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.

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.

scholarly journals Genomic Analysis of Reduced Susceptibility to Tigecycline in Enterococcus faecium

2014 ◽  
Vol 59 (1) ◽  
pp. 239-244 ◽  
Author(s):  
Vincent Cattoir ◽  
Christophe Isnard ◽  
Thibaud Cosquer ◽  
Arlène Odhiambo ◽  
Fiona Bucquet ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Substitution ◽  
Enterococcus Faecium ◽  
Efflux Pump ◽  
Acquired Resistance ◽  
Ribosomal Subunit ◽  
Genomic Analysis ◽  
Lactate Oxidase ◽  
Content Type

ABSTRACTTigecycline (TIG) is approved for use for the treatment of complicated intra-abdominal infections, skin and skin structure infections, as well as pneumonia. Acquired resistance or reduced susceptibility to TIG has been observed in Gram-negative rods, has seldom been reported in Gram-positive organisms, and has not yet been reported inEnterococcus faecium. Using the serial passage method,in vitromutant AusTig andin vitromutants HMtig1 and HMtig2 with decreased TIG susceptibility (MICs, 0.25 μg/ml) were obtained from strainsE. faeciumAus0004 and HM1070 (MICs, 0.03 μg/ml), respectively. In addition, two vancomycin-resistantE. faeciumclinical isolates (EF16 and EF22) with reduced susceptibility to TIG (MICs, 0.5 and 0.25 μg/ml, respectively) were studied. Compared to the wild-type strains, thein vitromutants also showed an increase in the MICs of other tetracyclines. An efflux mechanism did not seem to be involved in the reduced TIG susceptibility, since the presence of efflux pump inhibitors (reserpine or pantoprazole) did not affect the MICs of TIG. Whole-genome sequencing of AusTig was carried out, and genomic comparison with the Aus0004 genome was performed. Four modifications leading to an amino acid substitution were found. These mutations affected therpsJgene (efau004_00094, coding for the S10 protein of the 30S ribosomal subunit),efau004_01228(encoding a cation transporter),efau004_01636(coding for a hypothetical protein), andefau004_02455(encoding thel-lactate oxidase). The four other strains exhibiting reduced TIG susceptibility were screened for the candidate mutations. This analysis revealed that three of them showed an amino acid substitution in the same region of the RpsJ protein. In this study, we characterized for the first time genetic determinants linked to reduced TIG susceptibility in enterococci.

scholarly journals Carbapenem-Resistant Acinetobacter baumannii Isolates from Tunisia Producing the OXA-58-Like Carbapenem-Hydrolyzing Oxacillinase OXA-97

2008 ◽  
Vol 52 (5) ◽  
pp. 1613-1617 ◽  
Author(s):  
Laurent Poirel ◽  
Wejdene Mansour ◽  
Olfa Bouallegue ◽  
Patrice Nordmann
Keyword(s):  
Amino Acid ◽  
Acinetobacter Baumannii ◽  
Amino Acid Substitution ◽  
Multidrug Resistant ◽  
Single Amino Acid Substitution ◽  
Single Amino Acid ◽  
The Novel ◽  
Cloning And Sequencing ◽  
Carbapenem Resistant ◽  
Genetic Structures

ABSTRACT The basis of the β-lactam resistance of 39 multidrug-resistant Acinetobacter baumannii isolates recovered from hospitalized patients was studied. These isolates were collected from 2001 to 2005 at the Sahloul Hospital in Sousse, Tunisia. They belonged to two distinct clones. One clone that grouped 19 isolates produced a carbapenem-hydrolyzing oxacillinase, OXA-97, that differed from OXA-58 by a single amino acid substitution and conferred the same β-lactam resistance profile as OXA-58. The bla OXA-97 gene was located on plasmids that varied in size in 18 isolates and was chromosomally located in a single isolate. Cloning and sequencing identified genetic structures surrounding the bla OXA-97 gene similar to those reported to be adjacent to the bla OXA-58 gene. In addition, the novel ISAba8 element (which is of the IS21 family) was identified. This is the first report of the nosocomial spread of carbapenemase producers in A. baumannii isolates in Africa.

Can proteomics elucidate mechanisms of antimicrobial resistance in Neisseria gonorrhoeae that whole genome sequencing is unable to identify? An analysis of protein expression within the 2016 WHO N. gonorrhoeae reference strains

2019 ◽  
Vol 96 (5) ◽  
pp. 330-334 ◽  
Author(s):  
Jianhe Peng ◽  
Julie Russell ◽  
Sarah Alexander
Keyword(s):  
Antimicrobial Resistance ◽  
Neisseria Gonorrhoeae ◽  
Protein Expression ◽  
Stress Responses ◽  
Atp Hydrolysis ◽  
Efflux Pump ◽  
Expression Profiles ◽  
Internal Standard ◽  
Protein Expression Profiles ◽  
Reference Strains

ObjectivesAntimicrobial resistance (AMR) in Neisseria gonorrhoeae is of increasing concern. This study established a quantitative, scalable proteomics method to examine the WHO panel of N. gonorrhoeae isolates with completed closed genomic sequences and well-defined phenotypical and genotypical AMR patterns, to gain a greater understanding of AMR in N. gonorrhoeae.Methods14 WHO reference strains were propagated, pooled stable isotope labelled lysates were used as an internal standard (IS). Protein lysates were mixed with IS, digested with trypsin and fractionated before analysis by nano-LC/MS/MS, in triplicate. The susceptible strain WHO F was used as reference to which the proteomic profiles of other strains were compared. Hierarchical clustering and permutation adjusted t-tests were performed to find proteins with significant fold changes.ResultsStandardised, reproducible protein expression profiles in N. gonorrhoeae reference strains were produced. Strains that have previously been shown to be highly similar using genomics, displayed different proteomic profiles. Several proteins from efflux pumps to stress responses, such as oxidative stress, toxin/antitoxin systems, were found to be altered in AMR strains. LtgE was upregulated in strains which displayed chromosomally mediated resistance to penicillin. MacB (the ATP hydrolysis part of macrolide efflux pump MacA-B), was ~twofold upregulated in WHO V (MIC of azithromycin >256 mg/L) and maybe associated with azithromycin resistance.ConclusionsA robust method was developed to study protein expression in N. gonorrhoeae. The proteome profiles could differentiate genetically similar stains. This study identified complex mechanisms in N. gonorrhoeae which may be associated with AMR.

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