title: Molecular Methods for Identification of Acinetobacter Species by Partial Sequencing of the rpoB and 16S rRNA Genes.
abstract: BACKGROUND
  Acinetobacter spp. is a diverse group of Gram-negative bacteria which are ubiquitous in soil and water, and an important cause of nosocomial infections. The purpose of this study was to identify a collection of Acinetobacter spp. clinical isolates accurately and to investigate their antibiotic susceptibility patterns.
  
  
  METHODS
  A total of 197 non-duplicate clinical isolates of Acinetobacter spp. isolates identified using conventional biochemical tests. The molecular technique of PCR-RFLP and sequence analysis of rpoB and 16S rRNA genes was applied for species identification. Antimicrobial susceptibility test was performed with a disk diffusion assay.
  
  
  RESULTS
  Based on 16S rRNA and rpoB genes analysis separately, most of clinical isolates can be identified with high bootstrap values. However, the identity of the isolate 555T was uncertain due to high similarity of A. grimontii and A. junii. Identification by concatenation of 16S rRNA and rpoB confirmed the identity of clinical isolates of Acenitobacer to species level confidently. Accordingly, the isolate 555T assigned as A. grimontii due to 100% similarity to A. grimontii. Moreover, this isolate showed 98.64% to A. junii. Besides, the identity of the isolates 218T and 364T was confirmed as Genomic species 3 and A. calcoaceticus respectively. So, the majority of Acinetobacter spp. isolates, were identified as: A. baumannii (131 isolates, 66%), A. calcoaceticus (9 isolates, 4.5%), and A. genomosp 16 (8 isolates, 4%). The rest of identified species showed the lower frequencies. In susceptibility test, 105 isolates (53%), presented high antibiotic resistance of 90% to ceftriaxone, piperacillin, piperacillin tazobactam, amikacin, and 81% to ciprofloxacin.
  
  
  CONCLUSIONS
  Sequence analysis of the 16S rRNA and rpoB spacer simultaneously was able to do identification of Acinetobacter spp. to species level. A.baumannii was identified as the most prevalent species with high antibiotic resistance. Other species showed lower frequencies ranged from 4 to 9 strains.
authors.affiliation: Professor, Department of Microbiology & Health Research Institute, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences , Ahvaz, Iran .
authors.forename: Azar Dokht
authors.initials: AD
authors.lastname: Khosravi
authors.affiliation: Research Assistant, Department of Microbiology, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences , Ahvaz, Iran; Clinical Biochemistry Research Center, Shahrekord University of Medical Sciences, Shahrekord, Iran .
authors.forename: Parisa
authors.initials: P
authors.lastname: Sadeghi
authors.affiliation: Assistant Professor, Department of Health Research Institute, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences , Ahvaz, Iran; Department of Epidemiology, Pasteur Institute of Iran .
authors.forename: Abdolrazagh Hashemi
authors.initials: AH
authors.lastname: Shahraki
authors.affiliation: Assistant Professor, Department of Bacteriology and Virology, Alborz University of Medical Sciences , Karaj, Iran .
authors.forename: Parvin
authors.initials: P
authors.lastname: Heidarieh
authors.affiliation: Research Assistant, Department of Microbiology Unit, Masoud Medical Laboratory , Tehran, Iran .
authors.forename: Nasrin
authors.initials: N
authors.lastname: Sheikhi
keywords: Nosocomial infections; PCR-RFLP; Phenotypic tests; Susceptibility testing