bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficacy of MK-991 (L-743,872), a Semisynthetic Pneumocandin, in Murine Models of
Pneumocystis carinii
Authors: Powles Mary Ann , Liberator Paul , Anderson Jennifer , Karkhanis Yashwant , Dropinski James F. , Bouffard F. Aileen , Balkovec James M. , Fujioka Hisashi , Aikawa Masamichi , McFadden Diane , Schmatz Dennis
Published: October 2018

In addition to its potent efficacy in animal models against
Candida
sp.,
Aspergillus fumigatus
, and
Histoplasma capsulatum
, the clinical candidate pneumocandin MK-991 (formerly L-743,872) was also extremely potent against
Pneumocystis carinii
in models of immune-compromised animals. MK-991 was approximately 14 times more potent than the original natural product lead, pneumocandin B
0
. The 90% effective dose (ED
90
) of MK-991 for cyst clearance in the rat model for pneumocystis was 0.011 mg/kg of body weight when delivered parenterally for 4 days twice a day (b.i.d.). In a mouse model, under the same experimental parameters, the ED
90
was 0.02 mg/kg. MK-991 was also effective orally, with an ED
90
for cyst clearance of 2.2 mg/kg against acute infection in rats (b.i.d. for 4 days). Complete prevention of
P. carinii
development was achieved in immunocompromised mice at a daily oral dose of 2.25 mg/kg. As reported previously for other pneumocandins and echinocandins, MK-991 selectively prevented the development of
P. carinii
cysts. When used as a prophylactic agent, neither stage of the organism appeared in the lungs of animals. In response to an acute infection, cysts were eliminated rapidly, while trophozoite forms persisted. Despite good efficacy as an oral agent in murine models, the low oral absorption of this class may limit the use of MK-991 to parenteral therapy.
Nucleoside Analog 1592U89 and Human Immunodeficiency Virus Protease Inhibitor 141W94 Are Synergistic In Vitro
Authors: Drusano G. L. , D’Argenio D. Z. , Symonds W. , Bilello P. A. , McDowell J. , Sadler B. , Bye A. , Bilello J. A.
Published: October 2018

The use of combinations of anti-human immunodeficiency virus (anti-HIV) agents targeted to different molecular targets will most likely result in increased viral suppression and may also delay or prevent the emergence of resistant HIV strains. The purpose of the present study was to develop information on the in vitro anti-HIV activities of combinations of the reverse transcriptase inhibitor 1592U89 and the protease inhibitor 141W94 to help guide the choice of dosages in clinical trials. Triplicate in vitro dose-response matrices were prepared with MT-2 cells infected with HIV type 1 (HIV-1) strain IIIB. In order to account for the effects of protein binding, tissue culture medium with 10% fetal bovine serum was supplemented with the human serum proteins α
1
acid glycoprotein (1 mg/ml) and albumin (40 mg/ml). The three-dimensional drug interaction surface for 1592U89 and 141W94 was constructed with the program MacSynergy II. As analyzed relative to a Bliss Independence null reference model, this combination was synergistic, with volumes of synergy exceeding 100 (99% confidence). Analysis of the data set with a fully parametric form of an equation for the quantitation of drug interaction developed by Greco et al. (W. R. Greco, G. Bravo, and J. C. Parsons, Pharmacol. Rev. 47:331–385, 1995) resulted in an interaction term statistically significantly greater than 0.0, indicating true synergy. Both methods concur that this combination is significantly synergistic. These data, with favorable findings from phase I/II trials for each drug alone, suggest that the combination of 1592U89 plus 141W94 should be further evaluated in clinical trials.
Characterization of a PSE-4 Mutant with Different Properties in Relation to Penicillanic Acid Sulfones: Importance of Residues 216 to 218 in Class A β-Lactamases
Authors: Sabbagh Yves , Thériault Esther , Sanschagrin François , Voyer Normand , Palzkill Timothy , Levesque Roger C.
Published: October 2018

Class A β-lactamases are inactivated by the suicide inactivators sulbactam, clavulanic acid, and tazobactam. An examination of multiple alignments indicated that amino acids 216 to 218 differed among class A enzymes. By random replacement mutagenesis of codons 216 to 218 in PSE-4, a complete library consisting of 40,864 mutants was created. The library of mutants with mutations at positions 216 to 218 in PSE-4 was screened on carbenicillin and ampicillin with the inactivator sulbactam; a collection of 14 mutants was selected, and theirblagenes were completely sequenced. Purified wild-type and mutant PSE-4 β-lactamases were used to measure kinetic parameters. One enzyme, V216S:T217A:G218R, was examined for its peculiar pattern of inhibition. There was an increase in theKmfrom 68 μM for the wild type to 271 μM for the mutant for carbenicillin and 33 to 216 μM for ampicillin. Relative to the wild-type PSE-4 enzyme, 37- and 30-fold increases inKivalues were observed for the mutant enzyme for sulbactam and tazobactam, respectively. The results that were obtained suggested that positions 216 to 218 are important for interactions with penicillanic acid sulfone inhibitors. In contrast, V216 and A217 in the TEM-1 class A β-lactamase do not tolerate amino acid residue substitutions. However, for the PSE-4 β-lactamase, 11 of 14 mutants from the library of mutants with mutations at positions 216 to 218 whose sequences were determined had substitutions at position 216 (G, R, A, S) and position 217 (A, S). The data showed the importance of residues 216 to 218 in their atomic interactions with inactivators in the PSE-4 β-lactamase structure.
Salmonella enteritidis
: AmpC Plasmid-Mediated Inducible β-Lactamase (DHA-1) with an
ampR
Gene from
Morganella morganii
Authors: Barnaud Guilene , Arlet Guillaume , Verdet Charlotte , Gaillot Olivier , Lagrange Philippe H. , Philippon Alain
Published: October 2018

DHA-1, a plasmid-mediated cephalosporinase from a single clinical
Salmonella enteritidis
isolate, conferred resistance to oxyimino-cephalosporins (cefotaxime and ceftazidime) and cephamycins (cefoxitin and moxalactam), and this resistance was transferable to
Escherichia coli
HB101. An antagonism was observed between cefoxitin and aztreonam by the diffusion method. Transformation of the transconjugant
E. coli
strain with plasmid pNH5 carrying the
ampD
gene (whose product decreases the level of expression of
ampC
) resulted in an eightfold decrease in the MIC of cefoxitin. A clone with the same AmpC susceptibility pattern with antagonism was obtained, clone
E. coli
JM101(pSAL2-ind), and its nucleotide sequence was determined. It contained an open reading frame with 98.7% DNA sequence identity with the
ampC
gene of
Morganella morganii
. DNA sequence analysis also identified a gene upstream of
ampC
whose sequence was 97% identical to the partial sequence of the
ampR
gene (435 bp) from
M. morganii
. The gene encoded a protein with an amino-terminal DNA-binding domain typical of transcriptional activators of the LysR family. Moreover, the intercistronic region between the
ampC
and
ampR
genes was 98% identical to the corresponding region from
M. morganii
DNA. AmpR was shown to be functional by enzyme induction and a gel mobility-shift assay. An
ampG
gene was also detected in a Southern blot of DNA from the
S. enteritidis
isolate. These findings suggest that this inducible plasmid-mediated AmpC type β-lactamase, DHA-1, probably originated from
M. morganii.
Activities of Gatifloxacin Compared to Those of Seven Other Agents against Anaerobic Organisms
Authors: Ednie Lois M. , Jacobs Michael R. , Appelbaum Peter C.
Published: October 2018

The agar dilution MIC was used to compare activities of gatifloxacin with those of ciprofloxacin, sparfloxacin, trovafloxacin, ampicillin, ampicillin-sulbactam, clindamycin, and metronidazole against 351 anaerobes. Overall MICs at which 50% of the isolates are inhibited and MICs at which 90% of the isolates are inhibited (in micrograms per milliliter) were as follows: gatifloxacin, 0.5 and 4; ciprofloxacin, 2 and 32; sparfloxacin, 2 and 8; trovafloxacin, 1 and 4; ampicillin, 1 and 64; ampicillin-sulbactam, 0.5 and 4; clindamycin, 0.125 and 8; and metronidazole, 1 and >16, respectively. Gatifloxacin MICs were similar to those of trovafloxacin in all organism groups.
Population Pharmacokinetics of Nevirapine, Zidovudine, and Didanosine in Human Immunodeficiency Virus-Infected Patients
Authors: Zhou Xiao-Jian , Sheiner Lewis B. , D’Aquila Richard T. , Hughes Michael D. , Hirsch Martin S. , Fischl Margaret A. , Johnson Victoria A. , Myers Maureen , Sommadossi Jean-Pierre ,   The National Institute of Allergy and Infectious Diseases AIDS Clinical Trials Group Protocol 241 Investigators
Published: October 2018

The population pharmacokinetics of nevirapine (NVP), zidovudine (ZDV), and didanosine (ddI) were evaluated in a total of 175 patients infected with human immunodeficiency virus randomized to receive either a double combination of ZDV plus ddI or a triple combination of NVP plus ZDV plus ddI as a substudy of the AIDS Clinical Trials Group Protocol 241. Levels (approximating 3.5 determinations/patient) of the three drugs in plasma were measured during 44 of a total 48 weeks of study treatment, and a set of potential covariates was available for nonlinear mixed-effect modeling analysis. A one-compartment model with zero-order input and first-order elimination was fitted to the NVP data. Individual oral clearance (CL) and volume of distribution (V) averaged 0.0533 liters/h/kg of body weight and 1.17 liters/kg, respectively. Gender was the only covariate which significantly correlated with the CL of NVP. ZDV and ddI data were described by a two-compartment model with zero-order input and first-order elimination. Individual mean oral CL,VSS(volume of distribution at steady state), andVof ZDV were 1.84 liters/h/kg and 6.68 and 2.67 liters/kg, respectively, with body weight and age as correlates of CL and body weight as a correlate ofVSS. The average individual oral CL,VSS, andVof ddI were 1.64 liters/h/kg and 3.56 and 2.74 liters/kg, respectively, with body weight as a significant correlate of both CL andVSS. The relative bioavailability (F) of ZDV and ddI in the triple combination compared to that in the double combination was also evaluated. No significant effects of the combination regimens on theFof ddI were detected (FTRIPLE= 1.05 andFDOUBLE= 1 by definition), but theFof ZDV was markedly reduced by the triple combination, being only 67.7% of that of the double combination. Large (>50%) intraindividual variability was associated with both ZDV and ddI pharmacokinetics. Individual cumulative area under the plasma drug level-time curve of the three drugs was calculated for the entire study period as a measure of drug exposure based on the individual data and the final-model estimates of structural and statistical parameters.
Limited-Sampling Strategy Models for Itraconazole and Hydroxy-Itraconazole Based on Data from a Bioequivalence Study
Authors: Suarez-Kurtz Guilherme , Bozza Fernando A. , Vicente Flavio L. , Ponte Cristiano G. , Struchiner Claudio J.
Published: October 2018

The extensive interindividual variability in oral bioavailability of itraconazole prompted an assessment of the bioequivalence of two formulations marketed in Brazil, namely, Sporanox (reference) and Traconal (test). Eighteen healthy volunteers received single 200-mg oral doses of each formulation at 2-week intervals in a randomized, crossover protocol. The concentrations of itraconazole and hydroxy-itraconazole in plasma were measured by high-performance liquid chromatography, and the datum points (n= 396) were subsequently used to develop limited-sampling strategy models for estimation of the areas under the curve (AUCs) for both compounds. The 90% confidence intervals for individual percent ratios (test/reference formulations) of the maximum concentration of drug in serum, the AUC from 0 to 48 h and the AUC from time zero to infinity (AUC0–∞) for itraconazole and hydoxy-itraconazole were below the range of 80 to 125%, suggesting that these formulations are not bioequivalent. Linear regression analysis of the AUC0–∞against time and a “jackknife” validation procedure revealed that models based on three sampling times accurately predict (R2, >0.98; bias, <3%; precision, 3 to 7%) the AUC0–∞for each of the four formulation-compound pairs tested. Increasing the number of sampling points to more than three adds little to the accuracy of the estimates of AUC0–∞. The three-point models developed for the reference formulation were validated retrospectively and were found to predict within 2% the AUC0–∞reported in previous studies performed under similar protocols. In conclusion, the data in this study indicate (i) that the tested formulations are not bioequivalent when single doses are compared and (ii) that limited-sampling strategy models based on three points predict accurately the AUC0–∞s for itraconazole and hydroxy-itraconazole and could be a valuable tool in pharmacokinetic and bioequivalence studies of single oral doses of itraconazole.
Activity of HMR 3647 Compared to Those of Six Compounds against 235 Strains of
Enterococcus faecalis
Authors: Hoellman Dianne B. , Lin Gengrong , Jacobs Michael R. , Appelbaum Peter C.
Published: October 2018

Agar dilution was used to test the activities of HMR 3647, erythromycin A, azithromycin, clarithromycin, roxithromycin, clindamycin, and quinupristin-dalfopristin against 235 strains of
Enterococcus faecalis
. HMR 3647 was the most active compound (MICs at which 50 and 90% of the isolates are inhibited [MIC
50
and MIC
90
, respectively] of 0.06 and 4.0 μg/ml, respectively). The MIC
50
and MIC
90
(with the MIC
50
given first and the MIC
90
given second; both in micrograms per milliliter) for other compounds were as follows: 4.0 and >32.0 for erythromycin A, 16.0 and >32.0 for azithromycin, 2.0 and >32 for clarithromycin, 32.0 and >32.0 for roxithromycin, 32.0 and >32.0 for clindamycin, and 8.0 and 16.0 for quinupristin-dalfopristin. All compounds were only bacteriostatic.
Experimental Evaluation of Second-Line Oral Treatments of Visceral Leishmaniasis Caused by
Leishmania infantum
Authors: Gangneux Jean-Pierre , Dullin Michael , Sulahian Annie , Garin Yves Jean-Francois , Derouin Francis
Published: October 2018

In a murine model of
Leishmania infantum
visceral leishmaniasis, metronidazole, ketoconazole, fluconazole, itraconazole, and terbinafine were less effective than antimonial agents in reducing hepatic parasite load. Ketoconazole potentiated the effect of meglumine antimoniate reference therapy through its marked activity against spleen infection.
The New Ketolide HMR3647 Accumulates in the Azurophil Granules of Human Polymorphonuclear Cells
Authors: Miossec-Bartoli Christine , Pilatre Lydie , Peyron Pascale , N’Diaye Elsa-Noah , Collart-Dutilleul Véronique , Maridonneau-Parini Isabelle , Diu-Hercend Anita
Published: October 2018

HMR3647 is a semisynthetic representative of a new group of drugs, the ketolides, derived from erythromycin A. Since macrolides have been shown to accumulate in human polymorphonuclear cells (PMNs), we have investigated the ability of the molecule HMR3647 to enter human PMNs as well as other cell types, such as peripheral blood mononuclear cells and cell lines of hematopoietic and nonhematopoietic origin. In these experiments, HMR3647 was compared to erythromycin A, azithromycin, clarithromycin, and roxithromycin. Our results show that HMR3647 is specifically trapped in PMNs, where it is concentrated up to 300 times. In addition, it is poorly released by these cells, 80% of the compound remaining cell associated after 2 h in fresh medium. By contrast, it is poorly internalized and quickly released by the other cell types studied. This differs from the results obtained with the macrolide molecules, which behaved similarly in the different cells studied. In addition, subcellular fractionation of PMNs allowed us to identify the intracellular compartment where HMR3647 was trapped. In PMNs, more than 75% of the molecule was recovered in the azurophil granule fraction. Similarly, in NB4 cells differentiated into PMN-like cells, almost 60% of the molecules accumulated in the azurophil granule fraction. In addition, when HMR3647 was added to disrupted PMNs, 63% accumulated in the azurophil granules. Therefore, this study shows that the ketolide HMR3647 specifically accumulates in PMN azurophil granules, thus favoring its delivery to bacteria phagocytosed in these cells.
Sparfloxacin Selects Gyrase Mutations in First-Step
Mycoplasma hominis
Mutants, whereas Ofloxacin Selects Topoisonmerase IV Mutations
Authors: Kenny George E. , Young Patrick A. , Cartwright Frank D. , Sjöström Karen E. , Huang Wai M.
Published: October 2018

The role of mutations in the genes for GyrA and ParC in quinolone resistance in
Mycoplasma hominis
was studied. Selection with sparfloxacin gave mutations at GyrA83 (Ser→Leu;
Escherichia coli
numbering) or GyrA87 (Glu→Lys), and mutants had increased levels of resistance to sparfloxacin (8- to 16-fold) but not to ofloxacin. Selection with ofloxacin gave changes at ParC80 (Ser→Ile) or ParC84 (Glu→Lys), and mutants were four- to eightfold more resistant to ofloxacin but not to sparfloxacin. Selection of second-step mutants from strains with ParC mutations with either quinolone yielded double mutants with additional mutations at GyrA83 (Ser→Trp or Ser→Leu) or GyrA87 (Glu→Lys). Second-step selection of GyrA mutants gave additional mutations at ParC80 (Ser→Ile) or ParC84 (Glu→Lys). Two-step mutants showed high levels of resistance to ofloxacin (MICs, 64 to 128 μg/ml) and moderate levels of resistance to sparfloxacin (MICs, 2 to 8 μg/ml). The primary target of ofloxacin in first-step mutants of
Mycoplasma hominis
was ParC, whereas that for sparfloxacin was GyrA.
Trends in Antimicrobial Resistance among Clinical Isolates of the
Bacteroides fragilis
Group from 1992 to 1997 in Montreal, Canada
Authors: Labbé Annie-Claude , Bourgault Anne-Marie , Vincelette Jean , Turgeon Pierre L. , Lamothe François
Published: October 2018

The objective of the present study was to analyze the susceptibility profiles of 911 clinical strains of the
Bacteroides fragilis
group isolated from 1992 to 1997 in our institution in order to monitor susceptibility changes over time. Whereas the rates of resistance to metronidazole, imipenem, piperacillin-tazobactam, ticarcillin-clavulanic acid, penicillin, piperacillin, and cefoxitin remained essentially unchanged, there was a significant increase in the rates of resistance to clindamycin, which rose from 8.2% in 1992 to 19.7% in 1997 (
P
< 0.0004).
Bactericidal Activity and Postantibiotic Effect of Levofloxacin against Anaerobes
Authors: Pendland Susan L. , Diaz-Linares Mariela , Garey Kevin W. , Woodward Jennifer G. , Ryu Seonyoung , Danziger Larry H.
Published: October 2018

The bactericidal activity and postantibiotic effect (PAE) of levofloxacin against nine anaerobes were determined. Levofloxacin at concentrations of the MIC and twice the MIC was bactericidal at 24 h to five of nine and nine of nine strains, respectively. The PAE of levofloxacin following a 2-h exposure ranged from 0.06 to 2.88 h.
Phenotypic Distinction in
Enterococcus faecium
and
Enterococcus faecalis
Strains between Susceptibility and Resistance to Growth-Enhancing Antibiotics
Authors: Butaye Patrick , Devriese Luc A. , Haesebrouck Freddy
Published: October 2018

Susceptibility of
Enterococcus faecium
and
Enterococcus faecalis
strains from animals and foods to growth-promoting antibiotics used in animal feed was tested by the agar dilution technique. Acquired resistance to bacitracin, narasin, tylosin, and virginiamycin was seen for both species, and for
E. faecium
, resistance to avilamycin and avoparcin was also seen. Drawing the distinction between susceptibility and resistance based on frequency distributions of MICs was easy with avoparcin, avilamycin, and tylosin but difficult with virginiamycin and to some extent also with bacitracin and narasin.
Survey of Susceptibilities of
Streptococcus pneumoniae
,
Haemophilus influenzae
, and
Moraxella catarrhalis
Isolates to 26 Antimicrobial Agents: a Prospective U.S. Study
Authors: Thornsberry C. , Ogilvie P. T. , Holley H. P. , Sahm D. F.
Published: October 2018

An antimicrobial susceptibility surveillance study of
Streptococcus pneumoniae
,
Haemophilus influenzae
, and
Moraxella catarrhalis
isolates was performed during the winter of 1996–1997 in order to determine their susceptibilities to 5 fluoroquinolones and 21 other antimicrobial agents. Broth microdilution MICs were determined for 2,752 isolates from 51 U.S. medical centers. Of the 1,276
S. pneumoniae
isolates, 64% were susceptible, 17% were intermediate, and 19% were highly resistant to penicillin. On the basis of the MICs at which 90% of isolates are inhibited and modal MICs, the hierarchy of the five fluoroquinolones from most to least active was grepafloxacin > sparfloxacin > levofloxacin = ciprofloxacin > ofloxacin. For
S. pneumoniae
isolates for which penicillin MICs were elevated, the MICs of the cephalosporins, macrolides, clindamycin, tetracycline, and trimethoprim-sulfamethoxazole were also elevated, but the MICs of the fluoroquinolones, vancomycin, and rifampin were not. The prevalence of penicillin-susceptible pneumococci varied by U.S. Bureau of the Census region (range, 44% in the East South Central region to 75% in the Pacific region). In addition,
S. pneumoniae
isolates from blood were significantly more susceptible to penicillin than those from respiratory, ear, or eye specimens, and pneumococci from patients ≤2 years old were significantly more resistant to penicillin than those from older patients (by chi-square analysis,
P
< 0.05). β-Lactamase was produced by 35% of
H. influenzae
isolates and 93% of
M. catarrhalis
isolates, resulting in increased MICs of amoxicillin and certain cephalosporins. We noted that the antimicrobial resistance patterns of
S. pneumoniae
isolates, which correlate with the penicillin susceptibility phenotype, vary by site of infection, age group of the patient, and geographic source of the isolate.
Effects of Genes Encoding Resistance to Streptogramins A and B on the Activity of Quinupristin-Dalfopristin againstEnterococcus faecium
Authors: Bozdogan Bülent , Leclercq Roland
Published: October 2018

Quinupristin-dalfopristin is a streptogramin combination active against multiply resistantEnterococcus faecium. Among 45E. faeciumisolated from patients in various French hospitals, only two strains were intermediate (MIC = 2 μg/ml) and one,E. faeciumHM1032, was resistant (MIC = 16 μg/ml) to quinupristin-dalfopristin, according to British Society for Antimicrobial Chemotherapy and National Committee for Clinical Laboratory Standards approved breakpoints. The latter strain contained thevgbandsatAgenes responsible for hydrolysis or acetylation of quinupristin and dalfopristin, respectively, and anermBgene (also previously referred to asermAM) encoding a ribosomal methylase. The two intermediate strains had an LSAphenotype characterized by resistance to lincomycin (L), increased MICs (≥8 μg/ml) of dalfopristin (streptogramin A [SA]), and susceptibility to erythromycin and quinupristin. This phenotype was also detected in eight other strains susceptible to quinupristin-dalfopristin. No genes already known and conferring resistance to dalfopristin by acetylation or active efflux were detected in these LSAstrains. Nineteen other strains resistant to erythromycin but susceptible to the quinupristin-dalfopristin combination displayed elevated MICs of quinupristin after induction (from 16 to >128 μg/ml) and containedermBgenes. The effects ofermB,vgb, andsatAgenes on the activity of the streptogramin combination were tested by cloning these genes individually or in various combinations in recipient strains susceptible to quinupristin-dalfopristin,E. faeciumHM1070 andStaphylococcus aureusRN4220. The presence of both thesatAandvgbgenes (regardless of the presence of anermBgene) was necessary to confer full quinupristin-dalfopristin resistance to the host. The same genetic constructs were introduced intoE. faeciumBM4107 which displays a LSAphenotype. Addition of thesatAorvgbgene to this LSAbackground conferred resistance to quinupristin-dalfopristin.
Pharmacokinetics of a Once-Daily Oral Dose of Moxifloxacin (Bay 12-8039), a New Enantiomerically Pure 8-Methoxy Quinolone
Authors: Sullivan John T. , Woodruff Marilyn , Lettieri John , Agarwal Vipin , Krol George J. , Leese Philip T. , Watson Susan , Heller Allen H.
Published: October 2018

The pharmacokinetics, safety, and tolerability of oral moxifloxacin, a new 8-methoxy quinolone, were assessed in a randomized, double-blind, placebo-controlled study in which healthy male and female volunteers received either 400 mg of moxifloxacin once daily (
n
= 10) or a placebo once daily (
n
= 5) for 10 days. Plasma moxifloxacin concentrations on days 1 and 10 were measured by high-performance liquid chromatography and fluorometric detection. Standard pharmacokinetic parameters were estimated by noncompartmental methods. Natural logarithmic estimates for each pharmacokinetic variable of each subject were analyzed by a two-way analysis of variance. Hematology, blood chemistry, vital signs, and adverse events were monitored, and electrocardiograms (ECG) were performed. Plasma moxifloxacin concentrations of predicted therapeutic relevance were achieved in this study. For day 1, the mean maximum concentration of drug in serum (
C
max
) and the area under the concentration-time curve from 0 to 24 h (AUC
0–24
) were 3.4 mg/liter and 30.2 mg · h/liter, respectively. Corresponding means on day 10 were 4.5 mg/liter and 48 mg · h/liter, respectively. On day 10, the mean elimination half-life was approximately 12 h. Plasma moxifloxacin concentrations exceeded the MIC for
Streptococcus pneumoniae
throughout the 24-h dosing period. The day 1 and day 10 mean AUC/MIC ratios were 121 and 192, respectively, and the mean
C
max
/MIC ratios were 13 and 18, respectively. Moxifloxacin was well tolerated; no clinically relevant changes in the standard laboratory tests, vital signs, or ECG were observed. Pharmacokinetic parameters demonstrated linearity, and estimates of pharmacokinetic/pharmacodynamic ratios (AUC/MIC and
C
max
/MIC) indicate that the regimen of 400-mg once daily should be effective for treating a variety of infections. Moxifloxacin was found to be safe and well tolerated in healthy volunteers when it was given as a single daily 400-mg dose for 10 days.
Azithromycin Activities against
Orientia tsutsugamushi
Strains Isolated in Cases of Scrub Typhus in Northern Thailand
Authors: Watt George , Kantipong Pacharee , Jongsakul Krisada , Watcharapichat Pochaman , Phulsuksombati Duangporn
Published: October 2018

Azithromycin was given to mice and humans infected with strains of
Orientia tsutsugamushi
from northern Thailand, where drug-resistant scrub typhus occurs. Azithromycin and doxycycline yielded comparable mouse survival rates (73 and 79%, respectively;
P
> 0.5). Symptoms, signs, and fever in two pregnant women abated rapidly with azithromycin. Prospective human trials are needed.
Efficacy of the Triazole SCH 56592 against
Leishmania amazonensis
and
Leishmania donovani
in Experimental Murine Cutaneous and Visceral Leishmaniases
Authors: Al-Abdely Hail M. , Graybill John R. , Loebenberg David , Melby Peter C.
Published: October 2018

Current therapy for leishmaniasis is unsatisfactory. Efficacious and safe oral therapy would be ideal. We examined the efficacy of SCH 56592, an investigational triazole antifungal agent, against cutaneous infection with
Leishmania amazonensis
and visceral infection with
Leishmania donovani
in BALB/c mice. Mice were infected in the ear pinna and tail with
L. amazonensis
promastigotes and were treated with oral SCH 56592 or intraperitoneal amphotericin B for 21 days. At doses of 60 and 30 mg/kg/day, SCH 56592 was highly efficacious in treating cutaneous disease, and at a dose of 60 mg/kg/day, it was superior to amphotericin B at a dose of 1 mg/kg/day. The means of tail lesion sizes were 0.32 ± 0.12, 0.11 ± 0.06, 0.17 ± 0.07, and 0.19 ± 0.08 mm for controls, SCH 56592 at 60 and 30 mg/kg/day, and amphotericin B recipients, respectively (
P
= 0.0003, 0.005, and 0.01, respectively). Parasite burden in draining lymph nodes confirmed these efficacy findings. In visceral leishmaniasis due to
L. donovani
infection, mice treated with SCH 56592 showed a 0.5- to 1-log-unit reduction in parasite burdens in the liver and the spleen compared to untreated mice. Amphotericin B at 1 mg/kg/day was superior to SCH 56592 in the treatment of visceral infection, with a 2-log-unit reduction in parasite burdens in both the liver and spleen. These studies indicate very good activity of SCH 56592 against cutaneous leishmaniasis due to
L. amazonensis
infection and, to a lesser degree, against visceral leishmaniasis due to
L. donovani
infection in susceptible BALB/c mice.
Proton-Pumping-ATPase-Targeted Antifungal Activity of a Novel Conjugated Styryl Ketone
Authors: Manavathu Elias K. , Dimmock Jonathan R. , Vashishtha Sarvesh C. , Chandrasekar Pranatharthi H.
Published: October 2018

NC1175 (3-[3-(4-chlorophenyl)-2-propenoyl]-4-[2-(4-chlorophenyl)vinylene]-1-ethyl-4-piperidinol hydrochloride) is a novel thiol-blocking conjugated styryl ketone that exhibits activity against a wide spectrum of pathogenic fungi. Incubation of NC1175 with various concentrations of cysteine and glutathione eliminated its antifungal activity in a concentration-dependent fashion. Since NC1175 is a lipophilic compound that has the potential to interact with cytoplasmic membrane components, we examined its effect on the membrane-located proton-translocating ATPase (H
+
-ATPase) of yeast (
Candida albicans
,
Candida krusei
,
Candida guilliermondii
,
Candida glabrata
, and
Saccharomyces cerevisiae
) and
Aspergillus
(
Aspergillus fumigatus
,
Aspergillus niger
,
Aspergillus flavus
, and
Aspergillus nidulans
) species. The glucose-induced acidification of external medium due to H
+
-ATPase-mediated expulsion of intracellular protons by these fungi was measured in the presence of several concentrations of the drug. NC1175 (12.5 to 50 μM) inhibited acidification of external medium by
Candida
,
Saccharomyces
, and
Aspergillus
species in a concentration-dependent manner. Vanadate-inhibited hydrolysis of ATP by membrane fractions of
C. albicans
was completely inhibited by 50 μM NC1175, suggesting that the target of action of NC1175 in these fungi may include H
+
-ATPase.
Oral Bioavailability and Pharmacokinetics of Trovafloxacin in Patients with AIDS
Authors: Lacy Melinda K. , Nicolau David P. , Nightingale Charles H. , Geffken Amy , Teng Renli , Vincent John , Quintiliani Richard
Published: October 2018

Trovafloxacin pharmacokinetics were evaluated in 12 subjects with AIDS. By using a randomized design, single 200-mg doses of oral trovafloxacin and intravenous alatrofloxacin were administered. The mean absolute bioavailability was 91%. The pharmacokinetics of trovafloxacin when administered orally as the active form or intravenously as the prodrug (alatrofloxacin) are not altered in subjects with AIDS compared to those in healthy adults.
Population Pharmacokinetics of Lamivudine in Adult Human Immunodeficiency Virus-Infected Patients Enrolled in Two Phase III Clinical Trials
Authors: Moore Katy H. P. , Yuen Geoffrey J. , Hussey Elizabeth K. , Pakes Gary E. , Eron Joseph J. , Bartlett John A.
Published: October 2018

Lamivudine population pharmacokinetics were investigated by using nonlinear mixed-effect modelling (NONMEM) analysis of data from 394 human immunodeficiency virus (HIV)-infected patients treated with lamivudine (150 to 300 mg every 12 h) in two large, phase III clinical efficacy-safety trials, NUCA3001 and NUCA3002. Analyses of 1,477 serum lamivudine concentration determinations showed that population estimates for lamivudine oral clearance (CL/F; 25.1 liters/h) and volume of distribution (V/F; 128 liters) were similar to values previously reported for HIV-infected patients in phase I pharmacokinetic studies. Lamivudine CL/F was significantly influenced by the covariates creatinine clearance and weight and not affected by age, Centers for Disease Control and Prevention (CDC) classification, CD4
+
cell count, HIV type 1 (HIV-1) RNA PCR, or gender and race when CL/F was corrected for differences in patient weight. The population estimate for lamivudine V/F was not significantly influenced by the covariates gender, race, age, weight, renal function, HIV-1 RNA PCR, or CDC classification and CD4
+
cell count when creatinine clearance was included with CL/F in the model. Lamivudine disposition was significantly influenced by renal function. However, as only three patients had an estimated creatinine clearance of <60 ml/min, dosage adjustments for patients with impaired renal function should not be determined based on the population parameters derived in this analysis.
Beneficial Effect of Adjunctive Azithromycin in Treatment of Mucoid
Pseudomonas aeruginosa
Pneumonia in the Murine Model
Authors: Nicolau David P. , Banevicius Mary Anne , Nightingale Charles H. , Quintiliani Richard
Published: October 2018

While a time-kill methodology noted no appreciable improvement in bactericidal activity with the addition of azithromycin (AZM) to a ceftazidime (CAZ) regimen, data from the murine pneumonia model showed that the addition of AZM significantly improved survival compared to treatment with CAZ alone. These data suggest that AZM might be a useful adjunctive therapy in the management of pneumonia resulting from mucoid isolates of
Pseudomonas aeruginosa
.
The Thiocarboxanilide Nonnucleoside Inhibitor UC781 Restores Antiviral Activity of 3′-Azido-3′-Deoxythymidine (AZT) against AZT-Resistant Human Immunodeficiency Virus Type 1
Authors: Borkow Gadi , Arion Dominique , Wainberg Mark A. , Parniak Michael A.
Published: October 2018

N
-[4-Chloro-3-(3-methyl-2-butenyloxy)phenyl]-2-methyl-3-furancarbothioamide (UC781) is an exceptionally potent nonnucleoside inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase. We found that a 1:1 molar combination of UC781 and 3′-azido-3′-deoxythymidine (AZT) showed high-level synergy in inhibiting the replication of AZT-resistant virus, implying that UC781 can restore antiviral activity to AZT against AZT-resistant HIV-1. Neither the nevirapine plus AZT nor the 2′,5′-bis-
O
-(
t
-butyldimethylsilyl)-3′-spiro-5"-(4"-amino-1",2"-oxathiole-2",2"-dioxide plus AZT combinations had this effect. Studies with purified HIV-1 reverse transcriptase (from a wild type and an AZT-resistant mutant) showed that UC781 was a potent inhibitor of the pyrophosphorolytic cleavage of nucleotides from the 3′ end of the DNA polymerization primer, a process that we have proposed to be critical for the phenotypic expression of AZT resistance. Combinations of UC781 plus AZT did not act in synergy to inhibit the replication of either wild-type virus or UC781-resistant HIV-1. Importantly, the time to the development of viral resistance to combinations of UC781 plus AZT is significantly delayed compared to the time to the development of resistance to either drug alone.
Stage-Specific Activity of Pentavalent Antimony against
Leishmania donovani
Axenic Amastigotes
Authors: Ephros Moshe , Bitnun Ari , Shaked Pninit , Waldman Ella , Zilberstein Dan
Published: October 2018

The standard treatment of human visceral leishmaniasis involves the use of pentavalent antimony (SbV) compounds. In recent years increasing numbers of clinical failures of treatment with SbV have been reported, probably due to the development of parasite resistance to this compound. The mode of action and mechanisms of resistance to SbV have not been fully elucidated. In the present study an axenic amastigote culture was used to study the in vitro responses of
Leishmania donovani
to SbV. Susceptibility to both sodium stibogluconate and meglumine antimoniate was found to be stage specific. Amastigotes were 73 to 271 times more susceptible to SbV than were promastigotes. As opposed to SbV, trivalent antimony (SbIII) was similarly toxic to both developmental stages. When promastigotes were transformed to amastigotes, susceptibility to meglumine antimoniate developed after 4 to 5 days, upon the completion of differentiation. In contrast, with transformation from amastigotes to promastigotes, resistance to meglumine antimoniate was acquired rapidly, within 24 h, before the completion of differentiation. The culture of promastigotes at an acidic pH (5.5) or at an elevated temperature (37°C) alone did not lead to the appearance of SbV susceptibility, emphasizing the requirement of both these environmental factors for the development of SbV susceptibility. A previously isolated sodium stibogluconate (Pentostam)-resistant
L. donovani
mutant (Ld1S.20) is also resistant to meglumine antimoniate, indicating cross-resistance to SbV-containing compounds. In contrast, no cross-resistance was found with SbIII, suggesting a mechanism of SbV resistance different from that described in
Leishmania tarentolae
. These data show that
L. donovani
susceptibility to SbV is parasite intrinsic, stage specific, and macrophage independent.
Escherichia coli
ATCC 35218 as a Quality Control Isolate for Susceptibility Testing of
Haemophilus influenzae
with Haemophilus Test Medium
Authors: Butler D. L. , Jakielaszek C. J. , Miller L. A. , Poupard J. A.
Published: October 2018

Current National Committee for Clinical Laboratory Standards (NCCLS) susceptibility guidelines for quality control testing with
Haemophilus influenzae
do not include a β-lactamase-producing strain that could detect the deterioration of the β-lactamase inhibitor components of amoxicillin-clavulanic acid, ampicillin-sulbactam, and piperacillin-tazobactam. The objective of the study was to determine if comparable quality control results for
Escherichia coli
ATCC 35218, a β-lactamase-producing strain, would be produced for the three β-lactam–β-lactamase inhibitor agents with Haemophilus test medium and Mueller-Hinton medium. The criteria used in this study to determine if Haemophilus test medium was acceptable for quality control testing of
E. coli
ATCC 35218 was that 100% of the results obtained with an antimicrobial agent-methodology combination needed to be within the acceptable NCCLS ranges established with Mueller-Hinton medium. The MIC testing results obtained by the broth microdilution and E-test methods with amoxicillin-clavulanic acid and piperacillin-tazobactam were all within the NCCLS ranges; however, the results obtained with ampicillin-sulbactam by both methods were not within the NCCLS ranges. Acceptable results were obtained by the disk diffusion methodology with ampicillin-sulbactam and piperacillin-tazobactam but not with amoxicillin-clavulanic acid. When performing susceptibility testing with
H. influenzae
with the β-lactam–β-lactamase inhibitors, in addition to quality control testing with
H. influenzae
ATCC 49247, testing of
E. coli
ATCC 35218 on Haemophilus test medium is an effective way to monitor the β-lactamase inhibitors in some antimicrobial agent-methodology combinations.
In Vivo Emergence of Multidrug-Resistant Mutants ofPseudomonas aeruginosaOverexpressing the Active Efflux System MexA-MexB-OprM
Authors: Ziha-Zarifi Isabelle , Llanes Catherine , Köhler Thilo , Pechere Jean-Claude , Plesiat Patrick
Published: October 2018

During a 6-month period, 21 pairs ofPseudomonas aeruginosaisolates susceptible (pretherapy) and resistant (posttherapy) to antipseudomonal β-lactam antibiotics were isolated from hospitalized patients. In vivo emergence of β-lactam resistance was associated with the overexpression of AmpC β-lactamase in 10 patients. In the other 11 patients, the posttherapy isolates produced only low, basal levels of β-lactamase and had increased levels of resistance to a variety of non-β-lactam antibiotics (e.g., quinolones, tetracyclines, and trimethoprim) compared with the levels of β-lactamase production and resistance of their pretherapy counterparts. These data suggested the involvement of the MexA-MexB-OprM active efflux system in the multidrug resistance phenotype of the posttherapy strains. Immunoblotting of the outer membrane proteins of these 11 bacterial pairs with a specific polyclonal antibody raised against OprM demonstrated the overexpression of OprM in all the posttherapy isolates. To determine whether mutations inmexR, the regulator gene of themexA-mexB-oprMefflux operon, could account for the overproduction of the efflux system, sequencing experiments were carried out with the 11 bacterial pairs. Eight posttherapy isolates were found to contain insertions or deletions that led to frameshifts in the coding sequences ofmexR. Two resistant strains had point mutations inmexRthat yielded single amino acid changes in the protein MexR, while another strain did not show any mutation inmexRor in the promoter region upstream ofmexR. Introduction of a plasmid-encoded wild-typemexRgene into five posttherapy isolates partially restored the susceptibility of the bacteria to selected antibiotics. These results indicate that in the course of antimicrobial therapy multidrug-resistant active efflux mutants overexpressing the MexA-MexB-OprM system may emerge as a result of mutations in themexRgene.
Activities of Newer Fluoroquinolones against
Streptococcus pneumoniae
Clinical Isolates Including Those with Mutations in the
gyrA
,
parC
, and
parE
Loci
Authors: Jorgensen J. H. , Weigel L. M. , Ferraro M. J. , Swenson J. M. , Tenover F. C.
Published: October 2018

Resistance to fluoroquinolone (FQ) antibiotics in
Streptococcus pneumoniae
has been attributed primarily to specific mutations in the genes for DNA gyrase (
gyrA
and
gyrB
) and topoisomerase IV (
parC
and
parE
). Resistance to some FQs can result from a single mutation in one or more of the genes encoding these essential enzymes. A group of 160 clinical isolates of pneumococci was examined in this study, including 36 ofloxacin-resistant isolates (MICs, ≥8 μg/ml) recovered from patients in North America, France, and Belgium. The susceptibilities of all isolates to clinafloxacin, grepafloxacin, levofloxacin, sparfloxacin, and trovafloxacin were examined by the National Committee for Clinical Laboratory Standards reference broth microdilution and disk diffusion susceptibility testing methods. Among the ofloxacin-resistant strains, 32 of 36 were also categorized as resistant to levofloxacin, 35 were resistant to sparfloxacin, 29 were resistant to grepafloxacin, and 19 were resistant to trovafloxacin. In vitro susceptibility to clinafloxacin appeared to be least affected by resistance to the other FQs. Eight isolates with high- and low-level resistance to the newer FQs were selected for DNA sequence analysis of the quinolone resistance-determining regions (QRDRs) of
gyrA
,
gyrB
,
parC
, and
parE
. The DNA and the inferred amino acid sequences of the resistant strains were compared with the analogous sequences of reference strain
S. pneumoniae
ATCC 49619 and FQ-susceptible laboratory strain R6. Reduced susceptibilities to grepafloxacin and sparfloxacin (MICs, 1 to 2 μg/ml) and trovafloxacin (MICs, 0.5 to 1 μg/ml) were associated with either a mutation in
parC
that led to a single amino acid substitution (Ser-79 to Phe or Tyr) or double mutations that involved the genes for both GyrA (Ser-81 to Phe) and ParE (Asp-435 to Asn). High-level resistance to all of the compounds except clinafloxacin was associated with two or more amino acid substitutions involving both GyrA (Ser-81 to Phe) and ParC (Ser-79 to Phe or Ser-80 to Pro and Asp-83 to Tyr). No mutations were observed in the
gyrB
sequences of resistant strains. These data indicate that mutations in pneumococcal
gyrA
,
parC
, and
parE
genes all contribute to decreased susceptibility to the newer FQs, and genetic analysis of the QRDR of a single gene, either
gyrA
or
parC
, is not predictive of pneumococcal resistance to these agents.
Effects of NorA Inhibitors on In Vitro Antibacterial Activities and Postantibiotic Effects of Levofloxacin, Ciprofloxacin, and Norfloxacin in Genetically Related Strains of
Staphylococcus aureus
Authors: Aeschlimann Jeffrey R. , Dresser Linda D. , Kaatz Glenn W. , Rybak Michael J.
Published: October 2018

NorA is a membrane-associated multidrug efflux protein that can decrease susceptibility to fluoroquinolones in
Staphylococcus aureus
. To determine the effect of NorA inhibition on the pharmacodynamics of fluoroquinolones, we evaluated the activities of levofloxacin, ciprofloxacin, and norfloxacin with and without various NorA inhibitors against three genetically related strains of
S. aureus
(SA 1199, the wild-type; SA 1199B, a NorA hyperproducer with a
grlA
mutation; and SA 1199-3, a strain that inducibly hyperproduces NorA) using susceptibility testing, time-kill curves, and postantibiotic effect (PAE) methods. Levofloxacin had the most potent activity against all three strains and was minimally affected by addition of NorA inhibitors. In contrast, reserpine, omeprazole, and lansoprazole produced 4-fold decreases in ciprofloxacin and norfloxacin MICs and MBCs for SA 1199 and 4- to 16-fold decreases for both SA 1199B and SA 1199-3. In time-kill experiments reserpine, omeprazole, or lansoprazole increased levofloxacin activity against SA 1199-3 alone by 2 log
10
CFU/ml and increased norfloxacin and ciprofloxacin activities against all three strains by 0.5 to 4 log
10
CFU/ml. Reserpine and omeprazole increased norfloxacin PAEs on SA 1199, SA 1199B, and SA 1199-3 from 0.9, 0.6, and 0.2 h to 2.5 to 4.5, 1.1 to 1.3, and 0.4 to 1.1 h, respectively; similar effects were observed with ciprofloxacin. Reserpine and omeprazole increased the levofloxacin PAE only on SA 1199B (from 1.6 to 5.0 and 3.1 h, respectively). In conclusion, the NorA inhibitors dramatically improved the activities of the more hydrophilic fluoroquinolones (norfloxacin and ciprofloxacin). These compounds may restore the activities of these fluoroquinolones against resistant strains of
S. aureus
or may potentially enhance their activities against sensitive strains.
Antimicrobial Resistance of 1,113
Streptococcus pneumoniae
Isolates from Patients with Respiratory Tract Infections in Spain: Results of a 1-Year (1996–1997) Multicenter Surveillance Study
Authors: Baquero Fernando , García-Rodríguez José Angel , García de Lomas Juan , Aguilar Lorenzo ,   The Spanish Surveillance Group for Respiratory Pathogens
Published: October 2018

A nationwide susceptibility surveillance of 1,113
Streptococcus pneumoniae
isolates was carried out and found the following percentages of resistance: cefuroxime, 46%; penicillin, 37%; macrolides, 33%; aminopenicillins, 24%; cefotaxime, 13%; and ceftriaxone, 8%. A significant
(P
< 0.05) seasonality pattern for β-lactam antibiotics was observed. Resistance to macrolides was higher
(P
< 0.05) in middle-ear samples. Higher percentages of resistance to cefuroxime and macrolides were observed among penicillin-intermediate and -resistant strains, whereas high frequencies of resistance to aminopenicillins and expanded-spectrum cephalosporins were observed only among penicillin-resistant strains.
In Vitro Activities of Benflumetol against 158 Senegalese Isolates of
Plasmodium falciparum
in Comparison with Those of Standard Antimalarial Drugs
Authors: Pradines Bruno , Tall Adama , Fusai Thierry , Spiegel Andre , Hienne Remi , Rogier Christophe , Trape Jean Francois , Le Bras Jacques , Parzy Daniel
Published: October 2018

The 50% inhibitory concentration (IC
50
s) of benflumetol (range, 12.5 to 240 nM; mean, 55.1 nM) for 158 Senegalese isolates were evaluated. Ten isolates (6%) showed decreased susceptibility to benflumetol. Benflumetol was slightly more potent against chloroquine-resistant isolates (
P
< 0.025). No correlation or weak correlations in the responses to benflumetol and pyrimethamine, chloroquine, amodiaquine, artemether, quinine, and pyronaridine were observed, and these correlations are insufficient to suggest cross-resistance. Benflumetol may be an important alternative drug for the treatment of chloroquine-resistant malaria.