scholarly journals Transposition of Tn125encoding the NDM-1 carbapenemase inAcinetobacter baumannii

2016 ◽  
pp. AAC.01755-16 ◽  
Author(s):  
Séverine Bontron ◽  
Patrice Nordmann ◽  
Laurent Poirel
Keyword(s):  
Acinetobacter Baumannii ◽  
Direct Evidence ◽  
Opportunistic Pathogen ◽  
Target Site ◽  
Gram Negative Bacteria ◽  
Transposition Frequency ◽  
Gram Negative ◽  
Temperature Changes ◽  
Site Consensus ◽  
Almost All

TheblaNDM-1gene encodes a carbapenemase that confers resistance to almost all β-lactams, including latest resort carbapenems. It is increasingly reported worldwide in nosocomial and community-acquired Gram-negative bacteria.Acinetobacter baumanniiis an important opportunistic pathogen considered as an intermediate reservoir for theblaNDM-1gene. In this species, theblaNDM-1gene is located within the Tn125composite transposon. The mechanism driving the mobility of Tn125has not yet been elucidated. Here we experimentally demonstrated transposition of Tn125inA. baumannii. Systematic 3-bp duplication of the target site, being signature of transposition, was evidenced. The target site consensus for Tn125transposition was found to be GC-enriched at the duplicated 3 bp and AT-rich in the vicinity. Transposition frequency was not influenced by temperature changes or by exposure to sub-inhibitory concentrations of various antibiotics. This work is the first direct evidence of the functionality of a composite transposon inA. baumannii. It provides a mechanistic clue for the dissemination of theblaNDM-1gene inAcinetobacterspp. and subsequently among Enterobacteriaceae.

scholarly journals Gram-Negative Bacteria Holding Together in a Biofilm: The Acinetobacter baumannii Way

2021 ◽  
Vol 9 (7) ◽  
pp. 1353
Author(s):  
Arianna Pompilio ◽  
Daniela Scribano ◽  
Meysam Sarshar ◽  
Giovanni Di Bonaventura ◽  
Anna Teresa Palamara ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Treatment Options ◽  
Public Health Problem ◽  
Opportunistic Pathogen ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
Antibiotic Resistant ◽  
Gram Negative ◽  
Abiotic Surfaces ◽  
Healthcare Associated

Bacterial biofilms are a serious public-health problem worldwide. In recent years, the rates of antibiotic-resistant Gram-negative bacteria associated with biofilm-forming activity have increased worrisomely, particularly among healthcare-associated pathogens. Acinetobacter baumannii is a critically opportunistic pathogen, due to the high rates of antibiotic resistant strains causing healthcare-acquired infections (HAIs). The clinical isolates of A. baumannii can form biofilms on both biotic and abiotic surfaces; hospital settings and medical devices are the ideal environments for A. baumannii biofilms, thereby representing the main source of patient infections. However, the paucity of therapeutic options poses major concerns for human health infections caused by A. baumannii strains. The increasing number of multidrug-resistant A. baumannii biofilm-forming isolates in association with the limited number of biofilm-eradicating treatments intensify the need for effective antibiofilm approaches. This review discusses the mechanisms used by this opportunistic pathogen to form biofilms, describes their clinical impact, and summarizes the current and emerging treatment options available, both to prevent their formation and to disrupt preformed A. baumannii biofilms.

scholarly journals Complete Genome Sequence of Lytic Bacteriophage LZ35 Infecting Acinetobacter baumannii Isolates

2016 ◽  
Vol 4 (6) ◽  
Author(s):  
Zhonghe Guo ◽  
Honglan Huang ◽  
Xiaolin Wu ◽  
Yuchong Hao ◽  
Yanbo Sun
Keyword(s):  
Acinetobacter Baumannii ◽  
Genome Sequence ◽  
Nosocomial Infections ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Opportunistic Pathogen ◽  
Lytic Bacteriophage ◽  
Gram Negative

Acinetobacter baumannii is a Gram-negative opportunistic pathogen that is frequently associated with nosocomial infections. Bacteriophages infecting A. baumannii can be used as effective agents to control these infections. Here, we announce the complete genome sequence of the lytic bacteriophage LZ35 infecting A. baumannii isolates.

scholarly journals Robust Suppression of Lipopolysaccharide Deficiency in Acinetobacter baumannii by Growth in Minimal Medium

2019 ◽  
Vol 201 (22) ◽  
Author(s):  
Emma Nagy ◽  
Richard Losick ◽  
Daniel Kahne
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Minimal Medium ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Growth Defects ◽  
Outer Leaflet ◽  
Morphological Defects ◽  
Outer Membrane Biogenesis

ABSTRACT Lipopolysaccharide (LPS) is normally considered to be essential for viability in Gram-negative bacteria but can be removed in Acinetobacter baumannii. Mutant cells lacking this component of the outer membrane show growth and morphological defects. Here, we report that growth rates equivalent to the wild type can be achieved simply by propagation in minimal medium. The loss of LPS requires that cells rely on phospholipids for both leaflets of the outer membrane. We show that growth rate in the absence of LPS is not limited by nutrient availability but by the rate of outer membrane biogenesis. We hypothesize that because cells grow more slowly, outer membrane synthesis ceases to be rate limiting in minimal medium. IMPORTANCE Gram-negative bacteria are defined by their asymmetric outer membrane that consists of phospholipids on the inner leaflet and lipopolysaccharide (LPS) in the outer leaflet. LPS is essential in all but a few Gram-negative species; the reason for this differential essentiality is not well understood. One species that can survive without LPS, Acinetobacter baumannii, shows characteristic growth and morphology phenotypes. We show that these phenotypes can be suppressed under conditions of slow growth and describe how LPS loss is connected to the growth defects. In addition to better defining the challenges A. baumannii cells face in the absence of LPS, we provide a new hypothesis that may explain the species-dependent conditional essentiality.

scholarly journals The Current Burden of Carbapenemases: Review of Significant Properties and Dissemination among Gram-Negative Bacteria

Antibiotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 186 ◽  
Author(s):  
Dalal Hammoudi Halat ◽  
Carole Ayoub Moubareck
Keyword(s):  
Clinical Importance ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Health Measures ◽  
Current Review ◽  
Serious Infections ◽  
Broad Variety ◽  
Almost All ◽  
The Impact ◽  
Bacterial Groups

Carbapenemases are β-lactamases belonging to different Ambler classes (A, B, D) and can be encoded by both chromosomal and plasmid-mediated genes. These enzymes represent the most potent β-lactamases, which hydrolyze a broad variety of β-lactams, including carbapenems, cephalosporins, penicillin, and aztreonam. The major issues associated with carbapenemase production are clinical due to compromising the activity of the last resort antibiotics used for treating serious infections, and epidemiological due to their dissemination into various bacteria across almost all geographic regions. Carbapenemase-producing Enterobacteriaceae have received more attention upon their first report in the early 1990s. Currently, there is increased awareness of the impact of nonfermenting bacteria, such as Acinetobacter baumannii and Pseudomonas aeruginosa, as well as other Gram-negative bacteria that are carbapenemase-producers. Outside the scope of clinical importance, carbapenemases are also detected in bacteria from environmental and zoonotic niches, which raises greater concerns over their prevalence, and the need for public health measures to control consequences of their propagation. The aims of the current review are to define and categorize the different families of carbapenemases, and to overview the main lines of their spread across different bacterial groups.

ETX2514 is a broad-spectrum β-lactamase inhibitor for the treatment of drug-resistant Gram-negative bacteria including Acinetobacter baumannii

2017 ◽  
Vol 2 (9) ◽  
Author(s):  
Thomas F. Durand-Réville ◽  
Satenig Guler ◽  
Janelle Comita-Prevoir ◽  
Brendan Chen ◽  
Neil Bifulco ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Broad Spectrum ◽  
Gram Negative Bacteria ◽  
Drug Resistant ◽  
Gram Negative ◽  
Lactamase Inhibitor

scholarly journals Functional and structural characterization of Serratia marcescens ExbB: determinants of the interaction with HasB/TonB

2021 ◽  
Author(s):  
Valérie Biou ◽  
Ricardo Jorge D Adaixo ◽  
Mohamed Chami ◽  
Pierre-Damien Coureux ◽  
Benoist Laurent ◽  
...  
Keyword(s):  
Serratia Marcescens ◽  
Molecular Motor ◽  
Opportunistic Pathogen ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
E Coli ◽  
New Class ◽  
Heme Acquisition ◽  
Shed Light

ExbBD is part of a cytoplasmic membrane molecular motor driven by the proton-motive force. It belongs to the larger family of motors involved in nutriment import across the outer membrane of Gram-negative bacteria (ExbBD), flagellar rotation (MotAB) or late steps of cell division in Gram-negative bacteria (TolQR). ExbB and ExbD are integral membrane proteins with three (ExbB) or one (ExbD) transmembrane segment. Here we have solved by single-particle cryo-EM the structures of ExbB alone and of the ExbB-ExbD complex of the opportunistic pathogen Serratia marcescens. ExbBSm alone behaves as a stable pentamer, and the complex displays the ExbB5-ExbD2 stoichiometry. This is similar to what has been observed for ExbB-ExbD complexes from Escherichia coli and Pseudomonas savastanoi as well as MotAB complexes from various species. We identified residues located in the first TM of ExbBSm and ExbBEc that are likely involved in the interaction with TonB/HasB and that are essential for function. ExbBSm has a ca. 40 residues long periplasmic extension absent in E. coli. Such long ExbBs are found in some Gammaproteobacteria, and several genera of Alphaproteobacteria. We show that this extension interacts with HasB, a dedicated TonB paralog from the heme acquisition system (Has) from S. marcescens. We also show that it is involved in heme acquisition via the Has system from S. marcescens. ExbBSm represents thus a new class of ExbB protein and our results shed light on the specificity determinants between the ExbB-ExbD complex and their associated TonB partners.

scholarly journals Acinetobacter baumannii Can Survive with an Outer Membrane Lacking Lipooligosaccharide Due to Structural Support from Elongasome Peptidoglycan Synthesis

mBio ◽  
2021 ◽  
Author(s):  
Brent W. Simpson ◽  
Marta Nieckarz ◽  
Victor Pinedo ◽  
Amanda B. McLean ◽  
Felipe Cava ◽  
...  
Keyword(s):  
Mechanical Strength ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Structural Support ◽  
Peptidoglycan Synthesis

Gram-negative bacteria have a multilayered cell envelope with a layer of cross-linked polymers (peptidoglycan) sandwiched between two membranes. Peptidoglycan was long thought to exclusively provide rigidity to the cell providing mechanical strength.

The Development of New Small-Molecule Inhibitors Targeting Bacterial Metallo-β-lactamases

2018 ◽  
Vol 18 (10) ◽  
pp. 834-843 ◽  
Author(s):  
Ping Wang ◽  
Jing Cheng ◽  
Cong-Cong Liu ◽  
Kai Tang ◽  
Feng Xu ◽  
...  
Keyword(s):  
Small Molecule ◽  
Horizontal Transfer ◽  
Gram Negative Bacteria ◽  
Drug Resistant ◽  
Gram Negative ◽  
Major Threat ◽  
Extensively Drug Resistant ◽  
Genes Encoding ◽  
Recent Developments ◽  
Almost All

Metallo-β-lactamases (MBLs) are a family of Zn(II)-dependent enzymes that can hydrolyze almost all β-lactam antibiotics. Horizontal transfer of the genes encoding MBLs among Gram-negative bacteria pathogens has led to the emergence of extensively drug-resistant pathogens, which now represent a major threat to human health. As there is not to date yet a clinically available MBL inhibitor, the discovery of new MBL inhibitors has great urgency. This review highlights the recent developments in the discovery of small-molecule MBL inhibitors.

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