Investigation of resistant genes in pandrug-resistant Acinetobacter baumannii isolated from Ningbo, Zhejiang Province

OBJECTIVE To investigate the conditions and phylogenetic analysis among agroup of pandrug-resistant Acinetobacter baumannii（A.Baumannii）.METHODS A total of 33 strains of pandrug-resistant A.baumannii from Jan.2013 to Dec.2013 were collected from the affiliated hospital of school of medicine of Ningbo University.Then,resistance genes were analyzed by PCR,including 33 kinds of beta-lactamase genes,3kinds of linkage detection of beta-lactamase genes and insertion sequences,14 kinds of resistant genes to aminoglycosides,1kind of resistant genes to quinolones,and 1kind of acquired efflux gene.In addition,sample cluster analysis were performed.RESULTS Resistant genes to beta-lactams,aminoglycosides,quinolones were all positive in every strain.Furthermore,4 kinds of beta-lactam-resistance genes（blaTEM,blaADC,blaOXA-23 group,blaOXA-51group）,5kinds of aminoglycoside-resistance genes（armA,aac（3）-Ⅰ,aac（6′）-Ⅰb,ant（3″）-Ⅰ,aph3′-Ⅰ）were positive,mutations existed in all gyrA,and positive rates of adeB were high.Linkage detection of beta-lactamase gene and insertion sequence showed that positive rates of blaADC-ISaba1,blaOXA-23group-ISaba1,and blaOXA-51group-ISaba1 were 90.6%,100.0%,and 0.0%,respectively.Sample cluster analysis showed that strain No.6was a outer cluster,and other strains were in cluster A,and blaADC were mediated by ISaba1 in cluster A-1,while blaADC were not mediated by ISaba1 in cluster A-2.CONCLUSION Agrreegation in this group of pandrug-resistant A.baumannii and 5clones existed.So it is important to monitor and control nosocomial infection in time depending on phylogenetic analysis among strains.