Ultrasound for the diagnosis of infectious diseases: Approach to the patient at point of care and at secondary level

Point-of-care Ultrasound in Infectious Diseases: Current Insights and Future Perspectives

Point-of-care ultrasound (POCUS) is a safe, noninvasive technique performed at the patient's bedside, providing immediate results to the operator. It complements physical examination and facilitates clinical decision-making. In infectious diseases, POCUS is particularly valuable, offering an initial assessment in cases of suspected infection. It often leads to an early tentative diagnosis enabling the prompt initiation of antimicrobial treatment without the delay associated with traditional radiology. POCUS provides direct visualization of affected organs, assists in evaluating fluid balance, and facilitates various interventions, all while reducing patient discomfort. For infectious disease specialists, becoming proficient in POCUS is a critical future challenge, requiring dedicated training for effective utilization.

Enzyme-Triggered Transforming of Assembly Peptide-Modified Magnetic Resonance-Tuned Probe for Highly Sensitive Imaging of Bacterial Infection In Vivo

Confirming bacterial infection at an early stage and distinguishing between sterile inflammation and bacterial infection is still highly needed for efficient treatment. Here, in situ highly sensitive magnetic resonance imaging (MRI) bacterial infection in vivo based on a peptide-modified magnetic resonance tuning (MRET) probe (MPD-1) that responds to matrix metallopeptidase 2 (MMP-2) highly expressed in bacteria-infected microenvironments is achieved. MPD-1 is an assembly of magnetic nanoparticle (MNP) bearing with gadolinium ion (Gd3+ ) modified MMP-2-cleavable self-assembled peptide (P1 ) and bacteria-targeting peptide (P), and it shows T2 -weighted signal due to the assemble of MNP and MRET ON phenomenon between MNP assembly and Gd3+ . Once MPD-1 accumulates at the bacterially infected site, P1 included in MPD-1 is cleaved explicitly by MMP-2, which triggers the T2 contrast agent of MPD-1 to disassemble into the monomer of MNP, leading the recovery of T1 -weighted signal. Simultaneously, Gd3+ detaches from MNP, further enhancing the T1 -weighted signal due to MRET OFF. The sensitive MRI of Staphylococcus aureus (low to 104 CFU) at the myositis site and accurate differentiation between sterile inflammation and bacterial infection based on the proposed MPD-1 probe suggests that this novel probe would be a promising candidate for efficiently detecting bacterial infection in vivo.

Ultrasonography performed by an infectiologist in hip and knee prosthetic joint and native joint infections

INTRODUCTION

Clinical ultrasonography (US) by infectiologists has only recently been developing, and as now there is little literature on the subject. Our study focuses on the conditions and diagnostic performance of clinical ultrasound imaging by infectiologists in cases of hip and knee prosthetic and native joint infection.

METHODS

A retrospective study carried out between June 1^st 2019 and March 31^st 2021 in the University Hospital of Bordeaux, South-Western France. We measured US sensitivity (Se), specificity (Sp), positive predictive value (PPV) and negative predictive value (NPV), combined or not with the analysis of articular fluid, compared to the MusculoSketetal Infection Society (MSIS) score in prosthetic joints, or to expert diagnosis in native joints.

RESULTS

Fifty-four patients underwent US by an infectiologist in an infectious disease ward, including 11 (20.4%) for native joint and 43 (79.6%) for prosthetic joint. Joint effusion and/or periarticular collection were highlighted in 47 (87%) patients, and US led to 44 punctures. In all patients (n=54), Se, Sp, PPV and NPV of US alone were 91%, 19%, 64% and 57%, respectively. When US was combined with fluid analysis, Se, Sp, PPV, NPV were 68%, 100%, 100%, 64% in all patients (n=54), 86%, 100%, 100%, 60% in acute arthritis (n=17) and 50%, 100%, 100% and 65% respectively in non-acute arthritis (n=37).

CONCLUSION

These results suggest that US by infectiologists effectively diagnoses osteoarticular infections (OAIs). This approach has many applications in infectiology routines. Consequently, it would be interesting to define the contents of a first level of infectiologist competence in US clinical practice.

Bacteria-Targeted MRI Probe-Based Imaging Bacterial Infection and Monitoring Antimicrobial Therapy In Vivo

Despite the significant advances of imaging techniques nowadays, accurate diagnosis of bacterial infections and real-time monitoring the efficacy of antibiotic therapy in vivo still remain huge challenges. Herein, a self-assembling peptide (FFYEGK) and vancomycin (Van) antibiotic molecule co-modified gadolinium (Gd) MRI nanoaggregate probe (GFV) for detecting Staphylococcus aureus (S. aureus) infection in vivo and monitoring the treatment of S. aureus-infected myositis by using daptomycin (Dap) antibiotic as model are designed and fabricated. The as-prepared GFV probe bears Van molecules, making itself good bacteria-specific targeting, and the peptide in the probe can enhance the longitudinal relaxivity rate (r₁ ) after self-assembly due to the π-π stacking. The study showed that, based on the GFV probe, bacterial infections and sterile inflammation can be discriminated, and as few as 10⁵ cfu S. aureus can be detected in vivo with high specificity and accurately. Moreover, the T₁ signal of GFV probe at the S. aureus-infected site in mice correlates with the increasing time of Dap treating, indicating the possibility of monitoring the efficacy of antibacterial agents for infected mice based on the as proposed GFV probe. This study shows the potential of GFV probe for diagnosis, evaluation, and prognosis of infectious diseases in clinics.

Ultrasound-responsive polymer-based drug delivery systems

Ultrasound-responsive polymeric materials have received a tremendous amount of attention from scientists for several decades. Compared to other stimuli-responsive materials (such as UV-, thermal-, and pH-responsive materials), these smart materials are more applicable since they allow more efficient drug delivery and targeted treatment by fairly non-invasive means. This review describes the recent advances of such ultrasound-responsive polymer-based drug delivery systems and illustrates various applications. More specifically, the mechanism of ultrasound-induced drug delivery, typical formulations, and biomedical applications (tumor therapy, disruption of blood-brain barrier, fighting infectious diseases, transdermal drug delivery, and enhanced thrombolysis) are summarized. Finally, a perspective on the future research directions for the development of ultrasound-responsive polymeric materials to facilitate a clinical translation is given.

Emerging applications of clinical ultrasonography

In this work, we introduce the numerous emerging areas and frontiers in the use of point-of-care ultrasonography. Of these, we review the following three: 1) the use of clinical ultrasonography in infectious and tropical diseases (we address its usefulness in the diagnosis and follow-up of the main syndromes, in tropical diseases, and in areas with scarce resources); 2) the usefulness of clinical ultrasonography in the assessment of response to volume infusion in severely ill patients (we review basic concepts and the main static and dynamic variables used for this evaluation); and 3) the use of clinical ultrasonography in the assessment of muscle mass in elderly patients with primary sarcopenia (we review the main muscles and measurements used for it).

Emerging applications of clinical ultrasonography

In this work, we introduce the numerous emerging areas and frontiers in the use of point-of-care ultrasonography. Of these, we review the following three: 1) the use of clinical ultrasonography in infectious and tropical diseases (we address its usefulness in the diagnosis and follow-up of the main syndromes, in tropical diseases, and in areas with scarce resources); 2) the usefulness of clinical ultrasonography in the assessment of response to volume infusion in severely ill patients (we review basic concepts and the main static and dynamic variables used for this evaluation); and 3) the use of clinical ultrasonography in the assessment of muscle mass in elderly patients with primary sarcopenia (we review the main muscles and measurements used for it).

Advances in point-of-care diagnostic devices in cancers

The early diagnosis and monitoring of the progress of cancers are limited due to the lack of adequate screening tools.

Point-of-Care Ultrasound Assessment of Tropical Infectious Diseases--A Review of Applications and Perspectives

The development of good quality and affordable ultrasound machines has led to the establishment and implementation of numerous point-of-care ultrasound (POCUS) protocols in various medical disciplines. POCUS for major infectious diseases endemic in tropical regions has received less attention, despite its likely even more pronounced benefit for populations with limited access to imaging infrastructure. Focused assessment with sonography for HIV-associated TB (FASH) and echinococcosis (FASE) are the only two POCUS protocols for tropical infectious diseases, which have been formally investigated and which have been implemented in routine patient care today. This review collates the available evidence for FASH and FASE, and discusses sonographic experiences reported for urinary and intestinal schistosomiasis, lymphatic filariasis, viral hemorrhagic fevers, amebic liver abscess, and visceral leishmaniasis. Potential POCUS protocols are suggested and technical as well as training aspects in the context of resource-limited settings are reviewed. Using the focused approach for tropical infectious diseases will make ultrasound diagnosis available to patients who would otherwise have very limited or no access to medical imaging.