| Antibacterial or antibicrtics were widely used in dinical veterinary to cure bacterial infections or improve the growth of animals in China.However,With the wide utilization of antibacterial,common clinical pathogenic bacterium including of Escherichia coli can give drug resistance,which have been found increasing gradually evey year.The remarkable to ing is mostof the resistance are multidrug-resistance or cross-resistance.There were many factors which resulted in multidrug-resistance.And active efflux pump resistance mechanism was to e commonest one.OgjcAff gene which was found in 2004 could code active efflux pump and reduce many drugs sensitivity,such as olaquindox,FQNS and amphenicols,and so on,which can mediate multiple drug resistance and oppose general substrates.It has been rqjorted that oqxAB genes mainly prevailed in Enterobacteriaceae such as E.coli ,klebsiella pneumonis and salmonella.Maybe resulted from massive application of quinoxaline as a kind of antibiotic growth promoter in the clinical veterinary.stwas also found in strains isolated from human and was infered that oqxAB genes induced by application boundless of quinoxaline horizontal transfored U)the isolates from human via food chains.It was just classified among Plasmid-mediated quinolone resistance gene(PMQR),attached to Resistance nodulation cell division(RND).It wascoded mainly by plasmid and could horizontally transmit among different bacterial and enhanced the widespread prevalence of oqxAB gene.But,the studys about active effluxpump oqxAB gene were just in the beginning and severe scarce.So,a series of studies were performed in to is paper,as follow:1.More than 200 pathogenic bacterium samples from to fferent farms in Zhengzhou,Jiaozuo, Dengfeng, Jiyuan, were isolated and identified with VITEK-32 system. 136 isolates of of E coli were collected from animals,including 53 strains from pets,32 strains ftoni rabbits,25 strains from ostrich,22 strains from(hicks and 4 strains from cats. In ad to tion,50 isolates human pathogenic bacterium in Henan province were collected from Henan people,s hospital. 186 isolates of clinical E. coli were collected and separated. MIC of 186 isolates to the drugs including P-lactams(Ceftiofiir, Ceftiofur /Sulbactam, Ceftriaxone), quinoxaline(Olaquindox, Mequindox),Amphenicols(Florfenicol), FQNS(Ciprofloxacin,Gatinoxacin),Aminoglycosides(Amikacin), polymyxins(polymyxi.E) and Tetracychnes(Tetracycline,Doxycycline) were estimated with microdilution.Multidrug resistance phenotypes were compared and analyzed. The results showed that 27.3%~92.0% E CO to from animals resisted the third generation cephalosporin. More than 96% isolates resisted four and above kinds drugs. The most serious was that they could resist 9 kinds of drugs. 14.81% E. coli fromrabbits are resistant to more than 9 kinds of drugs and 40% E. coli from ostriches are resistant to 9 kinds of drugs. This were not found in strains from ducks and dogs.Multidrug-resistance of 50 isolates from human were more serious. More than 80.750/oisolates resis1:ed 8 and above kinds of drags. The commonest was that which resisted 9 kinds of drugs, accounting for 34.61%. The rate of resistance to Olaquindox,Mlaquindox were38.5%, 27.0%, respectively.2.oqxAB gene prevalence was estimated. The result showed that the positive rate of oqxAB gene of E. coli from dogs was highest(100%). Second was E. coli from rabbits(82.1%), The positive rate of E. coli from ostrich was closed to that from cat, were 76%and 75%, respectively. The lowest positive rate was that from duck, it was 45.5%. The oqxB-positive strain was found from duck not carrying oqxA which deserves furtherresearch. The positive rate of oqxAB of E. coli from human was 64%, which was higher than that from duck and was lower than s to ains from o to er animals. It was the first time to investigate and reportgene of E. coli from ortrich,rabitt,dog and cat. The fbll sequence of oqxAB gene were successfully gained and were deposited in GenBank under the accession no.(JX429863, JX294475, JX442218, JX 412478, JX 469117). The upstream ofAB gene of one isolate(Tl) of E. coli from ostrich and one(H050) from human was linked with insert sequence IS26 and ISEcpl. The sequence was deposited in GenBank under to e accession no. yX429863 and JX 469117).3.30 representative strains were typed systematically with ERIC- PCR、MLST and Phylogeny evolution classification(Clermont et al,2000). Nine kinds of E R IC-PCR showed to at 8 isolates(26.7%) belonged U) genotype III, 7 isolates u3.3%),5 isolates(16.7%),4isolates(13.3%) belonged to genotype 1,V1 and VIIL respectively. One group of E. coli from different hosts(Iisolate from rabbit,3 isolatas from human and one isolate from dog)belonged to the same clone source. Semblance of ER 1C- PCR fragments were extremely high, another group of s to ains from different hosts(1 from dog and 1 from human) was the same group. 181 isolates were estimat;ed with phylogeny evolution typing.Results showed that 38 isolates belonged to D group and 5 strains from dog st.(4%),3 strains from rabbit(0.71%),3 strains from ostridi(2.0%),9 strains from duck(40.9%),18 strains from human (6%) and none of to em from cat. 47 isolates belonged to B2 group. 14 strains from dog u4.4%),none of them from rabbit,13 strains from ostrichu(2.0%),4 strains from duck(18.2%) and 16 strains from human(2%). The rest of them belonged to group A and B1. The isolates which belonged to group D and B2 were thought to be pathogenk.MLST classistcation result showed that there were 17 ST types of 30 isolates from different hosts. 9 new ST sequences were found. The result with MLST corresponded to ERIC-PCR.E. coli from to fferent hosts(1 from dog and 1 from cat,1 from human and 1from dog) have same ST type. This indicated to at oqxAB was transmitted not only by done,but also by other ways.4.oqxAB gene were positioned by plasmids cx)njugation experiment and Southem-Blot.8 E. coli conjugant were gained successfully, 3 strains from duck,others all was 1 isolate,indicating that ogx45 gene located in plasmid which could be conjugated and transferred.Drug sensitivity to St of conjugants showed that 68% conjugant transmit to e resistance to of Ciprofloxacin,Florfenicol,Olaquindox, and Gatifloxacin. Southem-Blot result showed that oqxAB gene from E. coli Ml7, T1 and R20 existed not only in plasmid which was >50-108 kb, but also located in chromogene. OqxAB gene was found only in the chromosome of E. coli Q1 from dog and E. coH H029 from human.5.The investigation study of transmission mechanism showed that enterobacteriaceae common insert sequence ISEcpl and IS26 existed extensively in 6 kinds of E. coli.Dstection rates of ISEcpl in E. coli from duck was 22.2%,E. coli from ostrich was 80.3%,E.coli from dog was 10.2%, E. coli from rabbit was 75%, E. coli from human was 16%.Detection rates of IS26 were 33.3%、88.0%、25.6%、5% in turn. ISEcpl and IS26 were not dstected in E. coli from cat. it indicated that oqxAB could be transmitted and transferred with transposon or integron by plasmid. to could also be transferred with chromosome to plasmid by integration and could transmit among diiferent species of bacterium. |
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