Search results for "Colistin"
showing 10 items of 30 documents
Production of Norspermidine Contributes to Aminoglycoside Resistance in pmrAB Mutants of Pseudomonas aeruginosa
2019
Emergence of resistance to polymyxins in Pseudomonas aeruginosa is mainly due to mutations in two-components systems, that promote addition of 4-amino-4-deoxy-L-arabinose to the lipopolysaccharide (LPS) through upregulation of operon arnBCADTEF-ugd (arn) expression. Here, we demonstrate that mutations occurring in different domains of histidine kinase PmrB or in response regulator PmrA result in coresistance to aminoglycosides and colistin. All seventeen clinical strains tested exhibiting such a cross-resistance phenotype were found to be pmrAB mutants. As shown by gene deletion experiments, the decreased susceptibility of the mutants to aminoglycosides was independent from operon arn but r…
Branched High Molecular Weight Glycopolypeptide With Broad-Spectrum Antimicrobial Activity for the Treatment of Biofilm Related Infections.
2017
There are few therapeutic options to simultaneously tackle Staphylococcus aureus and Pseudomonas aeruginosa, two of the most relevant nosocomial and antibiotic-resistant pathogens responsible for implant, catheters and wound severe infections. The design and synthesis of polymers with inherent antimicrobial activity have gained increasing attention as a safe strategy to treat multi-drug-resistant microbes. Here, we tested the activity of a new polymeric derivative with glycopolypeptide architecture (PAA-VC) bearing l-arginine, vancomycin, and colistin as side chains acting against multiple targets, which give rise to a broad spectrum antimicrobial activity favorably combining specific and n…
Mechanisms of Resistance to Ceftolozane/Tazobactam in Pseudomonas aeruginosa : Results of the GERPA Multicenter Study
2020
ABSTRACT Resistance mechanisms of Pseudomonas aeruginosa to ceftolozane/tazobactam (C/T) were assessed on a collection of 420 nonredundant strains nonsusceptible to ceftazidime (MIC > 8 μg/ml) and/or imipenem (>4 μg/ml), collected by 36 French hospital laboratories over a one-month period (the GERPA study). Rates of C/T resistance (MIC > 4/4 μg/ml) were equal to 10% in this population (42/420 strains), and 23.2% (26/112) among the isolates resistant to both ceftazidime and imipenem. A first group of 21 strains (50%) was found to harbor various extended-spectrum β-lactamases (1 OXA-14; 2 OXA-19; 1 OXA-35; 1 GES-9; and 3 PER-1), carbapenemases (2 GES-5; 1 IMP-8; and 8 VIM-2), or both (1 VIM-2…
Near-infrared light-responsive and antibacterial injectable hydrogels with antioxidant activity based on a Dopamine-functionalized Gellan Gum for wou…
2022
The development of wound dressings with combined antioxidant, antibacterial and tissue adhesion functions has been a difficult medical task for the treatment of wound infections. We synthetized a dopamine and PEG functionalized Gellan Gum (GG) to produce an injectable hydrogel with radical scavenging activity having both specific and aspecific antibiotic/antimicrobial properties. Using starting GG with different molecular weights, we obtained two derivatives that have been used to prepare the gel precursor dispersion, that undergoes gelation in the presence of colistin and dried microparticles (MPs) functionalized on the surface with polydopamine (pDA). Both were used to dope the hydrogel, …
Didymellanosine, a new decahydrofluorene analogue, and ascolactone C from Didymella sp. IEA-3B.1, an endophyte of Terminalia catappa
2020
Didymellanosine (1), the first analogue of the decahydrofluorene-class of natural products bearing a 13-membered macrocyclic alkaloid conjugated with adenosine, and a new benzolactone derivative, ascolactone C (4) along with eight known compounds (2, 3, 5–10), were isolated from a solid rice fermentation of the endophytic fungus Didymella sp. IEA-3B.1 derived from the host plant Terminalia catappa. In addition, ascochitamine (11) was obtained when (NH4)2SO4 was added to rice medium and is reported here for the first time as a natural product. Didymellanosine (1) displayed strong activity against the murine lymphoma cell line L5178Y, Burkitt's lymphoma B cells (Ramos) and adult lymphoblastic…
The Efflux Pump MexXY/OprM Contributes to the Tolerance and Acquired Resistance of Pseudomonas aeruginosa to Colistin
2020
The intrinsic resistance of Pseudomonas aeruginosa to polymyxins in part relies on the addition of 4-amino-4-deoxy-l-arabinose (Ara4N) molecules to the lipid A of lipopolysaccharide (LPS), through induction of operon arnBCADTEF-ugd (arn) expression. As demonstrated previously, at least three two-component regulatory systems (PmrAB, ParRS, and CprRS) are able to upregulate this operon when bacteria are exposed to colistin. In the present study, gene deletion experiments with the bioluminescent strain PAO1::lux showed that ParRS is a key element in the tolerance of P. aeruginosa to this last-resort antibiotic (i.e., resistance to early drug killing). Other loci of the ParR regulon, such as th…
Spanish Consensus on the Prevention and Treatment of Pseudomonas aeruginosa Bronchial Infections in Cystic Fibrosis Patients
2014
Pseudomonas aeruginosa is the main pathogen in bronchopulmonary infections in cystic fibrosis (CF) patients. It can only be eradicated at early infection stages while reduction of its bacterial load is the therapeutic goal during chronic infection or exacerbations. Neonatal screening and pharmacokinetic/pharmacodynamic knowledge has modified the management of CF-patients. A culture based microbiological follow-up should be performed in patients with no infection with P. aeruginosa. At initial infection, inhaled colistin (0,5-2 MU/tid), tobramycin (300 mg/bid) or aztreonam (75 mg/tid) with or without oral ciprofloxacin (15-20 mg/kg/bid, 2-3 weeks) are recommended. In chronic infections, trea…
KPC - 3 Klebsiella pneumoniae ST258 clone infection in postoperative abdominal surgery patients in an intensive care setting: analysis of a case seri…
2013
Background: Abdominal surgery carries significant morbidity and mortality, which is in turn associated with an enormous use of healthcare resources. We describe the clinical course of 30 Intensive Care Unit (ICU) patients who underwent abdominal surgery and showed severe infections caused by Klebsiella pneumoniae sequence type (ST) 258 producing K. pneumoniae carbapenemase (KPC-Kp). The aim was to evaluate risk factors for mortality and the impact of a combination therapy of colistin plus recommended regimen or higher dosage of tigecycline. Methods: A prospective assessment of severe monomicrobial KPC-Kp infections occurring after open abdominal surgery carried out from August 2011 to Augus…
Coste-efectividad de la suspensión del tratamiento con colistina inhalada en los pacientes con bronquiectasias del adulto no debidas a fibrosis quíst…
2018
Introducción Las bronquiectasias no debidas a fibrosis quística son, en frecuencia, la tercera enfermedad inflamatoria crónica de la vía aérea, después del asma y de la enfermedad pulmonar obstructiva crónica, y están en estrecha relación con ambas. El número de casos diagnosticados va en aumento cada día, sobre todo debido a la longevidad creciente de la población y al uso generalizado de las técnicas de imagen que confirman su diagnóstico como la tomografía axial computarizada de alta resolución. Las bronquiectasias son una causa clara de morbimortalidad y suponen una importante carga económica. Los pacientes afectos de bronquiectasias suelen tener exacerbaciones infecciosas que requieren…
Double copies of blaKPC-3::Tn4401a on an IncX3 plasmid in Klebsiella pneumoniae successful clone ST512 from Italy
2015
ABSTRACT A carbapenem-resistant sequence type 512 (ST512) Klebsiella pneumoniae carbapenemase 3 (KPC-3)-producing K. pneumoniae strain showing a novel variant plasmid content was isolated in Palermo, Italy, in 2014. ST512 is a worldwide successful clone associated with the spread of bla KPC genes located on the IncFIIk pKpQIL plasmid. In our ST512 strain, the bla KPC-3 gene was unusually located on an IncX3 plasmid, whose complete sequence was determined. Two copies of bla KPC-3 ::Tn 4401a caused by intramolecular transposition events were detected in the plasmid.