| ObjectiveInvestigate the presence of carbapenem-resistant Escherichia coli or colistin-resistant Escherichia coli in clinical isolates of E.coli from certain livestock farms in Tai’an area and Tai’an Central Hospital from July 2015 to December 2017 Whether the bacteria drug-resistant strains carry the gene for NDM-1 or mcr-1,respectively,and screen for the presence of other drug resistance genes.This study intends to use Escherichia coli as the research object,initially expounding its epidemic characteristics and transmission rules in chickens,ducks and humans,the characteristics of drug resistance and the genetic basis of the virulence diversity of pathogenic bacteria.Disease prevention provides a theoretical basis.MethodThis study focused on the collection of 87 E.coli isolates from several livest-ock and poultry farms in Tai’an City.Among them,a non-repetitive carbapenem-resistant E.coli was screened out,and non-repetitive polymyxin-resistant E.coli were screened out.There were 27 strains of Escherichia coli clinically isolated in Tai’an Central Hospital,and 16 non-repeated carbapenem-resistant E.coli bacteria.At present,no colistin resistant E.coli has been detected in clinical specimens.For drug r-esistant bacteria,we used the Autof ms 1000 mass spectrometer to redetermine that the strains were all Escherichia coli.At the same time,we used the paper diffusionmethod,automatic susceptibility identification method(Siemens microscan96plus,BDPHOENIXTM System and Merieux VITEK(?)2 COMPACT III(Automated microbi-ological analysis system)and E-test method for measuring strains of polymyxin,imi-penem,meropenem,ertapenem,aztreonam,amikacin,levofloxacin,gentamycin,and compound The sensitivity of sulfamethoxazole,piperacillin tazobactam,cefotaxi-me,ceftazidime,cefepime,cefoxitin and other antimicrobial agents.Using the modi-fied Hodge experiment and EDTA codiffusion experiment to detect the occurrence of ca-rbapenemase in 17 strains of bacteria.Then,polymerase chain reaction(PCR)was used to detect the resistant genes of the strain(polymyxin resistance gene,carbape-nemase gene,extended-spectrum β-lactam resistance gene,aminoglycoside resistance gene,Quinolone-resistance genes)Whether the tested strains carry NDM-1 or mcr-1 drug resistance genes and carry other drug resistance genes at the same time,and carry out drug gene sequencing of the experimental strains,and use whole genome sequencing(shotgun method)Drug resistance genes are verified.Pulsed-field gel-electrophoresis(PFGE)and multilocus sequence typing(MLST)were used to analyze the homology between poultry and poultry,human and human,poultry and humans,and to use multilocus sequence typing(MLST)for bacterial typing and evolutionaryanalysis.Through junctional experiments,it was tested whether the resistant genes could be spread horizontally through plasmids.ResultWe and our partners have isolated 87 E.coli strains from several livestock and poultry farms in the region,and one strain of carbapenem-resistant Escherichia coli,which is derived from the lung tissue of chickens;A total of 16 non-repeated carbapenem-resistant E.coli strains were screened out in the specimens,of which 2 were from neurosurgeons,2 were from general surgical wards,2 were from infants 3 and 2 were from neurology department.The intensive care unit and others were from the Department of Pediatrics PICU,General Surgery Western Ward,Department of Critical Care Ward,Eastern Trauma Department of Traumatic Hand and Foot Surgery,Severe Respiratory Diseases,Gynecological Second Ward Ward,Digestive Second Disease Ward,and Rehabilitation Ward.Drug sensitivity experiments showed that 17 strains of bacteria were resistant to carbapenem drugs,and 17 strains of bacteria were both positive for Hodge and EDTA.And through the resistance gene screening,2 of them were found to contain blaNDM-1 gene,and the remaining 15 contained blaNDM-5 gene.The detection of other drug resistance genes is not described here.PFGE found that 17 strains of bacteria belonged to different types of spectrum,with 85%being the boundary.Multilocus sequence typing(MLST)confirmed that these 17 strains belonged to ST10,ST167,ST405,ST767,ST408,ST1284,ST2491,ST6082.The results of pulsed-field gel electrophoresis and MLST analysis have not yet found outbreaks on a large scale..Of the 17 strains of bacteria,13 strains were successfully ligated,and some of the bacterial resistance genes were successfully transmitted.We and our partners have separated 87 E.coli bacteria and 27 strains of polymyxin-resistant E.coli from several livestock and poultry farms in the region.These 27 strains are derived from chicken/duck lung tissue and have drug sensitivity Experiments showed that the bacteria were all resistant to polymyxin drugs.The drug-resistance gene was found to contain blaMCR-1 gene.Multilocus sequence typing(MLST)confirmed that these 27 strains belong to ST767,ST155,ST457,ST48,ST4204,ST533,ST1638,ST101,ST6395,ST4408,ST1968,ST117,ST156,ST23,ST10,ST5912 type.PFGE found that 27 strains of bacteria belonged to different typ-es of spectrum Based on the 85%similarity standard,they could be divided into 15 different bands.The homology of the isolates of different diseased chickens andducks ranged from 67.1%to 100%.There were higher homologous specimens amo-ng the strains,but no absolute dominant bands were found on the whole,indicatingthat the strains were polymorphic at the genetic level.Of the 27 strains of bacteria,13 strains were successfully ligated and some of the bacterial resistance genes weresuccessfully transmittedconclusionIt was confirmed that the main resistance factor of carbapenem-resistant Esche-richia coli in this region is due to the "New Delhi metal-β-lactamase" gene,which can be transmitted from one another between bacteria and cause drug resistance tra-nsmission Both humans and chickens are found and can be spread among differentspeciesThe presence of polymyxin E.coli in poultry in the Tai’an region accounts for 31%,confirming that the main drug resistance factor is due to the blamcr-1 gene.Even if it was not found in Tai’an region,this drug-resistant gene can be transmitt-ed between bacteria Passed between,resulting in the transmission of drug resistance. |
