bluuebunny/crossref_metadata_2025_split huggingface dataset:
Trends in Antimicrobial Resistance among Urinary Tract Infection Isolates of
Escherichia coli
from Female Outpatients in the United States
Authors: Karlowsky James A. , Kelly Laurie J. , Thornsberry Clyde , Jones Mark E. , Sahm Daniel F. 
Published: July 2002

ABSTRACT

The Infectious Diseases Society of America advocates trimethoprim-sulfamethoxazole (SXT) as initial therapy for females with acute uncomplicated bacterial cystitis in settings where the prevalence of SXT resistance does not exceed 10 to 20%. To determine trends in the activities of SXT, ampicillin, ciprofloxacin, and nitrofurantoin among urine isolates of
Escherichia coli
from female outpatients, susceptibility testing data from The Surveillance Network (TSN) Database-USA (
n
= 286,187) from 1995 to 2001 were analyzed. Resistance rates among
E. coli
isolates to ampicillin (range, 36.0 to 37.4% per year), SXT (range, 14.8 to 17.0%), ciprofloxacin (range, 0.7 to 2.5%), and nitrofurantoin (range, 0.4 to 0.8%) varied only slightly over this 7-year period. Ciprofloxacin was the only agent studied that demonstrated a consistent stepwise increase in resistance from 1995 (0.7%) to 2001 (2.5%). In 2001, SXT resistance among
E. coli
isolates was >10% in all nine U.S. Bureau of the Census regions. At institutions testing ≥100 urinary isolates of
E. coli
(
n
= 126) in 2001, ampicillin (range, 27.3 to 98.8%) and SXT (range, 7.5 to 47.1%) resistance rates varied widely while ciprofloxacin (range, 0 to 12.9%) and nitrofurantoin (range, 0 to 2.8%) resistance rates were more consistent. In 2001, the most frequent coresistant phenotypes were resistance to ampicillin and SXT (12.0% of all isolates; 82.3% of coresistant isolates) and resistance to ampicillin, ciprofloxacin, and SXT (1.4% of all isolates; 9.9% of coresistant isolates). Coresistance less frequently included resistance to nitrofurantoin (3.5% of coresistant isolates) than resistance to ciprofloxacin (15.8%), SXT (95.7%), and ampicillin (98.1%). In conclusion, among urinary isolates of
E. coli
from female outpatients in the United States, national resistance rates to SXT were relatively consistent (14.8 to 17.0%) from 1995 to 2001 but demonstrated considerable regional and institutional variation in 2001. Therapies other than SXT may need to be considered in some locations.
Efficacy of Caspofungin Alone and in Combination with Voriconazole in a Guinea Pig Model of Invasive Aspergillosis
Authors: Kirkpatrick William R. , Perea Sofia , Coco Brent J. , Patterson Thomas F. 
Published: July 2002

ABSTRACT

The antifungal activity of caspofungin acetate (CAS) alone and in combination with voriconazole (VRC) was evaluated in an immunosuppressed transiently neutropenic guinea pig model of invasive aspergillosis. Guinea pigs were immunosuppressed with triamcinolone at 20 mg/kg of body weight/day subcutaneously beginning 4 days prior to lethal intravenous challenge with
Aspergillus fumigatus
and were made temporarily neutropenic with cyclophosphamide administered at 150 mg/kg intraperitoneally (i.p.) 1 day prior to challenge. Therapy with i.p. CAS at 1 and 2.5 mg/kg/day (with and without oral VRC at 5 mg/kg/day), oral VRC at 5 mg/kg/day, or i.p. amphotericin B (AMB) at 1.25 mg/kg/day was begun 24 h after challenge and was continued for 5 days. Mortality occurred in 12 of 12 untreated controls, whereas mortality occurred in 4 of 12 and 6 of 12 guinea pigs treated with CAS at 1 and 2.5 mg/kg/day, respectively, and in 3 of 12 guinea pigs treated with AMB. No mortality occurred among animals treated with CAS at 1 mg/kg/day plus VRC at 5 mg/kg/day, CAS at 2.5 mg/kg/day plus VRC at 5 mg/kg/day, or VRC at 5 mg/kg/day alone. Both CAS regimens increased the survival times and reduced the colony counts in tissue compared with those for the controls. Treatment with VRC and AMB significantly reduced the colony counts in the tissues of selected animals compared with those in the tissues of the controls. Treatment with VRC and AMB also resulted in reductions in colony counts in tissues compared with those in the tissues of animals treated with CAS (the difference was not statistically significant) and improved the survival times but did not sterilize tissues. Combination therapies with CAS plus VRC at either dose reduced colony counts in tissues 1,000-fold over those for the controls and were the only regimens that significantly reduced the numbers of positive cultures. The combinations of CAS plus VRC were highly effective in this model and should be further evaluated for use against invasive aspergillosis.
DNA Gyrase and Topoisomerase IV Mutations Associated with Fluoroquinolone Resistance in
Proteus mirabilis
Authors: Weigel L. M. , Anderson G. J. , Tenover F. C. 
Published: July 2002

ABSTRACT

Mutations associated with fluoroquinolone resistance in clinical isolates of
Proteus mirabilis
were determined by genetic analysis of the quinolone resistance-determining region (QRDR) of
gyrA
,
gyrB
,
parC
, and
parE
. This study included the
P. mirabilis
type strain ATCC 29906 and 29 clinical isolates with reduced susceptibility (MIC, 0.5 to 2 μg/ml) or resistance (MIC, ≥4 μg/ml) to ciprofloxacin. Susceptibility profiles for ciprofloxacin, clinafloxacin, gatifloxacin, gemifloxacin, levofloxacin, moxifloxacin, and trovafloxacin were correlated with amino acid changes in the QRDRs. Decreased susceptibility and resistance were associated with double mutations involving both
gyrA
(S83R or -I) and
parC
(S80R or -I). Among these double mutants, MICs of ciprofloxacin varied from 1 to 16 μg/ml, indicating that additional factors, such as drug efflux or porin changes, also contribute to the level of resistance. For ParE, a single conservative change of V364I was detected in seven strains. An unexpected result was the association of
gyrB
mutations with high-level resistance to fluoroquinolones in 12 of 20 ciprofloxacin-resistant isolates. Changes in GyrB included S464Y (six isolates), S464F (three isolates), and E466D (two isolates). A three-nucleotide insertion, resulting in an additional lysine residue between K455 and A456, was detected in
gyrB
of one strain. Unlike any other bacterial species analyzed to date, mutation of
gyrB
appears to be a frequent event in the acquisition of fluoroquinolone resistance among clinical isolates of
P. mirabilis
.
In Vitro and In Vivo Activities of Tigecycline (GAR-936), Daptomycin, and Comparative Antimicrobial Agents against Glycopeptide-IntermediateStaphylococcus aureusand Other Resistant Gram-Positive Pathogens
Authors: Petersen Peter J. , Bradford Patricia A. , Weiss William J. , Murphy Timothy M. , Sum P. E. , Projan Steven J. 
Published: July 2002

ABSTRACTTigecycline (GAR-936) and daptomycin are potent antibacterial compounds in advanced stages of clinical trials. These novel agents target multiply resistant pathogenic bacteria. Daptomycin is principally active against gram-positive bacteria, while tigecycline has broad-spectrum activity. When tested by the standard protocols of the National Committee for Clinical Laboratory Standards in Mueller-Hinton broth II, tigecycline was more active than daptomycin (MICs at which 90% of isolates tested are inhibited, 0.12 to 1 and 0.5 to 16 μg/ml, respectively) against staphylococcal, enterococcal, and streptococcal pathogens. Daptomycin demonstrated a stepwise increase in activity corresponding to an increase in the supplemental concentration of calcium. When tested in base Mueller-Hinton broth supplemented with 50 mg of calcium per liter, daptomycin demonstrated improved activity (MIC90s, 0.015 to 4 μg/ml). The activity of daptomycin, however, equaled that of tigecycline against the glycopeptide-intermediateStaphylococcus aureus(GISA) strains only when the test medium was supplemented with excess calcium (75 mg/liter). Tigecycline and daptomycin demonstrated in vivo efficacies against GISA, methicillin-resistantS. aureus, and methicillin-susceptibleS. aureusstrains in an intraperitoneal systemic murine infection model. These data suggest that tigecycline and daptomycin may offer therapeutic options against clinically relevant resistant pathogens for which current alternatives for treatment are limited.
The AcrAB-TolC Efflux Pump Contributes to Multidrug Resistance in the Nosocomial Pathogen
Enterobacter aerogenes
Authors: Pradel Elizabeth , Pagès Jean-Marie 
Published: July 2002

ABSTRACT

We identified the genes encoding the AcrA-AcrB-TolC efflux pump in
Enterobacter aerogenes
and constructed
acrAB
and
tolC
mutants from a multidrug-resistant isolate. Both derivatives were more susceptible to antibiotics than the parental strain. Sequence analysis and complementation experiments revealed that the multidrug-resistant isolate is an
acrR
mutant.
gyrA
Polymorphism in
Campylobacter jejuni
: Detection of
gyrA
Mutations in 162
C. jejuni
Isolates by Single-Strand Conformation Polymorphism and DNA Sequencing
Authors: Hakanen Antti , Jalava Jari , Kotilainen Pirkko , Jousimies-Somer Hannele , Siitonen Anja , Huovinen Pentti 
Published: July 2002

ABSTRACT

Mutations in the quinolone resistance-determining region of the
gyrA
gene from 138 ciprofloxacin-resistant (MIC, ≥4 μg/ml) and 24 ciprofloxacin-susceptible (MIC, ≤1 μg/ml) clinical
Campylobacter jejuni
isolates were subjected to single-strand conformation polymorphism analysis and sequencing. All of the isolates could be assigned to three genotypic clusters based on silent mutations. All resistant isolates had a point mutation at codon 86.
Novel Complex
sul1
-Type Integron in
Escherichia coli
Carrying
bla
CTX-M-9
Authors: Sabaté Montserrat , Navarro Ferran , Miró Elisenda , Campoy Susana , Mirelis Beatriz , Barbé Jordi , Prats Guillem 
Published: July 2002

ABSTRACT

For the present report, a novel complex class 1 integron, In60, was characterized. Part of this integron includes the
bla
CTX-M-9
gene and its downstream nucleotide sequence, which shares 81% and 78% nucleotide identity with those of
kluA-1
β-lactamase and
orf3
of
K. ascorbata
, respectively. Furthermore, a new insertion sequence, IS
3000
, has been found in In60. PCR analysis indicates that integron In60 is present in 33 of 34 nonclonal enterobacterial isolates carrying the putative β-lactamase CTX-M-9.
Transmission Electron Microscopic Study of Antibiotic Action on
Klebsiella pneumoniae
Biofilm
Authors: Zahller Jeff , Stewart Philip S. 
Published: July 2002

ABSTRACT

The penetration of ampicillin and ciprofloxacin through biofilms formed by
Klebsiella pneumoniae
was confirmed by transmission electron microscopic observation of antibiotic-affected cells at the distal edge of the biofilm. Because the bacteria nevertheless survived antibiotic treatment, some protective mechanism other than inadequate penetration must have been at work in the biofilm.
Differential Ability of Genotypes of 2,4-Diacetylphloroglucinol-Producing
Pseudomonas fluorescens
Strains To Colonize the Roots of Pea Plants
Authors: Landa Blanca B. , Mavrodi Olga V. , Raaijmakers Jos M. , McSpadden Gardener Brian B. , Thomashow Linda S. , Weller David M. 
Published: July 2002

ABSTRACT

Indigenous populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing fluorescent
Pseudomonas
spp. that occur naturally in suppressive soils are an enormous resource for improving biological control of plant diseases. Over 300 isolates of 2,4-DAPG-producing fluorescent
Pseudomonas
spp. were isolated from the rhizosphere of pea plants grown in soils that had undergone pea or wheat monoculture and were suppressive to
Fusarium
wilt or take-all, respectively. Representatives of seven genotypes, A, D, E, L, O, P, and Q, were isolated from both soils and identified by whole-cell repetitive sequence-based PCR (rep-PCR) with the BOXA1R primer, increasing by three (O, P, and Q) the number of genotypes identified previously among a worldwide collection of 2,4-DAPG producers. Fourteen isolates representing eight different genotypes were tested for their ability to colonize the rhizosphere of pea plants. Population densities of strains belonging to genotypes D and P were significantly greater than the densities of other genotypes and remained above log 6.0 CFU (g of root)
−1
over the entire 15-week experiment. Genetic profiles generated by rep-PCR or restriction fragment length polymorphism analysis of the 2,4-DAPG biosynthetic gene
phlD
were predictive of the rhizosphere competence of the introduced 2,4-DAPG-producing strains.
Analysis of Bacterial Community Composition by Oligonucleotide Fingerprinting of rRNA Genes
Authors: Valinsky Lea , Della Vedova Gianluca , Scupham Alexandra J. , Alvey Sam , Figueroa Andres , Yin Bei , Hartin R. Jack , Chrobak Marek , Crowley David E. , Jiang Tao , Borneman James 
Published: July 2002

ABSTRACT

One of the first steps in characterizing an ecosystem is to describe the organisms inhabiting it. For microbial studies, experimental limitations have hindered the ability to depict diverse communities. Here we describe oligonucleotide fingerprinting of rRNA genes (OFRG), a method that permits identification of arrayed rRNA genes (rDNA) through a series of hybridization experiments using small DNA probes. To demonstrate this strategy, we examined the bacteria inhabiting two different soils. Analysis of 1,536 rDNA clones revealed 766 clusters grouped into five major taxa:
Bacillus
,
Actinobacteria
,
Proteobacteria
, and two undefined assemblages. Soil-specific taxa were identified and then independently confirmed through cluster-specific PCR of the original soil DNA. Near-species-level resolution was obtained by this analysis as clones with average sequence identities of 97% were grouped in the same cluster. A comparison of these OFRG results with the results obtained in a denaturing gradient gel electrophoresis analysis of the same two soils demonstrated the significance of this methodological advance. OFRG provides a cost-effective means to extensively analyze microbial communities and should have applications in medicine, biotechnology, and ecosystem studies.
Cloning and Heterologous Expression of an Enantioselective Amidase from
Rhodococcus erythropolis
Strain MP50
Authors: Trott Sandra , Bürger Sibylle , Calaminus Carsten , Stolz Andreas 
Published: July 2002

ABSTRACT

The gene for an enantioselective amidase was cloned from
Rhodococcus erythropolis
MP50, which utilizes various aromatic nitriles via a nitrile hydratase/amidase system as nitrogen sources. The gene encoded a protein of 525 amino acids which corresponded to a protein with a molecular mass of 55.5 kDa. The deduced complete amino acid sequence showed homology to other enantioselective amidases from different bacterial genera. The nucleotide sequence approximately 2.5 kb upstream and downstream of the amidase gene was determined, but no indications for a structural coupling of the amidase gene with the genes for a nitrile hydratase were found. The amidase gene was carried by an approximately 40-kb circular plasmid in
R. erythropolis
MP50. The amidase was heterologously expressed in
Escherichia coli
and shown to hydrolyze 2-phenylpropionamide, α-chlorophenylacetamide, and α-methoxyphenylacetamide with high enantioselectivity; mandeloamide and 2-methyl-3-phenylpropionamide were also converted, but only with reduced enantioselectivity. The recombinant
E. coli
strain which synthesized the amidase gene was shown to grow with organic amides as nitrogen sources. A comparison of the amidase activities observed with whole cells or cell extracts of the recombinant
E. coli
strain suggested that the transport of the amides into the cells becomes the rate-limiting step for amide hydrolysis in recombinant
E. coli
strains.
Identification of
glyA
(Encoding Serine Hydroxymethyltransferase) and Its Use Together with the Exporter ThrE To Increase
l
-Threonine Accumulation by
Corynebacterium glutamicum
Authors: Simic Petra , Willuhn Juliane , Sahm Hermann , Eggeling Lothar 
Published: July 2002

ABSTRACT

l
-Threonine can be made by the amino acid-producing bacterium
Corynebacterium glutamicum
. However, in the course of this process, some of the
l
-threonine is degraded to glycine. We detected an aldole cleavage activity of
l
-threonine in crude extracts with an activity of 2.2 nmol min
−1
(mg of protein)
−1
. In order to discover the molecular reason for this activity, we cloned
glyA
, encoding serine hydroxymethyltransferase (SHMT). By using affinity-tagged
glyA
, SHMT was isolated and its substrate specificity was determined. The aldole cleavage activity of purified SHMT with
l
-threonine as the substrate was 1.3 μmol min
−1
(mg of protein)
−1
, which was 4% of that with
l
-serine as substrate. Reduction of SHMT activity in vivo was obtained by placing the essential
glyA
gene in the chromosome under the control of P

tac

, making
glyA
expression isopropylthiogalactopyranoside dependent. In this way, the SHMT activity in an
l
-threonine producer was reduced to 8% of the initial activity, which led to a 41% reduction in glycine, while
l
-threonine was simultaneously increased by 49%. The intracellular availability of
l
-threonine to aldole cleavage was also reduced by overexpressing the
l
-threonine exporter
thrE
. In
C. glutamicum
DR-17, which overexpresses
thrE
, accumulation of 67 mM instead of 49 mM
l
-threonine was obtained. This shows that the potential for amino acid formation can be considerably improved by reducing its intracellular degradation and increasing its export.
Prevalence and Fingerprinting of
Listeria monocytogenes
Strains Isolated from Raw Whole Milk in Farm Bulk Tanks and in Dairy Plant Receiving Tanks
Authors: Waak Elisabet , Tham Wilhelm , Danielsson-Tham Marie-Louise 
Published: July 2002

ABSTRACT

The incidence of
Listeria
species in raw whole milk from farm bulk tanks and from raw milk in storage at a Swedish dairy plant was studied.
Listeria monocytogenes
was found in 1.0% and
Listeria innocua
was found in 2.3% of the 294 farm bulk tank (farm tank) milk specimens. One farm tank specimen contained 60 CFU of
L. monocytogenes
ml
−1
.
L. monocytogenes
was detected in 19.6% and
L. innocua
was detected in 8.5% of the milk specimens from the silo receiving tanks at the dairy (dairy silos). More dairy silo specimens were positive for both
Listeria
species during winter than during summer. Restriction enzyme analysis and pulsed-field gel electrophoresis were applied to 65 isolates of
L. monocytogenes
, resulting in 16 different clonal types. Two clonal types were shared by the farm tank milk and the dairy silo milk. All except one clonal type belonged to serovar 1/2a. In the dairy silo milk five clonal types were found more frequently and for a longer period than the others. No
Listeria
species were found in any other samples from the plant.
Technical-Scale Production of Cyanophycin with Recombinant Strains of
Escherichia coli
Authors: Frey Kay M. , Oppermann-Sanio Fred B. , Schmidt Holger , Steinbüchel Alexander 
Published: July 2002

ABSTRACT

By the use of
Escherichia coli
DH1 harboring
cphA
from
Synechocystis
sp. strain PCC6803, large-scale production of cyanophycin at 30- and 500-liter culture volumes was established. Transcription of
cphA
was controlled by the thermosensitive cI857 repressor, which enabled induction of
cphA
by a simple temperature shift in the culture fluid. Maximum cyanophycin cell content of up to 24% (wt/wt) of cellular dry matter was obtained by induction in the early exponential growth phase and cultivation of the cells in terrific broth complex medium. Synthesis of cyanophycin was found to be strongly dependent on the presence of complex components, and in mineral salts medium the cells synthesized and accumulated cyanophycin only if Casamino Acids were added. Cultivations were done at the 500-liter scale, allowing the provision of cell mass for the preparation of cyanophycin at the kilogram scale. Isolation of cyanophycin was achieved by a new acid extraction procedure which allowed large-scale purification of the polyamide from whole cells.
Expression of a Fungal Hydrophobin in theSaccharomyces cerevisiaeCell Wall: Effect on Cell Surface Properties and Immobilization
Authors: Nakari-Setälä Tiina , Azeredo Joana , Henriques Mariana , Oliveira Rosário , Teixeira José , Linder Markus , Penttilä Merja 
Published: July 2002

ABSTRACTThe aim of this work was to modify the cell surface properties ofSaccharomyces cerevisiaeby expression of the HFBI hydrophobin of the filamentous fungusTrichoderma reeseion the yeast cell surface. The second aim was to study the immobilization capacity of the modified cells. Fusion to the Flo1p flocculin was used to target the HFBI moiety to the cell wall. Determination of cell surface characteristics with contact angle and zeta potential measurements indicated that HFBI-producing cells are more apolar and slightly less negatively charged than the parent cells. Adsorption of the yeast cells to different commercial supports was studied. A twofold increase in the binding affinity of the hydrophobin-producing yeast to hydrophobic silicone-based materials was observed, while no improvement in the interaction with hydrophilic carriers could be seen compared to that of the parent cells. Hydrophobic interactions between the yeast cells and the support are suggested to play a major role in attachment. Also, a slight increase in the initial adsorption rate of the hydrophobin yeast was observed. Furthermore, due to the engineered cell surface, hydrophobin-producing yeast cells were efficiently separated in an aqueous two-phase system by using a nonionic polyoxyethylene detergent, C12-18EO5.
Mucosa-Associated Bacteria in the Human Gastrointestinal Tract Are Uniformly Distributed along the Colon and Differ from the Community Recovered from Feces
Authors: Zoetendal Erwin G. , von Wright Atte , Vilpponen-Salmela Terttu , Ben-Amor Kaouther , Akkermans Antoon D. L. , de Vos Willem M. 
Published: July 2002

ABSTRACT

The human gastrointestinal (GI) tract harbors a complex community of bacterial cells in the mucosa, lumen, and feces. Since most attention has been focused on bacteria present in feces, knowledge about the mucosa-associated bacterial communities in different parts of the colon is limited. In this study, the bacterial communities in feces and biopsy samples from the ascending, transverse, and descending colons of 10 individuals were analyzed by using a 16S rRNA approach. Flow cytometric analysis indicated that 10
5
to 10
6
bacteria were present in the biopsy samples. To visualize the diversity of the predominant and the
Lactobacillus
group community, denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene amplicons was performed. DGGE analysis and similarity index comparisons demonstrated that the predominant mucosa-associated bacterial community was host specific and uniformly distributed along the colon but significantly different from the fecal community (
P
< 0.01). The
Lactobacillus
group-specific profiles were less complex than the profiles reflecting the predominant community. For 6 of the 10 individuals the community of
Lactobacillus
-like bacteria in the biopsy samples was similar to that in the feces. Amplicons having 99% sequence similarity to the 16S ribosomal DNA of
Lactobacillus gasseri
were detected in the biopsy samples of nine individuals. No significant differences were observed between healthy and diseased individuals. The observed host-specific DGGE profiles of the mucosa-associated bacterial community in the colon support the hypothesis that host-related factors are involved in the determination of the GI tract microbial community.