bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Activities of Peptidic Prodrugs of Novel Aminomethyl Tetrahydrofuranyl-1β-Methylcarbapenems
Authors: Weiss William J. , Mikels Susan M. , Petersen Peter J. , Jacobus Nilda V. , Bitha Panayota , Lin Yang-I. , Testa Raymond T.
Published: October 2018

A series of novel aminomethyl tetrahydrofuranyl (THF)-1β-methylcarbapenems which have excellent broad-spectrum antibacterial activities exhibit modest efficacies against acute lethal infections (3.8 mg/kg of body weight againstEscherichia coliand 0.9 mg/kg againstStaphylococcus aureus) in mice when they are administered orally. In an effort to improve the efficacies of orally administered drugs through enhanced absorption by making use of a peptide-mediated transport system, several different amino acids were added at the aminomethyl THF side chains of the carbapenem molecules. The resulting peptidic prodrugs withl-amino acids demonstrated improved efficacy after oral administration, while thedforms were less active than the parent molecules. After oral administration increased (3 to 10 times) efficacy was exhibited with the alanine-, valine-, isoleucine-, and phenylalanine-substituted prodrugs against acute lethal infections in mice. Median effective doses (ED50s) of <1 mg/kg against infections caused byS. aureus,E. coli,Enterobacter cloacae, or penicillin-susceptibleStreptococcus pneumoniaewere obtained after the administration of single oral doses. Several of the peptidic prodrugs were efficacious againstMorganella morganii,Serratia marcescens, penicillin-resistantS. pneumoniae, extended-spectrum β-lactamase-producingKlebsiella pneumoniae, andE. coliinfections, with ED50s of 1 to 14 mg/kg by oral administration compared with ED50s of 14 to >32 mg/kg for the parent molecules. In general, the parent molecules demonstrated greater efficacy than the prodrugs against these same infections when the drugs were administered by the subcutaneous route. The parent molecule was detectable in the sera of mice after oral administration of the peptidic prodrugs.
In Vitro and In Vivo Activities of NS-718, a New Lipid Nanosphere Incorporating Amphotericin B, against
Aspergillus fumigatus
Authors: Otsubo Takakazu , Maesaki Shigefumi , Hossain Mohammad Ashraf , Yamamoto Yoshihiro , Tomono Kazunori , Tashiro Takayoshi , Seki Junzo , Tomii Yoshifumi , Sonoke Satoru , Kohno Shigeru
Published: October 2018

We evaluated the in vitro and in vivo potencies of a new lipid nanosphere that incorporates amphotericin B (AmB), NS-718, against
Aspergillus fumigatus
. The in vitro activity of NS-718 (the MIC at which 90% of strains are inhibited [MIC
90
], 0.25 μg/ml) against 18 isolates of
A. fumigatus
was similar to that of deoxycholate AmB (D-AmB; Fungizone; MIC
90
, 0.25 μg/ml), but NS-718 was more potent than liposomal AmB (L-AmB; AmBisome; MIC
90
, 1.0 μg/ml). The in vivo efficacy of NS-718 in a rat model of invasive pulmonary aspergillosis was compared with those of D-AmB and L-AmB. A low dose (1 mg/kg of body weight) of L-AmB was ineffective (survival rate, 0%), although equivalent doses of D-AmB and NS-718 were more effective (survival rate, 17%). However, a higher dose of NS-718 (3 mg/kg) was more effective (survival rate, 100%) than equivalent doses of D-AmB and L-AmB (survival rate, 0%). To explain these differences, pharmacokinetic studies showed higher concentrations of AmB in the plasma of rats treated with NS-718 than in the plasma of those treated with D-AmB. Our results suggest that NS-718, a new preparation of AmB, is a promising antifungal agent with activity against pulmonary aspergillosis.
Two-Step Acquisition of Resistance to the Teicoplanin-Gentamicin Combination by VanB-Type
Enterococcus faecalis
In Vitro and in Experimental Endocarditis
Authors: Lefort Agnès , Baptista Marina , Fantin Bruno , Depardieu Florence , Arthur Michel , Carbon Claude , Courvalin Patrice
Published: October 2018

The activity of vancomycin and teicoplanin combined with gentamicin was investigated in vitro against strains of
Enterococcus faecalis
resistant to vancomycin and susceptible to teicoplanin (VanB type) and against mutants that had acquired resistance to teicoplanin by three different mechanisms. In vitro, gentamicin selected mutants with two- to sixfold increases in the level of resistance to this antibiotic at frequencies of 10
−6
to 10
−7
. Teicoplanin selected teicoplanin-resistant mutants at similar frequencies. Both mutations were required to abolish the activity of the gentamicin-teicoplanin combination. As expected, simultaneous acquisition of the two types of mutations was not observed. In therapy with gentamicin or teicoplanin alone, each selected mutants in three of seven rabbits with aortic endocarditis due to VanB-type
E. faecalis
BM4275. The vancomycin-gentamicin combination selected mutants that were resistant to gentamicin and to the combination. In contrast, the teicoplanin-gentamicin regimen prevented the emergence of mutants resistant to one or both components of the combination. These results suggest that two mutations are also required to suppress the in vivo activity of the teicoplanin-gentamicin combination.
Effect of Fasting on Temporal Variation in the Nephrotoxicity of Amphotericin B in Rats
Authors: LeBrun Michel , Grenier Louis , Bergeron Michel G. , Thibault Louise , Labrecque Gaston , Beauchamp Denis
Published: October 2018

Evidence for temporal variation in the nephrotoxicity of amphotericin B was recently reported in experimental animals. The role of food in these variations was determined by studying the effect of a short fasting period on the temporal variation in the renal toxicity of amphotericin B. Twenty-eight normally fed and 28 fasted female Sprague-Dawley rats were used. Food was available ad libitum to the fed rats, while the fasted animals were fasted 12 h before and 24 h after amphotericin B injection to minimize stress for the animals. Water was available ad libitum to both groups of rats, which were maintained on a 14-h light, 10-h dark regimen (light on at 0600 h). Renal toxicity was determined by comparing the levels of excretion of renal enzyme and the serum creatinine and blood urea nitrogen (BUN) levels at the time of the maximal (0700 h) or the minimal (1900 h) nephrotoxicity after the intraperitoneal administration of a single dose of dextrose (5%; control group) or amphotericin B (50 mg/kg of body weight; treated group) to the rats. The nephrotoxicities obtained after amphotericin B administration at both times of day were compared to the nephrotoxicities observed for time-matched controls. In fed animals, the 24-h urinary excretion of
N
-acetyl-β-
d
-glucosaminidase and β-galactosidase was significantly higher when amphotericin B was injected at 0700 and 1900 h. The excretion of these two enzymes was reduced significantly (
P
< 0.05) in fasting rats, and this effect was larger at 0700 h (
P
< 0.05) than at 1900 h. The serum creatinine level was also significantly higher (
P
< 0.05) in fed animals treated at 0700 h than in fed animals treated at 1900 h. Fasting reduced significantly (
P
< 0.05) the increase in the serum creatinine level, and this effect was larger in the animals treated at 0700 h. Similar data were obtained for BUN levels. Amphotericin B accumulation was significantly higher (
P
< 0.05) in the renal cortexes of fed rats than in those of fasted animals, but there was no difference according to the time of injection. These results demonstrated that fasting reduces the nephrotoxicity of amphotericin B and that food availability is of crucial importance in the temporal variation in the renal toxicity of amphotericin B in rats.
Cloning, Expression, and Enzymatic Characterization of
Pseudomonas aeruginosa
Topoisomerase IV
Authors: Akasaka Takaaki , Onodera Yoshikuni , Tanaka Mayumi , Sato Kenichi
Published: October 2018

The topoisomerase IV subunit A gene,
parC
homolog, has been cloned and sequenced from
Pseudomonas aeruginosa
PAO1, with cDNA encoding the N-terminal region of
Escherichia coli parC
used as a probe. The homolog and its upstream gene were presumed to be
parC
and
parE
through sequence homology with the
parC
and
parE
genes of other organisms. The deduced amino acid sequence of ParC and ParE showed 33 and 32% identity with that of the
P. aeruginosa
DNA gyrase subunits, GyrA and GyrB, respectively, and 69 and 75% identity with that of
E. coli
ParC and ParE, respectively. The putative ParC and ParE proteins were overexpressed and separately purified by use of a fusion system with a maltose-binding protein, and their enzymatic properties were examined. The reconstituted enzyme had ATP-dependent decatenation activity, which is the main catalytic activity of bacterial topoisomerase IV, and relaxing activities but had no supercoiling activity. So, the cloned genes were identified as
P. aeruginosa
topoisomerase IV genes. The inhibitory effects of quinolones on the activities of topoisomerase IV and DNA gyrase were compared. The 50% inhibitory concentrations of quinolones for the decatenation activity of topoisomerase IV were from five to eight times higher than those for the supercoiling activities of
P. aeruginosa
DNA gyrase. These results confirmed that topoisomerase IV is less sensitive to fluoroquinolones than is DNA gyrase and may be a secondary target of new quinolones in wild-type
P. aeruginosa
.
Synergy of an Investigational Glycopeptide, LY333328, with Once-Daily Gentamicin against Vancomycin-Resistant
Enterococcus faecium
in a Multiple-Dose, In Vitro Pharmacodynamic Model
Authors: Zelenitsky S. A. , Booker B. , Laing N. , Karlowsky J. A. , Hoban D. J. , Zhanel G. G.
Published: October 2018

The pharmacodynamics of an investigational glycopeptide, LY333328 (LY), alone and in combination with gentamicin, against one vancomycin-susceptible and two vancomycin-resistant
Enterococcus faecium
strains were studied with a multiple-dose, in vitro pharmacodynamic model (PDM). Dose-range data for the PDM studies were obtained from static time-kill curve studies. In PDM experiments conducted over 48 h, peak LY concentrations of 0.1× and 1× the MIC every 24 h and peak gentamicin concentrations of 18 μg/ml every 24 h (Gq24h) and 6 μg/ml every 8 h (Gq8h) were studied alone and in the four possible LY-gentamicin combinations. Compared to either antibiotic alone, LY-gentamicin combination regimens produced significantly higher apparent killing rates (KRs) calculated during the initial 2 h postdosing. The mean KRs for LY or gentamicin alone versus those for the LY-gentamicin combination regimens were 0.35 ± 0.55 log
10
CFU/ml/h (95% confidence interval [CI
95%
], 0 to 0.70) and 1.46 ± 0.71 log
10
CFU/ml/h (CI
95%
, 1.01 to 1.91), respectively (
P <
0.0001). Bacterial killing at 48 h (BK
48
), which was calculated by subtracting the bacterial counts at 48 h from the initial inoculum, with a negative value indicating net growth, was also significantly greater. The mean BK
48
s were −0.69 ± 0.44 log
10
CFU/ml (CI
95%
, −0.41 to −0.97) and 3.72 ± 2.28 log
10
CFU/ml (CI
95%
, 2.28 to 5.17) for LY or gentamicin alone versus LY-gentamicin combination regimens, respectively (
P
< 0.0001). None of the 12 regimens with LY or gentamicin alone but 75% (9 of 12) of the LY-gentamicin combination regimens were bactericidal. Eighty-three percent (10 of 12) of the LY-gentamicin combination regimens also demonstrated synergy. No significant differences between the pharmacodynamics of LY-gentamicin combination regimens containing Gq24h versus those containing Gq8h were detected.
Safety and Pharmacokinetics of Abacavir (1592U89) following Oral Administration of Escalating Single Doses in Human Immunodeficiency Virus Type 1-Infected Adults
Authors: Kumar Princy N. , Sweet Donna E. , McDowell James A. , Symonds William , Lou Yu , Hetherington Seth , LaFon Stephen
Published: October 2018

Abacavir (1592U89) is a nucleoside analog reverse transcriptase inhibitor that has been demonstrated to have selective activity against human immunodeficiency virus (HIV) in vitro and favorable safety profiles in mice and monkeys. A phase I study was conducted to evaluate the safety and pharmacokinetics of abacavir following oral administration of single escalating doses (100, 300, 600, 900, and 1,200 mg) to HIV-infected adults. In this double-blind, placebo-controlled study, subjects with baseline CD4
+
cell counts ranging from <50 to 713 cells per mm
3
(median, 315 cells per mm
3
) were randomly assigned to receive abacavir (
n
= 12) or placebo (
n
= 6). The bioavailability of the caplet formulation relative to that of the oral solution was also assessed with the 300-mg dose. Abacavir was well tolerated by all subjects; mild to moderate asthenia, abdominal pain, headache, diarrhea, and dyspepsia were the most frequently reported adverse events, and these were not dose related. No significant clinical or laboratory abnormalities were observed throughout the study. All doses resulted in mean abacavir concentrations in plasma that exceeded the mean 50% inhibitory concentration (IC
50
) for clinical HIV isolates in vitro (0.07 μg/ml) for almost 3 h. Abacavir was rapidly absorbed following oral administration, with the time to the peak concentration in plasma occurring at 1.0 to 1.7 h postdosing. Mean maximum concentrations in plasma (
C
max
) and the area under the plasma concentration-time curve from time zero to infinity (AUC
0–∞
) increased slightly more than proportionally from 100 to 600 mg (from 0.6 to 4.7 μg/ml for
C
max
; from 1.0 to 15.7 μg · h/ml for AUC
0–∞
) but increased proportionally from 600 to 1,200 mg (from 4.7 to 9.6 μg/ml for
C
max
; from 15.7 to 32.8 μg · h/ml for AUC
0–∞
). The elimination of abacavir from plasma was rapid, with an apparent elimination half-life of 0.9 to 1.7 h. Abacavir was well absorbed, with a relative bioavailability of the caplet formulation of 96% versus that of an oral solution (drug substance in water). In conclusion, this study showed that abacavir is safe and is well tolerated by HIV-infected subjects and demonstrated predictable pharmacokinetic characteristics when it was administered as single oral doses ranging from 100 to 1,200 mg.
Use of an Isogenic
Escherichia coli
Panel To Design Tests for Discrimination of β-Lactamase Functional Groups of
Enterobacteriaceae
Authors: Ehrhardt Anton F. , Sanders Christine C. , Moland Ellen S.
Published: October 2018

A study was designed to determine if an isogenic panel of
Escherichia coli
strains containing many different β-lactamases could be used for the preliminary screening of a large number of β-lactam agents to identify which might be most useful in the development of a definitive test for specific β-lactamases found among the members of family
Enterobacteriaceae
. The susceptibilities of 46 strains, comprising the isogenic panel, to expanded-spectrum cephalosporins, cephamycins, and aztreonam were determined in the presence and absence of β-lactamase inhibitors in broth microdilution tests. The results indicated that strains producing extended-spectrum β-lactamases (ESBLs) could be distinguished from strains producing other Bush-Jacoby-Medeiros functional group 2 or group 1 β-lactamases. For strains producing group 1 β-lactamases, cefpodoxime and ceftazidime MICs were ≥4 μg/ml and addition of clavulanate did not reduce the MICs more than fourfold. For strains producing group 2 enzymes other than ESBLs, cefpodoxime and ceftazidime MICs were ≤2 μg/ml. With a single exception (ceftazidime for the strain producing SHV-3), among strains producing ESBLs, cefpodoxime and ceftazidime MICs were ≥4 μg/ml and addition of clavulanate reduced the MICs by more than eightfold. Cephamycins could also be used to discriminate between strains producing group 1 β-lactamases and ESBLs, since only the former required cefotetan concentrations as high as 8 μg/ml or cefoxitin concentrations of >16 μg/ml for inhibition. Other cephalosporins provided some discrimination between the various β-lactamase producers, although they were not as reliable as either cefpodoxime or ceftazidime. These results indicate the utility of an isogenic panel for identification of candidate drugs among many for further testing with clinical isolates of the family
Enterobacteriaceae
to determine the best agents for detection of specific β-lactamases in this family.
Pharmacodynamic Comparisons of Levofloxacin, Ciprofloxacin, and Ampicillin against
Streptococcus pneumoniae
in an In Vitro Model of Infection
Authors: Lacy Melinda K. , Lu Wen , Xu Xiaowei , Tessier Pamela R. , Nicolau David P. , Quintiliani Richard , Nightingale Charles H.
Published: October 2018

The increasing frequency of penicillin-resistant pneumococcus continues to be of concern throughout the world. Newer fluoroquinolone antibiotics, such as levofloxacin, have shown enhanced in vitro activity against
Streptococcus pneumoniae
. In this study, the bactericidal characteristics and pharmacodynamic profiles of levofloxacin, ciprofloxacin, and ampicillin against four isolates of
S. pneumoniae
were compared by using an in vitro model of infection. Standard antibiotic dosing regimens which simulated the pharmacokinetic profile observed in humans were used. Control and treatment models were sampled for bacterial CFU per milliliter over the duration of each 24- or 48-h experiment. In addition, treatment models were sampled for MIC determinations and drug concentration. Regrowth of all isolates as well as an increase in MICs throughout the study period was observed in the ciprofloxacin experiments. A limited amount of regrowth was noted during levofloxacin therapy for one isolate; however, no change in MIC was detected for any isolate. Ampicillin showed rapid and sustained bactericidal activity against all isolates. In this study, ratios of effective fluoroquinolone area under the concentration-time curve (AUC):MIC values ranged from 30 to 55. Levofloxacin, owing to its larger AUC
0–24
values, has excellent and sustained activity against different pneumococcal strains superior to that of ciprofloxacin.
Evaluation of Bactericidal Activities of LY333328, Vancomycin, Teicoplanin, Ampicillin-Sulbactam, Trovafloxacin, and RP59500 Alone or in Combination with Rifampin or Gentamicin against Different Strains of Vancomycin-Intermediate
Staphylococcus aureus
by Time-Kill Curve Methods
Authors: Hershberger Ellie , Aeschlimann Jeffrey R. , Moldovan Tabitha , Rybak Michael J.
Published: October 2018

This in vitro study evaluated the activities of vancomycin, LY333328, and teicoplanin alone and in combination with gentamicin, rifampin, and RP59500 against
Staphylococcus aureus
isolates with intermediate susceptibilities to vancomycin. Ampicillin-sulbactam and trovafloxacin were also evaluated. LY333328 and ampicillin-sulbactam resulted in bactericidal activity against all isolates. The combination of gentamicin with glycopeptides showed synergistic activity, while rifampin had no added benefit.
Effects of Azole Antifungal Drugs on the Transition from Yeast Cells to Hyphae in Susceptible and Resistant Isolates of the Pathogenic Yeast
Candida albicans
Authors: Ha Kien C. , White Theodore C.
Published: October 2018

Oral infections caused by the yeast
Candida albicans
are some of the most frequent and earliest opportunistic infections in human immunodeficiency virus-infected patients. The widespread use of azole antifungal drugs has led to the development of drug resistance, creating a major problem in the treatment of yeast infections in AIDS patients and other immunocompromised individuals. Several molecular mechanisms that contribute to drug resistance have been identified. In
C. albicans
, the ability to morphologically switch from yeast cells (blastospores) to filamentous forms (hyphae) is an important virulence factor which contributes to the dissemination of
Candida
in host tissues and which promotes infection and invasion. A positive correlation between the level of antifungal drug resistance and the ability to form hyphae in the presence of azole drugs has been identified. Under hypha-inducing conditions in the presence of an azole drug, resistant clinical isolates form hyphae, while susceptible yeast isolates do not. This correlation is observed in a random sample from a population of susceptible and resistant isolates and is independent of the mechanisms of resistance.
35
S-methionine incorporation suggests that growth inhibition is not sufficient to explain the inhibition of hyphal formation, but it may contribute to this inhibition.
Impact ofgyrAandparCMutations on Quinolone Resistance, Doubling Time, and Supercoiling Degree ofEscherichia coli
Authors: Bagel Simone , Hüllen Volker , Wiedemann Bernd , Heisig Peter
Published: October 2018

Isogenic mutants derived from quinolone-susceptible isolate WT by introducinggyrA(S83L, D87G) andparC(S80I, E84K) mutations associated with quinolone resistance were characterized with respect to quinolone resistance, growth rate, and degree of global supercoiling. The latter was determined by use of a pair of reporter plasmids carrying supercoiling-dependent promoters pgyrAand ptopA, respectively, transcriptionally fused to the reporter geneblacoding for TEM-1 β-lactamase. The quotient (Qsc) of the β-lactamase specific activity determined for a mutant carrying either plasmid was taken as a measure of the degree of global supercoiling. These Qsc data were comparable to results obtained from the separation of topoisomers of plasmid pBR322 on chloroquine-containing agarose gels and indicate a reduced degree of negative supercoiling in resistant mutants relative to the parent, WT. The S83L mutation ingyrAhad the strongest influence on quinolone resistance while leaving other parameters nearly unaffected. ThegyrAdouble mutation (S83L plus D87G) had an effect on quinolone resistance similar to that of a single mutation. Phenotypic expression of theparCmutation (S80I) was dependent on the presence of at least onegyrAmutation. Expression of high-level fluoroquinolone resistance (ciprofloxacin MIC, >4 μg/ml) required a combination of thegyrAdouble mutation and oneparCmutation (S80I or E84K). Such mutants showed considerable alterations of growth rate, global supercoiling, or both. Introduction of aparCmutation affected neither the doubling time nor the degree of supercoiling, while the presence of thegyrAD87G mutation was associated with a significant reduction in the degree of DNA supercoiling.
Lipopolyamines: Novel Antiendotoxin Compounds That Reduce Mortality in Experimental Sepsis Caused by Gram-Negative Bacteria
Authors: David Sunil A. , Silverstein Richard , Amura Claudia R. , Kielian Tammy , Morrison David C.
Published: October 2018

The interactions of lipopolyamines, a class of structurally unique compounds currently being used as transfection (lipofection) agents, with lipopolysaccharide (LPS) have been characterized. Our studies have demonstrated that 1,3-di-oleoyloxy-2-(6-carboxyspermyl)-propylamide), available commercially as DOSPER, binds to purified LPS with an affinity of about 1/10 that of polymyxin B. This essentially nontoxic compound inhibits, in a dose-dependent manner, LPS-induced activation of theLimulusclotting cascade and the production of tumor necrosis factor alpha (TNF-α) interleukin-6 (IL-6), and nitric oxide from LPS-stimulated J774.A1 cells, a murine macrophage-like cell line. Cytokine inhibition is paralleled by decreased steady-state levels of TNF-α and IL-6 mRNA and inhibits the nuclear translocation of nuclear factor kappa B. These findings suggest that the lipopolyamine compound sequesters LPS, thereby blocking downstream cellular activation events that lead to the production of proinflammatory mediators. Administration of DOSPER tod-galactosamine-sensitized mice challenged either with LPS or withEscherichia coliorganisms provided significant protection against lethality both with and without antibiotic chemotherapy. Partial protection is evident in LPS-challenged mice treated with DOSPER as late as 2 to 4 h following the endotoxin challenge. A greater degree of protection is observed inE. coli-challenged animals receiving ceftazidime than in those receiving imipenem, which is probably attributable to the higher levels of LPS released in vivo by the former antibiotic. Potent antiendotoxic activity, low toxicity, and ease of synthesis render the lipopolyamines candidate endotoxin-sequestering agents of potential significant therapeutic value.
A New Resistance Gene,
linB
, Conferring Resistance to Lincosamides by Nucleotidylation in
Enterococcus faecium
HM1025
Authors: Bozdogan Bülent , Berrezouga Latifa , Kuo Ming-Shang , Yurek David A. , Farley Kathleen A. , Stockman Brian J. , Leclercq Roland
Published: October 2018

Resistance to lincomycin and clindamycin in the clinical isolate
Enterococcus faecium
HM1025 is due to a ribosomal methylase encoded by an
ermAM
-like gene and the plasmid-mediated inactivation of these antibiotics. We have cloned and determined the nucleotide sequence of the gene responsible for the inactivation of lincosamides,
linB
. This gene encodes a 267-amino-acid lincosamide nucleotidyltransferase. The enzyme catalyzes 3-(5′-adenylation) (the adenylation of the hydroxyl group in position 3 of the molecules) of lincomycin and clindamycin. Expression of
linB
was observed in both
Escherichia coli
and
Staphylococcus aureus
. The deduced amino acid sequence of the enzyme did not display any significant homology with staphylococcal nucleotidyltransferases encoded by
linA
and
linA
′ genes. Sequences homologous to
linB
were found in 14 other clinical isolates of
E. faecium
, indicating the spread of the resistance trait in this species.
In Vivo and In Vitro Toxicodynamic Analyses of New Quinolone-and Nonsteroidal Anti-Inflammatory Drug-Induced Effects on the Central Nervous System
Authors: Kita Hideki , Matsuo Hirotami , Takanaga Hitomi , Kawakami Junichi , Yamamoto Koujirou , Iga Tatsuji , Naito Mikihiko , Tsuruo Takashi , Asanuma Atsushi , Yanagisawa Keiji , Sawada Yasufumi
Published: October 2018

We investigated the correlation between an in vivo isobologram based on the concentrations of new quinolones (NQs) in brain tissue and the administration of nonsteroidal anti-inflammatory drugs (NSAIDs) for the occurrence of convulsions in mice and an in vitro isobologram based on the concentrations of both drugs for changes in the γ-aminobutyric acid (GABA)-induced current response in
Xenopus
oocytes injected with mRNA from mouse brains in the presence of NQs and/or NSAIDs. After the administration of enoxacin (ENX) in the presence or absence of felbinac (FLB), ketoprofen (KTP), or flurbiprofen (FRP), a synergistic effect was observed in the isobologram based on the threshold concentration in brain tissue between mice with convulsions and those without convulsions. The three NSAIDs did not affect the pharmacokinetic behavior of ENX in the brain. However, the ENX-induced inhibition of the GABA response in the GABA
A
receptor expressed in
Xenopus
oocytes was enhanced in the presence of the three NSAIDs. The inhibition ratio profiles of the GABA responses for both drugs were analyzed with a newly developed toxicodynamic model. The inhibitory profiles for ENX in the presence of NSAIDs followed the order KTP (1.2 μM) > FRP (0.3 μM) > FLB (0.2 μM). These were 50- to 280-fold smaller than those observed in the absence of NSAIDs. The inhibition ratio (0.01 to 0.02) of the GABA
A
receptor in the presence of both drugs was well-fitted to the isobologram based on threshold concentrations of both drugs in brain tissue between mice with convulsions and those without convulsions, despite the presence of NSAIDs. In mice with convulsions, the inhibitory profiles of the threshold concentrations of both drugs in brain tissue of mice with convulsions and those without convulsions can be predicted quantitatively by using in vitro GABA response data and toxicodynamic model.
Integron- and Carbenicillinase-Mediated Reduced Susceptibility to Amoxicillin-Clavulanic Acid in Isolates of Multidrug-Resistant
Salmonella enterica
Serotype Typhimurium DT104 from French Patients
Authors: Poirel Laurent , Guibert Michele , Bellais Samuel , Naas Thierry , Nordmann Patrice
Published: October 2018

Fifty-seven
Salmonella enterica
serotype Typhimurium (
S. typhimurium
) isolates were collected from human patients in two French hospitals, Hôpital Antoine Béclère (Clamart, France) and Hôpital Bicêtre (Le Kremlin-Bicêtre, France), between 1996 and 1997. Thirty of them (52 percent) were resistant to amino-, carbeni-, and ureidopenicillins, had reduced susceptibility to amoxicillin-clavulanic acid, were susceptible to cephalothin, and were resistant to sulfonamides, streptomycin, chloramphenicol, and tetracyclines. All these strains possessed a
bla
PSE-1
-like gene and were of phage type DT104. Ten of them were studied in more detail, which revealed that
bla
PSE-1
is located on the variable region of a class 1 integron. This integron was found to be chromosomally located, as was another class 1 integron containing
aadA2
, a streptomycin-spectinomycin resistance gene. The reduced susceptibility to amoxicillin-clavulanic acid (and to ticarcillin-clavulanic acid) may result from the high level of hydrolysis of the β-lactam rather than to the clavulanic acid resistance properties of PSE-1 in these clonally related
S. typhimurium
isolates.
Carbapenem Resistance in
Escherichia coli
Associated with Plasmid-Determined CMY-4 β-Lactamase Production and Loss of an Outer Membrane Protein
Authors: Stapleton Paul D. , Shannon Kevin P. , French Gary L.
Published: October 2018

Three cefoxitin-resistant
Escherichia coli
isolates from stool specimens of a patient with leukemia were either resistant, intermediate, or sensitive to imipenem. Conjugation experiments showed that cefoxitin resistance, but not imipenem resistance, was transferable. All isolates were shown by isoelectric focusing to produce two β-lactamases with isoelectric points of 5.4 (TEM-1, confirmed by sequencing of a PCR product) and >8.5 (consistent with a class C β-lactamase). The gene coding for the unknown β-lactamase was cloned and sequenced and revealed an enzyme which had 99.9% sequence identity with the plasmid-determined class C β-lactamase CMY-2. The cloned β-lactamase gene differed from
bla
CMY-2
at one nucleotide position that resulted in an amino acid change, tryptophan to arginine at position 221. We propose that this enzyme be designated CMY-4. Both the imipenem-resistant and -intermediate isolates lacked a 38-kDa outer membrane protein (OMP) that was present in the imipenem-sensitive isolate. The lack of an OMP alone did not explain the difference in carbapenem susceptibilities observed. However, measurement of β-lactamase activities (including measurements under conditions where TEM-1 β-lactamase was inhibited) indicated that the imipenem-intermediate isolate expressed six- to eightfold less β-lactamase than did the other isolates. This study illustrates that carbapenem resistance in
E. coli
can arise from high-level expression of plasmid-mediated class C β-lactamase combined with an OMP deficiency. Furthermore, in the presence of an OMP deficiency, the level of expression of a plasmid-mediated class C β-lactamase is an important factor in determining whether
E. coli
isolates are fully resistant to carbapenems.
Pharmacokinetics of Ampicillin and Sulbactam in Pediatric Patients
Authors: Nahata Milap C. , Vashi Vijay I. , Swanson Robert N. , Messig Michael A. , Chung Menger
Published: October 2018

Intravenous ampicillin-sulbactam is effective in the treatment of various infections in adults, but little is known about the pharmacokinetics (PK) of ampicillin-sulbactam in children. The objective of this study was to determine the PK of ampicillin and sulbactam in pediatric patients with intra-abdominal infection, skin and/or skin structure infection, or periorbital-preseptal and facial cellulitis. Intravenous ampicillin and sulbactam (2:1), 40 to 80 mg/kg of body weight, were given every 6 h for 2 to 6 days to 28 pediatric patients. The ages ranged from 1 to 6 years for 10 patients, 6.1 to 10 years for 9 patients, and 10.1 to 12 years for 9 patients. Multiple blood samples were obtained and analyzed for ampicillin and sulbactam in plasma and serum by high-performance liquid chromatography. The mean maximum concentration of drug in serum ranged from 177 to 200 μg/ml for ampicillin and 82 to 102 μg/ml for sulbactam in the three age groups. The mean total clearance, steady-state distribution volume, and half-life were 4.76 ml/min/kg, 0.32 liter/kg, and 0.77 h, respectively, for ampicillin and 4.95 ml/min/kg, 0.34 liter/kg, and 0.81 h, respectively, for sulbactam. Dose or gender did not affect the PK of ampicillin or sulbactam. The PK of ampicillin and sulbactam in these patients were comparable to those reported in adults. The combination was well tolerated in pediatric patients.
Selective Effect of 2′,6′-Dihydroxy-4′-Methoxychalcone Isolated fromPiper aduncumonLeishmania amazonensis
Authors: Torres-Santos Eduardo Caio , Moreira Davyson Lima , Kaplan Maria Auxiliadora C. , Meirelles Maria Nazareth , Rossi-Bergmann Bartira
Published: October 2018

2′,6′-Dihydroxy-4′-methoxychalcone (DMC) was purified from the dichloromethane extract ofPiper aduncuminflorescences. DMC showed significant activity in vitro against promastigotes and intracellular amastigotes ofLeishmania amazonensis, with 50% effective doses of 0.5 and 24 μg/ml, respectively. Its inhibitory effect on amastigotes is apparently a direct effect on the parasites and is not due to activation of the nitrogen oxidative metabolism of macrophages, since the production of nitric oxide by both unstimulated and recombinant gamma interferon-stimulated macrophages was decreased rather than increased with DMC. The phagocytic activity of macrophages was functioning normally even with DMC concentrations as high as 80 μg/ml, as seen by electron microscopy and by the uptake of fluorescein isothiocyanate-labeled beads. Ultrastructural studies also showed that in the presence of DMC the mitochondria of promastigotes were enlarged and disorganized. Despite destruction of intracellular amastigotes, no disarrangement of macrophage organelles were observed, even at 80 μg of DMC/ml. These observations suggest that DMC is selectively toxic to the parasites. Its simple structure may well enable it to serve as a new lead compound for the synthesis of novel antileishmanial drugs.
In Vitro and In Vivo Experimental Activities of Antifungal Agents against
Fusarium solani
Authors: Guarro J. , Pujol I. , Mayayo E.
Published: October 2018

In the treatment of disseminated
Fusarium
infections, amphotericin B either alone or in combination with flucytosine and rifampin is the drug therapy most frequently used. The efficacy of these antifungal drugs was evaluated in a murine disseminated-infection model, with five strains of
Fusarium solani
. All the treatments were clearly ineffective.
Genetic Characterization of Resistance to Extended-Spectrum β-Lactams in
Klebsiella oxytoca
Isolates Recovered from Patients with Septicemia at Hospitals in the Stockholm Area
Authors: Wu Shang Wei , Dornbusch Kathrine , Kronvall Göran
Published: October 2018

Two β-lactamase gene regions were characterized by DNA sequencing in eight clinical isolates of
Klebsiella oxytoca
. The
bla
OXY-2a
region encoded a β-lactamase nearly identical to OXY-2 (one amino acid residue substituted) and conferred aztreonam and cefuroxime resistance on the
K. oxytoca
isolates. Overproduction of OXY-2a was caused by a G-to-A substitution of the fifth nucleotide in the −10 consensus sequence of
bla
OXY-2a
. The
bla
OXY-1a
was identified in a susceptible strain, and the OXY-1a enzyme differed from OXY-1 by two amino acid residues.
Characterization and Nucleotide Sequence of a
Klebsiella oxytoca
Cryptic Plasmid Encoding a CMY-Type β-Lactamase: Confirmation that the Plasmid-Mediated Cephamycinase Originated from the
Citrobacter freundii
AmpC β-Lactamase
Authors: Wu Shang Wei , Dornbusch Kathrine , Kronvall Göran , Norgren Mari
Published: October 2018

Plasmid pTKH11, originally obtained by electroporation of a
Klebsiella oxytoca
plasmid preparation into
Escherichia coli
XAC, expressed a high level of an AmpC-like β-lactamase. The enzyme, designated CMY-5, conferred resistance to extended-spectrum β-lactams in
E. coli
; nevertheless, the phenotype was cryptic in the
K. oxytoca
donor. Determination of the complete nucleotide sequence of pTKH11 revealed that the 8,193-bp plasmid encoded seven open reading frames, including that for the CMY-5 β-lactamase (
bla
CMY-5
). The
bla
CMY-5
product was similar to the plasmidic CMY-2 β-lactamase of
K. pneumoniae
and the chromosomal AmpC of
Citrobacter freundii
, with 99.7 and 97.0% identities, respectively; there was a substitution of phenylalanine in CMY-5 for isoleucine 105 in CMY-2.
bla
CMY-5
was followed by the
Blc
and
SugE
genes of
C. freundii
, and this cluster exhibited a genetic organization identical to that of the
ampC
region on the chromosome of
C. freundii
; these results confirmed that
C. freundii
AmpC was the evolutionary origin of the plasmidic cephamycinases. In the
K. oxytoca
host, the copy number of pTKH11 was very low and the plasmid coexisted with plasmid pNBL63. Analysis of the replication regions of the two plasmids revealed 97% sequence similarity in the RNA I transcripts; this result implied that the two plasmids might be incompatible. Incompatibility of the two plasmids might explain the cryptic phenotype of
bla
CMY-5
in
K. oxytoca
through an exclusion effect on pTKH11 by resident plasmid pNBL63.
Serine Protease Inhibitors Block Invasion of Host Cells by
Toxoplasma gondii
Authors: Conseil V. , Soête M. , Dubremetz J. F.
Published: October 2018

We investigated the effect of protease inhibitors on the asexual development of the protozoan parasite
Toxoplasma gondii
. Among the inhibitors tested only two irreversible serine protease inhibitors, 3,4-dichloroisocoumarin and 4-(2-aminoethyl)-benzenesulfonyl fluoride, clearly prevented invasion of the host cells by specifically affecting parasite targets in a dose-dependent manner, with 50% inhibitory concentrations between 1 and 5 and 50 and 100 μM, respectively. Neither compound significantly affected parasite morphology, basic metabolism, or gliding motility within the range of the experimental conditions in which inhibition of invasion was demonstrated. No partial invasion was observed, meaning that inhibition occurred at an early stage of the interaction. These results suggest that at least one serine protease of the parasite is involved in the invasive process of
T. gondii
.
Emergence of Antibiotic-Resistant
Pseudomonas aeruginosa
: Comparison of Risks Associated with Different Antipseudomonal Agents
Authors: Carmeli Yehuda , Troillet Nicolas , Eliopoulos George M. , Samore Matthew H.
Published: October 2018

Pseudomonas aeruginosa
is a leading cause of nosocomial infections. The risk of emergence of antibiotic resistance may vary with different antibiotic treatments. To compare the risks of emergence of resistance associated with four antipseudomonal agents, ciprofloxacin, ceftazidime, imipenem, and piperacillin, we conducted a cohort study, assessing relative risks for emergence of resistant
P. aeruginosa
in patients treated with any of these drugs. A total of 271 patients (followed for 3,810 days) with infections due to
P. aeruginosa
were treated with the study agents. Resistance emerged in 28 patients (10.2%). Adjusted hazard ratios for the emergence of resistance were as follows: ceftazidime, 0.7 (
P
= 0.4); ciprofloxacin, 0.8 (
P
= 0.6); imipenem, 2.8 (
P
= 0.02); and piperacillin, 1.7 (
P
= 0.3). Hazard ratios for emergence of resistance to each individual agent associated with treatment with the same agent were as follows: ceftazidime, 0.8 (
P
= 0.7); ciprofloxacin, 9.2 (
P
= 0.04); imipenem, 44 (
P
= 0.001); and piperacillin, 5.2 (
P
= 0.01). We concluded that there were evident differences among antibiotics in the likelihood that their use would allow emergence of resistance in
P. aeruginosa
. Ceftazidime was associated with the lowest risk, and imipenem had the highest risk.
Randomized, Placebo-Controlled, Double-Blind Trial To Evaluate the Efficacy of Mupirocin for Eradicating Carriage of Methicillin-Resistant
Staphylococcus aureus
Authors: Harbarth Stephan , Dharan Sasi , Liassine Nadia , Herrault Pascale , Auckenthaler Raymond , Pittet Didier
Published: October 2018

Mupirocin has been widely used for the clearance of nasal methicillin-resistant
Staphylococcus aureus
(MRSA) carriage during outbreaks, but no placebo-controlled trial has evaluated its value for eradicating MRSA carriage at multiple body sites in settings where MRSA is not epidemic. In a 1,500-bed teaching hospital with endemic MRSA, 102 patients colonized with MRSA were randomized into a double-blind, placebo-controlled trial and treated with either mupirocin (group M) or placebo (group P) applied to the anterior nares for 5 days; both groups used chlorhexidine soap for body washing. Follow-up screening, susceptibility testing, and genotyping were performed to evaluate treatment success, mupirocin or chlorhexidine resistance, and exogenous recolonization. At baseline, MRSA carriage was 60% in the nares, 38% in the groin, and 62% in other sites (skin lesions, urine). The MRSA eradication rate (all body sites) was 25% in group M (12 of 48 patients), compared to 18% in group P (9 of 50 patients; relative risk [RR], 0.72; 95% confidence interval [CI
95
], 0.33 to 1.55). At the end of follow-up, 44% of patients (19 of 43) were free of nasal MRSA in group M, compared to 23% (11 of 44) in group P (RR, 0.57; CI
95
, 0.31 to 1.04). Ten patients developed MRSA infections (three in group M and seven in group P). One mupirocin treatment failure was due to exogenous MRSA recolonization. No MRSA isolate showed chlorhexidine resistance or high-level mupirocin resistance; however, we observed an association (
P
= 0.003) between low-level mupirocin resistance at study entry (prevalence, 23%) and subsequent treatment failure in both study arms. These results suggest that nasal mupirocin is only marginally effective in the eradication of multisite MRSA carriage in a setting where MRSA is endemic.
Comparison of the Toxicity of Amphotericin B in 5% Dextrose with That of Amphotericin B in Fat Emulsion in a Randomized Trial with Cancer Patients
Authors: Nucci Marcio , Loureiro Monique , Silveira Fernanda , Casali Anna Raquel , Bouzas Luis Fernando , Velasco Eduardo , Spector Nelson , Pulcheri Wolmar
Published: October 2018

A multicentric randomized trial was undertaken to compare the toxicity of amphotericin B in 5% dextrose with that of amphotericin B in a fat emulsion (Intralipid) in cancer patients. Group 1 (
n
= 33) received amphotericin B diluted in 5% dextrose with premedication consisting of promethazine plus an antipyretic. Group 2 (
n
= 28) received amphotericin B diluted in 20% Intralipid without premedication. Amphotericin B was infused daily at a dose of 1 mg/kg of body weight over a 1-h period to members of both groups for empirical antifungal therapy (in neutropenic patients) or for the treatment of documented fungal infections. The majority of patients (80%) received empirical amphotericin B treatment. The two groups were comparable with regard to age, gender, underlying disease, and the following baseline characteristics: use of other nephrotoxic drugs and serum levels of potassium and creatinine. The median cumulative doses of amphotericin B were 240 mg in group 1 and 245 mg in group 2 (
P
= 0.73). Acute adverse events occurred in 88% of patients in group 1 and in 71% of those in group 2 (
P
= 0.11). Forty percent of the infusions in group 1 were associated with fever, compared to 23% in group 2 (
P
< 0.0001). In addition, patients in group 2 required less meperidine for the control of acute adverse events (
P
= 0.008), and fewer members of this group presented with hypokalemia (
P
= 0.004) or rigors (
P
< 0.0001). There was no difference in the proportions of patients with nephrotoxicity (
P
= 0.44). The success rates of empirical antifungal treatment were similar in the two groups (
P
= 0.9). Amphotericin B diluted in a lipid emulsion seems to be associated with a smaller number of acute adverse events and fewer cases of hypokalemia than amphotericin B diluted in 5% dextrose.
Molecular Characterization of Multidrug Resistance in
Streptococcus mitis
Authors: Poutanen Susan M. , de Azavedo Joyce , Willey Barbara M. , Low Donald E. , MacDonald Kelly S.
Published: October 2018

Antimicrobial resistance was characterized for 14 strains of
Streptococcus mitis
.
Hin
fI restriction fragment length mapping of
gyrA
PCR amplicons from three ciprofloxacin-resistant isolates correlated with mutations associated with such resistance in other organisms. By using PCR, seven erythromycin-resistant strains were found to possess either the
mef
or
ermB
gene. Hybridization revealed
tet
(M) in seven tetracycline-resistant isolates.
Biochemical-Genetic Analysis and Distribution of FAR-1, a Class A β-Lactamase from
Nocardia farcinica
Authors: Laurent Frederic , Poirel Laurent , Naas Thierry , Chaibi El Bachir , Labia Roger , Boiron Patrick , Nordmann Patrice
Published: October 2018

From genomic DNA of the clinical isolate
Nocardia farcinica
VIC, a 1.6-kb
Sau
3AI fragment was cloned and expressed in
Escherichia coli
JM109. The recombinant strain expressed a β-lactamase (pI, 4.6), FAR-1, which conferred high levels of resistance to amoxicillin, piperacillin, ticarcillin, and cephalothin. The hydrolysis constants (

k
cat

,

K
m

,

K
i

, and 50% inhibitory concentration) confirmed the MIC results and showed that FAR-1 activity is inhibited by clavulanic acid and at a low level by tazobactam and sulbactam. Moreover, FAR-1 β-lactamase hydrolyzes aztreonam (at a low level) without significant activity against ceftazidime, cefotaxime and imipenem. FAR-1 mature protein of molecular mass ca 32 kDa, has less than 60% amino acid identity with any other class A β-lactamases, being most closely related to PEN-A from
Burkholderia cepacia
(52%). A
bla
FAR-1
-like gene was found in all studied
N. farcinica
strains, underlining the constitutive origin of this gene.
In Vitro Antifungal Activity and Cytotoxicity of a Novel Membrane-Active Peptide
Authors: Hong Sung Yu , Oh Jong Eun , Lee Keun Hyeung
Published: October 2018

In the present study, we investigated the antifungal activity and cytotoxicity of a novel membrane-active peptide, KKVVFKVKFKK (MP). MP inhibited the growth of various pathogenic fungi isolated from patients and of fluconazole-resistant fungi at concentrations of 2 to 32 μg/ml. MP had potent fungicidal activity; the minimal fungicidal concentrations of the peptide were no more than fourfold greater than the MICs. Time course experiments of MP-induced killing of
Candida albicans
ATCC 36232 showed that the rate of killing was rapid and depended on the concentration of MP. MP had a strong synergism with other antifungal drugs; the fractional inhibitory concentration index values of MP with amphotericin B and fluconazole for
C. albicans
were 0.16 and 0.02, respectively. The 50% inhibitory concentrations of MP for NIH 3T3 and Jurkat cells were approximately 100 times higher than the MIC for
C. albicans
ATCC 36232, indicating that MP had high selectivity between the fungal and mammalian cells. These results suggest that MP has great advantages in the development of antifungal agents.
Efficacy of Gatifloxacin in Experimental
Escherichia coli
Meningitis
Authors: Lutsar Irja , Friedland Ian R. , Jafri Hasan S. , Wubbel Loretta , Ng Winston , Ghaffar Faryal , McCracken George H.
Published: October 2018

The effectiveness of gatifloxacin therapy (15 mg/kg every 5 h [q5h]) was compared with that of meropenem (75 mg/kg q5h) and cefotaxime (75 mg/kg q5h) therapy in experimental meningitis caused by a β-lactamase-producing strain of
Escherichia coli
. Gatifloxacin therapy was more rapidly bactericidal than cefotaxime but similar to meropenem therapy (bacterial killing rates at 5 h, 0.83 ± 0.26, 0.46 ± 0.3, and 0.73 ± 0.17 CFU/ml/h, respectively;
P
= 0.03 for gatifloxacin versus cefotaxime). At 10 h, seven of eight animals treated with gatifloxacin had <10 CFU/ml in their cerebrospinal fluid, compared with one of seven treated with cefotaxime therapy (
P
= 0.01). Gatifloxacin was at least as effective as currently available antibiotics in this model of
E. coli
meningitis.