bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Alterations in the Translational Attenuator of Constitutively Expressed
ermC
Genes
Authors: Werckenthin Christiane , Schwarz Stefan , Westh Henrik
Published: October 2018

Sequence deletions of 16, 59, and 111 bp as well as a tandem duplication of 272 bp with respect to the corresponding sequence of pT48 were identified in the regulatory regions of constitutively expressed
ermC
genes. Constitutive
ermC
gene expression as a consequence of these structural alterations is based on either the prevention of the formation of mRNA secondary structures in the translational attenuator or the preferential formation of those mRNA secondary structures which do not interfere with the translation of the
ermC
transcripts. A model for the development of sequence deletions in the
ermC
translational attenuator by homologous recombination is presented and experimentally tested by in vitro selection of constitutively expressed mutants in staphylococcal strains deficient and proficient in homologous recombination.
Purification, Reconstitution, and Inhibition of Cytochrome P-450 Sterol Δ
22
-Desaturase from the Pathogenic Fungus
Candida glabrata
Authors: Lamb David C. , Maspahy Segula , Kelly Diane E. , Manning Nigel J. , Geber Antonia , Bennett John E. , Kelly Steven L.
Published: October 2018

Sterol Δ
22
-desaturase has been purified from a strain of
Candida glabrata
with a disruption in the gene encoding sterol 14α-demethylase (cytochrome P-45051; CYP51). The purified cytochrome P-450 exhibited sterol Δ
22
-desaturase activity in a reconstituted system with NADPH–cytochrome P-450 reductase in dilaurylphosphatidylcholine, with the enzyme kinetic studies revealing a

K
m

for ergosta-5,7-dienol of 12.5 μM and a
V
max
of 0.59 nmol of this substrate metabolized/min/nmol of P-450. This enzyme is encoded by CYP61 (
ERG5
) in
Saccharomyces cerevisiae
, and homologues have been shown in the
Candida albicans
and
Schizosaccharomyces pombe
genome projects. Ketoconazole, itraconazole, and fluconazole formed low-spin complexes with the ferric cytochrome and exhibited type II spectra, which are indicative of an interaction between the azole moiety and the cytochrome heme. The azole antifungal compounds inhibited reconstituted sterol Δ
22
-desaturase activity by binding to the cytochrome with a one-to-one stoichiometry, with total inhibition of enzyme activity occurring when equimolar amounts of azole and cytochrome P-450 were added. These results reveal the potential for sterol Δ
22
-desaturase to be an antifungal target and to contribute to the binding of drugs within the fungal cell.
Effects of Novel 6-Desfluoroquinolones and Classic Quinolones on Pentylenetetrazole-Induced Seizures in Mice
Authors: De Sarro A. , Cecchetti V. , Fravolini V. , Naccari F. , Tabarrini O. , De Sarro G.
Published: October 2018

There have been several reports that convulsions, although rare, occur in patients who receive fluoroquinolones. In this study, the proconvulsant effects exhibited by a novel series of 6-desfluoroquinolones and some classic quinolones on pentylenetetrazole (PTZ)-induced seizures in mice were evaluated and compared. Animals were intraperitoneally injected with vehicle or quinolone derivatives (5 to 100 μg/g of body weight) 30 min before the subcutaneous (s.c.) administration of PTZ (40 μg/g). In each experiment, mice were then observed for 1 h to monitor for the incidence and onset of clonic seizures. The order of proconvulsant activity in our epileptic model was MF5184 > MF5187 > pefloxacin > MF5189 > ofloxacin > ciprofloxacin > MF5140 > MF5181 > MF5137 > rufloxacin > MF5143 > MF5158 > MF5191 > MF5128 > MF5138 > cinoxacin > MF5142 > norfloxacin > nalidixic acid. The relationship between the chemical structure and the proconvulsant activity of 6-desfluoroquinolone derivatives was studied. We observed that, in terms of toxicity to the central nervous system (CNS), besides the heterocyclic side chain (moiety) at the C-7 position, the C-6 substituent also appears to play an important role. In particular, a hydrogen at the C-6 position seemed to be responsible for major neurotoxic activity in comparison to an amino group located in the same position. The relationship between lipophilicity and proconvulsant activity was also investigated. We did not find any clear relationship between a higher level of lipophilicity and major proconvulsant properties. Although the principal mechanism by which quinolones induce potentiation of the proconvulsant effects of PTZ cannot be easily determined, it is possible that the convulsions are caused by drug interactions, because both PTZ and quinolones are believed to increase excitation of the CNS by inhibition of γ-aminobutyric acid binding to receptors.
Activation of the 2′- N -Acetyltransferase Gene [
aac
(
2′
)-
Ia
] in
Providencia stuartii
by an Interaction of AarP with the Promoter Region
Authors: Macinga David R. , Paradise Michael R. , Parojcic Milica M. , Rather Philip N.
Published: October 2018

The
aac
(
2′
)-
Ia
gene in
Providencia stuartii
encodes a 2′-
N
-acetyltransferase capable of acetylating both peptidoglycan and certain aminoglycoside antibiotics. Regulation of the
aac
(
2′
)-
Ia
gene is influenced in a positive manner by the product of the
aarP
gene, which encodes a small transcriptional activator of the AraC (XylS) family. In this study, we demonstrate the sequence requirements at the
aac
(
2′
)-
Ia
promoter for AarP binding and activation.
Anti-
Toxoplasma gondii
Activities and Structure-Activity Relationships of Novel Fluoroquinolones Related to Trovafloxacin
Authors: Khan Anis A. , Araujo Fausto G. , Brighty Katherine E. , Gootz Thomas D. , Remington Jack S.
Published: October 2018

Eleven novel fluoroquinolones closely related to trovafloxacin were evaluated for their in vitro activity against
Toxoplasma gondii
, and their structure-activity relationships were examined. The 50% inhibitory concentration (IC
50
) of trovafloxacin against
T. gondii
was 2.93 μM; the IC
50
of the 11 analogs ranged from 0.53 to 14.09 μM. Six analogs had IC
50
s lower than that of trovafloxacin. Examination of the structure-activity relationships of the compounds revealed that addition of a -CH
3
at C-5 of the 1,8-naphthyridone ring, at C-2 of the azabicyclohexane ring, or on the -NH
2
at the 6 position of the azabicyclohexane ring resulted in a four- to sixfold increase in activity. Moreover, replacement of 2,4-difluorophenyl by cyclopropyl at N-1 of the 1,8-naphthyridone ring increased activity twofold, and moving the -NH
2
one atom further away from the azabicyclohexane ring decreased activity. There was no difference between the naphthyridone and quinolone analogs. These results indicate that structure-activity studies of compounds related to drugs active against
T. gondii
may be useful in producing compounds with more potent activities against the parasite.
In Vitro and In Vivo Activities of Tea Catechins against
Helicobacter pylori
Authors: Mabe Katsuhiro , Yamada Masami , Oguni Itaro , Takahashi Tsuneo
Published: October 2018

The catechin epigallocatechin gallate showed the strongest activity of the six tea catechins tested against
Helicobacter pylori
(MIC for 50% of the strains tested, 8 μg/ml). It had bactericidal activity at pH 7 but not at pH ≤5.0. In infected Mongolian gerbils,
H. pylori
was eradicated in 10 to 36% of the catechin-treated animals, with significant decreases in mucosal hemorrhage and erosion. Tea catechins, therefore, may have therapeutic effects on
H. pylori
infection.
Altered Pharmacokinetics of Ceftazidime in Critically Ill Patients
Authors: Gómez C. M. H. , Cordingly J. J. , Palazzo M. G. A.
Published: October 2018

Many critically ill patients have increased extracellular fluid which might affect ceftazidime pharmacokinetics. We investigated the pharmacokinetics of ceftazidime in 15 adult intensive care patients receiving 2 g of ceftazidime intravenously three times a day. The ceftazidime mean (standard deviation) apparent volume of distribution and terminal-phase half-life were 56.91 (25.93) liters and 4.75 (1.85) h, respectively, significantly greater than values reported previously for healthy controls (
P
< 0.001). The mean ceftazidime clearance and area under the curve at steady state were not significantly different from those previously reported for controls. We conclude that ceftazidime pharmacokinetics in critically ill patients were altered by an increased volume of drug distribution and elevated elimination half-life.
Anti-Human Immunodeficiency Virus Type 1 Activity, Intracellular Metabolism, and Pharmacokinetic Evaluation of 2′-Deoxy-3′-Oxa-4′-Thiocytidine
Authors: de Muys Jean-Marc , Gourdeau Henriette , Nguyen-Ba Nghe , Taylor Debra L. , Ahmed Parvin S. , Mansour Tarek , Locas Celine , Richard Nathalie , Wainberg Mark A. , Rando Robert F.
Published: October 2018

The racemic nucleoside analogue 2′-deoxy-3′-oxa-4′-thiocytidine (dOTC) is in clinical development for the treatment of human immunodeficiency virus (HIV) type 1 (HIV-1) infection. dOTC is structurally related to lamivudine (3TC), but the oxygen and sulfur in the furanosyl ring are transposed. Intracellular metabolism studies showed that dOTC is phosphorylated within cells via the deoxycytidine kinase pathway and that approximately 2 to 5% of dOTC is converted into the racemic triphosphate derivatives, which had measurable half-lives (2 to 3 hours) within cells. Both 5′-triphosphate (TP) derivatives of dOTC were more potent than 3TC-TP at inhibiting HIV-1 reverse transcriptase (RT) in vitro. The

K
i

values for dOTC-TP obtained against human DNA polymerases α, β, and γ were 5,000-, 78-, and 571-fold greater, respectively, than those for HIV RT (28 nM), indicating a good selectivity for the viral enzyme. In culture experiments, dOTC is a potent inhibitor of primary isolates of HIV-1, which were obtained from antiretroviral drug-naive patients as well as from nucleoside therapy-experienced (3TC- and/or zidovudine [AZT]-treated) patients. The mean 50% inhibitory concentration of dOTC for drug-naive isolates was 1.76 μM, rising to only 2.53 and 2.5 μM for viruses resistant to 3TC and viruses resistant to 3TC and AZT, respectively. This minimal change in activity is in contrast to the more dramatic changes observed when 3TC or AZT was evaluated against these same viral isolates. In tissue culture studies, the 50% toxicity levels for dOTC, which were determined by using [
3
H]thymidine uptake as a measure of logarithmic-phase cell proliferation, was greater than 100 μM for all cell lines tested. In addition, after 14 days of continuous culture, at concentrations up to 10 μM, no measurable toxic effect on HepG2 cells or mitochondrial DNA replication within these cells was observed. When administered orally to rats, dOTC was well absorbed, with a bioavailability of approximately 77%, with a high proportion (approximately 16.5% of the levels in serum) found in the cerebrospinal fluid.
Effect of Carbon Dioxide on Testing of Susceptibilities of Respiratory Tract Pathogens to Macrolide and Azalide Antimicrobial Agents
Authors: Johnson M. M. , Hill S. L. , Piddock Laura J. V.
Published: October 2018

The in vitro activities of erythromycin, azithromycin, and clarithromycin against 178 clinical isolates from the lower respiratory tract of patients with chronic obstructive pulmonary disease were determined by an agar dilution method. The plates were incubated in air alone or in 5% carbon dioxide. The MICs measured in air alone were lower for most isolates than those measured in 5% carbon dioxide, illustrating the “pH effect” of incubation in carbon dioxide. Testing of isolates in 5% carbon dioxide on pH-adjusted medium (pH 8.4) resulted in MICs of one or two doubling dilutions lower than those obtained on agar with a neutral pH. A bioassay of the three agents incubated in air and in 5% carbon dioxide resulted in a significant loss of activity of all three agents in the carbon dioxide-enriched atmosphere. However, this loss-of-activity effect was significantly reduced when the bioassay medium was adjusted to pH 8.4 prior to incubation in 5% carbon dioxide.
Inhibition of Polyamine Synthesis Arrests Trichomonad Growth and Induces Destruction of Hydrogenosomes
Authors: Reis Isabela A. , Martinez Martha P. , Yarlett Nigel , Johnson Patricia J. , Silva-Filho Fernando C. , Vannier-Santos Marcos A.
Published: October 2018

Trichomonad parasites such as
Tritrichomonas foetus
produce large amounts of putrescine (1,4-diaminobutane), which is transported out of the cell via an antiport mechanism which results in the uptake of a molecule of spermine. The importance of putrescine to the survival of the parasite and its role in the biology of
T. foetus
was investigated by use of the putrescine analogue 1,4-diamino-2-butanone (DAB). Growth of
T. foetus
in vitro was significantly inhibited by 20 mM DAB, which was reversed by the addition of exogenous 40 mM putrescine. High-performance liquid chromatography analysis of 20 mM DAB-treated
T. foetus
revealed that putrescine, spermidine, and spermine levels were reduced by 89, 52, and 43%, respectively, compared to those in control cells. The DAB treatment induced several ultrastructural alterations, which were primarily observed in the redox organelles termed hydrogenosomes. These organelles were progressively degraded, giving rise to large vesicles that displayed material immunoreactive with an antibody to β-succinyl-coenzyme A synthetase, a hydrogenosomal enzyme. A protective role for polyamines as stabilizing agents in the trichomonad hydrogenosomal membrane is proposed.
Emergence of Drug-Resistant Populations of Woodchuck Hepatitis Virus in Woodchucks Treated with the Antiviral Nucleoside Lamivudine
Authors: Zhou Tianlun , Saputelli Jeffry , Aldrich Carol E. , Deslauriers Manon , Condreay Lynn D. , Mason William S.
Published: October 2018

Lamivudine [(−)-β-
l
-2′,3′-dideoxy-3′-thiacytidine] reduces woodchuck hepatitis virus (WHV) titers in the sera of chronically infected woodchucks by inhibiting viral DNA synthesis. However, after 6 to 12 months, WHV titers begin to increase toward pretreatment levels. Three WHV variants with mutations in the active site of the DNA polymerase gene are present at this time (W. S. Mason et al., Virology 245:18–32, 1998). We have asked if these mutant viruses were responsible for the lamivudine resistance and if their emergence caused an immediate rise in virus titers. Cell cultures studies implied that the mutants were resistant to lamivudine. Emergence of mutant WHV was not always associated, however, with an immediate rise in virus titers in the serum. One of the three types of mutant viruses became prominent in serum up to 7 months before titers in serum actually began to increase, at a time when wild-type virus was still predominant in the liver. The two other mutants did not show this behavior but were detected in serum and liver later, just at the time that virus titers began to rise. A factor linking all three mutants was that a similar duration of drug administration preceded the rise in titers, irrespective of which mutant ultimately prevailed. A simple explanation for these results is that the increase in virus titers following emergence of drug-resistant mutants can occur only as the preexisting wild-type virus is cleared from the hepatocyte population, allowing spread of the mutants. Thus, prolonged suppression of virus titers in the serum may sometimes be a measure of the stability of hepatocyte infection rather than of a successful therapeutic outcome.
In Vitro Antibacterial Activity of LJC 11,036, an Active Metabolite of L-084, a New Oral Carbapenem Antibiotic with Potent Antipneumococcal Activity
Authors: Hikida Muneo , Itahashi Kouju , Igarashi Atsumi , Shiba Toshiharu , Kitamura Masataka
Published: October 2018

LJC 11,036 is the active metabolite of L-084, a novel oral carbapenem that exhibits potent broad-spectrum activity. Antibacterial activities of LJC 11,036 against clinical isolates from respiratory infections, such as
Streptococcus pneumoniae
(
n
= 52),
Streptococcus pyogenes
(
n
= 19),
Haemophilus influenzae
(
n
= 50),
Klebsiella pneumoniae
(
n
= 53), and
Moraxella catarrhalis
(
n
= 53), and from urinary-tract infections, such as
Escherichia coli
(
n
= 53) (MICs at which 90% of the isolates were inhibited [MIC
90
s], 0.1, ≤0.006, 0.39, 0.05, 0.05, and 0.05 μg/ml, respectively), were 2- to 64-fold higher than those of imipenem, cefdinir, and faropenem. Moreover, against these bacterial species, except for
H. influenzae
, the MIC
90
s of LJC 11,036 were 4- to 512-fold lower than those of levofloxacin. LJC 11,036 showed bactericidal activity equal or superior to that of imipenem. Bactericidal activity against penicillin-resistant
S. pneumoniae
(PRSP) did not vary with the phase of growth. LJC 11,036 had potent activity against various β-lactamase-producing strains, excluding carbapenemase producers. Against renal dehydropeptidase-I, LJC 11,036 was more stable than imipenem. Furthermore, LJC 11,036 produced in vitro postantibiotic sub-MIC effects against PRSP HSC-3 (6.0 h at one-fourth the MIC) and
H. influenzae
LJ5 (9.2 h at one-half the MIC). LJC 11,036 showed high binding affinities for PBP1A, -1B, -2A/2X, -2B, and -3 of PRSP and for PBP1B, -2, -3A, and -3B of
H. influenzae
.
Comparative In Vitro Activities of Ciprofloxacin, Clinafloxacin, Gatifloxacin, Levofloxacin, Moxifloxacin, and Trovafloxacin against
Klebsiella pneumoniae
,
Klebsiella oxytoca
,
Enterobacter cloacae
, and
Enterobacter aerogenes
Clinical Isolates with Alterations in GyrA and ParC Proteins
Authors: Brisse Sylvain , Milatovic Dana , Fluit Ad C. , Verhoef Jan , Martin Nele , Scheuring Sybille , Köhrer Karl , Schmitz Franz-Josef
Published: October 2018

The in vitro activities of ciprofloxacin, clinafloxacin, gatifloxacin, levofloxacin, moxifloxacin, and trovafloxacin were tested against 72 ciprofloxacin-resistant and 28 ciprofloxacin-susceptible isolates of
Klebsiella pneumoniae
,
Klebsiella oxytoca
,
Enterobacter cloacae
, and
Enterobacter aerogenes
. Irrespective of the alterations in GyrA and ParC proteins, clinafloxacin exhibited greater activity than all other fluoroquinolones tested against
K. pneumoniae
and
E. aerogenes
.
Analysis of Rifapentine for Preventive Therapy in the Cornell Mouse Model of Latent Tuberculosis
Authors: Miyazaki Eishi , Chaisson Richard E. , Bishai William R.
Published: October 2018

Rifapentine is a long-acting rifamycin which may be useful for intermittent drug therapy against tuberculosis. In this study we measured the efficacies of rifapentine-containing intermittent drug regimens for preventive therapy using the Cornell mouse model of latent tuberculosis. We infected groups of mice intravenously with
Mycobacterium tuberculosis
and then treated them with isoniazid and pyrazinamide for 12 weeks according to the Cornell latency development protocol. After a 4-week interval of no treatment, experimental preventive therapy was administered by esophageal gavage for 12 or 18 weeks. After equilibration and dexamethasone amplification treatment, mouse organs were analyzed by quantitative colony counts to measure the effectiveness of therapy. Our results showed that once-weekly isoniazid plus rifapentine combination therapy for 18 weeks was an effective preventive regimen with sterilizing potency and bacillary load reduction comparable to those of daily isoniazid therapy for 18 weeks. Monotherapy with rifapentine weekly or fortnightly or with rifampin twice weekly for up to 18 weeks did not offer advantages in reducing bacillary load or in sterilizing organs compared to the effects of a placebo. These results with the Cornell mouse model indicate that once-weekly, short-course preventive therapy with isoniazid plus rifapentine is effective and may warrant investigation in humans with latent tuberculosis infection.
Comparative Studies of Mutations in Animal Isolates and Experimental In Vitro- and In Vivo-Selected Mutants of
Salmonella
spp. Suggest a Counterselection of Highly Fluoroquinolone-Resistant Strains in the Field
Authors: Giraud Etienne , Brisabois Anne , Martel Jean-Louis , Chaslus-Dancla Elisabeth
Published: October 2018

The occurrence of mutations in the genes coding for gyrase (
gyrA
and
gyrB
) and topoisomerase IV (
parE
and
parC
) of
Salmonella typhimurium
experimental mutants selected in vitro and in vivo and of 138 nalidixic acid-resistant
Salmonella
field isolates was investigated. The sequencing of the quinolone resistance-determining region of these genes in highly fluoroquinolone-resistant mutants (MICs of 4 to 16 μg/ml) revealed the presence of
gyrA
mutations at codons corresponding to Gly-81 or Ser-83, some of which were associated with a mutation at Asp-87. No mutations were found in the
gyrB
,
parC
, and
parE
genes. An assay combining allele-specific PCR and restriction fragment length polymorphism was developed to rapidly screen mutations at codons 81, 83, and 87 of
gyrA
. The MICs of ciprofloxacin for the field isolates reached only 2 μg/ml, versus 16 μg/ml for some in vitro-selected mutants. The field isolates, like the mutants selected in vivo, had only a single
gyrA
mutation at codon 83 or 87. Single
gyrA
mutations were also found in highly resistant in vitro-selected mutants (MIC of ciprofloxacin, 8 μg/ml), which indicates that mechanisms other than the unique modification of the intracellular targets could participate in fluoroquinolone resistance in
Salmonella
spp. A comparison of experimental mutants selected in vitro, field strains, and mutants selected in vivo suggests that highly fluoroquinolone-resistant strains are counterselected in field conditions in the absence of selective pressure.
Antifungal Activity of LY303366, a Novel Echinocandin B, in Experimental Disseminated Candidiasis in Rabbits
Authors: Petraitiene Ruta , Petraitis Vidmantas , Groll Andreas H. , Candelario Myrna , Sein Tin , Bell Aaron , Lyman Caron A. , McMillian Carl L. , Bacher John , Walsh Thomas J.
Published: October 2018

The safety and antifungal activity of LY303366 (LY), a new broad-spectrum semisynthetic echinocandin, were studied against disseminated candidiasis in persistently neutropenic rabbits. In vitro time-kill assays demonstrated that LY has concentration-dependent fungicidal activity. The pharmacokinetics of LY in the plasma of nonneutropenic rabbits suggested a linear relationship between dose and area under the curve (AUC). The times spent above the MIC during the experimental dosing interval of 24 h were 4 h for LY at 0.1 mg/kg of body weight/day (LY0.1), 8 h for LY at 0.25 mg/kg/day (LY0.25), 12 h for LY at 0.5 mg/kg/day (LY0.5), and 20 h for LY at 1 mg/kg/day (LY1). Antifungal therapy was administered to infected rabbits for 10 days starting 24 h after the intravenous (i.v.) inoculation of 10
3
Candida albicans
blastoconidia. Study groups consisted of untreated controls (UCs) and animals treated with amphotericin B (AmB; 1 mg/kg/day i.v.), fluconazole (FLU; 10 mg/kg/day i.v.), and LY0.1, LY0.25, LY0.5, or LY1 i.v. Rabbits treated with LY0.5, LY1, AmB, and FLU had similarly significant clearance of
C. albicans
from the liver, spleen, kidney, lung, vena cava, and brain in comparison to that for UCs. There was a dose-dependent clearance of
C. albicans
from tissues in response to LY. Among rabbits treated with LY0.1 there was a significant reduction of
C. albicans
only in the spleen. In animals treated with LY0.25 there was a significant reduction in all tissues but the brain. By comparison, LY0.5 and LY1 cleared all tissues, including the brain, of
C. albicans
. These in vivo findings were consistent with the results of in vitro time-kill assays. A dose-dependent effect of altered cell wall morphology was observed among UCs and animals treated with LY0.1, and LY0.25, with a progressive transition from hyphal structure to disrupted yeast forms. Serum creatinine levels were higher and serum potassium levels were lower in AmB-treated rabbits than in UCs and LY- and FLU-treated rabbits. LY0.5 and LY1 were well tolerated, displayed predictable pharmacokinetics in plasma, and had activities comparable to those of AmB and FLU in the treatment of disseminated candidiasis in persistently neutropenic rabbits.
VanE, a New Type of Acquired Glycopeptide Resistance in
Enterococcus faecalis
BM4405
Authors: Fines Marguerite , Perichon Bruno , Reynolds Peter , Sahm Daniel F. , Courvalin Patrice
Published: October 2018

Enterococcus faecalis
BM4405 was resistant to low levels of vancomycin (MIC, 16 μg/ml) and was susceptible to teicoplanin (MIC, 0.5 μg/ml). No PCR product was obtained when the total DNA of this clinical isolate was used as a template with primers specific for glycopeptide resistance genes
vanA
,
vanB
,
vanC
, and
vanD
. However, a 604-bp PCR fragment was obtained when V1 and V2 degenerate primers were used and total DNA was digested with
Hin
dIII as a template. The product was cloned and sequenced. The deduced amino acid sequence had greater identity (55%) with VanC than with VanA (45%), VanB (43%), or VanD (44%). This was consistent with the fact that BM4405 synthesized peptidoglycan precursors that terminated in
d
-serine residues. After induction with vancomycin, weak
d
,
d
-dipeptidase and penicillin-insensitive
d
,
d
-carboxypeptidase activities were detected in cytoplasmic extracts of BM4405, whereas a serine racemase activity was found in the membrane preparation. This new type of acquired glycopeptide resistance was named VanE.
A New Azole Derivative of 1,4-Benzothiazine Increases the Antifungal Mechanisms of Natural Effector Cells
Authors: Pitzurra Lucia , Fringuelli Renata , Perito Stefano , Schiaffella Fausto , Barluzzi Roberta , Bistoni Francesco , Vecchiarelli Anna
Published: October 2018

The most widely used drug for treatment of candidiasis is fluconazole (FCZ). Recently, a new derivative of 1,4-benzothiazine, compound FS5, was developed. FS5 had an appreciable protective effect against murine candidiasis. The present study was designed to dissect the antifungal mechanisms triggered by FS5 and to establish whether this compound could enhance the antimicrobial abilities of natural effector cells. The results show that intraperitoneal injection of FS5 in mice (i) induced an increase in circulating neutrophil levels comparable to that observed in FCZ-treated mice; (ii) enhanced phagocytosis and the killing activities of macrophages (Mφs) isolated from the spleen or peritoneal cavity, with the latter effect correlating with induction of nitric oxide synthesis and production by Mφs; and (iii) increased the levels of expression and synthesis of tumor necrosis factor alpha. These results suggest that the compound-induced synthesis of antimicrobial and proinflammatory molecules by heterogeneous Mφ populations is part of the beneficial effect of FS5 exerted against murine candidiasis.
Low-Dose Treatment with Sulfadoxine-Pyrimethamine Combinations Selects for Drug-Resistant
Plasmodium falciparum
Strains
Authors: Kun Jürgen F. J. , Lehman Leopold G. , Lell Bertrand , Schmidt-Ott Ruprecht , Kremsner Peter G.
Published: October 2018

A total of 252 children were enrolled in a drug trial to assess the effect of minimal doses of sulfadoxine (Sdx) and pyrimethamine (Pyr). Parasite samples isolated from these patients were analyzed before and after treatment to investigate the level of drug-resistant strains. The parasite genes encoding dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) were assayed for point mutations that are associated with resistance against drugs. Before treatment, Pyr
r
genotypes of the DHFR gene were found in 42% of all samples, 8% of the patients harbored a mixed parasite population and 50% had a sensitive DHFR genotype. In terms of the DHPS gene, we found mutations in 45% of the parasites. Twenty-four percent had a Ser
436
mutation, and 26% had a Gly
437
mutation. Recrudescent parasites were highly enriched for both Pyr
r
and Sdx
r
strains after treatment (
P
< 0.001 and
P
= 0.029, respectively).
Enterococci with Glycopeptide Resistance in Turkeys, Turkey Farmers, Turkey Slaughterers, and (Sub)Urban Residents in the South of The Netherlands: Evidence for Transmission of Vancomycin Resistance from Animals to Humans?
Authors: Stobberingh Ellen , van den Bogaard Anthony , London Nancy , Driessen Christel , Top Janetta , Willems Rob
Published: October 2018

The number of vancomycin-resistant enterococci (VRE) relative to the total number of enterococci was determined in fecal samples from turkeys and three human populations in 1996, each with a different level of contact with turkeys, i.e., turkey farmers, turkey slaughterers, and (sub)urban residents. The percentage of VRE relative to the total enterococcal population (i.e., the degree of resistance) was low (2 to 4%) in all groups (except in six samples). No difference was observed between farmers who used avoparcin and those who did not. The pulsed-field gel electrophoresis (PFGE) patterns of the VRE isolates from the different populations were quite heterogeneous, but isolates with the same PFGE pattern were found among animal and human isolates, in addition to the isolates which were described previously (A. E. van den Bogaard, L. B. Jensen, and E. E. Stobberingh, N. Engl. J. Med. 337:1558–1559, 1997). Detailed molecular characterization of
vanA
-containing transposons from different isolates showed, that in addition to a previously reported strain, similar transposons were present in VRE isolates from turkeys and turkey farmers. Moreover, similar VanA elements were found not only in isolates with the same PFGE pattern but also in other strains from both humans and animals.
In Vitro Activity of Gemifloxacin (SB 265805) against Anaerobes
Authors: Goldstein Ellie J. C. , Citron Diane M. , Warren Yumi , Tyrrell Kerin , Merriam C. Vreni
Published: October 2018

Gemifloxacin mesylate (SB 265805), a new fluoronaphthyridone, was tested against 359 recent clinical anaerobic isolates by the National Committee for Clinical Laboratory Standards reference agar dilution method with supplemented brucella blood agar and an inoculum of 10
5
CFU/spot. Comparative antimicrobials tested included trovafloxacin, levofloxacin, grepafloxacin, sparfloxacin, sitafloxacin (DU-6859a), penicillin G, amoxicillin clavulanate, imipenem, cefoxitin, clindamycin, and metronidazole. The MIC
50
and MIC
90
(MICs at which 50 and 90% of the isolates were inhibited) of gemifloxacin against various organisms (with the number of strains tested in parentheses) were as follows (in micrograms per milliliter): for
Bacteroides fragilis
(28), 0.5 and 2; for
Bacteroides thetaiotaomicron
(24), 1 and 16; for
Bacteroides caccae
(12), 1 and 16; for
Bacteroides distasonis
(12), 8 and >16; for
Bacteroides ovatus
(12), 4 and >16; for
Bacteroides stercoris
(12), 0.5 and 0.5; for
Bacteroides uniformis
(12), 1 and 4; for
Bacteroides vulgatus
(11), 4 and 4; for
Clostridium clostridioforme
(15), 0.5 and 0.5; for
Clostridium difficile
(15), 1 and >16; for
Clostridium innocuum
(13), 0.125 and 2; for
Clostridium perfringens
(13), 0.06 and 0.06; for
Clostridium ramosum
(14), 0.25 and 8; for
Fusobacterium nucleatum
(12), 0.125 and 0.25; for
Fusobacterium necrophorum
(11), 0.25 and 0.5; for
Fusobacterium varium
(13), 0.5 and 1; for
Fusobacterium
spp. (12), 1 and 2; for
Peptostreptococcus anaerobius
(13), 0.06 and 0.06; for
Peptostreptococcus asaccharolyticus
(13), 0.125 and 0.125; for
Peptostreptococcus magnus
(14), 0.03 and 0.03; for
Peptostreptococcus micros
(12), 0.06 and 0.06; for
Peptostreptococcus prevotii
(14), 0.06 and 0.25; for
Porphyromonas asaccharolytica
(11), 0.125 and 0.125; for
Prevotella bivia
(10), 8 and 16; for
Prevotella buccae
(10), 2 and 2; for
Prevotella intermedia
(10), 0.5 and 0.5; and for
Prevotella melaninogenica
(11), 1 and 1. Gemifloxacin mesylate (SB 265805) was 1 to 4 dilutions more active than trovafloxacin against fusobacteria and peptostreptococci, and the two drugs were equivalent against clostridia and
P. asaccharolytica
. Gemifloxacin was equivalent to sitafloxacin (DU 6859a) against peptostreptococci,
C. perfringens
, and
C. ramosum
, and sitafloxacin was 2 to 3 dilutions more active against fusobacteria. Sparfloxacin, grepafloxacin, and levofloxacin were generally less active than gemifloxacin against all anaerobes.
In Vitro Activities of BMS-207147 against Over 600 Contemporary Clinical Bloodstream Isolates of
Candida
Species from the SENTRY Antimicrobial Surveillance Program in North America and Latin America
Authors: Diekema D. J. , Pfaller M. A. , Messer S. A. , Houston A. , Hollis R. J. , Doern G. V. , Jones R. N. ,   The SENTRY PARTICIPANTS GROUP
Published: October 2018

We compared the in vitro activity of BMS-207147, an investigational triazole, with those of itraconazole and fluconazole against 613 clinical bloodstream isolates of
Candida
spp. collected from SENTRY participating hospitals during 1997 and 1998. Overall, BMS-207147 was the most active azole against all
Candida
spp. While both BMS-207147 and itraconazole displayed a stepwise decrease in activity against isolates for which the fluconazole MICs were elevated, BMS-207147 had two- to fourfold greater activity than itraconazole both against
Candida
spp. that were dose-dependently fluconazole susceptible and against those that were fluconazole resistant.
Quantitation of Intracellular Triphosphate of Emtricitabine in Peripheral Blood Mononuclear Cells from Human Immunodeficiency Virus-Infected Patients
Authors: Darque Albert , Valette Gilles , Rousseau Frank , Wang Laurene H. , Sommadossi Jean-Pierre , Zhou Xiao-Jian
Published: October 2018

An analytical methodology combining solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) was developed to quantitate the intracellular active 5′-triphosphate (TP) of β-
l
-2′,3′-dideoxy-5-fluoro-3′-thiacytidine (emtricitabine) (FTC) in human peripheral blood mononuclear cells (PBMCs). The FTC nucleotides, including 5′-mono-, di-, and triphosphates, were successively resolved on an anion-exchange SPE cartridge by applying a gradient of potassium chloride. The FTC-TP was subsequently digested to release the parent nucleoside that was finally analyzed by HPLC with UV detection (HPLC-UV). Validation of the methodology was performed by using PBMCs from healthy donors exposed to an isotopic solution of [
3
H]FTC with known specific activity, leading to the formation of intracellular FTC-TP that was quantitated by an anion-exchange HPLC method with radioactive detection. These levels of FTC-TP served as reference values and were used to validate the data obtained by HPLC-UV. The assay had a limit of quantitation of 4.0 pmol of FTC-TP (amount on column from approximately 10
7
cells). Intra-assay precision (coefficient of variation percentage of repeated measurement) and accuracy (percentage deviation of the nominal reference value), estimated by using quality control samples at 16.2, 60.7, and 121.5 pmol, ranged from 1.3 to 3.3% and −1.0 to 4.8%, respectively. Interassay precision and accuracy varied from 3.0 to 10.2% and from 2.5 to 6.7%, respectively. This methodology was successfully applied to the determination of FTC-TP in PBMCs of patients infected with human immunodeficiency virus after oral administration of various dosing regimens of FTC monotherapy.
In Vitro Activities of Azithromycin and Ofloxacin againstChlamydia pneumoniaein a Continuous-Infection Model
Authors: Kutlin Andrei , Roblin Patricia M. , Hammerschlag Margaret R.
Published: October 2018

Chlamydia pneumoniaeis a well-established cause of community-acquired pneumonia and bronchitis in adults and children. Chronic infections withC. pneumoniaehave been implicated in the development of atherosclerosis and other diseases in humans. Methods currently used for the culture and propagation ofC. pneumoniaeare not analogous to the infection as it occurs in vivo. We have established a model of continuousC. pneumoniaeinfection in vitro. HEp-2 cells inoculated with CM-1 and TW-183 strains have been persistently infected for periods of over 1.5 and 2 years, respectively. The cultures were maintained without centrifugation or the addition of cycloheximide, fresh host cells, or chlamydia. We observed cycles of host cell lysis, detachment, and regrowth with both strains ofC. pneumoniae. ContinuousC. pneumoniaeinfections may more closely resemble the actual events as they occur in vivo and, therefore, may be a better model for the in vitro study ofC. pneumoniaeinfection. When we used continuously infected cells to determine the effects of azithromycin and ofloxacin onC. pneumoniaepropagation in vitro, we found that both drugs reduced but did not completely eliminate the organism. This may be an important observation, as the failure of antibiotic therapy againstC. pneumoniaeinfection in humans has been described.
Incidence of Quinolone Resistance Over the Period 1986 to 1998 in Veterinary
Salmonella
Isolates from Germany
Authors: Malorny Burkhard , Schroeter Andreas , Helmuth Reiner
Published: October 2018

A total of 24,591 nonhuman salmonella strains isolated in Germany between 1986 and 1998 were examined for their resistance to nalidixic acid by an agar diffusion method. The rate of resistance (inhibition zone, ≤13 mm) ranged from 0.2% in 1986 to a peak of 14.8% in 1990. Between 1991 and 1998 the MICs for nalidixic acid-resistant strains ranged from more than 256 μg/ml for nalidixic acid to between 0.25 and 128 μg/ml for enrofloxacin. In the early 1990s a particularly high incidence of fluoroquinolone resistance (49.5%) was seen among isolates of
Salmonella enterica
serotype Typhimurium (
Salmonella
Typhimurium) definitive phage type 204c that mainly originated from cattle. Among isolates from poultry an increase in the incidence of nalidixic acid resistance to a peak of 14.4% was observed in 1994. This peak was due to the presence of specific resistant serotypes, mainly serotypes Hadar, Saintpaul, Paratyphi B (
d
-tartrate positive; formerly serotype Java) and Newport. Such strains exhibited a decreased susceptibility to enrofloxacin (MIC, 1 μg/ml). Among isolates from pigs the peak incidence of resistance was reached in 1993, with 7.5% of isolates resistant to nalidixic acid and enrofloxacin. The study demonstrates an increase in the incidence of strains that are resistant to nalidixic acid and that have decreased susceptibility to enrofloxacin after the licensing of enrofloxacin. In addition, the number of other serotypes that exhibited nalidixic acid resistance or reduced enrofloxacin susceptibility increased among the total number of isolates investigated between 1992 and 1998.
Influence of Cefodizime on Pulmonary Inflammatory Response to Heat-Killed
Klebsiella pneumoniae
in Mice
Authors: Bergeron Yves , Deslauriers Anne-Marie , Ouellet Nathalie , Gauthier Marie-Christine , Bergeron Michel G.
Published: October 2018

Encapsulated
Klebsiella pneumoniae
strains frequently induce fatal nosocomial pneumonia. Cefodizime (CEF) as an antibiotic is suspected to enhance host resistance against various microbial invasions through interactions with bacteria and host cells. To investigate the influence of CEF on the pulmonary response to
Klebsiella
that does not merely result from direct bacterial clearance by the drug, we inoculated mice with heat-killed fluorescein isothiocyanate-labeled
K. pneumoniae
. CEF upregulated (
P
< 0.01) the early
Klebsiella
-induced secretion of tumor necrosis factor alpha, as well as the number (
P
< 0.01) and phagocytic efficacy (
P
< 0.001) of alveolar macrophages. By contrast, the late polymorphonuclear neutrophil recruitment (
P
< 0.05) and levels of interleukin-1 alpha (IL-1α) (
P
< 0.05) and IL-6 (
P
< 0.05) were reduced. The stimulation of an early immune response by CEF followed by late reduction in inflammation may be beneficial against bacterial pneumonia.
In Vitro Activities of Fluoroquinolones against Antibiotic-Resistant Blood Culture Isolates of Viridans Group Streptococci from across Canada
Authors: de Azavedo J. C. S. , Trpeski L. , Pong-Porter S. , Matsumura S. ,   The Canadian Bacterial Surveillance Network, Low D. E.
Published: October 2018

Among 418 blood culture isolates of viridans group streptococci obtained between 1995 and 1997, the in vitro rates of nonsusceptibility to penicillin, erythromycin, tetracycline, and trimethoprim-sulfamethoxazole were 28, 29, 24, and 14%, respectively. The most prevalent group (125 strains) was
Streptococcus mitis
, followed by
Streptococcus sanguis
(56 strains). For 236 (56%) strains resistant to one or more antibiotics, the ciprofloxacin MIC at which 90% of the isolates were inhibited (MIC
90
) was 4 μg/ml, whereas the MIC
90
s of trovafloxacin, grepafloxacin, and gatifloxacin were 0.25 μg/ml.
Lack of In Vitro Antimicrosporidian Activity of Thalidomide
Authors: Ridoux Olivier , Drancourt Michel
Published: October 2018

Thalidomide was evaluated for its in vitro activity againstEncephalitozoonspecies by using the MRC-5 cell system. A cytotoxic effect was observed for concentrations of 101μg/ml (P< 105) and 5 μg/ml (P< 105). Thalidomide did not significantly inhibit the growth of any of the microsporidia under study. These data suggest that thalidomide is not an etiologic treatment in microsporidial enteritis.
Cefoperazone Prevents the Inactivation of α1-Antitrypsin by Activated Neutrophils
Authors: Dallegri Franco , Dapino Patrizia , Arduino Nicoletta , Bertolotto Maria , Ottonello Luciano
Published: October 2018

At sites of neutrophilic inflammation, tissue injury by neutrophil elastase is favored by phagocyte-induced hypochlorous acid-dependent inactivation of the natural elastase inhibitor α1-antitrypsin. In the present study, cefoperazone prevented α1-antitrypsin inactivation by neutrophils and reduced the recovery of hypochlorous acid from these cells. Moreover, the antibiotic reduced the free elastase activity in a neutrophil suspension supplemented with α1-antitrypsin without affecting the cells’ ability to release elastase. These data suggest that the drug inactivates hypochlorous acid before its reaction with α1-antitrypsin, thereby permitting the antiprotease-mediated blockade of released elastase. In conclusion, cefoperazone appears to have the potential for limiting elastase-antielastase imbalances, attenuating the related tissue injury at sites of inflammation.
Antimicrobial Susceptibility Testing of
Chlamydia trachomatis
Using a Reverse Transcriptase PCR-Based Method
Authors: Cross N. A. , Kellock D. J. , Kinghorn G. R. , Taraktchoglou M. , Bataki E. , Oxley K. M. , Hawkey P. M. , Eley A.
Published: October 2018

The conventional method for antimicrobial susceptibility testing of
Chlamydia trachomatis
is subjective and potentially misleading. We have developed a reverse transcriptase PCR (RT-PCR)-based method which is more sensitive and less subjective than the conventional method. Using 16 strains of
C. trachomatis
in triplicate assays, we found the RT-PCR method consistently more sensitive than the conventional technique for all eight antimicrobials tested, with resultant MICs determined by RT-PCR ranging from 1.6-fold higher (erythromycin) to ≥195-fold higher (amoxicillin).
Activities of New Antimicrobial Agents (Trovafloxacin, Moxifloxacin, Sanfetrinem, and Quinupristin-Dalfopristin) against
Bacteroides fragilis
Group: Comparison with the Activities of 14 Other Agents
Authors: Betriu Carmen , Gómez María , Palau M. Luisa , Sánchez Ana , Picazo Juan J.
Published: October 2018

The antimicrobial activities of trovafloxacin, moxifloxacin, sanfetrinem, quinupristin-dalfopristin, and 14 other antimicrobial agents against 218
Bacteroides fragilis
group strains were determined. A group of 10 imipenem-resistant strains were also tested. Imipenem, meropenem, and sanfetrinem had the lowest MICs of all of the β-lactams. Quinupristin-dalfopristin inhibited all of the strains at 2 μg/ml. Overall, the MICs of trovafloxacin and moxifloxacin for 90% of the strains tested were 1 and 2 μg/ml, respectively.
Atg5
Supports
Rickettsia australis
Infection in Macrophages
In Vitro
and
In Vivo
Authors: Bechelli Jeremy , Vergara Leoncio , Smalley Claire , Buzhdygan Tetyana P. , Bender Sean , Zhang William , Liu Yan , Popov Vsevolod L. , Wang Jin , Garg Nisha , Hwang Seungmin , Walker David H. , Fang Rong
Published: October 2018

Rickettsiae can cause life-threatening infections in humans. Macrophages are one of the initial targets for rickettsiae after inoculation by ticks.
Therapeutic use of intermittent fasting for people with type 2 diabetes as an alternative to insulin
Authors: Furmli Suleiman , Elmasry Rami , Ramos Megan , Fung Jason
Published: October 2018

This case series documents three patients referred to the Intensive Dietary Management clinic in Toronto, Canada, for insulin-dependent type 2 diabetes. It demonstrates the effectiveness of therapeutic fasting to reverse their insulin resistance, resulting in cessation of insulin therapy while maintaining control of their blood sugars. In addition, these patients were also able to lose significant amounts of body weight, reduce their waist circumference and also reduce their glycated haemoglobin level.
Fluoxetine overdose in a teenager resulting in serotonin syndrome, seizure and delayed onset rhabdomyolysis
Authors: Lee-Kelland Richard , Zehra Sabeeka , Mappa Pradeesh
Published: October 2018

A 14-year-old young adult took an overdose of 1.2 g of fluoxetine, a selective serotonin reuptake inhibitor (SSRI) that he had been prescribed for depression. He had a generalised tonic/clonic seizure at 6 hours postingestion.

After the seizure, he developed signs consistent with serotonin syndrome: fine tremor, agitation, sweating and hyperreflexia. This was followed by severe muscle pain and rhabdomyolysis with peak creatine kinase (CK) of 33 941 at 74 hours. He was managed with intravenous fluids and analgesia and discharged after 4 days, having avoided renal injury. The use of SSRI’s such as fluoxetine in teenagers has increased in recent years. While it is generally considered benign in overdose, this report illustrates the severe consequences of overdose at high quantities and discusses appropriate management in these cases. We note that in this case, there was a delayed onset of rhabdomyolysis with peak CK at 74 hours postingestion.
Severe pneumonitis refractory to steroids following anti-PD-1 immunotherapy
Authors: Andruska Neal , Mahapatra Lily , Hebbard Carleigh , Patel Priyank , Paul Vishesh
Published: October 2018

Anti-programmed death 1 (PD-1) immune checkpoint inhibitors enhance the antitumour activity of the immune system and have produced durable tumour responses in several solid tumours including non-small cell lung cancer (NSCLC). However, PD-1 inhibitors can lead to immune-related adverse events , including pneumonitis, which is typically mild, but can be severe and potentially fatal. Pneumonitis often resolves with steroids, but some cases are steroid refractory, leading to a relapsing and remitting course in milder cases or the need for salvage therapies in more severe cases. Here, we present two patients with NSCLC who developed severe pneumonitis following therapy with nivolumab and pembrolizumab. While one patient improved with steroids and infliximab, the other patient failed to respond to steroids and subsequently died. These cases demonstrate the highly variable presentation and therapeutic responses seen in patients with pneumonitis following anti-PD-1 therapy and illustrate that severe cases can often present refractory to steroid therapy.