bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transferable Quinolone Resistance in
Vibrio cholerae
Authors: Kim Hong Bin , Wang Minghua , Ahmed Sabeena , Park Chi Hye , LaRocque Regina C. , Faruque Abu S. G. , Salam Mohammed A. , Khan Wasif A. , Qadri Firdausi , Calderwood Stephen B. , Jacoby George A. , Hooper David C. 
Published: December 2009

ABSTRACT

Ciprofloxacin was introduced for treatment of patients with cholera in Bangladesh because of resistance to other agents, but its utility has been compromised by the decreasing ciprofloxacin susceptibility of
Vibrio cholerae
over time. We correlated levels of susceptibility and temporal patterns with the occurrence of mutation in
gyrA
, which encodes a subunit of DNA gyrase, followed by mutation in
parC
, which encodes a subunit of DNA topoisomerase IV. We found that ciprofloxacin activity was more recently further compromised in strains containing
qnrVC3
, which encodes a pentapeptide repeat protein of the Qnr subfamily, members of which protect topoisomerases from quinolone action. We show that
qnrVC3
confers transferable low-level quinolone resistance and is present within a member of the SXT integrating conjugative element family found commonly on the chromosomes of multidrug-resistant strains of
V. cholerae
and on the chromosomes of
Escherichia coli
transconjugants constructed in the laboratory. Thus, progressive increases in quinolone resistance in
V. cholerae
are linked to cumulative mutations in quinolone targets and most recently to a
qnr
gene on a mobile multidrug resistance element, resulting in further challenges for the antimicrobial therapy of cholera.
Chloroquine Modulates HIV-1-Induced Plasmacytoid Dendritic Cell Alpha Interferon: Implication for T-Cell Activation
Authors: Martinson Jeffrey A. , Montoya Carlos J. , Usuga Xiomara , Ronquillo Rollie , Landay Alan L. , Desai Seema N. 
Published: December 2009

ABSTRACT

Plasmacytoid dendritic cells (pDC) contribute to antiviral immunity mainly through recognition of microbial products and viruses via intracellular Toll-like receptor 7 (TLR7) or TLR9, resulting in the production of type I interferons (IFNs). Although interferons reduce the viral burden in the acute phase of infection, their role in the chronic phase is unclear. The presence of elevated plasma IFN-α levels in advanced HIV disease and its association with microbial translocation in chronic HIV infection lead us to hypothesize that IFN-α could contribute to immune activation. Blocking of IFN-α production using chloroquine, an endosomal inhibitor, was tested in a novel
in vitro
model system with the aim of characterizing the effects of chloroquine on HIV-1-mediated TLR signaling, IFN-α production, and T-cell activation. Our results indicate that chloroquine blocks TLR-mediated activation of pDC and MyD88 signaling, as shown by decreases in the levels of the downstream signaling molecules IRAK-4 and IRF-7 and by inhibition of IFN-α synthesis. Chloroquine decreased CD8 T-cell activation induced by aldrithiol-2-treated HIV-1 in peripheral blood mononuclear cell cultures. In addition to blocking pDC activation, chloroquine also blocked negative modulators of the T-cell response, such as indoleamine 2,3-dioxygenase (IDO) and programmed death ligand 1 (PDL-1). Our results indicate that TLR stimulation and production of IFN-α by pDC contribute to immune activation and that blocking of these pathways using chloroquine may interfere with events contributing to HIV pathogenesis. Our results suggests that a safe, well-tolerated drug such as chloroquine can be proposed as an adjuvant therapeutic candidate along with highly active antiretroviral therapy to control immune activation in HIV-1 infection.
Blockade of X4-Tropic HIV-1 Cellular Entry by GSK812397, a Potent Noncompetitive CXCR4 Receptor Antagonist
Authors: Jenkinson Stephen , Thomson Michael , McCoy David , Edelstein Mark , Danehower Susan , Lawrence Wendell , Wheelan Pat , Spaltenstein Andrew , Gudmundsson Kristjan 
Published: December 2009

ABSTRACT

GSK812397 is a potent entry inhibitor of X4-tropic strains of HIV-1, as demonstrated in multiple
in vitro
cellular assays (e.g., in peripheral blood mononuclear cells [PBMCs] and a viral human osteosarcoma [HOS] assay, mean 50% inhibitory concentrations [IC
50
s] ± standard errors of the means were 4.60 ± 1.23 nM and 1.50 ± 0.21 nM, respectively). The primary
in vitro
potency of GSK812397 was not significantly altered by the addition of serum proteins (2.55 [±0.12]-fold shift in the presence of human serum albumin and α-acid glycoprotein in the PBMC assay). Pharmacological characterization of GSK812397 in cell-based functional assays revealed it to be a noncompetitive antagonist of the CXCR4 receptor, with GSK812397 producing a concentration-dependent decrease in both an SDF-1-mediated chemotaxis and intracellular calcium release (IC
50
s were 0.34 ± 0.01 nM and 2.41 ± 0.50 nM, respectively). With respect to the antiviral activity of GSK812397, it was effective against a broad range of X4- and X4R5-utilizing clinical isolates. The potency and efficacy of GSK812397 were dependent on the individual isolate, with complete inhibition of infection observed with 24 of 30 isolates. GSK812397 did not show any detectable
in vitro
cytotoxicity and was highly selective for CXCR4, as determined using a wide range of receptors, enzymes, and transporters. Moreover, GSK812397 demonstrated acceptable pharmacokinetic properties and bioavailability across species. The data demonstrate that GSK812397 has antiviral activity against a broad range of X4-utilizing strains of HIV-1 via a noncompetitive antagonism of the CXCR4 receptor.
Effect of Biostimulation and Bioaugmentation on Degradation of Polyurethane Buried in Soil
Authors: Cosgrove L. , McGeechan P. L. , Handley P. S. , Robson G. D. 
Published: December 2009

ABSTRACT

This work investigated biostimulation and bioaugmentation as strategies for removing polyurethane (PU) waste in soil. Soil microcosms were biostimulated with the PU dispersion agent “Impranil” and/or yeast extract or were bioaugmented with PU-degrading fungi, and the degradation of subsequently buried PU was determined. Fungal communities in the soil and colonizing buried PU were enumerated on solid media and were analyzed using denaturing gradient gel electrophoresis (DGGE). Biostimulation with yeast extract alone or in conjunction with Impranil increased PU degradation 62% compared to the degradation in untreated control soil and was associated with a 45% increase in putative PU degraders colonizing PU. Specific fungi were enriched in soil following biostimulation; however, few of these fungi colonized the surface of buried PU. Fungi used for soil bioaugmentation were cultivated on the surface of sterile wheat to form a mycelium-rich inoculum. Wheat, when added alone to soil, increased PU degradation by 28%, suggesting that wheat biomass had a biostimulating effect. Addition of wheat colonized with
Nectria haematococca
,
Penicillium viridicatum
,
Penicillium ochrochloron
, or an unidentified
Mucormycotina
sp. increased PU degradation a further 30 to 70%, suggesting that biostimulation and bioaugmentation were operating in concert to enhance PU degradation. Interestingly, few of the inoculated fungi could be detected by DGGE in the soil or on the surface of the PU 4 weeks after inoculation. Bioaugmentation did, however, increase the numbers of indigenous PU-degrading fungi and caused an inoculum-dependent change in the composition of the native fungal populations, which may explain the increased degradation observed. These results demonstrate that both biostimulation and bioaugmentation may be viable tools for the remediation of environments contaminated with polyurethane waste.
Quantitative Detection of Human Adenoviruses in Wastewater and Combined Sewer Overflows Influencing a Michigan River
Authors: Fong Theng-Theng , Phanikumar Mantha S. , Xagoraraki Irene , Rose Joan B. 
Published: December 2009

ABSTRACT

Enteric viruses are important pathogens found in contaminated surface waters and have previously been detected in waters of the Great Lakes. Human adenoviruses were monitored because of their high prevalence and persistence in aquatic environments. In this study, we quantified adenoviruses in wastewater, surface water, and combined sewer overflows (CSOs) by real-time PCR. Between August 2005 and August 2006, adenovirus concentrations in raw sewage, primary-treated effluent, secondary-treated effluent, and chlorinated effluent from a wastewater treatment plant in Michigan were examined. CSO samples (
n
= 6) were collected from a CSO retention basin in Grand Rapids, MI. Adenoviruses were detected in 100% of wastewater and CSO discharge samples. Average adenovirus DNA concentrations in sewage and CSOs were 1.15 × 10
6
viruses/liter and 5.35 × 10
5
viruses/liter, respectively. Adenovirus removal was <2 log
10
(99%) at the wastewater treatment plant. Adenovirus type 41 (60% of clones), type 12 (29%), type 40 (3%), type 2 (3%), and type 3 (3%) were isolated from raw sewage and primary effluents (
n
= 28). Six of 20 surface water samples from recreational parks at the lower Grand River showed virus concentrations above the real-time PCR detection limit (average, 7.8 × 10
3
viruses/liter). This research demonstrates that wastewater effluents and wastewater-impacted surface waters in the lower Grand River in Michigan contain high levels of viruses and may not be suitable for full-body recreational activities. High concentrations of adenovirus in these waters may be due to inefficient removal during wastewater treatment and to the high persistence of these viruses in the environment.
Synergistic Effects of the
Lactobacillus acidophilus
Surface Layer and Nisin on Bacterial Growth
Authors: Prado-Acosta Mariano , Ruzal Sandra M. , Allievi Mariana C. , Palomino María Mercedes , Sanchez Rivas Carmen 
Published: December 2009

ABSTRACT

We have previously described a murein hydrolase activity for the surface layer (S-layer) of
Lactobacillus acidophilus
ATCC 4356. Here we show that, in combination with nisin, this S-layer acts synergistically to inhibit the growth of pathogenic Gram-negative
Salmonella enterica
and potential pathogenic Gram-positive bacteria,
Staphylococcus aureus
and
Bacillus cereus.
In addition, bacteriolytic effects were observed for the Gram-positive species tested. We postulate that the S-layer enhances the access of nisin into the cell membrane by enabling it to cross the cell wall, while nisin provides the sudden ion-nonspecific dissipation of the proton motive force required to enhance the S-layer murein hydrolase activity.
Determination of the Diversity of
Rhodopirellula
Isolates from European Seas by Multilocus Sequence Analysis
Authors: Winkelmann Nadine , Jaekel Ulrike , Meyer Carolin , Serrano Wilbert , Rachel Reinhard , Rosselló-Mora Ramon , Harder Jens 
Published: December 2009

ABSTRACT

In the biogeography of microorganisms, the habitat size of an attached-living bacterium has never been investigated. We approached this theme with a multilocus sequence analysis (MLSA) study of new strains of
Rhodopirellula
sp., an attached-living planctomycete. The development of an MLSA for
Rhodopirellula baltica
enabled the characterization of the genetic diversity at the species level, beyond the resolution of the 16S rRNA gene. The alleles of the nine housekeeping genes
acsA
,
guaA
,
trpE
,
purH
,
glpF
,
fumC
,
icd
,
glyA
, and
mdh
indicated the presence of 13 genetically defined operational taxonomic units (OTUs) in our culture collection. The MLSA-based OTUs coincided with the taxonomic units defined by DNA-DNA hybridization experiments. BOX-PCR supported the MLSA-based differentiation of two closely related OTUs. This study established a taxon-area relationship of cultivable
Rhodopirellula
species. In European seas, three closely related species covered the Baltic Sea and the eastern North Sea, the North Atlantic region, and the southern North Sea to the Mediterranean. The last had regional genotypes, as revealed by BOX-PCR. This suggests a limited habitat size of attached-living
Rhodopirellula
species.
Coupling of Denaturing High-Performance Liquid Chromatography and Terminal Restriction Fragment Length Polymorphism with Precise Fragment Sizing for Microbial Community Profiling and Characterization
Authors: Penny Christian , Nadalig Thierry , Alioua Malek , Gruffaz Christelle , Vuilleumier Stéphane , Bringel Françoise 
Published: December 2009

ABSTRACT
Terminal restriction fragment length polymorphism (T-RFLP) is used to monitor the structural diversity of complex microbial communities in terms of richness, relative abundance, and distribution of the major subpopulations and individual members. However, discrepancies of several nucleotides between expected and experimentally observed lengths of terminal restriction fragments (T-RFs), together with the difficulty of obtaining DNA sequence information from T-RFLP profiling, often prevent accurate phylogenetic characterization of the microbial community of interest. In this study, T-RFLP analysis of DNA from an artificial assembly of five bacterial strains was carried out with a combination of two size markers with different fluorescent tags. Precise sizing of T-RFs in the 50- to 500-nucleotide range was achieved by using the same dye for both samples and size markers. Phylogenetic assignment of the component microbial strains was facilitated by coupling T-RFLP to denaturing high-performance liquid chromatography (D-HPLC) of 16S RNA gene fragments followed by direct sequencing. The proposed coupling of D-HPLC and T-RFLP provides unambiguous characterization of microbial communities containing less than 15 microbial strains.
Rapid Evaluation of the Mycobactericidal Efficacy of Disinfectants in the Quantitative Carrier Test EN 14563 by Using Fluorescent
Mycobacterium terrae
Authors: Steinhauer Katrin , Eschenbacher Iris , Radischat Nadine , Detsch Christian , Niederweis Michael , Goroncy-Bermes Peter 
Published: December 2009

ABSTRACT

To prevent transmission of mycobacterial pathogens, medical devices must be disinfected by germicides with proven mycobactericidal activity. The quantitative carrier test EN 14563 provides an international standard for evaluation of the mycobactericidal activity of disinfectants under practical conditions. However, tests according to the EN 14563 standard are based on cultivation, and results are available only after 21 days. The aim of this study was to accelerate assessment of dosage and contact times of mycobactericidal preparations based on the EN 14563 standard. To this end, a
gfp
gene was constructed with a codon usage adapted for
Mycobacterium tuberculosis
. Expression of the
gfp
m
2+
gene in
Mycobacterium terrae
improved the detection sensitivity by 10-fold over that with a previously used reporter strain. Peracetic acid and a cation-active formulation were tested as commercially available disinfectants for medical devices.
M. terrae
expressing
gfp
m
2+
was used to determine dosage and contact times for the two test germicides. Fluorescence measurements correlated well with growth of the reporter strain, demonstrating that the fluorescence reliably indicated the number of viable cells. The fluorescence enabled us to determine the mycobactericidal efficacy of the test disinfectants according to the quantitative carrier test EN 14563 standard within at least 15 days. In conclusion, this study establishes
gfp
m
2+
-expressing
M. terrae
as a new reporter strain for reliable evaluation of mycobactericidal activities of disinfectants with a superior sensitivity and in a significantly shorter time than previously possible.
Molecular Detection of Viable Bacterial Pathogens in Water by Ratiometric Pre-rRNA Analysis
Authors: Cangelosi Gerard A. , Weigel Kris M. , Lefthand-Begay Clarita , Meschke John S. 
Published: December 2009

ABSTRACT
Ratiometric pre-rRNA analysis (RPA) detects the replenishment of rRNA precursors that occurs rapidly upon nutritional stimulation of bacterial cells. In contrast to DNA detection by PCR, RPA distinguishes viable from inactivated bacteria. It exhibits promise as a molecular viability test for pathogens in water and other environmental samples.
Distribution of Cepacian Biosynthesis Genes among Environmental and Clinical
Burkholderia
Strains and Role of Cepacian Exopolysaccharide in Resistance to Stress Conditions
Authors: Ferreira Ana S. , Leitão Jorge H. , Silva Inês N. , Pinheiro Pedro F. , Sousa Sílvia A. , Ramos Christian G. , Moreira Leonilde M. 
Published: December 2009

ABSTRACT

The genus
Burkholderia
includes strains pathogenic to animals and plants, bioremediators, or plant growth promoters. Genome sequence analyses of representative
Burkholderia cepacia
complex (
Bc
c) and non-
Bc
c strains for the presence of the
bce-I
gene cluster, directing the biosynthesis of the exopolysaccharide (EPS) cepacian, further extended this previously described cluster by another 9 genes. The genes in the
bce-II
cluster were named
bceM
to
bceU
and encode products putatively involved in nucleotide sugar precursor biosynthesis and repeat unit assembly, modification, and translocation across the cytoplasmic membrane. Disruption of the
B. cepacia
IST408
bceQ
and
bceR
genes, encoding a putative repeat unit flippase and a glycosyltransferase, respectively, resulted in the abolishment of cepacian biosynthesis. A mutation in the
bceS
gene, encoding a putative acyltransferase, did not affect EPS production yield significantly but decreased its acetylation content by approximately 20%. Quantitative real-time reverse transcription-PCR experiments confirmed the induction of genes in the
bce-I
and
bce-II
clusters in a
B
urkholderia multivorans
EPS producer clinical isolate in comparison to the level for its isogenic EPS-defective strain. Fourier Transform infrared spectroscopy analysis confirmed that the exopolysaccharide produced by 10
Burkholderia
isolates tested was cepacian. The ability of
Burkholderia
strains to withstand desiccation and metal ion stress was higher when bacteria were incubated in the presence of 2.5 g/liter of cepacian, suggesting that this EPS plays a role in the survival of these bacteria by contributing to their ability to thrive in different environments.
Conjugative Transfer of Insecticidal Plasmid pHT73 from
Bacillus thuringiensis
to
B. anthracis
and Compatibility of This Plasmid with pXO1 and pXO2
Authors: Yuan Yongming , Zheng Dasheng , Hu Xiaomin , Cai Quanxin , Yuan Zhiming 
Published: December 2009

ABSTRACT

Bacillus anthracis
, the etiologic agent of anthrax, is genetically close to and commonly shares a giant gene pool with
B. cereus
and
B. thuringiensis
. In view of the human pathogenicity and the long persistence in the environment of
B. anthracis
, there is growing concern about the effects of genetic exchange with
B. anthracis
on public health. In this work, we demonstrate that an insecticidal plasmid, pHT73, from
B. thuringiensis
strain KT0 could be efficiently transferred into two attenuated
B. anthracis
strains, Ba63002R (pXO1
+
pXO2
−
) and Ba63605R (pXO1
−
pXO2
+
), by conjugation in liquid medium in the laboratory, with transfer rates of 2.3 × 10
−4
and 1.6 × 10
−4
CFU/donor, respectively. The
B. anthracis
transconjugants containing both pHT73 and pXO1 or pXO2 could produce crystal protein Cry1Ac encoded by plasmid pHT73 and had high toxicity to
Helicoverpa armigera
larvae. Furthermore, the compatibility and stability of pHT73 with pXO1/pXO2 were demonstrated. The data are informative for further investigation of the safety of
B. thuringiensis
and closely related strains in food and in the environment.
Genetic Analysis for the Lack of Expression of the O157 Antigen in an O Rough:H7
Escherichia coli
Strain
Authors: Rump Lydia V. , Feng Peter C. H. , Fischer Markus , Monday Steven R. 
Published: December 2009

ABSTRACT

The O-antigen (
rfb
) operon and related genes of MA6, an O rough:H7 Shiga-toxigenic
Escherichia coli
strain, were examined to determine the cause of the lack of O157 expression. A 1,310-bp insertion, homologous to IS
629
, was observed within its
gne
gene.
trans
complementation with a functional
gne
gene from O157:H7 restored O157 antigen expression in MA6.
Broad Habitat Range of the Phylogenetically Narrow R-BT065 Cluster, Representing a Core Group of the Betaproteobacterial Genus
Limnohabitans
Authors: Šimek Karel , Kasalický Vojtěch , Jezbera Jan , Jezberová Jitka , Hejzlar Josef , Hahn Martin W. 
Published: December 2009

ABSTRACT

The distribution of the phylogenetically narrow R-BT065 cluster (
Betaproteobacteria
) in 102 freshwater lakes, reservoirs, and various ponds located in central Europe (a total of 122 samples) was examined by using a cluster-specific fluorescence in situ hybridization probe. These habitats differ markedly in pH, conductivity, trophic status, surface area, altitude, bedrock type, and other limnological characteristics. Despite the broad ecological diversity of the habitats investigated, the cluster was detected in 96.7% of the systems, and its occurrence was not restricted to a certain habitat type. However, the relative proportions of the cluster in the total bacterioplankton were significantly lower in humic and acidified lakes than in pH-neutral or alkaline habitats. On average, the cluster accounted for 9.4% of the total bacterioplankton (range, 0 to 29%). The relative abundance and absolute abundance of these bacteria were significantly and positively related to higher pH, conductivity, and the proportion of low-molecular-weight compounds in dissolved organic carbon (DOC) and negatively related to the total DOC and dissolved aromatic carbon contents. Together, these parameters explained 55.3% of the variability in the occurrence of the cluster. Surprisingly, no clear relationship of the R-BT065 bacteria to factors indicating the trophic status of habitats (i.e., different forms of phosphorus and chlorophyll a content) was found. Based on our results and previously published data, we concluded that the R-BT065 cluster represents a ubiquitous, highly active segment of bacterioplankton in nonacidic lakes and ponds and that alga-derived substrates likely form the main pool of substrates responsible for its high growth potential and broad distribution in freshwater habitats.