bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prospective Survey of β-Lactamases Produced by Ceftazidime- Resistant
Pseudomonas aeruginosa
Isolated in a French Hospital in 2000
Authors: De Champs Christophe , Poirel Laurent , Bonnet Richard , Sirot Danielle , Chanal Catherine , Sirot Jacques , Nordmann Patrice 
Published: October 2002

ABSTRACT

In 2000, at the Université d'Auvergne teaching hospital in Clermont-Ferrand, France, 44 (6.2%) strains of
Pseudomonas aeruginosa
were found to be resistant to ceftazidime. After genotyping, 34 strains were selected. Nine had an additional β-lactamase: OXA-21 (
n
= 6), PSE-1 (CARB-2) (
n
= 2), or PER-1 (
n
= 1). Ceftazidime resistance was related solely to the overproduction of the cephalosporinase in 30 strains. Sequencing of five
bla
AmpC
genes encoding cephalosporinases with different pIs showed 99% identity with the
ampC
gene of
P. aeruginosa
PAO1.
Clinical Isolates of
Staphylococcus aureus
with Ribosomal Mutations Conferring Resistance to Macrolides
Authors: Prunier Anne-Laure , Malbruny Brigitte , Tandé Didier , Picard Bertrand , Leclercq Roland 
Published: October 2002

ABSTRACT

Six strains of
Staphylococcus aureus
isolated from cystic fibrosis patients after treatment with azithromycin were cross-resistant to azithromycin and erythromycin. None of the isolates contained
erm
or
msr
(A) genes, but they all carried either A2058G/U or A2059G mutations within the
rrl
genes, with a majority of the rRNA copies bearing the mutation. One strain displayed an additional mutation in the
rplV
gene, encoding the L22 ribosomal protein.
In Vitro and In Vivo Antibacterial Activities of DW286, a New Fluoronaphthyridone Antibiotic
Authors: Yun Hee-Jeong , Min Yu-Hong , Lim Jung-A , Kang Jin-Wook , Kim So-Young , Kim Mi-Jeong , Jeong Jae-Hee , Choi Yun-Jeong , Kwon Hyun-Jin , Jung Yong-Ho , Shim Mi-Ja , Choi Eung-Chil 
Published: October 2002

ABSTRACT

The in vitro and in vivo activities of DW286, a novel fluoronaphthyridone with potent antibacterial activity, were compared with those of ciprofloxacin, gemifloxacin, sparfloxacin, and trovafloxacin. Against gram-positive bacteria, such as
Staphylococcus aureus
,
Staphylococcus epidermidis
,
Streptococcus pneumoniae
, and
Enterococcus faecalis
, the in vitro activity of DW286 was stronger than that of any other reference antibiotic. Against gram-negative bacteria, the activity of DW286 was similar to those of trovafloxacin and gemifloxacin but was weaker than that of ciprofloxacin. In a mouse systemic infection caused by three
S. aureus
strains, including methicillin-resistant
S. aureus
and quinolone-resistant
S. aureus
(QRSA), DW286 demonstrated the most potent activity, as found in vitro. Specially, DW286 is ≥8-fold more active against QRSA than the other fluoroquinolones. And the 50% protective doses for DW286 were correspondent with the in vitro activities.
Comparative Activities of the Oxazolidinone AZD2563 and Linezolid against Selected Recent North American Isolates of
Streptococcus pneumoniae
Authors: Baum Sue E. , Crawford Sharon A. , McElmeel M. L. , Whitney Cynthia G. , Jorgensen James H. 
Published: October 2002

ABSTRACT

The activity of AZD2563 against 250 highly resistant pneumococci and 267 drug-susceptible isolates was determined. The AZD2563 MICs for 50 and 90% of the strains tested were 1 and 2 μg/ml and 0.5 and 1 μg/ml, respectively, for the two isolate groups. These MICs were within 1 log
2
dilution of those of linezolid.
Homologs of the Rml Enzymes from
Salmonella enterica
Are Responsible for dTDP-β-
l
-Rhamnose Biosynthesis in the Gram-Positive Thermophile
Aneurinibacillus thermoaerophilus
DSM 10155
Authors: Graninger Michael , Kneidinger Bernd , Bruno Katharina , Scheberl Andrea , Messner Paul 
Published: October 2002

ABSTRACT

The glycan chains of the surface layer (S-layer) glycoprotein from the gram-positive, thermophilic bacterium
Aneurinibacillus
(formerly
Bacillus
)
thermoaerophilus
strain DSM 10155 are composed of
l
-rhamnose- and
d
-
glycero
-
d
-
manno
-heptose-containing disaccharide repeating units which are linked to the S-layer polypeptide via core structures that have variable lengths and novel O-glycosidic linkages. In this work we investigated the enzymes involved in the biosynthesis of thymidine diphospho-
l
-rhamnose (dTDP-
l
-rhamnose) and their specific properties. Comparable to lipopolysaccharide O-antigen biosynthesis in gram-negative bacteria, dTDP-
l
-rhamnose is synthesized in a four-step reaction sequence from dTTP and glucose 1-phosphate by the enzymes glucose-1-phosphate thymidylyltransferase (RmlA), dTDP-
d
-glucose 4,6-dehydratase (RmlB), dTDP-4-dehydrorhamnose 3,5-epimerase (RmlC), and dTDP-4-dehydrorhamnose reductase (RmlD). The rhamnose biosynthesis operon from
A. thermoaerophilus
DSM 10155 was sequenced, and the genes were overexpressed in
Escherichia coli
. Compared to purified enterobacterial Rml enzymes, the enzymes from the gram-positive strain show remarkably increased thermostability, a property which is particularly interesting for high-throughput screening and enzymatic synthesis. The closely related strain
A. thermoaerophilus
L420-91
T
produces
d
-rhamnose- and 3-acetamido-3,6-dideoxy-
d
-galactose-containing S-layer glycan chains. Comparison of the enzyme activity patterns in
A. thermoaerophilus
strains DSM 10155 and L420-91
T
for
l
-rhamnose and
d
-rhamnose biosynthesis indicated that the enzymes are differentially expressed during S-layer glycan biosynthesis and that
A. thermoaerophilus
L420-91
T
is not able to synthesize dTDP-
l
-rhamnose. These findings confirm that in each strain the enzymes act specifically on S-layer glycoprotein glycan formation.
Identification, Characterization, and Regulation of a Cluster of Genes Involved in Carbapenem Biosynthesis in
Photorhabdus luminescens
Authors: Derzelle Sylviane , Duchaud Eric , Kunst Frank , Danchin Antoine , Bertin Philippe 
Published: October 2002

ABSTRACT

The luminescent entomopathogenic bacterium
Photorhabdus luminescens
produces several yet-uncharacterized broad-spectrum antibiotics. We report the identification and characterization of a cluster of eight genes (named
cpmA
to
cpmH
) responsible for the production of a carbapenem-like antibiotic in strain TT01 of
P. luminescens
. The
cpm
cluster differs in several crucial aspects from other
car
operons. The level of
cpm
mRNA peaks during exponential phase and is regulated by a Rap/Hor homolog identified in the
P. luminescens
genome. Marker-exchange mutagenesis of this gene in the entomopathogen decreased antibiotic production. The
luxS
-like signaling mechanism of quorum sensing also plays a role in the regulation of the
cpm
operon. Indeed,
luxS
, which is involved in the production of a newly identified autoinducer, is responsible for repression of
cpm
gene expression at the end of the exponential growth phase. The importance of this carbapenem production in the ecology of
P. luminescens
is discussed.
Comparison of In Vitro Cell Culture and a Mouse Assay for Measuring Infectivity of
Cryptosporidium parvum
Authors: Rochelle Paul A. , Marshall Marilyn M. , Mead Jan R. , Johnson Anne M. , Korich Dick G. , Rosen Jeffrey S. , De Leon Ricardo 
Published: October 2002

ABSTRACT

In vitro cell cultures were compared to neonatal mice for measuring the infectivity of five genotype 2 isolates of
Cryptosporidium parvum
. Oocyst doses were enumerated by flow cytometry and delivered to animals and cell monolayers by using standardized procedures. Each dose of oocysts was inoculated into up to nine replicates of 9 to 12 mice or 6 to 10 cell culture wells. Infections were detected by hematoxylin and eosin staining in CD-1 mice, by reverse transcriptase PCR in HCT-8 and Caco-2 cells, and by immunofluorescence microscopy in Madin-Darby canine kidney (MDCK) cells. Infectivity was expressed as a logistic transformation of the proportion of animals or cell culture wells that developed infection at each dose. In most instances, the slopes of the dose-response curves were not significantly different when we compared the infectivity models for each isolate. The 50% infective doses for the different isolates varied depending on the method of calculation but were in the range from 16 to 347 oocysts for CD-1 mice and in the ranges from 27 to 106, 31 to 629, and 13 to 18 oocysts for HCT-8, Caco-2, and MDCK cells, respectively. The average standard deviations for the percentages of infectivity for all replicates of all isolates were 13.9, 11.5, 13.2, and 10.7% for CD-1 mice, HCT-8 cells, Caco-2 cells, and MDCK cells, respectively, demonstrating that the levels of variability were similar in all assays. There was a good correlation between the average infectivity for HCT-8 cells and the results for CD-1 mice across all isolates for untreated oocysts (
r
= 0.85,
n
= 25) and for oocysts exposed to ozone and UV light (
r
= 0.89,
n
= 29). This study demonstrated that in vitro cell culture was equivalent to the “gold standard,” mouse infectivity, for measuring the infectivity of
C. parvum
and should therefore be considered a practical and accurate alternative for assessing oocyst infectivity and inactivation. However, the high levels of variability displayed by all assays indicated that infectivity and disinfection experiments should be limited to discerning relatively large differences.
Association of Microbial Community Composition and Activity with Lead, Chromium, and Hydrocarbon Contamination
Authors: Shi W. , Becker J. , Bischoff M. , Turco R. F. , Konopka A. E. 
Published: October 2002

ABSTRACT

Microbial community composition and activity were characterized in soil contaminated with lead (Pb), chromium (Cr), and hydrocarbons. Contaminant levels were very heterogeneous and ranged from 50 to 16,700 mg of total petroleum hydrocarbons (TPH) kg of soil
−1
, 3 to 3,300 mg of total Cr kg of soil
−1
, and 1 to 17,100 mg of Pb kg of soil
−1
. Microbial community compositions were estimated from the patterns of phospholipid fatty acids (PLFA); these were considerably different among the 14 soil samples. Statistical analyses suggested that the variation in PLFA was more correlated with soil hydrocarbons than with the levels of Cr and Pb. The metal sensitivity of the microbial community was determined by extracting bacteria from soil and measuring [
3
H]leucine incorporation as a function of metal concentration. Six soil samples collected in the spring of 1999 had IC
50
values (the heavy metal concentrations giving 50% reduction of microbial activity) of approximately 2.5 mM for CrO
4
2−
and 0.01 mM for Pb
2+
. Much higher levels of Pb were required to inhibit [
14
C]glucose mineralization directly in soils. In microcosm experiments with these samples, microbial biomass and the ratio of microbial biomass to soil organic C were not correlated with the concentrations of hydrocarbons and heavy metals. However, microbial C respiration in samples with a higher level of hydrocarbons differed from the other soils no matter whether complex organic C (alfalfa) was added or not. The ratios of microbial C respiration to microbial biomass differed significantly among the soil samples (
P
< 0.05) and were relatively high in soils contaminated with hydrocarbons or heavy metals. Our results suggest that the soil microbial community was predominantly affected by hydrocarbons.
Biodesulfurization of Naphthothiophene and Benzothiophene through Selective Cleavage of Carbon-Sulfur Bonds by
Rhodococcus
sp. Strain WU-K2R
Authors: Kirimura Kohtaro , Furuya Toshiki , Sato Rika , Ishii Yoshitaka , Kino Kuniki , Usami Shoji 
Published: October 2002

ABSTRACT

Naphtho[2,1-
b
]thiophene (NTH) is an asymmetric structural isomer of dibenzothiophene (DBT), and in addition to DBT derivatives, NTH derivatives can also be detected in diesel oil following hydrodesulfurization treatment.
Rhodococcus
sp. strain WU-K2R was newly isolated from soil for its ability to grow in a medium with NTH as the sole source of sulfur, and growing cells of WU-K2R degraded 0.27 mM NTH within 7 days. WU-K2R could also grow in the medium with NTH sulfone, benzothiophene (BTH), 3-methyl-BTH, or 5-methyl-BTH as the sole source of sulfur but could not utilize DBT, DBT sulfone, or 4,6-dimethyl-DBT. On the other hand, WU-K2R did not utilize NTH or BTH as the sole source of carbon. By gas chromatography-mass spectrometry analysis, desulfurized NTH metabolites were identified as NTH sulfone, 2′-hydroxynaphthylethene, and naphtho[2,1-
b
]furan. Moreover, since desulfurized BTH metabolites were identified as BTH sulfone, benzo[
c
][1,2]oxathiin
S
-oxide, benzo[
c
][1,2]oxathiin
S
,
S
-dioxide,
o
-hydroxystyrene, 2-(2′-hydroxyphenyl)ethan-1-al, and benzofuran, it was concluded that WU-K2R desulfurized NTH and BTH through the sulfur-specific degradation pathways with the selective cleavage of carbon-sulfur bonds. Therefore,
Rhodococcus
sp. strain WU-K2R, which could preferentially desulfurize asymmetric heterocyclic sulfur compounds such as NTH and BTH through the sulfur-specific degradation pathways, is a unique desulfurizing biocatalyst showing properties different from those of DBT-desulfurizing bacteria.
Differentially Regulated, Vegetative-Mycelium-Specific Hydrophobins of the Edible Basidiomycete
Pleurotus ostreatus
Authors: Peñas María M. , Rust Brian , Larraya Luis M. , Ramírez Lucía , Pisabarro Antonio G. 
Published: October 2002

ABSTRACT

Three different hydrophobins (Vmh1, Vmh2, and Vmh3) were isolated from monokaryotic and dikaryotic vegetative cultures of the edible fungus
Pleurotus ostreatus
. Their corresponding genes have a number of introns different from those of other
P. ostreatus
hydrophobins previously described. Two genes (
vmh1
and
vmh2
) were expressed only at the vegetative stage, whereas
vmh3
expression was also found in the fruit bodies. Furthermore, the expression of the three hydrophobins varied significantly with culture time and nutritional conditions. The three genes were mapped in the genomic linkage map of
P. ostreatus
, and evidence is presented for the allelic nature of
vmh2
and
POH3
and for the different locations of the genes coding for the glycosylated hydrophobins Vmh3 and POH2. The glycosylated nature of Vmh3 and its expression during vegetative growth and in fruit bodies suggest that it should play a role in development similar to that proposed for SC3 in
Schizophyllum commune
.
Isolation of
Shigella dysenteriae
Type 1 and
S. flexneri
Strains from Surface Waters in Bangladesh: Comparative Molecular Analysis of Environmental
Shigella
Isolates versus Clinical Strains
Authors: Faruque Shah M. , Khan Rasel , Kamruzzaman M. , Yamasaki Shinji , Ahmad Q. Shafi , Azim Tasnim , Nair G. Balakrish , Takeda Yoshifumi , Sack David A. 
Published: October 2002

ABSTRACT

Bacillary dysentery caused by
Shigella
species is a public health problem in developing countries including Bangladesh. Although, shigellae-contaminated food and drinks are often the source of the epidemic's spread, the possible presence of the pathogen and transmission of it through environmental waters have not been adequately examined. We analyzed surface waters collected in Dhaka, Bangladesh, for the presence of shigellae by a combination of PCR assays followed by concentration and culturing of PCR-positive samples. Analysis of 128 water samples by PCR assays for
Shigella
-specific virulence genes including
ipaBCD
,
ipaH
, and
stx1
identified 14 (10.9%) samples which were positive for one or more of these virulence genes. Concentration of the PCR-positive samples by filtration followed by culturing identified live
Shigella
species in 11 of the 14 PCR-positive samples. Analysis of rRNA gene restriction patterns (ribotype) showed that the environmental isolates shared ribotypes with a collection of clinical isolates, but in contrast to the clinical isolates, 10 of the 11 environmental isolates were either negative or carried deletions in the plasmid-encoded invasion-associated genes
ipaB
,
ipaC
, and
ipaD
. However, all environmental
Shigella
isolates were positive for the chromosomal multicopy invasion-associated gene
ipaH
and all
Shigella dysenteriae
type 1 isolates were positive for the
stx1
gene in addition to
ipaH
. This study demonstrated the presence of
Shigella
in the aquatic environment and dispersion of different virulence genes among these isolates which appear to constitute an environmental reservoir of
Shigella
-specific virulence genes. Since critical virulence genes in
Shigella
are carried by plasmids or mobile genetic elements, the environmental gene pool may contribute to an optimum combination of genes, causing the emergence of virulent
Shigella
strains which is facilitated in particular by close contact of the population with surface waters in Bangladesh.
Ability of Nonpathogenic
Fusarium oxysporum
Strain Fo47 To Induce Resistance against
Pythium ultimum
Infection in Cucumber
Authors: Benhamou Nicole , Garand Chantal , Goulet Alain 
Published: October 2002

ABSTRACT

The influence exerted by nonpathogenic
Fusarium oxysporum
strain Fo47 in triggering cucumber protection against infection by
Pythium ultimum
was investigated ultrastructurally. Macroscopic and microscopic observations of the pathogen colony in dual cultures revealed that reduction of
Pythium
growth was associated with marked disorders, including generalized disorganization of the host cytoplasm, retraction of the plasmalemma, and complete loss of the protoplasm. Cytochemical labeling of cellulose with an exoglucanase-gold complex showed that the cellulose component of the host cell walls was structurally preserved at a time when the host cytoplasm had undergone complete disorganization. A similar antagonistic process was observed at the root cell surface. Most striking and interesting was the finding that mycoparasitism, as evidenced by the frequent occurrence of Fo47 hyphae within nearly empty cells of the pathogen, occurred not only at the root surface but also within the invaded root tissues. The specific labeling pattern obtained with the exoglucanase-gold complex confirmed that Fo47 successfully penetrated cells of the pathogen, both in the rhizosphere and inside the root tissues.
Pythium
cells that could evade the first defensive line in the rhizosphere could penetrate the root epidermis, but their growth was restricted to the outermost tissues. Positive correlations between Fo47 treatment and induced resistance to infection by
P. ultimum
in cucumber were confirmed by (i) the reduction of pathogen viability; (ii) the elaboration of newly formed barriers, a phenomenon which was not seen in Fo47-free plants, where the pathogen proliferated in all root tissues within a few days; and (iii) the occlusion of intercellular spaces with a dense material likely enriched in phenolics. Taken together, our observations provide the first convincing evidence that Fo47 exerts a direct inhibitory effect on
P. ultimum
through a combination of antibiosis and mycoparasitism, in addition to being a strong inducer of plant defense reactions.
Internal Spatiotemporal Population Dynamics of Infection with ThreeWolbachiaStrains in the Adzuki Bean Beetle,Callosobruchus chinensis(Coleoptera: Bruchidae)
Authors: Ijichi Nobuyuki , Kondo Natsuko , Matsumoto Rena , Shimada Masakazu , Ishikawa Hajime , Fukatsu Takema 
Published: October 2002

ABSTRACTThe adzuki bean beetle,Callosobruchus chinensis, is infected with three distinct lineages of endosymbiotic bacteria belonging to the genusWolbachia, which were designated wBruCon, wBruOri, and wBruAus. In an attempt to understand the mechanisms underlying the infection with these three organisms, the spatiotemporal infection dynamics of the threeWolbachiastrains was investigated in detail by using a quantitative PCR technique. During the development ofC. chinensis, the wBruCon, wBruOri, and wBruAus infection levels consistently increased but the growth patterns were different. The levels of infection plateaued at the pupal stage at approximately 3 × 108, 2 × 108, and 5 × 107wspcopy equivalents per insect for wBruCon, wBruOri, and wBruAus, respectively. At the whole-insect level, the population densities of the threeWolbachiatypes did not show remarkable differences between adult males and females. At the tissue level, however, the total densities and relative levels of the threeWolbachiatypes varied significantly when different tissues and organs were compared and when the same tissues derived from males and females were compared. The histological data obtained by in situ hybridization and electron microscopy were concordant with the results of quantitative PCR analyses. Based on the histological data and the peculiarWolbachiacomposition commonly found in nurse tissues and oocytes, we suggest that theWolbachiastrains are vertically transmitted to oocytes not directly, but by way of nurse tissue. On the basis of our results, we discuss interactions among the three coinfectingWolbachiatypes, reproductive strategies ofWolbachia, and factors involved in the different cytoplasmic incompatibility phenotypes.
Extent of Variation of the
Bacillus thuringiensis
Toxin Reservoir: the Case of the Geranium Bronze,
Cacyreus marshalli
Butler (Lepidoptera: Lycaenidae)
Authors: Herrero Salvador , Borja Marisé , Ferré Juan 
Published: October 2002

ABSTRACT

Despite the fact that around 200
cry
genes from
Bacillus thuringiensis
have already been cloned, only a few Cry proteins are toxic towards a given pest. A crucial step in the mode of action of Cry proteins is binding to specific sites in the midgut of susceptible insects. Binding studies in insects that have developed cross-resistance discourage the combined use of Cry proteins sharing the same binding site. If resistance management strategies are to be implemented, the arsenal of Cry proteins suitable to control a given pest may be not so vast as it might seem at first. The present study evaluates the potential of
B. thuringiensis
for the control of a new pest, the geranium bronze (
Cacyreus marshalli
Butler), a butterfly that is threatening the popularity of geraniums in Spain. Eleven of the most common Cry proteins from the three lepidopteran-active Cry families (Cry1, Cry2, and Cry9) were tested against the geranium bronze for their toxicity and binding site relationships. Using
125
I-labeled Cry1A proteins we found that, of the seven most active Cry proteins, six competed for binding to the same site. For the long-term control of the geranium bronze with
B. thuringiensis
-based insecticides it would be advisable to combine any of the Cry proteins sharing the binding site (preferably Cry1Ab, since it is the most toxic) with those not competing for the same site. Cry1Ba would be the best choice of these proteins, since it is significantly more toxic than the others not binding to the common site.
Antimicrobial Resistance among Enterococci from Pigs in Three European Countries
Authors: Aarestrup Frank Møller , Hasman Henrik , Jensen Lars Bogø , Moreno Miguel , Herrero Inmaculada A. , Domínguez Lucas , Finn Maria , Franklin Anders 
Published: October 2002

ABSTRACT

Enterococci from pigs in Denmark, Spain, and Sweden were examined for susceptibility to antimicrobial agents and copper and the presence of selected resistance genes. The greatest levels of resistance were found among isolates from Spain and Denmark compared to those from Sweden, which corresponds to the amounts of antimicrobial agents used in food animal production in those countries. Similar genes were found to encode resistance in the different countries, but the
tet
(L) and
tet
(S) genes were more frequently found among isolates from Spain. A recently identified transferable copper resistance gene was found in all copper-resistant isolates from the different countries.