The RND Efflux Pump Gene Expression in the Biofilm Formation of Acinetobacter baumannii

Ola A Abd El-Rahman; Fatma Rasslan; Safaa S Hassan; Hossam M Ashour; Reham Wasfi

doi:10.3390/antibiotics12020419

The RND Efflux Pump Gene Expression in the Biofilm Formation of Acinetobacter baumannii

Antibiotics (Basel). 2023 Feb 20;12(2):419. doi: 10.3390/antibiotics12020419.

Authors

Ola A Abd El-Rahman¹, Fatma Rasslan¹, Safaa S Hassan², Hossam M Ashour³, Reham Wasfi⁴

Affiliations

¹ Department of Microbiology and Immunology, Faculty of Pharmacy (Girls), Al-Azhar University, Cairo 11751, Egypt.
² Department of Clinical Pathology, National Cancer Institute, Cairo University, Cairo 11796, Egypt.
³ Department of Integrative Biology, College of Arts and Sciences, University of South Florida, St. Petersburg, FL 33701, USA.
⁴ Department of Microbiology and Immunology, Faculty of Pharmacy, October University for Modern Sciences and Arts (MSA), Giza 12451, Egypt.

Abstract

Multidrug resistant (MDR) Acinetobacter baumannii is a critical opportunistic pathogen in healthcare-associated infections (HAI). This is attributed to several factors, including its ability to develop biofilms that can enhance antimicrobial resistance (AMR) in addition to creating an environment for horizontal transfer of antibiotic resistance genes. The role of the efflux pump in biofilm formation is important for studies on alternative treatments for biofilms. One of the significant efflux pump families is the RND efflux pump family, which is common in Gram negative bacteria. The aim is to study the role of the RND efflux pump in biofilm formation by A. baumannii. The biofilm formation potential of thirty-four MDR A. baumannii isolates was evaluated by crystal violet assays. The effect of efflux pump inhibition and activation was studied using the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP) and the RND efflux pump substrate levofloxacin (at sub-MIC), respectively. The isolates were genotypically grouped by enterobacterial repetitive intergenic consensus (ERIC) typing and the expression of adeABC, adeFGH, and adeIJK efflux pump genes was measured by qPCR. Overall, 88.2% (30/34) of isolates were biofilm producers (the phenotype was variable including strong and weak producers). Efflux pump inhibition by CCCP reduced the biofilm formation significantly (p < 0.05) in 17.6% (6/34) of some isolates, whereas sub-MICs of the substrate levofloxacin increased biofilm formation in 20.5% (7/34) of other isolates. Overexpression of the three RND efflux pump genes was detected in five out of eleven selected isolates for qPCR with remarkable overexpression in the adeJ gene. No correlation was detected between the biofilm phenotype pattern and the RND efflux pump gene expression in biofilm cells relative to planktonic cells. In conclusion, the role of the RND efflux pumps AdeABC, AdeFGH, and AdeIJK in biofilm formation does not appear to be pivotal and the expression differs according to the genetic background of each strain. Thus, these pumps may not be a promising target for biofilm inhibition.

Keywords: Acinetobacter baumannii; AdeABC; AdeFGH; AdeIJK; RND efflux pump; biofilm.

Grants and funding

This research received no external funding.