Biofilm formation in Acinetobacter baumannii was inhibited by PAβN while it had no association with antibiotic resistance

Abstract

This study was conducted to investigate the relationship between Acinetobacter baumannii biofilm formation and antibiotic resistance. Furthermore, the effects of PAβN, a potential efflux pump inhibitor, on A. baumannii biofilm formation and dispersion were tested, and the gene expression levels of efflux pumps were determined to study the mechanisms. A total of 92 A. baumannii isolates from infected patients were collected and identified by multiplex PCR. The antimicrobial susceptibility of A. baumannii clinical isolates was tested by VITEK 2 COMPACT®. Genotypes were determined by ERIC‐2 PCR. Biofilm formation and dispersion were detected by crystal violet staining. The presence and mRNA expression of efflux pump genes were analyzed by conventional PCR and real‐time PCR, respectively. More than 50% of the A. baumannii strains formed biofilm and were divided into different groups according to their biofilm‐forming ability. Antibiotic resistance rates among most groups did not significantly differ. There were 7 clonal groups in 92 strains of A. baumannii and no dominant clones among the different biofilm‐forming groups. PAβN inhibited A. baumannii biofilm formation and enhanced its dispersion, whereas adeB, adeJ, and adeG and the mRNA expression of adeB, abeM, and amvA showed no differences in the different biofilm‐forming groups. In conclusion, there was no clear relationship between biofilm formation and antibiotic resistance in A. baumannii. The effects of PAβN on A. baumannii biofilm formation and dispersion were independent of the efflux pumps.

Multidrug Resistant Acinetobacter baumannii Biofilms: Evaluation of Phenotypic–Genotypic Association and Susceptibility to Cinnamic and Gallic Acids

“…Similar correlations between IPM and LVX were recently described (El-Din et al, 2021), this may be attributed to the various impacts that resulted from a mutation at one or a few genetic loci (Adamus-Bialek et al, 2013). Our isolates exhibited much higher frequency (100%) of biofilm production as opposed to A. baumannii clinical isolates (70.1%) lately investigated from Egypt (Asaad et al, 2021), Iran (70.6%) (Ranjbar and Farahani, 2019), and China (54%) (Chen et al, 2020). Several studies linked high frequency of biofilm formation in A. baumannii with extended survival and resistance to external stresses such as limited nutrients and dehydration (Badave and Kulkarni, 2015;Sung, 2018).…”

Factors mediating Acinetobacter baumannii biofilm formation: Opportunities for developing therapeutics

“…In a clinical A. baumannii isolate, AdeFGH efflux pump was overexpressed along with abaI in sessile condition, suggesting its role in the efflux of substrates required for biofilm formation ( He et al., 2015 ). Targeting RND efflux pump with its inhibitor Phenylalanine-arginine beta-naphthylamide (PaβN) significantly reduced the biofilm formation ability of A. baumannii and weakly eradicated preformed biofilm ( Chen et al., 2020 ).…”

OmpA and Bap Genes as Virulence Genes Involved in Biofilm Formation of Acinetobacter baumannii

“…[15], Ranjbar and Farahani, [16], and Chen et al [17], who found that 76.9%, 70.6% and 54% of clinical A. baumannii isolates produced biofilms respectively.…”