scholarly journals Characteristics and Diversity of Mutations in Regulatory Genes of Resistance-nodulation-cell Division Efflux Pumps in Association With Drug-resistant Clinical Isolates of Acinetobacter Baumannii

2021 ◽  
Author(s):  
Bahare Salehi ◽  
Zohreh Ghalavand ◽  
Abbas Yadegar ◽  
Gita Eslami
Keyword(s):  
Cell Division ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Regulatory Genes ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Rnd Efflux Pumps ◽  
Multiple Antibiotics

Abstract Background: This study was aimed to characterize the genetic diversity and expression of three putative resistance-nodulation-cell division (RND)-type efflux systems and their contribution to multidrug efflux in clinical isolates of Acinetobacter baumannii.Methods: Antimicrobial susceptibility testing of 95 A. baumannii isolates was determined by Kirby-Bauer disk diffusion for 18 antibiotics and minimum inhibitory concentration (MIC) of colistin was determined by the broth microdilution method. Moreover, the MIC of five classes of antibiotics was assessed using E-test strips in the presence and absence of phenylalanine-arginine beta-naphthylamide (PAβN). Regulatory genes of the RND efflux pumps (adeRS, adeL, adeN and baeSR) were subjected to sequencing. The relative expression of adeB, adeG and adeJ genes was determined by quantitative real-time PCR (RT-PCR).Results: Overall, the majority of isolates (93%) were extensively drug-resistant (XDR). In the phenotypic assay, efflux pump activity was observed in 40% of the isolates against multiple antibiotics mainly tigecycline. However, we found no efflux activity against imipenem. Several amino acid substitutions were detected in the products of regulatory genes; except in AdeN. Of note, G186V mutation in AdeS was found to be associated with overexpression of its efflux pump. No insertion sequences were detected. Conclusions: Our findings outlined the role of RND efflux pumps in resistance of A. baumannii to multiple antibiotics particularly tigecycline, and pointed out the importance of a variety of single mutations in the corresponding regulatory systems. Further studies are required to decipher the precise role of RND efflux pumps in multidrug-resistant clinical isolates of A. baumannii.

scholarly journals Characteristics and diversity of mutations in regulatory genes of resistance-nodulation-cell division efflux pumps in association with drug-resistant clinical isolates of Acinetobacter baumannii

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Bahare Salehi ◽  
Zohreh Ghalavand ◽  
Abbas Yadegar ◽  
Gita Eslami
Keyword(s):  
Cell Division ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Regulatory Genes ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Rnd Efflux Pumps ◽  
Multiple Antibiotics

Abstract Background This study was aimed to characterize the genetic diversity and expression of three putative resistance-nodulation-cell division (RND)-type efflux systems and their contribution to multidrug efflux in clinical isolates of Acinetobacter baumannii. Methods Antimicrobial susceptibility testing of 95 A. baumannii isolates was determined by Kirby-Bauer disk diffusion for 18 antibiotics and minimum inhibitory concentration (MIC) of colistin was determined by the broth microdilution method. Moreover, the MIC of five classes of antibiotics was assessed using E-test strips in the presence and absence of phenylalanine-arginine beta-naphthylamide (PAβN). Regulatory genes of the RND efflux pumps (adeRS, adeL, adeN and baeSR) were subjected to sequencing. The relative expression of adeB, adeG and adeJ genes was determined by quantitative real-time PCR (qRT-PCR). Results Overall, the majority of isolates (94%) were extensively drug-resistant (XDR). In the phenotypic assay, efflux pump activity was observed in 40% of the isolates against multiple antibiotics mainly tigecycline. However, we found no efflux activity against imipenem. Several amino acid substitutions were detected in the products of regulatory genes; except in AdeN. Of note, G186V mutation in AdeS was found to be associated with overexpression of its efflux pump. No insertion sequences were detected. Conclusions Our findings outlined the role of RND efflux pumps in resistance of A. baumannii to multiple antibiotics particularly tigecycline, and pointed out the importance of a variety of single mutations in the corresponding regulatory systems. Further studies are required to decipher the precise role of RND efflux pumps in multidrug-resistant clinical isolates of A. baumannii.

scholarly journals Characteristics and diversity of mutations in regulatory genes of resistance-nodulation-cell division efflux pumps in association with drug-resistant clinical isolates of Acinetobacter baumannii

2020 ◽  
Author(s):  
Bahare Salehi ◽  
Zohreh Ghalavand ◽  
Abbas Yadegar ◽  
Gita Eslami
Keyword(s):  
Cell Division ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Regulatory Genes ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Broth Microdilution Method ◽  
Rnd Efflux Pumps ◽  
Multiple Antibiotics

Abstract Background: This study aimed to characterize the regulation and expression of three putative resistance-nodulation-cell division (RND)-type efflux systems and their contribution to multidrug efflux in clinical isolates of Acinetobacter baumannii. Methods: Antimicrobial susceptibility testing (AST) of 95 A. baumannii isolates was determined by Kirby-Bauer disk diffusion for 18 antibiotics and minimum inhibitory concentration (MIC) of colistin was determined by broth microdilution method. Moreover, MIC of five classes of antibiotics was assessed using E-test strips in the presence and absence of phenylalanine-arginine beta-naphthylamide (PAβN). Regulatory genes of RND efflux pumps (AdeRS, AdeL, AdeN and BaeSR) were subjected to sequencing. The relative expression of adeB. adeG and adeJ genes was determined by quantitative real-time PCR (RT-PCR).Results: Overall, majority of isolates (93%) were extensively drug-resistant (XDR). In the phenotypic assay, efflux pump activity was observed in 40% of isolates against multiple antibiotics mainly tigecycline, but not to imipenem. Several amino acid substitutions were detected in the regulatory genes; except in AdeN. Of note, G186V in AdeS were found to be associated with overexpression of their relative efflux pumps. No insertion sequences (ISs) were detected. Conclusions: Our findings outline the role of RND efflux pumps in resistance of A. baumannii against multiple antibiotics particularly tigecycline, and point out importance of a variety of single mutations in the corresponding regulatory systems. Even though it has been concluded that multidrug resistance occurs as a result of a complex sets of different resistant mechanisms.

scholarly journals Characteristics and diversity of mutations in regulatory genes of resistance-nodulation-cell division efflux pumps in association with drug-resistant clinical isolates of Acinetobacter baumannii

2020 ◽  
Author(s):  
Bahare Salehi ◽  
Zohreh Ghalavand ◽  
Abbas Yadegar ◽  
Gita Eslami
Keyword(s):  
Cell Division ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Regulatory Genes ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Broth Microdilution Method ◽  
Rnd Efflux Pumps ◽  
Multiple Antibiotics

Abstract Background: This study aimed to characterize the regulation and expression of three putative resistance-nodulation-cell division (RND)-type efflux systems and their contribution to multidrug efflux in clinical isolates of Acinetobacter baumannii.Methods: Antimicrobial susceptibility testing (AST) of 95 A. baumannii isolates was determined by Kirby-Bauer disk diffusion for 18 antibiotics and minimum inhibitory concentration (MIC) of colistin was determined by broth microdilution method. Moreover, MIC of five classes of antibiotics was assessed using E-test strips in the presence and absence of phenylalanine-arginine beta-naphthylamide (PAβN). Regulatory genes of RND efflux pumps (AdeRS, AdeL, AdeN and BaeSR) were subjected to sequencing. The relative expression of adeB. adeG and adeJ genes was determined by quantitative real-time PCR (RT-PCR).Results: Overall, majority of isolates (93%) were extensively drug-resistant (XDR). In the phenotypic assay, efflux pump activity was observed in 40% of isolates against multiple antibiotics mainly tigecycline, but not to imipenem. Several amino acid substitutions were detected in the regulatory genes; except in AdeN. Of note, G186V in AdeS were found to be associated with overexpression of their relative efflux pumps. No insertion sequences (ISs) were detected.Conclusions: Our findings outline the role of RND efflux pumps in resistance of A. baumannii against multiple antibiotics particularly tigecycline, and point out importance of a variety of single mutations in the corresponding regulatory systems. Even though it has been concluded that multidrug resistance occurs as a result of a complex sets of different resistant mechanisms.

scholarly journals Characteristics and diversity of mutations in regulatory genes of resistance-nodulation-cell division efflux pumps in association with drug-resistant clinical isolates of Acinetobacter baumannii

2020 ◽  
Author(s):  
Bahare Salehi ◽  
Zohreh Ghalavand ◽  
Abbas Yadegar ◽  
Gita Eslami
Keyword(s):  
Cell Division ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Regulatory Genes ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Broth Microdilution Method ◽  
Rnd Efflux Pumps ◽  
Multiple Antibiotics

Abstract Background This study aimed to characterize the regulation and expression of three putative resistance-nodulation-cell division (RND)-type efflux systems and their contribution to multidrug efflux in clinical isolates of Acinetobacter baumannii. Methods Antimicrobial susceptibility testing (AST) of 95 A. baumannii isolates was determined by Kirby-Bauer disk diffusion for 18 antibiotics and minimum inhibitory concentration (MIC) of colistin was determined by broth microdilution method. Moreover, MIC of five classes of antibiotics was assessed using E-test strips in the presence and absence of phenylalanine-arginine beta-naphthylamide (PAβN). Regulatory genes of RND efflux pumps (AdeRS, AdeL, AdeN and BaeSR) were subjected to sequencing. The relative expression of adeB. adeG and adeJ genes was determined by quantitative real-time PCR (RT-PCR). Results Overall, majority of isolates (93%) were extensively drug-resistant (XDR). In the phenotypic assay, efflux pump activity was observed in 40% of isolates against multiple antibiotics mainly tigecycline, but not to imipenem. Several amino acid substitutions were detected in the regulatory genes; except in AdeN. Of note, A136V in AdeR and G186V in AdeS were found to be associated with overexpression of their relative efflux pumps. No insertion sequences (ISs) were detected. Conclusions Our findings outline the role of RND efflux pumps in resistance of A. baumannii against multiple antibiotics particularly tigecycline, and point out importance of a variety of single mutations in the corresponding regulatory systems. Even though it has been concluded that multidrug resistance occurs as a result of a complex sets of different resistant mechanisms.

scholarly journals Characteristics and diversity of mutations in regulatory genes of resistance-nodulation-cell division efflux pumps in association with drug-resistant clinical isolates of Acinetobacter baumannii

2020 ◽  
Author(s):  
Bahare Salehi ◽  
Zohreh Ghalavand ◽  
Abbas Yadegar ◽  
Gita Eslami
Keyword(s):  
Cell Division ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Regulatory Genes ◽  
Clinical Isolates ◽  
Drug Resistant ◽  
Broth Microdilution Method ◽  
Rnd Efflux Pumps ◽  
Multiple Antibiotics

Abstract Background: This study aimed to characterize the regulation and expression of three putative resistance-nodulation-cell division (RND)-type efflux systems and their contribution to multidrug efflux in clinical isolates of Acinetobacter baumannii. Methods: Antimicrobial susceptibility testing (AST) of 95 A. baumannii isolates was determined by Kirby-Bauer disk diffusion for 18 antibiotics and minimum inhibitory concentration (MIC) of colistin was determined by broth microdilution method. Moreover, MIC of five classes of antibiotics was assessed using E-test strips in the presence and absence of phenylalanine-arginine beta-naphthylamide (PAβN). Regulatory genes of RND efflux pumps (AdeRS, AdeL, AdeN and BaeSR) were subjected to sequencing. The relative expression of adeB. adeG and adeJ genes was determined by quantitative real-time PCR (RT-PCR).Results: Overall, majority of isolates (93%) were extensively drug-resistant (XDR). In the phenotypic assay, efflux pump activity was observed in 40% of isolates against multiple antibiotics mainly tigecycline, but not to imipenem. Several amino acid substitutions were detected in the regulatory genes; except in AdeN. Of note, A136V in AdeR and G186V in AdeS were found to be associated with overexpression of their relative efflux pumps. No insertion sequences (ISs) were detected. Conclusions: Our findings outline the role of RND efflux pumps in resistance of A. baumannii against multiple antibiotics particularly tigecycline, and point out importance of a variety of single mutations in the corresponding regulatory systems. Even though it has been concluded that multidrug resistance occurs as a result of a complex sets of different resistant mechanisms

scholarly journals Diversity of mutations in regulatory genes of resistance-nodulation-cell division efflux pumps in association with tigecycline resistance in Acinetobacter baumannii

2018 ◽  
Vol 73 (6) ◽  
pp. 1501-1508 ◽  
Author(s):  
Stefanie Gerson ◽  
Jennifer Nowak ◽  
Esther Zander ◽  
Julia Ertel ◽  
Yurong Wen ◽  
...  
Keyword(s):  
Cell Division ◽  
Acinetobacter Baumannii ◽  
Efflux Pumps ◽  
Regulatory Genes

scholarly journals In-silico interaction studies on the efflux pumps suggest polymyxins to be better substrate for RND efflux pumps in multi-drug resistant strains of Acinetobacter baumannii

2017 ◽  
Author(s):  
Privita Verma ◽  
Vishvanath Tiwari
Keyword(s):  
Free Energy ◽  
Multidrug Resistance ◽  
In Silico ◽  
Efflux Pump ◽  
Binding Free Energy ◽  
Efflux Pumps ◽  
Drug Resistant ◽  
Rnd Efflux Pumps ◽  
Resistant Strains ◽  
Drug Resistant Strains

Bacterial efflux pumps have emerged as antibiotic resistance determinants and confers multidrug resistance to a broad range of antimicrobials as well as non-antibiotic substances by potentially extruding them out. These are also associated with the virulence and biofilm formation. Thus, development of inhibitors against these effective antibacterial targets can be a highly beneficial approach in order to reverse the multidrug resistance (MDR) in the clinical relevant strains. A keen study on the efflux of foregoing or commonly used antibiotics will contribute in finding substrates that could bind efficiently with these efflux pumps. In the present study, we have explored efflux pumps belonging to Resistance-Nodulation-Division (RND) family as they are found prevalent in gram negative pathogens such as A. baumannii. The two RND efflux pumps under consideration are AdeABC and AcrAB-TolC. For comparative analysis, a non-RND family efflux pump i.e. NorM is selected here. We employed a series of computational techniques ranging from molecular docking to binding free energy estimation and molecular dynamics simulations to determine the binding affinity for different classess of drugs namely aminoglycosides, polymyxins, β-lactams, tetracyclines, glycylcyclines, quinolones and metronidazole against the efflux pumps under study. Our results revealed that class polymyxins has the highest binding affinity with the RND efflux pumps i.e. AcrAB-TolC and AdeABC as well as non-RND efflux pump (NorM). The experimental data was found to much extent in accordance with the binding free energy scores obtained from our in silico analysis. To recapitulate the outcome, polymyxins can possibly be the most efficient substrate for both RND and non-RND efflux pumps, thus, can be used as a reference drug for designing potent efflux pump inhibitors against multi-drug resistant strains.

Colistin Induced Assortment of Antimicrobial Resistance in a Clinical Isolate of Acinetobacter baumannii SD01

2020 ◽  
Vol 20 (4) ◽  
pp. 501-505
Author(s):  
Debarati Paul ◽  
Swarupa Mallick ◽  
Swati Das ◽  
Suman Saha ◽  
Ananta K. Ghosh ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Genetic System ◽  
Opportunistic Pathogen ◽  
Efflux Pumps ◽  
Integral Role ◽  
Antimicrobial Susceptibility Tests ◽  
Cyclic Polypeptide ◽  
Susceptibility Tests

Background: Colistin was considered as the most effective antibiotic against Acinetobacter baumannii, a widely-known opportunistic pathogen. In recent years, a number of colistin resistant strains have also been reported. Objective: This work is commenced to investigate the contribution of efflux pumps toward resistance to colistin-like cyclic polypeptide antibiotics, since the efflux pumps serve as the escape routes leading to drug-resistance. Methods: RNA was extracted from A. baumannii isolates cultured from samples procured by tracheal aspiration of infected patients. The expressions of gene(s) that played major roles in the regulation of efflux pump families and involvement of integron systems were studied using real time PCR. Antimicrobial susceptibility tests were conducted to investigate antibiotic resistance of the isolates. Results: It was observed that genes coding for sugE, ydhE, ydgE, mdfA, ynfA and tolC significantly contributed to resistance against colistin antibiotics, however, no significant transcriptional change was observed in the efflux pump, MexAB-OprM. Results suggest that A. baumanii readily pumps out colistin via efflux pumps belonging to MATE and SMR family. Conclusion: Integral role of efflux pumps and integron 1 genetic system was elucidated towards evolution of multi-drug resistant strain(s). Therefore, for accurate therapeutics, an early detection of efflux genes is crucial before prescribing against colistin resistant A. baumanii.

scholarly journals Screening antibiotics using an Hoechst 33342 dye-accumulation assay to detect efflux activity in Acinetobacter baumannii clinical isolates

2018 ◽  
Vol 11 (4) ◽  
pp. 371-378 ◽  
Author(s):  
In-Sun Choi ◽  
Choon-Mee Kim ◽  
Sook-Jin Jang
Keyword(s):  
Multidrug Resistance ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Multidrug Resistant ◽  
Clinical Isolates ◽  
Drug Efflux ◽  
Hoechst 33342 ◽  
Efflux Pump Inhibitor ◽  
Significant Difference

AbstractBackgroundUnderstanding the contribution of efflux pumps to the resistance of antibiotics is useful when considering strategies for antimicrobial therapy.ObjectivesTo assess the role of efflux activity on the resistance of antibiotics commonly used in hospitals.MethodsWe analyzed the efflux activity of 120 clinical isolates of Acinetobacter baumannii using an Hoechst 33342 (H33342) dye-accumulation assay. We compared the indicators for efflux activity of susceptible and non-susceptible groups of each of 16 tested antibiotics. To determine the role of efflux activity on resistance to an antibiotic, we used 3 criteria based on the results of the H33342-accumulation assay.ResultsThe evaluation suggests that efflux activity contributed to resistance to the following 11 antibiotics: cefepime, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, imipenem, meropenem, piperacillin, piperacillin/tazobactam, ticarcillin/ clavulanic acid, and tigecycline. However, ampicillin/sulbactam, minocycline, and trimethoprim/sulfamethoxazole did not meet the criteria, suggesting resistance may not be mediated by efflux activity. A significant difference in efflux activity was observed between bacteria belonging to the multidrug-resistant Acinetobacter baumannii (MDRAB) group and those belonging to the non-MDRAB group.ConclusionsEfflux activity may contribute to multidrug resistance and particularly resistance to numerous antibiotics used in hospitals. These antibiotics would be good candidates for combination therapeutic regimens consisting of an antibiotic and an efflux pump inhibitor as an adjuvant to combat drug efflux.

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