bluuebunny/crossref_metadata_2025 huggingface dataset:
Double-blind, comparative study of rufloxacin once daily versus amoxicillin three times a day in treatment of outpatients with exacerbations of chronic bronchitis
Authors: Klietmann W , Cesana M , Rondel R K , Focht J
Published: June 2012

In a double-blind, randomized, multicenter study, the efficacy and safety of two dosage schedules of rufloxacin once daily were compared with those of amoxicillin three times a day in the treatment of 192 outpatients with exacerbations of chronic bronchitis. Rufloxacin was given as a single oral dose of 400 mg on day 1 and single daily doses of 200 mg on the subsequent 9 days (n = 64) or as 300 mg on day 1 and then 150 mg daily for 9 days (n = 63); amoxicillin was given as 500 mg orally three times a day for 10 days (n = 65). Clinical and bacteriological assessments were carried out before treatment, between study days 3 and 5, and at days 1 and 8 after treatment. Pretreatment cultures were positive for 139 patients, the most frequently isolated pathogens being Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae. Clinical success rates were comparable in the three groups (94, 95, and 98%, respectively), as were bacteriological success rates at the end of treatment (93, 95, and 91%, respectively) and at follow-up (88, 95, and 98%, respectively). The power to detect a significant 15% difference in cure rates was 74.9%. Follow-up bacteriological failures from pneumococcal infection were 18% in both rufloxacin groups combined and 5% in the amoxicillin group. The 200-mg dose regimen achieved average steady-state concentrations in plasma higher than did the 150-mg dose regimen (3.75 versus 2.72 micrograms/ml). Adverse events occurred in 11 and 13 patients, respectively, on rufloxacin and 8 on amoxicillin. This study shows that rufloxacin once daily ay be a possible option for the treatment of acute exacerbations of chronic bronchitis. The 200-mg daily oral dose preceeded by a loading dose of 400 mg displays a better pharmacokinetic profile than the lower dose.
Mycobacterium avium strains resistant to clarithromycin and azithromycin
Authors: Heifets L , Mor N , Vanderkolk J
Published: June 2012

Mycobacterium avium strains susceptible to clarithromycin and azithromycin contain mutants resistant to these macrolides with a frequency of 1.1 x 10(-10) to 1.2 x 10(-6). Cross-resistance between clarithromycin and azithromycin was demonstrated with mutants selected in the laboratory as well as with resistant strains isolated from patients. The susceptibility-resistance patterns of the macrolide-resistant strains with drugs other than macrolides were the same as those of the original susceptible strains. The emergence of clarithromycin resistance in patients was a result of multiplication of the preexisting resistant mutants that survived the elimination of bacteria during the initial period of treatment and was an exclusive cause of the relapse of bacteremia.
Response to antifungal therapy by human immunodeficiency virus-infected patients with disseminated Penicillium marneffei infections and in vitro susceptibilities of isolates from clinical specimens
Authors: Supparatpinyo K , Nelson K E , Merz W G , Breslin B J , Cooper C R , Kamwan C , Sirisanthana T
Published: June 2012

Eighty-six patients with laboratory evidence of human immunodeficiency virus infection presented to Chiang Mai University Hospital in Chiang Mai, Thailand, between 1 June 1990 and 30 June 1992 with systemic infection caused by the dimorphic fungus Penicillium marneffei. Thirty isolates of P. marneffei from clinical specimens from these patients were tested for their in vitro susceptibilities to amphotericin B, 5-fluorocytosine, miconazole, ketoconazole, itraconazole, and fluconazole. P. marneffei was highly susceptible to miconazole, itraconazole, ketoconazole, and 5-fluorocytosine. Amphotericin B showed intermediate antifungal activity, while fluconazole was the least active; some strains of the fungus were resistant to fluconazole. The clinical and microbiological responses correlated with the overall patterns of in vitro susceptibility to the azoles, whereas results with amphotericin B were more difficult to assess. Antibiotic failures of initial therapy occurred in 8 of 35 (22.8%) patients treated with amphotericin B, 3 of 12 (25%) patients treated with itraconazole, and 7 of 11 (63.6%) patients treated with fluconazole. Itraconazole or ketoconazole should be considered to be the drug of first choice in the treatment of mild to moderately severe P. marneffei infection. Parenteral therapy with amphotericin B may be required for seriously ill patients. Since at least 12 patients who responded to initial therapy relapsed within 6 months regardless of initial antifungal therapy, maintenance oral therapy with itraconazole or ketoconazole may be necessary.
High-level penicillin resistance and penicillin-gentamicin synergy in Enterococcus faecium
Authors: Torres C , Tenorio C , Lantero M , Gastañares M J , Baquero F
Published: June 2012

Thirty-seven Enterococcus faecium strains with different levels of penicillin susceptibility were studied in time-kill experiments with a fixed concentration (5 micrograms/ml) of gentamicin combined with different penicillin concentrations (6 to 600 micrograms/ml). Synergy was defined as a relative decrease in counts of greater than 2 log10 CFU per milliliter after 24 h of incubation when the combination of the antibiotics was compared with its most active component alone. The minimal synergistic penicillin concentrations found were 6 micrograms/ml for 16 of 16 strains for which penicillin MICs were < or = 25 micrograms/ml, 20 to 100 micrograms/ml for 14 of 17 strains for which penicillin MICs were 50 to 200 micrograms/ml, and 200 to 500 micrograms/ml for 4 of 4 strains for which MICs penicillin were > 200 micrograms/ml. Penicillin-gentamicin synergy was observed even in high-level penicillin-resistant E. faecium strains at penicillin concentrations close to one-half the penicillin MIC. The possibility of treating infections caused by high-level penicillin-resistant E. faecium strains with penicillin-gentamicin combinations in particular cases may depend on the penicillin levels attainable in vivo.
In vitro antibiotic susceptibility testing of different strains of Mycoplasma fermentans isolated from a variety of sources
Authors: Hayes M M , Foo H H , Kotani H , Wear D J , Lo S C
Published: June 2012

The in vitro susceptibilities to antibiotics of 24 strains of Mycoplasma fermentans (isolated from human immunodeficiency virus type 1-infected AIDS patients, non-AIDS patients with acute respiratory disease, and tissue culture) were determined. MICs for 90% of the strains tested (micrograms per milliliter) were obtained for chloramphenicol (1.25), ciprofloxacin (0.078), clindamycin (0.078), doxycycline (0.625), erythromycin (> 10), gentamicin (> 10), levofloxacin (0.078), lincomycin (0.156), streptomycin (> 10), and tetracycline (0.625).
Inhibition of visna virus replication by 2',3'-dideoxynucleosides and acyclic nucleoside phosphonate analogs
Authors: Thormar H , Balzarini J , Holy A , Jindrich J , Rosenberg I , Debyser Z , Desmyter J , De Clercq E
Published: June 2012

A series of acyclic nucleoside phosphonate (ANP) and 2',3'-dideoxynucleoside (ddN) derivatives were evaluated for their inhibitory effects on visna virus replication and maedi/visna virus-induced syncytium formation in sheep choroid plexus cells. Most ANP derivatives inhibited virus replication and syncytium formation within a concentration range of 0.2 to 1.8 microM. Among the most active ANP derivatives ranked (R)-9-(2-phosphonomethoxypropyl)adenine, (R)-9-(2-phosphonomethoxypropyl)-2,6-diaminopurine, and (S)-9-(3-fluoro-2-phosphonomethoxypropyl)adenine. Of the ddN derivatives, 2',3'-dideoxycytidine (ddCyd) proved to be the most inhibitory to visna virus-induced syncytium formation (50% effective concentration, 0.02 microM). The purine ddN analogs (i.e., 2',3'-dideoxyinosine, 2',3'-dideoxyadenosine, 2',3'-dideoxyguanosine, and 2,6-diaminopurine-2',3'-dideoxyribosine) were 10- to 30-fold less effective, and the thymidine derivatives 2',3'-didehydro-2',3'-dideoxythymidine (D4T) and 3'-azido-2',3'-dideoxythymidine (AZT) were more than 500-fold less inhibitory to visna virus than ddCyd. The 5'-triphosphate forms of AZT and D4T were 100- to 600-fold more inhibitory to visna virus particle-derived reverse transcriptase than was the 5'-triphosphate of ddCyd. The apparent discrepancy between the inhibitory effects of these ddN derivatives on virus replication and viral reverse transcriptase activity most likely reflects differences in the metabolic conversion of ddCyd versus D4T and AZT in sheep choroid plexus cells.
In vitro antibacterial activities of PD 138312 and PD 140248, new fluoronaphthyridines with outstanding gram-positive potency
Authors: Huband M D , Cohen M A , Meservey M A , Roland G E , Yoder S L , Dazer M E , Domagala J M
Published: June 2012

PD 138312 and PD 140248 are new quinolones with high in vitro activities against a wide spectrum of bacterial species, notably including gram-positive isolates. The respective MICs (in micrograms per milliliter) of PD 138312 and PD 140248 capable of inhibiting > or = 90% of the strains were < or = 0.06 and < or = 0.06 for oxacillin-susceptible and -resistant staphylococci, streptococci (including Streptococcus pyogenes, S. agalactiae, S. pneumoniae, and viridans group streptococci), Haemophilus influenzae, Moraxella catarrhalis, and Neisseria gonorrhoeae; 0.125 and 0.03 for Legionella pneumophila; 0.25 and 0.125 for Listeria monocytogenes; 0.25 and 0.25 for Enterococcus faecalis; 0.5 and 0.06 for anaerobic gram-positive cocci; 0.5 and 0.25 for Acinetobacter spp.; 0.5 and 0.5 for members of the family Enterobacteriaceae (excluding Serratia marcescens); 2 and 0.5 for Bacteroides fragilis; 2 and 2 for Serratia marcescens and ciprofloxacin-resistant staphylococci; and 8 and 4 for Pseudomonas aeruginosa.
Effect of clindamycin on intracellular replication, protein synthesis, and infectivity of Toxoplasma gondii
Authors: Blais J , Tardif C , Chamberland S
Published: June 2012

We studied the effects of clindamycin and a combination of clindamycin and pyrimethamine on the proliferation of Toxoplasma gondii in cultured mammalian cells and the effect of clindamycin on the parasite's RNA and protein syntheses. Infected macrophages were treated for 48 h with clindamycin or a combination of clindamycin and pyrimethamine, and the 50% inhibitory concentrations for parasite growth were 32.50 +/- 1.30 and 10.78 +/- 0.56 micrograms/ml, respectively. A modified susceptibility assay was also used to measure the effect of low concentrations of clindamycin on T. gondii. Macrophages and bovine turbinate cells were infected with low numbers of tachyzoites and were exposed to low concentrations of clindamycin for 5 days. In these systems, a concentration of 10 ng of clindamycin per ml inhibited 50% of the growth of the parasite in macrophages, while it completely prohibited the growth of the parasite in epithelial cells. When free tachyzoites were preexposed to clindamycin for 4 h, the reduction of parasite infectivity was proportional to the amount of drug; 100 ng of clindamycin per ml reduced the infectivity of T. gondii to 46.5% +/- 8.5% of that of the untreated control. A concentration of 40 micrograms of clindamycin per ml reduced protein synthesis by 56.2% +/- 6.0% but had no effect on RNA synthesis after a 4-h exposure of free tachyzoites of T. gondii to the drug. Our results show that long-term exposure to low concentrations of clindamycin reduces the level of replication of T. gondii, that clindamycin affects the protein synthesis of free parasites, and that clindamycin impairs the ability of tachyzoites to infect host cells.
Proteolytic enzymes: a new treatment strategy for prosthetic infections?
Authors: Selan L , Berlutti F , Passariello C , Comodi-Ballanti M R , Thaller M C
Published: June 2012

Among the different mechanisms of bacterial resistance to antimicrobial agents that have been studied, biofilm formation is one of the most widespread. This mechanism is frequently the cause of failure in the treatment of prosthetic device infections, and several attempts have been made to develop molecules and protocols that are able to inhibit biofilm-embedded bacteria. We present data suggesting the possibility that proteolytic enzymes could significantly enhance the activities of antibiotics against biofilms. Antibiotic susceptibility tests on both planktonic and sessile cultures, studies on the dynamics of colonization of 10 biofilm-forming isolates, and then bioluminescence and scanning electron microscopy under seven different experimental conditions showed that serratiopeptidase greatly enhances the activity of ofloxacin on sessile cultures and can inhibit biofilm formation.
Morphological response of Bilophila wadsworthia to imipenem: correlation with properties of penicillin-binding proteins
Authors: Summanen P , Wexler H M , Lee K , Becker S A , Garcia M M , Finegold S M
Published: June 2012

The penicillin-binding protein (PBP) patterns of six strains of Bilophila wadsworthia were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and subsequent fluorography of membrane preparations labelled with [3H]benzylpenicillin. The PBP profiles among the strains were similar; generally, seven to nine PBP-reactive bands could be visualized; their molecular weights ranged from 31 to 137 kDa. The relative affinities of the PBPs of four strains of B. wadsworthia for imipenem were examined and correlated with the morphological responses of the cells to imipenem. Morphological changes were examined by light and electron microscopies. Light microscopy revealed that at low concentrations (less than the MIC), imipenem induced the formation of rounded and bulging cells; rarely, elongation without filamentation was observed. In the presence of imipenem at the MIC, spheroplast formation was observed. Scanning and transmission electron microscopies revealed round forms together with larger, multilobate cells in the presence of subinhibitory concentrations of imipenem, suggesting that new growth sites were initiated while cell division was inhibited. Peeling of the outer membrane was also seen. Spheroplasts were very large (up to 30 microns in diameter) and stable in aqueous solution. Inhibition of the PBPs could be seen in the presence of low imipenem concentrations.
Correlation of tobramycin-induced inhibition of protein synthesis with postantibiotic effect in Escherichia coli
Authors: Barmada S , Kohlhepp S , Leggett J , Dworkin R , Gilbert D
Published: June 2012

Scant data exist on intracellular events during aminoglycoside-induced postantibiotic effect (PAE). We examined DNA, RNA, and protein syntheses after tobramycin exposure using [3H]thymidine, [14C]uracil, and [14C]alanine incorporation in a clinical Escherichia coli strain. Late-log-phase bacteria in oxygenated minimal salts medium at 37 degrees C were exposed to tobramycin (7.5 micrograms/ml) (twice the MIC) for 30 min. Tobramycin caused a kill of 2 log10 CFU/ml prior to drug removal by filtration and a 5-h PAE, measured by viable counts. Excess amounts of labelled precursors were added to tobramycin-exposed organisms during, immediately after, and at various intervals following exposure. In the presence of tobramycin, DNA, RNA, and protein syntheses were sequentially inhibited within 1 generation time. Following drug removal, both DNA and RNA syntheses promptly resumed, suggesting readily dissociable nonspecific binding to DNA and RNA. However, total protein synthesis did not resume until 4 h later. beta-Galactosidase activity, a measure of functional enzymatic protein synthesis, was also inhibited for 4 h after drug removal. Bacterium length, measured by confocal microscopy, increased during PAE. Two distinct populations eventually emerged: one that returned to control dimensions and one that remained excessively elongated by the end of PAE (2.5 microns versus 4.0 microns; P < 0.05). We hypothesize that only viable cells return to the control morphology. Flow cytometry showed enhanced DNA complexity during PAE, consistent with either impaired cellular protein synthesis in viable cells or perturbations in dying cells. In summary, duration of PAE correlated with inhibition of total and functional protein synthesis but not DNA or RNA synthesis.
Expression of the tetK gene from Staphylococcus aureus in Escherichia coli: comparison of substrate specificities of TetA(B), TetA(C), and TetK efflux proteins
Authors: Guay G G , Rothstein D M
Published: June 2012

The tetK gene, which encodes a tetracycline efflux pump from Staphylococcus aureus, was expressed in Escherichia coli by using an inducible, low-level expression system. The tetK gene, as well as the tetA(B) gene from the transposon Tn10 and the tetA(C) gene from plasmid pBR322, was subjected to the regulatory control of the lac repressor, and resistance to tetracycline was measured as a function of the isopropyl-beta-D-thiogalactopyranoside concentration. The maximum resistance of the E. coli strain containing the tetK construct was comparable to the maximum resistance of the strain containing the tetA(C) construct but was less than the resistance of the strain containing the tetA(B) construct. Overexpression of the tetK, tetA(B), or tetA(C) genes was toxic. When expression was regulated so that resistance to tetracycline was comparable, then the TetA(B) and TetA(C) proteins conferred very similar levels of resistance to a variety of tetracycline derivatives. In contrast, the TetK protein was less capable of conferring resistance to the tetracycline derivatives minocycline, 6-deoxy-6-demethyltetracycline, and doxycycline. The implications for the recognition of various tetracycline substituents by the TetK protein are discussed.
Efficacy of oral WIN 54954 for prophylaxis of experimental rhinovirus infection
Authors: Turner R B , Dutko F J , Goldstein N H , Lockwood G , Hayden F G
Published: June 2012

The efficacy of oral WIN 54954 for the prevention of rhinovirus infection and illness was tested in two randomized, double-blinded, placebo-controlled volunteer challenge studies. Volunteers were inoculated with rhinovirus type 39 (MIC of WIN 54954, 0.17 microgram/ml) or rhinovirus type 23 (MIC, 0.016 microgram/ml). The volunteers received two doses of drug (600 mg per dose) or placebo on the first day; this was followed by three doses on each of the subsequent 5 days. All volunteers were challenged with virus after the third dose of study drug. No significant antiviral or clinical effect was detected in either study. Pharmacokinetic studies revealed that on the last day of drug administration, 38 of 39 (97%) volunteers had trough levels of WIN 54954 in plasma greater than the MIC for the respective virus. Nasal wash specimens collected on the same day revealed a detectable level in only 6 of 24 (25%) volunteers at the peak (range, 6 to 24 ng/ml) and in only 2 of 14 (14%) volunteers at the trough (range, 6 and 7 ng/ml). These results suggest that the lack of efficacy of WIN 54954 against rhinovirus may be related to an inability to deliver sufficient drug to the site of viral infection.
In vitro and in vivo antibacterial activities of FK037, a novel parenteral broad-spectrum cephalosporin
Authors: Fu K P , Foleno B D , Lafredo S C , LoCoco J M , Isaacson D M
Published: June 2012

FK037, a new parenteral cephalosporin, is an oxime-type cephem antibiotic with a 1-hydroxyethyl-5-amino-pyrazole moiety at the 3 position. FK037 was evaluated for antimicrobial activity in vitro and in vivo. In vitro, FK037 was twofold or more active than ceftazidime, cefoperazone, cefotaxime, and ceftriaxone against Pseudomonas aeruginosa (MIC for 90% of the strains [MIC90] = 32 micrograms/ml), members of the family Enterobacteriaceae (MIC90 < or = 2 micrograms/ml), group A streptococci (MIC90 = 0.015 microgram/ml), and methicillin-sensitive or -resistant coagulase-negative staphylococci (MIC90 = 2 and 16 micrograms/ml, respectively). In addition, the activity of FK037 was equal to or greater than that of ceftazidime, cefotaxime, or ceftriaxone against Streptococcus pneumoniae (MIC90 = 0.12 microgram/ml) and methicillin-sensitive or -resistant Staphylococcus aureus (MIC90 = 2 and 16 micrograms/ml, respectively). FK037 was more active in vitro than cefepime (two- to fourfold) and cefpirome (twofold) against S. aureus. In murine systemic infection models, FK037 showed potent activity against P. aeruginosa, Escherichia coli, and methicillin-sensitive and methicillin-resistant S. aureus. FK037 was also efficacious in a mouse model of pyelonephritis caused by S. aureus or Klebsiella pneumoniae and in a mouse model of pneumococcal pneumonia caused by S. pneumoniae. Additional studies on this compound to assess its potential clinical utility are warranted.
Activity of the carbapenem panipenem and role of the OprD (D2) protein in its diffusion through the Pseudomonas aeruginosa outer membrane
Authors: Fukuoka T , Ohya S , Narita T , Katsuta M , Iijima M , Masuda N , Yasuda H , Trias J , Nikaido H
Published: June 2012

Evidence of permeation of panipenem through the OprD (D2) channel of Pseudomonas aeruginosa outer membrane was shown by using OprD protein-producing and -nonproducing strains which contained plasmid pHN4, which codes for L-1 beta-lactamase of Xanthomonas maltophilia. Permeation by panipenem was determined by measuring hydrolysis of the carbapenem by beta-lactamase in the periplasmic space. Permeation by panipenem was also determined by counting uptake of [14C]panipenem into P. aeruginosa PAO1 and its OprD protein-deficient mutant, and this permeation of PAO1 was inhibited by L-lysine. These results indicate that panipenem, as well as imipenem, uses the OprD channel, which functions as a specific channel for diffusion of basic amino acids. Panipenem and imipenem showed stronger activities against PAO1 and clinical isolates in human serum than in Mueller-Hinton broth, which contains more amino acids than human serum does. The activities of the carbapenems were reduced by addition of L-lysine to human serum. Similar results were obtained with mouse serum and ascitic fluid. In contrast, such a change in the activities of carbapenems was not observed with an OprD protein-deficient mutant, suggesting that the main reason for the strong activities of carbapenems in biological fluids is a decrease in competition between the antibiotics and basic amino acids for permeation through the OprD channel. Panipenem and imipenem showed much stronger therapeutic efficacies against experimental infections with P. aeruginosa in mice than did the reference antibiotics. Their in vivo activities were more consistent with their MICs in biological fluids than with those in Mueller-Hinton broth.
Abnormal Peptidoglycan Produced in a Methicillin-Resistant Strain of
Staphylococcus aureus
Grown in the Presence of Methicillin: Functional Role for Penicillin-Binding Protein 2A in Cell Wall Synthesis
Authors: de Jonge Boudewijn L. M. , Tomasz Alexander
Published: June 2012

Upon the addition of methicillin even at relatively low concentrations (5 μg/ml or 0.3% of the MIC) to the medium, methicillin-resistant staphylococci shift to the production of a new peptidoglycan with an abnormal muropeptide composition which may be the synthetic product of penicillin-binding protein 2A.
Comparison of the effects of 3'-azidothymidine with those of neutralizing antibodies on simian immunodeficiency virus infection in macrophages
Authors: McEntee M F , Flexner C , Farzadegan H , Pitha P , Narayan O
Published: June 2012

We previously showed that simian immunodeficiency virus-infected macaque macrophages contacting uninfected CD4+ lymphocytes caused extensive cell fusion and synthesis of phlogistic cytokines. In this study, macaque macrophage cultures inoculated with SIVmac251 and treated simultaneously with 10 microM 3'-azidothymidine (AZT) became infected and produced small amounts of viral antigen (p27) but failed to fuse with CD4+ CEM174 cells. When AZT was added 1 to 3 days after virus inoculation, the infected cells caused fusion and the release of tumor necrosis factor and produced increasing amounts of p27. In contrast, neutralizing antibodies prevented infection when added at the time of virus inoculation, and they were much more effective than AZT in limiting virus replication, fusion cytopathic effect, and cytokine production when added up to 3 days postinoculation. Neutralizing antibodies may be more effective than AZT in reducing the virus load in the macrophage population and in preventing both cell fusion and the production of potentially pathogenic cytokines.
Structure-activity relationships and modes of action of 9-anilinoacridines against chloroquine-resistant Plasmodium falciparum in vitro
Authors: Chavalitshewinkoon P , Wilairat P , Gamage S , Denny W , Figgitt D , Ralph R
Published: June 2012

An in vitro investigation of the structure-activity profiles for a range of 9-anilinoacridines on drug-resistant Plasmodium falciparum is reported. C-3, 6-diamino substitution, low lipophilicity, and high pKa values substantially increased the activities of the 9-anilinoacridines tested. There appeared to be no correlation between DNA binding and antimalarial activity. 3,6-Diamino-1'-amino-9-anilinoacridine (compound 13) was the most active compound tested; it had a 50% inhibitory concentration of 25 nM. In vitro mammalian cell growth assays showed compound 13 to be one of the least cytotoxic 9-anilinoacridines (50% inhibitory concentration, 15 microM). Both compound 13 and the antimalarial drug pyronaridine inhibited the decatenation activity of P. falciparum DNA topoisomerase II at concentrations of 10 and 11 microM, respectively.
Biologic effects after a single dose of poly(I):poly(C12U) in healthy volunteers
Authors: Hendrix C W , Margolick J B , Petty B G , Markham R B , Nerhood L , Farzadegan H , Ts'o P O , Lietman P S
Published: June 2012

Poly(I):poly(C12U) (mismatched double-stranded RNA; atvogen), an interferon inducer, is active against human immunodeficiency virus in vitro. To determine the extent and duration of the biologic effects of poly(I):poly(C12U), we administered a single dose of the drug to healthy volunteers in a randomized, double-blind, placebo-controlled 2-week crossover study. We analyzed blood for alpha and gamma interferons, neopterin, 2',5'-oligoadenylate synthetase, lymphocyte surface markers, lymphocyte proliferation after exposure to soluble antigens and mitogens, and natural killer cell activity. Minimal biologic effects were observed after administration of a single 200-mg dose to four volunteers; therefore, the dose was increased to 600 mg in 10 subjects. Only neopterin levels and symptoms were greater after administration of 600 mg of poly(I):poly(C12U) than after administration of placebo (Wilcoxon signed rank sum test, P = 0.06). A definite response in 2',5'-oligoadenylate synthetase activity, however, was seen in a few subjects. Neither alpha nor gamma interferon was detectable in serum after poly(I):poly(C12U) dosing. The neopterin changes after administration of poly(I):poly(C12U) were similar at both poly(I):poly(C12U) dose levels, with an early decrease at 6 h, a peak at 1 day, and a gradual decrease toward the baseline over the following 3 days. A mild flu-like syndrome occurred in one-half of the subjects following administration of poly(I):poly(C12U) and in only one subject following administration of placebo. This syndrome resolved within 16 h after poly(I):poly(C12U) dosing. We conclude that poly(I):poly(C12U) does not induce measurable levels of interferon and causes only minimal biologic or toxic effects among those parameters measured after administration of a single dose in the 200- to 600-mg dose range in health volunteers.
High-capacity in vitro assessment of anti-hepatitis B virus compound selectivity by a virion-specific polymerase chain reaction assay
Authors: Jansen R W , Johnson L C , Averett D R
Published: June 2012

An integrated assessment system specific for hepatitis B virus (HBV) Dane particle DNA was developed to examine the activity of potential anti-HBV compounds in chronic HBV-producing HepG2-derived 2.2.15 cells. Cell culture, immunoaffinity purification, polymerase chain reaction, and hybrid-capture detection were performed in the microtiter format to facilitate increased throughput by automation. The high sensitivity afforded by the assay provided quantitative detection of less than 0.5 fg of extracellular HBV DNA from 25 microliters of cell culture supernatants, and drug-induced reductions in HBV titers greater than 100-fold were easily measured. Fluorometric determination of total cellular DNA from the same 96-well proliferating cell cultures allowed simultaneous evaluation of inhibition of cell growth, thus providing the ability to assess the overall selectivities of candidate compounds in a single experiment. The potent activities of three anti-HBV compounds, the (+) and (-) enantiomers of cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxythiolane-5-yl]cytosine (FTC) and D-carbocyclic-2'-deoxyguanosine (CDG), were confirmed by this method. (-)-FTC was more active than its (+) enantiomer (50% inhibitory concentrations, 0.033 +/- 0.006 and 0.723 +/- 0.160 microM [standard error of the mean; SEM], respectively), while both enantiomers demonstrated a lack of cytotoxicity at 200 microM. CDG was more potent (50% inhibitory concentration, 0.0063 +/- 0.0007 microM [SEM]) but was also significantly more toxic, inhibiting cell growth by 50% at 32 +/- 6 microM (SEM). These results demonstrate the usefulness of this immunoaffinity-based, quantitative polymerase chain reaction system as a high-capacity in vitro tool for assessment of anti-HBV compound selectivity.
Oral enoxacin for infection prevention in adults with acute nonlymphocytic leukemia. The Enoxacin Prophylaxis Study Group
Authors: Talbot G H , Cassileth P A , Paradiso L , Correa-Coronas R , Bond L
Published: June 2012

A randomized, double-blind, placebo-controlled trial was conducted in eight hematologic units to determine the efficacy and safety of oral enoxacin for infection prevention in adult patients with acute nonlymphocytic leukemia. One hundred nineteen patients undergoing remission induction or consolidation chemotherapy were enrolled; 62 of them received enoxacin (400 mg orally every 12 h). Patients received antifungal prophylaxis with oral mycostatin (1,000,000 U four times daily) or clotrimazole (1 troche five times daily). Analysis was performed on an intent-to-treat basis. There was no significant difference between groups in race, age, or type and stage of leukemia, but there were more males in the placebo group (P = 0.073 [Fisher's exact test]). Fewer enoxacin patients had gram-negative bacteremia (1 versus 14 [P < 0.001]), gram-negative infection at any site (2 versus 19 [P < 0.001]), or bacterial and/or fungal infection (17 versus 26 [P = 0.056]). There was no significant difference in the number of patients with gram-positive infection at any site (12 versus 16), gram-positive bacteremia (9 versus 10), deep fungal infection (6 versus 2), death (2 versus 3), other antimicrobial therapy required (48 versus 48), therapy with amphotericin B (15 versus 7 [P = 0.105]), any adverse event (45 versus 36), or any study drug-associated adverse events (13 versus 6). Logistic regression confirmed (odds ratios and 95% confidence intervals are given in parentheses) that enoxacin reduced the risk of gram-negative infection (0.07; 0.01 to 0.30), especially gram-negative bacillary bacteremia (0.05; 0.01 to 0.37), without altering the risk of gram-positive bacterial (0.63; 0.26 to 1.5), deep fungal (2.57; 0.47 to 13.9), or Clostridium difficile (1.16; 0.3 to 4.56) infection. The median time to the onset of fever of more than or equal 102.8 F (39.3 degree C) was 32 days for the enoxacin group versus 15 days for patients receiving placebo (P=0.0007 [Wilcoxon test]). In patients with acute nonlymphocytic leukemia, oral enoxacin prevents gram-negative infections, delays the onset of fever, does not alter the incidence of gram-positive or proven deep fungal infections, and is well tolerated.
Treatment of acute uncomplicated urinary tract infections with 3 days of lomefloxacin compared with treatment with 3 days of norfloxacin
Authors: Nicolle L E , DuBois J , Martel A Y , Harding G K , Shafran S D , Conly J M
Published: June 2012

The bacteriologic and clinical efficacies of 3 days of lomefloxacin therapy were compared with those of 3 days of norfloxacin therapy for the treatment of acute uncomplicated urinary tract infections in a prospective, randomized, double-blind study. One hundred sixty-four subjects were enrolled at five Canadian centers; 84 received lomefloxacin, and 80 received norfloxacin. Escherichia coli (84%) and Staphylococcus saprophyticus (11%) were the most common organisms isolated. Forty subjects (24%) had low quantitative counts in their pretherapy urine specimens. In the intent-to-treat analysis, 76 lomefloxacin subjects (91%) and 76 norfloxacin subjects (95%) were cured or improved at follow-up 5 to 9 days posttreatment and 73 (87%) and 71 (89%) subjects from the lomefloxacin and norfloxacin groups, respectively, were cured or improved at 4 to 6 weeks posttreatment. Bacteriologic eradication occurred in 61 of 63 lomefloxacin subjects (97%) with > or = 10(8) CFU/liter in their pretherapy specimens and 56 of 59 norfloxacin subjects (95%) at 5 to 9 days and 55 (87%) and 53 (90%) subjects from the lomefloxacin and norfloxacin groups, respectively, at 4 to 6 weeks. There were no statistically significant differences in outcome. Adverse effects which were potentially related to the study medications were reported by 26% of the subjects who received lomefloxacin and 25% of the subjects who received norfloxacin. There were no severe adverse events, and only one subject discontinued therapy. These data suggest that 3 days of therapy with either lomefloxacin or norfloxacin is effective in the treatment of acute uncomplicated urinary tract infections.
Mevinolin (lovastatin) potentiates the antiproliferative effects of ketoconazole and terbinafine against Trypanosoma (Schizotrypanum) cruzi: in vitro and in vivo studies
Authors: Urbina J A , Lazardi K , Marchan E , Visbal G , Aguirre T , Piras M M , Piras R , Maldonado R A , Payares G , de Souza W
Published: June 2012

We have studied the antiproliferative effects of mevinolin (lovastatin), an inhibitor of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase, on the protozoan parasite Trypanosoma (Schizotrypanum) cruzi and its ability to potentiate the action of specific ergosterol biosynthesis inhibitors, such as ketoconazole and terbinafine, both in vitro and in vivo. Against the epimastigote form in vitro, mevinolin produced a dose-dependent reduction of the growth rate up to 25 microM, but at 50 and 75 microM, complete growth arrest and cell lysis took place after 144 and 96 h, respectively. A systematic study of the effects of mevinolin combined with ketoconazole and terbinafine, which act at different points in the ergosterol biosynthesis pathway, on the proliferation of epimastigotes indicated a synergic action, as shown by concave isobolograms and fractional inhibitory concentration indexes ranging from 0.17 to 0.54. Analysis of the sterol composition and de novo sterol synthesis in control and treated cells by thin-layer and gas-liquid chromatographies showed that the antiproliferative effects of the drug alone and in combination were correlated with the depletion of the endogenous ergosterol pool and particularly with a critical (exogenous) cholesterol/endogenous 4-desmethyl sterol ratio in the cells. When we studied the effects of mevinolin on the amastigote form proliferating inside Vero cells in vitro, only very modest effects on the parasites were observed up to 0.75 microM; above this concentration, significant deleterious effects on the host cells were found. However, when the same concentration of the drug was combined with ketoconazole, it was able to reduce by a factor of 10 the concentration of the azole required to eradicate the parasite (from 10 to 1 nM), again indicating a synergic action. On the other hand, a combination of mevinolin and terbinafine had only additive effects on amastigotes, but a ternary combination of mevinolin, ketoconazole, and terbinafine was again clearly synergistic. In vivo studies with a murine model of Chagas' disease showed that mevinolin can also potentiate the therapeutic effects of ketoconazole in this system; combined treatment with the two drugs at doses that alone offered only limited protection against the parasite was able to essentially eliminate circulating parasites and produce complete protection against death. These results confirm the synergic action against the proliferative stages of T. cruzi both in vitro and in vivo and in vivo of combined ergosterol biosynthesis inhibitors that act at different points in the pathway and suggest that mevinolin combined with azoles, such as ketoconazole, can be used in the treatment of human Chagas' disease.
Doxycycline in the protection of serum alpha-1-antitrypsin from human neutrophil collagenase and gelatinase
Authors: Sorsa T , Lindy O , Konttinen Y T , Suomalainen K , Ingman T , Saari H , Halinen S , Lee H M , Golub L M , Hall J
Published: June 2012

The concentration of doxycycline required to inhibit 50% (50% inhibitory concentration for serpinase activity) of alpha-1-antitrypsin degradation by purified neutrophil collagenase was found to be approximately 20 microM, a value similar to the 50% inhibitory concentration of doxycycline required to inhibit collagen degradation by neutrophil collagenase. Doxycycline also efficiently inhibited phorbol myristate acetate-triggered neutrophil-mediated degradation of alpha-1-antitrypsin. This suggests that doxycycline can protect alpha-1-antitrypsin from collagenase and gelatinase in the presence of other proteases and biologically active molecules that are released by triggered neutrophils. The protection of a body's alpha-1-antitrypsin shield from serpinolytic activity of collagenase and matrix metallproteinases can result in inhibition of serine proteases such as neutrophil elastase. Tetracyclines may thus protect matrix constituents from a wider spectrum of neutral proteases than previously recognized, not just from the matrix metalloproteinases collagenase and gelatinase.
Efficacy and ocular penetration of sparfloxacin in experimental streptococcal endophthalmitis
Authors: Cochereau-Massin I , Bauchet J , Marrakchi-Benjaafar S , Saleh-Mghir A , Faurisson F , Vallois J M , Vallee E , Pocidalo J J
Published: June 2012

Gram-positive cocci are the most common pathogens in severe human eye infections. Streptococcal endophthalmitis is a devastating infection, and intravitreal antibiotic therapy is limited by retinal toxicity. Because few systemic antistreptococcal antibiotics penetrate into the vitreous, sparfloxacin, a newer quinolone with improved antistreptococcal activity, might be of interest. We therefore assessed its efficacy by the intravitreal route in a rabbit model of streptococcal endophthalmitis. The vitreal bacterial count (mean +/- standard deviation log10 CFU per milliliter) was significantly reduced after an intravitreal injection of 800 micrograms of sprafloxacin (4.9 +/- 0.7) relative to the counts in untreated control (7.1 +/- 0.7) and pefloxacin-treated (7.8 +/- 1.2) eyes. After systemic administration to rabbits, the maximum concentration of sparfloxacin in serum was 5.6 micrograms.ml-1 and the half-life was 7.5 h. Sparfloxacin exhibited very good penetration ratios in the vitreous (54%), cornea (76%), and lens (36%). In the vitreous, the levels of sparfloxacin remained greater than the MICs for most gram-positive cocci for up to 18 h. Further experimental studies are warranted to determine the efficacy of systemic sparfloxacin as adjuvant therapy in the treatment of human endophthalmitis.
Pharmacokinetics of rufloxacin in patients with impaired renal function
Authors: Perry G , Mant T G , Morrison P J , Sacks S , Woodcook J , Wise R , Imbimbo B P
Published: June 2012

The pharmacokinetics of rufloxacin were investigated in normal subjects and in patients with various degrees of renal failure after the administration of a single oral 400-mg dose. Twenty-four subjects were classified by glomerular filtration rate (GFR) normalized for body surface area. Group 1 subjects had GFRs of > 80 ml/min, group 2 subjects had GFRs from 30 to 80 ml/min, group 3 subjects had GFRs from 8 to 29 ml/min, and group 4 subjects had GFRs of < 8 ml/min. The patients in group 4 were on continuous peritoneal dialysis or underwent hemodialysis 48 h after dosing. Plasma and urinary rufloxacin concentrations were determined by high-performance liquid chromatography. A two-compartment model was used to calculate rufloxacin pharmacokinetic parameters. Apparent total body clearance of the drug was linearly related to GFR (r = 0.696; P < 0.01). The elimination half-life increased proportionally with the severity of renal impairment, with values of 30 +/- 3, 36 +/- 5, and 44 +/- 3 h in groups 1, 2, and 3, respectively. In patients with moderate renal failure, dosage adjustment of rufloxacin is not needed. The rufloxacin dose interval should be prolonged to 48 h as the GFR falls below 30 ml/min/1.73 m2.
Effects of temperature on anti-Candida activities of antifungal antibiotics
Authors: Odds F C
Published: June 2012

The relative growth (percentage of growth relative to control growth) of 767 Candida isolates representing five species was measured in microcultures at 25 and 37 degrees C. In the presence of 10(-4) M flucytosine, the distribution of relative yeast growth data indicated that Candida albicans isolates were less susceptible at 25 degrees C than at 37 degrees C, while the opposite was found with 4 x 10(-5) M amorolfine for most of the isolates tested. Repetition of the experiments at four different temperatures with 99 C. albicans isolates and five antifungal agents confirmed a direct relationship between growth inhibition and increasing temperature from 25 to 40 degrees C with amphotericin B, flucytosine, and terconazole; a strong inverse relationship between inhibition and temperature with amorolfine; and a weak inverse relationship with terbinafine. However, these relationships were not always noted with other Candida spp.: in particular, the growth of C. glabrata and C. parapsilosis isolates tended to be greater at 37 degrees C than at 25 degrees C in the presence of the azole-derivative antifungal agents itraconazole and terconazole. These findings stress the species-specific individuality of yeast susceptibility to azole antifungal agents. The results with C. albicans and amorolfine and terbinafine accord with their known in vivo efficacy in mycoses involving low-temperature superficial sites and poor activity against mycoses involving deep body sites. The data also reinforce the need for control of experimental variables such as temperature in the design of standardized yeast susceptibility tests.
Mutations in the gyrA gene of a highly fluoroquinolone-resistant clinical isolate of Escherichia coli
Authors: Heisig P , Schedletzky H , Falkenstein-Paul H
Published: June 2012

We have determined the DNA sequence of the gyrA gene of the fluoroquinolone-resistant Escherichia coli isolate 205096 (MIC of ciprofloxacin, 128 micrograms/ml), which was recently demonstrated to be a gyrA mutant (P. Heisig and B. Wiedemann, Antimicrob. Agents Chemother. 35:2031-2036, 1991). Compared with the gyrA+ gene of E. coli K-12, 55 nucleotide changes were found. Three of these resulted in amino acid exchanges: Ser-83-->Leu, Asp-87-->Gly, and Asp-678-->Glu. A 0.7-kb DNA fragment containing two of these mutations (Ser-83-->Leu and Asp-87-->Gly) was isolated and fused in frame to the residual 3' coding region of gyrA+ in a plasmid to yield a chimeric gyrA gene (gyrA#). After introduction into E. coli 205096, this gyrA# gene does not increase the fluoroquinolone susceptibility of the resulting heterodiploid strain in a dominance test, while the gyrA+ gene does. The ciprofloxacin concentration necessary to inhibit by 90% (IC90) the supercoiling activity of gyrase isolated from E. coli 205096 is above 2,000 micrograms/ml. An identical result was found for gyrase reconstituted in vitro from the gyrB+ gene product and the chimeric gyrA# gene product. This is more than a 4,000-fold increase compared with the IC90 determined for gyrase from E. coli K-12 (gyrA+) (IC90, 0.5 microgram of ciprofloxacin per ml). No indications for the involvement of the gyrB gene or for alterations in quinolone permeation were found.
Nucleotide sequence analysis and DNA hybridization studies of the ant(4')-IIa gene from Pseudomonas aeruginosa
Authors: Shaw K J , Munayyer H , Rather P N , Hare R S , Miller G H
Published: June 2012

The ant(4')-IIa gene was previously cloned from Pseudomonas aeruginosa on a 1.6-kb DNA fragment (G. A. Jacoby, M. J. Blaser, P. Santanam, H. Hächler, F. H. Kayser, R. S. Hare, and G. H. Miller, Antimicrob. Agents Chemother. 34:2381-2386, 1990). In the current study, the ant(4')-IIa gene was localized by gamma-delta mutagenesis. A region of approximately 600 nucleotides which contained the ant(4')-IIa gene was identified, and DNA sequence analysis revealed two overlapping open reading frames (ORFs) within this region. Northern (RNA) blot analysis demonstrated expression of both ORFs in P. aeruginosa; therefore, site-directed mutagenesis was used to identify the ORF which encodes the ant(4')-IIa gene. No homology was found between ant(4')-IIa and ant(4')-Ia DNA sequences. Hybridization experiments confirmed that the ant(4')-Ia probe hybridized only to gram-positive presumptive ANT(4')-I strains and that the ant(4')-IIa probe hybridized only to gram-negative strains presumed to carry ANT(4')-II. Seven gram-negative strains which had been classified as having ANT(4')-II resistance profiles did not hybridize with probes for either ant(4')-Ia or ant(4')-IIa, suggesting that at least one additional ant(4') gene may exist. The predicted amino-terminal sequences of the ANT(4')-Ia and ANT(4')-IIa proteins showed significant sequence similarity between residues 38 and 63 of the ANT(4')-Ia protein and residues 26 and 51 of the ANT(4')-IIa protein.
Interaction of gentamicin with the A band and B band lipopolysaccharides of Pseudomonas aeruginosa and its possible lethal effect
Authors: Kadurugamuwa J L , Lam J S , Beveridge T J
Published: June 2012

The lipopolysaccharide (LPS) of Pseudomonas aeruginosa PAO1 possesses two distinct types of O polysaccharide, A and B band LPSs, but the majority of clinical isolates from cystic fibrosis patients who are infected with the organism possess only the A band as the major LPS antigen. The initial step in a series of events during the uptake of aminoglycoside antibiotics such as gentamicin is the ionic binding of the molecule to the cell surface. In an attempt to elucidate the role of A and B band LPSs of P. aeruginosa in this passive ionic binding of gentamicin to the outer membrane and its possible lethal effects, strains PAO1 (A+B+) and LPS isogenic derivatives (A+B-,A-B+,A-B-) were treated with the antibiotic. Ionic binding of gentamicin appeared to be subtly different in PAO1 and its LPS derivatives; a lethal dose of drug was bound to all strains, although the degree of binding varied with each strain. The outer membrane affinity for gentamicin was higher in strains possessing the B band than in strains with A band LPS, and these B band strains were more prone to antibiotic-induced killing. Strains with both A and B band LPSs bound the most gentamicin of all strains, and this binding caused an almost 50% loss in viability. Ionic binding of aminoglycoside antibiotucs to the outer membrane of cell surfaces must not only weaken th cell surface (R. E. W. Hancock, Annu. Rev. Microbiol. 38:237-264, 1984; N. L. Martin and T. J. Beveridge, Antimicrob. Agents Chemother. 29:1079-1087, 1986; S. G. Walker and T. J. Beveridge, Can. J. Microbiol. 34:12-18, 1988) but it must also be more important in cell death than was originally thought.