Objective: To investigate the synergistic effect between rhein(RHE) and oxacillin against Staphylococcus aureus(MRSA) at the gene level. Method: A minimum inhibitory concentration and checkerboard dilution test were c...Objective: To investigate the synergistic effect between rhein(RHE) and oxacillin against Staphylococcus aureus(MRSA) at the gene level. Method: A minimum inhibitory concentration and checkerboard dilution test were conducted to evaluate antibacterial activity. Reverse transcriptase polymerase chain reaction was conducted to investigate the gene expressions. Results: RHE exhibited a minimum inhibitory concentration of 62.5-250.0 μg/mL against various MRSA strains and the reference strain, respectively. As revealed by the checkerboard assay, a combination of RHE and oxacillin exhibited synergistic or partially synergistic effects against MRSA strains. RHE decreased the expressions of mecA/blaZ in a dose-dependent manner. RHE also decreased the expressions of the regulator genes mecI/blaI and mecR1/blaR1. Conclusions: We suggest that RHE affects the activity of mecR1/blaR1, which is located in the cell membrane of MRSA and results in the suppression of mecA/mecI/mecR1 and blaZ/blaI/blaR1 gene expressions.展开更多
AIM: To study the presence of various nucleic acids targets of Staphylococcus aureus(S. aureus) during bacterial growth and antibiotic induced killing in relation to viability.METHODS: S. aureus was cultured to log ph...AIM: To study the presence of various nucleic acids targets of Staphylococcus aureus(S. aureus) during bacterial growth and antibiotic induced killing in relation to viability.METHODS: S. aureus was cultured to log phase and spiked in Todd Hewitt(TH) broth and whole blood of healthy human volunteers. Viability of S. aureus after flucloxacillin treatment(0, 1, 3 and 6 d) was assessed by culture on bloodagar plates. DNA and RNA were isolated from 200 μL. c DNA synthesis was performed by using random primers. The presence of S. aureus DNA, r RNA, and m RNA were determined by real-time polymerase chain reaction of the 16 S r DNA and tuf gene(elongation factor Tu).RESULTS: S. aureus spiked in TH broth without antibiotics grew from day 0-6 and DNA(tuf and 16S), and 16 S r RNA remained detectable during this whole period. During flucloxacillin treatment S. aureus lost viability from day 3 onwards, while the 16 S r RNA-gene and its RNA transcripts remained detectable. DNA andr RNA can be detected in flucloxacillin treated S. aureus cultures that do not further contain culturable bacteria.However, tuf m RNA became undetectable from day 3onwards. Tuf m RNA can only be detected from samples with culturable bacteria. When spiking S. aureus in whole blood instead of broth no bacterial growth was seen, neither in the absence nor in the presence of flucloxacillin. Accordingly, no increase in DNA and RNA levels of both 16 S r DNA and the tuf gene were detected. CONCLUSION: Tuf m RNA expression is associated with culturable S. aureus and might be used to monitor antibiotic effects.展开更多
Pneumonia is a disease associated with significant healthcare burden with over 1.5 million hospitalizations annually and is the eighth leading cause of death in the United States.While community-acquired pneumonia(CAP...Pneumonia is a disease associated with significant healthcare burden with over 1.5 million hospitalizations annually and is the eighth leading cause of death in the United States.While community-acquired pneumonia(CAP)is generally considered an acute time-limited illness,it is associated with high long-term mortality,with nearly one-third of patients requiring hospitalization dying within one year.An increasing trend of detecting multidrug-resistant(MDR)organisms causing CAP has been observed,especially in the Western world.In this editorial,we discuss about a publication by Jatteppanavar et al which reported that a case of a MDR organism was the culprit in developing pneumonia,bacteremia,and infective endocarditis that led to the patient’s death.The early detection of these resistant organisms helps improve patient outcomes.Significant advances have been made in the biotechnological and research space,but preventive measures,diagnostic techniques,and treatment strategies need to be developed.展开更多
［1］Daniel JG, James RU, Cynthia A G, et al. Multiplex PCR for identification of methicillin-resistant staphylo-cocci in the clinical laboratory [J]. J Clin Microbiol,1994,32(7):1768［2］Chambers HF ,Sachdeva M. Bind...［1］Daniel JG, James RU, Cynthia A G, et al. Multiplex PCR for identification of methicillin-resistant staphylo-cocci in the clinical laboratory [J]. J Clin Microbiol,1994,32(7):1768［2］Chambers HF ,Sachdeva M. Binding of β-lactam antibi-otics to penicillin-binding proteins in methicillin-resis-tant staphylococcus aureus [J]. J Infect Dis, 1990,161:1170［3］Towner KJ,Talbot DC,Curran R, et al. Development and evaluation of a PCR-based immunoassay for the rapid detection of methicillin-resistant staphylococcus aureus[J]. J Med Microbiol, 1998,47 :607［4］Murakami KW, Minamide KW,Nakamura E, et al. I-dentification of methicillin-resistant strains of staphylo-cocci by polymerase chain reaction[J]. J Clin Microbiol,1991,29:2240［5］Hulimann-Dalel RL,Ryffel C, Kayser F H, et al. Sur-vey of the methicillin resistant -associated genes mecA,mecRI-mecI,and femA-femB in clinical isolates of me-thicillin-resistant Staphylococcus aureus[J]. Antimicrob Agents Chemother, 1992,36: 2617［6］Kopp U,Roos M ,Weck J, et al. Staphylococcal peptido-glycan interpeptide bridge biosynthesis: a novel anti-staphylococcal target[J]? Microb Drug Resist, 1996,2:29［7］Rychlik W, Spencer WJ,Rhoads R E. Optimization of the annealing temperature for DNA amplification in vitro [J]. Nucleic Acids Res, 1990,18 :展开更多
基金carried out with the support of "Cooperative Research Program for Agriculture Science & Technology Development(Project No.PJ01191902)" Rural Development Administration,Republic of Korea
文摘Objective: To investigate the synergistic effect between rhein(RHE) and oxacillin against Staphylococcus aureus(MRSA) at the gene level. Method: A minimum inhibitory concentration and checkerboard dilution test were conducted to evaluate antibacterial activity. Reverse transcriptase polymerase chain reaction was conducted to investigate the gene expressions. Results: RHE exhibited a minimum inhibitory concentration of 62.5-250.0 μg/mL against various MRSA strains and the reference strain, respectively. As revealed by the checkerboard assay, a combination of RHE and oxacillin exhibited synergistic or partially synergistic effects against MRSA strains. RHE decreased the expressions of mecA/blaZ in a dose-dependent manner. RHE also decreased the expressions of the regulator genes mecI/blaI and mecR1/blaR1. Conclusions: We suggest that RHE affects the activity of mecR1/blaR1, which is located in the cell membrane of MRSA and results in the suppression of mecA/mecI/mecR1 and blaZ/blaI/blaR1 gene expressions.
文摘AIM: To study the presence of various nucleic acids targets of Staphylococcus aureus(S. aureus) during bacterial growth and antibiotic induced killing in relation to viability.METHODS: S. aureus was cultured to log phase and spiked in Todd Hewitt(TH) broth and whole blood of healthy human volunteers. Viability of S. aureus after flucloxacillin treatment(0, 1, 3 and 6 d) was assessed by culture on bloodagar plates. DNA and RNA were isolated from 200 μL. c DNA synthesis was performed by using random primers. The presence of S. aureus DNA, r RNA, and m RNA were determined by real-time polymerase chain reaction of the 16 S r DNA and tuf gene(elongation factor Tu).RESULTS: S. aureus spiked in TH broth without antibiotics grew from day 0-6 and DNA(tuf and 16S), and 16 S r RNA remained detectable during this whole period. During flucloxacillin treatment S. aureus lost viability from day 3 onwards, while the 16 S r RNA-gene and its RNA transcripts remained detectable. DNA andr RNA can be detected in flucloxacillin treated S. aureus cultures that do not further contain culturable bacteria.However, tuf m RNA became undetectable from day 3onwards. Tuf m RNA can only be detected from samples with culturable bacteria. When spiking S. aureus in whole blood instead of broth no bacterial growth was seen, neither in the absence nor in the presence of flucloxacillin. Accordingly, no increase in DNA and RNA levels of both 16 S r DNA and the tuf gene were detected. CONCLUSION: Tuf m RNA expression is associated with culturable S. aureus and might be used to monitor antibiotic effects.
文摘Pneumonia is a disease associated with significant healthcare burden with over 1.5 million hospitalizations annually and is the eighth leading cause of death in the United States.While community-acquired pneumonia(CAP)is generally considered an acute time-limited illness,it is associated with high long-term mortality,with nearly one-third of patients requiring hospitalization dying within one year.An increasing trend of detecting multidrug-resistant(MDR)organisms causing CAP has been observed,especially in the Western world.In this editorial,we discuss about a publication by Jatteppanavar et al which reported that a case of a MDR organism was the culprit in developing pneumonia,bacteremia,and infective endocarditis that led to the patient’s death.The early detection of these resistant organisms helps improve patient outcomes.Significant advances have been made in the biotechnological and research space,but preventive measures,diagnostic techniques,and treatment strategies need to be developed.
基金This study was supported by the British Society for Antimicrobial Chemotherapy (BSAC)
文摘［1］Daniel JG, James RU, Cynthia A G, et al. Multiplex PCR for identification of methicillin-resistant staphylo-cocci in the clinical laboratory [J]. J Clin Microbiol,1994,32(7):1768［2］Chambers HF ,Sachdeva M. Binding of β-lactam antibi-otics to penicillin-binding proteins in methicillin-resis-tant staphylococcus aureus [J]. J Infect Dis, 1990,161:1170［3］Towner KJ,Talbot DC,Curran R, et al. Development and evaluation of a PCR-based immunoassay for the rapid detection of methicillin-resistant staphylococcus aureus[J]. J Med Microbiol, 1998,47 :607［4］Murakami KW, Minamide KW,Nakamura E, et al. I-dentification of methicillin-resistant strains of staphylo-cocci by polymerase chain reaction[J]. J Clin Microbiol,1991,29:2240［5］Hulimann-Dalel RL,Ryffel C, Kayser F H, et al. Sur-vey of the methicillin resistant -associated genes mecA,mecRI-mecI,and femA-femB in clinical isolates of me-thicillin-resistant Staphylococcus aureus[J]. Antimicrob Agents Chemother, 1992,36: 2617［6］Kopp U,Roos M ,Weck J, et al. Staphylococcal peptido-glycan interpeptide bridge biosynthesis: a novel anti-staphylococcal target[J]? Microb Drug Resist, 1996,2:29［7］Rychlik W, Spencer WJ,Rhoads R E. Optimization of the annealing temperature for DNA amplification in vitro [J]. Nucleic Acids Res, 1990,18 :
