Contribution of the AbaI/AbaR Quorum Sensing System to Resistance and Virulence of Acinetobacter baumannii Clinical Strains

Jie Tang; Yan Chen; Xinlei Wang; Yue Ding; Xiaoyu Sun; Zhaohui Ni

doi:10.2147/IDR.S276970

Contribution of the AbaI/AbaR Quorum Sensing System to Resistance and Virulence of Acinetobacter baumannii Clinical Strains

Infect Drug Resist. 2020 Nov 24:13:4273-4281. doi: 10.2147/IDR.S276970. eCollection 2020.

Authors

Jie Tang^#¹, Yan Chen^#², Xinlei Wang³, Yue Ding¹, Xiaoyu Sun¹, Zhaohui Ni¹

Affiliations

¹ Department of Pathogen Biology, The Key Laboratory of Zoonosis, Chinese Ministry of Education, College of Basic Medical Sciences, Jilin University, Changchun, Jilin 130021, People's Republic of China.
² Department of Neurosurgery, The Second Hospital of Jilin University, Changchun, China 130041, People's Republic of China.
³ Department of Clinical Laboratory, The Second Hospital of Jilin University, Changchun 130041, People's Republic of China.

^# Contributed equally.

Abstract

Background: Acinetobacter baumannii (A. baumannii) is one of the most important pathogens that cause serious nosocomial infections worldwide. However, there are few reports on the virulence of A. baumannii clinical isolates, and little is known about the mechanism regulating virulence and drug resistance. The aim of this study was to determine the prevalence of drug resistance and virulence profiles and explore features related to quorum sensing (QS).

Methods: A total of 80 clinical A. baumannii isolates were collected from Jilin province of China from 2012 to 2017. We investigated these clinical isolates with respect to biofilm formation, surface motility, adherence, invasion into A549 human alveolar epithelial cells, and virulence to Galleria mellonella. We also explored the prevalence of the AbaI/AbaR QS system and its correlation with bacterial virulence and drug resistance.

Results: The resistance rates of the isolates to 17 commonly used antibiotics were higher than 50%, and 75% of the isolates were multi-drug resistant. Approximately 95% (76/80) of the isolates showed the ability to form biofilms, of which 38 showed strong biofilm formation ability (+++). Only 5 strains showed strong surface-related motility. A high level of variability was found in adherence and invasion into A549 epithelial cells, and 16 isolates showed strong virulence to Galleria mellonella (none survived after 6 days of infection). Of the 61 isolates carrying abaI and abaR genes, 24 were found to produce N-acyl homoserine lactones (AHLs) detectable by biosensor bacteria. Correlation analysis revealed that abaI and abaR genes positively correlated with bacterial resistance rates. All strains showing obvious surface-related motility carried abaI and abaR genes and produced AHLs. The isolates with detectable QS systems also showed stronger invasiveness into A549 cells and pathogenicity toward G. mellonella than the QS-deficient isolates.

Conclusion: Our study demonstrates that the AbaI/AbaR QS system was widely distributed among the A. baumannii clinical isolates, was necessary for surface-related motility, and significantly correlated with drug resistance, invasion into epithelial cells, and virulence to G. mellonella.

Keywords: Acinetobacter baumannii; drug resistance; quorum sensing; virulence.

Grants and funding

This study was partially supported by grants from the National Natural Science Foundation of China (81601817), the Education Department of Jilin Province (JJKH20170820KJ), Jilin Province Science and Technology Department (20200201510JC) and grants from Department of Finance of Jilin Province(SWKYZ002).