Distribution Characteristics And Drug Resistance Of Clinical Pathogens In A New General Hospital

Objective:XX hospital is built according to the scale of public tertiary comprehensive hospitals,This Hospital was officially put into use on May 18,2016.In the past,there were few studies on the distribution and drug resistance of pathogens in newly-built large public hospitals.Through a series of experiments,this study explored the homology,drug resistance mechanism,epidemic trend,infection distribution characteristics,etc.among strains in the new hospital environment.for the sake of monitoring and analysingof drug resistance of nosocomial bacteria and the rational use of antibiotics in clinical treatment.The objective of this study was to lay a theoretical foundation for the prevention and control of the prevalence of multi-drug resistant strains,especially carbapenem-resistant Enterobacteriaceae in hospital.Methods:Distribution and drug resistance of clinical pathogenic bacteria1.From November 2017 to April 2018,strains of clinical bacteria were cultured and identified by BD Phoenix-100 System automatic microbial analyzer in the Microbiology Department of XX Hospital.All of them came from clinical specimens.2.The strain species,specimen types,drug resistance phenotypes and clinical distribution of the main pathogenic bacteria were analyzed by WHONET 5.4 software.Molecular characteristics of Escherichia coli and Klebsiella pneumoniae1.Strain identification and antimicrobial susceptibility testing were identified by BD Phoenix-100 automatic microbial analyzer.K-B method of Imipenem and meropenem were performed to identify the carbapenem-resistant Enterobacteriaceae(Carbapenem-Resistant Enterobacteriaceae,CRE)by The isolates were further identified by MALDI-TOF-MS(matrix assisted laser desorption ionization time of flight mass spectrometry).2 Pulsed-field gel electrophoresis(pulsed-field gel electrophoresis,PFGE)analysis were performed to analyze epidemiology of Escherichia coli,Klebsiella pneumoniae clinical isolates.3 All isolates that exhibited resistance to carbapenem(imipenem or meropenem)were screened for presence of the resistance genes including blamcr-1,blaKPC,blaNDM,blaVIM,blaIMP,bla OXA-48 by polymerase chain reaction(Polymerase chain reaction,PCR).4 Whole genome sequencing:Klebsiella pneumoniae carrying bla KPC was selected for genome-wide sequence analysis.5 Plasmid conjugation transfer test:The selected carbapenemase-producing donors and recipients were mixed for conjugation experiment,and then the positive conjugation were screened by PCR.The carrying status of the conjugative transfer plasmid was analyzed by S1-PFGE assay.Molecular characteristics of Staphylococcus aureus1.Strain identification and drug sensitivity analysis:Bacterial identification was performed using BD Phoenix-100 System automatic microbiological analyzer,and reviewed by MALDI-TOF-MS.2.Pulse field gel electrophoresis analysis:Some strains were analyzed by PFGE technique,and the criterion was:the similarity>85%was the same clone.To study the epidemiological relevance of clinical isolates of S.aureus.3.The S.aureus virulence genes pvl and tst were detected by PCR.Results:Distribution and drug resistance of clinical pathogenic bacteria1.A total of 1477 positive non-repetitive bacteria were isolated from 7023 specimens.Among them,325 were gram-negative bacteria and.300 were gram-positive bacteria The higher detection rate was wound secretion,sputum and urine,and the higher detection rate of pathogenic bacteria was neurosurgery,obstetrics,respiratory medicine,urology,general surgery,digestive medicine,orthopaedics and so on.2.Escherichia coli were predominate gram-negative bacteria isolates followed by Klebsiella pneumoniae,Pseudomonas aeruginosa,Enterobacter cloacae,Acinetobacter baumannii and Klebsiella acidogenicus.Staphylococcus aureus were predominate Gram-positive bacteria isolates followed by Streptococcus agalactis,Staphylococcus haemolyticus,Enterococcus faecalis and Staphylococcus epidermidis.3.Analysis of drug resistance of major pathogens,among Gram-negative bacteria,Escherichia coli and Klebsiella pneumoniae have higher resistance rates to first-generation cephalosporins cefazolin,to carbapenems,most The resistance rate of β-lactam antibiotics is low.Gram-positive bacteria in Staphylococcus aureus have higher resistance rate to penicillin and erythromycin,lower resistance to linezolid,teicoplanin and amikacin,and no resistance to vancomycin.Strain.4.Analysis of multi-drug resistant bacteria,12 strains of carbapenem-resistant Enterobacteriaceae(CRE),mainly Klebsiella pneumoniae and Escherichia coli.Carbapenem-resistant Pseudomonas aeruginosa(CRPA)accounted for 25%,carbapenem-resistant Acinetobacter baumannii(CR-AB)accounted for 84%,methicillin-resistant Staphylococcus aureus(MRSA))accounted for 38.32%,and vancomycin-resistant enterococci(VRE)accounted for 5%.Molecular characteristics of Escherichia coli and Klebsiella pneumoniae1.The PFGE results of 69 strains of Escherichia coli showed that there were 7 clones of the seven strains,and the PFGE results of 47 strains of Klebsiella pneumoniae showed that there were 4 clones with 4 strains.Clinical data show that these strains are from different departments in different time periods,with a small amount of scattered distribution.2.Eight CRE strains were detected to carry carbapenemase gene by PCR.Four of them carried blaNDM,one blaIMP,one blaKPC and two blaNDM and blaIMP.3.The genome-wide sequence analysis of a strain of Klebsiella pneumoniae carrying bla KPC showed that KPC-2 was the main drug resistance gene classification.It is ST11 typing.4.In conjugation transfer experiment,two strains of Escherichia coli carrying NDM gene and one strain of Klebsiella pneumoniae carrying KPC gene were successfully conjugated and transferred.and the suspected junction-transfer resistance gene was detected by PCR.A plasmid zygote carrying the corresponding carbapenemase gene.A part of the plasmid was combined with the transferor for PFGE experiments,and the endonuclease was used to digest the plasmid S1.The PFGE results showed that the three strains of the binding gene had plasmids carrying the resistance gene.Molecular characteristics of Staphylococcus aureu1 The PFGE results of 32 strains of Staphylococcus aureus showed that there were four groups of strains of the same clonal type,and one group of three strains were obtained from the general surgical specimens of the same period of time,and the rest were scattered.2.The positive rates of the virulence genes pvl and tst of Staphylococcus aureus were 25%.Two of them carry both the tst and pvl genes.Conclusion:1.The distribution and drug resistance of clinical isolates in this hospital are mostly similar to those in other medical units.At the same time,it has unique distribution characteristics in the new hospital environment.2.The results of homology analysis of Escherichia coli and Klebsiella pneumoniae strains showed no major clonotypes,and only a small range of clones were possible.The homology analysis of some strains of Staphylococcus aureus showed that there were clones in the same department and at the same time.3.The resistance genes of carbapenem-resistant Enterobacteriaceae in our hospital are diverse,and the resistance situation is not optimistic.4 The carrying rate of Staphylococcus aureus virulence gene tst,pvl is at a relatively high level,should be paid attention to in the process of clinical anti-infective treatment.5.New large-scale integrated public hospitals should be strictly controlled at the beginning of their use.It is recommended to supervise multiple departments to strengthen the rational use of antibiotics,effectively curb bacterial resistance and prevent hospital infections.