bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vitro Evaluation of Drug Susceptibilities of
Babesia divergens
Isolates
Authors: Brasseur Philippe , Lecoublet Sophie , Kapel Nathalie , Favennec Loic , Ballet Jean J.
Published: October 2018

The susceptibilities of three bovine and two human
Babesia divergens
isolates to antimicrobial agents were evaluated in vitro by a tritiated hypoxanthine incorporation assay. The MICs at which 50% of isolates are inhibited (MIC
50
s) for mefloquine (chlorhydrate), chloroquine (sulfate), quinine (chlorhydrate), clindamycin (phosphate), pentamidine (isethionate), phenamidine (isethionate) plus oxomemazine (chlorhydrate), lincomycin (chlorhydrate monohydrate), and imidocarb (dipropionate) were determined. Except for imidocarb, the MIC
50
s observed for the different isolates were close. Imidocarb and the combination of phenamidine plus oxomemazine exhibited the highest in vitro activity, while antimalarial agents such as mefloquine, choroquine, and quinine were inactive. Other drugs had intermediate activities. The data support further in vitro evaluation of antimicrobial agents active against
B. divergens
for the improvement of therapeutic strategies.
Prophylaxis of Acute Osteomyelitis with Absorbable Ofloxacin-Impregnated Beads
Authors: Nicolau David P. , Nie Lin , Tessier Pamela R. , Kourea Helen P. , Nightingale Charles H.
Published: October 2018

We investigated the use of an ofloxacin-impregnated bioabsorbable composite for the prevention of acute
Staphylococcus aureus
osteomyelitis. New Zealand White rabbits were anesthetized, the femur was exposed, and a cortical hole was drilled. Animals were randomly given drug-free composites or ofloxacin-impregnated composites; the composites were placed at the site of injury, and the incision was closed. One hour later, all animals were intravenously inoculated with 5 × 10
4
CFU of
S. aureus
and observed for 28 days. Bone culture data revealed that
S. aureus
was isolated from 3 of 12 rabbits in the ofloxacin composite group and 9 of 11 animals in the control group (
P
= 0.02). Radiographic evaluation revealed that the drug-free group had a significantly (
P
= 0.01) greater degree of radiographic evidence of infection than the group given ofloxacin composites. Although a limited number of histologic samples were available, these data also paralleled the radiographic and culture data. This study demonstrates the effectiveness of the implantable ofloxacin bioabsorbable composites to prevent the development of acute osteomyelitis.
Activities and Time-Kill Studies of Selected Penicillins, β-Lactamase Inhibitor Combinations, and Glycopeptides against
Enterococcus faecalis
Authors: Hoellman Dianne B. , Visalli Melissa A. , Jacobs Michael R. , Appelbaum Peter C.
Published: October 2018

The activities of piperacillin, piperacillin-tazobactam, ticarcillin, ticarcillin-clavulanate, ampicillin, ampicillin-sulbactam, vancomycin, and teicoplanin were tested against 212
Enterococcus faecalis
strains (9 β-lactamase producers) by standard agar dilution MIC testing (10
4
CFU/spot). The MICs at which 50 and 90% of the isolates were inhibited (MIC
50
s and MIC
90
s, respectively) were as follows (μg/ml): piperacillin, 4 and 8; piperacillin-tazobactam, 4 and 8; ticarcillin, 64 and 128; ticarcillin-clavulanate, 64 and 128; ampicillin, 2 and 2; ampicillin-sulbactam, 1 and 2; vancomycin, 1 and 4; and teicoplanin, 0.5 and 1. Agar dilution MIC testing of the nine β-lactamase-positive strains with an inoculum of 10
6
CFU/spot revealed higher β-lactam MICs (piperacillin, 64 to >256 μg/ml; ticarcillin, 128 to >256 μg/ml; and ampicillin, 16 to 128 μg/ml); however, MICs with the addition of inhibitors were similar to those obtained with the lower inoculum. Time-kill studies of 15 strains showed that piperacillin-tazobactam was bactericidal (99.9% killing) for 14 strains after 24 h at four times the MIC, with 90% killing of all 15 strains at two times the MIC. After 12 and 6 h, 90% killing of 14 and 13 strains, respectively, was found at two times the MIC. Ampicillin gave 99.9% killing of 14 β-lactamase-negative strains after 24 h at eight times the MIC, with 90% killing of all 15 strains at two times the MIC. After 12 and 6 h, 90% killing of 14 and 13 strains, respectively, was found at two times the MIC. Killing by ticarcillin-clavulanate was slower than that observed for piperacillin-tazobactam, relative to the MIC. For the one β-lactamase-producing strain tested by time-kill analysis with a higher inoculum, addition of the three inhibitors (including sulbactam) to each of the β-lactams resulted in bactericidal activity at 24 h at two times the MIC. For an enzyme-negative strain, addition of inhibitors did not influence kinetics. Kinetics of vancomycin and teicoplanin were significantly slower than those of the β-lactams, with bactericidal activity against 6 strains after 24 h at eight times the MIC, with 90% killing of 12 and 14 strains, respectively, at four times the MIC. Slower-kill kinetics by both glycopeptides were observed at earlier periods.
Double-Blind Evaluation of the Safety and Pharmacokinetics of Multiple Oral Once-Daily 750-Milligram and 1-Gram Doses of Levofloxacin in Healthy Volunteers
Authors: Chien Shu-Chean , Wong Frank A. , Fowler Cynthia L. , Callery-D’Amico Susan V. , Williams R. Rex , Nayak Ramchandra , Chow Andrew T.
Published: October 2018

The safety and pharmacokinetics of once-daily oral levofloxacin in 16 healthy male volunteers were investigated in a randomized, double-blind, placebo-controlled study. Subjects were randomly assigned to the treatment (
n
= 10) or placebo group (
n
= 6). In study period 1, 750 mg of levofloxacin or a placebo was administered orally as a single dose on day 1, followed by a washout period on days 2 and 3; dosing resumed for days 4 to 10. Following a 3-day washout period, 1 g of levofloxacin or a placebo was administered in a similar fashion in period 2. Plasma and urine levofloxacin concentrations were measured by high-pressure liquid chromatography. Pharmacokinetic parameters were estimated by model-independent methods. Levofloxacin was rapidly absorbed after single and multiple once-daily 750-mg and 1-g doses with an apparently large volume of distribution. Peak plasma levofloxacin concentration (
C
max
) values were generally attained within 2 h postdose. The mean values of
C
max
and area under the concentration-time curve from 0 to 24 h (AUC
0–24
) following a single 750-mg dose were 7.1 μg/ml and 71.3 μg · h/ml, respectively, compared to 8.6 μg/ml and 90.7 μg · h/ml, respectively, at steady state. Following the single 1-g dose, mean
C
max
and AUC
0–24
values were 8.9 μg/ml and 95.4 μg · h/ml, respectively; corresponding values at steady state were 11.8 μg/ml and 118 μg · h/ml. These
C
max
and AUC
0–24
values indicate modest and similar degrees of accumulation upon multiple dosing at the two dose levels. Values of apparent total body clearance (CL/
F
), apparent volume of distribution (
V
ss
/
F
), half-life (
t
1/2
), and renal clearance (CL
R
) were similar for the two dose levels and did not vary from single to multiple dosing. Mean steady-state values for CL/
F
,
V
ss
/
F
,
t
1/2
, and CL
R
following 750 mg of levofloxacin were 143 ml/min, 100 liters, 8.8 h, and 116 ml/min, respectively; corresponding values for the 1-g dose were 146 ml/min, 105 liters, 8.9 h, and 105 ml/min. In general, the pharmacokinetics of levofloxacin in healthy subjects following 750-mg and 1-g single and multiple once-daily oral doses appear to be consistent with those found in previous studies of healthy volunteers given 500-mg doses. Levofloxacin was well tolerated at either high dose level. The most frequently reported drug-related adverse events were nausea and headache.
Dual Inhibition of Human Rhinovirus 2A and 3C Proteases by Homophthalimides
Authors: Wang Q. May , Johnson Robert B. , Jungheim Louis N. , Cohen Jeffrey D. , Villarreal Elcira C.
Published: October 2018

The 2A and 3C proteases encoded by human rhinoviruses (HRVs) are attractive targets for antiviral drug development due to their important roles in viral replication. Homophthalimides were originally identified as inhibitors of rhinovirus 3C protease through our screening effort. Previous studies have indicated that the antiviral activity of certain homophthalimides exceeded their in vitro inhibitory activity against the viral 3C protease, suggesting that an additional mechanism might be involved. Reported here is the identification of homophthalimides as potent inhibitors for another rhinovirus protease, designated 2A. Several homophthalimides exhibit time-dependent inhibition of the 2A protease in the low-micromolar range, and enzyme-inhibitor complexes were identified by mass spectrometry. Compound LY343814, one of the most potent inhibitors against HRV14 2A protease, had an antiviral 50% inhibitory concentration of 4.2 μM in the cell-based assay. Our data reveal that homophthalimides are not only 3C but also 2A protease inhibitors in vitro, implying that the antiviral activity associated with these compounds might result from inactivation of both 2A and 3C proteases in vivo. Since the processing of the viral polyprotein is hierarchical, dual inhibition of the two enzymes may result in cooperative inhibition of viral replication. On the basis of the current understanding of their enzyme inhibitory mechanism, homophthalimides, as a group of novel nonpeptidic antirhinovirus agents, merit further structure-action relationship studies.
Efficacy of Sulfamethoxypyridazine in a Murine Model of
Pneumocystis carinii
Pneumonia
Authors: Bartlett Marilyn S. , Shaw Margaret M. , Smith James W. , Meshnick Steven R.
Published: October 2018

Sulfamethoxazole is the component of co-trimoxazole responsible for its efficacy against
Pneumocystis carinii
pneumonia, but this drug is associated with frequent adverse effects. Sulfamethoxypyridazine is significantly more effective than sulfamethoxazole against a murine model of
P. carinii
and might be a candidate for testing in infected patients.
Mutations in
aarE
, the
ubiA
Homolog of
Providencia stuartii
, Result in High-Level Aminoglycoside Resistance and Reduced Expression of the Chromosomal Aminoglycoside 2′-
N
-Acetyltransferase
Authors: Paradise Michael R. , Cook Gregory , Poole Robert K. , Rather Philip N.
Published: October 2018

The
aarE1
allele was identified on the basis of the resulting phenotype of increased aminoglycoside resistance. The
aarE1
mutation also resulted in a small-colony phenotype and decreased levels of
aac(2′)-Ia
mRNA. The deduced AarE gene product displayed 61% amino acid identity to the
Escherichia coli
UbiA protein, an octaprenyltransferase required for the second step of ubiquinone biosynthesis. Complementation experiments in both
Providencia stuartii
and
E. coli
demonstrated that
aarE
and
ubiA
are functionally equivalent.
In Vitro Susceptibilities of
Bordetella pertussis
and
Bordetella parapertussis
to Two Ketolides (HMR 3004 and HMR 3647), Four Macrolides (Azithromycin, Clarithromycin, Erythromycin A, and Roxithromycin), and Two Ansamycins (Rifampin and Rifapentine)
Authors: Hoppe Jörg E. , Bryskier André
Published: October 2018

When tested by agar dilution on Mueller-Hinton agar supplemented with 5% horse blood, the ketolides HMR 3004 and HMR 3647 were slightly more active (MIC at which 90% of the isolates were inhibited [MIC
90
], 0.03 μg/ml) against
Bordetella pertussis
than azithromycin, clarithromycin, erythromycin A, and roxithromycin. Azithromycin (MIC
90
, 0.06 μg/ml) was the most active compound against
B. parapertussis
. Rifampin and rifapentine were considerably less active.
Human Cytomegalovirus Mutant with Sequence-Dependent Resistance to the Phosphorothioate Oligonucleotide Fomivirsen (ISIS 2922)
Authors: Mulamba Gilbert B. , Hu André , Azad Raana F. , Anderson Kevin P. , Coen Donald M.
Published: October 2018

A human cytomegalovirus mutant that was isolated for resistance (10-fold) to the antisense oligonucleotide fomivirsen (ISIS 2922) exhibited cross-resistance to a modified derivative of fomivirsen with an identical base sequence but little or no resistance to an oligonucleotide with an unrelated sequence. No changes in the mutant’s DNA corresponding to the fomivirsen target sequence were found.
Field Evaluation of the Prophylactic Effect of an Isometamidium Sustained-Release Device against Trypanosomiasis in Cattle
Authors: Diarra B. , Diall O. , Geerts S. , Kageruka P. , Lemmouchi Y. , Schacht E. , Eisler M. C. , Holmes P.
Published: October 2018

In order to compare the prophylactic effect provided by a poly(d,l-lactide) sustained-release device (SRD) containing isometamidium (ISMM) with that provided by the classical intramuscular injection of the drug, a field trial was carried out at the Madina Diassa Ranch in Mali. One- to 3-year-old N’Dama cattle were randomly divided into three groups. The first group (n= 42) was treated with ISMM at a dose of 1 mg/kg of body weight, the second group (n= 44) received the same dose of the drug via an SRD, which was subcutaneously implanted in the shoulder region, and the third group (n= 36) was kept as an untreated control group. All animals were treated with diminazene aceturate (7 mg/kg of body weight) 2 weeks before the start of the experiment and were tested monthly by the buffy coat technique for a period of 8 months.Glossina morsitans submorsitanswas the most important tsetse species, with apparent densities (number of catches/trap/day) varying between 11.9 and 38.7 over the experimental period. Eight months after treatment the cumulative infection rates were 27.7, 58.5, and 77.4% in the group with the SRD implant, the group receiving the intramuscular injection, and the control group, respectively. Statistical analysis showed that the incidence of trypanosomiasis was significantly lower (P= 0.006) in the group which received ISMM via the SRD than in the one which was treated with ISMM intramuscularly.
Biological Characterization of Endotoxins Released from Antibiotic-TreatedPseudomonas aeruginosaandEscherichia coli
Authors: Kirikae Teruo , Kirikae Fumiko , Saito Shinji , Tominaga Kaoru , Tamura Hirohi , Uemura Yayoi , Yokochi Takashi , Nakano Masayasu
Published: October 2018

The supernatants taken fromPseudomonas aeruginosaandEscherichia colicultures in human sera or chemically defined M9 medium in the presence of ceftazidime (CAZ) contained high levels of endotoxin, while those taken from the same cultures in the presence of imipenem (IPM) yielded a very low level of endotoxin. The biological activities of endotoxin in the supernatants were compared with those of phenol water-extracted lipopolysaccharide (LPS). The endotoxin released from the organisms as a result of CAZ treatment (CAZ-released endotoxin) contained a large amount of protein. The protein, however, lacked endotoxic activity, since the endotoxin did not show any in vivo toxic effects in LPS-hyporesponsive C3H/HeJ mice sensitized withd-(+)-galactosamine (GalN) or any activation of C3H/HeJ mouse macrophages in vitro. The activities of CAZ- and IPM-released endotoxin (as assessed by a chromogenicLimulustest) were fundamentally the same as those ofP. aeruginosaLPS, since their regression lines were parallel. The CAZ-released endotoxin was similar to purified LPS with respect to the following biological activities in LPS-responsive C3H/HeN mice and LPS-hyporesponsive C3H/HeJ mice: lethal toxicity in GalN-sensitized mice, in vitro induction of tumor necrosis factor- and NO production by macrophages, and mitogen-activated protein kinase activation in macrophages. The macrophage activation by CAZ-released endotoxin as well as LPS was mainly dependent on the presence of serum factor and CD14 antigen. Polymyxin B blocked the activity. These findings indicate that the endotoxic activity of CAZ-released endotoxin is due primarily to LPS (lipid A).
Modulation of Gyrase-Mediated DNA Cleavage and Cell Killing by ATP
Authors: Li Tsai-Kun , Liu Leroy F.
Published: October 2018

An uncoupler of oxidative phosphorylation, 2,4-dinitrophenol, and an aconitase inhibitor, fluoroacetic acid, both of which are known to lower the cellular ATP pool, protected
Escherichia coli
cells from the bactericidal actions of gyrase poisons including quinolone antibiotics, nalidixic acid and ciprofloxacin, and the epipodophyllotoxins VP-16 and VM-26. Using purified
E. coli
DNA gyrase, we examined the effect of ATP on gyrase-mediated DNA cleavage in the presence of these gyrase poisons. ATP was shown to stimulate gyrase-mediated DNA cleavage from 10- to more than 100-fold in the presence of these gyrase poisons. ADP antagonized the stimulatory effect of ATP. Consequently, gyrase-mediated DNA cleavage induced by gyrase poisons is modulated by the ATP concentration/ADP concentration ([ATP]/[ADP]) ratio. Coumermycin A1, an inhibitor of the ATPase subunit of DNA gyrase, like ADP, also effectively antagonized the stimulatory effect of ATP on gyrase-mediated DNA cleavage induced by gyrase poisons. Furthermore, coumermycin A1, like DNP and fluoroacetic acid, also protected cells from the bactericidal action of gyrase poisons. In the aggregate, our results are consistent with the notion that the [ATP]/[ADP] ratio, through its modulatory effect on the gyrase-mediated DNA cleavage, is an important determinant of cellular susceptibility to gyrase poisons.
In Vitro Activities of Benzimidazoles against
Echinococcus multilocularis
Metacestodes
Authors: Jura Heike , Bader Augustinus , Frosch Matthias
Published: October 2018

Alveolar echinococcosis, caused by the larval (metacestode) stage of the tapeworm
Echinococcus multilocularis
, is a lethal parasitosis of the liver prevalent in the Northern Hemisphere. For chemotherapy the benzimidazole derivatives mebendazole and albendazole were introduced, and their use has resulted in a significant improvement in the survival rates. However, data from experiments with animals and clinical observations indicate that these drugs elicit only parasitostatic activity and in most cases are not able to completely eliminate the parasitic metacestode tissue. In the present study, we applied a culture system for the in vitro growth and proliferation of
E. multilocularis
metacestodes to analyze the parasitostatic and parasitocidal potential of mebendazole. Here, we demonstrate for the first time that at concentrations of >0.1 μM, i.e., at concentrations used for therapy of human alveolar echinococcosis, this antihelminth drug is parasitocidal in vitro. Viability assessment was performed by infection experiments with
Meriones unguiculatus
and mebendazole-treated metacestode tissue and by reverse transcription-PCR for the detection of
E. multilocularis
mRNA. The
E. multilocularis
in vitro model proved to be a valuable tool for the analysis of the potential of antihelminth drugs.
Chromosomally Encoded AmpC-Type β-Lactamase in a Clinical Isolate of
Proteus mirabilis
Authors: Bret L. , Chanal-Claris C. , Sirot D. , Chaibi E. B. , Labia R. , Sirot J.
Published: October 2018

A clinical strain of
Proteus mirabilis
(CF09) isolated from urine specimens of a patient displayed resistance to amoxicillin (MIC >4,096 μg/ml), ticarcillin (4,096 μg/ml), cefoxitin (64 μg/ml), cefotaxime (256 μg/ml), and ceftazidime (128 μg/ml) and required an elevated MIC of aztreonam (4 μg/ml). Clavulanic acid did not act synergistically with cephalosporins. Two β-lactamases with apparent pIs of 5.6 and 9.0 were identified by isoelectric focusing on a gel. Substrate and inhibition profiles were characteristic of an AmpC-type β-lactamase with a pI of 9.0. Amplification by PCR with primers for
ampC
genes (
Escherichia coli
,
Enterobacter cloacae
, and
Citrobacter freundii
) of a 756-bp DNA fragment from strain CF09 was obtained only with
C. freundii
-specific primers. Hybridization results showed that the
ampC
gene is only chromosomally located while the
TEM
gene is plasmid located. After cloning of the gene, analysis of the complete nucleotide sequence (1,146 bp) showed that this
ampC
gene is close to
bla
CMY-2
, from which it differs by three point mutations leading to amino acid substitutions Glu → Gly at position 22, Trp → Arg at position 201, and Ser → Asn at position 343. AmpC β-lactamases derived from that of
C. freundii
(LAT-1, LAT-2, BIL-1, and CMY-2) have been found in
Klebsiella pneumoniae
,
E. coli
, and
Enterobacter aerogenes
and have been reported to be plasmid borne. This is the first example of a chromosomally encoded AmpC-type β-lactamase observed in
P. mirabilis
. We suggest that it be designated CMY-3.
Interactions of β-Lactamases with Sanfetrinem (GV 104326) Compared to Those with Imipenem and with Oral β-Lactams
Authors: Babini Gioia S. , Yuan Meifang , Livermore David M.
Published: October 2018

Sanfetrinem is a trinem β-lactam which can be administered orally as a hexatil ester. We examined whether its β-lactamase interactions resembled those of the available carbapenems, i.e., stable to AmpC and extended-spectrum β-lactamases but labile to class B and functional group 2f enzymes. The comparator drugs were imipenem, oral cephalosporins, and amoxicillin. MICs were determined for β-lactamase expression variants, and hydrolysis was examined directly with representative enzymes. Sanfetrinem was a weak inducer of AmpC β-lactamases below the MIC and had slight lability, with a
k
cat
of 0.00033 s
−1
for the
Enterobacter cloacae
enzyme. Its MICs for AmpC-derepressed
E. cloacae
and
Citrobacter freundii
were 4 to 8 μg/ml, compared with MICs of 0.12 to 2 μg/ml for AmpC-inducible and -basal strains; MICs for AmpC-derepressed
Serratia marcescens
and
Morganella morganii
were not raised. Cefixime and cefpodoxime were more labile than sanfetrinem to the
E. cloacae
AmpC enzyme, and AmpC-derepressed mutants showed much greater resistance; imipenem was more stable and retained full activity against derepressed mutants. Like imipenem, sanfetrinem was stable to TEM-1 and TEM-10 enzymes and retained full activity against isolates and transconjugants with various extended-spectrum TEM and SHV enzymes, whereas these organisms were resistant to cefixime and cefpodoxime. Sanfetrinem, like imipenem and cefixime but unlike cefpodoxime, also retained activity against
Proteus vulgaris
and
Klebsiella oxytoca
strains that hyperproduced potent chromosomal class A β-lactamases. Functional group 2f enzymes, including Sme-1, NMC-A, and an unnamed enzyme from
Acinetobacter
spp., increased the sanfetrinem MICs by up to 64-fold. These enzymes also compromised the activities of imipenem and amoxicillin but not those of the cephalosporins. The hydrolysis of sanfetrinem was examined with a purified Sme-1 enzyme, and biphasic kinetics were found. Finally, zinc β-lactamases, including IMP-1 and the L1 enzyme of
Stenotrophomonas maltophilia
, conferred resistance to sanfetrinem and all other β-lactams tested, and hydrolysis was confirmed with the IMP-1 enzyme. We conclude that sanfetrinem has β-lactamase interactions similar to those of the available carbapenems except that it is a weaker inducer of AmpC types, with some tendency to select derepressed mutants, unlike imipenem and meropenem.
Influence of Test Conditions on Antifungal Time-Kill Curve Results: Proposal for Standardized Methods
Authors: Klepser Michael E. , Ernst Erika J. , Lewis Russell E. , Ernst Michael E. , Pfaller Michael A.
Published: October 2018

This study was designed to examine the effects of antifungal carryover, agitation, and starting inoculum on the results of time-kill tests conducted with various
Candida
species. Two isolates each of
Candida albicans
,
Candida tropicalis
, and
Candida glabrata
were utilized. Test antifungal agents included fluconazole, amphotericin B, and LY303366. Time-kill tests were conducted in RPMI 1640 medium buffered with morpholinepropanesulfonic acid (MOPS) to a pH of 7.0 and incubated at 35°C. Prior to testing, the existence of antifungal carryover was evaluated at antifungal concentrations ranging from 1× to 16× MIC by four plating methods: direct plating of 10, 30, and 100 μl of test suspension and filtration of 30 μl of test suspension through a 0.45-μm-pore-size filter. Time-kill curves were performed with each isolate at drug concentrations equal to 2× MIC, using a starting inoculum of approximately 10
5
CFU/ml, and incubated with or without agitation. Last, inoculum experiments were conducted over three ranges of starting inocula: 5 × 10
2
to 1 × 10
4
, >1 × 10
4
to 1 × 10
6
, and >1 × 10
6
to 1 × 10
8
CFU/ml. Significant antifungal carryover (>25% reduction in CFU/milliliter from the control value) was observed with amphotericin B and fluconazole; however, carryover was eliminated with filtration. Agitation did not appreciably affect results. The starting inoculum did not significantly affect the activity of fluconazole or amphotericin B; however, the activity of LY303366 may be influenced by the starting inoculum. Before antifungal time-kill curve methods are routinely employed by investigators, methodology should be scrutinized and standardized procedures should be developed.
Pharmacokinetics of a New Carbapenem, DA-1131, after Intravenous Administration to Rats with Uranyl Nitrate-Induced Acute Renal Failure
Authors: Kim So H. , Shim Hyun J. , Kim Won B. , Lee Myung G.
Published: October 2018

Because the physiological changes that occur in patients with acute renal failure could alter the pharmacokinetics of the drugs used to treat the disease, the pharmacokinetics of DA-1131, a new carbapenem antibiotic, were investigated after 1-min intravenous administration of the drug (50 mg/kg of body weight) to control rats and rats with uranyl nitrate-induced acute renal failure (U-ARF rats). The impaired kidney function was observed in U-ARF rats on the basis of physiological parameters observed by microscopy of the kidney and obtained by chemical analysis of the plasma. After a 1-min intravenous infusion of DA-1131, the concentrations in plasma and the total area under the plasma concentration-time curve from time zero to time infinity increased significantly in U-ARF rats compared with those in control rats (13,000 versus 4,400 μg · min/ml). This was due to the significantly slower total body clearance (CL) of DA-1131 (3.84 versus 11.4 ml/min/kg) from U-ARF rats than from control rats. The significantly slower CL of DA-1131 from U-ARF rats was due to both significantly slower renal clearance (0.000635 versus 4.95 ml/min/kg because of a significant decrease in the 8-h urinary excretion of unchanged DA-1131 [1.54 versus 43.8% of the intravenous dose] due to impaired kidney function, as proved by the significant decrease in creatinine clearance [0.0159 versus 4.29 ml/min/kg]) and significantly slower nonrenal clearance (3.80 versus 6.34 ml/min/kg because of a significant decrease in the metabolism of DA-1131 in the kidney) in U-ARF rats. The amounts of DA-1131 recovered from all tissues studied (except the kidneys) were significantly higher for U-ARF rats than for control rats; however, the ratios of the amount in tissue to the concentration in plasma (except those for the kidney, small intestine, and spleen) were not significantly different between the two groups of rats, indicating that the affinity of DA-1131 for rat tissues was not changed considerably in U-ARF rats.
Alterations in PBP 1A Essential for High-Level Penicillin Resistance in
Streptococcus pneumoniae
Authors: Smith Anthony M. , Klugman Keith P.
Published: October 2018

High-level penicillin resistance in pneumococci is due to alterations in penicillin-binding proteins (PBPs) 2X, 2B, and 1A. We have sequenced the penicillin-binding domain of PBP 1A from penicillin-resistant South African pneumococcal isolates and have identified amino acid substitutions which are common to all the resistant isolates analyzed. Site-directed mutagenesis was then used to determine whether particular amino acid substitutions at specific positions in PBP 1A mediate penicillin resistance. PCR was used to isolate PBP 2X, 2B, and 1A genes from clinical isolate 8303 (penicillin MIC, 4 μg/ml). These wild-type PBP genes were cloned into pGEM-3Zf and were used as the transforming DNA. Susceptible strain R6 (MIC, 0.015 μg/ml) was first transformed with PBP 2X and 2B DNA, resulting in PBP 2X/2B-R6 transformants for which MICs were 0.25 μg/ml. When further transformed with PBP 1A DNA, 2X/2B/1A-R6 transformants for which MICs were 1.5 μg/ml were obtained. Site-directed mutagenesis of the PBP 1A gene from isolate 8303 was then used to reverse particular amino acid substitutions, followed by transformation of PBP 2X/2B-R6 transformants with the mutagenized PBP 1A DNA. For PBP 2X/2B/1A-R6 transformants, the introduction of the reversal of Thr-371 by Ser or Ala in PBP 1A decreased the MIC from 1.5 to 0.5 μg/ml, whereas the reversal of four consecutive amino acid substitutions (Thr-574 by Asn, Ser-575 by Thr, Gln-576 by Gly, and Phe-577 by Tyr) decreased the MIC from 1.5 to 0.375 μg/ml. These data reveal that amino acid residue 371 and residues 574 to 577 of PBP 1A are important positions in PBP 1A with respect to the interaction with penicillin and the development of resistance.
Randomized Trial of Trimethoprim-Sulfamethoxazole versus Pyrimethamine-Sulfadiazine for Therapy of Toxoplasmic Encephalitis in Patients with AIDS
Authors: Torre Donato , Casari Salvatore , Speranza Filippo , Donisi Alessandra , Gregis Giampietro , Poggio Antonio , Ranieri Sergio , Orani Anna , Angarano Gioacchino , Chiodo Francesco , Fiori GianPaolo , Carosi Giampiero ,   the Italian Collaborative Study Group
Published: October 2018

The aim of the present pilot study was to compare the efficacy and safety of trimethoprim (TMP) and sulfamethoxazole (SMX) with those of the standard therapy pyrimethamine (P)-sulfadiazine (S) for the treatment of toxoplasmic encephalitis in patients with AIDS. This was a pilot, multicenter, randomized, and prospective study. Patients were randomly assigned to receive TMP (10 mg/kg of body weight/day) and SMX (50 mg/kg/day) or P (50 mg daily) and S (60 mg/kg/day) as acute therapy (for 4 weeks) and then as maintenance therapy for 3 months at half of the original dosage. Seventy-seven patients were enrolled and randomized to the study: 40 patients were treated with TMP-SMX and 37 were treated with P-S. There was no statistically significant difference in clinical efficacy during acute therapy. In contrast, patients randomized to TMP-SMX appeared more likely to achieve a complete radiologic response after acute therapy. Adverse reactions were significantly more frequent in patients treated with P-S, and skin rash was the most common adverse event noted in these patients. In conclusion, the results of the study suggest that TMP-SMX appears to be a valuable alternative to P-S, in particular in patients with opportunistic bacterial infections.
Changes in MIC Alter Responses of
Pseudomonas aeruginosa
to Tobramycin Exposure
Authors: Ioannides-Demos L. L. , Liolios L. , Wood P. , Spicer W. J. , McLean A. J.
Published: October 2018

The pharmacokinetic parameters determining antibiotic efficacy are peak concentrations (
C
max
), minimum (trough) concentrations (
C
min
), and area under the concentration-time curve (AUC). There is general agreement about the importance of
C
max
and AUC for aminoglycosides, but this is not so for maintenance of
C
min
. With in vitro exposures modelling in vivo administration,
Pseudomonas aeruginosa
reference strain ATCC 27853 (MIC, 1 mg/liter) and a higher-MIC (relatively resistant) clinical isolate (MIC, 4 mg/liter) were used to explore bacteriostatic and bactericidal outcomes. With
P. aeruginosa
ATCC 27853, kill followed a complete bolus profile with a 30-min postdistribution peak (
C
peak30
) of 10 mg/liter. The clinical isolate required a
C
peak30
bolus profile of 20 mg/liter for kill, and there was no difference between the efficacies of the bolus and infusion exposures. Bolus profiles that were truncated at 8.5 h and producing sublethal effects were then combined with a wide range of
C
min
s. With a
C
peak30
profile of 8 mg/liter,
P. aeruginosa
ATCC 27853 showed a graded bacteriostatic response until a
C
min
of ≥0.8 mg/liter, when complete kill resulted. In contrast, bactericidal effects on the clinical isolate required a
C
peak30
profile of 18 mg/liter with a
C
min
of ≥1.0 mg/liter. Therefore,
C
min
also contributes to the bactericidal effect of tobramycin, with requirements showing minor variation with change in MIC. Dosing principles for relatively resistant (higher-MIC) organisms are suggested from the data. Relatively higher aminoglycoside doses via infusion regimens are likely to be needed to generate higher peak concentrations and higher AUC values necessary for bactericidal effect in resistant organisms. Maintenance of trough concentrations on the order of 1.0 mg/liter during the interdose interval will tend to guard against the possibility of inadequate peak and AUC exposures for kill.
Comparison of In Vitro Antifungal Activities of Free and Liposome-Encapsulated Nystatin with Those of Four Amphotericin B Formulations
Authors: Johnson Elizabeth M. , Ojwang Joshua O. , Szekely Adrien , Wallace Thomas L. , Warnock David W.
Published: October 2018

The in vitro activity of a multilamellar liposomal formulation of nystatin (Nyotran) was compared with those of free nystatin and four pharmaceutical preparations of amphotericin B. MICs for 200 isolates of two
Aspergillus
spp., seven
Candida
spp., and
Cryptococcus neoformans
were determined by a broth microdilution adaptation of the method recommended by the National Committee for Clinical Laboratory Standards. Minimum lethal concentrations (MLCs) of the six antifungal preparations were also determined. Both nystatin formulations possessed fungistatic and fungicidal activities against the 10 species tested. Liposomal nystatin appeared to be as active as free nystatin, with MICs and MLCs that were similar to, or lower than, those of the latter. Neither formulation of nystatin was as active as amphotericin B deoxycholate (Fungizone) or amphotericin B lipid complex (Abelcet), but both were more effective than liposomal amphotericin B (AmBisome). Our results suggest that further evaluation of liposomal nystatin is justified.
Antifungal Activity of 3′-Deoxyadenosine (Cordycepin)
Authors: Sugar Alan M. , McCaffrey Ronald P.
Published: October 2018

The antifungal activity of the nucleoside analog 3′-deoxyadenosine (cordycepin) was studied in a murine model of invasive candidiasis. When protected from deamination by either deoxycoformycin or coformycin, both of which are adenosine deaminase inhibitors, cordycepin exhibited potent antifungal efficacy, as demonstrated by prolongation of survival and a decrease in CFU in the kidneys of mice treated with cordycepin plus an adenosine deaminase inhibitor. The antifungal effect was seen with three different
Candida
isolates:
Candida albicans
64, a relatively fluconazole-resistant clinical isolate of
C. albicans
(MIC, 16 μg/ml), and the fluconazole-resistant
Candida krusei
. Cordycepin and related compounds may provide another avenue for the discovery of clinically useful antifungal drugs.
Characterization of a Murine Monoclonal Antibody toCryptococcus neoformansPolysaccharide That Is a Candidate for Human Therapeutic Studies
Authors: Casadevall Arturo , Cleare Wendy , Feldmesser Marta , Glatman-Freedman Aharona , Goldman David L. , Kozel Thomas R. , Lendvai Nikoletta , Mukherjee Jean , Pirofski Liise-anne , Rivera Johanna , Rosas Angel L. , Scharff Matthew D. , Valadon Philippe , Westin Katherine , Zhong Zhaojing
Published: October 2018

The murine monoclonal antibody (MAb) 18B7 [immunoglobulin G1(κ)] is in preclinical development for treatment ofCryptococcus neoformansinfections. In anticipation of its use in humans, we defined the serological and biological properties of MAb 18B7 in detail. Structural comparison to the related protective MAb 2H1 revealed conservation of the antigen binding site despite several amino acid differences. MAb 18B7 was shown by immunofluorescence and agglutination studies to bind to all four serotypes ofC. neoformans, opsonizeC. neoformansserotypes A and D, enhance human and mouse effector cell antifungal activity, and activate the complement pathway leading to deposition of complement component 3 (C3) on the cryptococcal capsule. Administration of MAb 18B7 to mice led to rapid clearance of serum cryptococcal antigen and deposition in the liver and spleen. Immunohistochemical studies revealed that MAb 18B7 bound to capsular glucuronoxylomannan in infected mouse tissues. No reactivity of MAb 18B7 with normal human, rat, or mouse tissues was detected. The results show that both the variable and constant regions of MAb 18B7 are biologically functional and support the use of this MAb in human therapeutic trials.
Ceftazidime and Aztreonam Resistance in
Providencia stuartii
: Characterization of a Natural TEM-Derived ExtendedSpectrum β-Lactamase, TEM-60
Authors: Franceschini Nicola , Perilli Mariagrazia , Segatore Bernardetta , Setacci Domenico , Amicosante Gianfranco , Mazzariol Annarita , Cornaglia Giuseppe
Published: October 2018

A plasmid-encoded β-lactamase produced from a clinical strain of
Providencia stuartii
has been purified and characterized. The gene coding for the β-lactamase was cloned and sequenced. It appears to be a new natural TEM-derived enzyme, named TEM-60. Point mutations (Q39K, L51P, E104K, and R164S) are present with respect to the TEM-1 enzyme; the mutation L51P has never been previously reported, with the exception of the chromosomally encoded extended-spectrum β-lactamase PER-1. Kinetic parameters relative to penicillins, cephalosporins, and monobactams other than mechanism-based inactivators were related to the in vitro susceptibility phenotype.
In Vitro Activities of the New Ketolide Antibiotics HMR 3004 and HMR 3647 against
Streptococcus pneumoniae
in Germany
Authors: Reinert Ralf René , Bryskier André , Lütticken Rudolf
Published: October 2018

The comparative in vitro activity of HMR 3004 and HMR 3647, new ketolide antibiotics, was tested by a standard agar dilution technique against 221 pneumococcal strains, including isolates with intermediate levels of resistance to penicillin and erythromycin-resistant isolates. The ketolides were more active than other macrolides and showed excellent activity against erythromycin-resistant strains. All the strains were inhibited by ≤2 μg of HMR 3004/ml or by ≤0.5 μg of HMR 3647/ml.
Famciclovir and Valaciclovir Differ in the Prevention of Herpes Simplex Virus Type 1 Latency in Mice: a Quantitative Study
Authors: Thackray Alana M. , Field Hugh J.
Published: October 2018

Famciclovir (FCV) and valaciclovir (VACV) have previously been shown to be potent inhibitors of herpes simplex virus type 1 (HSV-1) in a murine cutaneous model. In the present study, mice were inoculated in the skin of the left ear pinna with herpes simplex virus (HSV) type 1. Antiviral therapy was started on different days postinoculation (p.i.), terminating at the end of day 10 p.i. The compounds were administered twice daily by oral gavage at 50 mg/kg of body weight/dose. Mice were sampled on day 5 p.i., during the acute phase of the infection, and the titers of infectious virus in the target tissues (ear, brain stem, and trigeminal ganglia) were determined. At 2 to 3 months p.i., the ipsilateral and contralateral trigeminal and cervical dorsal root ganglia were explanted, and four different methods were used to detect latent HSV. The methods were (i) conventional explant culture for 5 days followed by homogenization, (ii) long-term culture (up to 73 days) of whole ganglia, followed by homogenization, (iii) dissociation by enzymatic disaggregation and an infectious center assay, and (iv) in situ hybridization to detect latency-associated transcripts (LATs). The conventional explant culture method was the least sensitive method, while in situ staining for LAT was the most sensitive, and all mice, including those treated from early times with FCV, were shown to be latently infected. Significantly less latent virus was detected by all four methods, however, in ganglia obtained from mice that had been treated with FCV in comparison with the amount detected in ganglia from mice that had been treated with VACV. However, in no case was latency completely eliminated.
Antifungal Susceptibilities ofPaecilomycesSpecies
Authors: Aguilar C. , Pujol I. , Sala J. , Guarro J.
Published: October 2018

The MICs and minimum fungicidal concentrations (MFCs) of amphotericin B, miconazole, itraconazole, ketoconazole, fluconazole, and flucytosine for 52 isolates ofPaecilomycesspecies were evaluated by the broth microdilution method, largely based on the recommendations of the National Committee for Clinical Laboratory Standards (document M27-A). The fungal isolates tested included 16P. variotii, 11P. lilacinus, 9P. marquandii, 6P. fumosoroseus, 4P. javanicus, and 2P. viridisisolates and 1 isolate of each of the following species:P. carneus,P. farinosus,P. fulvus, andP. niveus. The MFCs and the MICs at which 90% of isolates were inhibited (MIC90s) for the six antifungal agents were remarkably high; the MIC50s indicated that amphotericin B, miconazole, itraconazole, and ketoconazole had good activities, while fluconazole and flucytosine demonstrated poor efficacy. The ranges of the MICs were generally wider and lower than those of the MFCs. There were significant susceptibility differences among the species. All species with the exception ofP. variotiiwere highly resistant to fluconazole and flucytosine;P. variotiiwas susceptible to flucytosine. Amphotericin B and the rest of the azoles showed good activity againstP. variotii, while all the antifungal agents assayed showed low efficacy againstP. lilacinus.
In Vitro and In Vivo Activities of Levofloxacin against Biofilm-Producing
Pseudomonas aeruginosa
Authors: Ishida Hiroko , Ishida Yoshihisa , Kurosaka Yuichi , Otani Tsuyoshi , Sato Kenichi , Kobayashi Hiroyuki
Published: October 2018

Interactions between biofilm cells of
Pseudomonas aeruginosa
and levofloxacin were studied.
P. aeruginosa
incubated for 6 days with Teflon sheets formed a biofilm on its surface. Against the biofilm bacteria, levofloxacin at an MIC determined by the standard method for the strain was highly bactericidal whereas gentamicin, ceftazidime, and ciprofloxacin showed no significant killing activity. Levofloxacin, ciprofloxacin, and gentamicin, but not ceftazidime, exhibited killing activity against nongrowing cells of the strain incubated in phosphate buffer. In addition, levofloxacin, ciprofloxacin, and ceftazidime, but not gentamicin, showed the ability to penetrate an agar containing alginate. These findings may explain the efficacy of levofloxacin and the ineffectiveness of gentamicin and ceftazidime against biofilm bacteria; however, the cause of the ineffectiveness of ciprofloxacin still remains to be determined. In experimental pneumonia in guinea pigs, in which the biofilm mode of growth of the strain was observed in the lung, only levofloxacin exhibited substantial therapeutic efficacy. These findings suggest the significant role of levofloxacin in therapy of biofilm bacterium-associated infectious diseases.
Differences in the Lipoprotein Distribution of Free and Liposome-Associated All-
trans
-Retinoic Acid in Human, Dog, and Rat Plasma Are Due to Variations in Lipoprotein Lipid and Protein Content
Authors: Wasan Kishor M. , Ramaswamy Manisha , Ng Samson P. , Wong Wesley , Parrott Steven C. , Ojwang Joshua O. , Wallace Thomas , Cossum Paul A.
Published: October 2018

The objective of the proposed study was to determine the distribution in plasma lipoprotein of free all-
trans
retinoic acid (ATRA) and liposomal ATRA (Atragen; composed of dimyristoyl phosphatidylcholine and soybean oil) following incubation in human, rat, and dog plasma. When ATRA and Atragen at concentrations of 1, 5, 10, and 25 μg/ml were incubated in human and rat plasma for 5, 60, and 180 min, the majority of the tretinoin was recovered in the lipoprotein-deficient plasma fraction. However, when ATRA and Atragen were incubated in dog plasma, the majority of the tretinoin (>40%) was recovered in the high-density lipoprotein (HDL) fraction. No differences in the plasma distribution between ATRA and Atragen were found. These data suggest that a significant percentage of tretinoin associates with plasma lipoproteins (primarily the HDL fraction) upon incubation in human, dog, and rat plasma. Differences between the lipoprotein lipid and protein profiles in human plasma and in dog and rat plasma influenced the plasma distribution of ATRA and Atragen. Differences in lipoprotein distribution between ATRA and Atragen were not observed, suggesting that the drug’s distribution in plasma is not influenced by its incorporation into these liposomes.
Ceftazidime-Resistant
Klebsiella pneumoniae
and
Escherichia coli
Isolates Producing TEM-10 and TEM-43 β-Lactamases from St. Louis, Missouri
Authors: Yang Youjun , Bhachech Niraja , Bradford Patricia A. , Jett Bradley D. , Sahm Daniel F. , Bush Karen
Published: October 2018

Ceftazidime-resistant
Escherichia coli
and
Klebsiella pneumoniae
(49 and 102 isolates, respectively) were collected from Barnes-Jewish Hospital, St. Louis, Mo., from 1992 to 1996. They were uniformly resistant to ceftazidime, generally resistant to aztreonam, and variably susceptible to cefotaxime. Four representative
E. coli
strains and 15
Klebsiella
strains were examined. From one to four β-lactamases were produced per strain, with three possible enzymes related to ceftazidime resistance: enzymes with pI values of 5.6, 6.1, or 7.6. By pulsed-field gel electrophoresis there were at least 13 different
Klebsiella
strain types and 3 different
E. coli
strain types, indicating that the outbreak was not clonal. After cloning and sequencing of the β-lactamase-encoding genes, the enzyme with a pI of 5.6 was identified as TEM-10. The enzyme with a pI of 6.1 was a novel TEM variant (TEM-43) with Lys at 104, His at 164, and Thr at 182. TEM-43 showed broad-spectrum hydrolytic activity against all penicillins, with the highest hydrolysis rate for ceftazidime compared to those for the other expanded-spectrum cephalosporins. Aztreonam was also a good substrate for TEM-43, with hydrolytic activity similar to that of ceftazidime and affinity higher than that of ceftazidime. The TEM-43 β-lactamase was well inhibited by clavulanic acid and tazobactam at concentrations of <10 nM. Sulbactam was less effective than the other inhibitors. The Thr182 mutation previously reported in an inhibitor-resistant β-lactamase did not cause the TEM-43 enzyme to become resistant to any of the inhibitors.