Study On Molecular Epidemiology And Expression Of Outer Membrane Proteins Of Acinetobacter Baumannii In Pediatrics

Objective The purpose of this study was to analyze the resistance and molecular typing of Acinetobacter baumannii and the expression of outer membrane proteins(OmpA and OmpW)of different genotypes in pediatric patients,in order to further elucidate the separation of Baumann in pediatric patients.The intracellular transmission characteristics of Bacillus and the possible mechanism of action of outer membrane proteins provide new experimental and theoretical basis.Methods The pediatric inpatients in our hospital were used as screening targets,and the isolates of Acinetobacter baumannii in hospitalized pediatric patients were used as research objects from January 1st,2017 to June 30 th,2018.The distribution and drug resistance of Acinetobacter baumannii isolates were detected dynamically by bacterial identification and drug susceptibility test.The homology analysis was carried out by two kinds of molecular typing methods: pulse field gel electrophoresis(PFGE)and multi-site sequence analysis(MLST).The mRNA expression levels of outer membrane protein A(OmpA)and outer membrane protein W(OmpW)of Acinetobacter baumannii clones were detected by RT-PCR.Results 1.The study screened2,200 pediatric patient,A total of 57 clinical isolates of Acinetobacter baumannii were collected,of which42 were from pediatric patient isolates and 15 were from pediatric patient environmental isolates.The positive rate of positive pediatric patient was low(42/2200,1.9%),and the positive rate of positive pediatric patient surrounding environment in our hospital was also low(4/42,9.5%),the highest resistance rate to ceftriaxone and nitrofurantoin(100%),followed by cefepime(11.9%),and the resistance rate to imipenem and meropenem was lower(both 7.1%),but sensitive to tegacycline(0%).2.Homology analysis:(1)PFGE typing showed that 42 isolates were divided into 40 genotypes(X1~X40),of which X31(3strains,7.14%)were dominant clones,and the remaining clinical isolates were non-dominant clones;(2)MLST typing results showed that 40 genotypes were divided into 30 ST types,of which X31 was ST-705 and belonged to CC92 clonal group;The ST genotyping of the children with isolates A34 and A38 were consistent with that of their environmental isolates,but the children with isolates A37 and A42 were inconsistent with their environmental isolates.3.The median relative mRNA expression of 42 strains of Acinetobacter baumannii OmpA was significantly higher than that of OmpW(7.6064,0.6315,P < 0.05),and the median relative expression of OmpA was significantly higher.The median relative expression of mRNA of non-dominant clones and dominant clone OmpW was basically the same as that of non-dominant clones.Conclusions 1.The resistancerate of Acinetobacter baumannii isolates to imipenem and meropenem in our hospital is low(4/42,7.1%).2.The genotyping of Acinetobacter baumannii isolates showed diversity characteristics,and the dominant clones were mainly ST705.3.The median relative expression of OmpA-encoding mRNA of Acinetobacter baumannii isolates was significantly higher than that of OmpW(7.6064 vs 0.6315),which may be the major virulence factor of Acinetobacter baumannii.