Staphylococcus aureus(SA) infections remain a major cause of morbidity and mortality despite the availability of numerous effective anti-staphylococcal antibiotics.This organism is responsible for both nosocomial and ...Staphylococcus aureus(SA) infections remain a major cause of morbidity and mortality despite the availability of numerous effective anti-staphylococcal antibiotics.This organism is responsible for both nosocomial and community-acquired infections ranging from relatively minor skin and soft tissue infections to life-threateningsystemic infections.The increasing incidence of methicillin-resistant strains has granted an increasing use of vancomycin causing a covert progressive increase of its minimum inhibitory concentration(MIC)(dubbed the MIC "creep").In this way,the emergence of vancomycinintermediate SA(VISA) strains and heteroresistantVISA has raised concern for the scarcity of alternative treatment options.Equally alarming,though fortunately less frequent,is the emergence of vancomycin-resistant SA.These strains show different mechanisms of resistance but have similar problems in terms of therapeutic approach.Ultimately,various debate issues have arisen regarding the emergence of SA strains with a minimum inhibitory concentration sitting on the superior limit of the sensitivity range(i.e.,MIC = 2 μg/mL).These strains have shown certain resilience to vancomycin and a different clinical behaviour regardless of vancomycin use,both in methicillin-resistant SA and in methicillin-sensitive SA.The aim of this text is to revise the clinical impact and consequences of the emergence of reduced vancomycin susceptibility SA strains,and the different optimal treatment options known.展开更多
AIM： To investigate the increasing the susceptibility pylon） to metronidazole. mechanisms of aspirin of Helicobacter pylori （H METHODS： Hpylori reference strain 26695 and two metronidazole-resistant isolates of H ...AIM： To investigate the increasing the susceptibility pylon） to metronidazole. mechanisms of aspirin of Helicobacter pylori （H METHODS： Hpylori reference strain 26695 and two metronidazole-resistant isolates of H pylori were included in this study. Strains were incubated in Brucella broth with or without aspirin （1 mmol/L）. The rdxA gene of Hpylori was amplified by PCR and sequenced. The permeability of Hpylori to antimicrobials was determined by analyzing the endocellular radioactivity of the cells after incubated with [7-^3H]-tetracycline. The outer membrane proteins （OMPs） of Hpylori 26695 were depurated and analyzed by SDS-PAGE. The expression of 5 porins （hopA, hopB, hopC, hopD and hopE） and the putative RND efflux system （hefABC） of H pylori were analyzed using real-time quantitative PCR. RESULTS： The mutations in rdxA gene did not change in metronidazole resistant isolates treated with aspirin. The radioactivity of H pylori increased when treated with aspirin, indicating that aspirin improved the permeability of the outer membrane of H pylori. However, the expression of two OMP bands between 55 kDa and 72 kDa altered in the presence of aspirin.The expression of the mRNA of hopA, hopB, hopC, hopD, hopE and herA, hefB, hefC of H pylori did not change when treated with aspirin. CONCLUSION： Although aspirin increases the susceptibility of H pylori to metronidazole, it has no effect on the mutations of rdxA gene of Hpylori. Aspirin increases endocellular concentrations of antimicrobials probably by altering the OMP expression.展开更多
文摘Staphylococcus aureus(SA) infections remain a major cause of morbidity and mortality despite the availability of numerous effective anti-staphylococcal antibiotics.This organism is responsible for both nosocomial and community-acquired infections ranging from relatively minor skin and soft tissue infections to life-threateningsystemic infections.The increasing incidence of methicillin-resistant strains has granted an increasing use of vancomycin causing a covert progressive increase of its minimum inhibitory concentration(MIC)(dubbed the MIC "creep").In this way,the emergence of vancomycinintermediate SA(VISA) strains and heteroresistantVISA has raised concern for the scarcity of alternative treatment options.Equally alarming,though fortunately less frequent,is the emergence of vancomycin-resistant SA.These strains show different mechanisms of resistance but have similar problems in terms of therapeutic approach.Ultimately,various debate issues have arisen regarding the emergence of SA strains with a minimum inhibitory concentration sitting on the superior limit of the sensitivity range(i.e.,MIC = 2 μg/mL).These strains have shown certain resilience to vancomycin and a different clinical behaviour regardless of vancomycin use,both in methicillin-resistant SA and in methicillin-sensitive SA.The aim of this text is to revise the clinical impact and consequences of the emergence of reduced vancomycin susceptibility SA strains,and the different optimal treatment options known.
基金Supported by The National Natural Science Foundation of China, No. 30470777
文摘AIM： To investigate the increasing the susceptibility pylon） to metronidazole. mechanisms of aspirin of Helicobacter pylori （H METHODS： Hpylori reference strain 26695 and two metronidazole-resistant isolates of H pylori were included in this study. Strains were incubated in Brucella broth with or without aspirin （1 mmol/L）. The rdxA gene of Hpylori was amplified by PCR and sequenced. The permeability of Hpylori to antimicrobials was determined by analyzing the endocellular radioactivity of the cells after incubated with [7-^3H]-tetracycline. The outer membrane proteins （OMPs） of Hpylori 26695 were depurated and analyzed by SDS-PAGE. The expression of 5 porins （hopA, hopB, hopC, hopD and hopE） and the putative RND efflux system （hefABC） of H pylori were analyzed using real-time quantitative PCR. RESULTS： The mutations in rdxA gene did not change in metronidazole resistant isolates treated with aspirin. The radioactivity of H pylori increased when treated with aspirin, indicating that aspirin improved the permeability of the outer membrane of H pylori. However, the expression of two OMP bands between 55 kDa and 72 kDa altered in the presence of aspirin.The expression of the mRNA of hopA, hopB, hopC, hopD, hopE and herA, hefB, hefC of H pylori did not change when treated with aspirin. CONCLUSION： Although aspirin increases the susceptibility of H pylori to metronidazole, it has no effect on the mutations of rdxA gene of Hpylori. Aspirin increases endocellular concentrations of antimicrobials probably by altering the OMP expression.
