bluuebunny/crossref_metadata_2025_split huggingface dataset:
ColE1-Like Plasmid pIP843 of
Klebsiella pneumoniae
Encoding Extended-Spectrum β-Lactamase CTX-M-17
Authors: Cao Van , Lambert Thierry , Courvalin Patrice 
Published: July 2002

ABSTRACT

The resistance of
Klebsiella pneumoniae
BM4493, isolated in Ho Chi Minh City, Vietnam, to cefotaxime and aztreonam was due to production of a novel β-lactamase, CTX-M-17. The
bla
CTX-M-17
gene was borne by 7,086-bp plasmid pIP843, which was entirely sequenced and which was found to belong to the ColE1 family. The 876-bp
bla
CTX-M-17
gene differed from
bla
CTX-M-14
by 2 nucleotides, which led to the single amino acid substitution Glu289→Lys.
bla
CTX-M-17
was flanked upstream by an IS
Ecp1
-like element and downstream by an insertion sequence (IS) IS
903
variant designated IS
903
-C. The transcriptional start site of
bla
CTX-M-17
was located 109 nucleotides upstream from the initiation codon in the IS
Ecp1-
like element, which also provided the promoter sequences. Plasmid pIP843, which was non-self-transferable and nonmobilizable, contained five open reading frames transcribed in the same orientation. Regions homologous to sequences coding for putative RNA II and RNA I transcripts, a
rom
gene, which is involved in initiation of replication, and a
cer
-like gene, which is responsible for the stability of ColE1-like plasmids, were identified. Consensus sequences for putative replication (
oriV
) and transfer (
oriT
) origins were present. Results of primer extension experiments indicated that IS
Ecp1
provides the promoter for expression of
bla
CTX-M-17
and may contribute to dissemination of this gene.
Effect of Telithromycin (HMR 3647) on Polymorphonuclear Neutrophil Killing ofStaphylococcus aureusin Comparison with Roxithromycin
Authors: Vazifeh D. , Abdelghaffar H. , Labro M. T. 
Published: July 2002

ABSTRACTHMR 3647 (telithromycin), a new ketolide, is active on intracellular pathogens. It was previously demonstrated that it inhibits superoxide anion production in a time- and concentration-dependent manner, at concentrations which inhibit 50% of the control response of about 55 μg/ml (5 min) to 30 μg/ml (30 min); these values are similar to those obtained with roxithromycin, a classical erythromycin A derivative. Here we investigated whether these drugs modified the bactericidal activity of human polymorphonuclear neutrophils (PMN) on four strains ofStaphylococcus aureuswith different profiles of susceptibility to macrolides and ketolides. We found that the main factor involved in killing was the antibacterial potency of the drugs, although combinations of antibiotics with PMN were slightly more active than each component used alone against two of the four strains. In addition, high concentrations of the drugs, which impaired the PMN oxidative burst, did not impair PMN bactericidal activity. Likewise, some cytokines which enhance PMN oxidative metabolism did not modify PMN bactericidal activity in the presence or absence of macrolides or ketolides. These data suggest that oxygen-independent mechanisms contribute to the bactericidal activity of PMN on these strains ofS. aureus. Both live and/or heat-killed bacteria impaired the uptake of telithromycin and roxithromycin (but not that of levofloxacin, a quinolone) in a concentration-dependent manner, owing to a modulation of PMN transductional systems involved in the activation of the macrolide carrier.
DPC 817: a Cytidine Nucleoside Analog with Activity against Zidovudine- and Lamivudine-Resistant Viral Variants
Authors: Schinazi Raymond F. , Mellors John , Bazmi Holly , Diamond Sharon , Garber Sena , Gallagher Karen , Geleziunas Romas , Klabe Ron , Pierce Michael , Rayner Marlene , Wu Jing-Tao , Zhang Hangchun , Hammond Jennifer , Bacheler Lee , Manion Douglas J. , Otto Michael J. , Stuyver Lieven , Trainor George , Liotta Dennis C. , Erickson-Viitanen Susan 
Published: July 2002

ABSTRACT
Highly active antiretroviral therapy (HAART) is the standard treatment for infection with the human immunodeficiency virus (HIV). HAART regimens consist of protease inhibitors or nonnucleoside reverse transcriptase inhibitors combined with two or more nucleoside reverse transcriptase inhibitors (NRTIs). DPC 817, 2′,3′-didehydro-2′,3′-dideoxy-5-fluorocytidine (PSI 5582 D-D4FC) is a potent inhibitor of HIV type 1 replication in vitro. Importantly, DPC 817 retains activity against isolates harboring mutations in the reverse transcriptase gene that confer resistance to lamivudine (3TC) and zidovudine (AZT), which are frequent components of initial HAART regimens. DPC 817 combines this favorable resistance profile with rapid uptake and conversion to the active metabolite DPC 817-triphosphate, which has an intracellular half-life of 13 to 17 h. Pharmacokinetics in the rhesus monkey suggest low clearance of parent DPC 817 and a plasma half-life longer than that of either AZT or 3TC. Together, these properties suggest that DPC 817 may be useful as a component of HAART regimens in individuals with resistance to older NRTI agents.
Reassessment of
Clostridium difficile
Susceptibility to Metronidazole and Vancomycin
Authors: Peláez T. , Alcalá L. , Alonso R. , Rodríguez-Créixems M. , García-Lechuz J. M. , Bouza E. 
Published: July 2002

ABSTRACT

Clostridium difficile
is the most frequently identified enteric pathogen in patients with nosocomially acquired, antibiotic-associated diarrhea. The drugs most commonly used to treat diseases associated with
C. difficile
are metronidazole and vancomycin. Most clinical laboratories assume that all
C. difficile
isolates are susceptible to metronidazole and vancomycin. We report on the antimicrobial susceptibilities of 415
C. difficile
isolates to metronidazole and vancomycin over an 8-year period (1993 to 2000). The overall rate of resistance to metronidazole at the critical breakpoint (16 μg/ml) was 6.3%. Although full resistance to vancomycin was not observed, the overall rate of intermediate resistance was 3.1%. One isolate had a combination of resistance to metronidazole and intermediate resistance to vancomycin. Rates of resistance to metronidazole and vancomycin were higher among isolates from human immunodeficiency virus-infected patients. Molecular typing methods proved the absence of clonality among the isolates with decreased susceptibilities to the antimicrobials tested.
Reduction of Fe(III), Mn(IV), and Toxic Metals at 100°C by
Pyrobaculum islandicum
Authors: Kashefi Kazem , Lovley Derek R. 
Published: July 2002

ABSTRACT

It has recently been noted that a diversity of hyperthermophilic microorganisms have the ability to reduce Fe(III) with hydrogen as the electron donor, but the reduction of Fe(III) or other metals by these organisms has not been previously examined in detail. When
Pyrobaculum islandicum
was grown at 100°C in a medium with hydrogen as the electron donor and Fe(III)-citrate as the electron acceptor, the increase in cell numbers of
P. islandicum
per mole of Fe(III) reduced was found to be ca. 10-fold higher than previously reported. Poorly crystalline Fe(III) oxide could also serve as the electron acceptor for growth on hydrogen. The stoichiometry of hydrogen uptake and Fe(III) oxide reduction was consistent with the oxidation of 1 mol of hydrogen resulting in the reduction of 2 mol of Fe(III). The poorly crystalline Fe(III) oxide was reduced to extracellular magnetite.
P. islandicum
could not effectively reduce the crystalline Fe(III) oxide minerals goethite and hematite. In addition to using hydrogen as an electron donor for Fe(III) reduction,
P. islandicum
grew via Fe(III) reduction in media in which peptone and yeast extract served as potential electron donors. The closely related species
P. aerophilum
grew via Fe(III) reduction in a similar complex medium. Cell suspensions of
P. islandicum
reduced the following metals with hydrogen as the electron donor: U(VI), Tc(VII), Cr(VI), Co(III), and Mn(IV). The reduction of these metals was dependent upon the presence of cells and hydrogen. The metalloids arsenate and selenate were not reduced. U(VI) was reduced to the insoluble U(IV) mineral uraninite, which was extracellular. Tc(VII) was reduced to insoluble Tc(IV) or Tc(V). Cr(VI) was reduced to the less toxic, less soluble Cr(III). Co(III) was reduced to Co(II). Mn(IV) was reduced to Mn(II) with the formation of manganese carbonate. These results demonstrate that biological reduction may contribute to the speciation of metals in hydrothermal environments and could account for such phenomena as magnetite accumulation and the formation of uranium deposits at ca. 100°C. Reduction of toxic metals with hyperthermophilic microorganisms or their enzymes might be applied to the remediation of metal-contaminated waters or waste streams.
Engineering Desiccation Tolerance in
Escherichia coli
Authors: Billi Daniela , Wright Deborah J. , Helm Richard F. , Prickett Todd , Potts Malcolm , Crowe John H. 
Published: July 2002

ABSTRACT

Recombinant sucrose-6-phosphate synthase (SpsA) was synthesized in
Escherichia coli
BL21DE3 by using the
spsA
gene of the cyanobacterium
Synechocystis
sp. strain PCC 6803. Transformants exhibited a 10,000-fold increase in survival compared to wild-type cells following either freeze-drying, air drying, or desiccation over phosphorus pentoxide. The phase transition temperatures and vibration frequencies (PO stretch) in phospholipids suggested that sucrose maintained membrane fluidity during cell dehydration.
An In Vitro Study of the Effect of Fluoridated Milk on Oral Bacterial Biofilms
Authors: Pratten J. , Bedi R. , Wilson M. 
Published: July 2002

ABSTRACT
Microcosmic dental plaques were grown in artificial saliva and supplemented with either milk or fluoridated milk. The presence of fluoride in the milk increased the pH of the biofilms and reduced the proportions of streptococci, demonstrating that in this model, fluoridation of milk produces biofilms with reduced cariogenic potential.
A Few Cosmopolitan Phylotypes Dominate Planktonic Archaeal Assemblages in Widely Different Oceanic Provinces
Authors: Massana Ramon , DeLong Edward F. , Pedrós-Alió Carlos 
Published: July 2002

ABSTRACT
We compared the phylogenetic compositions of marine planktonic archaeal populations in different marine provinces. Samples from eight different environments were collected at two depths (surface and aphotic zone), and 16 genetic libraries of PCR-amplified archaeal 16S rRNA genes were constructed. The libraries were analyzed by using a three-step hierarchical approach. Membrane hybridization experiments revealed that most of the archaeal clones were affiliated with one of the two groups of marine archaea described previously, crenarchaeotal group I and euryarchaeotal group II. One of the 2,328 ribosomal DNA clones analyzed was related to a different euryarchaeal lineage, which was recently recovered from deep-water marine plankton. In temperate regions (Pacific Ocean, Atlantic Ocean, and Mediterranean Sea) both major groups were found at the two depths investigated; group II predominated at the surface, and group I predominated at depth. In Antarctic and subantarctic waters group II was practically absent. The clonal compositions of archaeal libraries were investigated by performing a restriction fragment length polymorphism (RFLP) analysis with two tetrameric restriction enzymes, which defined discrete operational taxonomic units (OTUs). The OTUs defined in this way were phylogenetically consistent; clones belonging to the same OTU were closely related. The clonal diversity as determined by the RFLP analysis was low, and most libraries were dominated by only one or two OTUs. Some OTUs were found in samples obtained from very distant places, indicating that some phylotypes were ubiquitous. A tree containing one example of each OTU detected was constructed, and this tree revealed that there were several clusters within archaeal group I and group II. The members of some of these clusters had different depth distributions.
A
Mycobacterium
Strain with Extended Capacities for Degradation of Gasoline Hydrocarbons
Authors: Solano-Serena Floriane , Marchal Rémy , Casarégola Serge , Vasnier Christelle , Lebeault Jean-Michel , Vandecasteele Jean-Paul 
Published: July 2002

ABSTRACT

A bacterial strain (strain IFP 2173) was selected from a gasoline-polluted aquifer on the basis of its capacity to use 2,2,4-trimethylpentane (isooctane) as a sole carbon and energy source. This isolate, the first isolate with this capacity to be characterized, was identified by 16S ribosomal DNA analysis, and 100% sequence identity with a reference strain of
Mycobacterium austroafricanum
was found.
Mycobacterium
sp. strain IFP 2173 used an unusually wide spectrum of hydrocarbons as growth substrates, including
n
-alkanes and multimethyl-substituted isoalkanes with chains ranging from 5 to 16 carbon atoms long, as well as substituted monoaromatic hydrocarbons. It also attacked ethers, such as methyl
t
-butyl ether. During growth on gasoline, it degraded 86% of the substrate. Our results indicated that strain IFP 2173 was capable of degrading 3-methyl groups, possibly by a carboxylation and deacetylation mechanism. Evidence that it attacked the quaternary carbon atom structure by an as-yet-undefined mechanism during growth on 2,2,4-trimethylpentane and 2,2-dimethylpentane was also obtained.
Cloning, Expression, and Sequence Analysis of the Gene Encoding the Alkali-Stable, Thermostable Endoxylanase from Alkalophilic, Mesophilic
Bacillus
sp. Strain NG-27
Authors: Gupta Naveen , Reddy Vanga Shiva , Maiti Sankar , Ghosh Amit 
Published: July 2002

ABSTRACT

Alkalophilic
Bacillus
sp. strain NG-27 produces a 42-kDa endoxylanase active at 70°C and at a pH of 8.4. The gene for this endoxylanase was cloned and sequenced. The gene contained one open reading frame of 1,215 bases. An active site characteristic of the family 10 β-glycanases was recognized between amino acids 303 and 313, with the active glutamate at position 310. Though highly thermostable, the enzyme contains no cysteine residue.
Effect of Starvation and the Viable-but-Nonculturable State on Green Fluorescent Protein (GFP) Fluorescence in GFP-Tagged
Pseudomonas fluorescens
A506
Authors: Lowder M. , Unge A. , Maraha N. , Jansson J. K. , Swiggett J. , Oliver J. D. 
Published: July 2002

ABSTRACT

The green fluorescent protein (GFP) gene,
gfp
, of the jellyfish
Aequorea victoria
is being used as a reporter system for gene expression and as a marker for tracking prokaryotes and eukaryotes. Cells that have been genetically altered with the
gfp
gene produce a protein that fluoresces when it is excited by UV light. This unique phenotype allows
gfp
-tagged cells to be specifically monitored by nondestructive means. In this study we determined whether a
gfp
-tagged strain of
Pseudomonas fluorescens
continued to fluoresce under conditions under which the cells were starved, viable but nonculturable (VBNC), or dead. Epifluorescent microscopy, flow cytometry, and spectrofluorometry were used to measure fluorescence intensity in starved, VBNC, and dead or dying cells. Results obtained by using flow cytometry indicated that microcosms containing VBNC cells, which were obtained by incubation under stress conditions (starvation at 37.5°C), fluoresced at an intensity that was at least 80% of the intensity of nonstressed cultures. Similarly, microcosms containing starved cells incubated at 5 and 30°C had fluorescence intensities that were 90 to 110% of the intensity of nonstressed cells. VBNC cells remained fluorescent during the entire 6-month incubation period. In addition, cells starved at 5 or 30°C remained fluorescent for at least 11 months. Treatment of the cells with UV light or incubation at 39 or 50°C resulted in a loss of GFP from the cells. There was a strong correlation between cell death and leakage of GFP from the cells, although the extent of leakage varied depending on the treatment. Most dead cells were not GFP fluorescent, but a small proportion of the dead cells retained some GFP at a lower concentration than the concentration in live cells. Our results suggest that
gfp
-tagged cells remain fluorescent following starvation and entry into the VBNC state but that fluorescence is lost when the cells die, presumably because membrane integrity is lost.
Anhydrobiotic Engineering of Gram-Negative Bacteria
Authors: García de Castro Arcadio , Bredholt Harald , Strøm Arne R. , Tunnacliffe Alan 
Published: July 2002

ABSTRACT

Anhydrobiotic engineering aims to improve desiccation tolerance in living organisms by adopting the strategies of anhydrobiosis. This was achieved for
Escherichia coli
and
Pseudomonas putida
by osmotic induction of intracellular trehalose synthesis and by drying from trehalose solutions, resulting in long-term viability in the dried state.
Inactivation of Gram-Negative Bacteria by Lysozyme, Denatured Lysozyme, and Lysozyme-Derived Peptides under High Hydrostatic Pressure
Authors: Masschalck Barbara , Van Houdt Rob , Van Haver Ellen G. R. , Michiels Chris W. 
Published: July 2002

ABSTRACT

We have studied the inactivation of six gram-negative bacteria (
Escherichia coli
,
Pseudomonas fluorescens
,
Salmonella enterica
serovar Typhimurium,
Salmonella enteritidis
,
Shigella sonnei
, and
Shigella flexneri
) by high hydrostatic pressure treatment in the presence of hen egg-white lysozyme, partially or completely denatured lysozyme, or a synthetic cationic peptide derived from either hen egg white or coliphage T4 lysozyme. None of these compounds had a bactericidal or bacteriostatic effect on any of the tested bacteria at atmospheric pressure. Under high pressure, all bacteria except both
Salmonella
species showed higher inactivation in the presence of 100 μg of lysozyme/ml than without this additive, indicating that pressure sensitized the bacteria to lysozyme. This extra inactivation by lysozyme was accompanied by the formation of spheroplasts. Complete knockout of the muramidase enzymatic activity of lysozyme by heat treatment fully eliminated its bactericidal effect under pressure, but partially denatured lysozyme was still active against some bacteria. Contrary to some recent reports, these results indicate that enzymatic activity is indispensable for the antimicrobial activity of lysozyme. However, partial heat denaturation extended the activity spectrum of lysozyme under pressure to serovar Typhimurium, suggesting enhanced uptake of partially denatured lysozyme through the serovar Typhimurium outer membrane. All test bacteria were sensitized by high pressure to a peptide corresponding to amino acid residues 96 to 116 of hen egg white, and all except
E. coli
and
P. fluorescens
were sensitized by high pressure to a peptide corresponding to amino acid residues 143 to 155 of T4 lysozyme. Since they are not enzymatically active, these peptides probably have a different mechanism of action than all lysozyme polypeptides.
Peptide Synthetase Gene in
Trichoderma virens
Authors: Wilhite S. E. , Lumsden R. D. , Straney D. C. 
Published: July 2002

ABSTRACT

Trichoderma virens
(synonym,
Gliocladium virens
), a deuteromycete fungus, suppresses soilborne plant diseases caused by a number of fungi and is used as a biocontrol agent. Several traits that may contribute to the antagonistic interactions of
T. virens
with disease-causing fungi involve the production of peptide metabolites (e.g., the antibiotic gliotoxin and siderophores used for iron acquisition). We cloned a 5,056-bp partial cDNA encoding a putative peptide synthetase (
Psy
1) from
T. virens
using conserved motifs found within the adenylate domain of peptide synthetases. Sequence similarities with conserved motifs of the adenylation domain, acyl transfer, and two condensation domains support identification of the
Psy
1 gene as a gene that encodes a peptide synthetase. Disruption of the native
Psy
1 gene through gene replacement was used to identify the function of this gene.
Psy
1 disruptants produced normal amounts of gliotoxin but grew poorly under low-iron conditions, suggesting that
Psy
1 plays a role in siderophore production.
Psy
1 disruptants cannot produce the major
T. virens
siderophore dimerum acid, a dipetide of acylated
N
δ
-hydroxyornithine. Biocontrol activity against damping-off diseases caused by
Pythium ultimum
and
Rhizoctonia solani
was not reduced by the
Psy
1 disruption, suggesting that iron competition through dimerum acid production does not contribute significantly to disease suppression activity under the conditions used.
Isolation, Characterization, and Polyaromatic Hydrocarbon Degradation Potential of Aerobic Bacteria from Marine Macrofaunal Burrow Sediments and Description ofLutibacterium anuloederansgen. nov., sp. nov., andCycloclasticus spirillensussp. nov
Authors: Chung W. K. , King G. M. 
Published: July 2002

ABSTRACTTwo new polyaromatic hydrocarbon-degrading marine bacteria have been isolated from burrow wall sediments of benthic macrofauna by using enrichments on phenanthrene. Strain LC8 (from a polychaete) and strain M4-6 (from a mollusc) are aerobic and gram negative and require sodium chloride (>1%) for growth. Both strains can use 2- and 3-ring polycyclic aromatic hydrocarbons as their sole carbon and energy sources, but they are nutritionally versatile. Physiological and phylogenetic analyses based on 16S ribosomal DNA sequences suggest that strain M4-6 belongs to the genusCycloclasticusand represents a new species,Cycloclasticus spirillensussp. nov. Strain LC8 appears to represent a new genus and species,Lutibacterium anuloederansgen. nov., sp. nov., within theSphingomonadaceae. However, when inoculated into sediment slurries with or without exogenous phenanthrene, onlyL. anuloederansappeared to sustain a significant phenanthrene uptake potential throughout a 35-day incubation. In addition, onlyL. anuloederansappeared to enhance phenanthrene degradation in heavily contaminated sediment from Little Mystic Cove, Boston Harbor, Boston, Mass.
Viability of
Giardia intestinalis
Cysts and Viability and Sporulation State of
Cyclospora cayetanensis
Oocysts Determined by Electrorotation
Authors: Dalton C. , Goater A. D. , Pethig R. , Smith H. V. 
Published: July 2002

ABSTRACT

Electrorotation is a noninvasive technique that is capable of detecting changes in the morphology and physicochemical properties of microorganisms. Electrorotation studies are reported for two intestinal parasites,
Giardia intestinalis
and
Cyclospora cayetanensis
. It is concluded that viable and nonviable
G. intestinalis
cysts can be differentiated by this technique, and support for this conclusion was obtained using a fluorogenic vital dye assay and morphological indicators. The viability of
C. cayetanensis
oocysts (for which no vital dye assay is currently available) can also be determined by electrorotation, as can their sporulation state. Modeling of the electrorotational response of these organisms was used to determine their dielectric properties and to gain an insight into the changes occurring within them. Electrorotation offers a new, simple, and rapid method for determining the viability of parasites in potable water and food products and as such has important healthcare implications.