Whole Genome Sequencing Of A Multidrug Resistant Acinetobacter Baumannii Isolate And A Systematical Bioinformatics Study

Acinetobacter baumannii is identified as an aerobic, nonfermentative, nonmotilegram-negative bacillus. As an important opportunistic pathogen, A.baumannii isresponsible for severe nosocomial infections including pneumonia, meningitis,urinary tract and blood-stream infections. A.baumannii is becoming an increasingthreat to for its ability to develop multi-drug resistance (MDR), which makes itdifficult to treat and often leads to high mortality. Insights into the drug resistancemechanisms and epidemiology of Acinetobacter baumannii should provide theoreticalguidance to the proper use of antibiotics clinically. High-throughput pyrosequencinghas become a cost-effective approach to determine the whole genome sequence andreveal the drug resistance mechanisms of A.baumannii.In this study, Acinetobacter baumannii strain MDR-TJ, which was resistant topenicillins, cephalosporins, aminoglycosides, quinolones, and also imipenem, wasisolated at the Second Hospital of Tianjin Medical University. The whole genomesequence of strain MDR-TJ was determined by using Roche454GS FLX Titanium.The genome of MDR-TJ consists of a circular chromosome of3,964,912bp and twoplasmids of77,528bp and110,967bp, respectively. The chromosome with GC contentof39.1%encoded3,827genes. Plasmid pABTJ1carried109coding genes and thecarbapenem-resistance gene blaOXA-23carried by transposon Tn2009is located on aconjugative plasmid pABTJ1. Plasmid pABTJ2contained many phage proteins and atRNA gene. Strain MDR-TJ belongs to European clone II according to multiple locussequence typing (MLST). The comM gene of MDR-TJ was interrupted by a resistanceisland designated AbaR25. AbaR25is mainly composed of two copies of Tn6022andcontains resistance genes of tetracycline, streptomycin and sulfonamide. The structureof AbaR25differs substantially from the resistance islands found in European clone Iisolates. Through the analysis of seven currently-available resistance islands identifiedin European clone II isolates, we found that the comM genes of European clone IIisolates were frequently interrupted by transposon Tn6022.