Detection Of Resistance Genes And Homology Analysis Of Multi-drug Resistant Acinetobacter Baumannii

Objective:Acinetobacter baumannii(Ab)is a kind of non fermentative gram-negative bacilli,which is specialized in aerobic,unpowered and oxidase negative.At present,Ab has developed into one of the most common opportunistic pathogens of nosocomial infection,It is widely distributed in the air,water,soil and other natural environment,as well as ward,nurse station,doctor’s office and other hospital environment.It is very easy to cause hospital acquired pneumonia,urinary tract infection,septicemia and other serious and even fatal infections,especially in the intensive care unit.In recent years,due to the wide use of broad-spectrum antibiotics and the extensive development of invasive diagnosis and treatment technology,the detection rate of Acinetobacter baumannii is increasing,at the same time,the sensitivity of antibiotics is decreasing,the number of multi-drug resistant strains is increasing rapidly,and there is a serious phenomenon of clonal spread.How to control and treat multi-drug resistant Acinetobacter baumannii(MDRAB)infection has become a clinical problem to be solved urgently.The purpose of this study is to collect the clinical distribution and drug resistance data of multiple Acinetobacter baumannii in Yan’an Hospital Affiliated to Kunming Medical University(hereinafter referred to as our hospital),describe the carrying situation of related drug resistance genes,and clarify the relationship between strains through molecular epidemiological investigation,so as to provide reliable and timely epidemiological data,guide the clinical development of reasonable and effective drug use strategies,and improve patients cure rate,provide a laboratory basis for the hospital to formulate strong infection prevention and control measures and control the outbreak of Acinetobacter baumannii.Method:A total of 100 strains of non repetitive and multi-drug resistant Acinetobacter baumannii isolated from the laboratory of Yan’an Hospital Affiliated to Kunming Medical University from September 2017 to December 2018 were collected,and identified by vitek2-compact automatic microbial analyzer.The sensitivity of Acinetobacter baumannii to commonly used clinical antibiotics was detected by MIC and K-B methods,and 7 kinds of β-lactamase resistance genes(SHV,TEM,IMP,VIM,ADC,OXA-23,OXA-58)were detected by polymerase chain reaction(PCR),Multilocus sequence typing(MLST)was used to perform molecular typing on 38 randomly selected multi-drug resistant Acinetobacter baumannii strains and analyze the homology relationship of strains.Results:(1)Clinical distribution of strains:100 strains of multi-drug resistant Acinetobacter baumannii were mainly from neurosurgery,accounting for 40%,followed by the Department of Intensive Medicine,accounting for 23%,respiratory medicine accounted for 18%,cardiac surgery ICU,rehabilitation department,general surgery and orthopedics accounted for 5%,4%,3%,3%respectively;Specimens mainly consisted of sputum samples(59%)and alveolar lavage fluid(33%),wound secretions accounted for 4%,and blood,urine,cerebrospinal fluid,and pleural fluid samples each accounted for 1%.(2)Drug resistance distribution:100 strains of Acinetobacter baumannii with multiple drug resistance were all highly resistant to the detected antibiotics,and the resistance rate to penicillins,monocyclic β-lactams,cephalosporins and carbapenems was as high as 100%;among β-lactamase inhibitors,except for the cefoperazone/sulbactam resistance rate of 87%,the resistance rates of the remaining β-lactam inhibitors are all 100%;The drug resistance rates of dynomycin and levofloxacin were up to 96%and 94%respectively;the drug resistance rates of tobramycin,co-trimoxazole and amikacin were all 91%;the drug resistance rates of minocycline were more than 50%,with a high intermediary rate;the drug resistance rates of only tegacyclin were 0%.(3)Distribution of drug resistance genes:Among 100 strains of multi-drug resistant Acinetobacter baumannii,the detection rate of TEM gene was the highest,with a total of 94 strains positive,followed by the OXA-23 gene,accounting for 92%,82 strains carried the ADC gene(82%),and SHV,IMP,VIM,OXA-58 genes were not detected.75 strains carried TEM+ADC+OXA-23 gene at the same time,14 strains carried TEM+OXA-23 gene,4 strains carried TEM+ADC gene,2 strains carried ADC+OXA-23 gene,separate TEM,ADC,OXA-23 genes there were 1 strain each positive,and the other 2 strains were negative for the above 7 genes.(4)Homology analysis:38 strains of multi-drug resistant Acinetobacter baumannii were sequenced and submitted to pubmlst database for comparison.The results were divided into 5 sequence types,of which more than half were ST208 type(55.3%),which was the dominant type,followed by ST1145 type,Accounting for 31.5%,ST540 type,ST195 type and ST1696 type had 2 strains,2 strains,1 strain,accounting for 5.3%,5.3%and 2.6%,respectively.The ST208 type was distributed in the Department of Intensive Medicine,Neurosurgery,Respiratory Medicine,Thoracic Surgery,Cardiac Surgery,and Neurology.The ST1145 type was also examined in the Department of Neurosurgery,Intensive Medicine,Respiratory Medicine,General Surgery,Rehabilitation,and Nephrology.Conclusion:(1)The multi-drug resistant Acinetobacter baumannii is widely distributed in our hospital,mainly from neurosurgery and intensive care.It mainly causes respiratory tract infection in patients.(2)The clinical isolation of Acinetobacter baumannii is severely resistant and generally resistant to various types of antibiotics.A few strains are sensitive to Cefoperazone/sulbactam and minocycline,and all strains are not resistant to tegacyclin,which suggests that tegacyclin has a wide application prospect as a treatment drug of Acinetobacter baumannii infection.(3)Carrying TEM,ADC and OXA-23 genes is an important reason for the resistance of Acinetobacter baumannii to β-lactams in our hospital,while carrying TEM+ADC+OXA-23 gene at the same time is the most important resistance mode of Acinetobacter baumannii.(4)Multilocus sequence typing of Acinetobacter baumannii found that ST208 type is the most common sequence type in our hospital.ST208 type and ST1145 type are widely distributed among various departments of the hospital,and there is clonal transmission of drug resistant strains.