<i>In Vitro</i> Activity of RX-P873 against Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter baumannii
Bibliographic record
Abstract
RX-P873 is a novel antibiotic from the pyrrolocytosine series which exhibits high binding affinity for the bacterial ribosome and broad-spectrum antibiotic properties. The pyrrolocytosines have shown in vitro activity against multidrug-resistant Gram-negative and Gram-positive strains of bacteria known to cause complicated urinary tract, skin, and lung infections, as well as sepsis. Enterobacteriaceae (657), Pseudomonas aeruginosa (200), and Acinetobacter baumannii (202) isolates from North America and Europe collected in 2012 as part of a worldwide surveillance program were tested in vitro by broth microdilution using Clinical and Laboratory Standards Institute (CLSI) methodology. RX-P873 (MIC90, 0.5 μg/ml) was >32-fold more active than ceftazidime and inhibited 97.1% and 99.5% of Enterobacteriaceae isolates at MIC values of ≤1 and ≤4 μg/ml, respectively. There were only three isolates with an MIC value of >4 μg/ml (all were indole-positive Protea). RX-P873 (MIC50/90, 2/4 μg/ml) was highly active against Pseudomonas aeruginosa isolates, including isolates which were nonsusceptible to ceftazidime or meropenem. RX-P873 was 2-fold less active against P. aeruginosa than tobramycin (MIC90, 2 μg/ml; 91.0% susceptible) and colistin (MIC90, 2 μg/ml; 99.5% susceptible) and 2-fold more potent than amikacin (MIC90, 8 μg/ml; 93.5% susceptible) and meropenem (MIC90, 8 μg/ml; 76.0% susceptible). RX-P873, the most active agent against Acinetobacter baumannii (MIC90, 1 μg/ml), was 2-fold more active than colistin (MIC90, 2 μg/ml; 97.0% susceptible) and 4-fold more active than tigecycline (MIC90, 4 μg/ml). This novel agent merits further exploration of its potential against multidrug-resistant Gram-negative bacteria.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".