bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Virulence and Antimicrobial Resistance DNA Microarray Detects a High Frequency of Virulence Genes in
Escherichia coli
Isolates from Great Lakes Recreational Waters
Authors: Hamelin Katia , Bruant Guillaume , El-Shaarawi Abdel , Hill Stephen , Edge Thomas A. , Bekal Sadjia , Fairbrother John Morris , Harel Josée , Maynard Christine , Masson Luke , Brousseau Roland 
Published: June 2006

ABSTRACT

Escherichia coli
is generally described as a commensal species with occasional pathogenic strains. Due to technological limitations, there is currently little information concerning the prevalence of pathogenic
E. coli
strains in the environment. For the first time, using a DNA microarray capable of detecting all currently described virulence genes and commonly found antimicrobial resistance genes, a survey of environmental
E. coli
isolates from recreational waters was carried out. A high proportion (29%) of 308 isolates from a beach site in the Great Lakes carried a pathotype set of virulence-related genes, and 14% carried antimicrobial resistance genes, findings consistent with a potential risk for public health. The results also showed that another 8% of the isolates had unusual virulence gene combinations that would be missed by conventional screening. This new application of a DNA microarray to environmental waters will likely have an important impact on public health, epidemiology, and microbial ecology in the future.
Validation of AKACID Plus as a Room Disinfectant in the Hospital Setting
Authors: Kratzer Christina , Tobudic Selma , Assadian Ojan , Buxbaum Astrid , Graninger Wolfgang , Georgopoulos Apostolos 
Published: June 2006

ABSTRACT

AKACID Plus, a novel polymeric guanidine with broad antimicrobial activity against multiantibiotic-resistant bacterial strains, was used in the present study as a room disinfectant. Disinfection of closed rooms experimentally contaminated with antibiotic-susceptible and multiresistant
Staphylococcus aureus
(MRSA),
Pseudomonas aeruginosa
, and
Escherichia coli
was performed using AKACID Plus at concentrations of 0.1, 0.25, and 0.5% for 100 min. Bacterial suspensions were distributed on plastic and stainless steel plates and placed in a test room. Recovery of the test microorganisms was determined before nebulizing, 60 and 100 min after initiation, and 4 h after the end of room disinfection by a simple swab-rinse technique. The swab-rinse method demonstrated a dose- and time-dependent effectiveness of AKACID Plus in eradicating
S. aureus
,
E. coli
, and
P. aeruginosa
on plastic and stainless steel plates. Nebulized 0.5% AKACID Plus was successful in eliminating all hospital pathogens within 340 min. After the use of 0.25% AKACID Plus, MRSA was still detectable on microbial carrier plates. The test concentration of 0.1% AKACID Plus achieved a significant reduction of
S. aureus
and
P. aeruginosa
on plastic and stainless steel plates but was sufficient to eradicate only
E. coli
. These results suggest that nebulized AKACID Plus at a concentration of 0.5% is a potent substance for eradication of pathogenic organisms in the hospital setting.
Isolation, Characterization, and Heterologous Expression of the Biosynthesis Gene Cluster for the Antitumor Anthracycline Steffimycin
Authors: Gullón Sonia , Olano Carlos , Abdelfattah Mohamed S. , Braña Alfredo F. , Rohr Jürgen , Méndez Carmen , Salas José A. 
Published: June 2006

ABSTRACT

The biosynthetic gene cluster for the aromatic polyketide steffimycin of the anthracycline family has been cloned and characterized from “
Streptomyces steffisburgensis
” NRRL 3193. Sequence analysis of a 42.8-kbp DNA region revealed the presence of 36 open reading frames (ORFs) (one of them incomplete), 24 of which, spanning 26.5 kb, are probably involved in steffimycin biosynthesis. They code for all the activities required for polyketide biosynthesis, tailoring, regulation, and resistance but show no evidence of genes involved in
l
-rhamnose biosynthesis. The involvement of the cluster in steffimycin biosynthesis was confirmed by expression of a region of about 15 kb containing 15 ORFS, 11 of them forming part of the cluster, in the heterologous host
Streptomyces albus
, allowing the isolation of a biosynthetic intermediate. In addition, the expression in
S. albus
of the entire cluster, contained in a region of 34.8 kb, combined with the expression of plasmid pRHAM, directing the biosynthesis of
l
-rhamnose, led to the production of steffimycin. Inactivation of the
stfX
gene, coding for a putative cyclase, revealed that this enzymatic activity participates in the cyclization of the fourth ring, making the final steps in the biosynthesis of the steffimycin aglycon similar to those in the biosynthesis of jadomycin or rabelomycin. Inactivation of the
stfG
gene, coding for a putative glycosyltransferase involved in the attachment of
l
-rhamnose, allowed the production of a new compound corresponding to the steffimycin aglycon compound also observed in
S. albus
upon expression of the entire cluster.
Identification of a DNA Methyltransferase Gene Carried on a Pathogenicity Island-Like Element (VPAI) in
Vibrio parahaemolyticus
and Its Prevalence among Clinical and Environmental Isolates
Authors: Wang Hui-zhen , Wong Minnie M. L. , O'Toole Desmond , Mak Mandy M. H. , Wu Rudolf S. S. , Kong Richard Y. C. 
Published: June 2006

ABSTRACT

In this study we identified a putative virulence-associated DNA methyltransferase (MTase) gene carried on a novel 22.79-kb pathogenicity island-like element (VPAI) in
V. parahaemolyticus
. The
V. parahaemolyticus
MTase gene was shown by PCR to be prevalent (>98%) in pandemic thermostable direct hemolysin gene-positive isolates, which suggests that VPAI may confer unique virulence traits to pandemic strains of
V. parahaemolyticus
.
Effect of P Availability on Temporal Dynamics of Carbon Allocation and
Glomus intraradices
High-Affinity P Transporter Gene Induction in Arbuscular Mycorrhiza
Authors: Olsson Pål Axel , Hansson Maria C. , Burleigh Stephen H. 
Published: June 2006

ABSTRACT

Arbuscular mycorrhizal (AM) fungi depend on a C supply from the plant host and simultaneously provide phosphorus to the colonized plant. We therefore evaluated the influence of external P on C allocation in monoxenic
Daucus carota
-
Glomus intraradices
cultures in an AM symbiosis. Fungal hyphae proliferated from a solid minimal medium containing colonized roots into a C-free liquid minimal medium with high or low P availability. Roots and hyphae were harvested periodically, and the flow of C from roots to fungus was measured by isotope labeling. We also measured induction of a
G. intraradices
high-affinity P transporter to estimate fungal P demand. The prevailing hypothesis is that high P availability reduces mycorrhizal fungal growth, but we found that C flow to the fungus was initially highest at the high P level. Only at later harvests, after 100 days of in vitro culture, were C flow and fungal growth limited at high P availability. Thus, AM fungi can benefit initially from P-enriched environments in terms of plant C allocation. As expected, the P transporter induction was significantly greater at low P availability and greatest in very young mycelia. We found no direct link between C flow to the fungus and the P transporter transcription level, which indicates that a good C supply is not essential for induction of the high-affinity P transporter. We describe a mechanism by which P regulates symbiotic C allocation, and we discuss how this mechanism may have evolved in a competitive environment.
Microbial Diversity in Maras Salterns, a Hypersaline Environment in the Peruvian Andes
Authors: Maturrano Lenin , Santos Fernando , Rosselló-Mora Ramon , Antón Josefa 
Published: June 2006

ABSTRACTMaras salterns are located 3,380 m above sea level in the Peruvian Andes. These salterns consist of more than 3,000 little ponds which are not interconnected and act as crystallizers where salt precipitates. These ponds are fed by hypersaline spring water rich in sodium and chloride. The microbiota inhabiting these salterns was examined by fluorescence in situ hybridization (FISH), 16S rRNA gene clone library analysis, and cultivation techniques. The total counts per milliliter in the ponds were around 2 × 106to 3 × 106cells/ml, while the spring water contained less than 100 cells/ml and did not yield any detectable FISH signal. The microbiota inhabiting the ponds was dominated (80 to 86% of the total counts) byArchaea, whileBacteriaaccounted for 10 to 13% of the 4′,6′-diamidino-2-phenylindole (DAPI) counts. A total of 239 16S rRNA gene clones were analyzed (132Archaeaclones and 107Bacteriaclones). According to the clone libraries, the archaeal assemblage was dominated by microorganisms related to the cosmopolitan square archaeon “Haloquadra walsbyi,” although a substantial number of the sequences in the libraries (31% of the 16S rRNA gene archaeal clones) were related toHalobacteriumsp., which is not normally found in clone libraries from solar salterns. All the bacterial clones were closely related to each other and to the γ-proteobacterium “Pseudomonas halophila” DSM 3050. FISH analysis with a probe specific for this bacterial assemblage revealed that it accounted for 69 to 76% of the total bacterial counts detected with aBacteria-specific probe. When pond water was used to inoculate solid media containing 25% total salts, both extremely halophilicArchaeaandBacteriawere isolated. Archaeal isolates were not related to the isolates in clone libraries, although several bacterial isolates were very closely related to the “P. halophila” cluster found in the libraries. As observed for other hypersaline environments, extremely halophilic bacteria that had ecological relevance seemed to be easier to culture than their archaeal counterparts.
Field Trial Evaluating the Influence of Prophylactic and Therapeutic Antimicrobial Administration on Antimicrobial Resistance of Fecal
Escherichia coli
in Dairy Calves
Authors: Berge Anna Catharina B. , Moore Dale A. , Sischo William M. 
Published: June 2006

ABSTRACT

The objective of this study was to describe the influence of in-feed and therapeutic antimicrobials on resistance in commensal fecal
Escherichia coli
isolated from preweaned calves. Four groups of 30, day-old calf-ranch calves were enrolled and raised until 4 weeks of age. Groups 1 to 3 were raised without antimicrobials in the feed. Group 1 was isolated from the other groups and received no antimicrobial therapy. Group 2 was housed on the calf ranch and did not receive antimicrobial therapy, whereas groups 3 and 4 could be treated with antimicrobials. Group 4 was fed neomycin and tetracycline HCl in the milk replacer. Fecal samples were collected from calves on days 1, 14, and 28. Three
E. coli
isolates per sample were evaluated for susceptibility to 12 antimicrobials. Cluster analysis was used to group isolates having similar susceptibility patterns. Cumulative logistic regression was used to evaluate factors associated with increasing levels of multiple antimicrobial resistance. In-feed antimicrobials were associated with higher levels of multiple antimicrobial resistance in fecal
E. coli
.f In calves not receiving in-feed antimicrobials, older calves had higher levels of resistance compared to day-old calves. Individual antimicrobial therapy increased resistance in these calves but appeared to be transient. There was no environmental influence on resistance in
E. coli
populations among study groups.
Rapid One-Step Quantitative Reverse Transcriptase PCR Assay with Competitive Internal Positive Control for Detection of Enteroviruses in Environmental Samples
Authors: Gregory Jason B. , Litaker R. Wayne , Noble Rachel T. 
Published: June 2006

ABSTRACT
Human enteroviruses can serve as a more accurate indicator of human fecal contamination than conventional bacteriological fecal indicators. We describe here a quantitative reverse transcriptase PCR (qRT-PCR) assay specifically tailored to detect these viruses in environmental waters. The assay included a competitive internal positive control (CIPC) that allowed the inhibition of qRT-PCRs to be quantitatively assessed. Coamplification of the CIPC with enteroviral genetic material did not affect the sensitivity, specificity, or reproducibility of the enteroviral qRT-PCR assay. The assay is rapid (less than 5 h from sample to result), has a wide dynamic range (>3 logs), and is capable of detecting as few as 25 enteroviral genomes with an average amplification efficiency of 0.91. In samples with low or moderate inhibition, the delay in CIPC amplification was used to adjust enterovirus qRT-PCR concentrations to account for losses due to inhibition. Samples exhibiting significant inhibition were not corrected but instead diluted twofold and immediately assayed again. Using significantly inhibited samples, it was found that dilution relieved inhibition in 93% (25 of 27) of the samples. In addition, 15% (4 of 27) of these previously negative samples contained enteroviral genomes. The high-throughput format of the assay compared to conventional culture-based methods offers a fast, reliable, and specific method for detecting enteroviruses in environmental water samples. The ability of the assay to identify false negatives and provide improved quantitative assessments of enterovirus concentrations will facilitate the tracking of human fecal contamination and the assessment of potential public health risk due to enteroviruses in recreational and shellfish harvesting waters.
Biodiversity and Classification of Lactococcal Phages
Authors: Deveau Hélène , Labrie Simon J. , Chopin Marie-Christine , Moineau Sylvain 
Published: June 2006

ABSTRACTFor this study, an in-depth review of the classification ofLactococcus lactisphages was performed. Reference phages as well as unclassified phages from international collections were analyzed by stringent DNA-DNA hybridization studies, electron microscopy observations, and sequence analyses. A new classification scheme for lactococcal phages is proposed that reduces the current 12 groups to 8. However, two new phages (Q54 and 1706), which are unrelated to known lactococcal phages, may belong to new emerging groups. The multiplex PCR method currently used for the rapid identification of phages from the three main lactococcal groups (936, c2, and P335) was improved and tested against the other groups, none of which gave a PCR product, confirming the specificity of this detection tool. However, this method does not detect all members of the highly diverse P335 group. The lactococcal phages characterized here were deposited in the Félix d'Hérelle Reference Center for Bacterial Viruses and represent a highly diverse viral community from the dairy environment.
Heterologous Expression of
Arabidopsis
UDP-Glucosyltransferases in
Saccharomyces cerevisiae
for Production of Zearalenone-4-
O
-Glucoside
Authors: Poppenberger Brigitte , Berthiller Franz , Bachmann Herwig , Lucyshyn Doris , Peterbauer Clemens , Mitterbauer Rudolf , Schuhmacher Rainer , Krska Rudolf , Glössl Josef , Adam Gerhard 
Published: June 2006

ABSTRACT

Zearalenone, a secondary metabolite produced by several plant-pathogenic fungi of the genus
Fusarium
, has high estrogenic activity in vertebrates. We developed a
Saccharomyces cerevisiae
bioassay strain that we used to identify plant genes encoding UDP-glucosyltransferases that can convert zearalenone into zearalenone-4-
O
-glucoside (ZON-4-
O
-Glc). Attachment of the glucose moiety to zearalenone prevented the interaction of the mycotoxin with the human estrogen receptor. We found that two of six clustered, similar
UGT73C
genes of
Arabidopsis thaliana
encode glucosyltransferases that can inactivate zearalenone in the yeast bioassay. The formation of glucose conjugates seems to be an important plant mechanism for coping with zearalenone but may result in significant amounts of “masked” zearalenone in
Fusarium
-infected plant products. Due to the unavailability of an analytical standard, the ZON-4-
O
-Glc is not measured in routine analytical procedures, even though it can be converted back to active zearalenone in the digestive tracts of animals. Zearalenone added to yeast transformed with UGT73C6 was converted rapidly and efficiently to ZON-4-
O
-Glc, suggesting that the cloned UDP-glucosyltransferase could be used to produce reference glucosides of zearalenone and its derivatives.
Stability and Performance of
Xanthobacter autotrophicus
GJ10 during 1,2-Dichloroethane Biodegradation
Authors: Baptista Ines I. R. , Peeva Ludmila G. , Zhou Ning-Yi , Leak David J. , Mantalaris Athanasios , Livingston Andrew G. 
Published: June 2006

ABSTRACT

A nucleic acid-based approach was used to investigate the dynamics of a microbial community dominated by
Xanthobacter autotrophicus
GJ10 in the degradation of synthetic wastewater containing 1,2-dichloroethane (DCE). This study was performed over a 140-day period in a nonsterile continuous stirred-tank bioreactor (CSTB) subjected to different operational regimens: nutrient-limiting conditions, baseline operation, and the introduction of glucose as a cosubstrate. The microbial community was analyzed by a combination of fluorescence in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE). Under nutrient-limiting conditions, DCE degradation was restricted, but this did not affect the dominance of strain GJ10, determined by FISH to comprise 85% of the active population. During baseline operation, DCE degradation improved significantly to over 99.5% and then remained constant throughout the subsequent experimental period. DGGE profiles revealed a stable, complex community, while FISH indicated that strain GJ10 remained the dominant species. During the addition of glucose as a cosubstrate, DGGE profiles showed a proliferation of other species in the CSTB. The percentage of strain GJ10 dropped to 8% of the active population in just 5 days, although this did not affect the DCE biodegradation performance. The return to baseline conditions was accompanied by the reestablishment of strain GJ10 as the dominant species, suggesting that this system responds robustly to external perturbations, both at the functional biodegradation level and at the individual strain level.
A Cold-Sensitive
Listeria monocytogenes
Mutant Has a Transposon Insertion in a Gene Encoding a Putative Membrane Protein and Shows Altered (p)ppGpp Levels
Authors: Liu Siqing , Bayles Darrell O. , Mason Tricia M. , Wilkinson Brian J. 
Published: June 2006

ABSTRACT

A cold-sensitive
Listeria monocytogenes
mutant designated cld-14 was obtained by transposon Tn
917
mutagenesis. The gene interrupted by Tn
917
in cld-14 was the
L. monocytogenes
LMOf2365_
1485
homolog, which exhibits 45.7% homology to the
Bacillus subtilis yqfF
locus. LMOf2365_
1485
, here designated
pgpH
, encodes a putative integral membrane protein with a predicted molecular mass of 81 kDa. PgpH is predicted to contain a conserved N-terminal signal peptide sequence, seven transmembrane helices, and a hydrophilic C terminus, which likely extends into the cytosol. The Tn
917
insertion in
pgpH
is predicted to result in production of a premature polypeptide truncated at the fifth transmembrane domain. The C terminus of PgpH, which is probably absent in cld-14, contains a highly conserved HD domain that belongs to a metal-dependent phosphohydrolase family. Strain cld-14 accumulated higher levels of (p)ppGpp than the wild type accumulated, indicating that the function of PgpH may be to adjust cellular (p)ppGpp levels during low-temperature growth. The cld-14
pgpH

+

complemented strain was able to grow at a low temperature, like the parent strain, providing direct evidence that the activity of PgpH is important in low-temperature adaptation. Because of its predicted membrane location, PgpH may play a critical role in sensing the environmental temperature and altering cellular (p)ppGpp levels to allow the organism to adapt to low temperatures.
Development, Evaluation, and Standardization of a Real-Time TaqMan Reverse Transcription-PCR Assay for Quantification of Hepatitis A Virus in Clinical and Shellfish Samples
Authors: Costafreda M. Isabel , Bosch Albert , Pintó Rosa M. 
Published: June 2006

ABSTRACT
A standardized real-time reverse transcription-PCR (RT-PCR) assay has been developed for an accurate estimation of the number of genome copies of hepatitis A virus (HAV) in clinical and shellfish samples. Real-time procedures were based on the amplification of a fragment of the highly conserved 5′ noncoding region and detection through an internal fluorescent probe, including TaqMan and beacon chemistries, in one- and two-step RT-PCR formats. The best performance in terms of sensitivity and reproducibility was achieved by a one-step TaqMan RT-PCR, with a sensitivity enabling the detection of 0.05 infectious unit and 10 copies of a single-stranded RNA (ssRNA) synthetic transcript. Standard reagents, such as a mengovirus strain and an ssRNA transcript, were employed as controls of nucleic acid extraction and RT-PCR, respectively. The test proved to be highly specific after a broad panel of enteric viruses was tested. Sequence alignment of target regions of the primers and probe proved them to be adequate for the quantification of all HAV genotypes. In addition, a quasispecies analysis of the mutant spectrum indicated that these regions are not prone to variability, thus confirming their robustness.
Evaluation of Two Methods of Determining the Efficacies of Two Alcohol-Based Hand Rubs for Surgical Hand Antisepsis
Authors: Kampf Günter , Ostermeyer Christiane , Heeg Peter , Paulson Daryl 
Published: June 2006

ABSTRACT

The antimicrobial efficacies of preparations for surgical hand antisepsis can be determined according to a European standard (prEN 12791 [EN]) and a U.S. standard (tentative final monograph for health care antiseptic drug products [TFM]). The U.S. method differs in the product application mode (hands and lower forearms, versus hands only in EN), the number of applications (11 over 5 days, versus a single application in EN), the sampling times (0, 3, and 6 h after application, versus 0 and 3 h in EN), the sampling methods (glove juice versus fingertip sampling in EN), and the outcome requirements (absolute bacterial reduction factor [RF], versus noninferiority to reference treatment in EN). We have studied the efficacies of two hand rubs according to both methods. One hand rub was based on 80% ethanol and applied for 2 min, and the other one was based on 45% propan-2-ol, 30% propan-1-ol, and 0.2% mecetronium etilsulfate and applied for 1.5 min. The ethanol-based hand rub was equally effective as the 3-min reference disinfection of prEN 12791 in both the immediate (RFs, 2.97 ± 0.89 versus 2.92 ± 1.03, respectively) and sustained (RFs, 2.20 ± 1.07 versus 2.47 ± 1.25, respectively) effects. According to TFM, the immediate effects were 2.99 log
10
(day 1), 3.00 log
10
(day 2), and 3.43 log
10
(day 5), and bacterial counts were still below baseline after 6 h. The propanol-based hand rub was even more effective than the reference disinfection of prEN 12791 in both the immediate (RFs, 2.35 ± 0.99 versus 1.86 ± 0.87, respectively) and sustained (RFs, 2.17 ± 1.00 versus 1.50 ± 1.26, respectively) effects. According to TFM, the immediate effects were 2.82 log
10
(day 1), 3.29 log
10
(day 2), and 3.25 log
10
(day 5), and bacterial counts were still below baseline after 6 h. Some formulations have been reported to meet the efficacy requirements of one of the methods but not those of the other. That is why we conclude that, despite our results, meeting the efficacy requirements of one test method does not allow the claim that the requirements of the other test method are also met.