scholarly journals Growth phase-dependent expression of RND efflux pump- and outer membrane porin-encoding genes in Acinetobacter baumannii ATCC 19606

2011 ◽  
Vol 67 (3) ◽  
pp. 569-572 ◽  
Author(s):  
D. Fernando ◽  
A. Kumar
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Growth Phase ◽  
Efflux Pump ◽  
Outer Membrane Porin ◽  
Rnd Efflux Pump ◽  
Encoding Genes

Tigecycline efflux in Acinetobacter baumannii is mediated by TetA in synergy with RND-type efflux transporters

2020 ◽  
Vol 75 (5) ◽  
pp. 1135-1139 ◽  
Author(s):  
Wuen Ee Foong ◽  
Jochen Wilhelm ◽  
Heng-Keat Tam ◽  
Klaas M Pos
Keyword(s):  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Gene Knockout ◽  
Drug Susceptibility ◽  
Major Facilitator Superfamily ◽  
Rt Pcr ◽  
E Coli ◽  
Rnd Efflux Pump ◽  
Major Facilitator

Abstract Objectives To investigate the role of Major Facilitator Superfamily (MFS)-type transporters from Acinetobacter baumannii AYE in tigecycline efflux. Methods Two putative tetracycline transporter genes of A. baumannii AYE (tetA and tetG) were heterologously expressed in Escherichia coli and drug susceptibility assays were conducted with tigecycline and three other tetracycline derivatives. The importance of TetA in tigecycline transport in A. baumannii was determined by complementation of tetA in WT and Resistance Nodulation cell Division (RND) gene knockout strains of A. baumannii ATCC 19606. Gene expression of the MFS-type tetA gene and RND efflux pump genes adeB, adeG and adeJ in A. baumannii AYE in the presence of tigecycline was analysed by quantitative real-time RT–PCR. Results Overproduction of TetA or TetG conferred resistance to doxycycline, minocycline and tetracycline in E. coli. Cells expressing tetA, but not those expressing tetG, conferred resistance to tigecycline, implying that TetA is a determinant for tigecycline transport. A. baumannii WT and RND-knockout strains complemented with plasmid-encoded tetA are significantly less susceptible to tigecycline compared with non-complemented strains. Efflux pump genes tetA and adeG are up-regulated in A. baumannii AYE in the presence of subinhibitory tigecycline concentrations. Conclusions TetA plays an important role in tigecycline efflux of A. baumannii by removing the drug from cytoplasm to periplasm and, subsequently, the RND-type transporters AdeABC and AdeIJK extrude tigecycline across the outer membrane. When challenged with tigecycline, tetA is up-regulated in A. baumannii AYE. Synergy between TetA and the RND-type transporters AdeABC and/or AdeIJK appears necessary for A. baumannii to confer higher tigecycline resistance via drug efflux.

Efflux Pump Overexpression in Conjunction with Alternation of Outer Membrane Protein May Induce Acinetobacter baumannii Resistant to Imipenem

Chemotherapy ◽  
2011 ◽  
Vol 57 (1) ◽  
pp. 77-84 ◽  
Author(s):  
LiuLin Luo ◽  
XiaoFei Jiang ◽  
Qiong Wu ◽  
LiMing Wei ◽  
JianHua Li ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Efflux Pump

scholarly journals AbuO, a TolC-Like Outer Membrane Protein of Acinetobacter baumannii, Is Involved in Antimicrobial and Oxidative Stress Resistance

2014 ◽  
Vol 59 (2) ◽  
pp. 1236-1245 ◽  
Author(s):  
Vijaya Bharathi Srinivasan ◽  
Vasanth Vaidyanathan ◽  
Govindan Rajamohan
Keyword(s):  
Oxidative Stress ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Outer Membrane Proteins ◽  
Major Facilitator Superfamily ◽  
Pcr Analysis ◽  
Content Type ◽  
Major Facilitator ◽  
And Oxidative Stress

ABSTRACTAlthoughAcinetobacter baumanniiis well accepted as a nosocomial pathogen, only a few of the outer membrane proteins (OMPs) have been functionally characterized. In this study, we demonstrate the biological functions of AbuO, a homolog of TolC fromEscherichia coli. Inactivation ofabuOled to increased sensitivity to high osmolarity and oxidative stress challenge. The ΔabuOmutant displayed increased susceptibility to antibiotics, such as amikacin, carbenicillin, ceftriaxone, meropenem, streptomycin, and tigecycline, and hospital-based disinfectants, such as benzalkonium chloride and chlorhexidine. The reverse transcription (RT)-PCR analysis indicated increased expression of efflux pumps (resistance nodulation cell division [RND] efflux pumpacrD, 8-fold; SMR-typeemrEhomolog, 12-fold; and major facilitator superfamily [MFS]-typeampGhomolog, 2.7-fold) and two-component response regulators (baeR, 4.67-fold;ompR, 10.43-fold) in the ΔabuOmutant together with downregulation ofrstA(4.22-fold) and the pilin chaperone (9-fold). The isogenic mutant displayed lower virulence in a nematode model (P< 0.01). Experimental evidence for the binding of MerR-type transcriptional regulator SoxR to radiolabeledabuOpromoter suggests regulation ofabuOby SoxR inA. baumannii.

scholarly journals AmpC and OprD Are Not Involved in the Mechanism of Imipenem Hypersusceptibility among Pseudomonas aeruginosa Isolates Overexpressing the mexCD-oprJ Efflux Pump

2005 ◽  
Vol 49 (11) ◽  
pp. 4763-4766 ◽  
Author(s):  
Daniel J. Wolter ◽  
Nancy D. Hanson ◽  
Philip D. Lister
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Outer Membrane Porin

ABSTRACT Pseudomonas aeruginosa strains that overexpress mexCD-oprJ become hypersusceptible to imipenem. Disruption of AmpC induction has been suggested to cause this phenotype. However, data from this study demonstrate that hypersusceptibility to imipenem can develop without changes in ampC expression or AmpC activity. Furthermore, hypersusceptibility is not caused by changes in expression of the outer membrane porin, OprD.

scholarly journals Triclosan Can Select for an AdeIJK-Overexpressing Mutant of Acinetobacter baumannii ATCC 17978 That Displays Reduced Susceptibility to Multiple Antibiotics

2014 ◽  
Vol 58 (11) ◽  
pp. 6424-6431 ◽  
Author(s):  
Dinesh M. Fernando ◽  
Wayne Xu ◽  
Peter C. Loewen ◽  
George G. Zhanel ◽  
Ayush Kumar
Keyword(s):  
Acinetobacter Baumannii ◽  
Efflux Pump ◽  
Resistant Mutant ◽  
Dilution Method ◽  
Gene Encoding ◽  
Content Type ◽  
Resistance Nodulation Division ◽  
Triclosan Resistance ◽  
Encoding Genes ◽  
Multiple Antibiotics

ABSTRACTIn order to determine if triclosan can select for mutants ofAcinetobacter baumanniiATCC 17978 that display reduced susceptibilities to antibiotics, we isolated a triclosan-resistant mutant,A. baumanniiAB042, by serial passaging ofA. baumanniiATCC 17978 in growth medium supplemented with triclosan. The antimicrobial susceptibility of AB042 was analyzed by the 2-fold serial dilution method. Expression of five different resistance-nodulation-division (RND) pump-encoding genes (adeB,adeG,adeJ,A1S_2818, andA1S_3217), two outer membrane porin-encoding genes (carOandoprD), and the MATE family pump-encoding geneabeMwas analyzed using quantitative reverse transcriptase (qRT) PCR.A. baumanniiAB042 exhibited elevated resistance to multiple antibiotics, including piperacillin-tazobactam, doxycycline, moxifloxacin, ceftriaxone, cefepime, meropenem, doripenem, ertapenem, ciprofloxacin, aztreonam, tigecycline, and trimethoprim-sulfamethoxazole, in addition to triclosan. Genome sequencing ofA. baumanniiAB042 revealed a116G→V mutation infabI, the gene encoding the target enzyme for triclosan. Expression analysis of efflux pumps showed overexpression of the AdeIJK pump, and sequencing ofadeN, the gene that encodes the repressor of theadeIJKoperon, revealed a 73-bp deletion which would cause a premature termination of translation, resulting in an inactive truncated AdeN protein. This work shows that triclosan can select for mutants ofA. baumanniithat display reduced susceptibilities to multiple antibiotics from chemically distinct classes in addition to triclosan resistance. This multidrug resistance can be explained by the overexpression of the AdeIJK efflux pump.

scholarly journals Comparison of the A. baumannii reference strains ATCC 17978 and ATCC 19606 in antimicrobial resistance mediated by the AdeABC efflux pump

2021 ◽  
Author(s):  
K. Lucaßen ◽  
S. Gerson ◽  
K. Xanthopoulou ◽  
J. Wille ◽  
T. Wille ◽  
...  
Keyword(s):  
Amino Acid ◽  
Antimicrobial Resistance ◽  
Acinetobacter Baumannii ◽  
Differential Expression ◽  
Amino Acid Substitution ◽  
Efflux Pump ◽  
Rnd Efflux Pump ◽  
Reference Strains

The Acinetobacter baumannii RND efflux pump AdeABC is regulated by the 2-component regulator AdeRS. In this study, we compared regulation and expression of AdeABC of the reference strains ATCC 17978 and ATCC 19606. A clearly stronger efflux activity was demonstrated for ATCC 19606. An amino acid substitution at residue 172 of adeS was identified as potential cause for differential expression of the pump. Therefore, we recommend caution with exclusively using single reference strains for research.

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