Sonication assisted microbiological diagnosis of implant-related infection caused by Prevotella disiens and Staphylococcus epidermidis in a patient with cranioplasty

Multi-omics analysis reveals the interplay between pulmonary microbiome and host in immunocompromised patients with sepsis-induced acute lung injury

The mechanisms behind the high inflammatory state and immunocompromise in severe sepsis remain unclear. While microbiota's role in immune regulation is known, the impact of pulmonary microbiota on sepsis progression is not fully understood. This study aims to investigate pulmonary microbial characteristics in septic patients and their relationship with host immune-related genes and clinical features. Fifty-four sepsis patients were divided into the immunocompromised host (ICH) group (n = 18) and the control group (n = 36). Bronchoalveolar lavage fluid (BALF) was analyzed using metagenomic next-generation sequencing (mNGS) to assess the pulmonary microbiome, and transcriptomic sequencing evaluated host gene expression. The pulmonary microbiota network in the ICH group showed notable alterations. Symbiotic bacteria like Streptococcus salivarius and Streptococcus oralis were key taxa in the control group. In contrast, opportunistic pathogens such as Campylobacter concisus and Prevotella melaninogenica, typically linked to infections in various body sites, dominated in the ICH group. Transcriptomic analysis revealed differential genes between the two groups. The downregulated differential genes in the ICH group were primarily enriched in pathways related to T-cell activation and the Type I interferon signaling pathway, both crucial for the immune system. Further correlation analysis identified significant associations between certain microbes and host genes, as well as clinical indicators, particularly with species like Campylobacter concisus, Streptococcus salivarius, Streptococcus oralis, and several species of Veillonella. These findings suggest that alterations in the pulmonary microbiome, especially the presence of opportunistic pathogens, may contribute to immune dysregulation in immunocompromised septic patients, warranting further research to explore causal relationships.

IMPORTANCE

Recent research has substantiated the significant role of microbiota in immune regulation, which could influence high inflammatory state and immunocompromise in patients with severe sepsis, as well as provide new opportunities for acute lung injury induced by sepsis diagnosis and treatment. Our study identified some potential critical microbes (Campylobacter concisus and several species of Veillonella), which were correlated with immune-related genes and might be the novel target to regulate immunotherapy in sepsis.

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

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.

Prevotella diversity, niches and interactions with the human host

The genus Prevotella includes more than 50 characterized species that occur in varied natural habitats, although most Prevotella spp. are associated with humans. In the human microbiome, Prevotella spp. are highly abundant in various body sites, where they are key players in the balance between health and disease. Host factors related to diet, lifestyle and geography are fundamental in affecting the diversity and prevalence of Prevotella species and strains in the human microbiome. These factors, along with the ecological relationship of Prevotella with other members of the microbiome, likely determine the extent of the contribution of Prevotella to human metabolism and health. Here we review the diversity, prevalence and potential connection of Prevotella spp. in the human host, highlighting how genomic methods and analysis have improved and should further help in framing their ecological role. We also provide suggestions for future research to improve understanding of the possible functions of Prevotella spp. and the effects of the Western lifestyle and diet on the host-Prevotella symbiotic relationship in the context of maintaining human health.

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

OBJECTIVE

Postoperative infections are one of the most devastating complications in neurosurgery, and their results are even more disastrous when biocompatible implants are involved. As the application of these implants increases, the need for a sensitive and efficient method to detect pathogens becomes imperative. The application of sonication appears to be a viable option.

METHODS

A systematic review and meta-analysis of the available literature was conducted, looking for studies reporting findings from the application of sonication following neurosurgical operations. To be included, an article needed to contain information about the material that was subjected to sonication, indication of other culture methods that were applied, and information about the isolated pathogens.

RESULTS

Six studies comprising 437 patients were included in the meta-analysis. Potential superiority of sonication over conventional microbiologic methods was found in the detection of gram-positive bacteria and in particular of coagulase-negative Staphylococcus species. A sensitivity of 0.87 and a specificity of 0.57 were calculated.

CONCLUSIONS

Regardless of the potential of sonication, it is still not a panacea. Additional studies are expected to provide significant insight into the indications and limitations of this technique.

The nasal and oropharyngeal microbiomes of healthy livestock workers

Little information exists on the microbiomes of livestock workers. A cross-sectional, epidemiological study was conducted enrolling 59 participants (26 of which had livestock contact) in Iowa. Participants were enrolled in one of four ways: from an existing prospective cohort study (n = 38), from the Iowa Department of Natural Resources Animal Feeding Operations database (n = 17), through Iowa county fairs (n = 3), and through snowball sampling (n = 1). We collected swabs from the nares and oropharynx of each participant to assess the microbiome via 16s rRNA sequencing. We observed livestock workers to have greater diversity in their microbiomes compared to those with no livestock contact. In the nares, there were 27 operational taxonomic units found to be different between livestock workers and non-livestock workers with the greatest difference seen with Streptococcus and Proteobacteria. In the oropharynx, livestock workers with swine exposure were more likely to carry several pathogenic organisms. The results of this study are the first to characterize the livestock worker nasal and oropharyngeal microbiomes.

Nanosilver/poly (dl-lactic-co-glycolic acid) on titanium implant surfaces for the enhancement of antibacterial properties and osteoinductivity

Background

Despite titanium (Ti) implants have been commonly used in the medical device field due to their superior biocompatibility, implant-associated bacterial infection remains a major clinical complication. Nanosilver, an effective antibacterial agent against a wide spectrum of bacterial strains, with a low-resistance potential, has attracted much interest too. Incorporation of nanosilver on Ti implants may be a promising approach to prevent biofilm formation.

Purpose

The objective of the study was to investigate the antibacterial effects and osteoinductive properties of nanosilver/poly (dl-lactic-co-glycolic acid)-coated titanium (NSPTi).

Methods

Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and the Gram-negative opportunistic pathogen Pseudomonas aeruginosa (PAO-1) were used to evaluate the antibacterial activity of NSPTi implants through the analysis of bacterial colonization in vitro and in vivo. Furthermore, we examined the osteoinductive potential of NSPTi implants by investigating the proliferation and differentiation of MC3T3-E1 preosteoblast cells. In vivo, the osteoinductive properties of NSPTi implants were assessed by radiographic evaluation, H&E staining, and Masson’s trichrome staining.

Results

In vitro, bacterial adhesion to the 2% NSPTi was significantly inhibited and <1% of adhered bacteria survived after 24 hours. In vitro, the average colony-forming units (CFU)/g ratios in the 2% NSPTi with 10³ CFU MRSA and PAO-1 were 1.50±0.68 and 1.75±0.6, respectively. In the uncoated Ti groups, the ratios were 1.03±0.82×10³ and 0.94±0.49×10³, respectively. These results demonstrated that NSPTi implants had prominent antibacterial properties. Proliferation of MC3T3-E1 cells on the 2% NSPTi sample was 1.51, 1.78, and 2.22 times that on the uncoated Ti control after 3, 5, and 7 days’ incubation, respectively. Furthermore, NSPTi implants promoted the maturation and differentiation of MC3T3-E1 cells. In vivo, NSPTi accelerated the formation of new bone while suppressing bacterial survival.

Conclusion

NSPTi implants have simultaneous antibacterial and osteoinductive activities and therefore have the potential in clinical applications.

Diagnostic Approach to Health Care- and Device-Associated Central Nervous System Infections

Health care- and device-associated central nervous system (CNS) infections have a distinct epidemiology, pathophysiology, and microbiology that require a unique diagnostic approach. Most clinical signs, symptoms, and tests used to diagnose community-acquired CNS infections are insensitive and nonspecific in neurosurgical patients due to postsurgical changes, invasive devices, prior antimicrobial exposure, and underlying CNS disease. The lack of a standardized definition of infection or diagnostic pathway has added to this challenge. In this review, we summarize the epidemiology, microbiology, and clinical presentation of these infections, discuss the issues with existing microbiologic tests, and give an overview of the current diagnostic approach.

Management of infections associated with neurosurgical implanted devices

INTRODUCTION

Neurosurgical devices are increasingly used. With it, neurosurgical device-related infections gain relevance. As biofilms are involved in implant-associated infections the diagnosis and treatment is challenging and requires specific anti-biofilm concepts and management algorithms. Areas covered: The literature concerning the management of neurosurgical device-associated infections is scarce and heterogeneous treatment concepts are discussed, but no standardized diagnostic and treatment procedures exist. Therefore, we emphasize extrapolating management strategies predominantly from orthopedic device-associated infections, where the concept is better established and clinically validated. This review covers infections associated with craniotomy fixation devices, cranioplasties, external ventricular and lumbar drainages, internal shunts and neurostimulators. Expert commentary: Sonication of the removed implants significantly improves microbiological diagnosis. A combined surgical and antimicrobial management is crucial for successful treatment: appropriate surgical intervention is combined with prolonged anti-biofilm therapy of usually 12 weeks. In selected patients, new treatment algorithms enable cure of neurosurgical device-associated infections without implant removal or with a one-stage implant exchange, considerably improving the quality of patient lives.