Use of Focused Ultrasound (Sonication) for the Diagnosis of Infections in Neurosurgical Operations: A Systematic Review and Meta-Analysis

A meta-analysis on the role of sonication in the diagnosis of cardiac implantable electronic device-related infections

Introduction

One of the biggest obstacles in diagnosing Implant-Associated Infections is the lack of infection criteria and standardized diagnostic methods. These infections present a wide range of symptoms, and their diagnosis can be hampered by the formation of microbial biofilms on the surface of implants. This study aimed to provide insight into the performance of sonication in the diagnosis of infections associated with Cardiac Implantable Electronic Devices, to help define a consensus on the algorithm for the microbial diagnosis of these infections.

Methods

We carried out a systematic review with meta-analysis. The PRISMA methodology guidelines were followed, and an advanced search was carried out in PubMed and Web of Science, which enabled 8 articles to be included in the review, in which a meta-analysis was also carried out. QUADAS-2 was used to assess the risk of bias and effect measures were calculated to assess publication bias.

Results

The overall sensitivity of the method was 0.823 (95% CI: 0.682-0.910) and the specificity was 0.632 (95% CI: 0.506-0.743).

Discussion

These results suggest that sonication may offer advantages in diagnosing these infections. However, it is essential to approach these findings carefully and take into account the recommendations provided in the EHRA 2019 guidelines. This study highlights the importance of more effective diagnostic approaches for implantable medical device-associated infections to improve the quality of treatment and minimize the risks associated with these challenging medical conditions.

Current Perspectives on the Diagnosis and Management of Healthcare-Associated Ventriculitis and Meningitis

Ventriculitis or post-neurosurgical meningitis or healthcare-associated ventriculitis and meningitis (VM) is a severe infection that complicates central nervous system operations or is related to the use of neurosurgical devices or drainage catheters. It can further deteriorate patients who have already presented significant neurologic injury and is associated with high morbidity, mortality, and poor functional outcome. VM can be difficult to distinguish from aseptic meningitis, inflammation that follows hemorrhagic strokes and neurosurgical operations. The associated microorganisms can be either skin flora or nosocomial pathogens, most commonly, Gram-negative bacteria. Classical microbiology can fail to isolate the culprit pathogen. Novel cerebrospinal fluid (CSF) biomarkers and molecular microbiology can fill the diagnostic gap and expedite pathogen identification and treatment. The pathogens may demonstrate significant resistant patterns and their antibiotic treatment can be difficult, as many important drug classes, including the beta-lactams and the glycopeptides, hardly penetrate to the CSF, and do not achieve therapeutic levels at the site of the infection. Treatment modifications, such as higher daily dose and prolonged or continuous administration, might increase antibiotic levels in the site of infection and facilitate pathogens clearance. However, in the case of therapeutic failure or infection due to difficult-to-treat bacteria, the direct antibiotic instillation into the CSF, in addition to the intravenous antibiotic delivery, may help in the resolution of infection. However, intraventricular antibiotic therapy may result in aseptic meningitis and seizures, concerning the administration of aminoglycosides, polymyxins, and vancomycin. Meanwhile, bacteria form biofilms on the catheter or the device that should routinely be removed. Novel neurosurgical treatment modalities comprise endoscopic evacuation of debris and irrigation of the ventricles. VM prevention includes perioperative antibiotics, antimicrobial impregnated catheters, and the implementation of standardized protocols, regarding catheter insertion and manipulation.

Challenges in the Microbiological Diagnosis of Implant-Associated Infections: A Summary of the Current Knowledge

Implant-associated infections are characterized by microbial biofilm formation on implant surface, which renders the microbiological diagnosis challenging and requires, in the majority of cases, a complete device removal along with a prolonged antimicrobial therapy. Traditional cultures have shown unsatisfactory sensitivity and a significant advance in the field has been represented by both the application of the sonication technique for the detachment of live bacteria from biofilm and the implementation of metabolic and molecular assays. However, despite the recent progresses in the microbiological diagnosis have considerably reduced the rate of culture-negative infections, still their reported incidence is not negligible. Overall, several culture- and non-culture based methods have been developed for diagnosis optimization, which mostly relies on pre-operative and intra-operative (i.e., removed implants and surrounding tissues) samples. This review outlines the principal culture- and non-culture based methods for the diagnosis of the causative agents of implant-associated infections and gives an overview on their application in the clinical practice. Furthermore, advantages and disadvantages of each method are described.