Methicillin resistant Staphylococcus aureus infective endocarditis presenting as neutrophilic meningoencephalitis

Transesophageal Echocardiography vs. Transthoracic Echocardiography for Methicillin-Sensitive Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus Endocarditis

Infective endocarditis is an infection of the inner layers of the heart, seen often in intravenous drug users and patients with valvular lesions or prosthetic heart valves. This entity has high mortality and morbidity. The most common causative microorganism is Staphylococcus aureus. In this comprehensive literature review, we focused on both Staphylococcus aureus infections, i.e., methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) endocarditis, demographics, use of transthoracic echocardiogram and/or transesophageal echocardiogram for diagnostics, and treatments. Although clinical criteria are relevant, transesophageal echocardiogram plays a vital role in establishing and identifying the presence of infective endocarditis and its local complications, with higher sensitivity in patients with prosthetic valves. The antibiotic selection posed a great challenge for clinicians due to antibiotic resistance and the aggressive nature of Staphylococcus aureus. Early diagnosis of infective endocarditis, when suspected, and effective management by a multispecialty team can improve the outcome for the patients.

The Antibacterial Activity Mode of Action of Plantaricin YKX against Staphylococcus aureus

We aimed to evaluate the inhibitory effect and mechanism of plantaricin YKX on S. aureus. The mode of action of plantaricin YKX against the cells of S. aureus indicated that plantaricin YKX was able to cause the leakage of cellular content and damage the structure of the cell membranes. Additionally, plantaricin YKX was also able to inhibit the formation of S. aureus biofilms. As the concentration of plantaricin YKX reached 3/4 MIC, the percentage of biofilm formation inhibition was over 50%. Fluorescent dye labeling combined with fluorescence microscopy confirmed the results. Finally, the effect of plantaricin YKX on the AI-2/LuxS QS system was investigated. Molecular docking predicted that the binding energy of AI-2 and plantaricin YKX was −4.7 kcal/mol and the binding energy of bacteriocin and luxS protein was −183.701 kcal/mol. The expression of the luxS gene increased significantly after being cocultured with plantaricin YKX, suggesting that plantaricin YKX can affect the QS system of S. aureus.

Antibacterial Designs for Implantable Medical Devices: Evolutions and Challenges

The uses of implantable medical devices are safer and more common since sterilization methods and techniques were established a century ago; however, device-associated infections (DAIs) are still frequent and becoming a leading complication as the number of medical device implantations keeps increasing. This urges the world to develop instructive prevention and treatment strategies for DAIs, boosting the studies on the design of antibacterial surfaces. Every year, studies associated with DAIs yield thousands of publications, which here are categorized into four groups, i.e., antibacterial surfaces with long-term efficacy, cell-selective capability, tailored responsiveness, and immune-instructive actions. These innovations are promising in advancing the solution to DAIs; whereas most of these are normally quite preliminary “proof of concept” studies lacking exact clinical scopes. To help identify the flaws of our current antibacterial designs, clinical features of DAIs are highlighted. These include unpredictable onset, site-specific incidence, and possibly involving multiple and resistant pathogenic strains. The key point we delivered is antibacterial designs should meet the specific requirements of the primary functions defined by the “intended use” of an implantable medical device. This review intends to help comprehend the complex relationship between the device, pathogens, and the host, and figure out future directions for improving the quality of antibacterial designs and promoting clinical translations.

In cellulo synthesis of dendrimeric sensors for fluorescence-on imaging of bacterial phagocytosis

Methods for optical tracking of pathogen-host interactions are of biomedical significance. We herein have reported a high molecular weight pH sensor (Den-pH) that is assembled in bacteria and then stably trapped in bacteria irrespective of bacterial membrane potentials. Endowed with acidity-triggered red fluorescence, Den-pH allows signal-on tracking of S. aureus in phagocytosis by macrophages. Intra-bacterial formation of multifunctional optical probes, which offers the advantage of overcoming the liability of conventional potential-sensitive dyes to dissipate from stressed bacteria, offers a new tool to study stressed pathogens.