bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vitro Activities of Voriconazole (UK-109,496) and Four Other Antifungal Agents against 394 Clinical Isolates of
Candida
spp
Authors: Marco F. , Pfaller M. A. , Messer S. , Jones R. N.
Published: October 2018

Voriconazole (formerly UK-109,496) is a new monotriazole antifungal agent which has potent activity against
Candida
,
Cryptococcus
, and
Aspergillus
species. We investigated the in vitro activity of voriconazole compared to those of fluconazole, itraconazole, amphotericin B, and flucytosine (5FC) against 394 bloodstream isolates of
Candida
(five species) obtained from more than 30 different medical centers. MICs of all antifungal drugs were determined by the method recommended by the National Committee for Clinical Laboratory Standards using RPMI 1640 test medium. Overall, voriconazole was quite active against all the yeast isolates (MIC at which 90% of the isolates are inhibited [MIC
90
], ≤0.5 μg/ml).
Candida albicans
was the most susceptible species (MIC
90
, 0.06 μg/ml) and
Candida glabrata
and
Candida krusei
were the least (MIC
90
, 1 μg/ml). Voriconazole was more active than amphotericin B and 5FC against all species except
C. glabrata
and was also more active than itraconazole and fluconazole. For isolates of
Candida
spp. with decreased susceptibility to fluconazole and itraconazole MICs of voriconazole were also higher. Based on these results, voriconazole has promising antifungal activity and further in vitro and in vivo investigations are warranted.
Granulocyte Colony-Stimulating Factor and Azole Antifungal Therapy in Murine Aspergillosis: Role of Immune Suppression
Authors: Graybill John R. , Bocanegra Rosie , Najvar Laura K. , Loebenberg David , Luther Mike F.
Published: October 2018

Outbred ICR mice were immune suppressed either with hydrocortisone or with 5-fluorouracil and were infected intranasally with
Aspergillus fumigatus
. Beginning 3 days before infection some groups of mice were given recombinant human granulocyte colony-stimulating factor (G-CSF), SCH56592 (an antifungal triazole), or both. Corticosteroid-pretreated mice responded to SCH56592 and had reduced counts in lung tissue and prolonged survival. In these mice, G-CSF strongly antagonized the antifungal activity of SCH56592. Animals treated with both agents developed large lung abscesses with polymorphonuclear leukocytes and large amounts of
Aspergillus
. In contrast, mice made neutropenic with 5-fluorouracil and then infected with
A. fumigatus
conidia benefited from either G-CSF or triazoles, and the effect of the combination was additive rather than antagonistic. Host predisposing factors contribute in different ways to the outcome of growth factor therapy in aspergillosis.
In Vitro and In Vivo Efficacy of the Triazole TAK-187 against
Cryptococcus neoformans
Authors: Schell Wiley A. , De Almeida Gisele Madeira Duboc , Dodge Richard K. , Okonogi Kenji , Perfect John R.
Published: October 2018

Multiple isolates of
Cryptococcus neoformans
, including those with fluconazole resistance, were tested to assess the in vitro activity of the new triazole TAK-187. MICs of TAK-187 were at least eightfold lower than those of fluconazole, and fungicidal concentrations for most isolates were 4 μg/ml or less. TAK-187 also was evaluated as intermittent therapy using two dosages in a rabbit model of experimental cryptococcal meningitis. Compared to daily treatment with fluconazole, as little as two doses of TAK-187 given 7 days apart were found to be effective. Plasma and cerebrospinal fluid TAK-187 concentrations were many times higher than MICs and fungicidal concentrations. Based upon its therapeutic efficacy and long half-life in the rabbit model, TAK-187 should be investigated for intermittent dosing in treatment or suppression of cryptococcal infections in humans.
gyrA
Mutations Associated with Fluoroquinolone Resistance in Eight Species of
Enterobacteriaceae
Authors: Weigel Linda M. , Steward Christine D. , Tenover Fred C.
Published: October 2018

Fluoroquinolone resistance (FQ-R) in clinical isolates of
Enterobacteriaceae
species has been reported with increasing frequency in recent years. Two mechanisms of FQ-R have been identified in gram-negative organisms: mutations in DNA gyrase and reduced intracellular drug accumulation. A single point mutation in
gyrA
has been shown to reduce susceptibility to fluoroquinolones. To determine the extent of
gyrA
mutations associated with FQ-R in enteric bacteria, one set of oligonucleotide primers was selected from conserved sequences in the flanking regions of the quinolone resistance-determining regions (QRDR) of
Escherichia coli
and
Klebsiella pneumoniae
. This set of primers was used to amplify and sequence the QRDRs from 8
Enterobacteriaceae
type strains and 60 fluoroquinolone-resistant clinical isolates of
Citrobacter freundii
,
Enterobacter aerogenes
,
Enterobacter cloacae
,
E. coli
,
K. pneumoniae
,
Klebsiella oxytoca
,
Providencia stuartii
, and
Serratia marcescens
. Although similarity of the nucleotide sequences of seven species ranged from 80.8 to 93.3%, when compared with that of
E. coli
, the amino acid sequences of the
gyrA
QRDR were highly conserved. Conservative amino acid substitutions were detected in the QRDRs of the susceptible type strains of
C. freundii
,
E. aerogenes
,
K. oxytoca
(Ser-83 to Thr), and
P. stuartii
(Asp-87 to Glu). Strains with ciprofloxacin MICs of >2 μg/ml expressed amino acid substitutions primarily at the Gly-81, Ser-83, or Asp-87 position. Fluoroquinolone MICs varied significantly for strains exhibiting identical
gyrA
mutations, indicating that alterations outside
gyrA
contribute to resistance. The type and position of amino acid alterations also differed among these six genera. High-level FQ-R frequently was associated with single
gyrA
mutations in all species of
Enterobacteriaceae
in this study except
E. coli.
In Vitro Studies of Pharmacodynamic Properties of Vancomycin against
Staphylococcus aureus
and
Staphylococcus epidermidis
Authors: Löwdin E. , Odenholt I. , Cars O.
Published: October 2018

The bactericidal activities of vancomycin against two reference strains and two clinical isolates of
Staphylococcus aureus
and
Staphylococcus epidermidis
were studied with five different concentrations ranging from 2× to 64× the MIC. The decrease in the numbers of CFU at 24 h was at least 3 log
10
CFU/ml for all strains. No concentration-dependent killing was observed. The postantibiotic effect (PAE) was determined by obtaining viable counts for two of the reference strains, and the viable counts varied markedly: 1.2 h for
S. aureus
and 6.0 h for
S. epidermidis
. The determinations of the PAE, the postantibiotic sub-MIC effect (PA SME), and the sub-MIC effect (SME) for all strains were done with BioScreen C, a computerized incubator for bacteria. The PA SMEs were longer than the SMEs for all strains tested. A newly developed in vitro kinetic model was used to expose the bacteria to continuously decreasing concentrations of vancomycin. A filter prevented the loss of bacteria during the experiments. One reference strain each of
S. aureus
and
S. epidermidis
and two clinical isolates of
S. aureus
were exposed to an initial concentration of 10× the MIC of vancomycin with two different half-lives (
t
1/2
s): 1 or 5 h. The post-MIC effect (PME) was calculated as the difference in time for the bacteria to grow 1 log
10
CFU/ml from the numbers of CFU obtained at the time when the MIC was reached and the corresponding time for an unexposed control culture. The difference in PME between the strains was not as pronounced as that for the PAE. Furthermore, the PME was shorter when a
t
1/2
of 5 h (approximate terminal
t
1/2
in humans) was used. The PMEs at
t
1/2
s of 1 and 5 h were 6.5 and 3.6 h, respectively, for
S. aureus
. The corresponding figures for
S. epidermidis
were 10.3 and less than 6 h. The shorter PMEs achieved with a
t
1/2
of 5 h and the lack of concentration-dependent killing indicate that the time above the MIC is the parameter most important for the efficacy of vancomycin.
In Vitro Activities of 15 Antimicrobial Agents against Clinical Isolates of South African Enterococci
Authors: Struwig M. C. , Botha P. L. , Chalkley L. J.
Published: October 2018

The activities of a panel of currently available antibiotics and the investigational agents LY 333328, linezolid, CL 331,002, CL 329,998, moxifloxacin (BAY 12-8039), trovafloxacin, and quinupristin-dalfopristin against 274 clinical isolates of enterococci were determined. No vancomycin resistance or β-lactamase production was observed. Except for 12 isolates (all non-
Enterococcus faecalis
) showing reduced susceptibility to quinupristin-dalfopristin (MIC, ≥4 μg/ml), the new agents exhibited promising in vitro antienterococcal activity.
MIC-Based Interspecies Prediction of the Antimicrobial Effects of Ciprofloxacin on Bacteria of Different Susceptibilities in an In Vitro Dynamic Model
Authors: Firsov Alexander A. , Vostrov Sergey N. , Shevchenko Alexander A. , Zinner Stephen H. , Cornaglia Giuseppe , Portnoy Yury A.
Published: October 2018

Multiple predictors of fluoroquinolone antimicrobial effects (AMEs) are not usually examined simultaneously in most studies. To compare the predictive potentials of the area under the concentration-time curve (AUC)-to-MIC ratio (AUC/MIC), the AUC above MIC (AUC
eff
), and the time above MIC (
T
eff
), the kinetics of killing and regrowth of four bacterial strains exposed to monoexponentially decreasing concentrations of ciprofloxacin were studied in an in vitro dynamic model. The MICs of ciprofloxacin for clinical isolates of
Staphylococcus aureus
,
Escherichia coli
11775 (I) and 204 (II), and
Pseudomonas aeruginosa
were 0.6, 0.013, 0.08, and 0.15 μg/ml, respectively. The simulated values of AUC were designed to provide similar 1,000-fold (
S. aureus
,
E. coli
I, and
P. aeruginosa
) or 2,000-fold (
E. coli
II) ranges of the AUC/MIC. In each case except for the highest AUC/MIC ratio, the observation periods included complete regrowth in the time-kill curve studies. The AME was expressed by its intensity,
I
E
(the area between the control growth and time-kill and regrowth curves up to the point where the viable counts of regrowing bacteria are close to the maximum values observed without drug). For most AUC ranges the
I
E
-AUC curves were fitted by an
E
max
(maximal effect) model, whereas the effects observed at very high AUCs were greater than those predicted by the model. The AUCs that produced 50% of maximal AME were proportional to the MICs for the strains studied, but maximal AMEs (
I

E
max

) and the extent of sigmoidicity (
s
) were not related to the MIC. Both
T
eff
and log AUC/MIC correlated well with
I
E
(
r
2
= 0.98 in both cases) in a species-independent fashion. Unlike
T
eff
or log AUC/MIC, a specific relationship between
I
E
and log AUC
eff
was inherent in each strain. Although each
I
E
and log AUC
eff
plot was fitted by linear regression (
r
2
= 0.97 to 0.99), these plots were not superimposed and therefore are bacterial species dependent. Thus, AUC/MIC and
T
eff
were better predictors of ciprofloxacin’s AME than AUC
eff
. This study suggests that optimal predictors of the AME produced by a given quinolone (intraquinolone predictors) may be established by examining its AMEs against bacteria of different susceptibilities.
T
eff
was shown previously also to be the best interquinolone predictor, but unlike AUC/MIC, it cannot be used to compare different quinolones. AUC/MIC might be the best predictor of the AME in comparisons of different quinolones.
Effects of
Salmonella typhimurium
Infection and Ofloxacin Treatment on Glucose and Glutamine Metabolism in Caco-2/TC-7 Cells
Authors: Posho Leta , Delbos-Bocage Laurence , Gueylard Delphine , Farinotti Robert , Carbon Claude
Published: October 2018

The effects of both
Salmonella typhimurium
infection and 5 mM ofloxacin treatment on 2 mM glutamine and 5 mM glucose metabolism in the enterocyte-like Caco-2/TC-7 cell line were studied. These cells utilized glutamine (212.07 ± 16.75 [mean ± standard deviation] nmol per h per 10
6
viable cells) and, to a lesser extent, glucose (139.63 ± 11.52 nmol per h per 10
6
viable cells). Metabolism of these substrates in Caco-2/TC-7 cells resembled that in rat, pig, or human enterocytes. Infection by
S. typhimurium
C53-enhanced glucose and glutamine substrate utilization by 32 and 22%, respectively and enhanced glucose and glutamine substrate oxidation by eight- and twofold, respectively. These increases in glucose and glutamine metabolism (especially glucose metabolism) were due in part to the metabolism of intracellular bacteria and/or to the activation of cellular metabolism. Substrate metabolism (especially glucose metabolism) in C53-infected cells was partially reduced by treatment with ofloxacin. It was concluded that cellular fuel metabolism is stimulated at the earliest stage of infection (3 to 4 h) and that treatment with 5 mM ofloxacin does not completely restore substrate metabolism to the levels observed in uninfected cells, possibly because this treatment does not eradicate intracellular
S. typhimurium
completely.
Central Role of Hemoglobin Degradation in Mechanisms of Action of 4-Aminoquinolines, Quinoline Methanols, and Phenanthrene Methanols
Authors: Mungthin Mathirut , Bray Patrick G. , Ridley Robert G. , Ward Stephen A.
Published: October 2018

We have used a specific inhibitor of the malarial aspartic proteinase plasmepsin I and a nonspecific cysteine proteinase inhibitor to investigate the importance of hemoglobin degradation in the mechanism of action of chloroquine, amodiaquine, quinine, mefloquine (MQ), halofantrine, and primaquine. Both proteinase inhibitors antagonized the antiparasitic activity of all drugs tested with the exception of primaquine. An inhibitor of plasmepsin I, Ro40-4388, reduced the incorporation of radiolabelled chloroquine and quinine into malarial pigment by 95%, while causing a 70% reduction in the incorporation of radiolabelled MQ. Cysteine proteinase inhibitor E64 reduced the incorporation of chloroquine and quinine into malarial pigment by 60 and 40%, respectively. This study provides definitive support for the central role of hemoglobin degradation in the mechanism of action of the 4-aminoquinolines and the quinoline and phenanthrene methanol antimalarials.
Quinolone Resistance Mutations in the GrlB Protein of
Staphylococcus aureus
Authors: Tanaka Mayumi , Onodera Yoshikuni , Uchida Yoko , Sato Kenichi
Published: October 2018

Two altered GrlB proteins (one with an Asp-432→Asn alteration and one with an Asn-470→Asp alteration) of
Staphylococcus aureus
were purified as fusion proteins to maltose-binding protein. The 50% inhibitory concentrations of levofloxacin were 14 and 3.4 μg/ml against topoisomerase IV containing GrlB proteins with alterations at positions 432 and 470, respectively. These results suggest that the alteration of Asp to Asn at position 432 may be responsible for quinolone resistance.
Outbreak of Ceftazidime-Resistant
Klebsiella pneumoniae
in a Pediatric Hospital in Warsaw, Poland: Clonal Spread of the TEM-47 Extended-Spectrum β-Lactamase (ESBL)-Producing Strain and Transfer of a Plasmid Carrying the SHV-5-Like ESBL-Encoding Gene
Authors: Gniadkowski Marek , Pałucha Andrzej , Grzesiowski Paweł , Hryniewicz Waleria
Published: October 2018

In 1996 a large, 300-bed pediatric hospital in Warsaw, Poland, started a program of monitoring infections caused by extended-spectrum β-lactamase (ESBL)-producing microorganisms. Over the first 3-month period eight
Klebsiella pneumoniae
isolates were identified as being resistant to ceftazidime. Six of these were found to produce the TEM-47 ESBL, which we first described in a
K. pneumoniae
strain recovered a year before in a pediatric hospital in Łódź, Poland, which is 140 km from Warsaw. Typing results revealed a very close relatedness among all these isolates, which suggested that the clonal outbreak in Warsaw was caused by a strain possibly imported from Łódź. The remaining two isolates expressed the SHV-5-like ESBL, which resulted from the horizontal transfer of a plasmid carrying the
bla
SHV
gene between nonrelated strains. The data presented here exemplify the complexity of the epidemiological situation concerning ESBL producers typical for large Polish hospitals, in which no ESBL-monitoring programs were in place prior to 1995.
Ambulatory Treatment of Multidrug-Resistant
Staphylococcus
-Infected Orthopedic Implants with High-Dose Oral Co-trimoxazole (Trimethoprim-Sulfamethoxazole)
Authors: Stein Andreas , Bataille Jean Francois , Drancourt Michel , Curvale Georges , Argenson Jean Noel , Groulier Pierre , Raoult Didier
Published: October 2018

We examined the effectiveness and safety of high-dose oral co-trimoxazole (trimethoprim-sulfamethoxazole) for the treatment of orthopedic implants infected with multidrug-resistant
Staphylococcus
species. The prospective study was conducted between 1989 and 1997 in a university medical center with ambulatory-care services. Patients eligible for the study consisted of those from whom multidrug-resistant
Staphylococcus
spp. organisms susceptible only to glycopeptides and co-trimoxazole were isolated from their orthopedic implants and for whom there was no contraindication to the treatment. All patients were treated orally with high-dose co-trimoxazole (trimethoprim, 20 mg/kg of body weight/day; sulfamethoxazole, 100 mg/kg/day). Patients with prosthetic hip infections were treated for 6 months, with removal of any unstable prosthesis after 5 months of treatment; patients with prosthetic knee infections were treated for 9 months, with removal of any unstable prosthesis after 6 months of treatment; and patients with infected osteosynthetic devices were treated for 6 months, with removal of the device after 3 months of treatment, if necessary. Monthly clinical evaluations were conducted until the completion of the treatment, and follow-up examinations were conducted regularly for up to 6 years. The overall treatment success rate was 66.7% (26 of 39 patients), with success rates of 62.5% for patients with prosthetic knee infections, 50% for those with prosthetic hip infections, and 78.9% for those with other device infections. Seventeen of the 28 (60.7%) patients who did not have any orthopedic material removed were cured. Eight patients stopped the treatment because of side effects, and one patient was not compliant. In three patients treatment failed because of the appearance of a resistant bacterium. Long-term oral ambulatory treatment with co-trimoxazole appears to be an effective alternative to the conventional medicosurgical treatment of chronic multidrug-resistant
Staphylococcus
-infected orthopedic implants which includes long-term intravenous antibiotic therapy combined with surgical debridement and removal of foreign material or its subsequent one- or two-stage replacement.
Efficacious Topical Treatment for Murine Cutaneous Leishmaniasis with Ethanolic Formulations of Amphotericin B
Authors: Frankenburg Shoshana , Glick Dvora , Klaus Sidney , Barenholz Yechezkel
Published: October 2018

The goal of the present study was to evaluate the antileishmanial effects of topically applied lipid-based formulations containing amphotericin B (AmB) in CBA mice as a model for human cutaneous leishmaniasis. Such treatment, if efficacious, is expected to be superior to systemic treatments since, by acting in a localized manner, it will require lower, and therefore less toxic, drug dosages. Three preparations of AmB complexed to polar lipids were tested: Fungizone (mixed micelles composed of AmB and deoxycholate), Amphocil (AmB and cholesteryl sulfate complex), and ABPLC (AmB and phospholipid complex). All these formulations killed parasites in vitro with similar efficacies but were ineffective when they were applied topically. However, Amphocil and ABPLC, but not Fungizone, when dispersed in an aqueous solution containing 5 to 25% ethanol, induced a statistically significant improvement in lesion size from week 2 or 3 onward (a total of 15 mg of AmB per kg of body weight was applied over 3 weeks). AmB biodistribution measurements following topical application of Amphocil, determined by high-pressure liquid chromatography, showed that AmB was detectable in the skin but not in the internal organs. Application of at least 10 times more drug was necessary to obtain detectable levels of AmB in the internal organs. After application of therapeutic doses of ABPLC, very low levels of AmB were detected in the internal organs. These experiments show for the first time that AmB administered topically as a complex either with cholesteryl sulfate or with phospholipids and in the presence of ethanol can penetrate the skin and kill sensitive organisms in a localized manner by using very low total drug concentrations.
Possible Mechanism by Which the Carbapenem Antibiotic Panipenem Decreases the Concentration of Valproic Acid in Plasma in Rats
Authors: Kojima Saori , Nadai Masayuki , Kitaichi Kiyoyuki , Wang Li , Nabeshima Toshitaka , Hasegawa Takaaki
Published: October 2018

There is evidence indicating that the carbapenem antibiotic panipenem decreases plasma concentrations of valproic acid (VPA) in epileptic patients during VPA therapy. The mechanism for panipenem-induced changes in the pharmacokinetics of VPA was investigated in rats with and without bile duct cannulation. The effect of panipenem on the pharmacokinetics of diclofenac, which undergoes extensive enterohepatic recirculation, was also examined. VPA (50 mg/kg of body weight) or diclofenac (10 mg/kg of body weight) was administered intravenously under the steady-state plasma panipenem concentration of 4 μg/ml, which had been achieved by a constant infusion rate. Panipenem decreased the plasma VPA concentrations in rats without bile duct cannulation but did not change the volume of the initial space and protein binding of VPA. However, panipenem had no effect on the plasma VPA concentrations and the biliary excretion of VPA in rats with bile duct cannulation. The secondary increase in plasma diclofenac concentration observed in the absence of panipenem was diminished in the presence of panipenem. These findings suggest that panipenem decreases plasma VPA concentrations by suppressing its enterohepatic recirculation, probably due to a panipenem-induced decrease in the numbers of enteric bacteria.
In Vitro Resistance to Thrombin-Induced Platelet Microbicidal Protein among Clinical Bacteremic Isolates of
Staphylococcus aureus
Correlates with an Endovascular Infectious Source
Authors: Bayer Arnold S. , Cheng Darwin , Yeaman Michael R. , Corey G. Ralph , McClelland R. Scott , Harrel Lizzie J. , Fowler Vance G.
Published: October 2018

Platelet microbicidal proteins (PMPs), small cationic peptides released at sites of endovascular damage, kill common bloodstream pathogens in vitro. Our group previously showed that in vitro resistance of clinical staphylococcal and viridans group streptococcal bacteremic strains to PMPs correlated with the diagnosis of infective endocarditis (IE) (Wu et al., Antimicrob. Agents Chemother. 38:729–732, 1994). However, that study was limited by (i) the small number of
Staphylococcus aureus
isolates from IE patients, (ii) the retrospective nature of the case definitions, and (iii) the diverse geographic sources of strains. The present study evaluated the in vitro PMP susceptibility phenotype of a large number of staphylococcemic isolates (
n
= 60), collected at a single medical center and categorized by defined and validated clinical criteria. A significantly higher proportion of staphylococcemic strains from patients with IE was PMP resistant in vitro than the proportion of strains from patients with soft tissue sepsis (83% and 33%, respectively;
P
< 0.01). Moreover, the levels of PMP resistance (mean percent survival of strains after 2-h exposure to PMP in vitro) were significantly higher for isolates from patients with IE and with vascular catheter sepsis than for strains from patients with abscess sepsis (
P
< 0.005 and
P
< 0.01, respectively). These data further support the concept that bloodstream pathogens that exhibit innate or acquired PMP resistance have a survival advantage with respect to either the induction or progression of endovascular infections.
In Vitro Activities of Membrane-Active Peptides against Gram-Positive and Gram-Negative Aerobic Bacteria
Authors: Giacometti A. , Cirioni O. , Greganti G. , Quarta M. , Scalise G.
Published: October 2018

Four peptides, cecropin P1, magainin II, indolicidin, and ranalexin, were evaluated against 202 clinical isolates of gram-positive and gram-negative aerobic bacteria by a microbroth dilution method. The gram-negative isolates were more susceptible to cecropin P1. Ranalexin was the most active compound against the gram-positive strains. The bactericidal activity of each peptide was equivalent to, or 1 dilution above, the MIC. In conclusion, the four peptides exhibited different in vitro activities and rapid time-dependent killing.
Inhibition of Acute-, Latent-, and Chronic-Phase Human Immunodeficiency Virus Type 1 (HIV-1) Replication by a Bistriazoloacridone Analog That Selectively Inhibits HIV-1 Transcription
Authors: Turpin Jim A. , Buckheit Robert W. , Derse David , Hollingshead Melinda , Williamson Karen , Palamone Carla , Osterling M. Clayton , Hill Shawn A. , Graham Lisa , Schaeffer Catherine A. , Bu Ming , Huang Mingjun , Cholody Wieslaw M. , Michejda Christopher J. , Rice William G.
Published: October 2018

Nanomolar concentrations of temacrazine (1,4-bis[3-(6-oxo-6H-v-triazolo[4,5,1-de]acridin-5-yl)amino-propyl]piperazine) were discovered to inhibit acute human immunodeficiency virus type 1 (HIV-1) infections and suppress the production of virus from chronically and latently infected cells containing integrated proviral DNA. This bistriazoloacridone derivative exerted its mechanism of antiviral action through selective inhibition of HIV-1 transcription during the postintegrative phase of virus replication. Mechanistic studies revealed that temacrazine blocked HIV-1 RNA formation without interference with the transcription of cellular genes or with events associated with the HIV-1 Tat and Rev regulatory proteins. Although temacrazine inhibited the in vitro 3′ processing and strand transfer activities of HIV-1 integrase, with a 50% inhibitory concentration of approximately 50 nM, no evidence of an inhibitory effect on the intracellular integration of proviral DNA into the cellular genome during the early phase of infection could be detected. Furthermore, temacrazine did not interfere with virus attachment or fusion to host cells or the enzymatic activities of HIV-1 reverse transcriptase or protease, and the compound was not directly virucidal. Demonstration of in vivo anti-HIV-1 activity by temacrazine identifies bistriazoloacridones as a new class of pharmaceuticals that selectively blocks HIV-1 transcription.
Prophylactic Anti-Infective Activity of Poly-[1-6]-β-d-Glucopyranosyl-[1-3]-β-d-Glucopyranose Glucan in a Guinea Pig Model of Staphylococcal Wound Infection
Authors: Kernodle Douglas S. , Gates Hiriam , Kaiser Allen B.
Published: October 2018

The judicious use of perioperative antibiotic prophylaxis reduces the infectious complications of surgery. However, increased bacterial resistance within hospitals may make antibiotic prophylaxis less effective in the future and alternative strategies are needed. New immunomodulatory agents might prevent wound infections by stimulation of the host immune system. To test this hypothesis, we administered poly-[1-6]-β-d-glucopyranosyl-[1-3]-β-d-glucopyranose glucan (PGG glucan), which enhances neutrophil microbicidal activity, intravenously to guinea pigs in doses ranging from 0.015 to 4 mg/kg of body weight on the day before, on the day of, and on the day after intermuscular inoculation with methicillin-resistant strains ofStaphylococcus aureusandStaphylococcus epidermidis. Abscesses were identified at 72 h, and median infective doses (ID50) and statistical significance were determined by logistic regression. Guinea pigs receiving PGG glucan and inoculated with methicillin-resistantS. aureusandS. epidermidisexhibited ID50of as much as 2.5- and 60-fold higher, respectively, than those of control guinea pigs not receiving PGG glucan. Maximal protection was observed with a dose of 1 mg of PGG glucan per kg, and efficacy was reduced at higher as well as at lower PGG glucan doses. Furthermore, a single dose of PGG glucan given 24 h following bacterial inoculation was found to be effective in preventing infection. We conclude that PGG glucan reduces the risk of staphylococcal abscess formation. Neutrophil-activating agents are a novel means of prophylaxis against surgical infection and may be less likely than antibiotics to be affected adversely by the increasing antibiotic resistance of nosocomial pathogens.
Treatment of Invasive Fungal Infections in Renally Impaired Patients with Amphotericin B Colloidal Dispersion
Authors: Anaissie Elias J. , Mattiuzzi Gloria N. , Miller Carole B. , Noskin Gary A. , Gurwith Marc J. , Mamelok Richard D. , Pietrelli Larry A.
Published: October 2018

Amphotericin B colloidal dispersion (ABCD) is a new formulation of conventional amphotericin B designed to minimize drug distribution in the kidney and reduce nephrotoxicity. We studied the safety and efficacy of ABCD in 133 renally compromised patients with invasive fungal infections. Patients had either nephrotoxicity from amphotericin B or preexisting renal disease. Intravenous treatment with ABCD (4 mg/kg of body weight daily) was administered for up to 6 weeks. Evaluations included clinical response to treatment and adverse events, with emphasis on changes in serum creatinine levels. ABCD did not appear to have an adverse effect on renal function: mean serum creatinine level tended to decrease slightly with days on therapy, and increases were not dose related. Complete or partial response to treatment was reported for 50% of the 133 intent-to-treat patients and 67% of the 58 evaluable patients.
1,1,3-Trioxo-2
H
,4
H
-Thieno[3,4-
e
][1,2,4]Thiadiazine (TTD) Derivatives: a New Class of Nonnucleoside Human Immunodeficiency Virus Type 1 (HIV-1) Reverse Transcriptase Inhibitors with Anti-HIV-1 Activity
Authors: Witvrouw M. , Arranz M. E. , Pannecouque C. , Declercq R. , Jonckheere H. , Schmit J.-C. , Vandamme A.-M. , Diaz J. A. , Ingate S. T. , Desmyter J. , Esnouf R. , Van Meervelt L. , Vega S. , Balzarini J. , De Clercq E.
Published: October 2018

We report the development of a new group of nonnucleoside reverse transcriptase inhibitors (NNRTIs). One of the most active congeners of this series of 1,1,3-trioxo-2
H
,4
H
-thieno[3,4-
e
][1,2,4]thiadiazine (TTD) derivatives, i.e., 2-(3-fluorobenzyl)-4-cyanomethylen-1,1,3-trioxo-2
H
,4
H
-thieno[3,4-
e
][1,2,4]thiadiazine) (QM96639) was found to inhibit human immunodeficiency virus (HIV) type 1 [HIV-1 (III
B
)] replication in MT-4 cells at a concentration of 0.09 μM. This compound was toxic for the host cells only at a 1,400-fold higher concentration. The TTD derivatives proved effective against a variety of HIV-1 strains, including those that are resistant to 3′-azido-3′-deoxythymidine (AZT), but not against HIV-2 (ROD) or simian immunodeficiency virus (SIV/MAC251). HIV-1 strains containing the L100I, K103N, V106A, E138K, Y181C, or Y188H mutations in their reverse transcriptase (RT) displayed reduced sensitivity to the compounds. Their cross-resistance patterns correlated with that of nevirapine. 2-Benzyl-4-cyanomethylen-1,1,3-trioxo-2
H
,4
H
-thieno[3,4-
e
][1,2,4]thiadiazine (QM96521) enhanced the anti-HIV-1 activity of AZT and didanosine in a subsynergistic manner. HIV-1-resistant virus containing the V179D mutation in the RT was selected after approximately six passages of HIV-1 (III
B
) in CEM cells in the presence of different concentrations of QM96521. From structure-activity relationship analysis of a wide variety of TTD derivatives, a number of restrictions appeared as to the chemical modifications that were compatible with anti-HIV activity. Modelling studies suggest that in contrast to most other NNRTIs, but akin to nevirapine, QM96521 does not act as a hydrogen bond donor in the RT-drug complex.
Identification of GS 4104 as an Orally Bioavailable Prodrug of the Influenza Virus Neuraminidase Inhibitor GS 4071
Authors: Li Weixing , Escarpe Paul A. , Eisenberg Eugene J. , Cundy Kenneth C. , Sweet Clive , Jakeman Kenneth J. , Merson James , Lew Willard , Williams Matt , Zhang Lijun , Kim Choung U. , Bischofberger Norbert , Chen Ming S. , Mendel Dirk B.
Published: October 2018

GS 4071 is a potent carbocyclic transition-state analog inhibitor of influenza virus neuraminidase with activity against both influenza A and B viruses in vitro. GS 4116, the guanidino analog of GS 4071, is a 10-fold more potent inhibitor of influenza virus replication in tissue culture than GS 4071. In this study we determined the oral bioavailabilities of GS 4071, GS 4116, and their respective ethyl ester prodrugs in rats. Both parent compounds and the prodrug of the guanidino analog exhibited poor oral bioavailability (2 to 4%) and low peak concentrations in plasma (
C
max
s;
C
max
<0.06 μg/ml). In contrast, GS 4104, the ethyl ester prodrug of GS 4071, exhibited good oral bioavailability (35%) as GS 4071 and high
C
max
s of GS 4071 (C
max
= 0.47 μg/ml) which are 150 times the concentration necessary to inhibit influenza virus neuraminidase activity by 90%. The bioavailability of GS 4104 as GS 4071 was also determined in mice (30%), ferrets (11%), and dogs (73%). The plasma of all four species exhibited high, sustained concentrations of GS 4071 such that at 12 h postdosing the concentrations of GS 4071 in plasma exceeded those necessary to inhibit influenza virus neuraminidase activity by 90%. These results demonstrate that GS 4104 is an orally bioavailable prodrug of GS 4071 in animals and that it has the potential to be an oral agent for the prevention and treatment of influenza A and B virus infections in humans.
Neurotoxicodynamics of the Interaction between Ciprofloxacin and Foscarnet in Mice
Authors: Matsuo Hirotami , Ryu Miwako , Nagata Aya , Uchida Takahiro , Kawakami Jun-Ichi , Yamamoto Koujirou , Iga Tatsuji , Sawada Yasufumi
Published: October 2018

The potential for convulsions induced by the coadministration of ciprofloxacin (CPFX) and foscarnet (PFA) may be due not to a change in the distribution of CPFX to the brain but to a potential CPFX-induced inhibition of γ-aminobutyric acid (GABA)-GABA
A
receptor binding in the presence of PFA.
Antimicrobial Activity of Novel Furanonaphthoquinone Analogs
Authors: Nagata Kumiko , Hirai Kei-Ichi , Koyama Junko , Wada Yasunao , Tamura Toshihide
Published: October 2018

Analogs of furanonaphthoquinone (FNQ) from
Tecoma ipe
Mart had MICs ranging from 1.56 to 25 μg/ml against gram-positive bacteria. FNQ showed significantly lower MICs against methicillin-resistant
Staphylococcus aureus
than against methicillin-sensitive
S. aureus
. FNQ inhibited
Helicobacter pylori
with an MIC of 0.1 μg/ml. Fungi, including pathogenic species, were sensitive to FNQ with MICs similar to those of amphotericin B.
Thirteen-Year Evolution of Azole Resistance in Yeast Isolates and Prevalence of Resistant Strains Carried by Cancer Patients at a Large Medical Center
Authors: Boschman Cynthia R. , Bodnar Ulana R. , Tornatore Michelle A. , Obias Arlene A. , Noskin Gary A. , Englund Kristin , Postelnick Michael A. , Suriano Terra , Peterson Lance R.
Published: October 2018

Drug resistance is emerging in many important microbial pathogens, including
Candida albicans
. We performed fungal susceptibility tests with archived isolates obtained from 1984 through 1993 and fresh clinical isolates obtained from 1994 through 1997 by testing their susceptibilities to fluconazole, ketoconazole, and miconazole and compared the results to the rate of fluconazole use. All isolates recovered prior to 1993 were susceptible to fluconazole. Within 3 years of widespread azole use, we detected resistance to all agents in this class. In order to assess the current prevalence of resistant isolates in our hematologic malignancy and transplant patients, we obtained rectal swabs from hospitalized, non-AIDS, immunocompromised patients between June 1995 and January 1996. The swabs were inoculated onto sheep’s blood agar plates containing 10 μg of vancomycin and 20 μg of gentamicin/ml of agar. One hundred one yeasts were recovered from 97 patients and were tested for their susceptibilities to amphotericin B, fluconazole, flucytosine, ketoconazole, and miconazole. The susceptibility pattern was then compared to those for all clinical isolates obtained throughout the medical center. The antifungal drug histories for each patient were also assessed. The yeasts from this surveillance study were at least as susceptible as the overall hospital strains. There did not appear to be a direct linkage between prior receipt of antifungal agent therapy and carriage of a new, drug-resistant isolate. Increased resistance to newer antifungal agents has occurred at our medical center, but it is not focal to any high-risk patient population that we studied. Monitoring of susceptibility to antifungal agents appears to be necessary for optimizing clinical therapeutic decision making.
Survey of Resistance of Herpes Simplex Virus to Acyclovir in Northwest England
Authors: Christophers Jacqueline , Clayton Julie , Craske John , Ward Rosemary , Collins Peter , Trowbridge Martin , Darby Graham
Published: October 2018

Acyclovir (ACV) has been used for more than 15 years in the management of herpes simplex virus (HSV) and varicella-zoster virus (VZV) disease. The present survey was undertaken to assess the level of ACV resistance in the population. More than 2,000 HSV isolates from both immunocompetent and immunocompromised patients in northwest England were collected over a 2-year period and tested for sensitivity to ACV. These studies suggested a prevalence of resistance of approximately 0.1 to 0.6% in immunocompetent individuals, with no apparent difference in prevalence between treated and untreated groups. In line with previous studies, the prevalence of resistance in treated immunocompromised individuals was approximately 6%.
Efficacy of LY303366 against Amphotericin B-Susceptible and -Resistant
Aspergillus fumigatus
in a Murine Model of Invasive Aspergillosis
Authors: Verweij Paul E. , Oakley Karen L. , Morrissey Jacqui , Morrissey Graham , Denning David W.
Published: October 2018

LY303366 is a novel antifungal echinocandin with excellent in vitro activity against
Aspergillus
spp. We compared four doses (1, 2.5, 10, and 25 mg/kg of body weight) of LY303366 with amphotericin B (0.5 to 5 mg/kg) in a temporarily neutropenic murine model of invasive aspergillosis against an amphotericin B-susceptible (AF210) and an amphotericin B-resistant (AF65)
Aspergillus fumigatus
isolate based on in vivo response. Mice were immunosuppressed with cyclophosphamide (200 mg/kg) and infected 3 days later. Treatment started 18 h after infection and lasted for 10 days. LY303366 was given once daily intravenously for 10 days, and amphotericin B (at 0.5, 2, and 5 mg/kg) was given once daily intraperitoneally for 10 days, or only on days 1, 2, 4, and 7 (at 5 mg/kg). Kidneys and lungs from survivors were cultured on day 11. Control mice in both experiments had 90 to 100% mortality. Amphotericin B at 0.5 mg/kg and LY303366 at 1 mg/kg yielded 10 to 20% survival rates for mice infected with either AF210 or AF65. Amphotericin B at 2 and 5 (both regimens) mg/kg yielded a 70 to 100% survival rate for mice infected with AF210 but a 10 to 30% survival rate for mice infected with AF65 (
P
= 0.01 to 0.04 compared with AF210). Against AF210 and AF65, LY303366 at 2.5, 10, and 25 mg/kg produced a survival rate of 70 to 80%, which was as effective as amphotericin B for AF210, but superior to amphotericin B for AF65 (
P
< 0.03 to 0.0006). For AF65, LY303366 at 10 and 25 mg/kg/day was superior to amphotericin B at 2 and 5 mg/kg/day in reducing tissue colony counts (
P
= 0.01 to 0.003), and for AF210, amphotericin B at 5 mg/kg/day and at 5 mg/kg in four doses was more effective than all four regimens of LY303366 in reducing renal culture counts (
P
= 0.01 to 0.0001). The present study shows, for the first time, that in vivo resistance of
A. fumigatus
to amphotericin B exists, although this could not be detected by in vitro susceptibility assays. Furthermore, LY303366 appears to be effective against amphotericin B-susceptible and -resistant
A. fumigatus
infection in this model and should be further evaluated clinically.
Use of a Rapid Throughput In Vivo Screen To Investigate Inhibitors of Eukaryotic Topoisomerase II Enzymes
Authors: Hammonds Timothy R. , Maxwell Anthony , Jenkins John R.
Published: October 2018

Topoisomerase II catalyzes the passage of one DNA helix through another via a transient double-stranded break. The essential nature of this enzyme in cell proliferation and its mechanism of action make it an ideal target for cytotoxic agents.
Saccharomyces cerevisiae
topoisomerase II has been frequently used as a model for testing potential inhibitors of eukaryotic topoisomerase II as antitumor agents. The standard in vivo method of estimating the sensitivity of
S. cerevisiae
to the antitopoisomerase drugs is via inhibition or kill curves which rely on viable-cell counts and is labor intensive. We present an alternative to this, a high-throughput in vivo screen. This method makes use of a drug-permeable
S. cerevisiae
strain lacking endogenous topoisomerase II, which is modified to express either human topoisomerase IIα or IIβ or
S. cerevisiae
topoisomerase II carried on plasmids. Each modified strain expresses a full-length topoisomerase II enzyme, as opposed to the more commonly used temperature-sensitive
S. cerevisiae
mutant expressing yeast or yeast/human hybrid enzymes. A comparison of this new method with a plating-and-counting method gave similar drug sensitivity results, with increased accuracy and reduced manual input for the new method. The information generated has highlighted the sensitivities of different topoisomerase II enzymes and isoenzymes to several different classes of topoisomerase II inhibitor.
Increased Overall Antibiotic Susceptibility in
Staphylococcus aureus femAB
Null Mutants
Authors: Ling Baodong , Berger-Bächi Brigitte
Published: October 2018

The staphylococcal pentaglycine side chain of the peptidoglycan is reduced to one glycine in
femAB
null mutants. This is associated with increased susceptibility to methicillin and to a whole range of unrelated antibiotics as well. Genetic evidence suggests that
femAB
null mutants are only viable because of a compensatory mutation in an unlinked site.
Identification ofSaccharomyces cerevisiaeGenes Conferring Resistance to Quinoline Ring-Containing Antimalarial Drugs
Authors: Delling Ulrike , Raymond Martine , Schurr Erwin
Published: October 2018

To identify genes that can confer resistance to antimalarial drugs in yeast, we transformed the quinidine-sensitive strain CYX247-9A ofSaccharomyces cerevisiaewith a yeast genomic library and selected for transformants that grow in the presence of elevated levels of antimalarial drugs. Plasmids were rescued from such clones and were analyzed for the presence of individual open reading frames that can confer drug resistance. Using quinidine as the selective drug, we were able to identify three genes that can cause resistance to antimalarial drugs. Overexpression of the yeast genesCIN5(a member of the family of bZIP transcription factors),STI1(a Hsp90 cochaperone), andYOR273c(a member of the major facilitator superfamily of transmembrane transporters) conferred 3.9-, 7.0-, and 4.3-fold resistance to quinidine, respectively, over that of control yeast. Cross-resistance assays determined thatSTI1also conferred resistance to mefloquine (3.4-fold), whileCIN5also conferred resistance to mefloquine (9.6-fold) and chloroquine (5.4-fold). Using mefloquine as the selective drug, we determined that overexpression ofYBR233w, a member of the hnRNPK family of nuclear RNA binding proteins, conferred resistance to mefloquine (13.5-fold). Expression of the humanhnRNPKhomolog ofYBR233winS. cerevisiaealso conferred mefloquine resistance, suggesting that homologs of the identified resistance genes may perform similar functions in species other than yeast. Our experiments have identified heretofore unknown pathways of resistance to quinoline ring-containing antimalarial drugs inS. cerevisiae.
A237T as a Modulating Mutation in Naturally Occurring Extended-Spectrum TEM-Type β-Lactamases
Authors: Blázquez Jesús , Negri María-Cristina , Morosini María-Isabel , Gómez-Gómez J. M. , Baquero Fernando
Published: October 2018

A TEM-1 β-lactamase derivative containing the single amino acid substitution A237T slightly increased (from 24 to 32 μg/ml) the cephalothin MIC for
Escherichia coli
RYC1000 but did not influence the activities of cefotaxime, ceftazidime, and aztreonam (MICs of 0.03, 0.12, and 0.06 μg/ml, respectively). Despite its apparent neutrality, addition of the A237T mutation to the pair of mutations characterizing TEM-10 (R164S and E240K) had a strong effect on substrate preference. Ceftazidime and aztreonam MICs decreased from 128 and 16 μg/ml to 16 and 2 μg/ml, respectively. In contrast, the cefotaxime MIC increased from 0.5 to 4 μg/ml. The acquisition of apparently neutral or even deleterious mutations results in a very effective mechanism of resistance to different β-lactams that may be simultaneously or subsequently present in the environment. We propose here that the mutation in position 237 is an example of a modulating mutation and that consideration of this type of mutation may be important for understanding the evolution of β-lactamases.
Sulfonamide Resistance in
Streptococcus pyogenes
Is Associated with Differences in the Amino Acid Sequence of Its Chromosomal Dihydropteroate Synthase
Authors: Swedberg Göte , Ringertz Signe , Sköld Ola
Published: October 2018

Sulfonamide resistance in recent isolates of
Streptococcus pyogenes
was found to be associated with alterations of the chromosomally encoded dihydropteroate synthase (DHPS). There were 111 different nucleotides (13.8%) in the genes found in susceptible and resistant isolates, respectively, resulting in 30 amino acid changes (11.3%). These substantial changes suggested the possibility of a foreign origin of the resistance gene, in parallel to what has already been found for sulfonamide resistance in
Neisseria meningitidis
. The gene encoding DHPS was linked to at least three other genes encoding enzymes of the folate pathway. These genes were in the order GTP cyclohydrolase, dihydropteroate synthase, dihydroneopterin aldolase, and hydroxymethyldihydropterin pyrophosphokinase. The nucleotide differences in genes from resistant and susceptible strains extended from the beginning of the GTP cyclohydrolase gene to the end of the gene encoding DHPS, an additional indication for gene transfer in the development of resistance. Kinetic measurements established different affinities for sulfathiazole for DHPS enzymes isolated from resistant and susceptible strains.