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Angela M Nilius

Publications and source records attributed to Angela M Nilius.

At least 19 recordsLinked to original sources
PubMed2006

Novel antibacterial class: a series of tetracyclic derivatives.

We describe the synthesis and antibacterial activity of a series of tetracyclic naphthyridones. The members of this series act primarily via inhibition of bacterial translation and belong to the class of novel ribosome inhibitors (NRIs). In this paper we explore the structure-activity relationships (SAR) of these compounds to measure their ability both to inhibit bacterial translation and also to inhibit the growth of bacterial cells in culture. The most active of these compounds inhibit Streptococcus pneumoniae translation at concentrations of <5 microM and have minimum inhibitory concentrations (MICs) of <8 microg/mL against clinically relevant strains of bacteria.

Anti-Bacterial Agents↗
PubMed2006

Efficacy, tolerability, and parent reported outcomes for cefdinir vs. high-dose amoxicillin/clavulanate oral suspension for acute otitis media in young children.

OBJECTIVES: To compare efficacy, tolerability, and parental satisfaction of cefdinir and high-dose amoxicillin/clavulanate oral suspensions given to young children with non-refractory acute otitis media (AOM) based on clinical endpoints and outcomes measures. RESEARCH DESIGN AND METHODS: This was an investigator-blinded, multicenter study in which 318 children 6 months through 6 years of age with a clinical diagnosis of AOM were randomized to receive 10 days of either cefdinir (14 mg/kg divided BID) or high-dose amoxicillin/clavulanate (90/6.4 mg/kg divided BID). MAIN OUTCOME MEASURES: Investigators evaluated clinical response at an end-of-therapy (EOT) office visit conducted on day 12-15. Outcomes of satisfaction, tolerability, and adherence were also assessed at that visit using an Otitis Parent Questionnaire. RESULTS: The treatment groups were similar at baseline with respect to patient demographics. At the EOT visit, for cefdinir and amoxicillin/clavulanate, respectively, intent-to-treat (ITT) clinical cure rates were 82% (129/158) and 85% (134/158) (p = 0.547; 95% confidence interval [CI] -11.7 to 5.4) and per-protocol cure rates were 82% (123/150) and 90% (129/143) (p = 0.045; 95% CI -16.4 to 0.0). This difference was driven primarily by reduced cefdinir response in patients with recurrent AOM (p = 0.010) and those younger than 24 months (p = 0.039). Comparing cefdinir with amoxicillin/clavulanate, parents more often reported significantly better ease of use (89% vs. 57%; p < 0.0001), better taste (85% vs. 39%; p < 0.0001), and better adherence (at least 95% of doses) (82% vs. 61%; p < 0.0001). Diarrhea/loose stools were more common in the amoxicillin/clavulanate group than in the cefdinir group (28% vs. 18%, respectively; p = 0.0341). One patient in the cefdinir group and eight patients in the amoxicillin/clavulanate group withdrew from the study prematurely due to at least one adverse event (p = 0.0364). Study limitations included assessment of clinical recurrence by telephone call rather than office visit, exclusion of children with refractory AOM, and no assessment of middle ear microbiology. CONCLUSIONS: Among young children with non-refractory AOM, cefdinir was as efficacious as high-dose amoxicillin/clavulanate in the ITT group, but somewhat less effective in per-protocol analysis. From the parental perspective, cefdinir was easier to administer, had a better taste, caused less diarrhea, and resulted in higher treatment adherence than high-dose amoxicillin clavulanate.

Acute Disease↗
PubMed2005

Synthesis and antibacterial activity of 5-methoxy- and 5-hydroxy-6-fluoro-1,8-naphthyridone-3-carboxylic acid derivatives.

A series of 5-methoxy- and 5-hydroxy-6-fluoro-1,8-naphthyridone-3-carboxylic acid derivatives were prepared and evaluated for cell-free bacterial protein synthesis inhibition and whole cell antibacterial activity. When compared to the analogous 5-hydrogen compounds, the presence of the 5-OH group negatively affects biochemical potency. However, a tolerance of the 5-methoxy group is indicated. Only moderate whole cell antibacterial activity is seen, but this could be due to poor cellular penetration. Because only a few 7-position variants were made for this study, further investigation into this novel series combining a broader range of 7-amino derivatives with these 5-position modifications is warranted.

Anti-Bacterial Agents↗
PubMed2004

Novel inhibitors of bacterial protein synthesis: structure-activity relationships for 1,8-naphthyridine derivatives incorporating position 3 and 4 variants.

Structure-activity relationships for a recently discovered novel ribosome inhibitor (NRI) class of antibacterials were investigated. Preliminary efforts to optimize protein synthesis inhibitory activity of the series through modification of positions 3 and 4 of the naphthyridone lead template resulted in the identification of several biochemically potent analogues. A lack of corresponding whole cell antibacterial activity is thought to be a consequence of poor cellular penetration as evidenced by the enhancement of activity observed for a lead analogue tested in the presence of a cell permeabilizing agent.

Anti-Bacterial Agents↗
PubMed2004

Elimination of antibacterial activities of non-peptide luteinizing hormone-releasing hormone (LHRH) antagonists derived from erythromycin A.

Antibacterial SAR for a series of macrolides derived from erythromycin A that are potent LHRH antagonists was developed in an attempt to eliminate the antibiotic activities of these compounds. Increasing the size of the alkyl substituents on the desosamine 3'-amine resulted in potent LHRH antagonists that were inactive against staphylococcal bacteria strains, and were significantly (>10-fold) less active against streptococcal bacteria strains. Complete elimination of antibacterial activities could be achieved by replacement of one or both methyl groups on the 3'-amine with a large alkyl substituent.

Animals↗
PubMed2004

Ribosome affinity and the prolonged molecular postantibiotic effect of cethromycin (ABT-773) in Haemophilus influenzae.

Cethromycin (ABT-773) is a new ketolide currently in clinical trials, for treatment of community acquired respiratory tract infections. The drug is active in vitro and in vivo against Haemophilus influenzae. In this study, the mechanism of action of cethromycin was investigated in H. influenzae. The drug effect was studied using in vitro transcription-translation and whole cell amino acid incorporation. Both cethromycin and erythromycin inhibit protein synthesis with similar potencies; cethromycin, however, had a prolonged molecular postantibiotic effect (PAE) compared with erythromycin which was consistent with previously reported microbiological data. Ribosome binding assay using ribosomes isolated from H. influenzae NP200 revealed that the ribosome binding affinity of cethromycin was more than 20-fold tighter than that of erythromycin. Studies of binding kinetics showed that the tight binding of cethromycin mainly contributed to the 20-fold slower dissociation from cells. Further studies showed cethromycin had a four-fold faster drug accumulation rate than erythromycin. Therefore, the tight binding of cethromycin with ribosomes likely contributed to the faster drug accumulation, slower dissociation from cells and prolonged molecular PAE of cethromycin for H. influenzae.

Anti-Bacterial Agents↗
PubMed2004

A strategy for discovery of novel broad-spectrum antibacterials using a high-throughput Streptococcus pneumoniae transcription/translation screen.

The authors report the development of a high-throughput screen for inhibitors of Streptococcus pneumoniae transcription and translation (TT) using a luciferase reporter, and the secondary assays used to determine the biochemical spectrum of activity and bacterial specificity. More than 220,000 compounds were screened in mixtures of 10 compounds per well, with 10,000 picks selected for further study. False-positive hits from inhibition of luciferase activity were an extremely common artifact. After filtering luciferase inhibitors and several known classes of antibiotics, approximately 50 hits remained. These compounds were examined for their ability to inhibit Escherichia coli TT, uncoupled S. pneumoniae translation or transcription, rabbit reticulocyte translation, and in vitro toxicity in human and bacterial cells. One of these compounds had the desired profile of broad-spectrum biochemical activity in bacteria and selectivity versus mammalian biochemical and whole-cell assays.

Anti-Bacterial Agents↗
PubMed2003

In vivo characterization of A-192411: a novel fungicidal lipopeptide (II).

The ability of the novel antifungal cyclic hexalipopetide A-192411 to treat fungal infections in rodents is presented. Efficacy was demonstrated against Candida albicans as both prolonged survival of systemically infected mice and clearance of viable yeasts from kidneys. The efficacy of A-192411, administered intraperitoneally, was equivalent to amphotercin B at a 4-fold lower dose by weight in the systemic candidiasis models in mice, while the efficacy of A-192441 administered intravenously was equivalent to amphotercin B by weight in the Candida pyelonephritis model in rats. A-192411 also slightly prolonged the survival of immunocompromised mice infected systemically with Aspergillus fumigatus.

Amphotericin B↗
PubMed2003

In vitro antibacterial potency and spectrum of ABT-492, a new fluoroquinolone.

ABT-492 demonstrated potent antibacterial activity against most quinolone-susceptible pathogens. The rank order of potency was ABT-492 > trovafloxacin > levofloxacin > ciprofloxacin against quinolone-susceptible staphylococci, streptococci, and enterococci. ABT-492 had activity comparable to those of trovafloxacin, levofloxacin, and ciprofloxacin against seven species of quinolone-susceptible members of the family Enterobacteriaceae, although it was less active than the comparators against Citrobacter freundii and Serratia marcescens. The activity of ABT-492 was greater than those of the comparators against fastidious gram-negative species, including Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, and Legionella spp. and against Pseudomonas aeruginosa and Helicobacter pylori. ABT-492 was as active as trovafloxacin against Chlamydia trachomatis, indicating good intracellular penetration and antibacterial activity. In particular, ABT-492 was more active than trovafloxacin and levofloxacin against multidrug-resistant Streptococcus pneumoniae, including strains resistant to penicillin and macrolides, and H. influenzae, including beta-lactam-resistant strains. It retained greater in vitro activity than the comparators against S. pneumoniae and H. influenzae strains resistant to other quinolones due to amino acid alterations in the quinolone resistance-determining regions of the target topoisomerases. ABT-492 was a potent inhibitor of bacterial topoisomerases, and unlike the comparators, DNA gyrase and topoisomerase IV from either Staphylococcus aureus or Escherichia coli were almost equally sensitive to ABT-492. The profile of ABT-492 suggested that it may be a useful agent for the treatment of community-acquired respiratory tract infections, as well as infections of the urinary tract, bloodstream, and skin and skin structure and nosocomial lung infections.

Animals↗
PubMed2003

Novel antibacterial class.

We report the discovery and characterization of a novel ribosome inhibitor (NRI) class that exhibits selective and broad-spectrum antibacterial activity. Compounds in this class inhibit growth of many gram-positive and gram-negative bacteria, including the common respiratory pathogens Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis, and are nontoxic to human cell lines. The first NRI was discovered in a high-throughput screen designed to identify inhibitors of cell-free translation in extracts from S. pneumoniae. The chemical structure of the NRI class is related to antibacterial quinolones, but, interestingly, the differences in structure are sufficient to completely alter the biochemical and intracellular mechanisms of action. Expression array studies and analysis of NRI-resistant mutants confirm this difference in intracellular mechanism and provide evidence that the NRIs inhibit bacterial protein synthesis by inhibiting ribosomes. Furthermore, compounds in the NRI series appear to inhibit bacterial ribosomes by a new mechanism, because NRI-resistant strains are not cross-resistant to other ribosome inhibitors, such as macrolides, chloramphenicol, tetracycline, aminoglycosides, or oxazolidinones. The NRIs are a promising new antibacterial class with activity against all major drug-resistant respiratory pathogens.

Amino Acyl-tRNA Synthetases↗
PubMed2003

PCR-oligonucleotide ligation assay for detection of point mutations associated with quinolone resistance in Streptococcus pneumoniae.

We have developed a PCR-oligonucleotide ligation assay to rapidly identify base substitutions in topoisomerase genes that are associated with quinolone resistance in clinical isolates of Streptococcus pneumoniae. Thirty-seven strains for which the ciprofloxacin MICs were >/=4 micro g/ml and 16 strains for which the MICs were </=2 micro g/ml were assayed. Compared with sequence data, the assay correctly identified the DNA bases that encoded amino acids at the four positions most commonly associated with quinolone resistance (Ser79 and Asp83 of ParC and Ser81 and Glu85 of GyrA). Therefore, this procedure can rapidly distinguish single base substitutions associated with quinolone-resistant topoisomerases in S. pneumoniae.

DNA Gyrase↗
PubMed2003

Have the oxazolidinones lived up to their billing? Future perspectives for this antibacterial class.

Linezolid was the first antibacterial oxazolidinone to be approved for clinical use. Oxazolidinones meet a growing medical need to treat multidrug-resistant, methicillin-resistant staphylococci, vancomycin-resistant enterococci, and penicillin-non-susceptible pneumococci in hospitalized patients. They also offer a treatment option for patients who are intolerant of vancomycin and other antibacterial agents, or who have infections that are refractory or resistant to other therapies. Two main concerns, however, have arisen as linezolid use has increased. The first is the incidence of myelosuppression, in particular thrombocytopenia, which appears to be greater than that seen during clinical trials. Secondly, linezolid-resistant Staphylococcus aureus and enterococci have emerged during linezolid treatment, which can be transmitted from patient-to-patient. This review will discuss the mechanism of action, the mechanism of resistance, and the antibacterial spectrum and potency of the oxazolidinones. In addition, the efficacy and safety of linezolid derived from clinical experience will be presented.

Acetamides↗