bluuebunny/crossref_metadata_2025 huggingface dataset:
Cellular Pharmacokinetics and Pharmacodynamics of the Glycopeptide Antibiotic Oritavancin (LY333328) in a Model of J774 Mouse Macrophages
Authors: Van Bambeke Françoise , Carryn Stéphane , Seral Cristina , Chanteux Hugues , Tyteca Donatienne , Mingeot-Leclercq Marie-Paule , Tulkens Paul M.
Published: July 2004

The intracellular pharmacokinetics and pharmacodynamics of oritavancin (LY333328) were studied in cultured cells. Oritavancin was avidly accumulated by J774 and THP-1 macrophages and rat fibroblasts and to a lesser extent by LLC-PK1 and Caco-2 cells. In J774 macrophages, the level of accumulation reached a plateau (at 370-fold the extracellular concentration) within 24 h and was partly defeated by a rise in serum protein levels. Efflux was incomplete (with a plateau at two-thirds of the original level at 6 h). In short-term kinetic studies, oritavancin uptake was linear for up to 4 h (as was the case for horseradish peroxidase and small latex beads, used as markers of the fluid phase and adsorptive endocytosis, respectively), which was in contrast to azithromycin and chloroquine uptake (which accumulate in cells by diffusion and segregation). The rates of clearance of oritavancin and latex beads were comparable (150 and 120 μl × mg of protein−1× h−1, respectively) and were approximately 200 times higher than that of horseradish peroxidase. Oritavancin accumulation was partially reduced by monensin but was unaffected by acidic pH (these conditions abolished chloroquine accumulation). Cell-associated oritavancin was found in lysosomal fractions after homogenization of J774 macrophages and fractionation by isopycnic centrifugation. Oritavancin was bactericidal against intracellularStaphylococcus aureus(phagolysosomal infection) but was unable to control the intracellular growth ofListeria monocytogenes(cytosolic infection), even though its cellular concentration largely exceeded the MIC (0.02 mg/liter) and minimal bactericidal concentration (2 mg/liter). We conclude that oritavancin enters cells by adsorptive endocytosis (favored by its lipophilic side chain and/or the presence of three protonatable amines), which drives it to lysosomes, where it exerts antibiotic activity.
Pilot Randomized Double-Blind Trial of Treatment ofMycobacterium ulceransDisease (Buruli Ulcer) with Topical Nitrogen Oxides
Authors: Phillips R. , Adjei O. , Lucas S. , Benjamin N. , Wansbrough-Jones M.
Published: July 2004

Mycobacterium ulceransdisease (Buruli ulcer) is a serious ulcerating skin disease which is common in many tropical countries. Standard treatment, by extensive excision and skin grafting, is not available in rural communities where the disease is common. We evaluated the efficacy and safety of treatment with topical nitrogen oxides. Thirty-seven patients with a clinical diagnosis of Buruli ulcer caused byM. ulceransdisease were randomly assigned to one of two groups. In one group, two creams containing sodium nitrite (6%, wt/wt) or citric acid monohydrate (9%, wt/wt) were applied daily for 6 weeks, while the other group received a placebo. In the second 6 weeks, both groups received the nitrogen oxide-generating combination of creams. Treatment was continued for another 4 weeks for patients whose ulcers were not healed after 12 weeks. The ulcer surface area was monitored by weekly tracings made by assessors blinded to the treatment. In the first 6 weeks, patients on sodium nitrite and citric acid monohydrate (group I, active treatment) showed a rapid decrease in ulcer size from 28.6 ± 5.6 cm2(mean ± standard error) to 12.6 ± 3.2 cm2, a decrease significantly greater than that in group II (from 15.3 ± 3.1 to 11.7 ± 3.7 cm2;P= 0.03). Five ulcers in the placebo group enlarged during this period, compared with one in the active group. In the second 6 weeks (both groups on active treatment), the rates of healing were similar for the two groups and there was a significant reduction in ulcer size in group II (previously on placebo) compared to the first 6 weeks. Yellow pigmentation of the skin, which disappeared 3 days after treatment was stopped, was the only side effect to date. We conclude that creams releasing nitrogen oxides increase the healing rate of ulcers caused byM. ulceransinfection with minimal adverse events. This is the first controlled trial of any form of therapy which demonstrates efficacy in treating this disease.
Synergy of Daptomycin with Oxacillin and Other β-Lactams against Methicillin-Resistant
Staphylococcus aureus
Authors: Rand Kenneth H. , Houck Herbert J.
Published: July 2004

We previously observed marked synergy between daptomycin and both rifampin and ampicillin against vancomycin-resistant enterococci (VRE). Because the synergy between daptomycin and ampicillin was observed for 100% of VRE strains with high-level ampicillin resistance (ampicillin MIC of ≥128 μg/ml), we looked for synergy between daptomycin and other β-lactams against 18 strains of methicillin-resistant
Staphylococcus aureus
(MRSA) by employing a time-kill method using Mueller-Hinton broth supplemented to 50 mg of Ca
2+
/liter. All strains were resistant to oxacillin (16 of 18 strains were resistant at drug concentrations of ≥256 μg/ml), and all strains were susceptible to daptomycin (the MIC at which 90% of the tested isolates were inhibited was 1 μg/ml). Daptomycin was tested at concentrations of 2, 1, 0.5, 0.25, 0.125, and 0.0625 μg/ml alone or in combination with oxacillin at a fixed concentration of 32 μg/ml. Synergy was found for all 18 strains with daptomycin at one-half the MIC in combination with 32 μg of oxacillin/ml, and synergy was found for 11 of 18 strains (61%) with daptomycin at one-fourth the MIC or less in combination with oxacillin. At 24 h, the daptomycin-oxacillin combination with daptomycin at one-half the MIC showed bactericidal activity against all 18 strains, and the combination with one-fourth the daptomycin MIC showed bactericidal activity against 9 of 18 strains. We also used a novel screening method to look for synergy between daptomycin and other β-lactams. In this approach, daptomycin was incorporated into Ca
2+
-supplemented Mueller-Hinton agar at subinhibitory concentrations, and synergy was screened by comparing test antibiotic Kirby-Bauer disks on agar with and without daptomycin. By this method, daptomycin with ampicillin-sulbactam, ticarcillin-clavulanate, or piperacillin-tazobactam showed synergy comparable to or greater than daptomycin with oxacillin. For seven of the eight strains tested, time-kill studies confirmed synergy between daptomycin and ampicillin-sulbactam with ampicillin in the range of 2 to 8 μg/ml. The combination of daptomycin and β-lactams may be useful for the treatment of MRSA infection, but further studies are needed to elucidate the mechanisms and to determine the in vivo efficacy of the combination.
Inhibition of Hepatitis C Virus Replication by Arsenic Trioxide
Authors: Hwang Der-Ren , Tsai Yuan-Chin , Lee Jin-Ching , Huang Kuo-Kuei , Lin Ren-Kuo , Ho Chia-Hua , Chiou Jeng-Min , Lin Ying-Ting , Hsu John T. A. , Yeh Chau-Ting
Published: July 2004

Hepatitis C virus (HCV) is a serious global problem, and present therapeutics are inadequate to cure HCV infection. In the present study, various antiviral assays show that As
2
O
3
at submicromolar concentrations is capable of inhibiting HCV replication. The 50% effective concentration (EC
50
) of As
2
O
3
required to inhibit HCV replication was 0.35 μM when it was determined by a reporter-based HCV replication assay, and the EC
50
was below 0.2 μM when it was determined by quantitative reverse transcription-PCR analysis. As
2
O
3
did not cause cellular toxicity at this concentration, as revealed by an MTS [3-(4,5-dimethylthiozol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] assay. A combination of As
2
O
3
and alpha interferon exerted synergistic effects against HCV, as revealed by a multiple linear logistic model and isobologram analysis. Furthermore, in an alternative HCV antiviral system that may recapitulate additional steps involved in HCV infection and replication, As
2
O
3
at 0.3 μM totally abolished the HCV signal, whereas alpha interferon at a high dose (5,000 IU/ml) only partially suppressed the HCV signal. The study highlights the indications for use of a novel class of anti-HCV agent. Further elucidation of the exact antiviral mechanism of As
2
O
3
may lead to the development of agents with potent activities against HCV or related viruses.
Effect of Amoxicillin Use on Oral Microbiota in Young Children
Authors: Ready D. , Lancaster H. , Qureshi F. , Bedi R. , Mullany P. , Wilson M.
Published: July 2004

Dental plaque samples from 40 children were screened for the presence of bacteria resistant to amoxicillin. Fifteen children had used amoxicillin and 25 had not used any antibiotic in the 3 months prior to sample collection. All (100%) of the children harbored amoxicillin-resistant oral bacteria. The median percentage of the total cultivable oral microbiota resistant to amoxicillin was 2.4% (range, 0.1 to 14.3%) in children without amoxicillin use and 10.9% (range, 0.8 to 97.3%) in children with amoxicillin use, with the latter value being significantly higher (
P
< 0.01). A total of 224 amoxicillin-resistant bacteria were isolated and comprised three main genera:
Haemophilus
spp.,
Streptococcus
spp., and
Veillonella
spp. The biodiversity of the amoxicillin-resistant microbiota was similar among the isolates from children with and without previous antibiotic use. The amoxicillin MIC at which 90% of the isolates were inhibited for isolates from children who had used amoxicillin in the previous 3 months was higher (64 mg liter
−1
) than that obtained for the isolates from subjects who had not used antibiotics (16 mg liter
−1
). The majority of the amoxicillin-resistant isolates (65%) were also resistant to at least one of the three antibiotics tested (penicillin, erythromycin, and tetracycline), with resistance to penicillin (51% of isolates) being the most frequently encountered. However, significantly more (
P
< 0.05) of the amoxicillin-resistant isolates from subjects with previous amoxicillin use were also resistant to erythromycin. This study has demonstrated that a diverse collection of amoxicillin-resistant bacteria is present in the oral cavity and that the number, proportions, MICs, and resistance to erythromycin can significantly increase with amoxicillin use.
Ribosomal P0 Protein Domain Involved in Selectivity of Antifungal Sordarin Derivatives
Authors: Santos C. , Rodríguez-Gabriel M. A. , Remacha M. , Ballesta J. P. G.
Published: July 2004

The ribosomal stalk protein P0 is involved in the susceptibility to the antifungal sordarin derivatives, as reported for a number of
Saccharomyces cerevisiae
resistant mutants. Mammals and some lower eukaryotes are naturally resistant to these compounds. It is shown here that expression in
S. cerevisiae
of the ribosomal protein P0 from
Homo sapiens
and from other sordarin-resistant organisms results in a decrease in the sensitivity of the cells to an agent of this class. To further characterize the P0 region responsible for inducing sordarin resistance, a series of protein chimeras containing complementary regions of the human and yeast P0 proteins were constructed and expressed in yeast. The chimeras complement the absence of the native yeast P0 except in chimeras containing the human P0 carboxyl-terminal domain. Resistance to sordarins was found to be associated with the presence of an HsP0 amino acid sequence comprising P118 to F138, which unexpectedly led to higher resistance than the presence of the complete human P0. A comparison of the corresponding region in P0 from yeast and sordarin-insensitive organisms, followed by site-directed mutagenesis, indicates that residues in positions 119, 124, and 126 have an important role in determining resistance to sordarins. Moreover, since sordarins block the eukaryotic elongation factor 2 (EF2) function, the P0 region affecting sordarin susceptibility must correspond to EF2-interacting domains of the ribosomal stalk protein, which affects the drug-binding site in the elongation factor.
Novel Azasterols as Potential Agents for Treatment of Leishmaniasis and Trypanosomiasis
Authors: Orenes Lorente Silvia , Rodrigues Juliany C. F. , Jiménez Jiménez Carmen , Joyce-Menekse Miranda , Rodrigues Carlos , Croft Simon L. , Yardley Vanessa , de Luca-Fradley Kate , Ruiz-Pérez Luis M. , Urbina Julio , de Souza Wanderley , González Pacanowska Dolores , Gilbert Ian H.
Published: July 2004

This paper describes the design and evaluation of novel azasterols as potential compounds for the treatment of leishmaniasis and other diseases caused by trypanosomatid parasites. Azasterols are a known class of (
S
)-adenosyl-
l
-methionine: Δ
24
-sterol methyltransferase(24-SMT) inhibitors in fungi, plants, and some parasitic protozoa. The compounds prepared showed activity at micromolar and nanomolar concentrations when tested against
Leishmania
spp. and
Trypanosoma
spp. The enzymatic and sterol composition studies indicated that the most active compounds acted by inhibiting 24-SMT. The role of the free hydroxyl group at position 3 of the sterol nucleus was also probed. When an acetate was attached to the 3β-OH, the compounds did not inhibit the enzyme but had an effect on parasite growth and the levels of sterols in the parasite, suggesting that the acetate group was removed in the organism. Thus, an acetate group on the 3β-OH may have application as a prodrug. However, there may be an additional mode(s) of action for these acetate derivatives. These compounds were shown to have ultrastructural effects on
Leishmania amazonensis
promastigote membranes, including the plasma membrane, the mitochondrial membrane, and the endoplasmic reticulum. The compounds were also found to be active against the bloodstream form (trypomastigotes) of
Trypanosoma brucei rhodesiense
, a causative agent of African trypanosomiasis.
Modulation of Fibronectin Adhesins and Other Virulence Factors in a Teicoplanin-Resistant Derivative of Methicillin-Resistant
Staphylococcus aureus
Authors: Renzoni Adriana , Francois Patrice , Li Dongmei , Kelley William L. , Lew Daniel P. , Vaudaux Pierre , Schrenzel Jacques
Published: July 2004

The impact of glycopeptide resistance on the molecular regulation of
Staphylococcus aureus
virulence and attachment to host tissues is poorly documented. We compared stable teicoplanin-resistant methicillin-resistant
S. aureus
(MRSA) strain 14-4 with its teicoplanin-susceptible MRSA parent, strain MRGR3, which exhibits a high degree of virulence in a rat model of chronic foreign body MRSA infection. The levels of fibronectin-mediated adhesion and surface display of fibronectin-binding proteins were higher in teicoplanin-resistant strain 14-4 than in its teicoplanin-susceptible parent or a teicoplanin-susceptible revertant (strain 14-4rev) that spontaneously emerged during tissue cage infection. Quantitative reverse transcription-PCR (qRT-PCR) showed four- and twofold higher steady-state levels of
fnbA
and
fnbB
transcripts, respectively, in strain 14-4 than in its teicoplanin-susceptible counterparts. Analysis of global regulatory activities by qRT-PCR revealed a strong reduction in the steady-state levels of RNAIII and RNAII in the teicoplanin-resistant strain compared to in its teicoplanin-susceptible counterparts. In contrast,
sarA
mRNA levels were more than fivefold higher in strain 14-4 than in MRGR3 and 14-4rev. Furthermore, the alternative transcription factor sigma B had a higher level of functional activity in the teicoplanin-resistant strain than in its teicoplanin-susceptible counterparts, as evidenced by significant increases in both the sigma B-dependent
asp23
mRNA levels and the
sarA
P3 promoter-derived transcript levels, as assayed by qRT-PCR and Northern blotting, respectively. These data provide further evidence that the emergence of glycopeptide resistance is linked by still poorly understood molecular pathways with significant pleiotropic changes in the expression and regulation of some major virulence genes. These molecular and phenotypic changes may have a profound impact on the bacterial adhesion and colonization properties of such multiresistant organisms.
Relationship between Triclosan and Susceptibilities of Bacteria Isolated from Hands in the Community
Authors: Aiello Allison E. , Marshall Bonnie , Levy Stuart B. , Della-Latta Phyllis , Larson Elaine
Published: July 2004

The possible association between triclosan and bacterial susceptibility to antibiotic was examined among staphylococci and several species of gram-negative bacteria (GNB) isolated from the hands of individuals in a community setting. Hand cultures from individuals randomized to using either antibacterial cleaning and hygiene products (including a hand soap containing 0.2% triclosan) or nonantibacterial cleaning and hygiene products for a 1-year period were taken at baseline and at the end of the year. Although there was no statistically significant association between triclosan MICs and susceptibility to antibiotic, there was an increasing trend in the association the odds ratios (ORs) for all species were compared at baseline (OR = 0.65, 95% confidence interval [95%CI] = 0.33 to 1.27) versus at the end of the year (OR = 1.08, 95%CI = 0.62 to 1.97) and for GNB alone at baseline(OR = 0.66, 95%CI = 0.29 to 1.51) versus the end of year (OR = 2.69, 95%CI = 0.78 to 9.23) regardless of the hand-washing product used. Moreover, triclosan MICs were higher in some of the species compared to earlier reports on household, clinical, and industrial isolates, and some of these isolates had triclosan MICs in the range of concentrations used in consumer products. The absence of a statistically significant association between elevated triclosan MICs and reduced antibiotic susceptibility may indicate that such a correlation does not exist or that it is relatively small among the isolates that were studied. Still, a relationship may emerge after longer-term or higher-dose exposure of bacteria to triclosan in the community setting.
Nucleotide and Amino Acid Polymorphisms at Drug Resistance Sites in Non-B-Subtype Variants of Human Immunodeficiency Virus Type 1
Authors: Turner Dan , Brenner Bluma , Moisi Daniela , Detorio Mervi , Cesaire Raymond , Kurimura Takashi , Mori Haruyo , Essex Max , Maayan Shlomo , Wainberg Mark A.
Published: July 2004

We have compared nucleotide substitutions and polymorphisms at codons known to confer drug resistance in subtype B strains of human immunodeficiency virus type 1 (HIV-1) with similar substitutions in viruses of other subtypes. Genotypic analysis was performed on viruses from untreated individuals. Nucleotide and amino acid diversity at resistance sites was compared with a consensus subtype B reference virus. Among patients with non-subtype B infections, polymorphisms relative to subtype B were observed at codon 10 in protease (PR). These included silent substitutions (CTC→CTT, CTA, TTA) and an amino acid mutation, L10I. Subtype A viruses possessed a V179I substitution in reverse transcriptase (RT). Subtype G viruses were identified by silent substitutions at codon 181 in RT (TAT→TAC). Similarly, subtype A/G viruses were identified by a substitution at position 67 in RT (GAC→GAT). Subtype C was distinguished by silent substitutions at codons 106 (GTA→GTG) and 219 (AAA→AAG) in RT and codon 48 (GGG→GGA) in PR. Variations relative to subtype B were seen at RT position 215 (ACC→ACT) for subtypes A and A/E. These substitutions and polymorphisms reflect different patterns of codon usage among viruses of different subtypes. However, the existence of different subtypes may only rarely affect patterns of drug resistance-associated mutations.
Possible Mechanism of Miltefosine-Mediated Death of
Leishmania donovani
Authors: Verma Navin K. , Dey Chinmoy S.
Published: July 2004

Miltefosine causes leishmanial death, but the possible mechanism(s) of action is not known. The mode of action of miltefosine was investigated in vitro in
Leishmania donovani
promastigotes as well as in extra- and intracellular amastigotes. Here, we demonstrate that miltefosine induces apoptosis-like death in
L. donovani
based on observed phenomena such as nuclear DNA condensation, DNA fragmentation with accompanying ladder formation, and in situ labeling of DNA fragments by the terminal deoxyribonucleotidyltransferase-mediated dUTP-biotin nick end labeling method. Understanding of miltefosine-mediated death will facilitate the design of new therapeutic strategies against
Leishmania
parasites.
Emergence of
Streptococcus pneumoniae
with Very-High-Level Resistance to Penicillin
Authors: Schrag Stephanie J. , McGee Lesley , Whitney Cynthia G. , Beall Bernard , Craig Allen S. , Choate Miriam E. , Jorgensen James H. , Facklam Richard R. , Klugman Keith P.
Published: July 2004

Penicillin resistance threatens the treatment of pneumococcal infections. We used sentinel hospital surveillance (1978 to 2001) and population-based surveillance (1995 to 2001) in seven states in the Active Bacterial Core surveillance of the Emerging Infections Program Network to document the emergence in the United States of invasive pneumococcal isolates with very-high-level penicillin resistance (MIC ≥ 8 μg/ml). Very-high-level penicillin resistance was first detected in 1995 in multiple pneumococcal serotypes in three regions of the United States. The prevalence increased from 0.56% (14 of 2,507) of isolates in 1995 to 0.87% in 2001 (
P
= 0.03), with peaks in 1996 and 2000 associated with epidemics in Georgia and Maryland. For a majority of the strains the MICs of amoxicillin (91%), cefuroxime (100%), and cefotaxime (68%), were ≥8 μg/ml and all were resistant to at least one other drug class. Pneumonia (50%) and bacteremia (36%) were the most common clinical presentations. Factors associated with very highly resistant infections included residence in Tennessee, age of <5 or ≥65 years, and resistance to at least three drug classes. Hospitalization and case fatality rates were not higher than those of other pneumococcal infection patients; length of hospital stay was longer, controlling for age. Among the strains from 2000 and 2001, 39% were related to Tennessee
23F
-4 and 35% were related to England
14-
9. After the introduction of the pneumococcal conjugate vaccine, the incidence of highly penicillin resistant infections decreased by 50% among children <5 years of age. The emergence, clonality, and association of very-high-level penicillin resistance with multiple drug resistance requires further monitoring and highlights the need for novel agents active against the pneumococcus.
Activities of Different Fluoroquinolones against
Bacillus anthracis
Mutants Selected In Vitro and Harboring Topoisomerase Mutations
Authors: Grohs Patrick , Podglajen Isabelle , Gutmann Laurent
Published: July 2004

Three sets of mutants of
Bacillus anthracis
resistant to fluoroquinolones were selected on ciprofloxacin and moxifloxacin in a stepwise manner from a nalidixic acid-resistant but fluoroquinolone-susceptible plasmidless strain harboring a Ser85Leu GyrA mutation. A high level of resistance to fluoroquinolones could be obtained in four or five selection steps. In each case, ParC was the secondary target. However, in addition to the GyrA mutation, expression of high-level resistance required (i) in the first set of mutants, active drug efflux associated with a mutation in the QRDR of ParC; (ii) in the second set, two mutations in the QRDR of ParC associated with a mutation in GyrB; and (iii) in the third set, two QRDR mutations, one in ParC and one in GyrA. Interestingly, several selection steps occurred without obvious mutations in the QRDR of any topoisomerase, thereby implying the existence of other resistance mechanisms. Among the fluoroquinolones tested, garenoxacin showed the best activity.
Pharmacodynamics of Telavancin (TD-6424), a Novel Bactericidal Agent, against Gram-Positive Bacteria
Authors: Hegde Sharath S. , Reyes Noe , Wiens Tania , Vanasse Nicole , Skinner Robert , McCullough Julia , Kaniga Koné , Pace John , Thomas Roger , Shaw Jeng-Pyng , Obedencio Glen , Judice J. Kevin
Published: July 2004

Telavancin (TD-6424) is a novel lipoglycopeptide that produces rapid and concentration-dependent killing of clinically relevant gram-positive organisms in vitro. The present studies evaluated the in vivo pharmacodynamics of telavancin in the mouse neutropenic thigh (MNT) and mouse subcutaneous infection (MSI) animal models. Pharmacokinetic-pharmacodynamic studies in the MNT model demonstrated that the 24-h area under the concentration-time curve (AUC)/MIC ratio was the best predictor of efficacy. Telavancin produced dose-dependent reduction of thigh titers of several organisms, including methicillin-susceptible
Staphylococcus aureus
(MSSA) and methicillin-resistant
Staphylococcus aureus
(MRSA), penicillin-susceptible and -resistant strains of
Streptococcus pneumoniae
, and vancomycin-resistant
Enterococcus faecalis
. The 50% effective dose (ED
50
) estimates for telavancin ranged from 0.5 to 6.6 mg/kg of body weight (administered intravenously), and titers were reduced by up to 3 log
10
CFU/g from pretreatment values. Against MRSA ATCC 33591, telavancin was 4- and 30-fold more potent (on an ED
50
basis) than vancomycin and linezolid, respectively. Against MSSA ATCC 13709, telavancin was 16- and 40-fold more potent than vancomycin and nafcillin, respectively. Telavancin, vancomycin, and linezolid were all efficacious and more potent against MRSA ATCC 33591 in the MSI model compared to the MNT model. This deviation in potency was, however, disproportionately greater for vancomycin and linezolid than for telavancin, suggesting that activity of telavancin is less affected by the immune status. The findings of these studies collectively suggest that once-daily dosing of telavancin may provide an effective approach for the treatment of clinically relevant infections with gram-positive organisms.
Susceptibility to Thrombin-Induced Platelet Microbicidal Protein Is Associated with Increased Fluconazole Efficacy against Experimental Endocarditis Due to
Candida albicans
Authors: Yeaman Michael R. , Cheng Darwin , Desai Bhavesh , Kupferwasser Leon I. , Xiong Yan-Qiong , Gank Kimberly D. , Edwards John E. , Bayer Arnold S.
Published: July 2004

Platelet microbicidal proteins (PMPs) are believed to be integral to host defense against endovascular infection. We previously demonstrated that susceptibility to thrombin-induced PMP 1 (tPMP-1) in vitro negatively influences
Candida albicans
virulence in the rabbit model of infective endocarditis (IE). This study evaluated the relationship between in vitro tPMP-1 susceptibility (tPMP-1
s
) or resistance (tPMP-1
r
) and efficacy of fluconazole (FLU) therapy of IE due to
C. albicans. Candida
IE was established in rabbits with either tPMP-1
s
or tPMP-1
r
strains. Treatment groups received FLU (100 mg/kg/day) intraperitoneally for 7 or 14 days; control animals received no therapy. At these time points, cardiac vegetations, kidneys, and spleens were quantitatively cultured to assess fungal burden. At both 7 and 14 days and in all target tissues, the extent of candidal clearance by FLU was greater in animals infected with the tPMP-1
s
strain than in those infected with the tPMP-1
r
strain. These differences were statistically significant in the spleen and kidney. Corroborating these in vivo data, FLU (a candidastatic agent), in combination with tPMP-1, exerted an enhanced fungicidal effect in vitro against tPMP-1
s
and tPMP-1
r
C. albicans
, with the extent of this effect greatest against the tPMP-1
s
strain. Collectively, these results support the concept that tPMP-1 susceptibility contributes to the net efficacy of FLU against
C. albicans
IE in vivo, particularly in tissues in which platelets and tPMP-1 likely play significant roles in host defense.
Emergence in Italy of a
Neisseria meningitidis
Clone with Decreased Susceptibility to Penicillin
Authors: Stefanelli Paola , Fazio Cecilia , Neri Arianna , Sofia Tonino , Mastrantonio Paola
Published: July 2004

A rise in invasive diseases due to
Neisseria meningitidis
C:2b:P1.5 with decreased penicillin susceptibility occurred in Italy during the last 2 years. Real-time PCR identified the Pen
i
phenotype, and the
penA
sequence revealed the mosaicism of the gene. Molecular analyses assigned the isolates to a single emergent clone of the hypervirulent A4 cluster.
In Vitro Activities of Ravuconazole and Four Other Antifungal Agents against Fluconazole-Resistant or -Susceptible Clinical Yeast Isolates
Authors: Cuenca-Estrella Manuel , Gomez-Lopez Alicia , Mellado Emilia , Garcia-Effron Guillermo , Rodriguez-Tudela Juan L.
Published: July 2004

The activities of ravuconazole and four other antifungal agents were tested against a collection of 1,796 clinical yeast isolates, including fluconazole-susceptible and -resistant strains. Ravuconazole was active against the majority of fluconazole-resistant isolates; but for 102 of 562 (18%) resistant isolates, mainly
Candida tropicalis
,
Candida glabrata
, and
Cryptococcus neoformans
, ravuconazole MICs were ≥1 μg/ml.
Omiganan Pentahydrochloride (MBI 226), a Topical 12-Amino-Acid Cationic Peptide: Spectrum of Antimicrobial Activity and Measurements of Bactericidal Activity
Authors: Sader Helio S. , Fedler Kelley A. , Rennie Robert P. , Stevens Shelley , Jones Ronald N.
Published: July 2004

The activity of omiganan pentahydrochloride (formerly MBI 226; a synthetic cationic peptide) was assessed against 1,437 recent clinical bacterial isolates and 214 recent clinical yeast isolates. The omiganan was highly active, and minimal bactericidal concentrations or minimal fungicidal concentrations were either equal to or two- to fourfold higher than MICs. Kill curve experiments showed a clear pattern of bactericidal activity.
Inhibitory Activities of Colicins against
Escherichia coli
Strains Responsible for Postweaning Diarrhea and Edema Disease in Swine
Authors: Stahl Chad H. , Callaway Todd R. , Lincoln Leslie M. , Lonergan Steven M. , Genovese Kenneth J.
Published: July 2004

The efficacies of colicins E1 and N against
Escherichia coli
strains responsible for postweaning diarrhea and edema disease, two of the most prevalent disease problems for pigs in the United States, were determined in vitro. These proteins may provide an environmentally sound means for the prevention of these infections in swine.
In Vitro Activity and Potency of an Intravenously Injected Antimicrobial Peptide and Its
dl
Amino Acid Analog in Mice Infected with Bacteria
Authors: Braunstein Amir , Papo Niv , Shai Yechiel
Published: July 2004

We report that intravenous injection (3 mg/kg of body weight twice daily) of a diastereomer (containing 33%
d
amino acids) of an antimicrobial peptide, K
6
L
9
(LKLLKKLLKKLLKLL-NH
2
), but not the all-
l
-amino-acid parental peptide, cures neutropenic mice infected with gentamicin-sensitive
Pseudomonas aeruginosa
and gentamicin-resistant
Acinetobacter baumannii
bacteria. Various biophysical experiments suggest a membranolytic-like effect.
In Vitro Killing ofMycobacterium ulceransby Acidified Nitrite
Authors: Phillips R. , Kuijper S. , Benjamin N. , Wansbrough-Jones M. , Wilks M. , Kolk A. H. J.
Published: July 2004

Mycobacterium ulcerans, which causes Buruli ulcer, was exposed to acidified nitrite or to acid alone for 10 or 20 min. Killing was rapid, and viable counts were reduced below detectable limits within 10 min of exposure to 40 mM acidified nitrite.M. ulceransis highly susceptible to acidified nitrite in vitro.
Lack of Activity of Orally Administered Clofazimine against IntracellularMycobacterium tuberculosisin Whole-Blood Culture
Authors: Janulionis Ernestas , Sofer Carolina , Song Ho-Yeon , Wallis Robert S.
Published: July 2004

The activity of oral clofazimine against intracellularMycobacterium tuberculosiswas compared to that of ofloxacin in healthy volunteers by the use of whole-blood cultures. Clofazimine was inactive whether it was tested alone or combined with other drugs that are used to treat multidrug-resistant tuberculosis, despite a total dose of 2 g. Kanamycin was the most active drug tested.
Pharmacokinetics of Intravenous Itraconazole in Stable Hemodialysis Patients
Authors: Mohr John F. , Finkel Kevin W. , Rex John H. , Rodriguez Jose R. , Leitz Gerhard J. , Ostrosky-Zeichner Luis
Published: July 2004

The pharmacokinetics of intravenous itraconazole (ITC) was studied in dialysis patients. Dialysis had no effect on the half-life and clearance of ITC or OH-ITC. However, dialysis allowed the clearance of hydroxypropyl-β-cyclodextrin (HP-β-CD). The area under the concentration-time curve from time zero to infinity (AUC0-∞) for HP-β-CD administered before dialysis was lower than the AUC0-∞when it was administered after dialysis (P< 0.01). Administration of ITC intravenously just prior to hemodialysis appears to produce adequate systemic exposures of ITC and OH-ITC while allowing dialysis clearance of HP-β-CD. Studies of multiple administrations are warranted.
Effect of Granulocyte Colony-Stimulating Factor Combination Therapy on Efficacy of Posaconazole (SCH56592) in an Inhalation Model of Murine Pulmonary Aspergillosis
Authors: Patera Andriani C. , Menzel Frederick , Jackson Craig , Brieland Joan K. , Halpern Judy , Hare Roberta , Cacciapuoti Anthony , Loebenberg David
Published: July 2004

Using an inhalation model of pulmonary aspergillosis, we observed modest differences in the survival rates of mice treated with granulocyte colony-stimulating factor (G-CSF) and posaconazole (POS) and those treated with POS alone. This finding is in contrast to a previous report that suggested that G-CSF had a significant antagonistic effect on the antifungal activity of POS.
High Prevalence of Extended-Spectrum β-Lactamase-Producing Strains among Blood Isolates of
Enterobacter
spp. Collected in a Tertiary Hospital during an 8-Year Period and Their Antimicrobial Susceptibility Patterns
Authors: Pai Hyunjoo , Hong Jung Yun , Byeon Jeong-Hum , Kim Yun-Kyung , Lee Hoan-Jong
Published: July 2004

Of 72 blood isolates of
Enterobacter
spp. collected over an 8-year period, 50% (36 of 72) were derepressed or partially derepressed AmpC mutants. The extended-spectrum β-lactamase (ESBL) production rate was 43% (31 of 72 isolates), and 67.3% (31 of 46) of extended-spectrum cephalosporin-resistant strains produced ESBLs. Thus, a confirmatory test for ESBL production is necessary for extended-spectrum cephalosporin-resistant
Enterobacter
spp.
Temporin A Soaking in Combination with Intraperitoneal Linezolid Prevents Vascular Graft Infection in a Subcutaneous Rat Pouch Model of Infection with
Staphylococcus epidermidis
with Intermediate Resistance to Glycopeptides
Authors: Giacometti Andrea , Cirioni Oscar , Ghiselli Roberto , Orlando Fiorenza , D'Amato Giuseppina , Kamysz Wojciech , Mocchegiani Federico , Sisti Valerio , Silvestri Carmela , Łukasiak Jerzy , Rocchi Marco , Saba Vittorio , Scalise Giorgio
Published: July 2004

The efficacy of linezolid and temporin A in the prevention of prosthetic graft infection due to methicillin-resistant
Staphylococcus epidermidis
with intermediate resistance to glycopeptides was investigated in a subcutaneous rat pouch model. Linezolid and temporin A, alone or combined, greatly reduced the bacterial numbers compared to the effect with control drugs.
In Vitro Activities of Telithromycin, Linezolid, and Quinupristin-Dalfopristin against
Streptococcus pneumoniae
with Macrolide Resistance Due to Ribosomal Mutations
Authors: Farrell David J. , Morrissey Ian , Bakker Sarah , Buckridge Sylvie , Felmingham David
Published: July 2004

To date, 86 of 7,746 macrolide-resistant
Streptococcus pneumoniae
isolates from 1999 to 2002 PROTEKT (Prospective Resistant Organism Tracking and Epidemiology for the Ketolide Telithromycin) surveillance studies were negative for methylase and efflux mechanisms. Mutations in 23S rRNA or the genes encoding riboprotein L4 or L22 were found in 77 of 86 isolates. Six isolates were resistant to quinupristin-dalfopristin and two were resistant to linezolid, while telithromycin demonstrated good activities against all isolates.
CMY-13, a Novel Inducible Cephalosporinase Encoded by anEscherichia coliPlasmid
Authors: Miriagou V. , Tzouvelekis L. S. , Villa L. , Lebessi E. , Vatopoulos A. C. , Carattoli A. , Tzelepi E.
Published: July 2004

An IncN plasmid (p541) fromEscherichia colicarried aCitrobacter freundii-derived sequence of 4,252 bp which included anampC-ampRregion and was bound by two directly repeated IS26elements.ampCencoded a novel cephalosporinase (CMY-13) with activity similar to that of CMY-2. AmpR was likely functional as indicated in induction experiments.
Remarkable Increase in Central Japan in 2001-2002 of
Neisseria gonorrhoeae
Isolates with Decreased Susceptibility to Penicillin, Tetracycline, Oral Cephalosporins, and Fluoroquinolones
Authors: Ito Masayasu , Yasuda Mitsuru , Yokoi Shigeaki , Ito Shin-ichi , Takahashi Yoshito , Ishihara Satoshi , Maeda Shin-ichi , Deguchi Takashi
Published: July 2004

Four hundred sixty-two clinical isolates of
Neisseria gonorrhoeae
recovered from 1999 through 2002 in central Japan were examined for MICs of antimicrobial agents. The majority was sensitive to ceftriaxone and spectinomycin, but a remarkable increase in isolates with decreased susceptibility to penicillin, tetracycline, oral cephalosporins, and fluoroquinolones was observed from 2001 through 2002.
Antianaerobic Activity of a Novel Fluoroquinolone, WCK 771, Compared to Those of Nine Other Agents
Authors: Peric Mihaela , Jacobs Michael R. , Appelbaum Peter C.
Published: July 2004

Agar dilution MIC methodology was used to compare the activity of WCK 771 with those of ciprofloxacin, levofloxacin, moxifloxacin, gatifloxacin, piperacillin, piperacillin-tazobactam, imipenem, clindamycin, and metronidazole against 350 anaerobes. Overall, the MICs (in micrograms per milliliter) at which 50 and 90%, respectively, of the isolates tested were inhibited were as follows: WCK 771, 0.5 and 2.0; ciprofloxacin, 2.0 and 32.0; levofloxacin, 1.0 and 8.0; gatifloxacin, 0.5 and 4.0; moxifloxacin, 0.5 and 4.0; piperacillin, 2.0 and 64.0; piperacillin-tazobactam, ≤0.125 and 8.0; imipenem, 0.125 and 1.0; clindamycin, 0.125 and 16.0; and metronidazole, 1.0 and >16.0.
Novel Antimalarial Compounds Isolated in a Survey of Self-Medicative Behavior of Wild Chimpanzees in Uganda
Authors: Krief Sabrina , Martin Marie-Thérèse , Grellier Philippe , Kasenene John , Sévenet Thierry
Published: July 2004

Following a veterinary and behavioral survey of chimpanzees from a natural population in Uganda, leaf samples of
Trichilia rubescens
were collected because of the unusual method of ingestion observed. The methanolic crude extract of
T. rubescens
leaves exhibited significant antimalarial activity in vitro. Bioassay-directed fractionation provided two new limonoids, trichirubines A and B. A greater understanding of the role of secondary compounds in the primate diet may be helpful in recovering naturally occurring compounds of medicinal significance for human medicine.
Susceptibility of
Chlamydia trachomatis
to Excipients Commonly Used in Topical Microbicide Formulations
Authors: Lampe M. F. , Rohan L. C. , Skinner M. C. , Stamm W. E.
Published: July 2004

Commonly used “inactive” pharmaceutical excipients were tested in a previously developed minimum cidal concentration assay to assess their ability to kill
Chlamydia trachomatis
topically. Sixteen excipients were evaluated in these studies under various conditions. A range of activities was found among the excipients that could be tested in our assay system.
Expression of Members of the 28-Kilodalton Major Outer Membrane Protein Family ofEhrlichia chaffeensisduring Persistent Infection
Authors: Zhang Jian-zhi , Guo Hong , Winslow Gary M. , Yu Xue-jie
Published: July 2004

The 28-kDa immunodominant outer membrane proteins (P28 OMPs) ofEhrlichia chaffeensisare encoded by a multigene family. As an indirect measure of the in vivo expression of the members of thep28multigene family ofE. chaffeensis, sera from two beagle dogs experimentally infected withE. chaffeensiswere evaluated for the presence of specific antibodies to P28 OMPs by enzyme-linked immunosorbent assay. Antigenic peptides unique to each of the P28s were identified within the first hypervariable region of each P28 OMP. Serological responses to peptides derived from all P28 OMPs were detected from day 30 postinoculation to day 468 and from day 46 until day 159 in the two beagles. Although antibody titers to the peptides fluctuated, the peak response to all of the peptides appeared simultaneously in each dog. The antibody responses to another outer membrane protein ofE. chaffeensis(GP120) showed similar temporal and quantitative changes. These data suggest that the P28 OMPs are expressed concurrently during persistentEhrlichiainfection.
Cleavage of Human Transferrin by
Porphyromonas gingivalis
Gingipains Promotes Growth and Formation of Hydroxyl Radicals
Authors: Goulet Véronique , Britigan Bradley , Nakayama Koji , Grenier Daniel
Published: July 2004

Porphyromonas gingivalis
, a gram-negative anaerobic bacterium associated with active lesions of chronic periodontitis, produces several proteinases which are presumably involved in host colonization, perturbation of the immune system, and tissue destruction. The aims of this study were to investigate the degradation of human transferrin by gingipain cysteine proteinases of
P. gingivalis
and to demonstrate the production of toxic hydroxyl radicals (HO
·
) catalyzed by the iron-containing transferrin fragments generated or by release of iron itself. Analysis by polyacrylamide gel electrophoresis and Western immunoblotting showed that preparations of Arg- and Lys-gingipains of
P. gingivalis
cleave transferrin (iron-free and iron-saturated forms) into fragments of various sizes. Interestingly, gingival crevicular fluid samples from diseased periodontal sites but not samples from healthy periodontal sites contained fragments of transferrin. By using
55
Fe-transferrin, it was found that degradation by
P. gingivalis
gingipains resulted in the production of free iron, as well as iron bound to lower-molecular-mass fragments. Subsequent to the degradation of transferrin, bacterial cells assimilated intracellularly the radiolabeled iron. Growth of
P. gingivalis
ATCC 33277, but not growth of an Arg-gingipain- and Lys-gingipain-deficient mutant, was possible in a chemically defined medium containing 30% iron-saturated transferrin as the only source of iron and peptides, suggesting that gingipains play a critical role in the acquisition of essential growth nutrients. Finally, the transferrin degradation products generated by Arg-gingipains A and B were capable of catalyzing the formation of HO
·
, as determined by a hypoxanthine/xanthine oxidase system and spin trapping-electron paramagnetic resonance spectrometry. Our study indicates that
P. gingivalis
gingipains degrade human transferrin, providing sources of iron and peptides. The iron-containing transferrin fragments or the release of iron itself may contribute to tissue destruction by catalyzing the formation of toxic HO
·
.
Intranasal Coadministration of the Cry1Ac Protoxin with Amoebal Lysates Increases Protection againstNaegleria fowleriMeningoencephalitis
Authors: Rojas-Hernández Saúl , Rodríguez-Monroy Marco A. , López-Revilla Rubén , Reséndiz-Albor Aldo A. , Moreno-Fierros Leticia
Published: July 2004

Cry1Ac protoxin has potent mucosal and systemic adjuvant effects on antibody responses to proteins or polysaccharides. In this work, we examined whether Cry1Ac increased protective immunity against fatalNaegleria fowleriinfection in mice, which resembles human primary amoebic meningoencephalitis. Higher immunoglobulin G (IgG) than IgA anti-N. fowleriresponses were elicited in the serum and tracheopulmonary fluids of mice immunized by the intranasal or intraperitoneal route withN. fowlerilysates either alone or with Cry1Ac or cholera toxin. Superior protection against a lethal challenge with 5 × 104liveN. fowleritrophozoites was achieved for immunization by the intranasal route. Intranasal immunization ofN. fowlerilysates coadministered with Cry1Ac increased survival to 100%; interestingly, immunization with Cry1Ac alone conferred similar protection to that achieved with amoebal lysates alone (60%). When mice intranasally immunized with Cry1Ac plus lysates were challenged with amoebae, both IgG and IgA mucosal responses were rapidly increased, but only the increased IgG response persisted until day 60 in surviving mice. The brief rise in the level of specific mucosal IgA does not exclude the role that this isotype may play in the early defense against this parasite, since higher IgA responses were detected in nasal fluids of mice intranasally immunized with lysates plus either Cry1Ac or cholera toxin, which, indeed, were the treatments that provided the major protection levels. In contrast, serum antibody responses do not seem to be related to the protection level achieved. Both acquired and innate immune systems seem to play a role in host defense againstN. fowleriinfection, but further studies are required to elucidate the mechanisms involved in protective effects conferred by Cry1Ac, which may be a valuable tool to improve mucosal vaccines.
Sequence and Binding Activity of the Autolysin-Adhesin Ami from Epidemic
Listeria monocytogenes
4b
Authors: Milohanic Eliane , Jonquières Renaud , Glaser Philippe , Dehoux Pierre , Jacquet Christine , Berche Patrick , Cossart Pascale , Gaillard Jean-Louis
Published: July 2004

Ami is an autolytic amidase from
Listeria monocytogenes
that is targeted to the bacterial surface via its C-terminal cell wall anchoring (CWA) domain. We recently showed that the CWA domain from Ami of
L. monocytogenes
EGD (serovar 1/2a) (Ami 1/2a) mediated bacterial binding to mammalian cells. Here we studied the sequence and binding properties of Ami from CHUT 82337 (serovar 4b) (Ami 4b). The Ami 4b polypeptide is predicted to be 770 amino acids long (compared with the 917 amino acids of Ami 1/2a from EGD). Ami 1/2a and Ami 4b are almost identical in the N-terminal enzymatic domain (∼98% amino acid identity), but the sequence is poorly conserved in the C-terminal CWA domain, with only ∼54% amino acid identity and eight GW modules in Ami 1/2a compared with six GW modules in Ami 4b. The purified Ami 4b CWA domain efficiently bound serovar 4b bacterial cells and only poorly bound serovar 1/2a bacterial cells. The Ami 4b CWA domain was also significantly less able to bind Hep-G2 human hepatocytic cells than the Ami 1/2a CWA domain. We sequenced the
ami
regions encoding CWA domains of reference strains belonging to the 12
L. monocytogenes
serovars. The phylogenic tree constructed from the sequences yielded a binary division into group I (serovars 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, and 7) and group II (serovars 4a, 4b, 4c, 4d, and 4e). This is the first direct evidence of divergence between serovars 1/2a and 4b in a gene involved in the adhesion of
L. monocytogenes
to mammalian cells, as well as the first demonstration of allelic polymorphism correlated with the somatic antigen in this species.