bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of In31, a
bla
IMP
-Containing
Pseudomonas aeruginosa
Integron Phyletically Related to In5, Which Carries an Unusual Array of Gene Cassettes
Authors: Laraki Nezha , Galleni Moreno , Thamm Iris , Riccio Maria Letizia , Amicosante Gianfranco , Frère Jean-Marie , Rossolini Gian Maria 
Published: October 2018

ABSTRACT

The location and environment of the acquired
bla
IMP
gene, which encodes the IMP-1 metallo-β-lactamase, were investigated in a Japanese
Pseudomonas aeruginosa
clinical isolate (isolate 101/1477) that produced the enzyme. In this isolate,
bla
IMP
was carried on a 36-kb plasmid, and similar to the identical alleles found in
Serratia marcescens
and
Klebsiella pneumoniae
clinical isolates, it was located on a mobile gene cassette inserted into an integron. The entire structure of this integron, named In31, was determined. In31 is a class 1 element belonging to the same group of defective transposon derivatives that originated from Tn
402
-like ancestors such as In0, In2, and In5. The general structure of In31 appeared to be most closely related to that of In5 from pSCH884, suggesting a recent common phylogeny for these two elements. In In31, the
bla
IMP
cassette is the first of an array of five gene cassettes that also includes an
aacA4
cassette and three original cassettes that have never been described in other integrons. The novel cassettes carry, respectively, (i) a new chloramphenicol acetyltransferase-encoding allele of the
catB
family, (ii) a
qac
allele encoding a new member of the small multidrug resistance family of proteins, and (iii) an open reading frame encoding a protein of unknown function. All the resistance genes carried on cassettes inserted in In31 were found to be functional in decreasing the in vitro susceptibilities of host strains to the corresponding antimicrobial agents.
Biochemical Characterization of the
Pseudomonas aeruginosa
101/1477 Metallo-β-Lactamase IMP-1 Produced by
Escherichia coli
Authors: Laraki Nezha , Franceschini Nicola , Rossolini Gian Maria , Santucci Pasqualino , Meunier Cécile , de Pauw Edwin , Amicosante Gianfranco , Frère Jean Marie , Galleni Moreno 
Published: October 2018

ABSTRACT

The
bla
IMP
gene coding for the IMP-1 metallo-β-lactamase produced by a
Pseudomonas aeruginosa
clinical isolate (isolate 101/1477) was overexpressed via a T7 expression system in
Escherichia coli
BL21(DE3), and its product was purified to homogeneity with a final yield of 35 mg/liter of culture. The structural and functional properties of the enzyme purified from
E. coli
were identical to those of the enzyme produced by
P. aeruginosa
. The IMP-1 metallo-β-lactamase exhibits a broad-spectrum activity profile that includes activity against penicillins, cephalosporins, cephamycins, oxacephamycins, and carbapenems. Only monobactams escape its action. The enzyme activity was inhibited by metal chelators, of which 1,10-
o
-phenanthroline and dipicolinic acid were the most efficient. Two zinc-binding sites were found. The zinc content of the
P. aeruginosa
101/1477 metallo-β-lactamase was not pH dependent.
In Vitro Activities of Two Ketolides, HMR 3647 and HMR 3004, against Gram-Positive Bacteria
Authors: Malathum Kumthorn , Coque Teresa M. , Singh Kavindra V. , Murray Barbara E. 
Published: October 2018

ABSTRACT

The in vitro activities of two new ketolides, HMR 3647 and HMR 3004, were tested by the agar dilution method against 280 strains of gram-positive bacteria with different antibiotic susceptibility profiles, including
Staphylococcus aureus
,
Enterococcus faecalis
,
Enterococcus faecium
,
Streptococcus
spp. (group A streptococci, group B streptococci,
Streptococcus pneumoniae
, and alpha-hemolytic streptococci). Seventeen erythromycin-susceptible (Em
s
), methicillin-susceptible
S. aureus
strains were found to have HMR 3647 and HMR 3004 MICs 4- to 16-fold lower than those of erythromycin (MIC at which 50% of isolates were inhibited [MIC
50
] [HMR 3647 and HMR 3004], 0.03 μg/ml; range, 0.03 to 0.06 μg/ml; MIC
50
[erythromycin], 0.25 μg/ml; range, 0.25 to 0.5 μg/ml). All methicillin-resistant
S. aureus
strains tested were resistant to erythromycin and had HMR 3647 and HMR 3004 MICs of >64 μg/ml. The ketolides were slightly more active against
E. faecalis
than against
E. faecium
, and MICs for individual strains varied with erythromycin susceptibility. The MIC
50
s of HMR 3647 and HMR 3004 against Em
s
enterococci (MIC ≤ 0.5 μg/ml) and those enterococcal isolates with erythromycin MICs of 1 to 16 μg/ml were 0.015 μg/ml.
E. faecalis
strains that had erythromycin MICs of 128 to >512 μg/ml showed HMR 3647 MICs in the range of 0.03 to 16 μg/ml and HMR 3004 MICs in the range of 0.03 to 64 μg/ml. In the group of
E. faecium
strains for which MICs of erythromycin were ≥512 μg/ml, MICs of both ketolides were in the range of 1 to 64 μg/ml, with almost all isolates showing ketolide MICs of ≤16 μg/ml. The ketolides were also more active than erythromycin against group A streptococci, group B streptococci,
S. pneumoniae
, rhodococci, leuconostocs, pediococci, lactobacilli, and diphtheroids. Time-kill studies showed bactericidal activity against one strain of
S. aureus
among the four strains tested. The increased activity of ketolides against gram-positive bacteria suggests that further study of these agents for possible efficacy against infections caused by these bacteria is warranted.
Presence of
mefA
and
mefE
Genes in
Streptococcus agalactiae
Authors: Arpin C. , Daube H. , Tessier F. , Quentin C. 
Published: October 2018

ABSTRACT

Eighteen unrelated clinical isolates of
Streptococcus agalactiae
with the M phenotype harbored an
mef
gene. DNA sequencing showed that one of nine strains contained
mefA
(producing one amino acid substitution), whereas the remaining eight carried
mefE
(identity, 100%). Restriction analysis of PCR products indicated that the nine other strains also contained
mefE
.
Alterations in GyrA and ParC Associated with Fluoroquinolone Resistance in
Enterococcus faecium
Authors: el Amin Nagwa , Jalal Shah , Wretlind Bengt 
Published: October 2018

ABSTRACT

High-level quinolone resistance in
Enterococcus faecium
was associated with mutations in both
gyrA
and
parC
genes in 10 of 11 resistant strains. One low-level resistant strain without such mutations may instead possess an efflux mechanism or alterations in the other subunits of the gyrase or topoisomerase IV genes. These findings are similar to those for other gram-positive bacteria, such as
Enterococcus faecalis
.
Trovafloxacin in Combination with Vancomycin against Penicillin-Resistant Pneumococci in the Rabbit Meningitis Model
Authors: Rodoni Dina , Hänni Fränzi , Gerber Cynthia M. , Cottagnoud Marianne , Neftel Klaus , Täuber Martin G. , Cottagnoud Philippe 
Published: October 2018

ABSTRACT

Trovafloxacin, a new fluoroquinolone, produced bactericidal activity (−0.33 ± 0.13 Δlog
10
CFU/ml · h; intravenously [i.v.] administered dose, 15 mg/kg) comparable to that of vancomycin (−0.39 ± 0.18 Δlog
10
CFU/ml · h; i.v. administered dose, 20 mg/kg) in the treatment of experimental meningitis in rabbits due to a pneumococcal strain highly resistant to penicillin (MIC of penicillin G, 4 μg/ml). The combination of both drugs significantly increased (
P
< 0.05) the killing rate (−0.60 ± 0.23 Δlog
10
CFU/ml · h) compared to that produced by either monotherapy. These results were also confirmed in vitro.
Effect of 3-Hydroxyphthaloyl-β-Lactoglobulin on Vaginal Transmission of Simian Immunodeficiency Virus in Rhesus Monkeys
Authors: Wyand Michael S. , Manson Kelledy H. , Miller Christopher J. , Neurath A. Robert 
Published: October 2018

ABSTRACT

Heterosexual transmission of human immunodeficiency virus type 1 (HIV-1) is the major cause of the ongoing AIDS epidemic. Application of chemical barrier methods is expected to contribute to the worldwide control of this epidemic. Bovine β-lactoglobulin modified by 3-hydroxyphthalic anhydride (3-hydroxyphthaloyl-β-lactoglobulin [3HP-β-LG]) was shown to inhibit HIV-1, HIV-2, simian immunodeficiency virus (SIV), herpes simplex virus type 1 and 2, and
Chlamydia trachomatis
infection in vitro. Here, we show that 3HP-β-LG not formulated into any vehicle protected three of six rhesus monkeys against vaginal infection by SIV. Incorporation of the compound into an appropriate vehicle is expected to increase the degree of protection. 3HP-β-LG may be effective as a vaginal inhibitor of HIV-1 infection in humans.
Growth in the Presence of Salicylate Increases Fluoroquinolone Resistance in
Staphylococcus aureus
Authors: Gustafson John E. , Candelaria Pierre V. , Fisher Scott A. , Goodridge Jodie P. , Lichocik Tanya M. , McWilliams Tracy M. , Price Christopher T. D. , O’Brien Frances G. , Grubb Warren B. 
Published: October 2018

ABSTRACT

Salicylate and acetylsalicylate slightly increased fluoroquinolone resistance in ciprofloxacin-susceptible and -resistant
Staphylococcus aureus
. Salicylate allowed a greater number of cells from ciprofloxacin-susceptible and -resistant strains to survive on high fluoroquinolone concentrations. Salicylate also increased the frequency with which a susceptible strain mutated to become more resistant to ciprofloxacin.
Thiolated Recombinant Human Tumor Necrosis Factor-Alpha Protects againstPlasmodium bergheiK173-Induced Experimental Cerebral Malaria in Mice
Authors: Postma Nancy S. , Hermsen Rob C. , Crommelin Daan J. A. , Eling Wijnand M. C. , Zuidema Jan 
Published: October 2018

ABSTRACTThe introduction of reactive thiol groups in recombinant human tumor necrosis factor (TNF) alpha (rhTNF-α) by the reagent succinimidyl-S-acetylthioacetate resulted in the formation of a chemically stabilized rhTNF-α trimer (rhTNFα-AT; as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis). rhTNFα-AT showed a substantially enhanced protective efficacy against the development of experimental murine cerebral malaria (ECM) after intravenous injection compared to the protective efficacy of nonmodified rhTNF-α. Administration of thiolated rhTNF-α with protected thiol groups (rhTNFα-ATA; no stabilized trimers in vitro) exhibited the same protective efficacy against ECM, while in vitro bioactivity was reduced. Parasitemia was significantly suppressed in rhTNF-treated mice that were protected against ECM but not in treated mice that developed ECM. Protection against ECM was not related to increased concentrations in plasma of soluble TNF receptor 1 and 2 directly after injection or at the moment of development of ECM in nontreated mice. The results indicate that thiolation of rhTNF-α leads to the formation of stable trimers with increased potential in vivo.
Distribution of Genes Encoding Resistance to Macrolides, Lincosamides, and Streptogramins among Staphylococci
Authors: Lina Gerard , Quaglia Alain , Reverdy Marie-Elisabeth , Leclercq Roland , Vandenesch François , Etienne Jerome 
Published: October 2018

ABSTRACT

The relative frequency of 10 determinants of resistance to macrolides, lincosamides, and streptogramins was investigated by PCR in a series of 294 macrolide-, lincosamide-, and/or streptogramin-resistant clinical isolates of
Staphylococcus aureus
and coagulase-negative staphylococci isolated in 1995 from 32 French hospitals. Resistance was mainly due to the presence of
ermA
or
ermC
genes, which were detected in 259 strains (88%), in particular those resistant to methicillin (78% of the strains). Macrolide resistance due to
msrA
was more prevalent in coagulase-negative staphylococci (14.6%) than in
S. aureus
(2.1%). Genes related to
linA/linA′
and conferring resistance to lincomycin were detected in one strain of
S. aureus
and seven strains of coagulase-negative staphylococci. Resistance to pristinamycin and quinupristin-dalfopristin was phenotypically detected in 10 strains of
S. aureus
and in three strains of coagulase-negative staphylococci; it was always associated with resistance to type A streptogramins encoded by
vat
or
vatB
genes and occurred in association with
erm
genes. The
vga
gene conferring decreased susceptibility to type A streptogramins was present alone in three strains of coagulase-negative staphylococci and in combination with
erm
genes in 10 strains of coagulase-negative staphylococci. A combination of
vga-vgb-vat
and
ermA
genes was found in a single strain of
S. epidermidis
.
Pharmacokinetics of Gatifloxacin and Interaction with an Antacid Containing Aluminum and Magnesium
Authors: Lober Silke , Ziege Susanne , Rau Margot , Schreiber Gabriele , Mignot Alain , Koeppe Peter , Lode Hartmut 
Published: October 2018

ABSTRACT

The pharmacokinetics of gatifloxacin (400 mg orally) and the influence of the antacid aluminum magnesium hydroxide (20 ml of Maalox 70) on the bioavailability of gatifloxacin in 24 healthy volunteers were assessed. In an open, randomized, six-period crossover study, the volunteers received either gatifloxacin alone (treatments A and D); aluminum magnesium hydroxide concomitant with gatifloxacin (treatment C); or aluminum magnesium hydroxide 2 h before (treatment B), 2 h after (treatment E), or 4 h after gatifloxacin administration (treatment F). Gatifloxacin concentrations were measured by a validated bioassay and high-performance liquid chromatography. Pharmacokinetics of a single 400-mg dose of gatifloxacin alone were characterized as follows (mean ± standard deviation): peak concentration (
C
max
), 3.8 ± 0.5 (treatment A) and 3.4 ± 0.9 (treatment D) μg/ml; time to
C
max
, 1.4 ± 0.8 (treatment A) and 1.7 ± 0.7 (treatment D) h; area under the curve from time zero to infinity (AUC
0–∞
), 33.5 ± 5.9 (treatment A) and 31.4 ± 3.4 (treatment D) μg · h/ml; urine recovery, (83 ± 6)% (treatment A) and (84 ± 8)% (treatment D). Comparison of the results obtained by bioassay showed a good correlation. Aluminum magnesium hydroxide administration 2 h before (treatment B) or concomitant with (treatment C) gatifloxacin decreased the
C
max
by 45% (2.1 ± 1.2 μg/ml) or even 68% (1.2 ± 0.4 μg/ml) highly significantly (
P
< 0.01). AUC
0–∞
was significantly reduced from 33.5 ± 5.9 to 19.4 ± 6.9 μg · h/ml (by 42%) or even to 11.9 ± 3.3 μg · h/ml (by 64%) (
P
< 0.01). If aluminum magnesium hydroxide was given 2 h after gatifloxacin (treatment E), there was no significant reduction of concentration in serum but AUC
0–∞
was significantly reduced from 31.4 ± 3.4 to 25.9 ± 5.3 μg · h/ml (18%) (
P
< 0.01). Aluminum magnesium hydroxide given 4 h after gatifloxacin (treatment F) showed no influence on the gatifloxacin pharmacokinetics. Therefore, the optimal time between gatifloxacin application and the intake of an aluminum-containing antacid should be 4 h.
From
vanA Enterococcus hirae
to
vanA Enterococcus faecium
: a Study of Feed Supplementation with Avoparcin and Tylosin in Young Chickens
Authors: Robredo Beatriz , Singh Kavindra V. , Baquero Fernando , Murray Barbara E. , Torres Carmen 
Published: October 2018

ABSTRACT

Fifteen newborn chickens were isolated in separate cages after 1 month of living together, divided into three groups, and challenged for 5 weeks with seed food which either was supplemented with avoparcin (10 mg/kg of animal food) or tylosin (40 mg/kg) or was nonsupplemented. At 9 weeks of age and after the 5-week challenge, all chickens received nonsupplemented feed for 4 additional weeks. At 4, 9, and 13 weeks of life, feces were collected and inoculated on M-
Enterococcus
agar plates with and without vancomycin (4 μg/ml).
vanA
-containing
Enterococcus hirae
was isolated from 11 of 15 chickens before antibiotic challenge, without detection of vancomycin-resistant
Enterococcus faecium
. At 9 weeks of age and after the 5-week avoparcin challenge,
vanA E. hirae
strains were no longer detected, but five of five chickens now had
vanA E. faecium
. At a lower frequency,
vanA E. faecium
had also displaced
vanA E. hirae
in both the tylosin group (one of four chickens) and the control group (two of five chickens). One month after avoparcin discontinuation, the number of chickens colonized with
vanA E. faecium
decreased from five to one. All
vanA
-containing
E. hirae
strains detected in the first month of life and most of the
vanA
-containing
E. faecium
strains detected in the second month of life showed identical
Apa
I and
Sma
I restriction patterns, respectively, when analyzed by pulsed-field gel electrophoresis. All
vanA E. hirae
isolates transferred glycopeptide and macrolide resistance to
Enterococcus faecalis
JH2-2 in vitro; the level of glycopeptide resistance was higher in the transconjugants than in the donor
E. hirae
strains. These data suggest that
E. hirae
may be a significant source of
vanA
determinants with the potential of transfer to other enterococcal species from humans or animals.
Lack of Effect of Zafirlukast on the Pharmacokinetics of Azithromycin, Clarithromycin, and 14-Hydroxyclarithromycin in Healthy Volunteers
Authors: Garey Kevin W. , Peloquin Charles A. , Godo Paul G. , Nafziger Anne N. , Amsden Guy W. 
Published: October 2018

ABSTRACT
This randomized, open-label, crossover study was conducted to investigate whether the coadministration of zafirlukast would affect the pharmacokinetics of azithromycin, clarithromycin, or 14-hydroxyclarithromycin (14-OHC). Twelve healthy subjects (six males and six females) received single 500-mg doses of azithromycin and clarithromycin with and without zafirlukast given to a steady-state concentration. Blood was collected prior to all macrolide doses and for 3 and 10 days after each clarithromycin and azithromycin dose, respectively. Serum was assayed for azithromycin, clarithromycin, and 14-OHC concentrations by validated high-performance liquid chromatography assay systems. Data analyses were done by noncompartmental and nonparametric methods. Analysis of the patients indicated that the addition of steady-state concentrations of zafirlukast did not significantly alter the pharmacokinetic parameters of or overall exposure (based on the area under the concentration-time curve) to azithromycin, clarithromycin, and 14-OHC. While zafirlukast is a known inhibitor of CYP3A4, it does not appear to exert a clinically or statistically significant pharmacokinetic effect on azithromycin, clarithromycin, or 14-OHC.
In Vitro Activities of the Potent, Broad-Spectrum Carbapenem MK-0826 (L-749,345) against Broad-Spectrum β-Lactamase-and Extended-Spectrum β-Lactamase-Producing
Klebsiella pneumoniae
and
Escherichia coli
Clinical Isolates
Authors: Kohler Joyce , Dorso Karen L. , Young Katherine , Hammond Gail G. , Rosen Hugh , Kropp Helmut , Silver Lynn L. 
Published: October 2018

ABSTRACT

An important mechanism of bacterial resistance to β-lactam antibiotics is inactivation by β-lactam-hydrolyzing enzymes (β-lactamases). The evolution of the extended-spectrum β-lactamases (ESBLs) is associated with extensive use of β-lactam antibiotics, particularly cephalosporins, and is a serious threat to therapeutic efficacy. ESBLs and broad-spectrum β-lactamases (BDSBLs) are plasmid-mediated class A enzymes produced by gram-negative pathogens, principally
Escherichia coli
and
Klebsiella pneumoniae
. MK-0826 was highly potent against all ESBL- and BDSBL-producing
K. pneumoniae
and
E. coli
clinical isolates tested (MIC range, 0.008 to 0.12 μg/ml). In
E. coli
, this activity was associated with high-affinity binding to penicillin-binding proteins 2 and 3. When the inoculum level was increased 10-fold, increasing the amount of β-lactamase present, the MK-0826 MIC range increased to 0.008 to 1 μg/ml. By comparison, similar observations were made with meropenem while imipenem MICs were usually less affected. Not surprisingly, MIC increases with noncarbapenem β-lactams were generally substantially greater, resulting in resistance in many cases.
E. coli
strains that produce chromosomal (Bush group 1) β-lactamase served as controls. All three carbapenems were subject to an inoculum effect with the majority of the BDSBL- and ESBL-producers but not the Bush group 1 strains, implying some effect of the plasmid-borne enzymes on potency. Importantly, MK-0826 MICs remained at or below 1 μg/ml under all test conditions.
Diversity of Substitutions within or Adjacent to Conserved Amino Acid Motifs of Penicillin-Binding Protein 2X in Cephalosporin-Resistant
Streptococcus pneumoniae
Isolates
Authors: Asahi Yasuko , Takeuchi Yasuo , Ubukata Kimiko 
Published: October 2018

ABSTRACT

The sequence of an approximately 1.1-kb DNA fragment of the
pbp2x
gene, which encodes the transpeptidase domain, was determined for 35 clinical isolates of
Streptococcus pneumoniae
for which the cefotaxime (CTX) MICs varied. Strains with substitutions within a conserved amino acid motif changing STMK to SAFK and a Leu-to-Val change just before the KSG motif were highly resistant to CTX (MIC, ≧2 μg/ml). Strains with substitutions adjacent to SSN or KSG motifs had low-level resistance. The amino acid substitutions were plotted on the three-dimensional crystallographic structure of the transpeptidase domain of PBP2X. Transformants containing
pbp2x
from strains with high-level CTX resistance increased the CTX MIC from 0.016 μg/ml to 0.5 to 1.0 μg/ml.
Improved Derivatives of Bactenecin, a Cyclic Dodecameric Antimicrobial Cationic Peptide
Authors: Wu Manhong , Hancock Robert E. W. 
Published: October 2018

ABSTRACT
Both linear and cyclic derivatives of the cyclic 12-amino-acid antimicrobial peptide bactenecin were designed based on optimization of amphipathicity and charge location. In general, increasing the number of positive charges at the N and C termini and adding an extra tryptophan residue in the loop not only increased the activities against both gram-positive and gram-negative bacteria but also broadened the antimicrobial spectrum.
In Vitro Activities of Antibiotics Alone and in Combination against
Brucella melitensis
at Neutral and Acidic pHs
Authors: Akova Murat , Gür Deniz , Livermore David M. , Kocagöz Tanil , Akalin H. Erdal 
Published: October 2018

ABSTRACT

Brucellae survive acidic pHs in phagolysosomes. Azithromycin, streptomycin, and quinolones were active against
Brucella melitensis
at pH 7.0 but not at pH 5.0; rifampin and doxycycline retained activity at pH 5.0. Regardless of pH, azithromycin-rifampin and ofloxacin-rifampin showed less synergy than established streptomycin-doxycycline and rifampin-doxycycline combinations.
The Trailing End Point Phenotype in Antifungal Susceptibility Testing Is pH Dependent
Authors: Marr Kieren A. , Rustad Tige R. , Rex John H. , White Theodore C. 
Published: October 2018

ABSTRACT

The interpretation of end points in azole antifungal drug susceptibility testing is problematic, in part due to incomplete growth inhibition of
Candida
species. Such trailing growth can cause the MICs of fluconazole for some isolates to be low (<1 μg/ml) after 24 h of growth but much higher (>64 μg/ml) after 48 h. Isolates having this type of growth have been described as having a low-high phenotype. Although these isolates would be considered resistant by current National Committee of Clinical Laboratory Standards definitions, growing evidence suggests that they are susceptible in vivo. To further characterize these isolates in vitro, microdilution susceptibility testing comparing the complex defined medium RPMI 1640 to a defined minimal medium (yeast nitrogen broth) was performed. Isolates having trailing growth in MOPS (morpholinepropanesulfonic acid)-buffered RPMI 1640 (pH 7.0) were found to have clear end points in the minimal medium at its native pH of 4.5. The pH of the medium influenced the low-high phenotype, as these same isolates trailed in minimal medium adjusted to a pH of ≥6.0 but did not trail in RPMI 1640 adjusted to a pH of ≤5.0. This pH effect was independent of the medium buffering capacity, as trailing was decreased in both minimal medium and RPMI 1640 (pH 4.5) buffered in citrate. Adjustment in the pH of MOPS-buffered RPMI 1640 reduced trailing in multiple strains of
Candida albicans
without affecting the MICs for isolates having known susceptible (low-low) and resistant (high-high) phenotypes. Adjustment of the medium pH could be considered to eliminate trailing in azole drug susceptibility testing.