bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro
Activity and
In Vivo
Efficacy of Posaconazole in Treatment of Murine Infections by Different Isolates of the
Aspergillus terreus
Complex
Authors: Salas Valentina , Pastor F. Javier , Rodríguez M. M. , Calvo Enrique , Mayayo Emilio , Guarro Josep 
Published: November 2010

ABSTRACT

Posaconazole (PSC) is an antifungal drug recommended as an alternative for the treatment of invasive aspergillosis in patients who are refractory or intolerant to primary antifungal therapy. We have evaluated the
in vitro
activity of PSC against 21 strains of the
Aspergillus terreus
complex using both broth microdilution and disk diffusion (Neo Sensitabs) methods. PSC showed the same high level of activity against all the strains with the two
in vitro
methods used. We developed a murine model of disseminated infection to evaluate the efficacy of PSC at 5, 10, or 20 mg/kg of body weight twice a day by using 6 different strains chosen randomly. PSC showed good efficacy, especially at 20 mg/kg, as measured by prolonged survival, tissue burden reduction, histopathology, and lowered galactomannan levels. The PSC levels in serum on the fourth day of treatment were higher than the MICs for the strains tested.
In Vitro
Antimicrobial Susceptibility of Bacterial Enteropathogens Isolated from International Travelers to Mexico, Guatemala, and India from 2006 to 2008
Authors: Ouyang-Latimer Jeannette , Jafri Syed , VanTassel Audrey , Jiang Zhi-Dong , Gurleen Kaur , Rodriguez Savio , Nandy Ranjan K. , Ramamurthy Thandavaryan , Chatterjee Santanu , McKenzie Robin , Steffen Robert , DuPont Herbert L. 
Published: November 2010

ABSTRACT

The incidence rates of travelers' diarrhea (TD) have remained high for the last 50 years. More recently, there have been increasing recommendations for self-initiated therapy and use of prophylactic drugs for TD. We last examined the
in vitro
susceptibilities of commonly used antibiotics against TD pathogens in 1997. We now examine 456 enteropathogens isolated from adult travelers to Mexico, India, and Guatemala with diarrhea acquired between 2006 and 2008 to determine changes in susceptibility against 10 different antimicrobials by the agar dilution method. Traditional antibiotics, such as ampicillin, trimethoprim-sulfamethoxazole, and doxycycline, continue to show high levels of resistance. Current first-line antibiotic agents, including fluoroquinolones and azithromycin, showed significantly higher MICs than in our earlier study, and MIC
90
levels were above the Clinical and Laboratory Standards Institute cutoffs for resistance. There were significant geographical differences in resistance patterns when Central America was compared with India. Entertoxigenic
Escherichia coli
(ETEC) isolates showed increased resistance to ciprofloxacin (
P
= 0.023) and levofloxacin (
P
= 0.0078) in India compared with Central America. Enteroaggregative
E. coli
(EAEC) isolates from Central America showed increased resistance to nearly all of the antibiotics tested. Compared to MICs of isolates 10 years prior, there were 4- to 10-fold increases in MIC
90
values for ceftriaxone, ciprofloxacin, levofloxacin, and azithromycin for both ETEC and EAEC. There were no significant changes in rifaximin MICs. Rising MICs over time imply the need for continuous surveillance of susceptibility patterns worldwide and geographically specific recommendations in TD therapy.
T-705 (Favipiravir) Inhibition of Arenavirus Replication in Cell Culture
Authors: Mendenhall Michelle , Russell Andrew , Juelich Terry , Messina Emily L. , Smee Donald F. , Freiberg Alexander N. , Holbrook Michael R. , Furuta Yousuke , de la Torre Juan-Carlos , Nunberg Jack H. , Gowen Brian B. 
Published: November 2010

ABSTRACTA number of New World arenaviruses (Junín [JUNV], Machupo [MACV], and Guanarito [GTOV] viruses) can cause human disease ranging from mild febrile illness to a severe and often fatal hemorrhagic fever syndrome. These highly pathogenic viruses and the Old World Lassa fever virus pose a significant threat to public health and national security. The only licensed antiviral agent with activity against these viruses, ribavirin, has had mixed success in treating severe arenaviral disease and is associated with significant toxicities. A novel pyrazine derivative currently in clinical trials for the treatment of influenza virus infections, T-705 (favipiravir), has demonstrated broad-spectrum activity against a number of RNA viruses, including arenaviruses. T-705 has also been shown to be effective against Pichinde arenavirus infection in a hamster model. Here, we demonstrate the robust antiviral activity of T-705 against authentic highly pathogenic arenaviruses in cell culture. We show that T-705 disrupts an early or intermediate stage in viral replication, distinct from absorption or release, and that its antiviral activity in cell culture is reversed by the addition of purine bases and nucleosides, but not with pyrimidines. Specific inhibition of viral replication/transcription by T-705 was demonstrated using a lymphocytic choriomeningitis arenavirus replicon system. Our findings indicate that T-705 acts to inhibit arenavirus replication/transcription and may directly target the viral RNA-dependent RNA polymerase.
Impact of Outpatient Antibiotic Use on Carriage of Ampicillin-Resistant
Escherichia coli
Authors: Samore Matthew H. , Tonnerre Claude , Hannah Elizabeth Lyon , Stoddard Gregory J. , Borotkanics Robert J. , Haddadin Bassam , Harbarth Stephan 
Published: November 2010

ABSTRACT

Studies about the relationship between antibiotic consumption and carriage of antibiotic-resistant
Escherichia coli
in individual patients have yielded conflicting results. The goal of this study was to identify individual- and household-level factors associated with carriage of ampicillin (AMP)-resistant
E. coli
during consumption of a course of oral antibiotics. We enrolled outpatients and their families in a prospective household study of AMP-resistant or AMP-susceptible
E. coli
carriage. Two kinds of index patients were identified. Group 1 consisted of outpatients who were being initiated on a new antibiotic course at the time of a clinic visit, and group 2 consisted of outpatients not starting antibiotics. Each participant was asked to submit three stool swab samples (at baseline, week 1, and week 4) and to complete a questionnaire. Antimicrobial susceptibility testing was performed on each phenotypically distinct
E. coli
colony. The study included 149 group 1 households (total, 570 participants) and 38 group 2 households (total, 131 participants). AMP-resistant
E. coli
was recovered from 29% of stool samples. Observed associations with antibiotic exposure varied by drug class. Penicillins, which were the most frequently prescribed drug class, were associated with a modest increase in AMP-resistant
E. coli
carriage and a modest decrease in AMP-susceptible
E. coli
carriage. Neither change by itself was statistically significant. Macrolides were associated with reduced carriage of both AMP-resistant
E. coli
and AMP-susceptible
E. coli
(
P
< 0.05). Both AMP-resistant and AMP-susceptible
E. coli
demonstrated household clustering (
P
< 0.001). In summary, the overall effect of antibiotics on individual risk of carriage of AMP-resistant
E. coli
was small. However, even a modest alteration of the competitive balance between AMP-resistant and AMP-susceptible
E. coli
may promote population spread of resistant
E. coli
. Examining changes in both resistant and susceptible organisms in antibiotic-treated individuals and their close contacts improves understanding of antibiotic selection pressure.
Quantification of the Relationship between Bacterial Kinetics and Host Response for Monkeys Exposed to Aerosolized
Francisella tularensis
Authors: Huang Yin , Haas Charles N. 
Published: November 2010

ABSTRACT

Francisella tularensis
can be disseminated via aerosols, and once inhaled, only a few microorganisms may result in tularemia pneumonia. Effective responses to this threat depend on a thorough understanding of the disease development and pathogenesis. In this study, a class of time-dose-response models was expanded to describe quantitatively the relationship between the temporal probability distribution of the host response and the
in vivo
bacterial kinetics. An extensive literature search was conducted to locate both the dose-dependent survival data and the
in vivo
bacterial count data of monkeys exposed to aerosolized
F. tularensis
. One study reporting responses of monkeys to four different sizes of aerosol particles (2.1, 7.5, 12.5, and 24.0 μm) of the SCHU S4 strain and three studies involving five
in vivo
growth curves of various strains (SCHU S4, 425, and live vaccine strains) initially delivered to hosts in aerosol form (1 to 5 μm) were found. The candidate models exhibited statistically acceptable fits to the time- and dose-dependent host response and provided estimates for the bacterial growth distribution. The variation pattern of such estimates with aerosol size was found to be consistent with the reported pathophysiological and clinical observations. The predicted growth curve for 2.1-μm aerosolized bacteria was highly consistent with the available bacterial count data. This is the first instance in which the relationship between the
in vivo
growth of
F
.
tularensis
and the host response can be quantified by mechanistic mathematical models.
Ecological Basis of the Interaction between
Pseudozyma flocculosa
and Powdery Mildew Fungi
Authors: Hammami Walid , Castro Candy Quiroga , Rémus-Borel Wilfried , Labbé Caroline , Bélanger Richard R. 
Published: November 2010

ABSTRACT

In this work, we sought to understand how glycolipid production and the availability of nutrients could explain the ecology of
Pseudozyma flocculosa
and its biocontrol activity. For this purpose, we compared the development of
P. flocculosa
to that of a close relative, the plant pathogen
Ustilago maydis
, under different environmental conditions. This approach was further supported by measuring the expression of
cyp1
, a pivotal gene in the synthesis of unique antifungal cellobiose lipids of both fungi. On healthy cucumber and tomato plants, the expression of
cyp1
remained unchanged over time in
P. flocculosa
and was undetected in
U. maydis
. At the same time, green fluorescent protein (GFP) strains of both fungi showed only limited green fluorescence on control leaves. On powdery mildew-infected cucumber leaves,
P. flocculosa
induced a complete collapse of the pathogen colonies, but glycolipid production, as studied by
cyp1
expression, was still comparable to that of controls. In complete contrast,
cyp1
was upregulated nine times when
P. flocculosa
was applied to
Botrytis cinerea
-infected leaves, but the biocontrol fungus did not develop very well on the pathogen. Analysis of the possible nutrients that could stimulate the growth of
P. flocculosa
on powdery mildew structures revealed that the complex Zn/Mn played a key role in the interaction. Other related fungi such as
U. maydis
do not appear to have the same nutritional requirements and hence lack the ability to colonize powdery mildews. Whether production of antifungal glycolipids contributes to the release of nutrients from powdery mildew colonies is unclear, but the specificity of the biocontrol activity of
P. flocculosa
toward Erysiphales does appear to be more complex than simple antibiosis.
Peptide Biomarkers as Evidence of Perchlorate Biodegradation
Authors: Bansal Reema , Crawford Ronald L. , Paszczynski Andrzej J. 
Published: November 2010

ABSTRACTPerchlorate is a known health hazard for humans, fish, and other species. Therefore, it is important to assess the response of an ecosystem exposed to perchlorate contamination. The data reported here show that a liquid chromatography-mass spectrometry-based proteomics approach for the detection of perchlorate-reducing enzymes can be used to measure the ability of microorganisms to degrade perchlorate, including determining the current perchlorate degradation status. Signature peptides derived from chlorite dismutase (CD) and perchlorate reductase can be used as biomarkers of perchlorate presence and biodegradation. Four peptides each derived from CD and perchlorate reductase subunit A (PcrA) and seven peptides derived from perchlorate reductase subunit B (PcrB) were identified as signature biomarkers for perchlorate degradation, as these sequences are conserved in the majority of the pure and mixed perchlorate-degrading microbial cultures examined. However, chlorite dismutase signature biomarker peptides fromDechloromonas agitataCKB were found to be different from those in other cultures used and should also be included with selected CD biomarkers. The combination of these peptides derived from the two enzymes represents a promising perchlorate presence/biodegradation biomarker system. The biomarker peptides were detected at perchlorate concentrations as low as 0.1 mM and at different time points both in pure cultures and within perchlorate-reducing environmental enrichment consortia. The peptide biomarkers were also detected in the simultaneous presence of perchlorate and an alternate electron acceptor, nitrate. We believe that this technique can be useful for monitoring bioremediation processes for other anthropogenic environmental contaminants with known metabolic pathways.
Determination of Serotypes of Shiga Toxin-ProducingEscherichia coliIsolates by Intact Cell Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry
Authors: Karger Axel , Ziller Mario , Bettin Barbara , Mintel Birgit , Schares Susann , Geue Lutz 
Published: November 2010

ABSTRACTShiga toxin-producingEscherichia coli(STEC) isolates representing the serotypes O165:H25, O26:H11/H32, and O156:H25 were analyzed by matrix-assisted laser desorption/ionization (MALDI) mass spectra of whole cells, a procedure also known as intact cell mass spectrometry (ICMS or IC-MALDI MS) or MALDI-typing. We demonstrate that within the given species the three serotypes can be well discriminated by ICMS. Conditions for the construction of serotype-specific prototypic mass spectra were systematically optimized by filtering out masses that do not contribute to the discrimination of the serotypes. Binary distances between prototypic spectra and sample spectra were used to determine serotypes of unknown samples. With parameters optimized, only 0.7% of the assignments were incorrect compared to 31% when distances were calculated from alignments of unfiltered mass spectra. Within the different serotypes, clusters of genetically relatedE. colimost probably originating from single clones could be distinguished by restriction fragment length polymorphism analysis. Since ICMS did not reproduce these clusters, we conclude that the power of ICMS is just sufficient to discriminateE. coliserotypes under certain conditions but fails for the differentiation ofE. colibelow this level.
Characterization of a Mannose-6-Phosphate Isomerase from
Thermus thermophilus
and Increased
l
-Ribose Production by Its R142N Mutant
Authors: Yeom Soo-Jin , Seo Eun-Sun , Kim Bi-Na , Kim Yeong-Su , Oh Deok-Kun 
Published: November 2010

ABSTRACT

An uncharacterized gene from
Thermus thermophilus
, thought to encode a mannose-6-phosphate isomerase, was cloned and expressed in
Escherichia coli
. The maximal activity of the recombinant enzyme for
l
-ribulose isomerization was observed at pH 7.0 and 75°C in the presence of 0.5 mM Cu
2+
. Among all of the pentoses and hexoses evaluated, the enzyme exhibited the highest activity for the conversion of
l
-ribulose to
l
-ribose, a potential starting material for many
l
-nucleoside-based pharmaceutical compounds. The active-site residues, predicted according to a homology-based model, were separately replaced with Ala. The residue at position 142 was correlated with an increase in
l
-ribulose isomerization activity. The R142N mutant showed the highest activity among mutants modified with Ala, Glu, Tyr, Lys, Asn, or Gln. The specific activity and catalytic efficiency (
k
cat
/

K
m

) for
l
-ribulose using the R142N mutant were 1.4- and 1.6-fold higher than those of the wild-type enzyme, respectively. The
k
cat
/

K
m

of the R142N mutant was 3.8-fold higher than that of
Geobacillus thermodenitrificans
mannose-6-phosphate isomerase, which exhibited the highest activity to date for the previously reported
k
cat
/

K
m

. The R142N mutant enzyme produced 213 g/liter
l
-ribose from 300 g/liter
l
-ribulose for 2 h, with a volumetric productivity of 107 g liter
−1
h
−1
, which was 1.5-fold higher than that of the wild-type enzyme.
Volatile-Mediated Killing of
Arabidopsis thaliana
by Bacteria Is Mainly Due to Hydrogen Cyanide
Authors: Blom Dirk , Fabbri Carlotta , Eberl Leo , Weisskopf Laure 
Published: November 2010

ABSTRACT

The volatile-mediated impact of bacteria on plant growth is well documented, and contrasting effects have been reported ranging from 6-fold plant promotion to plant killing. However, very little is known about the identity of the compounds responsible for these effects or the mechanisms involved in plant growth alteration. We hypothesized that hydrogen cyanide (HCN) is a major factor accounting for the observed volatile-mediated toxicity of some strains. Using a collection of environmental and clinical strains differing in cyanogenesis, as well as a defined HCN-negative mutant, we demonstrate that bacterial HCN accounts to a significant extent for the deleterious effects observed when growing
Arabidopsis thaliana
in the presence of certain bacterial volatiles. The environmental strain
Pseudomonas aeruginosa
PUPa3 was less cyanogenic and less plant growth inhibiting than the clinical strain
P. aeruginosa
PAO1. Quorum-sensing deficient mutants of
C. violaceum
CV0,
P. aeruginosa
PAO1, and
P. aeruginosa
PUPa3 showed not only diminished HCN production but also strongly reduced volatile-mediated phytotoxicity. The double treatment of providing plants with reactive oxygen species scavenging compounds and overexpressing the alternative oxidase AOX1a led to a significant reduction of volatile-mediated toxicity. This indicates that oxidative stress is a key process in the physiological changes leading to plant death upon exposure to toxic bacterial volatiles.
Modeling the Effects of Sodium Chloride, Acetic Acid, and Intracellular pH on Survival of
Escherichia coli
O157:H7
Authors: Hosein Althea M. , Breidt Frederick , Smith Charles E. 
Published: November 2010

ABSTRACT

Microbiological safety has been a critical issue for acid and acidified foods since it became clear that acid-tolerant pathogens such as
Escherichia coli
O157:H7 can survive (even though they are unable to grow) in a pH range of 3 to 4, which is typical for these classes of food products. The primary antimicrobial compounds in these products are acetic acid and NaCl, which can alter the intracellular physiology of
E. coli
O157:H7, leading to cell death. For combinations of acetic acid and NaCl at pH 3.2 (a pH value typical for non-heat-processed acidified vegetables), survival curves were described by using a Weibull model. The data revealed a protective effect of NaCl concentration on cell survival for selected acetic acid concentrations. The intracellular pH of an
E. coli
O157:H7 strain exposed to acetic acid concentrations of up to 40 mM and NaCl concentrations between 2 and 4% was determined. A reduction in the intracellular pH was observed for increasing acetic acid concentrations with an external pH of 3.2. Comparing intracellular pH with Weibull model predictions showed that decreases in intracellular pH were significantly correlated with the corresponding times required to achieve a 5-log reduction in the number of bacteria.
The Dependence of the
Yersinia
pestis
Capsule on Pathogenesis Is Influenced by the Mouse Background
Authors: Weening Eric H. , Cathelyn Jason S. , Kaufman Greer , Lawrenz Matthew B. , Price Paul , Goldman William E. , Miller Virginia L. 
Published: November 2010

ABSTRACT

Yersinia
pestis
is a highly pathogenic Gram-negative organism and the causative agent of bubonic and pneumonic plague.
Y
.
pestis
is capable of causing major epidemics; thus, there is a need for vaccine targets and a greater understanding of the role of these targets in pathogenesis. Two prime
Y
.
pestis
vaccine candidates are the usher-chaperone fimbriae Psa and Caf. Herein we report that
Y
.
pestis
requires, in a nonredundant manner, both PsaA and Caf1 to achieve its full pathogenic ability in both pneumonic and bubonic plague in C57BL/6J mice. Deletion of
psaA
leads to a decrease in the organ bacterial burden and to a significant increase in the 50% lethal dose (LD
50
) after subcutaneous infection. Deletion of
caf1
also leads to a significant decrease in the organ bacterial burden but more importantly leads to a significantly greater increase in the LD
50
than was observed for the Δ
psaA
mutant strain after subcutaneous infection of C57BL/6J mice. Furthermore, the degree of attenuation of the Δ
caf1
mutant strain is mouse background dependent, as the Δ
caf1
mutant strain was attenuated to a lesser degree in BALB/cJ mice by the subcutaneous route than in C57BL/6J mice. This observation that the degree of requirement for Caf1 is dependent on the mouse background indicates that the virulence of
Y
.
pestis
is dependent on the genetic makeup of its host and provides further support for the hypothesis that PsaA and Caf1 have different targets.
Comparative Kinetics ofEscherichia coli- andStaphylococcus aureus-Specific Activation of Key Immune Pathways in Mammary Epithelial Cells Demonstrates ThatS. aureusElicits a Delayed Response Dominated by Interleukin-6 (IL-6) but Not by IL-1A or Tumor Necrosis Factor Alpha
Authors: Günther Juliane , Esch Kathrin , Poschadel Norbert , Petzl Wolfram , Zerbe Holm , Mitterhuemer Simone , Blum Helmut , Seyfert Hans-Martin 
Published: November 2010

ABSTRACTInfections of the udder byEscherichia colivery often elicit acute inflammation, whileStaphylococcus aureusinfections tend to cause mild, subclinical inflammation and persistent infections. The molecular causes underlying the different disease patterns are poorly understood. We therefore profiled the kinetics and extents of global changes in the transcriptome of primary bovine mammary epithelial cells (MEC) after challenging them with heat-inactivated preparations ofE. coliorS. aureuspathogens.E. coliswiftly and strongly induced an expression of cytokines and bactericidal factors.S. aureuselicited a retarded response and failed to quickly induce an expression of bactericidal factors. Both pathogens induced similar patterns of chemokines for cell recruitment into the udder, butE. colistimulated their synthesis much faster and stronger. The genes that are exclusively and most strongly upregulated byE. colimay be clustered into a regulatory network with tumor necrosis factor alpha (TNF-α) and interleukin-1 (IL-1) in a central position. In contrast, the expression of these master cytokines is barely regulated byS. aureus. Both pathogens quickly trigger an enhanced expression of IL-6. This is still possible after completely abrogating MyD88-dependent Toll-like receptor (TLR) signaling in MEC. TheE. coli-specific strong induction of TNF-α and IL-1 expression may be causative for the severe inflammatory symptoms of animals suffering fromE. colimastitis, while the avoidance to quickly induce the synthesis of bactericidal factors may support the persistent survival ofS. aureuswithin the udder. We suggest thatS. aureussubverts the MyD88-dependent activation of immune gene expression in MEC.