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Objective To analyze the effects of Litsea cubeba oil on gene expression profile of Candida albicans by comparing the differential gene expression profile after exposure to Litsea cubeba oil using genome-wide gene expression array.Methods Candida albicans ATCC90028 was exposed to Litsea cubeba oil for 90 min.Then RNA was isolated and gene expression profiles were compared to identify the differential gene expression profile using cDNA microarray analysis.Results A total of 491 geneswerefoundtoberesponsivetoLitseacubebaoil,accountingforabout11% ofthetotalnumberofgenesinCandida albicans (491/4 634),of which 216 genes were up-regulated and 275 down-regulated.These differentially expressed genes included genes encoding the key target enzyme in ergosterol biosynthesis pathway,genes in stress response,DNA replication and repair,molecular transport,and energy metabolism.Conclusions Litsea cubeba oil has significant effect on the expression of about 1 1% genes of Candida albicans genome.We presume that the genes encoding the key target enzyme in ergosterol biosynthesis pathway may contribute to the action of Litseacubeba oil on Candidaalbicans,which is similar to azole antifungal drugs.However,the role of other differentially expressed genes in the action of Litseacubeba oil on Candidaalbicans remains unclear,which deserves further study to characterize their potential association with the antifungal effect of Litsea cubeba oil.
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OBJECTIVE To investigate the relationship between phenotypes and genotypes of clinical isolates of ESBLs-producing Klebsiella pneumoniae.METHODS Agar dilution method was used to test the MICs of 11 antibiotics against 67 ESBLs-producing K.pneumoniae strains.PCR was performed for amplifying ?-lactamase-encoding genes of SHV-,TEM-,and CTX-M-type,and the PCR products of some strains were cloned and sequenced to identify their gene serotypes.RESULTS With no imipenem-resistant strains among 67 strains,their resistant rates to 10 kinds of antibiotics were 10.45-89.55% The cross-resistant rates to aminoglycosides of 60 strains and to ?-lactams of 44 strains were 88.33% and 40.91%,respectively.The positive rates of SHV-,TEM-,and CTX-M-type for 67 strains were 91.04%,56.72% and 28.36%,respectively,and SHV-12,TEM-1 and CTX-M-3 genotypes were found in 7 strains by cloning and sequencing.CONCLUSIONS Sixty seven strains of ESBLs-producing K.pneumoniae present a clear feature of multi-resistance and cross-resistance to most of antibiotics except imipenem,among them there are 7 strains producing SHV-12 and CTX-M-3 extended-spectrum ?-lactamase coexistent with TEM-1 broad-spectrum ?-lactamase.
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Objective To analyse the encoding gene of ? lactamase of the clinically isolated Klebsiela pneumoniae 99 799 and to identify its subtype. Methods The gene of ? lactamase derived from a stain of Klebsiela pneumoniae 99 799 named as was amplified by PCR. The purified PCR product was cloned into pUCm T vector and sequenced by Sanger's dideoxy chain termination composition method. Results The encoded gene of the bacterium was identified as TEM by PCR. It had the same sequence as the gene encoding TEM 1 and positioned at the 150 bp and 80 bp plasmids. Conclusion The TEM 1 ? lactamase exists in Chongqing area.
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Objective To investigate the alterations of outer membrane permeation of multiple-antibiotic-resistant Proteus mirabilis.Methods Laboratory-derived cefotaxime-resistant mutants were induced by serial passages of clinical isolated susceptible Proteus mirabilis on cefotaxime-containing agar.Thereafter,the outer membrane proteins(OMP)of the parental strains and mutants were analyzed by sodium dodeeyl sulfate-polyacrylamide gradient gel electrophresis(SDS-PAGE)and the uptake of ciprofloxacin (CPLX)was determined with high pressure liquid chromatography(HPLC).Lastly,morphological analysis was performed by scanning and transmission electron microscopy.Results Compared with the parental strains.the mutants wete resistant to quinolones,cephalosporins and penicillins;the content of OMP with relative molecular weight 40 000 was reduced and that of 37 000 0MP was increased.The uptake of CPLX was reduced and the ratios of peak concentration were decreased to 1:1.74,1:1.53 compared with that of suseeptible strains.CPLX concentration absorbed was lower than the break point 1 mg/L of resistance and the difference of CPLX intracellular concentration between resistant and susceptible strains was less than 2 times.which resulted in much more increase of minimum inhibitory concentrations(MICs).Meanwhile,it was observed under electronic microscopy that resistant strains lost the rodlike shape and had more distinctive membrane fold,wider periplasmic space and les8 nucleiods.Conclusion The multiple-antibiotic-resistant Proteus mirabilis shows decrease of drug uptake and changes of ultrastructure,which may be related to alterations of outer membrane permeation.
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The effects of antibacterials are mainly focus on inhibiting the proliferation of the bacteriums or killing them directly in various ways. Consequently, antibacterials were mainly used in the therapy of infectious diseases. However, besides the effect of anti bacterials, some antibacterials have other effects as well, such as the effects of antitumor, immunomodulation and antivirus etc. So it is very important to understand the effects and their mechanisms of antibacterials roundly so as to apply them more rationally.