Gene expressing analysis indicates the role of Pyrogallol as a novel antibiofilm and antivirulence agent against Acinetobacter baumannii

AbstractMultidrug-resistant Acinetobacter baumannii infection has recently emerged as a worldwide clinical problem and colistin is increasingly being used as last resort therapy. Despite its favorable bacterial killing, resistance and heteroresistance to colistin have been described. Mutations in the PmrAB regulatory pathway have been already associated with colistin resistance whereas the mechanisms for heteroresistance remain largely unknown. The purpose of the present study is to investigate the role of PmrAB in laboratory-selected mutants representative of global epidemic strains. During brief colistin exposure, colistin resistant and colistin heteroresistant mutants were selected in a one-step strategy. Population Analysis Profiling (PAP) was performed to confirm the suspected phenotype. Upon withdrawal of selective pressure, compensatory mutations were evaluated in another one-step strategy. A trans-complementation assay was designed to delineate the involvement of the PmrAB regulatory system using qPCR and PAP. Mutations in the PmrAB regulatory pathway were associated with colistin resistance and colistin heteroresistance as well. The transcomplementation assay provides a proof for the role played by changes in the PmrAB regulatory pathway. The level of colistin resistance is correlated to the level of expression of pmrC. The resistance phenotype was partially restored since the complemented strain became heteroresistant. This report shows the role of different mutations in the PmrAB regulatory pathway and warns on the development of colistin heteroresistance that could be present but not easily detected with routine testing.

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Building resilience with aerobic exercise: role of FKBP5

Current Neuropharmacology ◽

10.2174/1570159x19666210408124937 ◽

2021 ◽

Vol 19 ◽

Author(s):

P. Sampedro-Piquero ◽

R.D. Moreno-Fernández

Keyword(s):

Aerobic Exercise ◽

Strong Inhibitor ◽

Fk506 Binding Protein ◽

Promising Target ◽

Important Regulator ◽

Anxiety Response ◽

Preclinical And Clinical Studies ◽

Gene Expressing ◽

Regular Practice

: Both preclinical and clinical studies have pointed that aerobic exercise, at moderate doses, is beneficial at all stages of life by promoting a range of physiological and neuroplastic adaptations that reduce the anxiety response. Previous research about this topic have repeatedly described how the regular practice of aerobic exercise induces a positive regulation of neuroplasticity and neurogenesis-related genes, as well as a better control of the HPA axis function. However, limited progress has been carried out in the integration of neuroendocrine and neuroplastic changes, as well as in introducing new factors to understand how aerobic exercise can promote resilience to future stressful conditions. Resilience is defined as the ability to adapt to stress while maintaining healthy mental and physical performance. Consistent findings point to an important role of FKBP5, the gene expressing FK506-binding protein 51 (FKBP51), as a strong inhibitor of the glucocorticoid receptor (GR), and thus, an important regulator of the stress response. We propose that aerobic exercise could contribute to modulate FKBP5 activity acting as a potential therapeutic approach for mood disorders. In this sense, aerobic exercise is well known for increasing the growth factor BDNF, which by downstream pathways could affect the FKBP5 activity. Therefore, our manuscript has the aim of analyzing how FKBP5 could constitute a promising target of aerobic exercise promoting resilient-related phenotypes.

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Biofilm Formation Caused by Clinical Acinetobacter baumannii Isolates Is Associated with Overexpression of the AdeFGH Efflux Pump

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00877-15 ◽

2015 ◽

Vol 59 (8) ◽

pp. 4817-4825 ◽

Cited By ~ 58

Author(s):

Xinlong He ◽

Feng Lu ◽

Fenglai Yuan ◽

Donglin Jiang ◽

Peng Zhao ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Gene Transcription ◽

Biofilm Formation ◽

Efflux Pump ◽

Outer Membrane Proteins ◽

Content Type ◽

Potential Association ◽

Genes Encoding ◽

Clinical Environments

ABSTRACTChronic wound infections are associated with biofilm formation, which in turn has been correlated with drug resistance. However, the mechanism by which bacteria form biofilms in clinical environments is not clearly understood. This study was designed to investigate the biofilm formation potency ofAcinetobacter baumanniiand the potential association of biofilm formation with genes encoding efflux pumps, quorum-sensing regulators, and outer membrane proteins. A total of 48 clinically isolatedA. baumanniistrains, identified by enterobacterial repetitive intergenic consensus (ERIC)-PCR as types A-II, A-III, and A-IV, were analyzed. Three representative strains, which were designatedA. baumanniiABR2, ABR11, and ABS17, were used to evaluate antimicrobial susceptibility, biofilm inducibility, and gene transcription (abaI,adeB,adeG,adeJ,carO, andompA). A significant increase in the MICs of different classes of antibiotics was observed in the biofilm cells. The formation of a biofilm was significantly induced in all the representative strains exposed to levofloxacin. The levels of gene transcription varied between bacterial genotypes, antibiotics, and antibiotic concentrations. The upregulation ofadeGcorrelated with biofilm induction. The consistent upregulation ofadeGandabaIwas detected in A-III-typeA. baumanniiin response to levofloxacin and meropenem (1/8 to 1/2× the MIC), conditions which resulted in the greatest extent of biofilm induction. This study demonstrates a potential role of the AdeFGH efflux pump in the synthesis and transport of autoinducer molecules during biofilm formation, suggesting a link between low-dose antimicrobial therapy and a high risk of biofilm infections caused byA. baumannii. This study provides useful information for the development of antibiofilm strategies.

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The Mutation of Conservative Asp268 Residue in the Peptidoglycan-Associated Domain of the OmpA Protein Affects Multiple Acinetobacter baumannii Virulence Characteristics

Molecules ◽

10.3390/molecules24101972 ◽

2019 ◽

Vol 24 (10) ◽

pp. 1972 ◽

Cited By ~ 2

Author(s):

Jūratė Skerniškytė ◽

Emilija Karazijaitė ◽

Julien Deschamps ◽

Renatas Krasauskas ◽

Romain Briandet ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Outer Membrane ◽

Protein A ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Clinical Strain ◽

Infection Model ◽

Terminal Domain ◽

Ompa Protein

Acinetobacter baumannii is a nosocomial human pathogen of increasing concern due to its multidrug resistance profile. The outer membrane protein A (OmpA) is an abundant bacterial cell surface component involved in A. baumannii pathogenesis. It has been shown that the C-terminal domain of OmpA is located in the periplasm and non-covalently associates with the peptidoglycan layer via two conserved amino acids, thereby anchoring OmpA to the cell wall. Here, we investigated the role of one of the respective residues, D268 in OmpA of A. baumannii clinical strain Ab169, on its virulence characteristics by complementing the ΔompA mutant with the plasmid-borne ompAD268A allele. We show that while restoring the impaired biofilm formation of the ΔompA strain, the Ab169ompAD268A mutant tended to form bacterial filaments, indicating the abnormalities in cell division. Moreover, the Ab169 OmpA D268-mediated association to peptidoglycan was required for the manifestation of twitching motility, desiccation resistance, serum-induced killing, adhesion to epithelial cells and virulence in a nematode infection model, although it was dispensable for the uptake of β-lactam antibiotics by outer membrane vesicles. Overall, the results of this study demonstrate that the OmpA C-terminal domain-mediated association to peptidoglycan is critical for a number of virulent properties displayed by A. baumannii outside and within the host.

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Characterization of RelA in Acinetobacter baumannii

Journal of Bacteriology ◽

10.1128/jb.00045-20 ◽

2020 ◽

Vol 202 (12) ◽

Cited By ~ 3

Author(s):

María Pérez-Varela ◽

Aimee R. P. Tierney ◽

Ju-Sim Kim ◽

Andrés Vázquez-Torres ◽

Philip Rather

Keyword(s):

Acinetobacter Baumannii ◽

Galleria Mellonella ◽

Multidrug Resistant ◽

Cell Physiology ◽

Content Type ◽

Content Model ◽

Transposon Insertion ◽

Downstream Effectors

ABSTRACT In response to nutrient depletion, the RelA and SpoT proteins generate the signaling molecule (p)ppGpp, which then controls a number of downstream effectors to modulate cell physiology. In Acinetobacter baumannii strain AB5075, a relA ortholog (ABUW_3302) was identified by a transposon insertion that conferred an unusual colony phenotype. An in-frame deletion in relA (ΔrelA) failed to produce detectable levels of ppGpp when amino acid starvation was induced with serine hydroxamate. The ΔrelA mutant was blocked from switching from the virulent opaque colony variant (VIR-O) to the avirulent translucent colony variant (AV-T), but the rate of AV-T to VIR-O switching was unchanged. In addition, the ΔrelA mutation resulted in a pronounced hypermotile phenotype on 0.35% agar plates. This hypermotility was dependent on the activation of a LysR regulator ABUW_1132, which was required for expression of AbaR, a LuxR family quorum-sensing regulator. In the ΔrelA mutant, ABUW_1132 was also required for the increased expression of an operon composed of the ABUW_3766-ABUW_3773 genes required for production of the surfactant-like lipopeptide acinetin 505. Additional phenotypes identified in the ΔrelA mutant included (i) cell elongation at high density, (ii) reduced formation of persister cells tolerant to colistin and rifampin, and (iii) decreased virulence in a Galleria mellonella model. IMPORTANCE Acinetobacter baumannii is a pathogen of worldwide importance. Due to the increasing prevalence of antibiotic resistance, these infections are becoming increasingly difficult to treat. New therapies are required to combat multidrug-resistant isolates. The role of RelA in A. baumannii is largely unknown. This study demonstrates that like in other bacteria, RelA controls a variety of functions, including virulence. Strategies to inhibit the activity of RelA and the resulting production of ppGpp could inhibit virulence and may represent a new therapeutic approach.

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The Role of the CopA Copper Efflux System in Acinetobacter baumannii Virulence

International Journal of Molecular Sciences ◽

10.3390/ijms20030575 ◽

2019 ◽

Vol 20 (3) ◽

pp. 575 ◽

Cited By ~ 11

Author(s):

Saleh Alquethamy ◽

Marjan Khorvash ◽

Victoria Pederick ◽

Jonathan Whittall ◽

James Paton ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Copper Toxicity ◽

In Silico Analysis ◽

Opportunistic Pathogen ◽

Copper Resistance ◽

Copper Stress ◽

Causative Agents ◽

High Level ◽

P Type

Acinetobacter baumannii has emerged as one of the leading causative agents of nosocomial infections. Due to its high level of intrinsic and adapted antibiotic resistance, treatment failure rates are high, which allows this opportunistic pathogen to thrive during infection in immune-compromised patients. A. baumannii can cause infections within a broad range of host niches, with pneumonia and bacteraemia being associated with the greatest levels of morbidity and mortality. Although its resistance to antibiotics is widely studied, our understanding of the mechanisms required for dealing with environmental stresses related to virulence and hospital persistence, such as copper toxicity, is limited. Here, we performed an in silico analysis of the A. baumannii copper resistome, examining its regulation under copper stress. Using comparative analyses of bacterial P-type ATPases, we propose that A. baumannii encodes a member of a novel subgroup of P1B-1 ATPases. Analyses of three putative inner membrane copper efflux systems identified the P1B-1 ATPase CopA as the primary mediator of cytoplasmic copper resistance in A. baumannii. Using a murine model of A. baumannii pneumonia, we reveal that CopA contributes to the virulence of A. baumannii. Collectively, this study advances our understanding of how A. baumannii deals with environmental copper toxicity, and it provides novel insights into how A. baumannii combats adversities encountered as part of the host immune defence.

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