bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular Characterization of FOX-4, a New AmpC-Type Plasmid-Mediated β-Lactamase from an
Escherichia coli
Strain Isolated in Spain
Authors: Bou Germán , Oliver Antonio , Ojeda Mar , Monzón Carmelo , Martínez-Beltrán Jesús 
Published: July 2002

ABSTRACT

A clinical strain of
Escherichia coli
(Ec GCE) displayed resistance to cefoxitin, cefotetan, cefotaxime, and ceftazidime. Susceptibility was not restored by the addition of clavulanic acid. Two β-lactamases with apparent pIs of 5.4 and 6.4 were identified; the β-lactamase with a pI of 6.4 was transferred by conjugation and associated with a 40-kb plasmid. Analysis of the nucleotide sequence showed a new
ampC
β-lactamase gene that is closely related to those encoding the FOX-3, FOX-2, and FOX-1 β-lactamases but whose product has four novel amino acid mutations, at positions 11 (M→T), 43 (A→E), 233 (V→A), and 280 (Y→H). This first cephamycinase from Spain was named FOX-4.
Fluconazole Penetration into the Pancreas
Authors: Shrikhande Shailesh , Friess Helmut , Issenegger Claudia , Martignoni Marcus E. , Yong Huang , Gloor Beat , Yeates Rodney , Kleeff Jörg , Büchler Markus W. 
Published: July 2002

ABSTRACT
Because of antibiotic prophylaxis for necrotizing pancreatitis, the frequency of fungal superinfection in patients with pancreatic necrosis is increasing. In this study we analyzed the penetration of fluconazole into the human pancreas and in experimental acute pancreatitis. In human pancreatic tissues, the mean fluconazole concentration was 8.19 ± 3.38 μg/g (96% of the corresponding concentration in serum). In experimental edematous and necrotizing pancreatitis, 88 and 91% of the serum fluconazole concentration was found in the pancreas. These data show that fluconazole penetration into the pancreas is sufficient to prevent and/or treat fungal contamination in patients with pancreatic necrosis.
Enhancement of Fluoroquinolone Activity by C-8 Halogen and Methoxy Moieties: Action against a Gyrase Resistance Mutant of
Mycobacterium smegmatis
and a Gyrase-Topoisomerase IV Double Mutant of
Staphylococcus aureus
Authors: Lu Tao , Zhao Xilin , Li Xinying , Drlica-Wagner Alex , Wang Jian-Ying , Domagala John , Drlica Karl 
Published: July 2002

ABSTRACT

The increasing prevalence of antibiotic resistance among bacterial pathogens prompted a microbiological study of fluoroquinolone structure-activity relationships with resistant mutants. Bacteriostatic and bactericidal activities for 12 fluoroquinolones were examined with a gyrase mutant of
Mycobacterium smegmatis
and a gyrase-topoisomerase IV double mutant of
Staphylococcus aureus
. For both organisms C-8 halogen and C-8 methoxy groups enhanced activity. The MIC at which 99% of the isolates tested were inhibited (MIC
99
) was reduced three- to fivefold for the
M. smegmatis
mutant and seven- to eightfold for the
S. aureus
mutant by C-8 bromine, chlorine, and methoxy groups. With both organisms a smaller reduction in the MIC
99
(two- to threefold) was associated with a C-8 fluorine moiety. In most comparisons with
M. smegmatis
the response to a C-8 substituent was similar (within twofold) for wild-type and mutant cells. In contrast, mutant
S. aureus
was affected more than the wild type by the addition of a C-8 substituent. C-8 halogen and methoxy groups also improved the ability to kill the two mutants and the respective wild-type cells when measured with various fluoroquinolone concentrations during an incubation period equivalent to four to five doubling times. Collectively these data help define a group of fluoroquinolones that can serve (i) as a base for structure refinement and (ii) as test compounds for slowing the development of fluoroquinolone resistance during infection of vertebrate hosts.
Acyclovir for Treatment of Postherpetic Neuralgia: Efficacy and Pharmacokinetics
Authors: Acosta Edward P. , Balfour Henry H. 
Published: July 2002

ABSTRACT
Postherpetic neuralgia is the most common complication of herpes zoster (shingles) in the immunocompetent host. Its mechanism is incompletely understood, but one postulate is that continuous replication of varicella-zoster virus (VZV) in nerve tissues may be responsible for the pain. If this is so, antiviral treatment could be advantageous. To test this hypothesis, we performed a randomized, double-blind, placebo-controlled trial of intravenous acyclovir (10 mg/kg every 8 h [q8h]) for 14 days, followed by oral acyclovir (800 mg q6h) for 42 days in 10 subjects (median age, 71 years) who had experienced at least 6 months of severe pain (median duration of postherpetic neuralgia before enrollment, 3.2 years). Intensive and sparse pharmacokinetic sampling occurred during both dosing phases of the study. One- and two-compartment models were fitted to the oral and intravenous concentration-time data, respectively. The four men and four women assigned to acyclovir during either or both dosing phases tolerated it well. Pharmacokinetic results were similar to those previously reported in younger individuals. The mean oral clearance and elimination half-life following oral dosing were 1.47 liters/h/kg and 2.78 h, respectively. Total clearance and terminal half-life following intravenous administration were 0.16 liters/h/kg and 3.67 h, respectively. Only 1 of 10 participants reported definite improvement in the severity of postherpetic pain, and treatment had no effect on titers of humoral antibody to VZV. We concluded that 56 days of intravenous and oral acyclovir therapy were well tolerated but had little or no effect on the clinical course of postherpetic neuralgia.
Single Ribosomal Protein Mutations in Antibiotic-Resistant Bacteria Analyzed by Mass Spectrometry
Authors: Wilcox Sheri K. , Cavey Gregory S. , Pearson James D. 
Published: July 2002

ABSTRACT

Mutations in several ribosomal proteins are known to be related to antibiotic resistance. For several strains of
Escherichia coli
, the mutated protein is known but the amino acid actually altered has not been documented. Characterization of these determinants for antibiotic resistance in proteins will further the understanding of the precise mechanism of the antibiotic action as well as provide markers for resistance. Mass spectrometry can be used as a valuable tool to rapidly locate and characterize mutant proteins by using a small amount of material. We have used electrospray and matrix-assisted laser desorption ionization–time of flight (MALDI–TOF) mass spectrometry to map out all 56 ribosomal proteins in
E. coli
based on intact molecular masses. We used this fingerprinting approach to locate variants of ribosomal proteins displaying a change in mass. In particular we have studied proteins responsible for streptomycin, erythromycin, and spectinomycin resistance in three strains of
E. coli
, and then we characterized each mutation responsible for resistance by analyzing tryptic peptides of these proteins by using MALDI-TOF and nanoelectrospray tandem mass spectrometry. The results provided markers for antibiotic resistance and demonstrated that mass spectrometry can be used to rapidly investigate changes in individual proteins from a complex with picomole amounts of protein.
Pharmacodynamics and Bactericidal Activity of Moxifloxacin in Experimental
Escherichia coli
Meningitis
Authors: Rodriguez-Cerrato Violeta , McCoig Cynthia C. , Michelow Ian C. , Ghaffar Faryal , Jafri Hasan S. , Hardy Robert D. , Patel Chetan , Olsen Kurt , McCracken George H. 
Published: July 2002

ABSTRACT

Moxifloxacin, an 8-methoxyquinolone with broad-spectrum activity in vitro, was studied in the rabbit model of
Escherichia coli
meningitis. The purposes of this study were to evaluate the bactericidal effectiveness and the pharmacodynamic profile of moxifloxacin in cerebrospinal fluid (CSF) and to compare the bactericidal activity with that of ceftriaxone and meropenem therapy. After induction of meningitis, animals were given single doses of 10, 20, and 40 mg/kg or divided-dose regimens of 5, 10, and 20 mg/kg twice, separated by 6 h. After single doses, the penetration of moxifloxacin into purulent CSF, measured as percentage of the area under the concentration-time curve (AUC) in CSF relative to the AUC in plasma, was approximately 50%. After single doses of 10, 20, and 40 mg/kg, the maximum CSF concentration (
C
max
) values were 1.8, 4.2, and 4.9 μg/ml, respectively; the AUC values (total drug) were 13.4, 25.4, and 27.1 μg/ml · h, respectively, and the half-life values (
t
½
) were 6.7, 6.6, and 4.7 h, respectively. The bacterial killing in CSF for moxifloxacin, calculated as the Δlog
10
CFU per milliliter per hour, at 3, 6, and 12 h after single doses of 10, 20, and 40 mg/kg were −5.70, −6.62, and −7.02; −7.37, −7.37, and −6.87; and −6.62, −6.62, and −6.62, respectively, whereas those of ceftriaxone and meropenem were −4.18, −5.24, and −4.43, and −3.64, −3.59, and −4.12, respectively. The CSF pharmacodynamic indices of AUC/MBC and
C
max
/MBC were interrelated (
r
= 0.81); there was less correlation with
T
> MBC (
r
= 0.74). In this model, therapy with moxifloxacin appears to be at least as effective as ceftriaxone and more effective than meropenem therapy in eradicating
E. coli
from CSF.
Experimental and Conformational Analyses of Interactions between Butenafine and Lipids
Authors: Mingeot-Leclercq Marie-Paule , Gallet Xavier , Flore Christel , Van Bambeke Françoise , Peuvot Jacques , Brasseur Robert 
Published: July 2002

ABSTRACT

Butenafine (
N
-4-
tert
-butylbenzyl-
N
-methyl-1-naphtalenemethylamine hydrochloride) is an antifungal agent of the benzylamine class that has excellent therapeutic efficacy and a remarkably long duration of action when applied topically to treat various mycoses. Given the lipophilic nature of the molecule, efficacy may be related to an interaction with cell membrane phospholipids and permeabilization of the fungal cell wall. Similarly, high lipophilicity could account for the long duration of action, since fixation to lipids in cutaneous tissues might allow them to act as local depots for slow release of the drug. We have therefore used computer-assisted conformational analysis to investigate the interaction of butenafine with lipids and extended these observations with experimental studies in vitro using liposomes. Conformational analysis of mixed monolayers of phospholipids with the neutral and protonated forms of butenafine highlighted a possible interaction with both the hydrophilic and hydrophobic domains of membrane phospholipids. Studies using liposomes demonstrated that butenafine increases membrane fluidity [assessed by fluorescence polarization of 1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene and 1,6-diphenylhexatriene] and membrane permeability (studied by release of calcein from liposomes). The results show, therefore, that butenafine readily interacts with lipids and is incorporated into membrane phospholipids. These findings may help explain the excellent antifungal efficacy and long duration of action of this drug when it is used as a topical antifungal agent in humans.
MDR1
-Mediated Drug Resistance in
Candida dubliniensis
Authors: Wirsching Stephanie , Moran Gary P. , Sullivan Derek J. , Coleman David C. , Morschhäuser Joachim 
Published: July 2002

ABSTRACT

Candida dubliniensis
is a recently described opportunistic fungal pathogen that is closely related to
Candida albicans. Candida dubliniensis
readily develops resistance to the azole antifungal agent fluconazole, both in vitro and in infected patients, and this resistance is usually associated with upregulation of the
CdMDR1
gene, encoding a multidrug efflux pump of the major facilitator superfamily. To determine the role of
CdMDR1
in drug resistance in
C. dubliniensis
, we constructed an
mdr1
null mutant from the fluconazole-resistant clinical isolate CM2, which overexpressed the
CdMDR1
gene. Sequential deletion of both
CdMDR1
alleles was performed by the
MPA
R
-flipping method, which is based on the repeated use of a dominant mycophenolic acid resistance marker for selection of integrative transformants and its subsequent deletion from the genome by FLP-mediated, site-specific recombination. In comparison with its parental strain, the
mdr1
mutant showed decreased resistance to fluconazole but not to the related drug ketoconazole. In addition, we found that
CdMDR1
confers resistance to the structurally unrelated drugs 4-nitroquinoline-
N
-oxide, cerulenin, and brefeldin A, since the enhanced resistance to these compounds of the parent strain CM2 compared with the matched susceptible isolate CM1 was abolished in the
mdr1
mutant. In contrast,
CdMDR1
inactivation did not cause increased susceptibility to amorolfine, terbinafine, fluphenazine, and benomyl, although overexpression of
CdMDR1
in a hypersusceptible
Saccharomyces cerevisiae
strain had previously been shown to confer resistance to these compounds. The effect of
CdMDR1
inactivation was identical to that seen in two similarly constructed
C. albicans mdr1
mutants. Therefore, despite species-specific differences in the amino acid sequences of the Mdr1 proteins, overexpression of
CaMDR1
and
CdMDR1
in clinical
C. albicans
and
C. dubliniensis
strains seems to confer the same drug resistance profile in both species.
Enterocin P Causes Potassium Ion Efflux from
Enterococcus faecium
T136 Cells
Authors: Herranz Carmen , Cintas Luis M. , Hernández Pablo E. , Moll Gert N. , Driessen Arnold J. M. 
Published: July 2002

ABSTRACT

Enterocin P is a bacteriocin produced by
Enterococcus faecium
P13. We studied the mechanism of its bactericidal action using enterocin-P-sensitive
E. faecium
T136 cells. The bacteriocin is incapable of dissipating the transmembrane pH gradient. On the other hand, depending on the buffer used, enterocin P dissipates the transmembrane potential. Enterocin P efficiently elicits efflux of potassium ions, but not of intracellularly accumulated anions like phosphate and glutamate. Taken together, these data demonstrate that enterocin P forms specific, potassium ion-conducting pores in the cytoplasmic membrane of target cells.
Rapid Screening Technique for Class 1 Integrons in
Enterobacteriaceae
and Nonfermenting Gram-Negative Bacteria and Its Use in Molecular Epidemiology
Authors: Maguire Alison J. , Brown Derek F. J. , Gray James J. , Desselberger Ulrich 
Published: July 2002

ABSTRACT

A screening technique for integrons in members of the family
Enterobacteriaceae
and nonfermenting gram-negative bacteria by real-time PCR is reported. A total of 226 isolates of gram-negative bacteria obtained from a variety of clinical specimens were screened for class 1 integrons by real-time PCR performed on a LightCycler instrument. This technique used a primer pair specific for a 300-bp conserved region at the 5′ ends of class 1 integrons. The screening assay was evaluated by comparison with results obtained by the conventional, thermal-block PCR (long PCR) by using established conditions and primers for the detection of class 1 integrons, and the real-time PCR technique was thus shown to be both sensitive and specific. DNA from 50 of 226 (22%) isolates screened was identified as containing an integron by the screening PCR, and sequence data were obtained across the integron for 34 of 50 (68%) of these isolates. In an attempt to study the molecular epidemiology of antimicrobial resistance genes carried within integrons, a comparison of the types of gene cassettes carried by isolates from different patients was made. Adenyltransferase genes conferring resistance to streptomycin and spectinomycin were the predominant gene cassettes amplified in the study. Resistance to trimethoprim was also frequently found to be encoded within integrons. Furthermore, multiple bacterial isolates obtained from one patient over a 5-month period were all shown to carry an integron containing the same single adenyltransferase gene cassette, suggesting that these elements were relatively stable in this case.
Transposons Tn
1696
and Tn
21
and Their Integrons In4 and In2 Have Independent Origins
Authors: Partridge Sally R. , Brown Heidi J. , Stokes H. W. , Hall Ruth M. 
Published: July 2002

ABSTRACT

The first 13.6 kb of the mercury and multidrug resistance transposon Tn
1696
, which includes the class 1 integron In4, has been sequenced. In4 is 8.33 kb long and contains the 5′-conserved segment (5′-CS) and 2.24 kb of the 3′-conserved segment (3′-CS) flanking four integrated cassettes. The 3′-CS region is followed by one full copy and an adjacent partial copy of the insertion sequence IS
6100
flanked, in inverse orientation, by two short segments (123 and 152 bp) from the outer right-hand end of class 1 integrons. This structure is representative of a distinct group of class 1 integrons that differs from In2, found in Tn
21
, and other related class 1 integrons. In4 does not include transposition genes but is bounded by characteristic 25-bp inverted repeats and flanked by a direct duplication of 5 bp of the target sequence, indicating that it was inserted by a transpositional mechanism. In4 lies between the
resII
and
resI
sites of a backbone mercury resistance transposon which is >99.5% identical to Tn
5036
. Although Tn
21
and Tn
1696
are both classified as members of the Tn
21
subfamily of the Tn
3
transposon family, the backbone mercury resistance transposons are only 79 to 96% identical. Tn
21
also contains a region of about 0.7 kb not found in Tn
1696
. The integrons In2 and In4 carrying the antibiotic resistance genes have been inserted at different locations into distinct ancestral mercury resistance transposons. Thus, Tn
21
and Tn
1696
have independent histories and origins. Other transposons (Tn
1403
and Tn
1412
) that include a class 1 integron also have independent origins. In all except Tn
21
, the integron is located within the
res
region of the backbone transposon.
Oxacillinase-Mediated Resistance to Cefepime and Susceptibility to Ceftazidime inPseudomonas aeruginosa
Authors: Aubert Daniel , Poirel Laurent , Chevalier Jacqueline , Leotard Sophie , Pages Jean-Marie , Nordmann Patrice 
Published: July 2002

ABSTRACTPseudomonas aeruginosaclinical isolate SOF-1 was resistant to cefepime and susceptible to ceftazidime. This resistance phenotype was explained by the expression of OXA-31, which shared 98% amino acid identity with a class D β-lactamase, OXA-1. Theoxa-31gene was located on a ca. 300-kb nonconjugative plasmid and on a class 1 integron. No additional efflux mechanism for cefepime was detected inP. aeruginosaSOF-1. Resistance to cefepime and susceptibility to ceftazidime inP. aeruginosawere conferred by OXA-1 as well.
Sputum Itraconazole Concentrations in Cystic Fibrosis Patients
Authors: Sermet-Gaudelus I. , Lesne-Hulin A. , Lenoir G. , Singlas E. , Berche P. , Hennequin C. 
Published: July 2002

ABSTRACT

Itraconazole diffusion in sputum was studied in 11 cystic fibrosis patients with allergic bronchopulmonary aspergillosis. There was a high interindividual variability in sputum itraconazole concentration and sputum/serum drug concentration ratio. Three children had sputum drug concentrations before oral administration that were lower than the itraconazole MIC at which 90% of
Aspergillus fumigatus
strains were inhibited, although their serum drug concentrations were within the therapeutic range.
Activities of Gemifloxacin and Five Other Antimicrobial Agents against
Listeria monocytogenes
and Coryneform Bacteria Isolated from Clinical Samples
Authors: Martı́nez-Martı́nez Luis , Joyanes Providencia , Suárez Ana I. , Perea Evelio J. 
Published: July 2002

ABSTRACT

The in vitro activities of gemifloxacin, ciprofloxacin, ampicillin, doxycycline, gentamicin, and vancomycin were evaluated against 15
Listeria monocytogenes
strains and 205 coryneform bacteria isolated from clinical samples. The percentages of strains inhibited by gemifloxacin at 0.5 μg/ml were 100% (
L. monocytogenes
), 93.3% (
Brevibacterium
spp.), 90% (
Corynebacterium minutissimum
), 42.5% (
Corynebacterium amycolatum
), 20% (
Corynebacterium striatum
), 12.5% (
Corynebacterium jeikeium
), and 10% (
Corynebacterium urealyticum
). One hundred percent of the
L. monocytogenes
strains were inhibited by 0.25 μg of gemifloxacin per ml, whereas 0% of the strains were inhibited by 0.25 μg of ciprofloxacin per ml. Vancomycin at 2 μg/ml inhibited all strains. Doxycycline and gentamicin at 4 μg/ml inhibited 94 and 49% of the strains, respectively, while ampicillin at 0.5, 2, and 8 μg/ml inhibited 24, 61, and 66% of the strains, respectively. It is concluded that gemifloxacin shows good in vitro activity against
L. monocytogenes
and coryneform bacteria except
C. jeikeium
and
C. urealyticum
.
Relationship between Chloroquine Toxicity and Iron Acquisition in
Saccharomyces cerevisiae
Authors: Emerson Lyndal R. , Nau Martin E. , Martin Rodger K. , Kyle Dennis E. , Vahey Maryanne , Wirth Dyann F. 
Published: July 2002

ABSTRACT

Chloroquine is one of the most effective antimalarials, but resistance to it is becoming widespread. However, we do not fully understand either the drug's mode of action or the mechanism of resistance. In an effort to expand our understanding of the mechanism of action and resistance associated with chloroquine, we used
Saccharomyces cerevisiae
as a model eukaryotic system. To aid in the discovery of potential drug targets we applied the transcriptional profiling method to identify genes transcriptionally responsive to chloroquine treatment in
S. cerevisiae
. Among the genes that were differentially expressed with chloroquine treatment were a number of metal transporters involved in iron acquisition (
SIT1
,
ARN2
,
ARN4
, and
SMF2
). These genes exhibit similar expression patterns, and several are known to be regulated by AFT1, a DNA binding protein, which responds to iron levels in the cell. We investigated the role of chloroquine in iron metabolism by using a variety of approaches, including pharmacological, genetic, and biochemical techniques. For these experiments, we utilized yeast lacking the major iron uptake pathways (
FET3
and
FET4
) and yeast deficient in
SIT1
, encoding the major up-regulated iron siderophore transporter. Our experiments show that yeast genetically or environmentally limited in iron availability has increased sensitivity to chloroquine in pharmacological assays and that the addition of iron rescues these cells from chloroquine killing.
55
FeCl
3
accumulation was inhibited in the presence of chloroquine, and kinetic analysis demonstrated that inhibition was competitive. These results are consistent with deprivation of iron as a mechanism of chloroquine killing in yeast.