix wheat microarrays, we compared the leaf transcriptomes before and after Bgt inoculation in two wheat genotypes, a Pm-susceptible cultivar Jingdong 8 （S） and its near-isogenic line （R） carrying a single Pm resistant gene Pm30. Our analysis showed that the original gene expression status in the S and R genotypes of wheat was almost identical before Bgt inoculation, since only 60 genes exhibited differential expression by P = 0.01 cutoff. However, 12 h after Bgt inoculation, 3014 and 2800 genes in the S and R genotype, respectively, responded to infec- tion. A wide range of pathways were involved, including cell wall fortification, flavonoid biosynthesis and metabolic processes. Further- more, for the first time, we show that sense-antisense pair genes might be participants in wheat-powdery mildew interaction. In addition, the results of qRT-PCR analysis on several candidate genes were consistent with the microarray data in their expression patterns. In summary, this study reveals leaf transcriptome changes before and after powdery mildew infection in wheat near-isogenic lines, suggest- ing that powdery mildew resistance is a highly complex systematic response involving a large amount of gene regulation.

Clinical study of distribution and drug resistance of pathogens in patients with severe acute pancreatitis

Background Previous researches about necrotic pancreatic tissue infections are numerous, but the study on systemic infection related to the severe acute pancreatitis （SAP） treatment period is limited. This study aimed to investigate the distribution and drug resistance of pathogenic bacteria in patients who had hepatobiliary surgery for SAP during the past three years. Methods A retrospective study was conducted on the distribution, category and drug resistance of pathogenic bacteria in patients who had hepatobiliary surgery for SAP from 2008 to 2011. Results A total of 594 pathogenic bacteria samples were isolated. Among them 418 isolates （70.4%） were Gram bacteria negative, 142 isolates （23.9%） were Gram bacteria positive, and 34 isolates （5.7%） were found fungi. The most common Gram negative bacteria were Escherichia coli （19.8%）, and the dominant Gram positive pathogenic bacteria were Enterococcus faecium. The distribution of SAP-related infectious pathogens was mainly in peritoneal drainage fluid, sputum, bile, and wound secretions. Almost all the Gram negative pathogenic bacteria were sensitive to carbapenum. Extended-spectrum I]-Iactamases （ESBLs） producing strains were more resistant to penicillins and cephalosprins than the ESBLs non-producing strains. Staphylococcus was sensitive to vancomycin and linezolid. The drug resistance of meticillin-resistant staphylococcus （MRS） to commonly used antibiotics was higher than meticillin-sensitive streptococcus （MSS）. Enterococcus sp. exhibited lower drug-resistance rates to vancomycin and linezolid. Conclusions Gram negative bacteria were the dominant SAP-related infection after hepatobiliary surgery. A high number of fungal infections were reported. Drug resistant rates were high. Rational use of antibiotics according to the site of infection, bacterial species and drug sensitivity, correctly executing the course of treatment and enhancing hand washing will contribute to therapy and prevention of SAP-related infection and decrease its mortality.

沙拉沙星体外诱导鼠伤寒沙门菌耐药实验

目的为获得体外鼠伤寒沙门菌(Salmonella typhimurium)对盐酸沙拉沙星(sarafloxacin hydrochloride)的活性耐药菌株,研究诱导其产生耐药的盐酸沙拉沙星最低浓度,为评价食品中沙拉沙星残留导致的微生物耐药提供依据。方法设置盐酸沙拉沙星0.001、0.002 5、0.005、0.025、0.05、0.1μg/ml实验组和空白对照组、NaOH溶剂对照组,采用NCCLS法测试最小抑菌浓度,对鼠伤寒沙门菌进行耐药诱导,耐药判断为≥8×MIC(0.25μg/ml)。对产生耐药的鼠伤寒沙门菌的gyrA基因片段进行PCR扩增,焦磷酸凝胶测序法鉴定gyrA基因常见5个位点观察突变。结果盐酸沙拉沙星在0.005μg/ml水平传到第10代时,MIC增大32倍,抑菌浓度增加到1μg/ml,耐药菌增殖停止;传到第25代时,鼠伤寒沙门菌gyrA基因Ser83位点发生突变,获得多株稳定、有生物活性的耐药菌株。沙拉沙星浓度≥0.025μg/ml时,细菌不生长;沙拉沙星浓度≤0.002 5μg/ml时细菌生长,不产生耐药。结论沙拉沙星浓度为0.005μg/ml时可体外诱导鼠伤寒沙门菌产生耐药,经传代后获得具生物活性的耐药菌株。

The chromosome-scale genome of Phoebe bournei reveals contrasting fates of terpene synthase (TPS)-a and TPS-b subfamilies

Terpenoids,including aromatic volatile monoterpenoids and sesquiterpenoids,function in defense against pathogens and herbivores.Phoebe trees are remarkable for their scented wood and decay resistance.Unlike other Lauraceae species investigated to date,Phoebe species predominantly accumulate sesquiterpenoids instead of monoterpenoids.Limited genomic data restrict the elucidation of terpenoid variation and functions.Here,we present a chromosome-scale genome assembly of a Lauraceae tree,Phoebe bournei,and identify 72 full-length terpene synthase(TPS)genes.Genome-level comparison shows pervasive lineage-specific duplication and contraction of TPS subfamilies,which have contributed to the extreme terpenoid variation within Lauraceae species.Although the TPS-a and TPS-b subfamilies were both expanded via tandem duplication in P.bournei,more TPS-a copies were retained and constitutively expressed,whereas more TPS-b copies were lost.The TPS-a genes on chromosome 8 functionally diverged to synthesize eight highly accumulated sesquiterpenes in P.bournei.The essential oil of P.bournei and its main component,b-caryophyllene,exhibited antifungal activities against the three most widespread canker pathogens of trees.The TPS-a and TPS-b subfamilies have experienced contrasting fates over the evolution of P.bournei.The abundant sesquiterpenoids produced by TPS-a proteins contribute to the excellent pathogen resistance of P.bournei trees.Overall,this study sheds light on the evolution and adaptation of terpenoids in Lauraceae and provides valuable resources for boosting plant immunity against pathogens in various trees and crops.

Role of the tomato fruit ripening regulator MADS-RIIM in resistance to Botrytis cinerea infection

Tomato MADS-RIN(RIN)transcription factor has been shown to be a master activator regulating fruit ripening.Recent studies have revealed that in addition to activating many other cell wall genes,it also represses expression of XTH5,XTH8,and MAN4a,which are positively related to excess flesh softening and cell wall degradation,which might indicate it has a potential role in pathogen resistance of ripening fruit.In this study,both wild-type(WT)and RIN-knockout(RIN-KO)mutant tomato fruit were infected with Botrytis cinerea to investigate the function of RIN in defense against pathogen infection during ripening.The results showed that RIN-KO fruit were much more sensitive to B.cinerea infection with larger lesion sizes.Transcriptome data and qRT-PCR assay indicate genes of phenylalanine ammonialyase (PAL)and chitinase(CHI)in RIN-KO fruit were reduced and their corresponding enzyme activities were decreased.Transcripts of genes encoding pathogenesis-related proteins(PRs),including PR1a,PRSTH2,and APETALA2/Ethylene Response Factor(AP2/ERF)including ERF.A1,Pti5,Pti6,ERF.A4,were reduced in RIN-KO fruit compared toWT fruit.Moreover,in the absence of RIN the expression of genes encoding cell wallmodifying enzymes XTH5,XTH8,MAN4a has been reported to be elevated,which is potentially correlated with cell wall properties.When present,RIN represses transcription of XTH5 by activating ERF.F4,a class II(repressor class)EffFgene family member,and ERF.F5.These results support the conclusion that RIN enhances ripening-related resistance to gray mold infection by upregulating pathogen-resistance genes and defense enzyme activities as well as reducing accumulation of transcripts encoding some cell wall enzymes.