Gram-Negative Bacteria: Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method.Gram-Positive Bacteria: Bacteria which retain the crystal violet stain when treated by Gram's method.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Gram-Negative Bacterial Infections: Infections caused by bacteria that show up as pink (negative) when treated by the gram-staining method.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Microbial Sensitivity Tests: Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).Anti-Infective Agents: Substances that prevent infectious agents or organisms from spreading or kill infectious agents in order to prevent the spread of infection.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Pseudomonadaceae: A family of gram-negative bacteria usually found in soil or water and including many plant pathogens and a few animal pathogens.Bacterial Proteins: Proteins found in any species of bacterium.Lipopolysaccharides: Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: LIPID A, core polysaccharide, and O-specific chains (O ANTIGENS). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal B-cell mitogens commonly used in laboratory immunology. (From Dorland, 28th ed)Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Bacterial Infections: Infections by bacteria, general or unspecified.Pseudomonas aeruginosa: A species of gram-negative, aerobic, rod-shaped bacteria commonly isolated from clinical specimens (wound, burn, and urinary tract infections). It is also found widely distributed in soil and water. P. aeruginosa is a major agent of nosocomial infection.Staphylococcus aureus: Potentially pathogenic bacteria found in nasal membranes, skin, hair follicles, and perineum of warm-blooded animals. They may cause a wide range of infections and intoxications.Antimicrobial Cationic Peptides: Small cationic peptides that are an important component, in most species, of early innate and induced defenses against invading microbes. In animals they are found on mucosal surfaces, within phagocytic granules, and on the surface of the body. They are also found in insects and plants. Among others, this group includes the DEFENSINS, protegrins, tachyplesins, and thionins. They displace DIVALENT CATIONS from phosphate groups of MEMBRANE LIPIDS leading to disruption of the membrane.Bacteria, AnaerobicGram-Negative Aerobic Bacteria: A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. This is because the cell walls of gram-negative bacteria are low in peptidoglycan and thus have low affinity for violet stain and high affinity for the pink dye safranine.Gram-Negative Anaerobic Bacteria: A large group of anaerobic bacteria which show up as pink (negative) when treated by the Gram-staining method.Fermentation: Anaerobic degradation of GLUCOSE or other organic nutrients to gain energy in the form of ATP. End products vary depending on organisms, substrates, and enzymatic pathways. Common fermentation products include ETHANOL and LACTIC ACID.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Bacteriological Techniques: Techniques used in studying bacteria.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.Phytochemicals: A broad range of biologically active compounds which occur naturally in plants having important medicinal and nutritional properties.Bacteremia: The presence of viable bacteria circulating in the blood. Fever, chills, tachycardia, and tachypnea are common acute manifestations of bacteremia. The majority of cases are seen in already hospitalized patients, most of whom have underlying diseases or procedures which render their bloodstreams susceptible to invasion.Enterobacteriaceae: A family of gram-negative, facultatively anaerobic, rod-shaped bacteria that do not form endospores. Its organisms are distributed worldwide with some being saprophytes and others being plant and animal parasites. Many species are of considerable economic importance due to their pathogenic effects on agriculture and livestock.Magnetic Resonance Spectroscopy: Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Water Microbiology: The presence of bacteria, viruses, and fungi in water. This term is not restricted to pathogenic organisms.Fungi: A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including MUSHROOMS; YEASTS; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies.Gram-Positive Bacterial Infections: Infections caused by bacteria that retain the crystal violet stain (positive) when treated by the gram-staining method.Colony Count, Microbial: Enumeration by direct count of viable, isolated bacterial, archaeal, or fungal CELLS or SPORES capable of growth on solid CULTURE MEDIA. The method is used routinely by environmental microbiologists for quantifying organisms in AIR; FOOD; and WATER; by clinicians for measuring patients' microbial load; and in antimicrobial drug testing.Sepsis: Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by HYPOTENSION despite adequate fluid infusion, it is called SEPTIC SHOCK.Klebsiella Infections: Infections with bacteria of the genus KLEBSIELLA.Gangrene: Death and putrefaction of tissue usually due to a loss of blood supply.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Bacteria, AerobicSequence Analysis, DNA: A multistage process that includes cloning, physical mapping, subcloning, determination of the DNA SEQUENCE, and information analysis.Gentian Violet: A dye that is a mixture of violet rosanilinis with antibacterial, antifungal, and anthelmintic properties.Eye Infections, Bacterial: Infections in the inner or external eye caused by microorganisms belonging to several families of bacteria. Some of the more common genera found are Haemophilus, Neisseria, Staphylococcus, Streptococcus, and Chlamydia.Limulus Test: Sensitive method for detection of bacterial endotoxins and endotoxin-like substances that depends on the in vitro gelation of Limulus amebocyte lysate (LAL), prepared from the circulating blood (amebocytes) of the horseshoe crab, by the endotoxin or related compound. Used for detection of endotoxin in body fluids and parenteral pharmaceuticals.Klebsiella pneumoniae: Gram-negative, non-motile, capsulated, gas-producing rods found widely in nature and associated with urinary and respiratory infections in humans.Genes, Bacterial: The functional hereditary units of BACTERIA.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.PhenazinesDNA, Ribosomal: DNA sequences encoding RIBOSOMAL RNA and the segments of DNA separating the individual ribosomal RNA genes, referred to as RIBOSOMAL SPACER DNA.Wound Infection: Invasion of the site of trauma by pathogenic microorganisms.Endotoxins: Toxins closely associated with the living cytoplasm or cell wall of certain microorganisms, which do not readily diffuse into the culture medium, but are released upon lysis of the cells.Pseudomonas Infections: Infections with bacteria of the genus PSEUDOMONAS.IndiaDrug Resistance, Multiple, Bacterial: The ability of bacteria to resist or to become tolerant to several structurally and functionally distinct drugs simultaneously. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Drug Resistance, Bacterial: The ability of bacteria to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Cross Infection: Any infection which a patient contracts in a health-care institution.Peritonitis: INFLAMMATION of the PERITONEUM lining the ABDOMINAL CAVITY as the result of infectious, autoimmune, or chemical processes. Primary peritonitis is due to infection of the PERITONEAL CAVITY via hematogenous or lymphatic spread and without intra-abdominal source. Secondary peritonitis arises from the ABDOMINAL CAVITY itself through RUPTURE or ABSCESS of intra-abdominal organs.Abdominal Muscles: Muscles forming the ABDOMINAL WALL including RECTUS ABDOMINIS, external and internal oblique muscles, transversus abdominis, and quadratus abdominis. (from Stedman, 25th ed)Pneumonia, Bacterial: Inflammation of the lung parenchyma that is caused by bacterial infections.Infant, Newborn: An infant during the first month after birth.Fever: An abnormal elevation of body temperature, usually as a result of a pathologic process.Intestines: The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.Soil Microbiology: The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.beta-Lactamases: Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.Bacterial Physiological Phenomena: Physiological processes and properties of BACTERIA.Escherichia coli Infections: Infections with bacteria of the species ESCHERICHIA COLI.Drug Resistance, Microbial: The ability of microorganisms, especially bacteria, to resist or to become tolerant to chemotherapeutic agents, antimicrobial agents, or antibiotics. This resistance may be acquired through gene mutation or foreign DNA in transmissible plasmids (R FACTORS).Time Factors: Elements of limited time intervals, contributing to particular results or situations.Pneumonia: Infection of the lung often accompanied by inflammation.RNA, Bacterial: Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.Toll-Like Receptor 4: A pattern recognition receptor that interacts with LYMPHOCYTE ANTIGEN 96 and LIPOPOLYSACCHARIDES. It mediates cellular responses to GRAM-NEGATIVE BACTERIA.Sulfur-Reducing Bacteria: A group of gram-negative, anaerobic bacteria that is able to oxidize acetate completely to carbon dioxide using elemental sulfur as the electron acceptor.Seawater: The salinated water of OCEANS AND SEAS that provides habitat for marine organisms.Staphylococcal Infections: Infections with bacteria of the genus STAPHYLOCOCCUS.Molecular Structure: The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.

In vivo activities of peptidic prodrugs of novel aminomethyl tetrahydrofuranyl-1 beta-methylcarbapenems. (1/3518)

A series of novel aminomethyl tetrahydrofuranyl (THF)-1 beta-methylcarbapenems which have excellent broad-spectrum antibacterial activities exhibit modest efficacies against acute lethal infections (3.8 mg/kg of body weight against Escherichia coli and 0.9 mg/kg against Staphylococcus aureus) in mice when they are administered orally. In an effort to improve the efficacies of orally administered drugs through enhanced absorption by making use of a peptide-mediated transport system, several different amino acids were added at the aminomethyl THF side chains of the carbapenem molecules. The resulting peptidic prodrugs with L-amino acids demonstrated improved efficacy after oral administration, while the D forms were less active than the parent molecules. After oral administration increased (3 to 10 times) efficacy was exhibited with the alanine-, valine-, isoleucine-, and phenylalanine-substituted prodrugs against acute lethal infections in mice. Median effective doses (ED50s) of < 1 mg/kg against infections caused by S. aureus, E. coli, Enterobacter cloacae, or penicillin-susceptible Streptococcus pneumoniae were obtained after the administration of single oral doses. Several of the peptidic prodrugs were efficacious against Morganella morganii, Serratia marcescens, penicillin-resistant S. pneumoniae, extended-spectrum beta-lactamase-producing Klebsiella pneumoniae, and E. coli infections, with ED50s of 1 to 14 mg/kg by oral administration compared with ED50s of 14 to > 32 mg/kg for the parent molecules. In general, the parent molecules demonstrated greater efficacy than the prodrugs against these same infections when the drugs were administered by the subcutaneous route. The parent molecule was detectable in the sera of mice after oral administration of the peptidic prodrugs.  (+info)

Identification of a novel group of bacteria in sludge from a deteriorated biological phosphorus removal reactor. (2/3518)

The microbial diversity of a deteriorated biological phosphorus removal reactor was investigated by methods not requiring direct cultivation. The reactor was fed with media containing acetate and high levels of phosphate (P/C weight ratio, 8:100) but failed to completely remove phosphate in the effluent and showed very limited biological phosphorus removal activity. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S ribosomal DNA was used to investigate the bacterial diversity. Up to 11 DGGE bands representing at least 11 different sequence types were observed; DNA from the 6 most dominant of these bands was further isolated and sequenced. Comparative phylogenetic analysis of the partial 16S rRNA sequences suggested that one sequence type was affiliated with the alpha subclass of the Proteobacteria, one was associated with the Legionella group of the gamma subclass of the Proteobacteria, and the remaining four formed a novel group of the gamma subclass of the Proteobacteria with no close relationship to any previously described species. The novel group represented approximately 75% of the PCR-amplified DNA, based on the DGGE band intensities. Two oligonucleotide rRNA probes for this novel group were designed and used in a whole-cell hybridization analysis to investigate the abundance of this novel group in situ. The bacteria were coccoid and 3 to 4 microm in diameter and represented approximately 35% of the total population, suggesting a relatively close agreement with the results obtained by the PCR-based DGGE method. Further, based on electron microscopy and standard staining microscopic analysis, this novel group was able to accumulate granule inclusions, possibly consisting of polyhydroxyalkanoate, inside the cells.  (+info)

Pulsed-light inactivation of food-related microorganisms. (3/3518)

The effects of high-intensity pulsed-light emissions of high or low UV content on the survival of predetermined populations of Listeria monocytogenes, Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, Bacillus cereus, and Staphylococcus aureus were investigated. Bacterial cultures were seeded separately on the surface of tryptone soya-yeast extract agar and were reduced by up to 2 or 6 log10 orders with 200 light pulses (pulse duration, approximately 100 ns) of low or high UV content, respectively (P < 0.001).  (+info)

Class I integrons in Gram-negative isolates from different European hospitals and association with decreased susceptibility to multiple antibiotic compounds. (4/3518)

Class I integrons are associated with carriage of genes encoding resistance to antibiotics. Expression of inserted resistance genes within these structures can be poor and, as such, the clinical relevance in terms of the effect of integron carriage on susceptibility has not been investigated. Of 163 unrelated Gram-negative isolates randomly selected from the intensive care and surgical units of 14 different hospitals in nine European countries, 43.0% (70/163) of isolates were shown to be integron-positive, with inserted gene cassettes of various sizes. Integrons were detected in isolates from all hospitals with no particular geographical variations. Integron-positive isolates were statistically more likely to be resistant to aminoglycoside, quinolone and beta8-lactam compounds, including third-generation cephalosporins and monobactams, than integron-negative isolates. Integron-positive isolates were also more likely to be multi-resistant than integron-negative isolates. This association implicates integrons in multi-drug resistance either directly through carriage of specific resistance genes, or indirectly by virtue of linkage to other resistance determinants such as extended-spectrum beta-lactamase genes. As such their widespread presence is a cause for concern. There was no association between the presence of integrons and susceptibility to cefepime, amikacin and the carbapenems, to which at least 97% of isolates were fully susceptible.  (+info)

Killing kinetics of intracellular Afipia felis treated with amikacin. (5/3518)

Afipia felis is a facultative intracellular bacterium which multiplies in macrophages following inhibition of phagosome-lysosome (P-L) fusion. When A. felis-infected cells are incubated for 72 h with various antibiotics, only aminoglycosides are found to be bactericidal. We therefore studied the killing of intracellular A. felis by amikacin, and its relationship with the restoration of P-L fusion. Amikacin reduced the number of A. felis from 8.5 x 10(5) to 3.5 x 102 cfu/mL within 94 h. P-L fusion was restored after 30-40 h of incubation with amikacin. Both mechanisms may participate in the intracellular killing of bacteria.  (+info)

A GroEL homologue from endosymbiotic bacteria of the whitefly Bemisia tabaci is implicated in the circulative transmission of tomato yellow leaf curl virus. (6/3518)

Evidence for the involvement of a Bemisia tabaci GroEL homologue in the transmission of tomato yellow leaf curl geminivirus (TYLCV) is presented. A approximately 63-kDa protein was identified in B. tabaci whole-body extracts using an antiserum raised against aphid Buchnera GroEL. The GroEL homologue was immunolocalized to a coccoid-shaped whitefly endosymbiont. The 30 N-terminal amino acids of the whitefly GroEL homologue showed 80% homology with that from different aphid species and GroEL from Escherichia coli. Purified GroEL from B. tabaci exhibited ultrastructural similarities to that of the endosymbiont from aphids and E. coli. In vitro ligand assays showed that tomato yellow leaf curl virus (TYLCV) particles displayed a specific affinity for the B. tabaci 63-kDa GroEL homologue. Feeding whiteflies anti-Buchnera GroEL antiserum before the acquisition of virions reduced TYLCV transmission to tomato test plants by >80%. In the haemolymph of these whiteflies, TYLCV DNA was reduced to amounts below the threshold of detection by Southern blot hybridization. Active antibodies were recovered from the insect haemolymph suggesting that by complexing the GoEL homologue, the antibody disturbed interaction with TYLCV, leading to degradation of the virus. We propose that GroEL of B. tabaci protects the virus from destruction during its passage through the haemolymph.  (+info)

Molecular analysis of a novel methanesulfonic acid monooxygenase from the methylotroph Methylosulfonomonas methylovora. (7/3518)

Methylosulfonomonas methylovora M2 is an unusual gram-negative methylotrophic bacterium that can grow on methanesulfonic acid (MSA) as the sole source of carbon and energy. Oxidation of MSA by this bacterium is carried out by a multicomponent MSA monooxygenase (MSAMO). Cloning and sequencing of a 7.5-kbp SphI fragment of chromosomal DNA revealed four tightly linked genes encoding this novel monooxygenase. Analysis of the deduced MSAMO polypeptide sequences indicated that the enzyme contains a two-component hydroxylase of the mononuclear-iron-center type. The large subunit of the hydroxylase, MsmA (48 kDa), contains a typical Rieske-type [2Fe-2S] center with an unusual iron-binding motif and, together with the small subunit of the hydroxylase, MsmB (20 kDa), showed a high degree of identity with a number of dioxygenase enzymes. However, the other components of the MSAMO, MsmC, the ferredoxin component, and MsmD, the reductase, more closely resemble those found in other classes of oxygenases. MsmC has a high degree of identity to ferredoxins from toluene and methane monooxygenases, which are enzymes characterized by possessing hydroxylases containing mu-oxo bridge binuclear iron centers. MsmD is a reductase of 38 kDa with a typical chloroplast-like [2Fe-2S] center and conserved flavin adenine dinucleotide- and NAD-binding motifs and is similar to a number of mono- and dioxygenase reductase components. Preliminary analysis of the genes encoding MSAMO from a marine MSA-degrading bacterium, Marinosulfonomonas methylotropha, revealed the presence of msm genes highly related to those found in Methylosulfonomonas, suggesting that MSAMO is a novel type of oxygenase that may be conserved in all MSA-utilizing bacteria.  (+info)

Lipopolyamines: novel antiendotoxin compounds that reduce mortality in experimental sepsis caused by gram-negative bacteria. (8/3518)

The interactions of lipopolyamines, a class of structurally unique compounds currently being used as transfection (lipofection) agents, with lipopolysaccharide (LPS) have been characterized. Our studies have demonstrated that 1,3-di-oleoyloxy-2-(6-carboxyspermyl)-propylamide), available commercially as DOSPER, binds to purified LPS with an affinity of about 1/10 that of polymyxin B. This essentially nontoxic compound inhibits, in a dose-dependent manner, LPS-induced activation of the Limulus clotting cascade and the production of tumor necrosis factor alpha (TNF-alpha) interleukin-6 (IL-6), and nitric oxide from LPS-stimulated J774.A1 cells, a murine macrophage-like cell line. Cytokine inhibition is paralleled by decreased steady-state levels of TNF-alpha and IL-6 mRNA and inhibits the nuclear translocation of nuclear factor kappa B. These findings suggest that the lipopolyamine compound sequesters LPS, thereby blocking downstream cellular activation events that lead to the production of proinflammatory mediators. Administration of DOSPER to D-galactosamine-sensitized mice challenged either with LPS or with Escherichia coli organisms provided significant protection against lethality both with and without antibiotic chemotherapy. Partial protection is evident in LPS-challenged mice treated with DOSPER as late as 2 to 4 h following the endotoxin challenge. A greater degree of protection is observed in E. coli-challenged animals receiving ceftazidime than in those receiving imipenem, which is probably attributable to the higher levels of LPS released in vivo by the former antibiotic. Potent antiendotoxic activity, low toxicity, and ease of synthesis render the lipopolyamines candidate endotoxin-sequestering agents of potential significant therapeutic value.  (+info)

  • Bacteria employ a variety of strategies to sequester iron from the environment and to store intracellular iron surplus that can be utilized in iron-restricted conditions while also limiting the potential for the production of iron-induced reactive oxygen species (ROS). (
  • Prior to evaluate the efficacy of the scaffolds against gram positive and gram negative bacterial strains, the scaffolds were characterized for the presence of the Ag NPs with field emission scanning electron microscope (FE-SEM), fourier transform infrared (FTIR) spectroscopy and x-ray diffractometer (XRD). (
  • Each demonstrated good potency against these bacteria, with the majority of MICs less than or equal to 2 micrograms/mL, including against strains that have been constitutively methylated and dimethylated. (
  • Taking into account the clinical severity that may be associated with CAP caused by Gram-negative bacteria (respiratory failure, bacteremia, shock, acute respiratory distress syndrome [ARDS]) the magnitude of the global health problem is tremendous. (
  • Macrolides, such as azithromycin, erythromycin and clarithromycin, inhibit protein synthesis in bacteria by binding to a site on the bacterial ribosome. (
  • Although several different bacteria and respiratory viruses can be responsible for CAP, Streptococcus pneumoniae (pneumococcus) remains the most common causative pathogen. (