Molecular Methods for Identification of Acinetobacter Species by Partial Sequencing of the rpoB and 16S rRNA Genes.

Khosravi, Azar dokht. and Sadeghi, Parisa. and Hashemi Shahraki, Abdolrazagh. and Heidarieh, Parvin. and Sheikhi, Nasrin. (2015) Molecular Methods for Identification of Acinetobacter Species by Partial Sequencing of the rpoB and 16S rRNA Genes. Journal of clinical and diagnostic research : JCDR, 9 (7). DC09-13. ISSN 2249-782X


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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. MATERIALS AND 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. CONCLUSION 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.

Item Type: Article
Uncontrolled Keywords: Nosocomial infections; PCR-RFLP; Phenotypic tests; Susceptibility testing
Subjects: WC Communicable Diseases
QU Biochemistry
Divisions: Reserach Vice-Chancellar Department > Cellular and Molecular Research Center
Depositing User: Users 1 not found.
Date Deposited: 25 Jul 2017 08:18
Last Modified: 20 May 2018 08:31

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