| The abuse of antibiotics has led to the emergence of superbacteria.A variety of multidrug-resistant bacteria that can not be effectively treated have emerged,which greatly threatens human health and is a major problem facing all mankind.At the G20 Summit in 2016,the topic of antibiotic resistance has risen to an international level,becoming a worldwide problem equivalent to climate change and terrorism.Although new antibiotics have been developed to resist drug-resistant bacteria,due to the long research cycle,great difficulty and high research cost,progress has been slow.What's more,many antibiotics have not yet been found on the market.Drug-resistant bacteria,so relying solely on the development of new antibiotics can not effectively curb the process of bacterial resistance in a timely manner.Therefore,it is the most economical and rapid strategy to reverse the resistance of bacteria and restore the sensitivity of resistant bacteria to antibiotics.Traditional Chinese medicine plays an important role in modern prevention and control of bacterial infections.At present,it has been found that traditional Chinese medicines such as heat-clearing and detoxification,heat-clearing and Dampness-drying have antimicrobial and reversing drug resistance.For example,Luyajun etal.studied that Sanhuang Decoction,Huanglian Detoxification Decoction and Wuwei Disinfectant Drink can partly or completely reverse the sensitivity of Escherichia coli producing extended-spectrum ?-lactamase to antibiotics.Tanreqing injection mainly includes Scutellaria baicalensis,bear bile powder,goat horn,honeysuckle and Forsythia suspensa.It belongs to the compound preparation of traditional Chinese medicine.It has the functions of clearing heat and resolving phlegm,anti-bacteria and enhancing immunity.It is mainly used to treat respiratory tract infections caused by respiratory pathogens(Staphylococcus aureus,Dicoccus pneumoniae,etc.).Staphylococcus aureus is the main pathogen.The United States Centers for Disease Control(CDC)reported that Staphylococcus aureus was the second most common cause of infection,after Escherichia coli.With the widespread use of antibiotics,the number of methicillin-resistant Staphylococcus aureus(MRSA)has increased dramatically.The prevalence of MRSA is a serious clinical and public health problem.The number of deaths caused by MRSA infection in the United States each year is equivalent to the sum of AIDS,Tuberculosis and Viral Hepatitis(AVH).The above-mentioned Tanreqing injection is symptomatic for the treatment of respiratory tract infection caused by Staphylococcus aureus.Therefore,it is feasible and necessary to use Tanreqing injection to resist and reverse the drug resistance of Staphylococcus aureus.The basis of our previous work indicates that Tanreqing has a synergistic effect on inhibiting the formation of MRSA bacterial biofilm and synergistic effect with antibiotic vancomycin,but further research is needed on whether it can change the resistance of MRSA.Therefore,in this study we observed its resistance reversal to clinically derived MRSA.This study is mainly divided into four parts.The reversal effect of TRQ(TanReQing)on MRSA resistance is discussed from the perspective of phenotype and drug resistance gene.Phenotypic Study-Reversal Effect of Tanreqing Injection on Clinical Isolation of Resistant Bacteria(MRSA)In this experiment,we mainly used MIC(Medium Interface Connector)value to characterize the changes of drug resistance before and after reversal of clinical MRSA isolates.High MIC value indicates strong drug resistance,whereas weak or non-drug resistance.Therefore,using MIC value can indicate whether TRQ has reversal effect.2.Study on genetic stability of Tanreqing-induced reversal of clinical isolates of drug-resistant bacteriaWhen TRQ reverses the effect of clinical isolation of MRSA,the main problem is the study of its genetic stability.To solve this problem,we carried out two studies: continuous blank culture for 10 generations and repeated induction of antibiotics for 5 generations.According to the observation of MIC changes,we determined its genetic stability.If there is no significant difference in MIC values after 10 generations of continuous blank culture and before and after 5 generations of antibiotic-induced resistance.It is proved that reversal has genetic stability.3.Exploring the mechanism of resistance genes in drug-resistant bacteria by gene detectionThe causes of MRSA resistance can be divided into acquired resistance and intrinsic resistance.These two sources can not be separated from the transformation or mediation of DNA,that is,the changes of related genes.Therefore,the mechanism can be explored by monitoring the changes of genes in strains before and after reversion.4.The mechanism of drug-resistant genes in drug-resistant bacteria was discussed by molecular cloning technology.Based on the experimental results of the aforementioned resistance genes,we selected several aminoglycoside-resistant antibiotic genes and studied them in detail by molecular cloning technology.The results showed that in phenotypic experiments,the MIC values of clinical isolates of MRSA after reversion were significantly lower than those before reversion,especially for aminoglycoside antibiotics.In further mechanism studies,before and after induction reversion,multiple drug resistance genes changed,disappeared or decreased.When aacA gene was introduced into competent cells by molecular cloning technology,the phenotype(MICs)of aacA increased,suggesting that clinical MRSA resistance is related to the resistance gene.To sum up,Tanreqing injection can induce reverse effect on clinical isolation of MRSA,and reduce drug resistance by altering some drug-resistant genes.It provides new methods and ideas for clinical bacterial infectious diseases caused by drug-resistant bacteria,guides clinical medication selection(improving cure rate,reducing mortality,etc.),optimizes the use of antibiotics,and explores the mechanism-based approach.It is conducive to the development of new drugs and so on. |
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