bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochemical Characterization of TEM-92 Extended-Spectrum β-Lactamase, a Protein Differing from TEM-52 in the Signal Peptide
Authors: Perilli Mariagrazia , Segatore Bernardetta , De Massis Maria Rosaria , Pagani Laura , Luzzaro Francesco , Rossolini Gian Maria , Amicosante Gianfranco 
Published: November 2002

ABSTRACT

A
bla
TEM-92
gene was cloned from a
Proteus mirabilis
isolate and expressed in
Escherichia coli
. Production of the enzyme caused reduction of susceptibility to penicillins and narrow- to expanded-spectrum cephalosporins but not to moxalactam and cephamycins. Determination of kinetic parameters with the purified enzyme revealed hydrolysis of expanded-spectrum cephalosporins, while cephamycins, moxalactam, and aztreonam were very poorly or not hydrolyzed. Clavulanate and penicillanic acid sulfones acylated TEM-92 slowly, and deacylation occurred at measurable rates.
AcrAB Efflux System: Expression and Contribution to Fluoroquinolone Resistance in
Klebsiella
spp
Authors: Mazzariol Annarita , Zuliani Jessica , Cornaglia Giuseppe , Rossolini Gian Maria , Fontana Roberta 
Published: November 2002

ABSTRACT

Seven
Klebsiella pneumoniae
and four
Klebsiella oxytoca
clinical isolates with different levels of resistance to ciprofloxacin were studied. Mutations in the topoisomerase genes were found in almost all strains, but the contribution of a multidrug efflux system homologous to AcrAB in
Escherichia coli
was also observed. Overexpression of this efflux system was demonstrated by immunoblotting with antibodies against
E. coli
AcrA.
Erythromycin-Resistant Pharyngeal Isolates of
Streptococcus pyogenes
Recovered in Italy
Authors: Dicuonzo Giordano , Fiscarelli Ersilia , Gherardi Giovanni , Lorino Giulia , Battistoni Fabrizio , Landi Simona , De Cesaris Marina , Petitti Tommasangelo , Beall Bernard 
Published: November 2002

ABSTRACT

Three classes of macrolide resistance phenotypes and three different erythromycin resistance determinants were found among 127 erythromycin-resistant group A streptococcal (GAS) isolates recovered from 355 (35.8%) pediatric pharyngitis patients in Rome, Italy. According to
emm
and
sof
sequence typing results, erythromycin-resistant isolates comprised 11 different clonal types. Remarkably, 126 of the 127 macrolide-resistant isolates were serum opacity factor (
sof
) gene positive. These data suggest a strong association between macrolide resistance and the presence of
sof
among GAS isolates recovered from Italian pediatric pharyngitis patients.
Prevalence of Clinical Isolates of
Escherichia coli
Producing Inhibitor-Resistant β-Lactamases at a University Hospital in Barcelona, Spain, over a 3-Year Period
Authors: Miró Elisenda , Navarro Ferran , Mirelis Beatriz , Sabaté Montserrat , Rivera Alba , Coll Pere , Prats Guillem 
Published: November 2002

ABSTRACT

About 7% of 7,252 nonduplicated clinical
Escherichia coli
strains from a Spanish hospital showed reduced susceptibility to amoxicillin-clavulanate. Of these, 0.37% produced the IRTs TEM-30, TEM-31, TEM-33, TEM-34, TEM-37, TEM-40, TEM-51, and TEM-54; 5.3% were probable class C β-lactamase overproducers; 0.8% were probable TEM-1 hyperproducers; 0.18% produced OXA-30; 0.15% overexpressed SHV-1; and 0.03% produced a PSE-1 enzyme.
In Vitro Activities of Garenoxacin (BMS 284756) against 108 Clinical Isolates of
Gardnerella vaginalis
Authors: Goldstein Ellie J. C. , Citron Diane M. , Merriam C. Vreni , Warren Yumi A. , Tyrrell Kerin L. , Fernandez Helen T. 
Published: November 2002

ABSTRACT

Garenoxacin (BMS 284756) was active against 105 of 108 (97%) recent clinical
Gardnerella vaginalis
isolates at ≤2 μg/ml by using the reference agar dilution method for anaerobes. Twenty-eight percent of isolates (31 of 108) were resistant to metronidazole, and 44% were resistant to doxycycline. All were susceptible to clindamycin and ampicillin-sulbactam.
In Vitro Killing Effect of Moxifloxacin on Clinical Isolates of
Stenotrophomonas maltophilia
Resistant to Trimethoprim-Sulfamethoxazole
Authors: Giamarellos-Bourboulis Evangelos J. , Karnesis Lazaros , Galani Irene , Giamarellou Helen 
Published: November 2002

ABSTRACT

The time-kill effect of moxifloxacin on 20 genetically distinct isolates of
Stenotrophomonas maltophilia
resistant to trimethoprim-sulfamethoxazole was studied. The majority (80%) were killed by a concentration equivalent to four times the MIC; the MIC induced a transient decrease in bacterial counts at 4 h, followed by regrowth. No effect was detected in four isolates. These results merit further clinical consideration.
Phenotypic and Genotypic Analysis of Biologically Cloned Human Immunodeficiency Virus Type 1 Isolates from Patients Treated with Zidovudine and Lamivudine
Authors: Stoeckli Thomas C. , MaWhinney Samantha , Uy Jonathan , Duan Chengying , Lu Jing , Shugarts David , Kuritzkes Daniel R. 
Published: November 2002

ABSTRACT
Mutations at reverse transcriptase codons 44, 118, 207, and 208 were significantly correlated with reduced zidovudine susceptibility in biologically cloned human immunodeficiency virus type 1 (HIV-1) isolates. Sequences from the Stanford HIV RT and Protease Sequence Database showed that these mutations were more common in HIV-1 isolates from patients treated with zidovudine and lamivudine than in patients not treated with these drugs.
Structure-Activity Relationship of a New Class of Anti-Hepatitis B Virus Agents
Authors: Mehta Anand , Conyers Bertha , Tyrrell D. L. J. , Walters Kathie-Anne , Tipples Graham A. , Dwek Raymond A. , Block Timothy M. 
Published: November 2002

ABSTRACT

N
-Nonyl-deoxy-galactonojirimycin (
N
-nonyl-DGJ) has been shown to reduce the amount of hepatitis B virus (HBV) produced by tissue cultures under conditions where cell viability is not affected. We show here that the compound
N
-nonyl-DGJ was effective against lamivudine-resistant HBV mutants bearing the YMDD motif in the polymerase gene, consistent with the compound's activity being distinct from those of nucleoside inhibitors. To better understand the chemical structures that influence its antiviral activity, a series of imino sugar derivatives were made and tested for their antiviral activity against HBV. This work suggests that the antiviral activity of the alkovirs requires an alkyl chain length of at least eight carbons but that the galactose-based head group can be modified with little or no loss in activity.
High Concentrations of Nelfinavir as an Independent Risk Factor for Lipodystrophy in Human Immunodeficiency Virus-Infected Patients
Authors: Tréluyer Jean-Marc , Morini Jean-Pierre , Dimet Jérome , Gorin Isabelle , Rey Elisabeth , Deleuze Jean , Ceccaldi Pierre-François , Escande Jean-Paul , Pons Gérard , Dupin Nicolas 
Published: November 2002

ABSTRACT
To assess the relationship between antiretroviral drug exposure and lipodystrophy, 69 human immunodeficiency virus type 1-infected patients receiving nelfinavir were investigated cross-sectionally. Lipodystrophy was defined by patients' self-report. Nelfinavir trough concentrations in plasma were significantly related to overall lipodystrophy and peripheral fat wasting scores and appeared to be an independent risk factor for lipodystrophy
Uptake and Intracellular Activity of Linezolid in Human Phagocytes and Nonphagocytic Cells
Authors: Pascual Álvaro , Ballesta Sofía , García Isabel , Perea Evelio J. 
Published: November 2002

ABSTRACTThe intracellular penetration and activity of linezolid in human polymorphonuclear leukocytes and tissue-cultured cells (McCoy) were evaluated. Linezolid reached intracellular concentrations slightly greater than extracellular ones in both types of cell. The uptake was rapid and not saturable and was affected by environmental temperature and cell viability. Linezolid showed slight intracellular activity againstStaphylococcus epidermidisat high extracellular concentrations.
New Automated Method for Determining Postantifungal Effect of Amphotericin B againstCandidaSpecies: Effects of Concentration, Exposure Time, and Area under the Curve
Authors: Chryssanthou Erja , Cars Otto , Sjölin Jan 
Published: November 2002

ABSTRACTThe postantifungal effect (PAFE) of amphotericin B was determined with a BacT/Alert automated system, which is based on the colorimetric detection of CO2. The levels of accuracy and precision of the automated method were high. Longer PAFEs were obtained forCandidaalbicans(P< 0.001),C. glabrata(P< 0.01), andC. krusei(P< 0.01) at increasing amphotericin B concentrations and exposure times.
In Vitro Activity of Moxifloxacin against Bacteria Isolated from Odontogenic Abscesses
Authors: Sobottka Ingo , Cachovan Georg , Stürenburg Enno , Ahlers M. Oliver , Laufs Rainer , Platzer Ursula , Mack Dietrich 
Published: November 2002

ABSTRACT

We evaluated the antimicrobial susceptibility of 87 pathogens isolated from 37 patients with odontogenic abscesses. The most prevalent bacteria were viridans group streptococci and
Prevotella
species. Considering all bacterial isolates, 100% were susceptible to amoxicillin-clavulanic acid, 98% were susceptible to moxifloxacin and to levofloxacin, 76% were susceptible to doxycycline, 75% were susceptible to clindamycin, and 69% were susceptible to penicillin.
Postantibiotic Effect and Delay of Regrowth in Strains Carrying Mutations That Save Proteins or RNA
Authors: Dolcino Marzia , Zoratti Alberto , Debbia Eugenio A. , Schito Gian Carlo , Marchese Anna 
Published: November 2002

ABSTRACT

The postantibiotic effect (PAE) values found for proteinase-defective (Lon
−
)
Escherichia coli
and RNase-defective
E. coli
exposed to antibiotics were reduced (31 to 60% and 35 to 50%, respectively) in comparison with the control (AB1157), and in the
recA13
mutant these values were about 0.4 h with all drugs. Nalidixic acid, under anaerobic conditions, induced no PAE (0 to 0.1 h) in AB1157. A delay in regrowth (0.2 to 0.26 h) was noted with
dnaA46
(Ts),
gyrA43
(Ts), and
gyrB41
(Ts) mutants cultured for 2 h at 43°C. These findings suggest that when proteins and RNA are saved, the cell rapidly resumes the original growth rate.
Novel Variant (
bla
VIM-4
) of the Metallo-β-Lactamase Gene
bla
VIM-1
in a Clinical Strain of
Pseudomonas aeruginosa
Authors: Pournaras Spyros , Tsakris Athanassios , Maniati Maria , Tzouvelekis Leonidas S. , Maniatis Antonios N. 
Published: November 2002

ABSTRACT

A
Pseudomonas aeruginosa
isolate highly resistant to carbapenems was collected from a patient with postsurgical cerebrospinal infection in Greece. The isolate carried a class 1 integron that contained as a sole cassette the gene
bla
VIM-4
, a novel variant of
bla
VIM-1
, with one nucleotide difference resulting in a Ser-to-Arg change at amino acid position 175 of the VIM-1 enzyme. This is the first detection of a VIM-1 variant after its appearance in Italy.
Pharmacodynamic Modeling of Clarithromycin against Macrolide-Resistant [PCR-Positive
mef
(A) or
erm
(B)]
Streptococcus pneumoniae
Simulating Clinically Achievable Serum and Epithelial Lining Fluid Free-Drug Concentrations
Authors: Noreddin Ayman M. , Roberts Danielle , Nichol Kim , Wierzbowski Aleksandra , Hoban Daryl J. , Zhanel George G. 
Published: November 2002

ABSTRACT

The association between macrolide resistance mechanisms and clinical outcomes remains understudied. The present study, using an in vitro pharmacodynamic model, assessed clarithromycin (CLR) activity against
mef
(A)-positive and
erm
(B)-negative
Streptococcus pneumoniae
isolates by simulating free-drug concentrations in serum and both total (protein-bound and free) and free drug in epithelial lining fluid (ELF). Five
mef
(A)-positive and
erm
(B)-negative strains, one
mef
(A)-negative and
erm
(B)-positive strain, and a control [
mef
(A)-negative and
erm
(B)-negative] strain of
S. pneumoniae
were tested. CLR was modeled using a one-compartment model, simulating a dosage of 500 mg, per os, twice a day (in serum, free-drug

C
p

maximum of 2 μg/ml,
t
1/2
of 6 h; in ELF,
C
ELF(total)
maximum of 35μg/ml,
t
1/2
of 6 h; C
ELF(free)
maximum of 14 μg/ml,
t
1/2
of 6 h). Starting inocula were 10
6
CFU/ml in Mueller-Hinton broth with 2% lysed horse blood. With sampling at 0, 4, 8, 12, 20, and 24 h, the extent of bacterial killing was assessed. Achieving CLR T/MIC values of ≥90% (AUC
0-24
/MIC ratio, ≥61) resulted in bacterial eradication, while T>MIC values of 40 to 56% (AUC
0-24
/MIC ratios of ≥30.5 to 38) resulted in a 1.2 to 2.0 log
10
CFU/ml decrease at 24 h compared to that for the initial inoculum. CLR T/MIC values of ≤8% (AUC
0-24
/MIC ratio, ≤17.3) resulted in a static effect or bacterial regrowth. The high drug concentrations in ELF that were obtained clinically with CLR may explain the lack of clinical failures with
mef
(A)-producing
S. pneumoniae
strains, with MICs up to 8 μg/ml. However,
mef
(A) isolates for which MICs are ≥16 μg/ml along with
erm
(B) may result in bacteriological failures.
Promoters
P3
,
Pa
/
Pb
,
P4
, and
P5
Upstream from
bla
TEM
Genes and Their Relationship to β-Lactam Resistance
Authors: Lartigue Marie Frédérique , Leflon-Guibout Véronique , Poirel Laurent , Nordmann Patrice , Nicolas-Chanoine Marie-Hélène 
Published: November 2002

ABSTRACT

Using an isogenic system, we have determined the impact that the four promoters known to control
bla
TEM
gene expression have on β-lactamase activity. For both TEM-1 and TEM-30, this activity gradually increased in relation to the presence of promoters
P3
,
Pa/Pb
, and
P4
upstream of the corresponding gene. Promoter
P5
, only found upstream of the
bla
TEM-1B
gene, was related to the highest expression of this gene.
Chromosome-Encoded Ambler Class A β-Lactamase of
Kluyvera georgiana
, a Probable Progenitor of a Subgroup of CTX-M Extended-Spectrum β-Lactamases
Authors: Poirel Laurent , Kämpfer Peter , Nordmann Patrice 
Published: November 2002

ABSTRACT

A chromosome-encoded β-lactamase gene, cloned and expressed in
Escherichia coli
from
Kluyvera georgiana
reference strain CUETM 4246-74 (DSM 9408), encoded the extended-spectrum β-lactamase KLUG-1, which shared 99% amino acid identity with the plasmid-mediated β-lactamase CTX-M-8. This work provides further evidence that
Kluyvera
spp. may be the progenitor(s) of CTX-M-type β-lactamases.
Antimicrobial Peptides from Human Platelets
Authors: Tang Yi-Quan , Yeaman Michael R. , Selsted Michael E. 
Published: November 2002

ABSTRACTPlatelets share structural and functional similarities with granulocytes known to participate in antimicrobial host defense. To evaluate the potential antimicrobial activities of platelet proteins, normal human platelets were stimulated with human thrombin in vitro. Components of the stimulated-platelet supernatants were purified to homogeneity by reversed-phase high-performance liquid chromatography. Purified peptides with inhibitory activity againstEscherichia coliML35 in an agar diffusion antimicrobial assay were characterized by mass spectrometry, amino acid analysis, and sequence determination. These analyses enabled the identification of seven thrombin-releasable antimicrobial peptides from human platelets: platelet factor 4 (PF-4), RANTES, connective tissue activating peptide 3 (CTAP-3), platelet basic protein, thymosin β-4 (Tβ-4), fibrinopeptide B (FP-B), and fibrinopeptide A (FP-A). With the exception of FP-A and FP-B, all peptides were also purified from acid extracts of nonstimulated platelets. The in vitro antimicrobial activities of the seven released peptides were further tested against bacteria (E. coliandStaphylococcus aureus) and fungi (Candida albicansandCryptococcus neoformans). Each peptide exerted activity against at least two organisms. Generally, the peptides were more potent against bacteria than fungi, activity was greater at acidic pHs, and antimicrobial activities were dose dependent. Exceptions to these observations were observed with PF-4, which displayed a bimodal dose-response relationship in microbicidal assays, and Tβ-4, which had greater activity at alkaline pHs. At concentrations at which they were individually sublethal, PF-4 and CTAP-3 exerted synergistic microbicidal activity againstE. coli. Collectively, these findings suggest a direct antimicrobial role for platelets as they are activated to release peptides in response to trauma or mediators of inflammation.
Construction of a Novel Transposon Mutagenesis System Useful in the Isolation of
Streptococcus parasanguis
Mutants Defective in Fap1 Glycosylation
Authors: Chen Qiang , Wu Hui , Fives-Taylor Paula M. 
Published: November 2002

ABSTRACT

Streptococcus parasanguis
, a primary colonizer of the tooth surface, has long, peritrichous fimbriae. A fimbria-associated protein, Fap1, is identified as an adhesin of
S. parasanguis
FW213. The mature Fap1 protein is glycosylated, and the glycosylation is required for fimbria biogenesis and bacterial adhesion. Little is known about the mechanism of Fap1 glycosylation due to the lack of identifiable mutants. A novel transposon mutagenesis system was established and used to generate a mutant library. Screening of the library with a monoclonal antibody specific for a glycan epitope of Fap1 yielded six mutants with decreased expression levels of surface-associated glycosylated Fap1 protein. Southern blot analyses revealed that three of the mutants had the transposon inserted in the
fap1
locus, whereas the other three mutants had insertions in other genes. Among the latter three mutants, two expressed Fap1 polypeptides on which no glycosylation was detected by glycan-specific antibodies; the other mutant expressed a partially glycosylated Fap1 polypeptide. These data suggest that three mutants were isolated with defects in genes implicated in Fap1 glycosylation.
Induction of Keratinocyte Growth Factor 1 Expression by Lipopolysaccharide Is Regulated by CD-14 and Toll-Like Receptors 2 and 4
Authors: Putnins Edward E. , Sanaie Ali-Reza , Wu Qiang , Firth James D. 
Published: November 2002

ABSTRACTPeriodontal disease is a chronic inflammatory condition that is associated with increased concentrations of gram-negative pathogenic bacteria and epithelial cell proliferation. Regulation of this proliferation is poorly understood but is most likely controlled by locally expressed growth factors. Keratinocyte growth factor 1, an epithelium-specific growth factor, is expressed by gingival fibroblasts, and its expression is regulated in a concentration-dependent manner by lipopolysaccharide. In this study, induction of keratinocyte growth factor 1 protein expression was dependent on gingival fibroblast expression of membrane CD14 (mCD14) and Toll-like receptors 2 and 4. Lipopolysaccharides fromEscherichia coliandPorphyromonas gingivalisinduced membrane expression of CD14 at 1, 3, and 24 h. Specifically, lipopolysaccharide induced low mCD14 expression gingival fibroblasts to express mCD14 at a level consistent with that of high mCD14 expression cells. Functional studies with specific blocking antibodies for CD14 and Toll-like receptors 2 and 4 implicated all of these molecules in signal transduction. The rapid decrease in cell membrane expression of Toll-like receptors 2 and 4 after treatment with lipopolysaccharide was consistent with receptor internalization, and blocking of either of these receptors completely inhibited keratinocyte growth factor 1 protein expression. The transcription factors AP-1 and NF-κB were involved in lipopolysaccharide induction of keratinocyte growth factor 1 mRNA and protein expression. These results suggest that lipopolysaccharide may induce proliferation of periodontal epithelial cells by upregulating keratinocyte growth factor 1 expression via the CD14 and Toll-like receptor signaling pathway.
Mycobacterium bovisBCG Producing Interleukin-18 Increases Antigen-Specific Gamma Interferon Production in Mice
Authors: Biet Franck , Kremer Laurent , Wolowczuk Isabelle , Delacre Myriam , Locht Camille 
Published: November 2002

ABSTRACTInterleukin-18 (IL-18) and IL-12 play a critical role in the expression of cell-mediated immunity involved in host defense against intracellular pathogens. Both cytokines are produced by macrophages and act in synergy to induce gamma interferon (IFN-γ) production by T, B, and natural killer cells. In the present study, we analyzed both cellular and humoral responses upon infection with IL-18-secreting BCG of BALB/c and C3H/HeJ mice, two strains known to differ in their ability to support the growth of BCG. The cDNA encoding mature IL-18 was fused in frame with the alpha-antigen signal peptide-coding sequence, cloned downstream of the mycobacterialhsp60promoter and expressed in BCG. IL-18 produced by the recombinant BCG strain was functional, as judged by NF-κB-mediated luciferase induction in a tissue culture assay. When susceptible mice were infected with IL-18-producing BCG, their splenocytes were found to produce higher amounts of Th1 cytokines after stimulation with mycobacterial antigens than the splenocytes of mice infected with the nonrecombinant BCG. This was most prominent for IFN-γ, although the mycobacterial antigen-specific secretion of granulocyte-macrophage colony-stimulating factor and IL-10 was also augmented after infection with the recombinant BCG compared to infection with nonrecombinant BCG. In contrast, the immunoglobulin G levels in serum against mycobacterial antigens were lower when the mice were infected with IL-18-producing BCG compared to infection with nonrecombinant BCG. The IL-18 effect was delayed in BALB/c compared to C3H/HeJ mice. These results indicate that the production of IL-18 by recombinant BCG may enhance the immunomodulatory properties of BCG further toward a Th1 profile. This may be particularly useful for immunotherapeutic or prophylactic interventions in which a Th1 response is most desirable.
Effect ofMycobacterium tuberculosis-Specific 10-Kilodalton Antigen on Macrophage Release of Tumor Necrosis Factor Alpha and Nitric Oxide
Authors: Trajkovic Vladimir , Singh Gyanesh , Singh Balwan , Singh Sarman , Sharma Pawan 
Published: November 2002

ABSTRACTSecreted proteins ofMycobacterium tuberculosisare major targets of the specific immunity in tuberculosis and constitute promising candidates for the development of more efficient vaccines and diagnostic tests. We show here thatM. tuberculosis-specific antigen 10 (MTSA-10, originally designated CFP-10) can bind to the surface of mouse J774 macrophage-like cells and stimulate the secretion of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). MTSA-10 also synergized with gamma interferon (IFN-γ) for the induction of the microbicidal free radical nitric oxide (NO) in J774 cells, as well as in bone marrow-derived and peritoneal macrophages. On the other hand, pretreatment of J774 cells with MTSA-10 markedly reduced NO but not TNF-α or interleukin 10 (IL-10) release upon subsequent stimulation with lipopolysaccharide or the cell lysate ofM. tuberculosis. The presence of IFN-γ during stimulation withM. tuberculosislysate antagonized the desensitizing effect of MTSA-10 pretreatment on macrophage NO production. The activation of protein tyrosine kinases (PTK) and the serine/threonine kinases p38 MAPK and ERK was apparently required for MTSA-10 induction of TNF-α and NO release, as revealed by specific kinase inhibitors. However, only p38 MAPK activity, not PTK or ERK activity, was partly responsible for MTSA-10-mediated macrophage desensitization. The modulation of macrophage function by MTSA-10 suggests a novel mechanism for its involvement in immunopathogenesis of tuberculosis and might have implications for the prevention, diagnosis, and therapy of this disease.