Search results for "Gram-negative"
showing 10 items of 125 documents
The Role of the Classical Pathway for the Bactericidal Effect of Normal Sera Against Gram-Negative Bacteria
1985
Many gram-negative bacteria are killed after treatment with normal serum. This phenomenon was already described in 1889 by Buchner. The serum-bactericidal effect is abolished when serum has been incubated for 30 min at 56° C. Gram-positive bacteria are less sensitive than gram-negative bacteria to direct killing, although gram-positive cocci are opsonized by the action of serum mediated by antibodies and complement (Inoue et al. 1968; Johnston et al. 1969). Normal sera exhibit bactericidal and bacteriolytic properties against some gramnegative strains; whereas, other gram-negative strains are serum resistant. It has been shown that serum from C4-deficient guinea pigs is able to kill some gr…
Interaction of Bacterial Endotoxin (LPS) with Fluid Phase and Macrophage Membrane Associated C1q, the FC-Recognizing Component of the Complement Syst…
1990
The bactericidal activity of normal serum was first described by Buchner in 1889 (10). This effect is abolished when serum has been incubated for 30 min at 56°C. Gram positives are less sensitive than Gram negative bacteria to direct killing, although gram positive cocci are opsonized by the action of serum mediated by antibodies and complement (22). It was found that most of the smooth strains of gram negative bacteria are serum resistant; whereas, the corresponding rough forms are extremely serum sensitive (32, 37). Thus evidence was provided that the composition of the bacterial surface may influence the reaction of the bacteria with the lytic system. The bacteriolytic properties of seru…
ICTV Virus Taxonomy Profile: Cystoviridae
2017
The family Cystoviridae includes enveloped viruses with a tri-segmented dsRNA genome and a double-layered protein capsid. The innermost protein shell is a polymerase complex responsible for genome packaging, replication and transcription. Cystoviruses infect Gram-negative bacteria, primarily plant-pathogenic Pseudomonas syringae strains. This is a summary of the International Committee on Taxonomy of Viruses (ICTV) Report on the taxonomy of the Cystoviridae, which is available at http://www.ictv.global/report/cystoviridae.
Mechanisms of quinolone resistance in Aeromonas species isolated from humans, water and eels.
2009
Mechanisms of resistance were determined in 33 quinolone-resistant isolates of the species Aeromonas hydrophila, Aeromonas caviae, Aeromonas media, Aeromonas salmonicida, Aeromonas popoffii and Aeromonas veronii, recovered from humans, freshwater and eels. The quinolone resistance-determining regions (QRDRs) of gyrA and parC genes were sequenced in these resistant strains, as well as in 8 quinolone-sensitive Aeromonas used as controls. All quinolone-resistant Aeromonas carried point mutations in the gyrA QRDR at codon 83, respectively giving rise to substitutions Ser(83)-->Ile (32 strains) or Ser(83)-->Val (1 strain). Almost half of these isolates (48%) carried additional point mutations in…
Evaluation of the DNA microarray “AMR Direct Flow Chip Kit” for detection of antimicrobial resistance genes from Gram-positive and Gram-negative bact…
2019
Abstract Introduction The AMR Direct Flow Chip assay allows the simultaneous detection of a large variety of antibiotic resistance genetic markers. To assess this kit's performance, we use isolated colonies as starting material. The assay has been approved by the European Economic Area as a suitable device for in vitro diagnosis (CE IVD) using clinical specimens. Methods A total of 210 bacterial isolates harbouring either one or more antimicrobial resistance genes including plasmid-encoded extended-spectrum β-lactamases (SHV, CTX-M) and carbapenemases (GES, SME, KPC, NMC/IMI, SIM, GIM, SPM, NDM, VIM, IMP, and OXA), mecA, vanA and vanB, and 30 controls were included. Results The assay displa…
Detection and organization of atrazine-degrading genetic potential of seventeen bacterial isolates belonging to divergent taxa indicate a recent comm…
2007
A collection of 17 atrazine-degrading bacteria isolated from soils was studied to determine the composition of the atrazine-degrading genetic potential (i.e. trzN, trzD and atz) and the presence of IS1071. The characterization of seven new atrazine-degrading bacteria revealed for the first time the trzN-atzBC gene composition in Gram-negative bacteria such as Sinorhizobium sp. or Polaromonas sp. Three main atrazine-degrading gene combinations (i) trzN– atzBC, (ii) atzABC– trzD and (iii) atzABCDEF were observed. The atz and trz genes were often located on plasmids, suggesting that plasmid conjugation could play an important role in their dispersion. In addition, the observation of these gene…
Diversity of chlorophenol-degrading bacteria isolated from contaminated boreal groundwater
1999
Chlorophenol-degrading bacteria from a long-term polluted groundwater aquifer were characterized. All isolates degraded 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol at concentrations detected in the contaminated groundwater (10 mg 1(-1)). Pentachlorophenol was degraded by three isolates when present alone. In two gram-positive isolates, 2,3,4,6-tetrachlorophenol was required as an inducer for the degradation of pentachlorophenol. The gram-positive isolates were sensitive to pentachlorophenol, with an IC50 value of 5 mg/l. Isolates belonging to the Cytophaga/Flexibacter/Bacteroides phylum had IC50 values of 25 and 63 mg/l. Isolates belonging to alpha-, beta- and gamma-Proteobacteria g…
Pseudomonas corrugata crpCDE is part of the cyclic lipopeptide corpeptin biosynthetic gene cluster and is involved in bacterial virulence in tomato a…
2014
Summary: Pseudomonas corrugataCFBP 5454 produces two kinds of cyclic lipopeptides (CLPs), cormycin A and corpeptins, both of which possess surfactant, antimicrobial and phytotoxic activities. In this study, we identified genes coding for a putative non-ribosomal peptide synthetase and an ABC-type transport system involved in corpeptin production. These genes belong to the same transcriptional unit, designated crpCDE. The genetic organization of this locus is highly similar to other PseudomonasCLP biosynthetic clusters. Matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) analysis revealed that transporter and synthetase genomic knock-out mutants were u…
Coexpression of inducible NO synthase and soluble guanylyl cyclase in colonic enterocytes: a pathophysiologic signaling pathway for the initiation of…
1998
Infectious diarrhea is often caused by the exotoxins of gram-negative bacteria such as Escherichia coli. However, these organisms also contain lipopolysaccharide (LPS) endotoxin. LPS induces nitric oxide synthase II (NOS II, inducible NOS) in various types of cells. We now demonstrate by RNase protection analysis, Western blot, and immunohistochemistry that the expression of NOS II mRNA and protein is markedly induced in colonic enterocytes of mice that ingest LPS with their drinking water. Using the same techniques, significant levels of soluble guanylyl cyclase (GC-S), the effector enzyme of NO, were found constitutively expressed in the mucosa. This creates a pathophysiologic autocrine p…
Antibacterial studies, DNA oxidative cleavage, and crystal structures of Cu(II) and Co(II) complexes with two quinolone family members, ciprofloxacin…
2005
Nine coordination compounds of Cu(II) and Co(II) with Ciprofloxacin (HCp) and Enoxacin (HEx) as ligands have been prepared and characterized. Single crystal structural determinations of [Cu(HCp)2(ClO4)2].6H2O (1) and [Co(HEx)2(Ex)]Cl.2CH(3)OH.12H2O (4) are reported. The crystal of 1 is composed of [Cu(HCp)2(ClO4)2] units with the two perchlorate anions semicoordinated, and uncoordinated water molecules. The copper ion, at a crystallographic inversion centre, is in a tetragonally distorted octahedral environment. The structure of 4 consists of cationic monomeric [Co(HEx)2(Ex)]+ units, chloride anions, and uncoordinated methanol and water molecules. The complex is six-coordinate, with a sligh…