Activity of Gallium (III) Compounds Against Biofilms of Multidrug-Resistant Isolates of Acinetobacter baumanni
Bibliographic record
Abstract
Background. Acinetobacter baumannii is a clinically challenging pathogen due to the emergence of multidrug resistance and ability to form biofilms. Iron (III) is critical to both physiology and virulence which has promoted interests in the development and use of agents to target iron metabolism. Gallium (III) is an iron (III) mimetic with antimicrobial activity against multiple bacterial pathogens including A. baumannii. To date studies evaluating the activity of gallium against A. baumannii have focused on planktonic but not the biofilm phenotype. To address this gap, we evaluated in vitro the activity of gallium compounds, gallium nitrate (GaNO3) and gallium meso-/protoporphyrin (GaMP/GaPP), against biofilms of clinical isolates of A. baumannii. Methods. Bacterial isolates used in this study included a collection from the Trauma Infectious Disease Outcome Study (n = 12) and a reference strain of A. baumannii (ATCC 17978). Antimicrobial activity of gallium compounds against planktonic and biofilm bacteria was evaluated by performing broth microdilution assays in iron-limited medias, RPMI 1640 and 10% MHB-II. Microdilution assays consisted of exposing bacteria or formed 24 hour biofilms overnight to increasing concentrations (0.25-512 µM) of the gallium compounds in 96-well plates or individual wells of the Calgary Device. Concentrations reducing viability of planktonic and biofilm bacteria to 50% and 90% of the untreated control were reported as the minimum inhibitory concentration or biofilm eradication concentration 50 and 90 (MIC/MBEC50 and MIC/MBEC90), respectively. Results. Median IC50 and IC90 for GaNO3 were 64 µM/128 µM in MHBII and 128 µM/256 µM in RPMI, whereas IC50 and IC90 for GaMP and GaPP were 1 µM/2 µM and 2 µM/8 µM, respectively, with no observable difference seen with different media. The MBEC50 and MBEC90 for GaNO3, GaMP, and GaPP were 256 µM/512 µM, 16 µM/32 µM, and 128 µM/256 µM, respectively. Conclusion. Gallium (III) compounds have differential activity against MDR A. baumannii in planktonic and biofilm forms. The heme-conjugated gallium compounds (GaMP/GaPP) had the most potent in vitro activity. Further investigations should explore their potential role as novel anti-biofilm agents. Disclosures. All authors: No reported disclosures.
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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) | 0.000 | 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 | 0.000 |
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".