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1.
Six methicillin-resistant Staphylococcus aureus MRSA strains from two nosocomial infection cases described in a previous study [15], of which two occurred in March and the other four in May, 2005, were found to possess one copy of class 1 integron with aadA2 gene cassette located on chromosomes by Southern hybridization. Polymerase chain reaction (PCR) detection of mecA and pvl, SCCmec typing, multilocus sequence typing (MLST), spaA typing and coa typing were also performed. The results revealed 6 MRSA fell into the ST239-MRSA-III group (clonal complex 8), with the spaA type GKAOMQ and coa type HIJKL, whereas the pvl locus was not detected. DNA fingerprinting analysis by random amplified polymorphic DNA-PCR using three different assays were also performed, and all strains exhibited identical patterns, indicating that they were clonally related and might be mainly due to a specific clone in the hospital. This was the first time, to our knowledge, that class 1 integron-bearing MRSA (I-MRSA), simultaneously carrying two mobile genetic elements was confirmed: class 1 integron and SCCmec. 相似文献
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Young-Joon Lee Hye-Jeong Jang In-Young Chung You-Hee Cho 《Journal of microbiology (Seoul, Korea)》2018,56(8):534-541
Non-mammalian infection models have been developed over the last two decades, which is a historic milestone to understand the molecular basis of bacterial pathogenesis. They also provide small-scale research platforms for identification of virulence factors, screening for antibacterial hits, and evaluation of antibacterial efficacy. The fruit fly, Drosophila melanogaster is one of the model hosts for a variety of bacterial pathogens, in that the innate immunity pathways and tissue physiology are highly similar to those in mammals. We here present a relatively simple protocol to assess the key aspects of the polymicrobial interaction in vivo between the human opportunistic pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, which is based on the systemic infection by needle pricking at the dorsal thorax of the flies. After infection, fly survival and bacteremia over time for both P. aeruginosa and S. aureus within the infected flies can be monitored as a measure of polymicrobial virulence potential. The infection takes ~24 h including bacterial cultivation. Fly survival and bacteremia are assessed using the infected flies that are monitored up to ~60 h post-infection. These methods can be used to identify presumable as well as unexpected phenotypes during polymicrobial interaction between P. aeruginosa and S. aureus mutants, regarding bacterial pathogenesis and host immunity. 相似文献
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Jing-Ze Zhang Fu-Qiang Chu De-Ping Guo Kevin D. Hyde Guang-Lin Xie 《Mycological Progress》2012,11(2):499-508
Ustilago esculenta is a biotrophic smut fungus that parasitizes Zizania latifolia, an edible aquatic vegetable of the southern China region. Infection results in swelling of the upper parts of the Z. latifolia culm which are called jiaobai and have a unique flavor and delicacy and are popular among Chinese. The infection process of Z. latifolia by U. esculenta was investigated with light and electron microscopy. Distribution of hyphae was uneven in plants; hyphae were mainly present
in the swollen upper parts (jiaobai), the nodal regions of mature culms and old rhizomes and buds or shoots. Hyphae were rare in the internodes of mature culms
and were fewer in the internodes of old rhizomes. All new buds produced on the nodes of culms and rhizomes were infected by
hyphae in November before and in March after overwintering. The hyphae grew into the buds from the parent nodes via intervascular
tissues only or via parenchyma tissues and vascular bundles. Hyphae extended within and between the host cells and frequently
formed hyphal aggregations or clusters, not only in the mature tissues but also in developing tissues. The typical interface
between the fungal hyphal wall and invaginated host plasma membrane comprised a sheath. The sheath surrounding a hyphae comprised
an outer electron-opaque matrix and an inner electron-dense layer. The electron-opaque matrix layers were thicker in jiaobai tissues, ranging from 0.28 to 0.85 μm. The electron-dense hyphal coatings were more conspicuous in the young buds or shoots
and mature culms than in the jiaobai. The intercellular hyphae caused large cavity formation between the cells or rupture of host cell walls, for gaining entry
into host cells. The broken host cell wall fused with the electron-opaque matrix of the hyphal sheath as an interactive interface.
The teliospore wall and wall ornamentation development was the same in postmature jiaobai tissues with sporadic sori and in the huijiao (jiaobai tissues containing the massive sori), but a sheath enveloping the teliospore was more transparent in the process of teliospore
development in the jiaobai than in the huijiao. 相似文献
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Staphylococcus aureus is a multidrug-resistant pathogen that not only causes a diverse array of human diseases, but also is able to survive in
potentially dry and stressful environments, such as the human nose, on skin and on inanimate surfaces such as clothing and
surfaces. This study investigated parameters governing desiccation tolerance of S. aureus and identified several components involved in the process. Initially, the role of environmental parameters such as temperature,
growth phase, cell density, desiccation time and protectants in desiccation tolerance were determined. This established a
robust model of desiccation tolerance in which S. aureus has the ability to survive on dry plastic surfaces for more than 1,097 days. Using a combination of a random screen and defined
mutants, clpX, sigB and yjbH were identified as being required for desiccation tolerance. ClpX is a part of the ATP-dependent ClpXP protease, important for protein turnover, and YjbH has a proposed linked function.
SigB is an accessory sigma factor with a role in generalized stress resistance. Understanding the molecular mechanisms that
govern desiccation tolerance may determine the break points to be exploited to prevent the spread of this dangerous pathogen
in hospitals and communities. 相似文献
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Aminoglycoside resistance in six clinically isolated Staphylococcus aureus was evaluated. Genotypical examination revealed that three isolates (HLGR-10, HLGR-12, and MSSA-21) have aminoglycoside-modifying
enzyme (AME) coding genes and another three (GRSA-2, GRSA-4, and GRSA-6) lacked these genes in their genome. Whereas isolates
HLGR-10 and HLGR-14 possessed bifunctional AME coding gene aac(6′)-aph(2′′), and aph(3′)-III and showed high-level resistance to gentamycin and streptomycin, MSSA-21 possessed aph(3′)-III and exhibited low resistance to gentamycin, streptomycin, and kanamycin. The remaining three isolates (GRSA-2, GRSA-4, and
GRSA-6) exhibited low resistance to all the aminoglycosides because they lack aminoglycoside-modifying enzyme coding genes
in their genome. The transmission electron microscopy of the three isolates revealed changes in cell size, shape, and septa
formation, supporting the view that the phenomenon of adaptive resistance is operative in these isolates. 相似文献
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Le Quoc Hung Takashi Asaeda Takeshi Fujino Bakari J. Mnaya 《Wetlands Ecology and Management》2007,15(2):105-111
The influence of Phragmites australis on the growth of Zizania latifolia, and the morphological characteristics of both species, were investigated at two nutrient levels. The experiment was carried
out over three growing seasons between May 2003 and December 2005. The experimental plot was longitudinally divided into two
equal halves, one of which was planted with Zizania latifolia (Zizania zone) and the other one with Phragmites australis (Phragmites zone). Four weeks after transplantation, the plot was again divided horizontally, perpendicular to the previous
division, and subject to low (LN) and high nutrient (HN) treatments. Measured growth indices of the two species were more
developed in the HN than in the LN treatments. Both species were observed to invade each other’s zone, but Phragmites latifolia seemed to out-compete Zizania latifolia individuals. This was evident from the decrease in below ground biomass of Zizania latifolia in the third growing season and deterioration in above ground organs with time. It was concluded that Phragmites australis out-competes Zizania latifolia due to better developed root and rhizome system. 相似文献
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O. D. Hendrickson N. I. Smirnova A. V. Zherdev V. K. Gasparyan B. B. Dzantiev 《Applied Biochemistry and Microbiology》2017,53(1):107-113
In this study, we developed a microplate sandwich analysis of Escherichia coli and Staphylococcus aureus bacterial pathogens based on the interaction of their cell wall carbohydrates with natural receptors called lectins. An immobilized lectin-cell-biotinylated lectin complex was formed in this assay. Here, we studied the binding specificity of several plant lectins to E. coli and S. aureus cells, and pairs characterized by high-affinity interactions were selected for the assay. Wheat germ agglutinin and Ricinus communis agglutinin were used to develop enzyme-linked lectinosorbent assays for E. coli and S. aureus cells with the detection limits of 4 × 106 and 5 × 105 cells/mL, respectively. Comparison of the enzyme-linked immonosorbent assay and the enzyme-linked lectinosorbent assay demonstrated no significant differences in detection limit values for E. coli. Due to the accessibility and universality of lectin reagents, the proposed approach is a promising tool for the control of a wide range of bacterial pathogens. 相似文献
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Xuping Yu Li Zheng Junshu Yang Ting Lei Yinduo Ji 《World journal of microbiology & biotechnology》2011,27(4):897-905
In this study, we characterized the essentiality of enolase for growth of Staphylococcus aureus in vitro by using a TetR-regulated antisense RNA expression technology. The induced enolase antisense RNA dramatically decreased
the production of enolase, which in turn inhibited the growth of S. aureus. In addition, we found that the down-regulation of eno expression can effectively inhibit Triton X-100-induced lysis and alleviate penicillin-caused cell lysis. To further confirm
the specific effect of enolase on autolysis, we constructed an enolase over-expression system and demonstrated that the over-expression
of enolase enhances both Triton X-100 and penicillin-induced cell lysis without increasing cell growth rate. We also performed
hydrolase induced autolysis and zymographic assays and found that enolase had no impact on either bacterial sensitivity to
hydrolase or hydrolase activity. Moreover, we found that the down-regulating expression of enolase selectively increased bacterial
sensitivity to phosphomycin. Taken together, the above results suggest that the enolase is essential for S. aureus and involved in the process of bacterial autolysis. 相似文献
13.
Fiona M Burke Niamh McCormack Simonetta Rindi Pietro Speziale Timothy J Foster 《BMC microbiology》2010,10(1):160
Background
Fibronectin binding proteins A and B (FnBPA and FnBPB) mediate adhesion of S. aureus to fibrinogen, elastin and fibronectin. We previously identified seven different isotypes of FnBPA based on divergence in the fibrinogen- and elastin-binding A domains. The variation created differences in antigenicity while ligand binding functions were retained. Here, FnBPB variation was examined in both human and bovine isolates and compared to that of FnBPA. 相似文献14.
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Hwa Yun Cha Hyun Ok Kim Jong Sook Jin Je Chul Lee 《Journal of microbiology (Seoul, Korea)》2010,48(4):533-535
The genetic and epidemiological features of four vancomycin-intermediate Staphylococcus aureus (VISA) isolates obtained from a Korean hospital were evaluated in this study. The VISA isolates were genotyped as sequence
type (ST) 5-staphylococcal cassette chromosome mec (SCCmec) II variant (n=2) and ST239-SCCmec III (n=2), which were derived from the predominant methicillin-resistant S. aureus (MRSA) clones in Korean hospitals. One VISA isolate was acquired during vancomycin treatment, whereas three VISA isolates
were obtained from the patients who had not previously been exposed to glycopeptides. As VISA is likely to arise from the
predominant MRSA clones and may then possibly spread between patients, the emergence of VISA should be monitored with great
care in hospitals. 相似文献
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Ningning Wang Hongyan Wang Hui Wang Di Zhang Ying Wu Xiufang Ou Shuang Liu Zhenying Dong Bao Liu 《BMC plant biology》2010,10(1):190
Background
It is widely recognized that interspecific hybridization may induce "genome shock", and lead to genetic and epigenetic instabilities in the resultant hybrids and/or backcrossed introgressants. A prominent component involved in the genome shock is reactivation of cryptic transposable elements (TEs) in the hybrid genome, which is often associated with alteration in the elements' epigenetic modifications like cytosine DNA methylation. We have previously reported that introgressants derived from hybridization between Oryza sativa (rice) and Zizania latifolia manifested substantial methylation re-patterning and rampant mobilization of two TEs, a copia retrotransposon Tos17 and a MITE mPing. It was not known however whether other types of TEs had also been transpositionally reactivated in these introgressants, their relevance to alteration in cytosine methylation, and their impact on expression of adjacent cellular genes. 相似文献17.
Elisabeth Hodille Cédric Badiou Caroline Bouveyron Michèle Bes Anne Tristan François Vandenesch Gérard Lina Oana Dumitrescu 《Annals of clinical microbiology and antimicrobials》2018,17(1):38
Clindamycin is a protein synthesis inhibitory agent that has the ability to suppress the expression of virulence factors in Staphylococcus aureus. Recent guidelines recommend the use of clindamycin for the treatment of toxin-mediated infections. Clindamycin modulates virulence expression at sub-inhibitory concentrations (sub-MICs) in clindamycin-susceptible S. aureus strains but previous report shown that this effect was supressed for constitutive clindamycin resistant strains. However, no data are currently available on the impact of clindamycin at sub-MICs on the virulence of inducible clindamycin-resistant S. aureus strains. Here, we show that sub-MICs of clindamycin decrease Panton–Valentine leucocidin, toxic-shock-staphylococcal toxin (TSST-1) and alpha-haemolysin (Hla) expression in six inducible clindamycin-resistant isolates cultivated in vitro in CCY medium. These results suggest that the clindamycin anti-toxin effect is retained for inducible clindamycin-resistant S. aureus isolates; therefore, its usage should be considered within the treatment regimen of toxin related infections for inducible clindamycin-resistant S. aureus. 相似文献
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A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
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Wen-Ru Li Xiao-Bao Xie Qing-Shan Shi Shun-Shan Duan You-Sheng Ouyang Yi-Ben Chen 《Biometals》2011,24(1):135-141
The antibacterial activity and mechanism of silver nanoparticles (Ag-NPs) on Staphylococcus aureus ATCC 6538P were investigated in this study. The experiment results showed the minimum bactericidal concentration (MBC) of
Ag-NPs to S. aureus was 20 μg/ml. Moreover, when bacteria cells were exposed to 50 μg/ml Ag-NPs for 6 h, the cell DNA was condensed to a tension
state and could have lost their replicating abilities. When S. aureus cells were exposed to 50 μg/ml Ag-NPs for 12 h, the cell wall was breakdown, resulting in the release of the cellular contents
into the surrounding environments, and finally became collapsed. And Ag-NPs could reduce the enzymatic activity of respiratory
chain dehydrogenase. Furthermore, the proteomic analysis showed that the expression abundance of some proteins was changed
in the treated bacterial cell with Ag-NPs, formate acetyltransferase increased 5.3-fold in expression abundance, aerobic glycerol-3-phosphate
dehydrogenase decreased 6.5-fold, ABC transporter ATP-binding protein decreased 6.2-fold, and recombinase A protein decreased
4.9-fold. 相似文献