Detection of T6SS secretory system and membrane purine involved in antibiotic resistance in multidrug-resistant Acinetobacter  baumannii isolates

Subject Areas : Microbial Biotechnology

Tohid Piri Gharaghie ¹ , Abbas Doosti ² , Seyed Abbas Mirzaei ³

1 - Department of Biology, Faculty of Basic Sciences, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran.
2 - Department of Biology, Biotechnology Research Center, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran. '
3 - Cellular and Molecular Research Center, Institute of Basic Health Sciences, Shahrekord University of Medical Sciences, Shahrekord, Iran

Received: 2020-10-14 Accepted : 2021-04-03 Published : 2021-05-22

Keywords: Acinetobacter baumannii, Resistance to carbapenems, T6SS secretory system, Membrane purine,

Abstract :

Background & Objectives: Type 6 secretory system (T6SS) and the presence of a strong efflux pump due to membrane purine are important indicators of pathogenicity of Acinetobacter baumannii. This study aimed to track the secretory system of T6SS and membrane purine as well as the pattern of antibiotic resistance in clinical isolates.Materials and methods: This cross-sectional descriptive study was performed on 33 strains of A. baumannii isolated from clinical samples including blood, urine, respiratory trachea, and wound. Antibiotic susceptibility of isolates was evaluated by the disk diffusion method according to CLSI protocol. Also, the frequency of genes encoding the effector proteins secreted from the type 6     secretory system and membrane purine was determined using Multiplex PCR.Results: 31 strains of A. baumannii were identified, using the molecular method.  A. baumannii isolates showed 93.55% sensitivity to colistin sulfate. The lowest susceptibility was related to five classes of antibiotics: fluoroquinolones (12.9%), cephalosporins (6.45%), aminoglycosides (6.45%), macrolides (16.1%), and inhibitory antibiotics (12.1%). The results showed that in addition to the MDR phenotype (100% of isolates), 20 isolates (64.52%) had the XDR phenotype. The frequency of the hcp gene was confirmed in 18 isolates (58%) and ompC in all isolates (100%). Also, the frequency of the ompC gene in MDR and XDR isolates was 100%. However, the hcp gene was observed only in the XDR phenotype with 90% frequency. Conclusion: The results of this study showed the possible effect of the hcp gene on the compatibility of A. baumannii isolates with unfavorable conditions and the occurrence of resistance phenotype.