bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Four Methods for Determining Lysostaphin Susceptibility of Various Strains of
Staphylococcus aureus
Authors: Kusuma Caroline M. , Kokai-Kun John F. 
Published: July 2005

ABSTRACT

Lysostaphin is an endopeptidase that cleaves the pentaglycine cross-bridges of the staphylococcal cell wall rapidly lysing the bacteria. Recently, lysostaphin has been examined for its potential to treat infections and to clear
Staphylococcus aureus
nasal colonization, requiring a reliable method for determining the lysostaphin susceptibility of strains of
S. aureus
. We compared four methods for determining the lysostaphin susceptibility of 57 strains of methicillin-sensitive
S. aureus
, methicillin-resistant
S. aureus
, vancomycin intermediately susceptible
S. aureus
(VISA), mupirocin-resistant
S. aureus
, and various defined genetic mutants of
S. aureus
. Three reference lysostaphin-resistant
S. aureus
variants were also included in the assays as negative controls. The assays examined included turbidity, MIC, minimum bactericidal concentration (MBC), and disk diffusion assays. All of the strains of
S. aureus
tested, including a VISA strain which had previously been reported to be lysostaphin resistant, were susceptible to lysostaphin by all four methods. The three reference lysostaphin-resistant variants were resistant by all four methods. The disk diffusion assay was the simplest method to differentiate lysostaphin-susceptible
S. aureus
strains from lysostaphin-resistant variants, while the MBC assay could be used as a follow-up assay if required. In the disk diffusion assay, all strains of
S. aureus
tested revealed zones of inhibition of ≥11 mm using a 50-μg lysostaphin disk, while the three reference lysostaphin-resistant
S. aureus
variants had no zones of inhibition. In MBC assays, concentrations of lysostaphin ranging from 0.16 μg/ml to 2.5 μg/ml were found to cause a 3 log or greater drop from the initial CFU of
S. aureus
within 30 min for all strains tested.
Secretion of Proteases by
Pseudomonas aeruginosa
Biofilms Exposed to Ciprofloxacin
Authors: Ołdak Ewa , Trafny Elżbieta A. 
Published: July 2005

ABSTRACT

Pseudomonas aeruginosa
proteases are considered important virulence factors which damage host tissues and interfere with host antibacterial defense mechanisms.
P. aeruginosa
biofilm cells are not completely killed by antibacterials, and therefore this study addresses the question whether ciprofloxacin attenuates the virulence of biofilm communities by abolishing their secretion of proteases. The surviving cells of the colony biofilms studied, despite their cyclical exposure to four doses of ciprofloxacin at bactericidal concentrations (one dose a day), still secreted active proteases to the environment surrounding the biofilms. The biofilm cells secreted elastase B (LasB) over the duration of the experiments as confirmed by Western immunoblot analysis. The colony biofilms did not secrete LasA—a protease with staphylolytic activity. The same profiles on zymogram gels with gelatin were observed for the proteases secreted by both ciprofloxacin-exposed and unexposed (control) biofilms. Total proteolytic activities of the colony biofilms studied were significantly reduced after exposure to ciprofloxacin at bactericidal concentrations—after 96 h of exposure they dropped to 38% for the strain intermediate resistant to ciprofloxacin and to 65% for the strain highly resistant to the antibiotic, relative to the control biofilms. The surviving cells of the colony biofilms after their release into a fresh medium displayed transient increased resistance to ciprofloxacin compared to their planktonic counterparts.
Systemic Antibacterial Activity of Novel Synthetic Cyclic Peptides
Authors: Dartois Véronique , Sanchez-Quesada Jorge , Cabezas Edelmira , Chi Ellen , Dubbelde Chad , Dunn Carrie , Granja Juan , Gritzen Colleen , Weinberger Dana , Ghadiri M. Reza , Parr Thomas R. 
Published: July 2005

ABSTRACTCyclic peptides with an even number of alternatingd,l-α-amino acid residues are known to self-assemble into organic nanotubes. Such peptides previously have been shown to be stable upon protease treatment, membrane active, and bactericidal and to exert antimicrobial activity againstStaphylococcus aureusand other gram-positive bacteria. The present report describes the in vitro and in vivo pharmacology of selected members of this cyclic peptide family. The intravenous (i.v.) efficacy of six compounds with MICs of less than 12 μg/ml was tested in peritonitis and neutropenic-mouse thigh infection models. Four of the six peptides were efficacious in vivo, with 50% effective doses in the peritonitis model ranging between 4.0 and 6.7 mg/kg against methicillin-sensitiveS. aureus(MSSA). In the thigh infection model, the four peptides reduced the bacterial load 2.1 to 3.0 log units following administration of an 8-mg/kg i.v. dose. Activity against methicillin-resistantS. aureuswas similar to MSSA. The murine pharmacokinetic profile of each compound was determined following i.v. bolus injection. Interestingly, those compounds with poor efficacy in vivo displayed a significantly lower maximum concentration of the drug in serum and a higher volume of distribution at steady state than compounds with good therapeutic properties.S. aureuswas unable to easily develop spontaneous resistance upon prolonged exposure to the peptides at sublethal concentrations, in agreement with the proposed interaction with multiple components of the bacterial membrane canopy. Although additional structure-activity relationship studies are required to improve the therapeutic window of this class of antimicrobial peptides, our results suggest that these amphipathic cyclicd,l-α-peptides have potential for systemic administration and treatment of otherwise antibiotic-resistant infections.
Safety, Tolerability, and Pharmacokinetics of Micafungin (FK463) in Febrile Neutropenic Pediatric Patients
Authors: Seibel Nita L. , Schwartz Cindy , Arrieta Antonio , Flynn Patricia , Shad Aziza , Albano Edith , Keirns James , Lau Wendi M. , Facklam David P. , Buell Donald N. , Walsh Thomas J. 
Published: July 2005

ABSTRACT
Micafungin (FK463) is a new parenteral echinocandin. A multicenter, phase I, open-label, sequential-group dose escalation study was conducted to assess the safety, tolerability, and pharmacokinetics of micafungin in neutropenic pediatric patients. A total of 77 patients stratified by age (2 to 12 and 13 to 17 years) received micafungin. Therapy was initiated at 0.5 mg/kg per day and escalated to higher dose levels of 1.0, 1.5, 2.0, 3.0, and 4.0 mg/kg per day. Micafungin was administered within 24 h of initiating broad-spectrum antibacterial antibiotics for the new onset of fever and neutropenia. The most common overall adverse events in the study population were diarrhea (19.5%), epistaxis (18.2%), abdominal pain (16.9%), and headache (16.9%). Nine patients (12%) experienced adverse events considered by the investigator to be possibly related to the study drug. The most common related events were diarrhea, vomiting, and headache, all occurring in two patients each. There was no evidence of a dose-limiting toxicity as defined within the prespecified criteria of this clinical protocol. There was one death during the study due to septic shock. The pharmacokinetic profiles for micafungin over the 0.5- to 4.0-mg/kg dose range demonstrated dose linearity. Clearance, volume of distribution, and half-life remained relatively constant over the dose range and did not change with repeated administration. The overall plasma pharmacokinetic profile was similar to that observed in adults. However, there was an inverse relation between age and clearance. For patients 2 to 8 years old, clearance was approximately 1.35 times that of patients ≥9 years of age. In summary, micafungin over a dosage range between 0.5 and 4.0 mg/kg/day in 77 febrile neutropenic pediatric patients displayed linear pharmacokinetics and increased clearance as a function of decreasing age.
Anti-Human Immunodeficiency Virus Type 1 Activity and Resistance Profile of 2′,3′-Didehydro-3′-Deoxy-4′-Ethynylthymidine In Vitro
Authors: Nitanda Takao , Wang Xin , Kumamoto Hiroki , Haraguchi Kazuhiro , Tanaka Hiromichi , Cheng Yung-Chi , Baba Masanori 
Published: July 2005

ABSTRACT
2′,3′-Didehydro-3′-deoxy-4′-ethynylthymidine (4′-Ed4T) has been identified as a novel nucleoside analog with potent and selective anti-human immunodeficiency virus type 1 (HIV-1) activity and weak cytotoxicity in cell cultures. 4′-Ed4T proved to be 5- to 10-fold more active than its structurally related compound, stavudine (d4T). However, the drug resistance profile of 4′-Ed4T was different from those of d4T and other existing HIV-1 nucleoside reverse transcriptase inhibitors (NRTIs). Approximately 6- to 11-fold decreases in susceptibility to 4′-Ed4T were observed for HIV-1 carrying NRTI-associated mutations (D67N, K70R, T215F, and K219Q) or the lamivudine (3TC)-resistant mutation M184V. In contrast, the susceptibility of the virus carrying the K65R mutation or the multidrug-resistant mutation with the Q151M complex (A62V, V75I, F77L, F116Y, and Q151M) was not altered. Furthermore, the activity of 4′-Ed4T appeared to be enhanced in the presence of K103N, a major nonnucleoside reverse transcriptase inhibitor-resistant mutation. Although 4′-Ed4T was 4.5- to 17.5-fold less active against multidrug-resistant clinical isolates than against a reference strain isolated from a treatment-naïve patient, it was still inhibitory to these isolates at low concentrations. Analysis of 4′-Ed4T-resistant HIV-1 obtained through in vitro selection revealed that the virus was also resistant to 3TC and had two amino acid mutations (P119S and T165A) in addition to the M184V mutation. Since 4′-Ed4T has increased anti-HIV-1 activity, decreased cytotoxicity, and a different resistance profile, it should be considered for further development as a new member of NRTIs.
Hypermutation Is a Key Factor in Development of Multiple-Antimicrobial Resistance inPseudomonas aeruginosaStrains Causing Chronic Lung Infections
Authors: Maciá María D. , Blanquer David , Togores Bernat , Sauleda Jaume , Pérez José L. , Oliver Antonio 
Published: July 2005

ABSTRACTPseudomonas aeruginosais the most relevant pathogen producing chronic lung infections in patients with chronic underlying diseases such as cystic fibrosis (CF), bronchiectasis, and chronic obstructive pulmonary disease (COPD). Hypermutable (or mutator)P. aeruginosastrains, characterized by increased (up to 1,000-fold) spontaneous mutation rates due to alterations of the DNA mismatch repair (MMR) system have been found at high frequencies in the lungs of CF patients, but their role in other chronic processes is still unknown. Sixty-twoP. aeruginosaisolates from 30 patients with underlying non-CF chronic respiratory diseases (22 with bronchiectasis and 8 with COPD) and documented chronic infection were studied. Antibiotic susceptibility profiles and mutation frequencies were determined, and complementation assays using the cloned wild-typemutSgene and molecular epidemiology studies (pulsed-field electrophoresis, [PFGE]) were performed with these strains. Thirty-three (53%) of the isolates were hypermutable, and 17 (57%) of the 30 patients were colonized by hypermutable strains. Strains from 11 of the 17 patients were found to be defective in the MMRmutSgene by complementation assays. Interpatient transmission of strains was ruled out by PFGE. Multiple-antimicrobial resistance was documented in 42% of the hypermutable strains in contrast to 0% resistance in the nonhypermutable strains (P< 0.0001). HypermutableP. aeruginosastrains are extremely prevalent in chronic infections in contrast to what has been described in acute processes, suggesting a role of hypermutation in bacterial adaptation for long-term persistence. Furthermore, hypermutation is found to be a key factor for the development of multiple-antimicrobial resistance, and therefore these findings are expected to have important consequences for the treatment of chronic infections.
Azithromycin Inhibits the Formation of Flagellar Filaments without Suppressing Flagellin Synthesis in
Salmonella enterica
Serovar Typhimurium
Authors: Matsui Hidenori , Eguchi Masahiro , Ohsumi Katsufumi , Nakamura Akio , Isshiki Yasunori , Sekiya Kachiko , Kikuchi Yuji , Nagamitsu Tohru , Masuma Rokuro , Sunazuka Toshiaki , Omura Satoshi 
Published: July 2005

ABSTRACT

The present study shows that a sub-MIC of the macrolide antibiotic azithromycin (AZM) diminishes the virulence function of
Salmonella enterica
serovar Typhimurium. We first constructed an AZM-resistant strain (MS248) by introducing
ermBC
, an erythromycin ribosome methylase gene, into serovar Typhimurium. The MIC of AZM for MS248 exceeded 100 μg/ml. Second, we managed to determine the efficacy with which a sub-MIC of AZM reduced the virulence of MS248 in vitro. On the one hand, AZM (10 μg/ml) in the culture medium was unable to inhibit the total protein synthesis, growth rate, or survival within macrophages of MS248. On the other hand, AZM (10 μg/ml) reduced MS248's swarming and swimming motilities in addition to its invasive activity in Henle-407 cells. Electron micrographs revealed no flagellar filaments on the surface of MS248 after overnight growth in L broth supplemented with AZM (10 μg/ml). However, immunoblotting analysis showed that flagellin (FliC) was fully synthesized within the bacterial cells in the presence of AZM (10 μg/ml). In contrast, the same concentration of AZM reduced the export of FliC to the culture medium. These results indicate that a sub-MIC of AZM was able to affect the formation of flagellar filaments, specifically by reducing the amount of flagellin exported from bacterial cells, but it was not involved in suppressing the synthesis of flagellin. Unfortunately, AZM treatment was ineffective against murine salmonellosis caused by MS248.
Selection of a Macaque Fab with Framework Regions Like Those in Humans, High Affinity, and Ability To Neutralize the Protective Antigen (PA) of
Bacillus anthracis
by Binding to the Segment of PA between Residues 686 and 694
Authors: Laffly Emmanuelle , Danjou Ludivine , Condemine Florence , Vidal Dominique , Drouet Emmanuel , Lefranc Marie-Paule , Bottex Chantal , Thullier Philippe 
Published: July 2005

ABSTRACT

Human anthrax infection cannot always be treated successfully by antibiotics, as highlighted by recent bioterrorist attacks; thus, adjunct therapies are clearly needed for the future. There is a particular need to further develop adjunct therapies that can neutralize secreted toxins, such as antibodies directed towards the 83-kDa protective antigen (PA
83
). In the absence of human donors, we immunized a macaque (
Macaca fascicularis
) with PA
83
to obtain such antibodies suitable as an adjunct therapy for human anthrax infection. By using bone marrow as a template, we PCR amplified specific Fab-encoding genes and cloned them as an immune library (10
7
clones). We isolated a high-affinity (equilibrium dissociation constant [

K
D

], 3.4 nM), highly neutralizing (50% inhibitory concentration, 5.6 ± 0.13 nM) Fab (designated 35PA
83
) from this library by panning. Its epitope was localized by Pepscan analysis between residues 686 and 694 of PA
83
and is part of the region which directly interacts with the cell receptor. 35PA
83
may thus neutralize the anthrax toxin by competing directly for its receptor. The genes encoding 35PA
83
were similar to those of a human immunoglobulin germ line and were assigned to subgroups of human V, (D), or J genes by IMGT/V-QUEST analysis. The 35PA
83
framework regions were 92% identical to a representative allele of each subgroup. When compared to framework regions coded by related human germ line genes, only 2 of 74 (VH) or 75 (VK) analyzed amino acids of 35PA
83
have different chemical characteristics. A very high degree of identity with human framework regions makes 35PA
83
well suited for expression as a whole primatized immunoglobulin G and demonstrates the practicality of using macaque Fabs when immunized human plasma cell donors are not available.
Amino Acid Residues That Contribute to Substrate Specificity of Class A β-Lactamase SME-1
Authors: Majiduddin Fahd K. , Palzkill Timothy 
Published: July 2005

ABSTRACT
Carbapenem antibiotics are used as antibiotics of last resort because they possess a broad spectrum of antimicrobial activity and are not easily hydrolyzed by β-lactamases. Recently, class A enzymes, such as the SME-1, NMC-A, and IMI-1 β-lactamases, have been identified with the capacity to hydrolyze carbapenem antibiotics. Traditional class A β-lactamases, such as TEM-1 and SHV-1, are unable to hydrolyze carbapenem antibiotics and exhibit some differences in sequence from those that are able to hydrolyze carbapenem antibiotics. The positions that differ may contribute to the unique substrate specificity of the class A carbapenemase SME-1. Codons in the SME-1 gene representing residues 104, 105, 132, 167, 237, and 241 were randomized by site-directed mutagenesis, and functional mutants were selected for the ability to hydrolyze imipenem, ampicillin, or cefotaxime. Although several positions are important for hydrolysis of β-lactam antibiotics, no single position was found to uniquely contribute to carbapenem hydrolysis. The results of this study support a model whereby the carbapenemase activity of SME-1 is due to a highly distributed set of interactions that subtly alter the structure of the active-site pocket.
Establishment of a Superficial Skin Infection Model in Mice by Using
Staphylococcus aureus
and
Streptococcus pyogenes
Authors: Kugelberg Elisabeth , Norström Tobias , Petersen Thomas K. , Duvold Tore , Andersson Dan I. , Hughes Diarmaid 
Published: July 2005

ABSTRACT

A new animal model for the purpose of studying superficial infections is presented. In this model an infection is established by disruption of the skin barrier by partial removal of the epidermal layer by tape stripping and subsequent application of the pathogens
Staphylococcus aureus
and
Streptococcus pyogenes
. The infection and the infection route are purely topical, in contrast to those used in previously described animal models in mice, such as the skin suture-wound model, where the infection is introduced into the deeper layers of the skin. Thus, the present model is considered more biologically relevant for the study of superficial skin infections in mice and humans. Established topical antibiotic treatments are shown to be effective. The procedures involved in the model are simple, a feature that increases throughput and reproducibility. This new model should be applicable to the evaluation of novel antimicrobial treatments of superficial infections caused by
S. aureus
and
S. pyogenes
.
Triazine Inhibits
Toxoplasma gondii
Tachyzoites In Vitro and In Vivo
Authors: Mui Ernest J. , Jacobus David , Milhous Wilbur K. , Schiehser Guy , Hsu Honghue , Roberts Craig W. , Kirisits Michael J. , McLeod Rima 
Published: July 2005

ABSTRACT

The triazine WR99210 [4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(2,4,5-trichlorophenoxypropyloxy)-1,3,5 triazine] inhibits
Toxoplasma gondii
in vitro at nanomolar levels (
P
< 0.05). The 50% inhibitory concentration (IC
50
) was approximately 50 nM. It is a potent inhibitor in vitro and is also effective in vivo. Administration of WR99210 parenterally (i.e., intraperitoneally) reduced the mean number of RH strain tachyzoites present in peritoneal fluid substantially 4 days after intraperitoneal infection of mice. There was a mean of approximately 35 million parasites in control mice as contrasted with approximately 2 million parasites in mice treated with 1.25 mg WR99210/kg of body weight in a representative experiment (
P
< 0.05). In addition the prodrug PS-15 N′-[3-(2,4, 5-trichlorophenoxy)propyloxy]-N9-(1-methylethyl) imidocarbonimidicdiamide is converted to 4,6-diamino-1,2-dihydro-2,2-dimethyl-1-(2,4,5-trichlorophenoxypropyloxy)-1,3,5 triazine in vivo when the prodrug is administered orally. PS-15 administered by gavage also reduced intraperitoneal RH strain
T. gondii
tachyzoite numbers. WR99210 has high efficacy and relatively low toxicity because of its substantial effect on
T. gondii
dihydrofolate reductase (DHFR) but not the mammalian host DHFR. Amino acid sequences of
T. gondii
,
Plasmodium falciparum
, and
Homo sapiens
DHFRs were compared. It is of interest that of the DHFR amino acids considered to be interacting with WR99210 in
P. falciparum
within interatomic distances within 3 to 5 Å, four of eight were shared with
T. gondii
DHFR.
H. sapiens
also shared four amino acids thought to be interacting with WR99210. Efficacy of intraperitoneal administration of WR99210 and peroral administration of PS-15 demonstrate the potential usefulness of this class of compounds in treatment of toxoplasmosis administered either parenterally or perorally. The recent development program for this class of antimicrobials as antimalarials makes our proof of principle of improved efficacy of triazines (compared with the gold standard treatment, pyrimethamine) against
T. gondii
especially promising.
TAK-220, a Novel Small-Molecule CCR5 Antagonist, Has Favorable Anti-Human Immunodeficiency Virus Interactions with Other Antiretrovirals In Vitro
Authors: Tremblay Cécile L. , Giguel Françoise , Guan Yongbiao , Chou Ting-Chao , Takashima Katsunori , Hirsch Martin S. 
Published: July 2005

ABSTRACT
TAK-220 is a CCR5 antagonist, part of the new class of anti-human immunodeficiency virus type 1 (anti-HIV-1) entry inhibitors. We evaluated the anti-HIV-1 interactions between TAK-220 and various antiretrovirals in vitro. Synergy was observed with all drugs at the 90 and 95% inhibitory concentrations. The favorable drug interactions observed suggest that further clinical evaluation is warranted.
First Detection of a Carbapenem-Hydrolyzing Metalloenzyme in Two
Enterobacteriaceae
Isolates in Spain
Authors: Tórtola M. Teresa , Lavilla Susana , Miró Elisenda , González Juan José , Larrosa Nieves , Sabaté Montserrat , Navarro Ferran , Prats Guillermo 
Published: July 2005

ABSTRACT

Two strains of
Enterobacteriaceae
,
Escherichia coli
and
Klebsiella pneumoniae
, producing VIM-1 were isolated for the first time in Spain. In both strains,
bla
VIM-1
was found to be carried on a gene cassette inserted into a class 1 integron. The
bla
VIM-1
-containing integron was located on a transferable plasmid.
In Vitro Synergistic Interaction between Amphotericin B and Micafungin against
Scedosporium
spp
Authors: Yustes Clara , Guarro Josep 
Published: July 2005

ABSTRACT

The in vitro interaction between amphotericin B and micafungin against 36 isolates of
Scedosporium
spp. has been evaluated using checkerboard assays and the minimal effective concentration endpoint. Synergy was found for 82.4% of
Scedosporium prolificans
isolates and for 31.6% of
Scedosporium apiospermum
isolates. Antagonism was not observed.
Antimicrobial Activity and Spectrum of PPI-0903M (T-91825), a Novel Cephalosporin, Tested against a Worldwide Collection of Clinical Strains
Authors: Sader Helio S. , Fritsche Thomas R. , Kaniga Koné , Ge Yigong , Jones Ronald N. 
Published: July 2005

ABSTRACT

PPI-0903M is a novel
N
-phosphono-type cephalosporin active against oxacillin-resistant staphylococci and many other gram-positive organisms. This study evaluated the in vitro activity and spectrum of PPI-0903M against 1,478 recent clinical isolates collected from 80 medical centers (22 countries). PPI-0903M demonstrated broader in vitro activity against gram-positive bacteria, particularly against multidrug-resistant staphylococci and streptococci of current clinical concern, than currently available extended-spectrum cephalosporins while maintaining similar activity against gram-negative pathogens.