Study On The Relationship Between Staphylococcus Resistance Gene Polymorphism And Diseases In Neonatal Lower Respiratory Tract Infection

Respiratory tract infections(RTI)is the most common highly infectious disease in hospitals,which is often accompanied by influenza and influenza like diseases.The annual incidence rate and mortality rate make respiratory tract infection a global problem.Respiratory tract was initially considered to be sterile,but with the discovery of research,there are a large number of symbiotic microorganisms in respiratory tract,which has a great impact on human health.When human beings are in normal physiological state,symbiotic bacteria in respiratory tract restrict each other to maintain a relative balance.For newborns,this homeostasis is affected by the mode of production,type of feeding,antibiotics,etc.,but once this balance is destroyed,it will cause the disorder of respiratory tract microorganisms,and then induce respiratory tract infection and other related diseases.At present,the most commonly used method for respiratory tract infection is the use of antibiotics.Because of the long time,unreasonable use and abuse of antibiotics,a series of drug-resistant bacteria are produced,which greatly increases the burden of clinical treatment and social economy.The use of appropriate antibiotics for the treatment of infection is a very important step,can reduce the occurrence of drug resistance and even death.Therefore,for respiratory tract infection,especially drug-resistant bacteria infection,the choice and dosage of antibiotics is particularly important.The purpose of this project is to study the microbial community structure of lower respiratory tract in patients with respiratory tract infection and the comparative law of microbial composition between infected people and healthy people,isolate and culture pathogenic bacteria from them,and select some isolated Staphylococcus to explore their drug resistance and clarify the distribution of drug resistance.And the detection of drug resistance genes,using co culture means to explore the transfer of drug resistance genes.The main contents and experimental results are as follows.21 newborns,including 19 patients with respiratory tract infection and 2 healthy newborns,were selected to collect feces and trachea secretion.The microbial community structure was analyzed based on α diversity and β-diversity.In this experiment,Proteobacteria,Fixitutes and Actinobcteria gate are the dominant Phylum at the Phylum level.At the level of genus,the distribution of bacterial genera was different among patients.Among all fecal samples,the fecal samples of the sick newborn mainly belonged to Enterococcus and Achromobacter,followed by Lactobacillus and Pantoea,and Achromobacter and Streptoccus in all the samples of tracheal secretion,followed by Pseudomonas,Rothia and Staphylococcus.116 strains were isolated from patients with lower respiratory tract infection,including 53 strains of Staphylococcus epidermidis,1 strain of Staphylococcus aureus,4 strains of Staphylococcus cohnii,9 strains of Staphylococcus hominis,14 strains of Staphylococcus haemolyticus,1 strain of Staphylococcus caprae,1 strain of Staphylococcus warneri / pasteuri and 2 strains of Streptococcus thermophilus,15 Streptococcus salivarius,3 Moraxella osloensis,10 Lactobacillus plantarum,2 Micrococcus yunnanensis and 1 Micrococcus luteus.K-B disk diffusion method was used to detect the drug resistance of 83 strains of Staphylococcus.The results showed that 83 Staphylococcus isolates had the highest resistance rate to Penicillin(84.34%),followed by Erythromycin(57.83%),and the other resistance rates were Oxacillin(8.43%),Ciprofloxacin(13.00%),Vancomycin(4.82%),Ofloxacin(14.46%),Chloramphenicol(43.37%),Kanamycin(38.85%),Clindamycin(14.46%),Cephalosporin(14.46%)Azolin(16.87%)and Rifampicin(8.43%).The results showed that the positive rate of grl A was the highest(51.95%),followed by aac(6’)/aph(2’’)gene(31.17%).The positive rates of other drug resistance genes from high to low were gyr A(27.27%),mec A(23.88%),nor A(16.88%)and erm C(16.88%).fem A(9.09%),erm A(7.79%)。 However,Van A and Van B genes were not detected in these isolates.The results showed that Staphylococcus epidermidis could transfer drug-resistant genes to the same genus of Staphylococcus,such as Staphylococcus cohnii,and to different genera,such as Lactobacillus plantarum.