Screening of the Medicines for Malaria Venture Pandemic Response Box for Discovery of Antivirulent Drug against Pseudomonas aeruginosa

Evaluation of MMV Pandemic Response Box compounds to identify potent compounds against clinically relevant bacterial and fungal clinical isolates in vitro

Background

Multidrug resistant bacterial and fungal pathogens are resistant to a number of significant front-line drugs, hence, identification of new inhibitory agents to combat them is crucial. In this study, we aim to evaluate the activity of Pandemic Box compounds from Malaria Medicines Venture (MMV) against A. baumannii and P. aeruginosa bacterial, C. auris, C. albicans and A. niger fungal clinical isolates.

Methods

Isolates were initially screened with 201 antibacterial and 46 antifungal compounds (10 μM) using a microbroth dilution in triplicates to determine MIC. A persister assay was performed for bacterial pathogens.

Results

Out of 201 antibacterial compounds, twenty-nine and seven compounds inhibited the growth of A. baumannii and P. aeruginosa at 10 μM, respectively. MMV1580854, MMV1579788, eravacycline and epetraborole inhibited both the bacterial test isolates. In a persister assay, MMV1634390 showed complete bactericidal effect against A. baumannii. With antifungal activity compounds, C. auris responded to15 compounds, Six compounds inhibited C. albicans and one was effective against A. niger at 10 μM. The ratio of Minimum Fungicidal Concentration (MFC): Minimum Inhibitory Concentration (MIC) of MMV1782110 was 2 against C. auris. Eberconazole, amorolfine and luliconazole are fungicidal targeting C. albicans at a MFC: MIC ratio of 2.

Conclusion

Five compounds from MMV Pandemic Box were found to be inhibiting colistin and ceftazidime resistant A. baumannii clinical isolate, also against colistin and β-lactam resistant P. aeruginosa clinical isolate. MMV1634390 showed complete bactericidal effect against A. baumannii in a persister assay. MMV1782110, Eberconazole, amorolfine and luliconazole exhibited potent anti-fungal activity. Further investigations are warranted to identify the targets and mechanism.

Identifying Fast and Slow-Acting Antimalarial Compounds of Pandemic Response Box Against Blood-Stage Culture of Plasmodium falciparum 3D7

The evolving clinical resistance in Plasmodium falciparum and the spike in malarial cases after the COVID-19 outbreak has triggered a search for new antimalarials effective against multi-drug-resistant P. falciparum strains. In this study, we assessed the timing of action, either fast or slow-acting of 13 potent compounds of Pandemic Response Box (PRB) against blood-stage Pf3D7 strain by SYBR Green-I assay. The asynchronous culture of Pf3D7 was exposed to varying concentrations of 13 compounds, and IC50 values were determined at 12, 24, 48, 72, and 96 h. We identified four fast-acting compounds (MMV000008, MMV1593541, MMV020752, MMV396785) with rapid-growth inhibitory activity having IC50 values ≤ 0.3 µM at 12 and 24 h. Similarly, we determined nine slow-acting compounds (MMV159340, MMV1634492, MMV1581558, MMV689758, MMV1593540, MMV394033, MMV019724, MMV000725, MMV1557856) having IC50 values ≤ 0.5 µM at 72 and 96 h. Furthermore, the stage-specific action of the two most potent fast-acting compounds (MMV1593541 and MMV020752) against rings, trophozoites, and schizonts at 48 h of exposure revealed that ring-stage parasites showed reduced IC50 values compared to mature stage forms. Therefore, our study demonstrates for the first time the identification of the most potent fast and slow-acting compounds from PRB against blood-stage infection, suggesting its utility in clinics and considering it as a partner drug in combination therapies.

Screening of MMV pandemic response and pathogen box compounds against pan-drug-resistant Klebsiella pneumoniae to identify potent inhibitory compounds

Background

The recent emergence of pan-drug-resistant (PDR) K. pneumoniae strains hinders the success rate of treatment procedures for patients. High mortality, extended duration of hospitalization with high costs is associated with such infections. Discovery and identification of new drugs are inevitable to combat PDR clinical pathogens. We aim to identify and evaluate new compounds in vitro against a PDR clinical K. pneumoniae isolate using compounds of Pathogen Box and Pandemic Response Box from Medicines for Malaria Venture (MMV).

Methods

The PDR strain was initially screened with the 601 compounds from both Boxes at 10 ​μM concentration. Formation of dormant cells against the drug activity was assessed using persister assay. MIC was determined for the drugs inhibiting PDR K. pneumoniae during initial screening.

Results

Five compounds were identified to inhibit the test strain. MMV1580854 (94.60 ​%), MMV1579788 (94.65 ​%), MMV1578574 (eravacycline; 93.13 ​%), MMV1578566 (epetraborole; 95.29 ​%) and MMV1578564 (96.32 ​%) were able to exhibit a higher percentage of growth inhibition. Persisters were found to be growing in a range from 104 to 107 ​CFU/ml. Minimum inhibitory concentrations (MIC) of all compounds were ≥ 2 ​μM except for MMV1579788, which had a MIC of ≥ 5 ​μM.

Conclusion

Five novel compounds were identified against the highly evolved pan-drug-resistant K. pneumoniae. Among the five, epetraborole andMMV1578564 were identified as highly potent based on the persister frequency and MICs. The pan-drug resistant clinical isolate used in this study was found to be acting differently from the reference or wild type strains against the test compounds in a previous study.

Quorum sensing-mediated microbial interactions: Mechanisms, applications, challenges and perspectives

Microbial community in natural or artificial environments playes critical roles in substance cycles, products synthesis and species evolution. Although microbial community structures have been revealed via culture-dependent and culture-independent approaches, the hidden forces driving the microbial community are rarely systematically discussed. As a mode of cell-to-cell communication that modifies microbial interactions, quorum sensing can regulate biofilm formation, public goods secretion, and antimicrobial substances synthesis, directly or indirectly influencing microbial community to adapt to the changing environment. Therefore, the current review focuses on microbial community in the different habitats from the quorum sensing perspective. Firstly, the definition and classification of quorum sensing were simply introduced. Subsequently, the relationships between quorum sensing and microbial interactions were deeply explored. The latest progressives regarding the applications of quorum sensing in wastewater treatment, human health, food fermentation, and synthetic biology were summarized in detail. Finally, the bottlenecks and outlooks of quorum sensing driving microbial community were adequately discussed. To our knowledge, this current review is the first to reveal the driving force of microbial community from the quorum sensing perspective. Hopefully, this review provides a theoretical basis for developing effective and convenient approaches to control the microbial community with quorum sensing approaches.