scholarly journals Acinetobacter baumannii Increases Tolerance to Antibiotics in Response to Monovalent Cations

2009 ◽  
Vol 54 (3) ◽  
pp. 1029-1041 ◽  
Author(s):  
M. Indriati Hood ◽  
Anna C. Jacobs ◽  
Khalid Sayood ◽  
Paul M. Dunman ◽  
Eric P. Skaar
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Outer Membrane Proteins ◽  
Hospital Setting ◽  
Transcriptional Response ◽  
Hospital Environment ◽  
Transcriptional Level ◽  
Efflux Pump Inhibitor ◽  
Regulatory Cascade

ABSTRACT Acinetobacter baumannii is well adapted to the hospital environment, where infections caused by this organism are associated with significant morbidity and mortality. Genetic determinants of antimicrobial resistance have been described extensively, yet the mechanisms by which A. baumannii regulates antibiotic resistance have not been defined. We sought to identify signals encountered within the hospital setting or human host that alter the resistance phenotype of A. baumannii. In this regard, we have identified NaCl as being an important signal that induces significant tolerance to aminoglycosides, carbapenems, quinolones, and colistin upon the culturing of A. baumannii cells in physiological NaCl concentrations. Proteomic analyses of A. baumannii culture supernatants revealed the release of outer membrane proteins in high NaCl, including two porins (CarO and a 33- to 36-kDa protein) whose loss or inactivation is associated with antibiotic resistance. To determine if NaCl affected expression at the transcriptional level, the transcriptional response to NaCl was determined by microarray analyses. These analyses highlighted 18 genes encoding putative efflux transporters that are significantly upregulated in response to NaCl. Consistent with this, the effect of NaCl on the tolerance to levofloxacin and amikacin was significantly reduced upon the treatment of A. baumannii with an efflux pump inhibitor. The effect of physiological concentrations of NaCl on colistin resistance was conserved in a panel of multidrug-resistant isolates of A. baumannii, underscoring the clinical significance of these observations. Taken together, these data demonstrate that A. baumannii sets in motion a global regulatory cascade in response to physiological NaCl concentrations, resulting in broad-spectrum tolerance to antibiotics.

scholarly journals Association of Efflux Pump and OMPs with Antibiotic Susceptibility Among ESBL-Producing Klebsiella Pneumoniae Clinical Strains in Malaysia

2021 ◽  
Author(s):  
Golnaz Mobasseri ◽  
Thong Kwai Lin ◽  
Cindy Shuan Ju Teh
Keyword(s):  
Antibiotic Resistance ◽  
Klebsiella Pneumoniae ◽  
Antibiotic Susceptibility ◽  
Efflux Pump ◽  
Outer Membrane Proteins ◽  
Multidrug Resistant ◽  
Efflux Pump Inhibitor ◽  
Pump System ◽  
Extended Spectrum Beta Lactamases ◽  
Amoxicillin Clavulanate

Abstract Multidrug-resistant (MDR) Klebsiella pneumoniae (K. pneumoniae) poses a serious public health threat. K. pneumoniae strains that produce extended-spectrum beta-lactamases (ESBL) are becoming increasingly reported in nosocomial and community-acquired infections. Besides resistance genes, integrons, and plasmids, altered membrane permeability caused by porin loss and energy-dependent efflux have also contributed to antibiotic resistance in K. pneumoniae. The objective of this study was to determine the correlation between the reduction of antibiotic susceptibility and overexpression of efflux pump as well as the lack of outer membrane proteins (OMPs) among clinical ESBLs resistant K. pneumoniae. The expression levels of ramA, acrA, ompK35 and ompK36 in 12 MDR K. pneumoniae strains with varying MICs levels were analyzed using quantitative real time-Polymerase Chain Reaction (qRT-PCR). The role of efflux pump on antibiotic resistance was also studied by using minimum inhibitory concentration (MICs) method with//without efflux pump inhibitor. The result indicated that the strains with highest resistance to cefotaxime showed the lowest level of ompK35 and ompK36 genes expression while the strains with lowest MIC level of resistance to cefotaxime showed the highest level of expression of acrA and ramA. Our finding also revealed the effect of efflux pump inhibitor phenyl-arginine-b-naphthylamide (PAβN) on the MIC levels of ceftazidime, amoxicillin-clavulanate and cefotaxime which were significantly reduced around 1–7 folds MIC levels. These results suggest that Efflux pump system and deficiently of OMPs contributing role in antibiotic susceptibility which should be taken seriously to prevent the treatment failure due to antimicrobial resistance.

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

2015 ◽  
Vol 59 (8) ◽  
pp. 4817-4825 ◽  
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.

scholarly journals Assessment of Minocycline and Polymyxin B Combination against Acinetobacter baumannii

2015 ◽  
Vol 59 (5) ◽  
pp. 2720-2725 ◽  
Author(s):  
Dana R. Bowers ◽  
Henry Cao ◽  
Jian Zhou ◽  
Kimberly R. Ledesma ◽  
Dongxu Sun ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Clinical Utility ◽  
Efflux Pump ◽  
Polymyxin B ◽  
Intracellular Concentration ◽  
Bacterial Cells ◽  
Efflux Pump Inhibitor ◽  
Content Type

ABSTRACTAntimicrobial resistance amongAcinetobacter baumanniiis increasing worldwide, often necessitating combination therapy. The clinical utility of using minocycline with polymyxin B is not well established. In this study, we investigated the activity of minocycline and polymyxin B against 1 laboratory isolate and 3 clinical isolates ofA. baumannii. Minocycline susceptibility testing was performed with and without an efflux pump inhibitor, phenylalanine-arginine β-naphthylamide (PAβN). The intracellular minocycline concentration was determined with and without polymyxin B (0.5 μg/ml). Time-kill studies were performed over 24 h using approximately 106CFU/ml of each strain with clinically relevant minocycline concentrations (2 μg/ml and 8 μg/ml), with and without polymyxin B (0.5 μg/ml). Thein vivoefficacy of the combination was assessed in a neutropenic murine pneumonia model. Infected animals were administered minocycline (50 mg/kg), polymyxin B (10 mg/kg), or both to achieve clinically equivalent exposures in humans. A reduction in the minocycline MIC (≥4×) was observed in the presence of PAβN. The intracellular concentration andin vitrobactericidal effect of minocycline were both enhanced by polymyxin B. With 2 minocycline-susceptible strains, the bacterial burden in lung tissue at 24 h was considerably reduced by the combination compared to monotherapy with minocycline or polymyxin B. In addition, the combination prolonged survival of animals infected with a minocycline-susceptible strain. Polymyxin B increased the intracellular concentration of minocycline in bacterial cells and enhanced the bactericidal activity of minocycline, presumably due to efflux pump disruption. The clinical utility of this combination should be further investigated.

scholarly journals Rescued chlorhexidine activity by resveratrol against carbapenem-resistant Acinetobacter baumannii via down-regulation of AdeB efflux pump

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243082
Author(s):  
Uthaibhorn Singkham-in ◽  
Paul G. Higgins ◽  
Dhammika Leshan Wannigama ◽  
Parichart Hongsing ◽  
Tanittha Chatsuwan
Keyword(s):  
Acinetobacter Baumannii ◽  
Ethidium Bromide ◽  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Intracellular Accumulation ◽  
Efflux Pump Inhibitor ◽  
Carbapenem Resistant ◽  
Efflux Pump Inhibition ◽  
Synergistic Mechanism ◽  
Time Kill

The aim of this study was to determine the activity and synergistic mechanisms of resveratrol in combination with chlorhexidine against carbapenem-resistant Acinetobacter baumannii clinical isolates. The activity of resveratrol plus antimicrobial agents was determined by checkerboard and time-kill assay against carbapenem-resistant A. baumannii isolated from patients at the King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Overexpression of efflux pumps that mediates chlorhexidine susceptibility was characterized by the ethidium bromide accumulation assay. The effect of resveratrol on the expression of efflux pump genes (adeB, adeJ, adeG abeS, and aceI) and the two-component regulators, adeR and adeS was determined by RT-qPCR. The combination of resveratrol and chlorhexidine resulted in strong synergistic and bactericidal activity against carbapenem-resistant A. baumannii. Up-regulation of adeB and aceI was induced by chlorhexidine. However, the addition of resveratrol increased chlorhexidine susceptibility with increased intracellular accumulation of ethidium bromide in A. baumannii indicating that resveratrol acts as an efflux pump inhibitor. Expression of adeB was significantly reduced in the combination of resveratrol with chlorhexidine indicating that resveratrol inhibits the AdeB efflux pump and restores chlorhexidine effect on A. baumannii. In conclusion, reduced adeB expression in A. baumannii was mediated by resveratrol suggesting that AdeB efflux pump inhibition contributes to the synergistic mechanism of resveratrol with chlorhexidine. Our finding highlights the potential importance of resveratrol in clinical applications.

scholarly journals EFFLUX PUMP OVEREXPRESSION PROFILING IN ACINETOBACTER BAUMANNII AND STUDY OF NEW 1-(1-NAPHTHYLMETHYL)-PIPERAZINE ANALOGS AS POTENTIAL EFFLUX INHIBITORS

2021 ◽  
Author(s):  
Morgane Choquet ◽  
Elodie Lohou ◽  
Etienne Pair ◽  
Pascal Sonnet ◽  
Catherine Mullie
Keyword(s):  
Antibiotic Resistance ◽  
Acinetobacter Baumannii ◽  
Inhibitory Activity ◽  
Efflux Pump ◽  
Parent Compound ◽  
Efflux Pumps ◽  
Quinoline Derivative ◽  
Genes Encoding ◽  
Efflux Pump Inhibitors ◽  
Therapeutic Alternatives

Overexpression of efflux pumps extruding antibiotics currently used for the treatment of Acinetobacter baumannii infections has been described as an important mechanism causing antibiotic resistance. The first aim of this work was to phenotypically evaluate the overexpression of efflux pumps on a collection of 124 ciprofloxacin resistant A. baumannii strains. An overexpression of genes encoding one or more efflux pumps was obtained for 19 out of the 34 strains with a positive phenotypic efflux (56%). The most frequent genes overexpressed were those belonging to the RND family, with adeJ being the most prevalent (50%). Interestingly, efflux pump genes coding for MATE and MFS families were also overexpressed quite frequently: abeM (32%) and abaQ (26%). The second aim was to synthesize 1-(1-NaphthylMethyl)-Piperazine analogs as potential new efflux pump inhibitors and biologically evaluate them against strains with a positive phenotypic efflux. Quinoline and pyridine analogs were found to be more effective than their parent compound 1-(1-NaphthylMethyl)-Piperazine. Stereochemistry also played an important part in the inhibitory activity as quinoline derivative ( R )-3a was identified as being the most effective and less cytotoxic. Its inhibitory activity was also correlated to the number of efflux pumps expressed by a strain. The results obtained in this work suggest that quinoline analogs of 1-(1-NaphthylMethyl)-Piperazine are promising leads in the development of new anti- Acinetobacter baumannii therapeutic alternatives, in combination with antibiotics for which an efflux-mediated resistance is suspected.

scholarly journals Efflux Pump Activity and Mutations Driving Multidrug Resistance in Acinetobacter baumannii at a Tertiary Hospital in Pretoria, South Africa

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Noel-David Nogbou ◽  
Granny M. Nkawane ◽  
Khanyisa Ntshane ◽  
Charles K. Wairuri ◽  
Dikwata T. Phofa ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Gene Mutation ◽  
Efflux Pump ◽  
Pcr Amplification ◽  
Tertiary Hospital ◽  
Gyra Gene ◽  
Efflux Pump Inhibitor ◽  
Pump System ◽  
Mechanism Of Resistance ◽  
Evolutionary Relatedness

Acinetobacter baumannii (A. baumannii) has developed several resistance mechanisms. The bacteria have been reported as origin of multiple outbreaks. This study aims to investigate the use of efflux pumps and quinolone resistance-associated genotypic mutations as mechanisms of resistance in A. baumannii isolates at a tertiary hospital. A total number of 103 A. baumannii isolates were investigated after identification and antimicrobial susceptibility testing by VITEK2 followed by PCR amplification of blaOXA-51. Conventional PCR amplification of the AdeABC efflux pump (adeB, adeS, and adeR) and quinolone (parC and gyrA) resistance genes were performed, followed by quantitative real-time PCR of AdeABC efflux pump genes. Phenotypic evaluation of efflux pump expression was performed by determining the difference between the MIC of tigecycline before and after exposure to an efflux pump inhibitor. The Sanger sequencing method was used to sequence the parC and gyrA amplicons. A phylogenetic tree was drawn using MEGA 4.0 to evaluate evolutionary relatedness of the strains. All the collected isolates were blaOXA-51-positive. High resistance to almost all the tested antibiotics was observed. Efflux pump was found in 75% of isolates as a mechanism of resistance. The study detected parC gene mutation in 60% and gyrA gene mutation in 85%, while 37% of isolates had mutations on both genes. A minimal evolutionary distance between the isolates was reported. The use of the AdeABC efflux pump system as an active mechanism of resistance combined with point mutation mainly in gyrA was shown to contribute to broaden the resistance spectrum of A. baumannii isolates.

scholarly journals The rise and the fall of a Pseudomonas aeruginosa epidemic lineage in a hospital

2020 ◽  
Author(s):  
Marie Petitjean ◽  
Paulo Juarez ◽  
Alexandre Meunier ◽  
Etienne Daguindau ◽  
Hélène Puja ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Infection Control ◽  
Efflux Pump ◽  
Bacterial Genome ◽  
Hospital Setting ◽  
Control Measures ◽  
Hospital Environment ◽  
Epidemic Strain ◽  
Over Time

AbstractThe biological features that allow a pathogen to survive in the hospital environment are mostly unknown. The extinction of bacterial epidemics in hospitals is mostly attributed to changes in medical practice, including infection control, but the role of bacterial adaptation has never been documented. We analyzed a collection of Pseudomonas aeruginosa isolates belonging to the Besançon Epidemic Strain (BES), responsible for a 12-year nosocomial outbreak, using a genotype-to-phenotype approach. Bayesian analysis estimated the emergence of the clone in the hospital five years before its opening, during the creation of its water distribution network made of copper. BES survived better than the reference strains PAO1 and PA14 in a copper solution due to a genomic island containing 13 metal-resistance genes and was specifically able to proliferate in the ubiquitous amoeba Vermamoeba vermiformis. Mutations affecting amino-acid metabolism, antibiotic resistance, lipopolysaccharide biosynthesis, and regulation were enriched during the spread of BES. Seven distinct regulatory mutations attenuated the overexpression of the genes encoding the efflux pump MexAB-OprM over time. The fitness of BES decreased over time in correlation with its genome size. Overall, the resistance to inhibitors and predators presumably aided the proliferation and propagation of BES in the plumbing system of the hospital. The pathogen further spread among patients via multiple routes of contamination. The decreased prevalence of patients infected by BES mirrored the parallel and convergent genomic evolution and reduction that affected bacterial fitness. Along with infection control measures, this may have participated in the extinction of BES in the hospital setting.ImportanceBacterial pathogens are responsible for nosocomial outbreaks, but the sources of contamination of the hospitals are mostly unclear and the role of bacterial evolution in the extinction of outbreaks has never been considered. Here, we found that an epidemic strain of the pathogen Pseudomonas aeruginosa contaminated the drinking water network of a hospital due to its tolerance to copper and predatory amoeba, both present in the water pipes. The extinction of the outbreak occurred concomitantly with parallel and convergent genome evolution and a reduction in the size of the bacterial genome that correlated with the fitness of the pathogen. Our data suggest that pathogen evolution participated in the extinction of an outbreak in a hospital setting.

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