bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitazoxanide, a Potential Drug for Eradication of
Helicobacter pylori
with No Cross-Resistance to Metronidazole
Authors: Mégraud Francis , Occhialini Alessandra , Rossignol Jean François
Published: October 2018

Nitazoxanide, a thiazolide compound, and its desacetyl derivative, tizoxanide, have antimicrobial properties against anaerobic bacteria, as well as against helminths and protozoa. Because the treatment of
Helicobacter pylori
infection may be jeopardized by metronidazole resistance, nitazoxanide and tizoxanide were tested in vitro against these bacteria. The MICs of these two compounds were determined by agar dilution and were compared to those of metronidazole. Exposure to subinhibitory concentrations of nitazoxanide was also carried out by the method of Szybalski (W. Szybalski and V. Bryson, J. Bacteriol. 64:489–499, 1952). The MICs of nitazoxanide and tizoxanide for 103 strains ranged from 0.25 to 8 μg/ml, with the MIC at which 50% of strains are inhibited (MIC
50
) being 1 μg/ml and the MIC
90
being 4 μg/ml, and no resistant strain was detected, whereas strains resistant to metronidazole were detected. When 10 strains were successively subcultured on medium containing nitazoxanide, no significant change in the MICs of this compound was observed. A pilot study of nitazoxanide for the treatment of
H. pylori
infection was carried out with 86 patients in association with 20 mg of omeprazole. An eradication rate of 83% (95% confidence interval, 64% to 94%) was obtained in a per-protocol analysis in the group receiving 1 g of nitazoxanide orally twice daily, and a few side effects were observed. The failures could not be explained by the selection of resistant strains since the MICs of nitazoxanide were similar for six pairs of isolates (proven to be the same strain by random amplified polymorphic DNA analysis in four cases) cultured before and after the treatment failure. Nitazoxanide exhibits good antimicrobial activity against
H. pylori
without the problem of acquired resistance which is encountered with metronidazole and has been demonstrated to have a satisfactory effect in a dose-ranging pilot study. It is therefore a good candidate to be included in treatment regimens aimed at the eradication of
H. pylori
.
Comparative Efficacy Evaluation of Dicationic Carbazole Compounds, Nitazoxanide, and Paromomycin against
Cryptosporidium parvum
Infections in a Neonatal Mouse Model
Authors: Blagburn Byron L. , Drain Kathryn L. , Land Tracey M. , Kinard Rachel G. , Moore P. Hutton , Lindsay David S. , Patrick Donald A. , Boykin David W. , Tidwell Richard R.
Published: October 2018

The efficacies of dicationic carbazole compounds, nitazoxanide (NTZ), and paromomycin were evaluated against the AUCp1 isolate of
Cryptosporidium parvum
by using a neonatal mouse model. Compounds were solubilized or suspended in deionized water and administered orally by gavage to neonatal mice at a constant dose rate on days 0 to 5 (treatment started on day 0). Dose rates varied for individual carbazole compounds but ranged from 0.65 to 20 mg/kg of body weight. NTZ was tested at 100 and 150 mg/kg, and paromomycin was tested at 50 mg/kg. Efficacies were determined by comparing numbers of oocysts present in treated versus control mice at necropsy examination on day 6. Demonstrable efficacy was observed for several carbazole compounds, based on significant reductions in the numbers of oocysts recovered from treated mice versus control mice. Compounds 1, 7, and 10 (19.0 mg/kg) reduced oocyst passage in treated mice to less than 5% of that in control mice. Treatment with compounds 6, 8, and 9 (17.0 mg/kg) resulted in reductions of oocyst output to less than 10% of that in controls. Although they were not comparable in efficacy to compounds 1, 6, 7, 8, 9, and 10, treatment with other carbazole compounds resulted in statistically significant reductions in oocyst output in treated versus control mice. Compound 1 retained efficacy resulted in reduction of oocyst output to approximately 6% of that in controls when the dose was reduced to 5 mg/kg. Further reductions in the dose rate resulted in considerable reductions in anticryposporidial activity. Likewise, the efficacies of compounds 9 and 10 were reduced substantially when the doses were lowered to one-half the screening dose. Paromomycin yielded excellent activity (reduction of oocyst output to <2% of that in controls) at a dose of 50 mg/kg. NTZ yielded moderate efficacy as powder and injectable formulations administered at 100 mg/kg orally (reduction of oocyst output to 42 and 26% of that in controls, respectively). Oral administration of the injectable formulation of NTZ at a dose of 150 mg/kg resulted in improved efficacy (oocyst output, <5% of that in controls).
Effect of Disruption of a Gene Encoding an Autolysin of
Enterococcus faecalis
OG1RF
Authors: Qin Xiang , Singh Kavindra V. , Xu Yi , Weinstock George M. , Murray Barbara E.
Published: October 2018

A mutant (TX5127) of
Enterococcus faecalis
OG1RF was generated by disruption mutagenesis of a previously described autolysin gene. TX5127 formed longer chains (2 to 10 cells per chain) than wild-type OG1RF (mainly single cells) during growth in broth even though it had a growth rate similar to that of the parental strain as measured by turbidity and cell count. Autolysin activity, as defined by the ability to lyse heat-killed
Micrococcus lysodeikticus
cells, was absent in TX5127, while this activity was easily detectable in OG1RF. However, disruption of this autolysin gene did not block the ability of TX5127 to hydrolyze
E. faecalis
cell walls compared to that of OG1RF. The autolysis rate of cells of TX5127 in 10 mM sodium phosphate buffer (pH 6.8) was slower than that of wild-type OG1RF. TX5127 also showed a decreased rate of lysis in the presence of penicillin, as measured by changes in the turbidity of the culture during 24 h of incubation at 37°C and a slightly decreased effect of penicillin as measured by time-kill curves. The virulence of TX5127 was similar to that of OG1RF in the mouse peritonitis model, indicating that the autolysin of
E. faecalis
is not important for infection in this model.
Diversity of Structures Carrying the High-Level Gentamicin Resistance Gene
(aac6-aph2)
in
Enterococcus faecalis
Strains Isolated in France
Authors: Casetta Anne , Hoï Annie Buu , de Cespédès Gilda , Horaud Thea
Published: October 2018

Of 24 high-level gentamicin-resistant clinical isolates of
Enterococcus faecalis
, 20 carried gentamicin resistance (Gm
r
) plasmids. The plasmids ranged from 65.0 to 80.0 kb in size. Three of these plasmids were nonconjugative, and 17 transferred by conjugation to an
E. faecalis
recipient at low frequency (10
−5
to 10
−6
transconjugants per donor). The remaining four strains had a nonconjugative chromosomal Gm
r
determinant. On the basis of restriction enzyme and DNA-DNA hybridization profiles, Tn
4001
-like α elements were located on the chromosome and three types of Tn
4001
-truncated structures, I, II, and III, were found to be carried by the Gm
r
plasmids. Structure I lacked IS
256
in the right-hand flanking extremity of Tn
4001
. Structure II was the same as structure I except that it also had a partial deletion of IS
256
in the left-hand flanking extremity of Tn
4001
. Structure III lacked both the right- and left-hand flanking extremities of Tn
4001
. One of the wild-type strains carried the Gm
r
determinant both on the chromosome, as a Tn
4001
-like α element, and on a conjugative plasmid, as a Tn
4001
-truncated type I structure.
Antifungal Efficacy, Safety, and Single-Dose Pharmacokinetics of LY303366, a Novel Echinocandin B, in Experimental Pulmonary Aspergillosis in Persistently Neutropenic Rabbits
Authors: Petraitis Vidmantas , Petraitiene Ruta , Groll Andreas H. , Bell Aaron , Callender Diana P. , Sein Tin , Schaufele Robert L. , McMillian Carl L. , Bacher John , Walsh Thomas J.
Published: October 2018

LY303366 is a novel semisynthetic derivative of echinocandin B and a potent inhibitor of fungal (1,3)-β-
d
-glucan synthase. The antifungal efficacy and safety of LY303366 were investigated in treatment and prophylaxis of primary pulmonary aspergillosis due to
Aspergillus fumigatus
in persistently neutropenic rabbits. Treatment study groups were either not treated (controls) or treated with amphotericin B (AmB) at 1 mg/kg of body weight per day or with LY303366 at 1, 5, 10, and 20 mg/kg/day. In rabbits treated with LY303366, there was a significant improvement in survival and a reduction in organism-mediated pulmonary injury measured by the number of infarcts, total lung weight, and ultrafast computerized tomography scan pulmonary lesion score. Rabbits receiving prophylactic LY303366 also demonstrated significant improvement in survival and reduction in organism-mediated pulmonary injury. AmB and LY303366 had comparable therapeutic efficacies by all parameters with the exception of reduction in tissue burden of
A. fumigatus
, where AmB was superior to LY303366. LY303366 demonstrated a dose-dependent effect on hyphal injury with progressive truncation, swelling, and vacuolization. LY303366 administered in single doses of 1, 5, 10, and 20 mg/kg demonstrated dose-proportional increases in the maximum concentration of drug in plasma and the area under the concentration-time curve from 0 to 72 h with no changes in plasma drug clearance. The 1-mg/kg dosage maintained plasma drug levels above the MIC for 18 h, and dosages of ≥5 mg/kg maintained plasma drug levels above the MIC for the entire 24-h dosing interval. There was no significant elevation of the concentrations of hepatic transaminases or creatinine in serum in LY303366-treated rabbits. In summary, LY303366 improved survival and decreased pulmonary injury with no apparent toxicity in the treatment and prevention of invasive pulmonary aspergillosis in persistently neutropenic rabbits.
Specific Activities of Dolastatin 10 and Peptide Derivatives against
Cryptococcus neoformans
Authors: Pettit Robin K. , Pettit George R. , Hazen Kevin C.
Published: October 2018

The biosynthetic peptide dolastatin 10 is currently in phase I and II cancer clinical trials. We evaluated the antifungal spectrum of dolastatin 10 and four structural modifications. In broth macrodilution assays, the peptides were fungicidal for American Type Culture Collection strains and clinical isolates (including fluconazole-resistant strains) of
Cryptococcus neoformans
but no other yeasts or filamentous fungi examined. Specificity for
C. neoformans
was also demonstrated in the solid-phase disk diffusion assay, and fungicidal activity was confirmed in time-kill experiments. For a methyl ester modification, the MICs at which 50 and 90% of 19 clinical isolates were inhibited (MIC
50
and MIC
90
, respectively) were 0.195 and 0.39 μg/ml, respectively. The MFC
50
(50% minimum fungicidal concentration) for this peptide was 0.39 μg/ml, and the MFC
90
was 0.78 μg/ml. MICs and MFCs were identical or lower in the presence of human serum but increased with lowered pH. These peptides should be pursued as potential chemotherapeutics for
C. neoformans
, a leading cause of infection and mortality in immunocompromised patients.
Purification and Characterization of Virginiamycin M
1
Reductase from
Streptomyces virginiae
Authors: Suzuki Naoyoshi , Lee Chang-Kwon , Nihira Takuya , Yamada Yasuhiro
Published: October 2018

Virginiamycin M
1
(VM
1
), produced by
Streptomyces virginiae
, is a polyunsaturated macrocyclic lactone antibiotic belonging to the virginiamycin A group.
S. virginiae
possesses an activity which stereospecifically reduces a 16-carbonyl group of VM
1
, resulting in antibiotically inactive 16
R
-dihydroVM
1
. The corresponding VM
1
reductase was purified to homogeneity from crude extracts of
S. virginiae
in five steps, with 5,650-fold purification and 23% overall yield. The N-terminal amino acid sequence was determined to be MAIKLVIA. The purified enzyme showed an apparent
M
r
of 73,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and an
M
r
of 280,000 by native molecular sieve high-performance liquid chromatography, indicating the tetrameric nature of the native enzyme. NADPH served as a coenzyme for the reduction, with a

K
m

value of 0.13 mM, but NADH did not support the reaction, even at a concentration of 5 mM, indicating the NADPH-specific nature of the enzyme. The

K
m

for VM
1
was determined to be 1.5 mM in the presence of 2 mM NADPH. In the reverse reaction, only 16
R
-dihydroVM
1
, not the 16
S
-epimer, served as a substrate, with a less than 0.1% overall reaction rate compared to that of the forward reaction, confirming that the VM
1
reductase participates solely in VM
1
inactivation in vivo.
Pulsed-Exposure and Postantibiotic Leukocyte Enhancement Effects of Amikacin, Clarithromycin, Clofazimine, and Rifampin against Intracellular
Mycobacterium avium
Authors: Horgen Lionel , Jerome Arnaud , Rastogi Nalin
Published: October 2018

We investigated the postantibiotic effects (PAEs) of four agents against
Mycobacterium avium
in a human macrophage model under two different experimental conditions. For postantibiotic leukocyte enhancement (PALE), bacteria were exposed to antibiotics prior to their phagocytosis, whereas for pulsed exposure (PE), antibiotics were added after phagocytosis. In both cases, the drugs were used at their peak concentrations in serum (
C
max
) for 2 h. The results showed two different patterns: one for the drug for which results under PE and PALE test conditions did not significantly differ (amikacin) and one for drugs for which PAE values were significantly higher under PE test conditions (clarithromycin, clofazimine, and rifampin). These data suggest that even a brief exposure of
M. avium
to peak concentrations of certain drugs in serum may result in prolonged and persistent suppression of bacterial growth inside human macrophages.
Comparison of Ceftriaxone, Amikacin, and Ciprofloxacin in Treatment of Experimental
Yersinia enterocolitica
O9 Infection in Mice
Authors: Jiménez-Valera Maria , Gonzalez-Torres Concepción , Moreno Encarnación , Ruiz-Bravo Alfonso
Published: October 2018

Ceftriaxone and ciprofloxacin were effective in the treatment of
Yersinia enterocolitica
O9 intestinal infection in mice. Amikacin was less effective. The impact of these drugs on indigenous bacteria from the intestinal microbiota was studied.
Multiple Molecular Mechanisms Contribute to a Stepwise Development of Fluconazole Resistance in Clinical
Candida albicans
Strains
Authors: Franz Renate , Kelly Steven L. , Lamb David C. , Kelly Diane E. , Ruhnke Markus , Morschhäuser Joachim
Published: October 2018

From each of two AIDS patients with oropharyngeal candidiasis, five
Candida albicans
isolates from recurrent episodes of infection which became gradually resistant against fluconazole during antimycotic treatment were analyzed for molecular changes responsible for drug resistance. In both patients, a single
C. albicans
strain was responsible for the recurrent infections, but the
CARE-2
fingerprint pattern of the isolates exhibited minor genetic alterations, indicating that microevolution of the strains took place during fluconazole therapy. In the isolates from patient 1, enhanced mRNA levels of the
MDR1
gene, encoding a multiple drug resistance protein from the superfamily of major facilitators, and constitutive high expression of the
ERG11
gene, coding for the drug target enzyme sterol 14α-demethylase, correlated with a stepwise development of fluconazole resistance. The resistant strains exhibited reduced accumulation of fluconazole and, for the last in the series, a slight increase in drug needed to inhibit sterol 14α-demethylation in vitro. In the isolates from patient 2, increased
MDR1
mRNA levels and the change from heterozygosity to homozygosity for a mutant form of the
ERG11
gene correlated with continuously decreased drug susceptibility. In this series, reduced drug accumulation and increased resistance in the target enzyme activity, sterol 14α-demethylase, were observed. These results demonstrate that different molecular mechanisms contribute to a gradual development of fluconazole resistance in
C. albicans.
Inhibition of Duck Hepatitis B Virus Replication by 9-(2-Phosphonylmethoxyethyl)adenine, an Acyclic Phosphonate Nucleoside Analogue
Authors: Nicoll A. J. , Colledge D. L. , Toole J. J. , Angus P. W. , Smallwood R. A. , Locarnini S. A.
Published: October 2018

The use of regimens that use nucleoside analogues for the treatment of chronic hepatitis B virus infection is often limited because of their high relapse rates. This is thought to be due to the persistence of virus in nonhepatocyte reservoirs and/or the viral covalently closed circular (CCC) DNA species in the nucleus of infected hepatocytes. We have evaluated the novel nucleoside analogue 9-(2-phosphonylmethoxyethyl)adenine (PMEA) in the duck model of hepatitis B. Eight Pekin-Aylesbury ducks congenitally infected with the duck hepatitis B virus (DHBV) were treated with PMEA at a dosage of 15 mg/kg of body weight/day via the intraperitoneal route for 4 weeks. At the end of the treatment period, four animals were killed and the remainder were monitored for a further 4-week drug-free period before analysis. The results were compared with those for eight age-matched, untreated controls. The levels of viremia, the total intrahepatic DHBV load, and CCC DNA, viral RNA, and protein levels were measured by Southern hybridization, Northern hybridization, and immunoblotting of the appropriate specimen, respectively. Viral proteins and DNA were also measured by immunohistochemistry (IHC) and in situ hybridization (ISH) of sections of liver and pancreatic tissue. PMEA treatment reduced the viremia to undetectable levels, while the total viral DNA load in the liver was reduced by 95% compared to the control level. Viral RNA and protein levels decreased by approximately 30%. ISH and IHC confirmed the PMEA-related intrahepatic changes and established that the amount of virus in bile duct epithelial cells (BDEC) was reduced by 70% during therapy. During the follow-up period all parameters of active virological replication returned to those for the age-matched controls. PMEA had no significant effect upon the number of virus-infected islet or acinar cells in the pancreas. PMEA at a dosage of 15 mg/kg/day has potent activity against DHBV found within hepatocytes and BDEC and inhibits DHBV replication in BDEC.
Inhibition of Human Hepatitis B Virus Replication by AT-61, a Phenylpropenamide Derivative, Alone and in Combination with (−)β-
l
-2′,3′-Dideoxy-3′-Thiacytidine
Authors: King Robert W. , Ladner Stephanie K. , Miller Thomas J. , Zaifert Katie , Perni Robert B. , Conway Sameul C. , Otto Michael J.
Published: October 2018

AT-61, a member of a novel class of phenylpropenamide derivatives, was found to be a highly selective and potent inhibitor of human hepatitis B virus (HBV) replication in four different human hepatoblastoma cell lines which support the replication of HBV (i.e., HepAD38, HepAD79, 2.2.15, and transiently transfected HepG2 cells). This compound was equally effective at inhibiting both the formation of intracellular immature core particles and the release of extracellular virions, with 50% effective concentrations ranging from 0.6 to 5.7 μM. AT-61 (27 μM) was able to reduce the amount of HBV covalently closed circular DNA found in the nuclei of HepAD38 cells by >99%. AT-61 at concentrations of >27 μM had little effect on the amount of viral RNA found within the cytoplasms of induced HepAD38 cells but reduced the number of immature virions which contained pregenomic RNA by >99%. The potency of AT-61 was not affected by one of the mutations responsible for (−)-β-
l
-2′,3′-dideoxy-3′ thiacytidine (3TC) resistance in HBV, and AT-61 acted synergistic with 3TC to inhibit HBV replication. AT-61 (81 μM) was not cytotoxic or antiproliferative to several cell lines and had no antiviral effect on woodchuck or duck HBV, human immunodeficiency virus type 1, herpes simplex virus type 1, vesicular stomatitis virus, or Newcastle disease virus. Therefore, we concluded that the antiviral activity of AT-61 is specific for HBV replication and most likely occurs at one of the steps between the synthesis of viral RNA and the packaging of pregenomic RNA into immature core particles.
In Vitro Susceptibilities of
Candida
Bloodstream Isolates to the New Triazole Antifungal Agents BMS-207147, Sch 56592, and Voriconazole
Authors: Pfaller M. A. , Messer S. A. , Hollis R. J. , Jones R. N. , Doern G. V. , Brandt M. E. , Hajjeh R. A.
Published: October 2018

BMS-207147, Sch 56592, and voriconazole are three new investigational triazoles with broad-spectrum antifungal activity. The in vitro activities of these three agents were compared with those of itraconazole and fluconazole against 1,300 bloodstream isolates of
Candida
species obtained from over 50 different medical centers in the United States. The MICs of all of the antifungal drugs were determined by broth microdilution tests performed according to the National Committee for Clinical Laboratory Standards method using RPMI 1640 as a test medium. BMS-207147, Sch 56592, and voriconazole were all quite active against all
Candida
sp. isolates (MICs for 90% of the isolates tested [MIC
90
s], 0.5, 1.0, and 0.5 μg/ml, respectively).
Candida albicans
was the most susceptible species (MIC
90
s, 0.03, 0.06, and 0.06 μg/ml, respectively), and
C. glabrata
was the least susceptible (MIC
90
s, 4.0, 4.0, and 2.0 μg/ml, respectively). BMS-207147, Sch 56592, and voriconazole were all more active than itraconazole and fluconazole against
C. albicans
,
C. parapsilosis
,
C. tropicalis
, and
C. krusei
. There existed a clear rank order of in vitro activity of the five azoles examined in this study when they were tested versus
C. glabrata
: voriconazole > BMS-207147 = Sch 56592 = itraconazole > fluconazole (MIC
90
s, 2.0, 4.0, 4.0, 4.0, and 64 μg/ml, respectively). For isolates of
Candida
spp. with decreased susceptibility to both itraconazole and fluconazole, the MICs of BMS-207147, Sch 56592, and voriconazole were also elevated. These results suggest that BMS-207147, Sch 56592, and voriconazole all possess promising antifungal activity and that further in vitro and in vivo investigations are warranted to establish the clinical value of this improved potency.
Induction of Resistance to Azole Drugs in
Trypanosoma cruzi
Authors: Buckner Frederick S. , Wilson Aaron J. , White Theodore C. , Van Voorhis Wesley C.
Published: October 2018

Trypanosoma cruzi
is the protozoan parasite that causes Chagas’ disease, a frequently fatal illness affecting the heart and gastrointestinal systems. An estimated 16 million to 18 million people in Latin America and 50,000 to 100,000 people in the United States are infected with this pathogen. Treatment options for
T. cruzi
infections are suboptimal due to the toxicities and limited effectiveness of the available drugs. Azole antimicrobial agents have been discovered to have antitrypanosomal activity by inhibition of ergosterol synthesis. The triazole itraconazole was recently shown to produce a parasitologic cure rate of 53% in chronically infected patients (W. Apt et al., Am. J. Trop. Med. Hyg. 59:133–138, 1998), a result which may lead to more use of this family of drugs for the treatment of
T. cruzi
infections. In the experiments reported on here, resistance to azoles was induced in vitro by serial passage of mammalian-stage parasites in the presence of fluconazole for 4 months. These parasites were cross resistant to the other azoles, ketoconazole, miconazole, and itraconazole. They remained susceptible to benznidazole and amphotericin B. The azole-resistant phenotype was stable for more than 2 months of in vitro serial passage without fluconazole. In addition, the parasites resisted treatment in mice receiving ketoconazole. The rapid development of azole resistance in
T. cruzi
in vitro suggests that resistance to azole drugs has the potential to occur in patients and may pose an impediment to the progress being made in the treatment of
T. cruzi
infection.
Ceftazidime-Resistant
Enterobacteriaceae
Isolates from Three Polish Hospitals: Identification of Three Novel TEM- and SHV-5-Type Extended-Spectrum β-Lactamases
Authors: Gniadkowski Marek , Schneider Ines , Jungwirth Renate , Hryniewicz Waleria , Bauernfeind Adolf
Published: October 2018

Twelve ceftazidime-resistant isolates of the family
Enterobacteriaceae
(11
Klebsiella pneumoniae
isolates and 1
Escherichia coli
isolate) were collected in 1995 from three Polish hospitals located in different cities. All were identified as producers of extended-spectrum β-lactamases (ESBLs). Detailed analysis of their β-lactamase contents revealed that six of them expressed SHV-5-like ESBLs. The remaining six were found to produce three different TEM enzymes, each characterized by a pI value of 6.0 and specified by new combinations of amino acid substitutions. The amino acid substitutions compared to the TEM-1 β-lactamase sequence were Gly238Ser, Glu240Lys, and Thr265Met for TEM-47; Leu21Phe, Gly238Ser, Glu240Lys, and Thr265Met for TEM-48; and Leu21Phe, Gly238Ser, Glu240Lys, Thr265Met, and Ser268Gly for TEM-49. The new TEM β-lactamases, TEM-47, TEM-48, and TEM-49, belong to a subfamily of TEM-2-related enzymes. Genes coding for TEM-47 and TEM-49 could have originated from the TEM-48-encoding sequence by various single genetic events. The new TEM derivatives probably document the already advanced microevolution of ESBLs ongoing in Polish hospitals, in a majority of which no monitoring of ESBL producers was performed before 1996.
Anti-Human Immunodeficiency Virus Activity and Cellular Metabolism of a Potential Prodrug of the Acyclic Nucleoside Phosphonate 9-
R
-(2-Phosphonomethoxypropyl)adenine (PMPA), Bis(isopropyloxymethylcarbonyl)PMPA
Authors: Robbins Brian L. , Srinivas Ranga V. , Kim Choung , Bischofberger Norbert , Fridland Arnold
Published: October 2018

Bis(isopropyloxymethylcarbonyl) 9-
R
-(2-phosphonomethoxypropyl)adenine [bis(POC)PMPA] has been identified as a novel prodrug of PMPA. The anti-human immunodeficiency virus activity of bis(POC)PMPA was >100-fold greater than that of PMPA in both an established T-cell line and primary peripheral blood lymphocytes. This improved efficacy was shown to be due to a rapid intracellular uptake of the prodrug resulting in an increased intracellular accumulation of PMPA diphosphate (PMPApp), the pharmacologically active metabolite. PMPApp levels in bis(POC)PMPA-treated cells exceeded by >1,000-fold the levels seen in cells treated with unmodified PMPA in both resting and activated peripheral blood lymphocytes. Significant differences in the intracellular catabolism of PMPA metabolites were noted between the resting and activated lymphocytes. The half-life for the disappearance of PMPApp, derived from either bis(POC)PMPA or PMPA, was 12 to 15 h in the activated lymphocytes and 33 to 50 h in the resting lymphocytes. This long persistence of PMPApp, particularly in resting lymphocytes, may be unique to the nucleoside phosphonate analogs and indicates that effective levels of the active metabolite can be achieved and maintained with relatively infrequent administration of the parent drug.
Tolerance and Pharmacokinetic Interactions of Rifabutin and Clarithromycin in Human Immunodeficiency Virus-Infected Volunteers
Authors: Hafner Richard , Bethel James , Power Maureen , Landry Bernard , Banach Mary , Mole Larry , Standiford Harold C. , Follansbee Stephen , Kumar Princy , Raasch Ralph , Cohn David , Mushatt David , Drusano George
Published: October 2018

This study evaluated the tolerance and potential pharmacokinetic interactions between clarithromycin (500 mg every 12 h) and rifabutin (300 mg daily) in clinically stable human immunodeficiency virus-infected volunteers with CD4 counts of <200 cells/mm
3
. Thirty-four subjects were randomized equally to either regimen A or regimen B. On days 1 to 14, subjects assigned to regimen A received clarithromycin and subjects assigned to regimen B received rifabutin, and then both groups received both drugs on days 15 to 42. Of the 14 regimen A and the 15 regimen B subjects who started combination therapy, 1 subject in each group prematurely discontinued therapy due to toxicity, but 19 of 29 subjects reported nausea, vomiting, and/or diarrhea. Pharmacokinetic analysis included data for 11 regimen A and 14 regimen B subjects. Steady-state pharmacokinetic parameters for single-agent therapy (day 14) and combination therapy (day 42) were compared. Regimen A resulted in a mean decrease of 44% (
P
= 0.003) in the clarithromycin area under the plasma concentration-time curve (AUC), while there was a mean increase of 57% (
P
= 0.004) in the AUC of the clarithromycin metabolite 14-OH-clarithromycin. Regimen B resulted in a mean increase of 99% (
P
= 0.001) in the rifabutin AUC and a mean increase of 375% (
P
< 0.001) in the AUC of the rifabutin metabolite 25-
O
-desacetyl-rifabutin. The usefulness of this combination for prophylaxis of
Mycobacterium avium
infections is limited by frequent gastrointestinal adverse events. Coadministration of clarithromycin and rifabutin results in significant bidirectional pharmacokinetic interactions. The resulting increase in rifabutin levels may explain the increased frequency of uveitis observed with concomitant use of these drugs.
Short- and Long-Term Efficacy of Hexadecylphosphocholine against EstablishedLeishmania infantumInfection in BALB/c Mice
Authors: Le Fichoux Yves , Rousseau Déborah , Ferrua Bernard , Ruette Sandrine , Lelièvre Alain , Grousson Dominique , Kubar Joanna
Published: October 2018

In the immunocompetent host, visceral leishmaniasis (VL) is a fatal disease if untreated. In immunosuppressed patients, VL is an opportunistic infection for which there is no effective treatment for relapses. Here we report on the long-term activity of orally administered hexadecylphosphocholine (HDPC) against establishedLeishmania infantuminfection in BALB/c mice. HDPC is a synthetic phospholipid with antiproliferative properties that has been extensively studied for its cancerostatic activity. Its short-term leishmanicidal effects in mice recently infected with viscerotropicLeishmaniaspecies have been previously reported. First, we show that 5 days of oral therapy with HDPC (20 mg/kg of body weight/day) led to amastigote suppression in the liver and the spleen of 94 and 78%, respectively (versus 85 and 55% suppression by meglumine antimonate in the liver and spleen, respectively), in mice infected 6 weeks before treatment and examined 3 days after the end of treatment. These results demonstrate the short-term efficacy of HDPC against an establishedLeishmaniainfection. Next, the long-term efficacy of HDPC was examined. In HDPC-treated mice both the hepatic and splenic amastigote loads were significantly reduced (at least 89%) 10, 31, and 52 days after the end of the treatment. In the treated mice, the increase of the splenic load was significantly slower than that in the untreated mice, demonstrating that the HDPC-exerted inhibition ofLeishmaniagrowth persisted for at least 7 to 8 weeks. Orally administered HDPC—the safe doses and side effects of which are at least partially known—appears to be a promising candidate for the treatment of VL.
The Antibiotic Micrococcin Is a Potent Inhibitor of Growth and Protein Synthesis in the Malaria Parasite
Authors: Rogers M. John , Cundliffe Eric , McCutchan Thomas F.
Published: October 2018

The antibiotic micrococcin is a potent growth inhibitor of the human malaria parasite
Plasmodium falciparum
, with a 50% inhibitory concentration of 35 nM. This is comparable to or less than the corresponding levels of commonly used antimalarial drugs. Micrococcin, like thiostrepton, putatively targets protein synthesis in the plastid-like organelle of the parasite.
Analysis of Diversity of Mutations in the
mecI
Gene and
mecA
Promoter/Operator Region of Methicillin-Resistant
Staphylococcus aureus
and
Staphylococcus epidermidis
Authors: Kobayashi Nobumichi , Taniguchi Koki , Urasawa Shozo
Published: October 2018

Genomic diversity of mutation in the
mecI
gene or
mecA
promoter/operator region was analyzed for clinical isolates of methicillin-resistant
Staphylococcus aureus
(MRSA) and
Staphylococcus epidermidis
(MRSE). In most MRSA strains, a single base substitution was detected in either the
mecI
(three different positions) or the
mecA
promoter (two different positions), while a 28-base deletion in
mecI
was found in one strain. In contrast, no mutation was detected in these gene sequences of MRSE strains.
Antiproliferative and Apoptotic Activities of Ketonucleosides and Keto-C-Glycosides against Non-Small-Cell Lung Cancer Cells with Intrinsic Drug Resistance
Authors: Paterson Jesse , Uriel Clara , Egron Marie-Jose , Herscovici Jean , Antonakis Kostas , Alaoui-Jamali Moulay A.
Published: October 2018

We compared the biological activity of a new group of keto-C-glycosides to that of a narrow spectrum of unsaturated ketonucleosides in a panel of non-small-cell lung cancer (NSCLC) cells with various levels of intrinsic resistance to standard chemotherapy drugs. Unlike cisplatin, etoposide, adriamycin, or taxol, for which a significant difference in the cytotoxic effect was observed between sensitive cell lines (H460, H125, and MGH4) and drug-resistant cell lines (H661, MGH7, and FADU), nucleoside analogs were equally cytotoxic in NSCLC cell lines, with compound 92 being 10-fold more active than compound 43, 44, 81, or 161, while compound 3 was the least active. Apoptotic measurements with flow cytometric analysis of terminal uridine deoxynucleotide nick end-labeled cells revealed that the cytotoxic activity of these nucleosides correlated with their potency to induce apoptosis. Compound 92 triggered death in cells with wild-type p53, mutated p53, or p53 gene deletion. Our findings suggest that keto-C-glycosides may be promising alternative anticancer agents which merit further studies in in vivo cancer models refractory to standard chemotherapy drugs.
Discriminatory Detection of Inhibitor-Resistant β-Lactamases in
Escherichia coli
by Single-Strand Conformation Polymorphism-PCR
Authors: Speldooren Valérie , Heym Beate , Labia Roger , Nicolas-Chanoine Marie-Hélène
Published: October 2018

Plasmid-mediated mechanisms, comprising TEM hyperproduction, TEM derivative production, and OXA production, lead to amoxicillin-clavulanic acid resistance in enterobacteria. The ability of the single-strand conformation polymorphism (SSCP)-PCR method to differentiate the genes encoding inhibitor-resistant β-lactamases was evaluated with three
bla
TEM
primer pairs. The
bla
TEM
genes, which were known to be different on the basis of their nucleotide sequences (
bla
TEM-1A
,
bla
TEM-1B
,
bla
TEM-2
,
bla
TEM-30
,
bla
TEM-32
, and
bla
TEM-35
), were identified as different by their electrophoretic mobilities. The
bla
TEM-33
,
bla
TEM-34
,
bla
TEM-36
,
bla
TEM-37
,
bla
TEM-38
, and
bla
TEM-39
genes, whose sequence differences have been established by oligotyping, displayed different SSCP profiles for different fragments, suggesting genetic differences in addition to those defined by oligotyping. Confirmed by sequencing, these additional genetic events concerned silent mutations at certain positions and, notably, a G→T transversion at position 1 of the −10 consensus sequence in
bla
TEM-34
,
bla
TEM-36
,
bla
TEM-37
, and
bla
TEM-39
. Applied to eight clinical isolates of
Escherichia coli
resistant to amoxicillin-clavulanic acid, the SSCP method detected TEM-1 in three strains and TEM-30, TEM-32, and TEM-35 in three other strains, respectively. A novel TEM derivative (TEM-58) was detected in another strain, and the deduced amino acid sequence showed two substitutions: Arg244Ser, which is known to confer amoxicillin-clavulanic acid resistance in TEM-30, and Val261Ile, which has not been described previously. The eighth strain produced an OXA β-lactamase. Given the discriminatory power and the applicability of SSCP-PCR, this method can be proposed as a means of following the evolution of the frequencies of the different inhibitor-resistant β-lactamases.
Activity of Voriconazole, a New Triazole, Combined with Neutrophils or Monocytes against
Candida albicans
: Effect of Granulocyte Colony-Stimulating Factor and Granulocyte-Macrophage Colony-Stimulating Factor
Authors: Vora Shefali , Purimetla Nayanatara , Brummer Elmer , Stevens David A.
Published: October 2018

The antifungal activity of voriconazole (VCZ) was tested against
Candida albicans
in the absence or presence of polymorphonuclear neutrophils (PMN) or monocytes. In some experiments, VCZ was compared to fluconazole (FCZ). On a weight basis, VCZ was 10-fold more efficacious than FCZ against
C. albicans
Sh27. Against an FCZ-resistant isolate, VCZ at 1 μg/ml produced the same fungistasis as FCZ at 20 μg/ml. VCZ at 0.1 μg/ml collaborated with PMN for enhanced killing to the same extent as FCZ at 1.0 μg/ml. Granulocyte-colony-stimulating factor (G-CSF) enhanced the candidacidal activity of PMN, and it increased the collaboration of PMN with VCZ for killing. Granulocyte-macrophage (GM)-CSF also significantly enhanced both the killing by PMN and the collaboration of PMN with VCZ for killing. VCZ collaborated with monocytes for enhanced killing of
C. albicans
Sh27, and GM-CSF increased this collaboration. Taken together, these data show that VCZ is more potent than FCZ against
C. albicans
isolates, alone and in collaboration with PMN or monocytes for enhanced killing. In addition, G-CSF- or GM-CSF-activated PMN and monocytes have enhanced collaboration with VCZ compared to that of unstimulated phagocytes with VCZ.
Effect of Grapefruit Juice on Clarithromycin Pharmacokinetics
Authors: Cheng Kit L. , Nafziger Anne N. , Peloquin Charles A. , Amsden Guy W.
Published: October 2018

To investigate whether grapefruit juice inhibits the metabolism of clarithromycin, 12 healthy subjects were given water or grapefruit juice before and after a clarithromycin dose of 500 mg in a randomized crossover study. Administration of grapefruit juice increased the time to peak concentration of both clarithromycin (82 ± 35 versus 148 ± 83 min;
P
= 0.02) and 14-hydroxyclarithromycin (84 ± 38 min versus 173 ± 85;
P
= 0.01) but did not affect other pharmacokinetic parameters.
Comparative In Vitro Killing Activities of Meropenem, Imipenem, Ceftriaxone, and Ceftriaxone plus Vancomycin at Clinically Achievable Cerebrospinal Fluid Concentrations against Penicillin-Resistant
Streptococcus pneumoniae
Isolates from Children with Meningitis
Authors: Fitoussi Frederic , Doit Catherine , Benali Karim , Bonacorsi Stephane , Geslin Pierre , Bingen Edouard
Published: October 2018

The activities of meropenem, imipenem, ceftriaxone, and vancomycin were evaluated against 80 penicillin-susceptible and -resistant
Streptococcus pneumoniae
strains. Meropenem, imipenem, ceftriaxone, and vancomycin MICs at which 90% of the isolates are inhibited were 0.5, 0.25, 1, and 0.25 μg/ml, respectively. Against penicillin-resistant strains, the best killing activity at cerebrospinal fluid concentrations was obtained with imipenem and ceftriaxone-vancomycin. However, while the killing activity of imipenem was significantly greater than that of meropenem, no significant difference was observed between the activities of meropenem and ceftriaxone-vancomycin.
Antipneumococcal Activities of a Ketolide (HMR 3647), a Streptogramin (Quinupristin-Dalfopristin), a Macrolide (Erythromycin), and a Lincosamide (Clindamycin)
Authors: Barry A. L. , Fuchs P. C. , Brown S. D.
Published: October 2018

Four different compounds belonging to the macrolide-lincosamide-streptogramin B (MLS
b
) class of antimicrobial agents were tested against 611
Streptococcus pneumoniae
strains. The ketolide (HMR 3647, previously RU66647) and the streptogramin (quinupristin-dalfopristin) were both active against pneumococci with high-level MLS
b
resistance (clindamycin-resistant strains) as well as those with low-level macrolide resistance (clindamycin-susceptible strains).
In Vitro and In Vivo Antidermatophyte Activities of NND-502, a Novel Optically Active Imidazole Antimycotic Agent
Authors: Niwano Yoshimi , Kuzuhara Naoki , Kodama Hiroki , Yoshida Masanori , Miyazaki Tsuneo , Yamaguchi Hideyo
Published: October 2018

In vitro and in vivo antidermatophyte activities of NND-502, a new imidazole antimycotic agent, were compared with those of two existing antifungal agents, lanoconazole and terbinafine. NND-502 exhibited strong in vitro antifungal activity against
Trichophyton
spp.; its MIC was 1 to 4 times lower than that of lanoconazole or terbinafine. In an in vivo study with a guinea pig model of tinea pedis, 7-day topical treatment with a 0.5% solution of NND-502 (dissolved in polyethylene glycol 400) was more effective than that with a 0.5% solution of either lanoconazole or terbinafine for eradicating fungi from the infected feet. When the duration of treatment was shortened to 3 days, a topical 1% solution of NND-502 achieved a complete mycological cure, while topical 1% solutions of lanoconazole and terbinafine did not.
In Vitro Antimicrobial Activity of MSI-78, a Magainin Analog
Authors: Fuchs Peter C. , Barry Arthur L. , Brown Steven D.
Published: October 2018

MSI-78 is a cationic peptide with broad-spectrum antimicrobial activity and is being developed as a topical agent. We compared the in vitro activity of MSI-78 with those of ofloxacin and other antibiotics against fresh clinical isolates. Based on MIC distribution statistics, strains for which the MSI-78 MIC was ≤64 μg/ml were assumed to be susceptible for purposes of this report. Of 411 aerobic isolates tested, 91% were susceptible to MSI-78, compared to 91% for ofloxacin and 92% for ciprofloxacin. Only enterococci consistently required ≥64 μg of MSI-78/ml for inhibition. MSI-78 demonstrated bactericidal activity equivalent to that of ofloxacin. Of 61 anaerobes, 97% were susceptible to MSI-78. Of 10 isolates of
Candida albicans
, 3 were inhibited by MSI-78 at 24 h. Further studies of this compound appear to be warranted.
Characterization of
grlA
,
grlB
,
gyrA
, and
gyrB
Mutations in 116 Unrelated Isolates of
Staphylococcus aureus
and Effects of Mutations on Ciprofloxacin MIC
Authors: Schmitz Franz-Josef , Jones Mark E. , Hofmann Basia , Hansen Birgit , Scheuring Sibylle , Lückefahr Marc , Fluit Ad , Verhoef Jan , Hadding Ulrich , Heinz Hans-Peter , Köhrer Karl
Published: October 2018

One hundred sixteen unrelated clinical isolates of
Staphylococcus aureus
(70 ciprofloxacin resistant and 46 ciprofloxacin susceptible) from eight countries were studied for the presence of mutations in the
grlA
,
grlB
,
gyrA
, and
gyrB
gene loci. Two mutations within
grlA
(located at codons 80 and 84) and two mutations within
gyrA
(located at codons 84 and 88) were clearly associated with ciprofloxacin resistance, although other mutations detected within the four genes studied may also contribute to decreased susceptibility.
Assessment of the Effects of Combination Therapy with Ciprofloxacin and Fenbufen on the Central Nervous Systems of Healthy Volunteers by Quantitative Electroencephalography
Authors: Kamali F. , Ashton C. H. , Marsh V. R. , Cox J.
Published: October 2018

The potential effects of concurrent administration of fenbufen and ciprofloxacin on central nervous system activity in healthy young subjects were investigated by electroencephalography (EEG). Visual analog scales (VAS) were used to assess subjective measures of concentration, vigilance, tension, and irritability. When ciprofloxacin was administered in combination with fenbufen, none of the EEG parameters or VAS ratings measured were significantly different from those measured when the drugs were administered alone.
In Vitro Antimicrobial Effects of Various Combinations of Penicillin and Clindamycin against Four Strains of
Streptococcus pyogenes
Authors: Stevens Dennis L. , Madaras-Kelly Karl J. , Richards David M.
Published: October 2018

Previous studies using mouse models of
Streptococcus pyogenes
necrotizing fasciitis demonstrated that clindamycin had greater efficacy than penicillin. Frequently both agents are used concurrently in the treatment of severe
S. pyogenes
infections. This study investigated interactions between penicillin and clindamycin. E-test and broth microdilution assays suggested additivity or indifference, while timed-killing assays demonstrated concentration-dependent variable effects. Timed-kill studies utilizing clinical concentrations suggest that there is no antagonism with the combination of drugs but that the combination does not have a bactericidal advantage over either penicillin or clindamycin alone.
Susceptibilities of Neonatal Respiratory Isolates of
Ureaplasma urealyticum
to Antimicrobial Agents
Authors: Matlow Anne , Th’ng Cecilia , Kovach Danuta , Quinn Patricia , Dunn Michael , Wang Elaine
Published: October 2018

Twenty-one neonatal respiratory isolates of
Ureaplasma urealyticum
were serotyped, and their susceptibilities to ciprofloxacin, gentamicin, chloramphenicol, erythromycin, azithromycin, and doxycycline were tested. Most patient strains were
Ureaplasma urealyticum
bv. parvum. Chloramphenicol, doxycycline, and azithromycin had the lowest MICs. This data may be useful when designing prophylactic or therapeutic trials of antibiotics for chronic lung disease of the newborn.
Pharmacokinetic Studies of Fluconazole in Rabbits Characterizing Doses Which Achieve Peak Levels in Serum and Area under the Concentration-Time Curve Values Which Mimic Those of High-Dose Fluconazole in Humans
Authors: Louie Arnold , Liu Qing-Feng , Drusano George L. , Liu Weiguo , Mayers Martin , Anaissie Elias , Miller Michael H.
Published: October 2018

We conducted steady-state pharmacokinetic studies with high-dose fluconazole with rabbits and human volunteers. We then derived mathematical equations that predict the doses of fluconazole that should be given to rabbits to produce 24-h area under the concentration-time curve values and maximum concentrations in serum that are similar to those measured for humans given 800 to 2,000 mg of fluconazole per day. These equations provide a rational basis for designing future efficacy studies with rabbits and in evaluating the strength with which results of previously conducted studies using rabbit infection models can be extrapolated to the clinic.
Inhibition of Hyphal Growth of Azole-Resistant Strains of
Candida albicans
by Triazole Antifungal Agents in the Presence of Lactoferrin-Related Compounds
Authors: Wakabayashi Hiroyuki , Abe Shigeru , Teraguchi Susumu , Hayasawa Hirotoshi , Yamaguchi Hideyo
Published: October 2018

The effects of bovine lactoferrin (LF) or the LF-derived antimicrobial peptide lactoferricin B (LFcin B) on the growth of
Candida albicans
hyphae, including those of three azole-resistant strains, were investigated by a crystal violet staining method. The hyphae of two highly azole-resistant strains were more susceptible to inhibition by LF or LFcin B than the azole-susceptible strains tested. One moderately azole-resistant strain was defective in the formation of hyphae and showed a susceptibility to LF greater than that of the susceptible strains but a susceptibility to LFcin B similar to that of the susceptible strains. The highly azole-resistant strain TIMM3317 showed trailing growth in the presence of fluconazole or itraconazole, while the extent of growth was reduced by the addition of LF or LFcin B at a sub-MIC. Thus, the addition of LF or LFcin B at a sub-MIC resulted in a substantial decrease in the MICs of fluconazole and itraconazole for two highly azole-resistant strains; e.g., the MIC of fluconazole for TIMM3317 was shifted from >256 to 0.25 μg/ml by LF, but the MICs were not decreased for the susceptible strains. The combination effects observed with triazoles and LF-related compounds in the case of the two highly azole-resistant strains were confirmed to be synergistic by the fractional inhibitory concentration index. These results demonstrate that for some azole-resistant
C. albicans
strains, LF-related compounds combined with triazoles can inhibit the growth of hyphae, an important form of this organism in pathogenesis.