bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vitro and In Vivo Activities of Fluoroquinolones against
Aeromonas hydrophila
Authors: Ko Wen-Chien , Chiang Shyh-Ren , Lee Hsin-Chun , Tang Hung-Jen , Wang Yin-Yi , Chuang Yin-Ching 
Published: June 2003

ABSTRACT

Aeromonas hydrophila
, an uncommon human pathogen, can cause invasive infections in immunocompromised individuals. As the fluoroquinolones have been shown to be active in vitro against mesophilic aeromonads and clinical experience with the use of fluoroquinolones to treat aeromonads infections is limited, the antimicrobial activities of five selected drugs (ciprofloxacin, gatifloxacin, levofloxacin, lomefloxacin, and moxifloxacin) against
A. hydrophila
were studied in vitro and in mice. The MICs of the fluoroquinolones (except lomefloxacin), cefotaxime, and minocycline for 90% of 64 clinical isolates of
A. hydrophila
tested by the agar dilution method were ≤1 μg/ml. With a clinical cefotaxime-resistant strain, Ah 2743, in an in vitro time-kill study, at an inoculum of 7 × 10
5
CFU/ml incubated with fluoroquinolones, cefotaxime, or minocycline at concentrations equal to twice the MICs, the inhibitory effect lasted for less than 6 h and regrowth occurred thereafter. In an animal model with female BALB/c mice intraperitoneally infected with an inoculum of 1.1 × 10
7
CFU of Ah 2743, more mice in the ciprofloxacin-treated group survived (72.2%) than in the cefotaxime-, minocycline-, or cefotaxime-minocycline-treated group (
P
< 0.00001, log rank test). However, there were similar fatality rates, ranging from 71.4 to 87.5%, among mice treated with any of five fluoroquinolones. With a larger inoculum, 4.9 × 10
7
CFU, mice in the ciprofloxacin-treated group survived longer than those in the minocycline-, cefotaxime-, or cefotaxime-minocycline-treated group (30 h versus 18, 12, and 12 h, respectively [
P
< 0.002, log rank test]). However, in mice infected with cefotaxime-susceptible Ah 2556, ciprofloxacin was as effective as cefotaxime-minocycline. Thus, our results suggest that ciprofloxacin is at least as effective as cefotaxime-minocycline against murine
A. hydrophila
infections, which warrants clinical studies to delineate its role in human infections.
Detection of Inhibition of Bovine Viral Diarrhea Virus by Aromatic Cationic Molecules
Authors: Givens M. Daniel , Dykstra Christine C. , Brock Kenny V. , Stringfellow David A. , Kumar Arvind , Stephens Chad E. , Goker Hakan , Boykin David W. 
Published: June 2003

ABSTRACTBovine viral diarrhea virus (BVDV) is an economically significant pathogen of cattle and a problematic contaminant in the laboratory. BVDV is often used as an in vitro model for hepatitis C virus during drug discovery efforts. Aromatic dicationic molecules have exhibited inhibitory activity against several RNA viruses. Thus, the purpose of this research was to develop and apply a method for screening the aromatic cationic compounds for in vitro cytotoxicity and activity against a noncytopathic strain of BVDV. The screening method evaluated the concentration of BVDV in medium and cell lysates after 72 h of cell culture in the presence of either a 25 or 5 μM concentration of the test compound. Five of 93 screened compounds were selected for further determination of inhibitory (90 and 50%) and cytotoxic (50 and 10%) concentration endpoints. The screening method identified compounds that exhibited inhibition of BVDV at nanomolar concentrations while exhibiting no cytotoxicity at 25 μM concentrations. The leading compounds require further investigation to determine their mechanism of action, in vivo activity, and specific activity against hepatitis C virus.
Allele-Specific
rpoB
PCR Assays for Detection of Rifampin-Resistant
Mycobacterium tuberculosis
in Sputum Smears
Authors: Mokrousov Igor , Otten Tatiana , Vyshnevskiy Boris , Narvskaya Olga 
Published: June 2003

ABSTRACT

We describe an allele-specific PCR assay to detect mutations in three codons of the
rpoB
gene (516, 526, and 531) in
Mycobacterium tuberculosis
strains; mutations in these codons are reported to account for majority of
M. tuberculosis
clinical isolates resistant to rifampin (RIF), a marker of multidrug-resistant tuberculosis (MDR-TB). Three different allele-specific PCRs are carried out either directly with purified DNA (single-step multiplex allele-specific PCR), or with preamplified
rpoB
fragment (nested allele-specific PCR [NAS-PCR]). The method was optimized and validated following analysis of 36 strains with known
rpoB
sequence. A retrospective analysis of the 287 DNA preparations from epidemiologically unlinked RIF-resistant clinical strains from Russia, collected from 1996 to 2002, revealed that 247 (86.1%) of them harbored a mutation in one of the targeted
rpoB
codons. A prospective study of microscopy-positive consecutive sputum samples from new and chronic TB patients validated the method for direct analysis of DNA extracted from sputum smears. The potential of the NAS-PCR to control for false-negative results due to lack of amplification was proven especially useful in the study of these samples. The developed
rpoB
-PCR assay can be used in clinical laboratories to detect RIF-resistant and hence MDR
M. tuberculosis
in the regions with high burdens of the MDR-TB.
Phenotypic and Molecular Characterization of Tetracycline- and Erythromycin-Resistant Strains of
Streptococcus pneumoniae
Authors: Montanari Maria P. , Cochetti Ileana , Mingoia Marina , Varaldo Pietro E. 
Published: June 2003

ABSTRACT

Sixty-five clinical isolates of
Streptococcus pneumoniae
, all collected in Italy between 1999 and 2002 and resistant to both tetracycline (MIC, ≥8 μg/ml) and erythromycin (MIC, ≥1 μg/ml), were investigated. Of these strains, 11% were penicillin resistant and 23% were penicillin intermediate. With the use of the erythromycin-clindamycin-rokitamycin triple-disk test, 14 strains were assigned to the constitutive (cMLS) phenotype of macrolide resistance, 44 were assigned to the partially inducible (iMcLS) phenotype, 1 was assigned to the inducible (iMLS) phenotype, and 6 were assigned to the efflux-mediated (M) phenotype. In PCR assays, 64 of the 65 strains were positive for the tetracycline resistance gene
tet
(M), the exception being the one M isolate susceptible to kanamycin, whereas
tet
(K),
tet
(L), and
tet
(O) were never found. All cMLS, iMcLS, and iMLS isolates had the erythromycin resistance gene
erm
(B), and all M phenotype isolates had the
mef
(A) or
mef
(E) gene. No isolate had the
erm
(A) gene. The
int-Tn
gene, encoding the integrase of the Tn
916
-Tn
1545
family of conjugative transposons, was detected in 62 of the 65 test strains. Typing assays showed the strains to be to a great extent unrelated. Of 16 different serotypes detected, the most numerous were 23F (
n
= 13), 19A (
n
= 10), 19F (
n
= 9), 6B (
n
= 8), and 14 (
n
= 6). Of 49 different pulsed-field gel electrophoresis types identified, the majority (
n
= 39) were represented by a single isolate, while the most numerous type included five isolates. By high-resolution restriction analysis of PCR amplicons with four endonucleases, the
tet
(M) loci from the 64
tet
(M)-positive pneumococci were classified into seven distinct restriction types. Overall, a Tn
1545
-like transposon could reasonably account for tetracycline and erythromycin resistance in the vast majority of the pneumococci of cMLS, iMcLS, and iMLS phenotypes, whereas a Tn
916
-like transposon could account for tetracycline resistance in most M phenotype strains.
Gastric Transitional Zones, Areas whereHelicobacterTreatment Fails: Results of a Treatment Trial Using the Sydney Strain Mouse Model
Authors: van Zanten Sander J. O. Veldhuyzen , Kolesnikow Tassia , Leung Vincent , O'Rourke Jani L. , Lee Adrian 
Published: June 2003

ABSTRACTCurrent combination therapies cureHelicobacter pyloriinfection in 75 to 85% of cases. However, many treatment failures are not explained by antibiotic resistance. Our goal was to explore treatment failures under in vivo conditions by using theH. pyloriSydney strain (SS1) mouse model. Mice infected withH. pylori(SS1) were treated with monotherapies or combination therapies used in human trials. Bacterial levels and distribution of organisms within the stomach were assessed 24 h after treatment to determine clearance and location of treatment failures and 29 days after treatment to determine cure rates. Except for treatment with metronidazole, mono- and dual therapies did not cure infection but resulted in decreases in bacterial levels and differences in distribution within the stomach. In cases of treatment failure when clarithromycin was used, omeprazole and dual therapy with omeprazole and amoxicillin resulted in organisms being cleared from the antrum, but organisms remained in the antrum-body transitional zone. The triple therapies of OMC and bismuth subcitrate, metronidazole, and tetracycline were successful in eradicating infection. Except for metronidazole monotherapy and triple therapy with OAC, there was good correlation between the Sydney strain mouse model and humans with respect to the success of antimicrobial therapy. The antrum-body transitional zone was identified as a sanctuary site in treatment failure. This could result from antimicrobial agents not functioning effectively at this site or bacteria in this location expressing products that protect them against antimicrobial agents. This is the first demonstration of a possible sanctuary site as a reason for failure of therapy.
Multiple-Dose Safety and Pharmacokinetics of Oral Garenoxacin in Healthy Subjects
Authors: Gajjar D. A. , Bello A. , Ge Z. , Christopher L. , Grasela D. M. 
Published: June 2003

ABSTRACT

Garenoxacin (T-3811ME, BMS-284756) is a novel des-F(6) quinolone that has been shown to be effective in vitro against a wide range of clinically important pathogens, including gram-positive and gram-negative aerobes and anaerobes. This study was conducted to evaluate the safety and tolerability of multiple oral doses (100 to 1,200 mg/day) of garenoxacin in healthy subjects and to determine its multiple-dose pharmacokinetics. Forty healthy male and female subjects (18 to 45 years of age) were enrolled in this randomized, double-blind, placebo-controlled, sequential, multiple- and ascending-dose study. Each subject received a once-daily oral dose of garenoxacin (100, 200, 400, 800, or 1,200 mg) or a placebo for 14 days. Blood and urine samples were collected for measurements of garenoxacin by validated liquid chromatography with dual mass spectrometry, and plasma garenoxacin concentration-time data were analyzed by noncompartmental methods. The effects of garenoxacin on
Helicobacter pylori
, psychometric test performance, and electrocardiograms were assessed, as was drug safety. Over the 14 days of dosing, geometric mean peak concentrations of garenoxacin in plasma (
C
max
) at the 100- and 1,200-mg doses were within the ranges of 1.2 to 1.6 and 16.3 to 24 μg/ml, respectively. The corresponding values for the geometric mean area under the concentration-time curve over the dosing interval (AUC

τ

) for garenoxacin in plasma at the 100- and 1,200-mg doses were within the ranges of 11.5 to 15.7 and 180 to 307 μg · h/ml, respectively. Increases in systemic exposure to garenoxacin in terms of AUC and
C
max
were approximately dose proportional over the 100- to 400-mg dose range but demonstrated increases that were somewhat greater than the dose increments at the 800- and 1,200-mg doses. Median values for the time to achieve
C
max
were in the range of 1.13 to 2.50 h for all doses. The mean elimination half-life for garenoxacin in plasma appeared to be independent of dose and ranged from 13.3 to 17.8 h (day 14). Approximately 30 to 50% of an administered garenoxacin dose was excreted unchanged in the urine. At doses of 100 to 400 mg, steady-state concentrations of garenoxacin in plasma appeared to be attained by the fourth dose. Multiple oral doses of garenoxacin were well tolerated and did not demonstrate clinically significant effects on QT
c
or psychometric test results. Garenoxacin administered alone for 14 days at doses of ≥400 mg demonstrated activity against
H. pylori.
These results suggest that multiple once-daily oral doses of garenoxacin of up to 1,200 mg are safe and well tolerated and that the pharmacokinetics of garenoxacin support once-daily administration.
Neuraminidase Sequence Analysis and Susceptibilities of Influenza Virus Clinical Isolates to Zanamivir and Oseltamivir
Authors: McKimm-Breschkin J. , Trivedi T. , Hampson A. , Hay A. , Klimov A. , Tashiro M. , Hayden F. , Zambon M. 
Published: June 2003

ABSTRACT

The influenza virus neuraminidase (NA) inhibitors zanamivir and oseltamivir were introduced into clinical practice in various parts of the world between 1999 and 2002. In order to monitor the potential development of resistance, the Neuraminidase Inhibitor Susceptibility Network was established to coordinate testing of clinical isolates collected through the World Health Organization influenza surveillance network from different regions of the world (M. Zambon and F. G. Hayden, Antivir. Res. 49:147-156, 2001). The present study establishes the baseline susceptibilities prior to and shortly after the introduction of the NA inhibitors. Over 1,000 clinical influenza isolates recovered from 1996 to 1999 were tested. Susceptibilities were determined by enzyme inhibition assays with chemiluminescent or fluorescent substrates with known NA inhibitor-resistant viruses as controls. The 50% inhibitory concentrations (IC
50
s) depended upon the assay method, the drug tested, and the influenza virus subtype. By both assays, the mean zanamivir IC
50
s were 0.76, 1.82, and 2.28 nM for the subtype H1N1 (N1), H3N2 (N2), and B NAs, respectively, and the oseltamivir IC
50
s were 1.2, 0.5, and 8.8 nM for the N1, N2, and B NAs, respectively. The drug susceptibilities of known zanamivir- and oseltamivir-resistant viruses with the NA mutations E119V, R292K, H274Y, and R152K fell well outside the 95% confidence limits of the IC
50
s for all natural isolates. Sequence analysis of the NAs of viruses for which the IC
50
s were above the 95% confidence limits and several control isolates for which the IC
50
s were in the normal range revealed variations in some previously conserved residues, including D151, A203, T225, and E375 (N2 numbering). Known resistance mutations are both influenza virus subtype and drug specific, but there was no evidence of naturally occurring resistance to either drug in any of the isolates.
Molecular Basis for Fungal Selectivity of Novel Antimitotic Compounds
Authors: Lila Thomas , Renau Thomas E. , Wilson Lori , Philips Jay , Natsoulis Georges , Cope M. Jamie , Watkins William J. , Buysse Jerry 
Published: June 2003

ABSTRACT
Compounds that selectively disrupt fungal mitosis have proven to be effective in controlling agricultural pests, but no specific mitotic inhibitor is available for the treatment of systemic mycoses in mammalian hosts. In an effort to identify novel mitotic inhibitors, we used a cell-based screening strategy that exploited the hypersensitivity of a yeast α-tubulin mutant strain to growth inhibition by antimitotic agents. The compounds identified inhibited yeast nuclear division and included one structural class of compounds shown to be fungus specific. MC-305,904 and structural analogs inhibited fungal cell mitosis and inhibited the in vitro polymerization of fungal tubulin but did not block mammalian cell microtubule function or mammalian tubulin polymerization. Extensive analysis of yeast mutations that specifically alter sensitivity to MC-305,904 structural analogs suggested that compounds in the series bind to a site on fungal β-tubulin near amino acid 198. Features of the proposed binding site explain the observed fungal tubulin specificity of the series and are consistent with structure-activity relationships among a library of related compounds.
Quantitative Analysis of Gentamicin, Azithromycin, Telithromycin, Ciprofloxacin, Moxifloxacin, and Oritavancin (LY333328) Activities against Intracellular
Staphylococcus aureus
in Mouse J774 Macrophages
Authors: Seral Cristina , Van Bambeke Françoise , Tulkens Paul M. 
Published: June 2003

ABSTRACT

Using J774 macrophages, the intracellular activities of gentamicin, azithromycin, telithromycin, ciprofloxacin, moxifloxacin, and oritavancin (LY333328) against
Staphylococcus aureus
(strain ATCC 25923) have been quantitatively assessed in a 24-h model.
S. aureus
was positively localized in phagolysosomes by confocal and electron microscopy, and extracellular growth was prevented with 0.5 mg of gentamicin/liter (1× MIC) in controls. When tested at extracellular concentrations equivalent to their maximum concentrations in human serum, all antibiotics except azithromycin caused a significant reduction of the postphagocytosis inoculum within 24 h, albeit to markedly different extents (telithromycin [2 mg/liter], 0.60 log; ciprofloxacin [4.3 mg/liter], 0.81 log; gentamicin [18 mg/liter], 1.21 log; moxifloxacin [4 mg/liter], 1.51 log; oritavancin [25 mg/liter], 3.49 log). Intracellular activities were not systematically related to drug accumulation (apparent cellular-to-extracellular concentration ratios in infected cells: ciprofloxacin, 3.2; gentamicin, 6.8; telithromycin, 8.7; moxifloxacin, 13.4; azithromycin, 50; oritavancin, 348). Intracellular activity was not directly correlated to extracellular activity as measured in broth. Conditions of pH 5 (i.e., mimicking that of phagolysosomes) markedly reduced the activity of gentamicin, azithromycin, and telithromycin (≥32×) and fairly extensively reduced that of ciprofloxacin and moxifloxacin (≥4×) but did not affect oritavancin activity. We conclude that the cellular accumulation of antibiotics is not the only parameter to take into account for intracellular activity but that local environmental conditions (such as pH) and other factors can also prove critical.
Synergistic In Vitro Interactions between Alpha Interferon and Ribavirin against Bovine Viral Diarrhea Virus and Yellow Fever Virus as Surrogate Models of Hepatitis C Virus Replication
Authors: Buckwold Victor E. , Wei Jiayi , Wenzel-Mathers Michelle , Russell Julie 
Published: June 2003

ABSTRACT

Monotherapy of hepatitis C virus infection with either alpha interferon or ribavirin alone is rather ineffective, while the use of the two antivirals together is much more efficacious. In vitro drug-drug combination analysis utilizing related members of the family
Flaviviridae
, bovine viral diarrhea virus and yellow fever virus, revealed significant direct synergistic interactions between these drugs' antiviral activities that might explain this clinical observation.
Inhibitory Effect of NO-Releasing Ciprofloxacin (NCX 976) on
Mycobacterium tuberculosis
Survival
Authors: Ciccone R. , Mariani F. , Cavone A. , Persichini T. , Venturini G. , Ongini E. , Colizzi V. , Colasanti M. 
Published: June 2003

ABSTRACT

Here, we report the antimycobacterial activity of NCX 976, a new molecule obtained adding a NO moiety to the fluoroquinolone ciprofloxacin, on
Mycobacterium tuberculosis
H37Rv strain, both in a cell-free model and in infected human macrophages. Unlike unaltered ciprofloxacin, NCX976 displayed a marked activity also at low-nanomolar concentrations.
Intracellular Release of Nitric Oxide by NCX 972, an NO-Releasing Metronidazole, Enhances In Vitro Killing ofEntamoeba histolytica
Authors: Sannella Anna , Gradoni Luigi , Persichini Tiziana , Ongini Ennio , Venturini Giorgio , Colasanti Marco 
Published: June 2003

ABSTRACTThe activity of NCX 972, a new molecule obtained by adding a nitric oxide (NO) moiety to metronidazole, was tested against six isolates ofEntamoeba histolyticain xenic cultures. NCX 972 released NO into trophozoite cells and enhanced killing of amoebas in a dose- and time-dependent manner compared to metronidazole.
Nonsense Mutations in the
lsa
-Like Gene in
Enterococcus faecalis
Isolates Susceptible to Lincosamides and Streptogramins A
Authors: Dina Julia , Malbruny Brigitte , Leclercq Roland 
Published: June 2003

ABSTRACT

The
lsa
gene confers intrinsic resistance to lincosamides and streptogramins A in
Enterococcus faecalis
, probably by active efflux. The
lsa
-like genes of two clinical isolates of
E. faecalis
susceptible to lincosamides and dalfopristin contained mutations that produced premature termination codons. Revertant mutants were obtained by selection on agar plates containing clindamycin.
Presence of the Tet M Determinant in a Clinical Isolate of
Acinetobacter baumannii
Authors: Ribera Anna , Ruiz Joaquim , Vila Jordi 
Published: June 2003

ABSTRACT

The
tet
(M) gene encodes a protein which is related to tetracycline ribosomal protection, one of the mechanisms of tetracycline resistance. A
tet
(M) gene that is 100% homologous to the
tet
(M) gene of
Staphylococcus aureus
has been found in a clinical isolate of
Acinetobacter baumannii
, which also carries the
tet
(A) gene encoding a tetracycline efflux pump.
Zinc Eluted from Siliconized Latex Urinary Catheters Decreases OprD Expression, Causing Carbapenem Resistance in
Pseudomonas aeruginosa
Authors: Conejo M. Carmen , García Isabel , Martínez-Martínez Luis , Picabea Leandro , Pascual Álvaro 
Published: June 2003

ABSTRACT

The activities of carbapenems against
Pseudomonas aeruginosa
decreased in the presence of siliconized latex urinary catheters (SLUCs). This effect was associated with the loss of OprD. The zinc that eluted from SLUCs is responsible for this phenomenon. We have found that zinc exerts a negative effect on the expression of OprD, the porin responsible for carbapenem entry into
P. aeruginosa
.
Detection of Nucleotide Variability in
rpoB
in both Rifampin-Sensitive and Rifampin-Resistant Strains of
Chlamydia trachomatis
Authors: Dreses-Werringloer Ute , Padubrin Ingrid , Köhler Lars , Hudson Alan P. 
Published: June 2003

ABSTRACT

A 656-bp PCR fragment from
rpoB
was sequenced from five rifampin-resistant
Chlamydia trachomatis
variants selected in vitro from a wild-type parent with a surprising level of genetic variability in this region. Three variants (MIC, 4 μg/ml) showed Ala522→Val in cluster I (codons 507 to 533), which harbors mutations in most rifampin-resistant bacteria. Two high-level resistance variants (MICs, 64 and 256 μg/ml) showed His526→Tyr in cluster I with additional genetic variation, some of which resulted in amino acid substitutions. None of the latter was situated in clusters related to rifampin resistance in other bacteria.
Ribosomal Mutations Conferring Resistance to Macrolides in
Streptococcus pneumoniae
Clinical Strains Isolated in Germany
Authors: Reinert Ralf René , Wild Angela , Appelbaum Peter , Lütticken Rudolf , Cil Murat Yücel , Al-Lahham Adnan 
Published: June 2003

ABSTRACT
Among a collection of 4,281 pneumococcal isolates, 7 strains isolated in Germany had an unusual macrolide resistance phenotype. The isolates were found to have multiple mutations in the 23S rRNA and alterations in the L4 ribosomal protein. One strain had an amino acid alteration in the L22 ribosomal protein.