Characterization of Amino Acid Substitutions in the Two-Component Regulatory System AdeRS Identified in Multidrug-Resistant Acinetobacter baumannii

The active efflux of antimicrobials by bacteria can lead to antimicrobial resistance and persistence and can affect multiple different classes of antimicrobials. Efflux pumps are tightly regulated, and their overexpression can be mediated by changes in their regulators.

Download Full-text

Molecular characterization of lpxACD and pmrA/B two-component regulatory system in the colistin resistance Acinetobacter baumannii clinical isolates

Gene Reports ◽

10.1016/j.genrep.2020.100952 ◽

2020 ◽

Vol 21 ◽

pp. 100952

Author(s):

Mohammad Reza Kandehkar Ghahraman ◽

Hossein Hosseini-Nave ◽

Omid Azizi ◽

Mohammad Reza Shakibaie ◽

Hamid Reza Mollaie ◽

...

Keyword(s):

Acinetobacter Baumannii ◽

Molecular Characterization ◽

Regulatory System ◽

Clinical Isolates ◽

Colistin Resistance ◽

Two Component

Download Full-text

RND-Type Efflux Pumps in Multidrug-Resistant Clinical Isolates of Acinetobacter baumannii: Major Role for AdeABC Overexpression and AdeRS Mutations

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02556-12 ◽

2013 ◽

Vol 57 (7) ◽

pp. 2989-2995 ◽

Cited By ~ 113

Author(s):

Eun-Jeong Yoon ◽

Patrice Courvalin ◽

Catherine Grillot-Courvalin

Keyword(s):

Acinetobacter Baumannii ◽

Efflux Pump ◽

Regulatory System ◽

Multidrug Resistant ◽

Clinical Isolates ◽

Clinical Settings ◽

Two Component System ◽

Content Type ◽

High Incidence ◽

Two Component

ABSTRACTIncreased expression of chromosomal genes for resistance-nodulation-cell division (RND)-type efflux systems plays a major role in the multidrug resistance (MDR) ofAcinetobacter baumannii. However, the relative contributions of the three most prevalent pumps, AdeABC, AdeFGH, and AdeIJK, have not been evaluated in clinical settings. We have screened 14 MDR clinical isolates shown to be distinct on the basis of multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) for the presence and overexpression of the three Ade efflux systems and analyzed the sequences of the regulators AdeRS, a two-component system, for AdeABC and AdeL, a LysR-type regulator, for AdeFGH. GeneadeBwas detected in 13 of 14 isolates, andadeGand the intrinsicadeJgene were detected in all strains. Significant overexpression ofadeBwas observed in 10 strains, whereas only 7 had moderately increased levels of expression of AdeFGH, and none overexpressed AdeIJK. Thirteen strains had reduced susceptibility to tigecycline, but there was no correlation between tigecycline MICs and the levels of AdeABC expression, suggesting the presence of other mechanisms for tigecycline resistance. No mutations were found in the highly conserved LysR regulator of the nine strains expressing AdeFGH. In contrast, functional mutations were found in conserved domains of AdeRS in all the strains that overexpressed AdeABC with two mutational hot spots, one in AdeS near histidine 149 suggesting convergent evolution and the other in the DNA binding domain of AdeR compatible with horizontal gene transfer. This report outlines the high incidence of AdeABC efflux pump overexpression in MDRA. baumanniias a result of a variety of single mutations in the corresponding two-component regulatory system.

Download Full-text

Characterization of a two-component regulatory system from Acinetobacter baumannii that controls biofilm formation and cellular morphology

Microbiology ◽

10.1099/mic.0.2008/019471-0 ◽

2008 ◽

Vol 154 (11) ◽

pp. 3398-3409 ◽

Cited By ~ 146

Author(s):

Andrew P. Tomaras ◽

Michael J. Flagler ◽

Caleb W. Dorsey ◽

Jennifer A. Gaddy ◽

Luis A. Actis

Keyword(s):

Acinetobacter Baumannii ◽

Biofilm Formation ◽

Regulatory System ◽

Cellular Morphology ◽

Two Component

Download Full-text

Development of an in vivo Assay for Mistranslation: Inducing Activity of Pollutants and Characterization of Amino Acid Substitutions.

10.21236/ada137069 ◽

1983 ◽

Author(s):

J. N. Reeve ◽

J. B. Rice

Keyword(s):

Amino Acid ◽

Amino Acid Substitutions ◽

In Vivo Assay

Download Full-text

Botanicals and phytochemicals from the bark of Hypericum roeperianum (Hypericaceae) had strong antibacterial activity and showed synergistic effects with antibiotics against multidrug-resistant bacteria expressing active efflux pumps.

Journal of Ethnopharmacology ◽

10.1016/j.jep.2021.114257 ◽

2021 ◽

pp. 114257

Author(s):

Olive Monique F. Demgne ◽

Francois Damen ◽

Aimé G. Fankam ◽

Michel-Gael F. Guefack ◽

Brice E.N. Wamba ◽

...

Keyword(s):

Antibacterial Activity ◽

Synergistic Effects ◽

Efflux Pumps ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Multidrug Resistant Bacteria ◽

Active Efflux

Download Full-text

Characterization of H9N2 influenza A viruses isolated from chicken products imported into Japan from China

Epidemiology and Infection ◽

10.1017/s0950268806006728 ◽

2006 ◽

Vol 135 (3) ◽

pp. 386-391 ◽

Cited By ~ 13

Author(s):

M. MASE ◽

M. ETO ◽

K. IMAI ◽

K. TSUKAMOTO ◽

S. YAMAGUCHI

Keyword(s):

Influenza Virus ◽

Amino Acid ◽

Avian Influenza ◽

Avian Influenza Virus ◽

Influenza A ◽

H9n2 Virus ◽

Amino Acid Substitutions ◽

Influenza A Viruses ◽

Potential Sources

We characterized eleven H9N2 influenza A viruses isolated from chicken products imported from China. Genetically they were classified into six distinct genotypes, including five already known genotypes and one novel genotype. This suggested that such multiple genotypes of the H9N2 virus have possibly already become widespread and endemic in China. Two isolates have amino-acid substitutions that confer resistance to amantadine in the M2 region, and this supported the evidence that this mutation might be a result of the wide application of amantadine for avian influenza treatment in China. These findings emphasize the importance of surveillance for avian influenza virus in this region, and of quarantining imported chicken products as potential sources for the introduction of influenza virus.

Download Full-text

Molecular characterization of a 13-amino acid deletion in VP1 (1D) protein and novel amino acid substitutions in 3D polymerase protein of foot and mouth disease virus subtype A/Iran87

Journal of Veterinary Science ◽

10.4142/jvs.2011.12.4.363 ◽

2011 ◽

Vol 12 (4) ◽

pp. 363 ◽

Cited By ~ 2

Author(s):

Majid Esmaelizad ◽

Saber Jelokhani-Niaraki ◽

Khadije Hashemnejad ◽

Morteza Kamalzadeh ◽

Mohsen Lotfi

Keyword(s):

Amino Acid ◽

Molecular Characterization ◽

Disease Virus ◽

Foot And Mouth Disease ◽

Amino Acid Substitutions ◽

Amino Acid Deletion ◽

Mouth Disease Virus ◽

Subtype A ◽

Virus Subtype

Download Full-text

Molecular characterization of multidrug resistant strains of Acinetobacter baumannii isolated from pediatric intensive care unit in a Chinese tertiary hospital

BMC Infectious Diseases ◽

10.1186/s12879-018-3511-0 ◽

2018 ◽

Vol 18 (1) ◽

Cited By ~ 7

Author(s):

Yili Chen ◽

Lu Ai ◽

Penghao Guo ◽

Han Huang ◽

Zhongwen Wu ◽

...

Keyword(s):

Intensive Care Unit ◽

Intensive Care ◽

Acinetobacter Baumannii ◽

Molecular Characterization ◽

Pediatric Intensive Care Unit ◽

Pediatric Intensive Care ◽

Tertiary Hospital ◽

Multidrug Resistant ◽

Resistant Strains

Download Full-text

Non-Penicillin-Susceptible Streptococcus suis Isolated from Humans

Pathogens ◽

10.3390/pathogens10091178 ◽

2021 ◽

Vol 10 (9) ◽

pp. 1178

Author(s):

Nichari Bamphensin ◽

Peechanika Chopjitt ◽

Rujirat Hatrongjit ◽

Parichart Boueroy ◽

Nahuel Fittipaldi ◽

...

Keyword(s):

Amino Acid ◽

Antimicrobial Resistance ◽

Resistance Genes ◽

Streptococcus Suis ◽

Amino Acid Substitutions ◽

Continuous Control ◽

Antimicrobial Resistance Genes ◽

Genes Encoding ◽

Invasive Infections ◽

Almost All

Streptococcus suis is a pathogen that causes invasive infections in humans and pigs. In this study, 448 S. suis isolates recovered from human infections in Thailand were characterized with regard to their antimicrobial susceptibility and antimicrobial resistance genes, including, for non-penicillin-susceptible isolates, sequence analyses of five genes encoding penicillin-binding proteins (pbp1a, pbp1b, pbp2a, pbp2b, and pbp2x). All 448 isolates were susceptible to cefepime and ceftriaxone, whereas 99.6%, 91.7%, and 72.9% of the isolates were susceptible to levofloxacin, penicillin, and chloramphenicol, respectively. Almost all isolates were resistant to tetracycline (98.2%), clindamycin (94%), erythromycin (92.4%), and azithromycin (82.6%). Genes tet(O) and ermB were the predominant resistance genes detected among macrolide- and tetracycline-resistant isolates. A total of 37 out of 448 isolates (8.2%) showed intermediately resistance to penicillin. Most of these isolates (59.5%) belonged to serotype 2-ST233. Comparison of the predicted translated sequences of five PBP proteins of a penicillin-susceptible isolate (strain P1/7) to the respective PBP sequences of ten non-penicillin-susceptible isolates revealed multiple amino acid substitutions. Isolates of CC221/234 showed highly variable amino acid substitutions in all PBP proteins. An ST104 isolate had a higher number of amino acid substitutions in PBP2X. Isolates belonging to CC233/379 had numerous substitutions in PBP2B and PBP2X. ST25 isolates exhibited fewer amino acid substitutions than isolates of other STs in all five PBPs. The antimicrobial resistance of S. suis is increasing worldwide; therefore, restrictions on antimicrobial use, continuous control, and the surveillance of this bacterium throughout the pork supply chain are crucial for ensuring public health and must be a priority concern.

Download Full-text