bluuebunny/crossref_metadata_2025 huggingface dataset:
Active efflux as a mechanism of resistance to ciprofloxacin in Streptococcus pneumoniae
Authors: Zeller V , Janoir C , Kitzis M D , Gutmann L , Moreau N J
Published: October 2018

The accumulation of fluoroquinolones (FQs) was studied in a FQ-susceptible laboratory strain of Streptococcus pneumoniae (strain R6). Uptake of FQs was not saturable, was rapidly reversible, and appeared to occur by passive diffusion. In the presence of glucose, which energizes bacteria, the uptake of FQs decreased. Inhibitors of the proton motive force and ATP synthesis increased the uptake of FQs in previously energized bacteria. Similar results were observed with the various FQs tested and may be explained to be a consequence simply of the pH gradient that exists across the cytoplasmic membrane. From a clinical susceptible strain (strain SPn5907) we isolated in vitro on ciprofloxacin an FQ-resistant mutant (strain SPn5929) for which the MICs of hydrophilic molecules were greater than those of hydrophobic molecules, and the mutant was resistant to acriflavine, cetrimide, and ethidium bromide. Strain SPn5929 showed a significantly decreased uptake of ciprofloxacin, and its determinant of resistance to ciprofloxacin was transferred by transformation to susceptible laboratory strain R6 (strain R6tr5929). No mutations in the quinolone resistance-determining regions of the gyrA and parC genes were found. In the presence of arsenate or carbonyl cyanide m-chlorophenylhydrazone, the levels of uptake of ciprofloxacin by the two resistant strains, SPn5929 and R6tr5929, reached the levels of uptake of their susceptible parents. These results suggest an active efflux of ciprofloxacin in strain SPn5929.
Nephrotoxicity of vancomycin and drug interaction study with cilastatin in rabbits
Authors: Toyoguchi T , Takahashi S , Hosoya J , Nakagawa Y , Watanabe H
Published: October 2018

The nephrotoxic effects of vancomycin hydrochloride (VCM) and the potential drug-drug interaction with cilastatin sodium (CS) were examined in rabbits. The aim of the study was to measure the possible dose-related suppressive effects or elimination by cilastatin of the adverse reactions generated by vancomycin in the kidneys of rabbits. To clarify the interactions of these two drugs, we examined the nephrotoxicity and pharmacokinetics of VCM in the rabbit when administered alone and when coadministered with CS. VCM administered alone (300 mg/kg of body weight as an intravenous bolus; n = 5) caused typical symptoms of nephrotoxicity, such as increases in serum creatinine and blood urea nitrogen (BUN) levels, as well as morphological changes in the kidneys. A lack of such signs of nephrotoxicity was observed in the groups administered VCM plus CS (i.e., CS at 150 mg/kg plus VCM at 300 mg/kg or CS at 300 mg/kg plus VCM at 300 mg/kg, intravenous bolus; n = 5/group). At a reduced combination ratio of VCM plus CS (4:1 ratio, VCM at 300 mg/kg plus CS at 75 mg/kg, intravenous bolus; n = 5) some symptoms of nephrotoxicity induced by VCM were present, but the degree of this effect was much reduced and was significantly different from preadministration values by only modest increases of the BUN and N-acetyl-beta-D-glucosaminidase levels (P < 0.05). Overall clearance of VCM was accelerated by coadministration of CS and was found to be dose dependent upon CS. No changes in renal function values from the preadministration values were observed for animals receiving CS alone (300 mg/kg, intravenous bolus; n = 3). These results suggest that CS has the ability to reduce or eliminate in a dose-dependent manner the nephrotoxic effects caused by VCM administration in rabbits.
Penicillin-binding proteins and induction of AmpC beta-lactamase
Authors: Sanders C C , Bradford P A , Ehrhardt A F , Bush K , Young K D , Henderson T A , Sanders W E
Published: October 2018

In competition assays for radiolabeled penicillin, penicillin-binding proteins (PBPs) 4, 7a, and 7b showed very high affinities for strong inducers of AmpC beta-lactamase. Loss of PBP 4 resulted in diminished inducibility. This suggests that if PBPs are involved in induction of AmpC beta-lactamase, there is probably a redundancy in function among the different PBPs.
Efficacy of nikkomycin Z against experimental pulmonary blastomycosis
Authors: Clemons K V , Stevens D A
Published: October 2018

Nikkomycin Z is a chitin synthetase inhibitor. In vitro, nikkomycin Z had good activity against Blastomyces dermatitidis, with an MIC of 0.78 microg/ml and a minimal fungicidal concentration of 3.1 microg/ml. The efficacies of various treatment durations (3, 5, or 10 days) and doses (200, 400, or 1,000 mg/kg of body weight) of nikkomycin Z given twice daily were compared with those of itraconazole at 200 mg/kg given twice daily and amphotericin B at 6.25 mg/kg in a murine model of pulmonary blastomycosis. All treatments prolonged survival compared with untreated controls (P < 0.05 to 0.01); 100% survival was achieved with 5 or 10 days of any nikkomycin Z dose or with amphotericin B. Amphotericin B and nikkomycin Z, but not itraconazole, reduced infection compared with controls. Amphotericin B and the 10-day regimens of all nikkomycin Z doses were equivalent and superior to itraconazole or nikkomycin Z for < or = 5 days at any dose (P < 0.05 to 0.01). Increased duration and/or dosage improved the efficacy of nikkomycin Z, with 10 days of each dose curing 50 to 90% of the animals. Only a 1,000-mg/kg/day dose of nikkomycin Z was curative when treatment lasted less than 10 days. In contrast, itraconazole cured no mice, while amphotericin B cured all mice. Based on the total amount of drug given, amphotericin B was estimated to be 32 times as active as nikkomycin Z and nikkomycin Z was estimated to be 3 times as active as itraconazole. Overall, nikkomycin Z given orally was well tolerated, had good activity against blastomycosis, and could result in biological cure, thus producing results equivalent to those of parenteral amphotericin B.
In vitro activity of trovafloxacin against Chlamydia pneumoniae
Authors: Roblin P M , Kutlin A , Hammerschlag M R
Published: October 2018

The in vitro susceptibilities of 12 strains of Chlamydia pneumoniae to a new quinolone, trovafloxacin, and ofloxacin, doxycycline, erythromycin, and azithromycin were determined. The activity of trovafloxacin was similar to that of ofloxacin, with a MIC at which 90% of the isolates are inhibited and a minimal concentration at which 90% of the isolates are killed of 1.0 microg/ml, but trovafloxacin was less active than doxycycline, erythromycin, and azithromycin.
Bactericidal activity against intermediately cephalosporin-resistant Streptococcus pneumoniae in cerebrospinal fluid of children with bacterial meningitis treated with high doses of cefotaxime and vancomycin
Authors: Doit C , Barre J , Cohen R , Bonacorsi S , Bourrillon A , Bingen E H
Published: October 2018

Cerebrospinal fluid (CSF) was taken from 19 children with bacterial meningitis treated with cefotaxime (300 mg/kg of body weight/day) and vancomycin (60 mg/kg/day). Median levels of drugs in CSF were smaller than expected, as follows: 4.4 microg/ml for cefotaxime, 3.2 microg/ml for desacetylcefotaxime, and 1.7 microg/ml for vancomycin. The median CSF bactericidal titer against an intermediately cefotaxime-resistant pneumococcus was 1:4. Our data suggest at least an additive interaction between the drugs used in this study.
Analysis of ahpC gene mutations in isoniazid-resistant clinical isolates of Mycobacterium tuberculosis
Authors: Kelley C L , Rouse D A , Morris S L
Published: October 2018

The ahpC genes of 57 clinical isolates and one in vitro mutant of Mycobacterium tuberculosis were evaluated by nucleotide sequence analyses. Although compensatory ahpC promoter mutations were identified in 8 catalase-negative, katG-defective strains, the ahpC genes of 25 catalase-positive, isoniazid-resistant isolates and 25 drug-sensitive strains were not altered.
Dicaffeoylquinic and Dicaffeoyltartaric Acids Are Selective Inhibitors of Human Immunodeficiency Virus Type 1 Integrase
Authors: McDougall Brenda , King Peter J. , Wu Bor Wen , Hostomsky Zdenek , Reinecke Manfred G. , Robinson W. Edward
Published: October 2018

Current pharmacological agents for human immunodeficiency virus (HIV) infection include drugs targeted against HIV reverse transcriptase and HIV protease. An understudied therapeutic target is HIV integrase, an essential enzyme that mediates integration of the HIV genome into the host chromosome. The dicaffeoylquinic acids (DCQAs) and the dicaffeoyltartaric acids (DCTAs) have potent activity against HIV integrase in vitro and prevent HIV replication in tissue culture. However, their specificity against HIV integrase in cell culture has been questioned. Thus, the ability of the DCQAs and DCTAs to inhibit binding of HIV type 1 (HIV-1) gp120 to CD4 and their activities against HIV-1 reverse transcriptase and HIV RNase H were studied. The DCQAs and DCTAs inhibited HIV-1 integrase at concentrations between 150 and 840 nM. They inhibited HIV replication at concentrations between 2 and 12 μM. Their activity against reverse transcriptase ranged from 7 μM to greater than 100 μM. Concentrations that inhibited gp120 binding to CD4 exceeded 80 μM. None of the compounds blocked HIV-1 RNase H by 50% at concentrations exceeding 80 μM. Furthermore, when the effects of the DCTAs on reverse transcription in acutely infected cells were measured, they were found to have no activity. Therefore, the DCQAs and DCTAs exhibit >10- to >100-fold specificity for HIV integrase, and their activity against integrase in biochemical assays is consistent with their observed anti-HIV activity in tissue culture. Thus, the DCQAs and DCTAs are a potentially important class of HIV inhibitors that act at a site distinct from that of current HIV therapeutic agents.
Atomic Force Microscopy: Application to Investigation of
Escherichia coli
Morphology before and after Exposure to Cefodizime
Authors: Braga Pier Carlo , Ricci Davide
Published: October 2018

Atomic force microscopy (AFM) is a recently developed technique that allows for the investigation of the surface morphology of a biological specimen at an unprecedented level of resolution. The aim of the present study was to explore some of the new opportunities offered by AFM by studying the morphological and surface alterations induced in
Escherichia coli
by supra-MICs and sub-MICs of a beta-lactam antibiotic (cefodizime). The underlying principle of AFM is the scanning and sensing of the topography of a sample by means of near-field microscopy that makes it possible to obtain simultaneous digital measurements of the
x
,
y
, and
z
coordinates of any point on the bacterial surface with great resolution (
x
and
y
, ∼20 Å;
z
, ∼1 Å). Unlike scanning electron microscopy, performance of AFM does not require a vacuum, drying to the critical point, or the coating of the bacterial surface with a metal layer. The digital storage of the information makes it easy to rotate the image, observe the bacterial surface and induced structural alterations from different points of view, and obtain a cross-section at any desired point with precise, automatic measurement of the heights and sizes of normal versus damaged bacteria. Use of the new and outstanding technique of AFM will make it possible for researchers to investigate biological samples immersed in biological fluids and will also make it possible for them to study the morphological alterations of living bacteria exposed to antibiotics as they are taking place.
Comparison of CO
2
Generation (BACTEC) and Viable-Count Methods To Determine the Postantibiotic Effect of Antimycobacterial Agents against
Mycobacterium avium
Complex
Authors: Zhanel George G. , Saunders Marilyn H. , Wolfe Joyce N. , Hoban Daryl J. , Karlowsky James A. , Kabani Amin M.
Published: October 2018

The postantibiotic effects (PAEs) of antimycobacterial agents determined with a BACTEC TB-460 instrument (CO
2
production) and by a traditional viable-count method against
Mycobacterium avium
complex (MAC) were not significantly different (
P
> 0.05). The longest PAEs following a 2-h exposure to 2× the MIC were induced by amikacin (10.3 h), rifampin (9.7 h), and rifabutin (9.5 h), while the shortest PAEs resulted from clofazimine (1.7 h) and ethambutol (1.1 h) exposure. CO
2
generation is a valid and efficient means of determining in vitro PAEs against MAC.
Treatment of Enterococcal Pyelonephritis with Trovafloxacin and Rifampin: In Vitro-In Vivo Contrast
Authors: Montgomerie J. Z. , Schick D. G.
Published: October 2018

The in vitro bactericidal interaction of trovafloxacin and rifampin against
Enterococcus
spp. has indicated that antagonism occurs between these two antimicrobial agents. This drug combination was examined in vivo in rats with experimental pyelonephritis. The rats received trovafloxacin, rifampin, or both drugs. On the basis of the mean log
10
CFU of
Enterococcus faecalis
from the kidneys, there was no evidence that trovafloxacin and rifampin were antagonistic in vivo.
Cloning and Nucleotide Sequence of the DNA Gyrase
gyrA
Gene from
Serratia marcescens
and Characterization of Mutations in
gyrA
of Quinolone-Resistant Clinical Isolates
Authors: Kim Jeong Hoon , Cho Eun Hee , Kim Kwang Seo , Kim Hak Yeop , Kim Young Min
Published: October 2018

The sequence of the DNA gyrase
gyrA
gene of
Serratia marcescens
ATCC 14756 was determined. An open reading frame of 2,640 nucleotides coding for a polypeptide with a calculated molecular mass of 97,460 was found, and its sequence complemented the sequence of an
Escherichia coli gyrA
temperature-sensitive mutation. Analysis of the PCR products of the quinolone resistance-determining regions of
gyrA
genes from six quinolone-resistant clinical isolates revealed a single amino acid substitution, Ser-83 to Arg or Asp-87 to Tyr, in all six mutants, suggesting that a mutational alteration in
gyrA
is a common mechanism of quinolone resistance in
S. marcescens.
DNA Sequence Variation within
vanA
,
vanB
,
vanC-1
, and
vanC-2/3
Genes of Clinical
Enterococcus
Isolates
Authors: Patel Robin , Uhl Jim R. , Kohner Peggy , Hopkins Marlene K. , Steckelberg James M. , Kline Bruce , Cockerill Franklin R.
Published: October 2018

We studied the DNA sequence variation of
van
genes of 34 isolates of
Enterococcus
spp. The isolates containing the
vanB
gene exhibited between 0 and 41 base pair changes per 801 bp studied when the
vanB
sequences were compared to that of the reference strain
Enterococcus faecalis
V583. The isolates carrying the
vanC-2
gene exhibited between 0 and 23 base pair changes per 346 bp studied when the
vanC-2
sequences were compared to that of the reference strain
E. casseliflavus
ATCC 25788. Little variation was noted in the
vanA
and
vanC-1
genes.
Therapeutic Effects of Water-Soluble Echinocandin Compounds on
Pneumocystis
Pneumonia in Mice
Authors: Furuta Takahisa , Muramatsu Hideyuki , Fujie Akihiko , Fujihira Shiro , Rain Abudullah Noor , Kojima Somei
Published: October 2018

The therapeutic effectiveness of water-soluble echinocandin compounds obtained from
Coleophoma empetri
F-11899, which has a strong inhibitory effect on the growth of fungi, was examined in nude mice with experimental
Pneumocystis
pneumonia. The studies demonstrated the potential usefulness of the compounds.
Long-Circulating Immunoliposomal Amphotericin B against Invasive Pulmonary Aspergillosis in Mice
Authors: Otsubo Takakazu , Maruyama Kazuo , Maesaki Shigefumi , Miyazaki Yoshitsugu , Tanaka Eitaro , Takizawa Tomoko , Moribe Kunikazu , Tomono Kazunori , Tashiro Takayoshi , Kohno Shigeru
Published: October 2018

We investigated the efficacy of long-circulating immunoliposomal amphotericin B (AmB) against invasive pulmonary aspergillosis in mice using three types of liposomal AmB: conventional liposomal AmB (AmBisome), a long-circulating liposomal AmB and prepared by coating the liposome surface with polyethylene glycol (PEG; PEG-L-AmB), long-circulating immunoliposomal AmB (34A-PEG-L-AmB). The survival rates for mice with invasive pulmonary aspergillosis treated with an intravenous dose of 2 mg of AmBisome, PEG-L-AmB, or 34A-PEG-L-AmB per kg of body weight were 16.7, 83.3, and 100%, respectively. Treatment with 34A-PEG-L-AmB produced a marked reduction in the number of
Aspergillus fumigatus
organisms in the lungs. Pharmacokinetic studies showed the presence of high AmB concentrations in the plasma of mice treated with PEG-L-AmB (40.8 μg/ml) and in the lungs of mice treated with 34A-PEG-L-AmB (42.3 μg/g). We conclude that 34A-PEG-L-AmB, a long-circulating immunoliposomal AmB, is a promising form of AmB against invasive pulmonary aspergillosis.
Postantibiotic Effect in
Escherichia coli
Determined with Real-Time Metabolic Monitoring
Authors: Libby Jeffrey M.
Published: October 2018

Metabolic activity was used to quantify the delay in recovery of
Escherichia coli
after limited exposures to cefotaxime and piperacillin. This was measured with a microphysiometer, a device which measures changes in pH in the cellular environment, which in turn reflects the metabolic activity of the cells. The antibiotics were rapidly pumped into and flushed from each cellular environment. The length of time that the bacteria were exposed to either antibiotic was determined by programmed valve changes. Metabolic activity was measured during periods in which the instrument’s pumps were off. Graphical analysis of the data was used to determine the postantibiotic effect. The lengths of the postantibiotic effects of both drugs (95 to 101 min) determined with the microphysiometer corresponded with the reappearance of short, highly motile cells in significant numbers.
Mucoadhesive Microspheres Containing Amoxicillin for Clearance of
Helicobacter pylori
Authors: Nagahara Naoki , Akiyama Yohko , Nakao Masafumi , Tada Mayumi , Kitano Megumi , Ogawa Yasuyuki
Published: October 2018

In an effort to augment the anti-
Helicobacter pylori
effect of amoxicillin, mucoadhesive microspheres, which have the ability to reside in the gastrointestinal tract for an extended period, were prepared. The microspheres contained the antimicrobial agent and an adhesive polymer (carboxyvinyl polymer) powder dispersed in waxy hydrogenated castor oil. The percentage of amoxicillin remaining in the stomach both 2 and 4 h after oral administration of the mucoadhesive microspheres to Mongolian gerbils under fed conditions was about three times higher than that after administration in the form of a 0.5% methylcellulose suspension. The in vivo clearance of
H. pylori
following oral administration of the mucoadhesive microspheres and the 0.5% methylcellulose suspension to infected Mongolian gerbils was examined under fed conditions. The mucoadhesive microspheres and the 0.5% methylcellulose suspension both showed anti-
H. pylori
effects in this experimental model of infection, but the required dose of amoxicillin was effectively reduced by a factor of 10 when the mucoadhesive microspheres were used. In conclusion, the mucoadhesive microspheres more effectively cleared
H. pylori
from the gastrointestinal tract than the 0.5% methylcellulose suspension due to the prolonged gastrointestinal residence time resulting from mucoadhesion. A dosage form consisting of mucoadhesive microspheres containing an appropriate antimicrobial agent should be useful for the eradication of
H. pylori
.
Interleukin-12 Enhances In Vivo Parasiticidal Effect of Benznidazole during Acute Experimental Infection with a Naturally Drug-Resistant Strain ofTrypanosoma cruzi
Authors: Michailowsky Vladimir , Murta Silvane M. F. , Carvalho-Oliveira Leonardo , Pereira Maria E. S. , Ferreira Ludmila R. P. , Brener Zigman , Romanha Alvaro J. , Gazzinelli Ricardo T.
Published: October 2018

The roles of gamma interferon (IFN-γ) and interleukin-12 (IL-12) in mediating and/or enhancing the in vivo trypanosomicidal activity of the nitroheterocyclic derivative benznidazole (Bz) were evaluated during early stages of experimental Chagas’ disease. Our results show that treatment ofTrypanosoma cruzi-infected mice with anti-cytokine monoclonal antibodies (MAbs) had no apparent effect when the optimal dose of Bz (100 mg/kg of body weight) was used. In contrast, treatment with anti-IL-12 or anti-IFN-γ MAbs enhanced the parasitemia and accelerated the mortality of mice treated with a suboptimal dose of Bz (25 mg/kg). Simultaneous treatment with a suboptimal dose of Bz and recombinant IL-12 (rIL-12) enhanced the efficacy of drug treatment in terms of parasitemia and mouse survival. Interestingly, we found that drug-resistantT. cruzistrains were found to be poor inducers of IL-12 both in vitro and in vivo compared to strains ofT. cruziwhich are susceptible or partially resistant to Bz treatment. These results suggest that early activation of the cellular compartment of the immune system by IL-12 may favor in vivo Bz activity againstT. cruzi. In order to test this hypothesis mice infected with the drug-resistant Colombiana strain ofT. cruziwere treated with 100 mg of Bz per kg plus different concentrations of rIL-12. By using the results of PCR and serological and parasitological methods as the criteria of a cure, our results indicate that a higher percentage of mice treated with Bz combined with rIL-12 than mice treated with Bz alone are cured.
Characterization of a Glycosyl Transferase Inactivating Macrolides, Encoded by
gimA
from
Streptomyces ambofaciens
Authors: Gourmelen Anne , Blondelet-Rouault Marie-Hélène , Pernodet Jean-Luc
Published: October 2018

In
Streptomyces ambofaciens
, the producer of the macrolide antibiotic spiramycin, an open reading frame (ORF) was found downstream of
srmA
, a gene conferring resistance to spiramycin. The deduced product of this ORF had high degrees of similarity to
Streptomyces lividans
glycosyl transferase, which inactivates macrolides, and this ORF was called
gimA
. The cloned
gimA
gene was expressed in a susceptible host mutant of
S. lividans
devoid of any background macrolide-inactivating glycosyl transferase activity. In the presence of UDP-glucose, cell extracts from this strain could inactivate various macrolides by glycosylation. Spiramycin was not inactivated but forocidin, a spiramycin precursor, was modified. In vivo studies showed that
gimA
could confer low levels of resistance to some macrolides. The spectrum of this resistance differs from the one conferred by a rRNA monomethylase, such as SrmA. In
S. ambofaciens
,
gimA
was inactivated by gene replacement, without any deleterious effect on the survival of the strain, even under spiramycin-producing conditions. But the overexpression of
gimA
led to a marked decrease in spiramycin production. Studies with extracts from wild-type and
gimA
-null mutant strains revealed the existence of another macrolide-inactivating glycosyl transferase activity with a different substrate specificity. This activity might compensate for the effect of
gimA
inactivation.
Use of Microsphere Technology for Targeted Delivery of Rifampin to
Mycobacterium tuberculosis
-Infected Macrophages
Authors: Barrow Esther L. W. , Winchester Gary A. , Staas Jay K. , Quenelle Debra C. , Barrow William W.
Published: October 2018

Microsphere technology was used to develop formulations of rifampin for targeted delivery to host macrophages. These formulations were prepared by using biocompatible polymeric excipients of lactide and glycolide copolymers. Release characteristics were examined in vitro and also in two monocytic cell lines, the murine J774 and the human Mono Mac 6 cell lines. Bioassay assessment of cell culture supernatants from monocyte cell lines showed release of bioactive rifampin during a 7-day experimental period. Treatment of
Mycobacterium tuberculosis
H37Rv-infected monocyte cell lines with rifampin-loaded microspheres resulted in a significant decrease in numbers of CFU at 7 days following initial infection, even though only 8% of the microsphere-loaded rifampin was released. The levels of rifampin released from microsphere formulations within monocytes were more effective at reducing
M. tuberculosis
intracellular growth than equivalent doses of rifampin given as a free drug. These results demonstrate that rifampin-loaded microspheres can be formulated for effective sustained and targeted delivery to host macrophages.
Proteasome Inhibitors Block Development of
Plasmodium
spp
Authors: Gantt Soren M. , Myung Joon Mo , Briones Marcelo R. S. , Li Wei Dong , Corey E. J. , Omura Satoshi , Nussenzweig Victor , Sinnis Photini
Published: October 2018

Proteasomes degrade most of the proteins inside eukaryotic cells, including transcription factors and regulators of cell cycle progression. Here we show that nanomolar concentrations of lactacystin, a specific irreversible inhibitor of the 20S proteasome, inhibit development of the exoerythrocytic and erythrocytic stages of the malaria parasite. Although lactacystin-treated
Plasmodium berghei
sporozoites are still invasive, their development into exoerythrocytic forms (EEF) is inhibited in vitro and in vivo. Erythrocytic schizogony of
P. falciparum
in vitro is also profoundly inhibited when drug treatment of the synchronized parasites is prior, but not subsequent, to the initiation of DNA synthesis, suggesting that the inhibitory effect of lactacystin is cell cycle specific. Lactacystin reduces
P. berghei
parasitemia in rats, but the therapeutic index is very low. Along with other studies showing that lactacystin inhibits stage-specific transformation in
Trypanosoma
and
Entamoeba
spp., these findings highlight the potential of proteasome inhibitors as drugs for the treatment of diseases caused by protozoan parasites.
In Vitro Susceptibility of
Coxiella burnetii
to Trovafloxacin in Comparison with Susceptibilities to Pefloxacin, Ciprofloxacin, Ofloxacin, Doxycycline, and Clarithromycin
Authors: Gikas Achilleas , Spyridaki Ioanna , Psaroulaki Anna , Kofterithis Diamantis , Tselentis Yannis
Published: October 2018

The antibiotic susceptibilities of eight Greek isolates of
Coxiella burnetii
to trovafloxacin were determined by the shell vial assay. MICs of trovafloxacin and ofloxacin ranged from 1 to 2 μg/ml, those of pefloxacin ranged from 1 to 4 μg/ml, those of ciprofloxacin ranged from 4 to 8 μg/ml, those of doxycycline ranged from 1 to 2 μg/ml, and those of clarithromycin ranged from 2 to 4 μg/ml. Trovafloxacin exhibited no activity against
C. burnetii
at 4 μg/ml.
Fluoroquinolone Resistance Mutations in the
parC
,
parE
, and
gyrA
Genes of Clinical Isolates of Viridans Group Streptococci
Authors: González Irene , Georgiou Marios , Alcaide Fernando , Balas Delia , Liñares Josefina , de la Campa Adela G.
Published: October 2018

The nucleotide sequences of the quinolone resistance-determining regions (QRDRs) of the
parC
and
gyrA
genes from seven ciprofloxacin-resistant (Cp
r
) isolates of viridans group streptococci (two high-level Cp
r
Streptococcus oralis
and five low-level Cp
r
Streptococcus mitis
isolates) were determined and compared with those obtained from susceptible isolates. The nucleotide sequences of the QRDRs of the
parE
and
gyrB
genes from the five low-level Cp
r
S. mitis
isolates and from the NCTC 12261 type strain were also analyzed. Four of these low-level Cp
r
isolates had changes affecting the subunits of DNA topoisomerase IV: three in Ser-79 (to Phe or Ile) of ParC and one in ParE at a position not previously described to be involved in quinolone resistance (Pro-424). One isolate did not show any mutation. The two high-level Cp
r
S. oralis
isolates showed mutations affecting equivalent residue positions of ParC and GyrA, namely, Ser-79 to Phe and Ser-81 to Phe or Tyr, respectively. The
parC
mutations were able to transform
Streptococcus pneumoniae
to ciprofloxacin resistance, while the
gyrA
mutations transformed
S. pneumoniae
only when mutations in
parC
were present. These results suggest that DNA topoisomerase IV is a primary target of ciprofloxacin in viridans group streptococci, DNA gyrase being a secondary target.
Distinct Patterns of Gene Expression Associated with Development of Fluconazole Resistance in Serial
Candida albicans
Isolates from Human Immunodeficiency Virus-Infected Patients with Oropharyngeal Candidiasis
Authors: Lopez-Ribot Jose L. , McAtee Robert K. , Lee Linda N. , Kirkpatrick William R. , White Theodore C. , Sanglard Dominique , Patterson Thomas F.
Published: October 2018

Resistance to fluconazole is becoming an increasing problem in the management of oropharyngeal candidiasis in human immunodeficiency virus-infected patients. Strains obtained from five patients developed decreased fluconazole susceptibility over time. DNA strain typing confirmed the high degree of relatedness among isolates from one patient and the variability among isolates from different patients. Expression of genes involved in development of fluconazole resistance was monitored in each isolate using probes specific for
ERG11
(lanosterol 14α-demethylase),
MDR1
(a major facilitator), and
CDR
(ATP-binding cassette or ABC transporter) genes. Increased expression of
CDR
genes was detected in the series of isolates from two patients. Isolates from one of the two patients also demonstrated increased
ERG11
expression, whereas isolates from the other patient did not. Increased levels of
MDR1
mRNA correlated with increased resistance in sequential isolates from another patient. Initial overexpression of
MDR1
with subsequent overexpression of
CDR
genes and a final isolate again overexpressing
MDR1
were detected in serial isolates from another patient. In another patient, overexpression of these genes was not detected despite an eightfold increase in fluconazole MIC. In this patient, sequence data of the
ERG11
gene revealed no point mutations associated with decreased susceptibility. Five different patterns of gene expression were observed in isolates recovered from five patients who developed resistance. Therefore, these experiments demonstrate that a variety of mechanisms or combinations of mechanisms are associated with the development of fluconazole drug resistance. Additional studies are needed to estimate the frequency and clinical impact of these mechanisms of resistance.
In Vitro and In Vivo Antibacterial Activities of OPC-20011, a Novel Parenteral Broad-Spectrum 2-Oxaisocephem Antibiotic
Authors: Matsumoto Makoto , Tamaoka Hisashi , Ishikawa Hiroshi , Kikuchi Mikio
Published: October 2018

OPC-20011, a new parenteral 2-oxaisocephem antibiotic, has an oxygen atom at the 2- position of the cephalosporin frame. OPC-20011 had the best antibacterial activities against gram-positive bacteria, including methicillin-resistant
Staphylococcus aureus
(MRSA),
Enterococcus faecalis
, and penicillin-resistant
Streptococcus pneumoniae
: MICs at which 90% of the isolates were inhibited were 6.25, 6.25, and 0.05 μg/ml, respectively. Its activity is due to a high affinity of the penicillin-binding protein 2′ in MRSA, an affinity which was approximately 1,050 times as high as that for flomoxef. Against gram-negative bacteria, OPC-20011 also showed antibacterial activities similar to those of ceftazidime. The in vivo activities of OPC-20011 were comparable to or greater than those of reference compounds in murine models of systemic infection caused by gram-positive and -negative pathogens. OPC-20011 was up to 10 times as effective as vancomycin against MRSA infections in mice. This better in vivo efficacy is probably due to the bactericidal activity of OPC-20011, while vancomycin showed bacteriostatic activity against MRSA. OPC-20011 produced a significant decrease of viable counts in lung tissue at a dose of 2.5 mg/kg of body weight, an efficacy similar to that of ampicillin at a dose of 10 to 20 mg/kg on an experimental murine model of respiratory tract infection caused by non-ampicillin-susceptible
S. pneumoniae
T-0005. The better therapeutic efficacy of OPC-20011 was considered to be due to its potent antibacterial activity and low affinity for serum proteins of experimental animals (29% in mice and 6.4% in rats).
A Multicenter Phase I/II Dose Escalation Study of Single-Dose Cidofovir Gel for Treatment of Recurrent Genital Herpes
Authors: Sacks Stephen L. , Shafran Stephen D. , Diaz-Mitoma Francisco , Trottier Sylvie , Sibbald R. Gary , Hughes April , Safrin Sharon , Rudy Jeff , McGuire Brian , Jaffe Howard S.
Published: October 2018

A randomized, double-blind, clinic-initiated, sequential dose-escalation pilot study was performed to compare the safety and efficacy of single applications of 1, 3, and 5% cidofovir gel with placebo in the treatment of early, lesional, recurrent genital herpes at five Canadian outpatient sites. Ninety-six patients began treatment within 12 h of lesion appearance and were evaluated twice daily until healing of the lesion occurred. Cidofovir gel at all strengths significantly decreased the median time to negative virus culture in a dose-dependent fashion (3.0 days in the placebo group versus 2.2, 1.3, and 1.1 days in the 1, 3, and 5% cidofovir gel treatment groups, respectively;
P
= 0.02, 0.0001, and 0.0003, respectively). A trend toward a reduction in the median time to complete healing in association with treatment was present, but the differences were not statistically significant (5.0 days in the placebo group versus 4.3, 4.1, and 4.6 days in the 1, 3, and 5% cidofovir gel treatment groups, respectively). Application site reactions occurred in 3, 5, 19, and 22% of the patients in these four groups, respectively. Treatment-associated lesion recrudescence with delayed healing, which is suggestive of local toxicity, was observed in three patients treated with 5% cidofovir gel and one patient treated with 3% cidofovir gel. In summary, single-dose application of cidofovir gel confers a significant antiviral effect on lesions of recurrent genital herpes. Additional studies are warranted to further identify the optimal efficacious dose of cidofovir in association with the maximum gel strength that can be tolerated.
In Vitro Activity of a New Polyene, SPA-S-843, against Yeasts
Authors: Rimaroli C. , Bruzzese T.
Published: October 2018

The in vitro activity of a new water-soluble polyene, SPA-S-843, was evaluated against 116 strains of
Candida
,
Cryptococcus
, and
Saccharomyces
spp. and compared with that of amphotericin B. SPA-S-843 demonstrated better inhibitory activity against all of the yeasts examined and better fungicidal activity against
Candida albicans
,
Candida glabrata
,
Candida krusei
, and
Candida tropicalis
than did amphotericin B.
Organism-Dependent Fungicidal Activities of Azoles
Authors: Manavathu Elias K. , Cutright Jessica L. , Chandrasekar Pranatharthi H.
Published: October 2018

We investigated the antifungal activities of itraconazole and voriconazole on
Aspergillus
species by time kill studies, and the results were compared with those obtained for
Candida
species. Exposure of
Aspergillus fumigatus
conidia to varying concentrations (1.25 to 10 μg/ml) of itraconazole and voriconazole resulted in cellular death; the cytocidal effect was time and concentration dependent. In contrast, no killing of
Candida albicans
occurred in the presence of itraconazole and voriconazole at concentrations as high as 10 μg/ml, although candidal growth was inhibited compared to the drug-free control. Amphotericin B (1.25 to 10 μg/ml), on the other hand, killed both
A. fumigatus
and
C. albicans
. Similar results were obtained for non-
A. fumigatus
aspergilli and non-
C. albicans Candida
species. These observations indicate that both itraconazole and voriconazole are cytocidal agents for
Aspergillus
species but not for
Candida
species, suggesting that azoles possess organism-dependent fungicidal activities.
Characterization of Erythromycin-Resistant Isolates of
Staphylococcus aureus
Recovered in the United States from 1958 through 1969
Authors: Nicola Federico G. , McDougal Linda K. , Biddle James W. , Tenover Fred C.
Published: October 2018

We tested 16 erythromycin-resistant clinical isolates of
S. aureus
, recovered from patients hospitalized in the United States from 1958 to 1969, for the presence of
ermA
,
ermB
, and
ermC
by using PCR. Fifteen of 16 isolates contained at least one copy of
ermA
; the remaining isolate, which was also clindamycin resistant, contained
ermB
. Eight of the 15 isolates harboring
ermA
, all of which were inducible, contained a single copy of the gene in the chromosome, while the remaining seven isolates had two copies of the gene.
ermB
was plasmid encoded and mediated constitutive resistance to erythromycin.
Bactericidal Activities of the Pyrrole Derivative BM212 against Multidrug-Resistant and Intramacrophagic
Mycobacterium tuberculosis
Strains
Authors: Deidda Delia , Lampis Giorgio , Fioravanti Rossella , Biava Mariangela , Porretta Giulio Cesare , Zanetti Stefania , Pompei Raffaello
Published: October 2018

The pyrrole derivative BM212 [1,5-diaryl-2-methyl-3-(4-methylpiperazin-1-yl)methyl-pyrrole] was shown to possess strong inhibitory activity against both
Mycobacterium tuberculosis
and some nontuberculosis mycobacteria. BM212 was inhibitory to drug-resistant mycobacteria and also exerted bactericidal activity against intracellular bacilli residing in the U937 human histiocytic lymphoma cell line.
Effect of Fluoxetine on Pharmacokinetics of Ritonavir
Authors: Ouellet Daniele , Hsu Ann , Qian Jiang , Lamm Janet E. , Cavanaugh John H. , Leonard John M. , Granneman G. Richard
Published: October 2018

The potential interaction between fluoxetine, a known inhibitor of cytochrome P-450 isoform 2D6 (CYP2D6), and ritonavir, a human immunodeficiency virus type 1 protease inhibitor, was evaluated in this open-label study. Sixteen male and female subjects ranging in age from 18 to 40 years completed the study. Subjects received single doses of 600 mg of ritonavir on days 1 and 10. On study days 3 to 10, all subjects received 30 mg of fluoxetine every 12 h for a total of 16 consecutive doses. Serial blood samples for determination of ritonavir concentrations in plasma were collected after the administration of ritonavir on days 1 and 10. A limited number of blood samples for determination of fluoxetine and norfluoxetine concentrations were collected after administration of the morning dose on day 10. A statistically significant increase (19%) in the ritonavir area under the concentration-time curve (AUC) was observed with concomitant fluoxetine administration, with individual changes ranging from −12 to +56%. The change in the ritonavir AUC with concomitant fluoxetine administration was positively correlated with the norfluoxetine 24-h AUC (AUC24) (r2= 0.42), the norfluoxetine/fluoxetine AUC24ratio (r2= 0.53), and the fluoxetine elimination rate constant (r2= 0.65), with larger increases in the ritonavir AUC tending to occur with higher norfluoxetine concentrations and higher fluoxetine elimination rate constants. The effect of fluoxetine appeared to be larger in subjects with the CYP2D6wt/wtgenotype. There was little or no effect on the time to maximum drug concentration (Cmax) in serum,Cmax, and the elimination rate constant of ritonavir with concomitant fluoxetine administration. Considering the magnitude of the change observed, no ritonavir dose adjustment is recommended during concomitant fluoxetine administration.
Patterns of Resistance and Cross-Resistance to Human Immunodeficiency Virus Type 1 Reverse Transcriptase Inhibitors in Patients Treated with the Nonnucleoside Reverse Transcriptase Inhibitor Loviride
Authors: Miller Veronica , de Béthune Marie-Pierre , Kober Astrid , Stürmer Martin , Hertogs Kurt , Pauwels Rudi , Stoffels Paul , Staszewski Schlomo
Published: October 2018

Human immunodeficiency virus type 1 (HIV-1) strains resistant to nonnucleoside reverse transcriptase inhibitors (NNRTIs) may easily be selected for in vitro and in vivo under a suboptimal therapy regimen. Although cross-resistance is extensive within this class of compounds, newer NNRTIs were reported to retain activity against laboratory strains containing defined resistance-associated mutations. We have characterized HIV-1 resistance to loviride and the extent of cross-resistance to nevirapine, delavirdine, efavirenz, HBY-097, and tivirapine in a set of 24 clinical samples from patients treated with long-term loviride monotherapy by using a recombinant virus assay. Genotypic changes associated with resistance were analyzed by population sequencing. Overall, phenotypic resistance to loviride ranged from 0.04 to 3.47 log
10
-fold. Resistance was observed in samples from patients who had discontinued loviride for up to 27 months. Cross-resistance to the other compounds was extensive; however, fold resistance to efavirenz was significantly lower than fold resistance to nevirapine. No genotypic changes were detected in three samples; these were sensitive to all of the NNRTIs tested. The most common genotypic change was the K103N substitution. The range of phenotypic resistance in samples containing the K103N substitution could not be predicted from a genotypic analysis of known NNRTI resistance-associated mutations. The Y181C substitution was detected in one isolate which was resistant to loviride and delavirdine but sensitive to efavirenz, HBY-097, and tivirapine. Our data indicate that the available newer NNRTIs which retain activity against some HIV-1 strains selected by other compounds of this class in vitro may have compromised clinical efficacy in some patients pretreated with NNRTI.
Serum and Cerebrospinal Fluid Pharmacokinetics of Intravenous and Oral Lamivudine in Human Immunodeficiency Virus-Infected Children
Authors: Mueller Brigitta U. , Lewis Linda L. , Yuen Geoffrey J. , Farley Maureen , Keller Amy , Church Joseph A. , Goldsmith Jonathan C. , Venzon David J. , Rubin Marc , Pizzo Philip A. , Balis Frank M.
Published: October 2018

We studied the pharmacokinetics of intravenously and orally administered lamivudine at six dose levels ranging from 0.5 to 10 mg/kg of body weight in 52 children with human immunodeficiency virus infection. A two-compartment model with first-order elimination from the central compartment was simultaneously fitted to the serum drug concentration-time data obtained after intravenous and oral administration. The maximal concentration at the end of the 1-h intravenous infusion and the area under the concentration-time curve after oral and intravenous administration increased proportionally with the dose. The mean clearance of lamivudine (± standard deviation) in the children was 0.53 ± 0.19 liter/kg/h (229 ± 77 ml/min/m
2
of body surface area), and the mean half-lives at the distribution and elimination phases were 0.23 ± 0.18 and 2.2 ± 2.1 h, respectively. Clearance was age dependent when normalized to body weight but age independent when normalized to body surface area. Lamivudine was rapidly absorbed after oral administration, and 66% ± 25% of the oral dose was absorbed. Serum lamivudine concentrations were maintained above 1 μM for ≥8 h of 24 h on the twice daily oral dosing schedule with doses of ≥2 mg/kg. The cerebrospinal fluid drug concentration measured 2 to 4 h after the dose was 12% (range, 0 to 46%) of the simultaneously measured serum drug concentration. A limited-sampling strategy was developed to estimate the area under the concentration-time curve for concentrations in serum at 2 and 6 h.
Bacteriological Efficacies of Three Macrolides Compared with Those of Amoxicillin-Clavulanate against
Streptococcus pneumoniae
and
Haemophilus influenzae
Authors: Berry Valerie , Thorburn Christine E. , Knott Sarah J. , Woodnutt Gary
Published: October 2018

Comparative antibacterial efficacies of erythromycin, clarithromycin, and azithromycin were examined against
Streptococcus pneumoniae
and
Haemophilus influenzae
, with amoxicillin-clavulanate used as the active control. In vitro, the macrolides at twice their MICs and at concentrations achieved in humans were bacteriostatic or reduced the numbers of viable
S. pneumoniae
slowly, whereas amoxicillin-clavulanate showed a rapid antibacterial effect. Against
H. influenzae
, erythromycin, clarithromycin, and clarithromycin plus 14-hydroxy clarithromycin at twice their MICs produced a slow reduction in bacterial numbers, whereas azithromycin was bactericidal. Azithromycin at the concentrations achieved in the serum of humans was bacteriostatic, whereas erythromycin and clarithromycin were ineffective. In experimental respiratory tract infections in rats, clarithromycin (equivalent to 250 mg twice daily [b.i.d.]) and amoxicillin-clavulanate (equivalent to 500 plus 125 mg b.i.d., respectively) were highly effective against
S. pneumoniae
, but azithromycin (equivalent to 500 and 250 mg once daily) was significantly less effective (
P
< 0.01). Against
H. influenzae
, clarithromycin treatment (equivalent to 250 or 500 mg b.i.d.) was similar to no treatment and was significantly less effective than amoxicillin-clavulanate treatment (
P
< 0.01). Azithromycin demonstrated significant in vivo activity (
P
< 0.05) but was significantly less effective than amoxicillin-clavulanate (
P
< 0.05). Overall, amoxicillin-clavulanate was effective in vitro and in vivo. Clarithromycin and erythromycin were ineffective in vitro and in vivo against
H. influenzae
, and azithromycin (at concentrations achieved in humans) showed unreliable activity against both pathogens. These results may have clinical implications for the utility of macrolides in the empiric therapy of respiratory tract infections.
In Vitro Inhibition of Hepadnavirus Polymerases by the Triphosphates of BMS-200475 and Lobucavir
Authors: Seifer Maria , Hamatake Robert K. , Colonno Richard J. , Standring David N.
Published: October 2018

The guanosine analogs BMS-200475 and lobucavir have previously been shown to effectively suppress propagation of the human hepatitis B virus (HBV) and woodchuck hepatitis virus (WHV) in 2.2.15 liver cells and in the woodchuck animal model system, respectively. This repression was presumed to occur via inhibition of the viral polymerase (Pol) by the triphosphate (TP) forms of BMS-200475 and lobucavir which are both produced in mammalian cells. To determine the exact mode of action, BMS-200475–TP and lobucavir-TP, along with several other guanosine analog-TPs and lamivudine-TP were tested against the HBV, WHV, and duck hepatitis B virus (DHBV) polymerases in vitro. Estimates of the 50% inhibitory concentrations revealed that BMS-200475–TP and lobucavir-TP inhibited HBV, WHV, and DHBV Pol comparably and were superior to the other nucleoside-TPs tested. More importantly, both analogs blocked the three distinct phases of hepadnaviral replication: priming, reverse transcription, and DNA-dependent DNA synthesis. These data suggest that the modest potency of lobucavir in 2.2.15 cells may be the result of poor phosphorylation in vivo. Kinetic studies revealed that BMS-200475–TP and lobucavir-TP competitively inhibit HBV Pol and WHV Pol with respect to the natural dGTP substrate and that both drugs appear to bind to Pol with very high affinities. Endogenous sequencing reactions conducted in replicative HBV nucleocapsids suggested that BMS-200475–TP and lobucavir-TP are nonobligate chain terminators that stall Pol at sites that are distinct yet characteristically two to three residues downstream from dG incorporation sites.