Potent synergistic combination of rosuvastatin and levofloxacin against Staphylococcus aureus: in vitro and in vivo study

Repositioning of HMG-CoA Reductase Inhibitors as Adjuvants in the Modulation of Efflux Pump-Mediated Bacterial and Tumor Resistance

Efflux pump (EP)-mediated multidrug resistance (MDR) seems ubiquitous in bacterial infections and neoplastic diseases. The diversity and lack of specificity of these efflux mechanisms raise a great obstacle in developing drugs that modulate efflux pumps. Since developing novel chemotherapeutic drugs requires large investments, drug repurposing offers a new approach that can provide alternatives as adjuvants in treating resistant microbial infections and progressive cancerous diseases. Hydroxy-methyl-glutaryl coenzyme-A (HMG-CoA) reductase inhibitors, also known as statins, are promising agents in this respect. Originally, statins were used in the therapy of dyslipidemia and for the prevention of cardiovascular diseases; however, extensive research has recently been performed to elucidate the functions of statins in bacterial infections and cancers. The mevalonate pathway is essential in the posttranslational modification of proteins related to vital eukaryotic cell functions. In this article, a comparative review is given about the possible role of HMG-CoA reductase inhibitors in managing diseases of bacterial and neoplastic origin. Molecular research and clinical studies have proven the justification of statins in this field. Further well-designed clinical trials are urged to clarify the significance of the contribution of statins to the lower risk of disease progression in bacterial infections and cancerous diseases.

Antibacterial, antibiofilm, and anti-quorum sensing activities of pyocyanin against methicillin-resistant Staphylococcus aureus: in vitro and in vivo study

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) infections are considered a major public health problem, as the treatment options are restricted. Biofilm formation and the quorum sensing (QS) system play a pivotal role in S. aureus pathogenicity. Hence, this study was performed to explore the antibacterial effect of pyocyanin (PCN) on MRSA as well as its effect on MRSA biofilm and QS.

RESULTS

Data revealed that PCN exhibited strong antibacterial activity against all test MRSA isolates (n = 30) with a MIC value equal to 8 µg/ml. About 88% of MRSA biofilms were eradicated by PCN treatment using the crystal violet assay. The disruption of MRSA biofilm was confirmed using confocal laser scanning microscopy, which showed a reduction in bacterial viability (approximately equal to 82%) and biofilm thickness (approximately equal to 60%). Additionally, the disruption of the formation of microcolonies and the disturbance of the connection between bacterial cells in the MRSA biofilm after PCN treatment were examined by scanning electron microscopy. The 1/2 and 1/4 MICs of PCN exerted promising anti-QS activity without affecting bacterial viability; Agr QS-dependent virulence factors (hemolysin, protease, and motility), and the expression of agrA gene, decreased after PCN treatment. The in silico analysis confirmed the binding of PCN to the AgrA protein active site, which blocked its action. The in vivo study using the rat wound infection model confirmed the ability of PCN to modulate the biofilm and QS of MRSA isolates.

CONCLUSION

The extracted PCN seems to be a good candidate for treating MRSA infection through biofilm eradication and Agr QS inhibition.

Exploring the potential efficacy of phage therapy for biocontrol of foodborne pathogenic extensively drug-resistant Escherichia coli in gastrointestinal tract of rat model

AIM

The emergence of extensively drug-resistant (XDR) Escherichia coli leaves little or no therapeutic options for the control of these foodborne pathogens. The goal is to isolate, characterize, and assess the potential efficacy of a bacteriophage in the treatment of an induced gastrointestinal tract infection.

MAIN METHODS

Sewage water was used to isolate phage phPE42. Transmission electron microscope was used for the visualization of phage morphology. Lysis profile, growth kinetics, and stability studies were determined. The ability of phage to eradicate biofilms was assessed by crystal violet staining, resazurin assay, compound bright field microscope, and confocal laser scanning microscope (CLSM). Moreover, the efficacy of phage phPE42 as a potential therapy was evaluated in a rat model.

KEY FINDINGS

A newly lytic Myoviridae phage phPE42 was isolated and exhibited broad coverage activity (48.6 %) against E. coli clinical isolates. It demonstrated favorable growth kinetics and relative stability under a variety of challenging conditions. The resazurin colorimetric assay and CLSM provided evidence of phage potential's ability to significantly (P < 0.05) decrease the viability of biofilm-embedded cells. The bacterial burden in animal faeces was effectively eradicated (P < 0.05) by oral administration of phage phPE42. Phage-treated rats exhibited a significant decrease in tissue damage with no signs of inflammation, necrosis, or erosion. Furthermore, phage therapy significantly (P < 0.05) reduced the expression level of the apoptotic marker caspase-3 and the inflammatory cytokine TNF-α.

SIGNIFICANCE

Treatment with phage phPE42 is considered a promising alternative therapy for the control of severe foodborne infections spurred by pathogenic XDR E. coli.

The promising anti-virulence activity of candesartan, domperidone, and miconazole on Staphylococcus aureus

Staphylococcus aureus is a primary cause of hospital and community-acquired infections. With the emergence of multidrug-resistant S. aureus strains, there is a need for new drugs discovery. Due to the poor supply of new antimicrobials, targeting virulence of S. aureus may generate weaker selection for resistant strains, anti-virulence agents disarm the pathogen instead of killing it. In this study, the ability of the FDA-approved drugs domperidone, candesartan, and miconazole as inhibitors of S. aureus virulence was investigated. The effect of tested drugs was evaluated against biofilm formation, lipase, protease, hemolysin, and staphyloxanthin production by using phenotypic and genotypic methods. At sub-inhibitory concentrations, candesartan, domperidone, and miconazole showed a significant inhibition of hemolysin (75.8-96%), staphyloxanthin (81.2-85%), lipase (50-65%), protease (40-64%), and biofilm formation (71.4-90%). Domperidone and candesartan have similar activity and were more powerful than miconazole against S. aureus virulence. The hemolysins and lipase inhibition were the greatest under the domperidone effect. Candesartan showed a remarkable reduction in staphyloxanthin production. The highest inhibitory effect of proteolytic activity was obtained with domperidone and candesartan. Biofilm was significantly reduced by miconazole. Expression levels of crtM, sigB, sarA, agrA, hla, fnbA, and icaA genes were significantly reduced under candesartan (68.98-82.7%), domperidone (62.6-77.2%), and miconazole (32.96-52.6%) at sub-MIC concentrations. Candesartan showed the highest inhibition activity against crtM, sigB, sarA, agrA, hla, and icaA expression followed by domperidone then miconazole. Domperidone showed the highest downregulation activity against fnbA gene. In conclusion, candesartan, domperidone, and miconazole could serve as anti-virulence agents for attenuation of S. aureus pathogenicity.