Identification of Eltrombopag as a Repurposing Drug Against Staphylococcus epidermidis and its Biofilms

Antimicrobial and Antibiofilm Effects of Bithionol against Mycobacterium abscessus

Mycobacterium abscessus (M. abscessus) is a multidrug-resistant nontuberculous mycobacterium (NTM) that is responsible for a wide spectrum of infections in humans. The lack of effective bactericidal drugs and the formation of biofilm make its clinical treatment very difficult. The FDA-approved drug library containing 3048 marketed and pharmacopeial drugs or compounds was screened at 20 μM against M. abscessus type strain 19977 in 7H9 medium, and 62 hits with potential antimicrobial activity against M. abscessus were identified. Among them, bithionol, a clinically approved antiparasitic agent, showed excellent antibacterial activity and inhibited the growth of three different subtypes of M. abscessus from 0.625 μM to 2.5 μM. We confirmed the bactericidal activity of bithionol by the MBC/MIC ratio being ≤4 and the time-kill curve study and also electron microscopy study. Interestingly, it was found that at 128 μg/mL, bithionol could completely eliminate biofilms after 48h, demonstrating an outstanding antibiofilm capability compared to commonly used antibiotics. Additionally, bithionol could eliminate 99.9% of biofilm bacteria at 64 μg/mL, 99% at 32 μg/mL, and 90% at 16 μg/mL. Therefore, bithionol may be a potential candidate for the treatment of M. abscessus infections due to its significant antimicrobial and antibiofilm activities.

Surface-enhanced Raman spectroscopy for the characterization of pellets of biofilm forming bacterial strains of Staphylococcus epidermidis

BACKGROUND

Surface-enhanced Raman spectroscopy (SERS) is an effective tool for identifying biofilm forming bacterial strains. Biofilm forming bacteria are considered a major issue in the health sector because they have strong resistance against antibiotics. Staphylococcus epidermidis is commonly present on intravascular devices and prosthetic joints, catheters and wounds.

OBJECTIVES

To identify and characterize biofilm forming and non-biofilm forming bacterial strains, surface- enhanced Raman spectroscopy with principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) were used.

METHODS

Surface-enhanced Raman spectroscopy (SERS) with silver nanoparticles were employed for the analysis and characterization of biofilm forming bacterial strains. SERS is used to differentiate between non biofilm forming (five samples), medium biofilm forming (five samples) and strong biofilm forming (five samples) bacterial strains by applying silver nanoparticles (AgNPs) as SERS substrate. Principal component analysis (PCA) and Partial least square discriminant analysis (PLS-DA) were used to discriminate between non, medium and strong biofilm ability of bacterial strains.

RESULTS

Principal component analysis (PCA) and Partial least square discriminant analysis (PLS-DA) have been used to identify the biochemical differences in the form of SERS features which can be used to differentiate between biofilm forming and non-biofilm forming bacterial strains. PLS-DA provides successful differentiation and classification of these different strains with 94.5% specificity, 96% sensitivity and 89% area under the curve (AUC).

CONCLUSIONS

Surface-enhanced Raman spectroscopy can be utilized to differentiate between non, medium and strong biofilm forming bacterial strains.

Drug repurposing to overcome microbial resistance

Infections are a growing global threat, and the number of resistant species of microbial pathogens is alarming. However, the rapid development of cross-resistant or multidrug-resistant strains and the development of so-called 'superbugs' are in stark contrast to the number of newly launched anti-infectives on the market. In this review, I summarize the causes of antimicrobial resistance, briefly discuss different approaches to the discovery and development of new anti-infective drugs, and focus on drug repurposing strategy, which is discussed from all possible perspectives. A comprehensive overview of drugs of other indications tested for their in vitro antimicrobial activity to support existing anti-infective therapeutics is provided, including several critical remarks on this strategy of repurposing non-antibiotics to antibacterial drugs.

Repurposing Eltrombopag as an Antimicrobial Agent Against Methicillin-Resistant Staphylococcus aureus

Because of the excessive use of antibiotics, methicillin-resistant Staphylococcus aureus (MRSA) has become prevalent worldwide. Moreover, the formation of S. aureus biofilms often cause persistence and relapse of infections. Thus, the discovery of antibiotics with excellent antimicrobial and anti-biofilm activities is urgently needed. In the present study, eltrombopag (EP), a classic thrombopoietin receptor agonist, exhibited potential antimicrobial activity against S. aureus and its biofilms. Through our mechanistic studies, EP was found to interfere with proton motive force in S. aureus. The in vivo anti-infective efficacy of EP was further confirmed in the wound infection model, thigh infection model and peritonitis model by MRSA infection. In addition, the cytotoxicity of EP against mammalian cells and the in vivo toxicity of EP in animal models were not observed at the tested concentrations. Collectively, these results indicate that EP could be considered a potential novel antimicrobial agent against recalcitrant infections caused by MRSA.