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.

Lower Rates of Reoperation Following Partial or Complete Revision Arthroplasty Compared to Debridement, Antibiotics, and Implant Retention for Early Postoperative and Acute Hematogenous Periprosthetic Hip Infection.

BACKGROUND: This study aimed to: 1) compare treatment outcomes between debridement, antibiotics, and implant retention (DAIR) and partial or complete revision arthroplasty (RA) for early postoperative and acute hematogenous total hip arthroplasty periprosthetic joint infection (PJI) and 2) identify factors associated with treatment outcome. METHODS: The study consisted of a retrospective cohort of patients who underwent surgery for PJI between 2004 and 2021. There were 76 patients (74.5%) who underwent DAIR and 26 patients (25.5%) who underwent RA. Treatment success was defined as treatment eradication at a minimum of a 2-year follow up. Bivariate regression analysis was used to assess the effect of different factors on treatment outcomes. Kaplan-Meier survivorship was performed to compare survivorship between cohorts. RESULTS: At a mean follow-up of 8.2 years (range, 2.2 to 16.4), significantly more DAIR failed treatment (DAIR, 50 [65.8%]; 10 [38.5%]; P = .015). The 8-year Kaplan-Meier survivorship was 35.1% [95% confidence interval (CI), 24.3 to 45.9] for patients treated with DAIR and 61.5% [95% CI, 42.9 to 80.1] for those treated with RA (log rank = 0.039). Bivariate regression analysis showed performing a RA was associated with a higher likelihood of treatment success (odds ratio 4.499, 95% CI 1.600 to 12.647, P = .004), whereas a higher body mass index was associated with treatment failure (odds ratio 0.934, 95% CI 0.878 to 0.994, P = .032). CONCLUSIONS: To reduce the rate of recalcitrant infection following early postoperative or acute hematogenous total hip arthroplasty PJI, RA may be of benefit over DAIR. This is especially relevant in the early postoperative period, when components can be readily exchanged.

Is the routine use of local antibiotics in the management of periprosthetic joint infections justified?

Periprosthetic joint infection (PJI) following total hip and total knee arthroplasty continues to be a leading cause of re-operation and revision arthroplasty. Not only is the treatment of PJI notoriously challenging, but success rates are variable. Regardless of the surgical strategy used, successful management of PJI requires a comprehensive surgical debridement focused at eradicating the underlying biofilm followed by appropriate antimicrobial therapy. Although systemic antimicrobial delivery continues to be a cornerstone in the treatment of PJI, many surgeons have started using local antibiotics to deliver higher concentrations of antibiotics directly into the vulnerable joint and adjacent soft tissues, which often have compromised vascularity. Available evidence on the use of topical powder, bone cement, and calcium sulphate carriers for local delivery of antibiotics during the initial treatment of PJI is limited to studies that are extremely heterogeneous. There is currently no level-1 evidence to support routinely using these products. Further, appropriately powered, prospective studies are needed to quantify the safety and efficacy of antibiotic-located calcium-sulphate carriers to justify their added costs. These products should not encourage surgeons to deviate from best practice guidelines, such as those recommended during the International Consensus Meeting on Musculoskeletal Infections.

Clinical Use of a 16S Ribosomal RNA Gene-Based Sanger and/or Next Generation Sequencing Assay to Test Preoperative Synovial Fluid for Periprosthetic Joint Infection Diagnosis.

Preoperative pathogen identification in patients with periprosthetic joint infection (PJI) is typically limited to synovial fluid culture. Whether sequencing-based approaches are of potential use in identification of pathogens in PJI, and if so which approach is ideal, is incompletely defined. The objective of the study was to analyze the accuracy of a 16S rRNA (rRNA) gene-based PCR followed by Sanger sequencing and/or targeted metagenomic sequencing approach (tMGS) performed on synovial fluid for PJI diagnosis. A retrospective study was conducted, analyzing synovial fluids tested between August 2020 and May 2021 at a single center. Subjects with hip, knee, shoulder, and elbow arthroplasties who had synovial fluid aspirated and clinically subjected to sequence-based testing and conventional culture were studied. A total of 154 subjects were included in the study; 118 had noninfectious arthroplasty failure (NIAF), while 36 had PJI. Clinical sensitivity and specificity for diagnosis of PJI were 69% and 100%, respectively, for the sequencing-based approach and 72% and 100%, respectively, for conventional culture (P = 0.74). The combination of both tests was more sensitive (83%) than culture alone (P = 0.04). Results of sequencing-based testing led to changes in treatment in four of 36 (11%) PJI subjects. Microbial identification was achieved using Sanger and next generation sequencing in 19 and 6 subjects, respectively. When combined with culture, the described 16S rRNA gene sequencing-based approach increased sensitivity compared to culture alone, suggesting its potential use in the diagnosis of PJI when synovial fluid culture is negative. IMPORTANCE Periprosthetic joint infection (PJI) is a dreadful complication of joint replacement. Noninvasive identification of infectious pathogens has been traditionnally limited to culture-based testing of synovial fluid which has poor sensitivity. Sanger and Next-generation sequencing (NGS) may be used for synovial fluid testing in PJI, but experience in routine practice is sparse. We used a targeted metagenomic sequencing approach for routine testing of synovial fluid involving NGS when Sanger sequencing had failed or was likely to fail. The objective of this study was to analyze the approach's performance for diagnosis of PJI in comparison to culture for testing synovial fluid. Overall, the sequencing-based approach was not superior to culture for diagnosis of PJI, but yielded positive results in some culture-negative samples.

Robinsoniella peoriensis: An emerging pathogen and rare cause of wound infection in children.

BACKGROUND: Robinsoniella peoriensis is an anaerobic gram-positive bacilli first isolated from swine manure in 2003 but has since been associated with human infections. METHODS: We describe a pediatric case of R. peoriensis infection following a below-knee amputation for a limb injury and its treatment. Methods of identifying R. peoriensis and reported in vitro antimicrobial minimum inhibitory concentrations from the literature are reviewed. RESULTS: R. peoriensis is readily identifiable via 16S rRNA gene sequencing and Matrix-Assisted Laser Desorption Ionization-Time of Flight. There is variability in the antibiotic susceptibility profiles reported in the literature, but antibiotics with low in vitro minimum inhibitor concentrations against R. peoriensis include beta-lactam/beta-lactamase inhibitors, carbapenems, vancomycin, and metronidazole. CONCLUSION: This is the first reported case of R. peoriensis infection following a traumatic injury in Canada to our knowledge and highlights the importance of recognizing this organism and other anaerobes in settings where wounds are grossly contaminated with soil.

HISTORIQUE: Le Robinsoniella peoriensis est un bacille anaérobie à Gram positif d'abord isolé en 2003 dans le lisier de porc, mais qui a été associé à des infections humaines depuis. MÉTHODOLOGIE: Les auteurs décrivent un cas pédiatrique d'infection à R. peoriensis après une amputation au-dessous du genou à cause de la lésion d'un membre et de son traitement. Les chercheurs ont examiné les méthodes pour identifier le R. peoriensis et les concentrations minimales inhibitrices antimicrobiennes in vitro tirées des publications. RÉSULTATS: Le R. peoriensis est facile à identifier au moyen du séquençage du gène d'ARNr 16S et du spectromètre de masse à temps de vol pour la désorption-ionisation laser assistée par matrice. La description des profils de susceptibilité des antibiotiques est variable selon les publications, mais les antibiotiques aux concentrations minimales inhibitrices contre le R. peoriensis sont les bêta-lactamines et les inhibiteurs de bêta-lactamase, les carbapénems, la vancomycine et le métronidazole. CONCLUSION: À la connaissance des auteurs, il s'agit du premier cas déclaré d'infection à R. peoriensis après une lésion traumatique au Canada, ce qui fait ressortir l'importance de tenir compte de cet organisme et d'autres anaérobies lorsque les plaies sont grandement contaminées par de la terre.

Comparison of the BioFire Joint Infection Panel to 16S Ribosomal RNA Gene-Based Targeted Metagenomic Sequencing for Testing Synovial Fluid from Patients with Knee Arthroplasty Failure.

The diagnosis of periprosthetic joint infection (PJI) is challenging, often requiring multiple clinical specimens and diagnostic techniques, some with prolonged result turnaround times. Here, the diagnostic performance of the Investigational Use Only (IUO) BioFire Joint Infection (JI) Panel was compared to 16S rRNA gene-based targeted metagenomic sequencing (tMGS) applied to synovial fluid for PJI diagnosis. Sixty synovial fluid samples from knee arthroplasty failure archived at -80°C were tested. Infectious Diseases Society of America (IDSA) diagnostic criteria were used to classify PJI. For culture-positive PJI with pathogens targeted by the JI panel, JI panel sensitivity was 91% (21/23; 95% confidence interval [CI], 73 to 98%), and tMGS sensitivity was 96% (23/24; 95% CI, 80 to 99%) (P = 0.56). Overall sensitivities of the JI panel and tMGS for PJI diagnosis were 56% (24/43; 95% CI, 41 to 70%) and 93% (41/44; 95% CI, 82 to 98%), respectively (P < 0.001). JI panel and tMGS overall specificities were 100% (16/16; 95% CI, 81 to 100%) and 94% (15/16; 95% CI, 72 to 99%), respectively. While the clinical sensitivity of the JI panel was excellent for on-panel microorganisms, overall sensitivity for PJI diagnosis was low due to the absence of Staphylococcus epidermidis, a common causative pathogen of PJI, on the panel. A PJI diagnostic algorithm for the use of both molecular tests is proposed.

Management of Periprosthetic Joint Infections After Hemiarthroplasty of the Hip: A Critical Analysis Review.

➢: Periprosthetic joint infection (PJI) following hip hemiarthroplasty (HA) is a devastating complication, incurring immense health-care costs associated with its treatment and placing considerable burden on patients and their families. These patients often require multiple surgical procedures, extended hospitalization, and prolonged antimicrobial therapy. ➢: Notable risk factors include older age, higher American Society of Anesthesiologists (ASA) score, inadequate antibiotic prophylaxis, non-antibiotic-loaded cementation of the femoral implant, longer duration of the surgical procedure, and postoperative drainage and hematoma. ➢: Although the most frequent infecting organisms are gram-positive cocci such as Staphylococcus aureus, there is a higher proportion of patients with gram-negative and polymicrobial infections after hip HA compared with patients who underwent total hip arthroplasty. ➢: Several surgical strategies exist. Regardless of the preferred surgical treatment, successful management of these infections requires a comprehensive surgical debridement focused on eradicating the biofilm followed by appropriate antibiotic therapy. ➢: A multidisciplinary approach led by surgeons familiar with PJI treatment and infectious disease specialists is recommended for all cases of PJI after hip HA to increase the likelihood of treatment success.

Experiences of Bereaved Family Members Receiving Commemorative Paintings: A Qualitative Study.

Importance: Although family members of patients who die in the intensive care unit commonly experience long-term psychological distress, end-of-life bereavement support programs for such relatives are uncommon. Whether art influences the grief experience of families is largely unexplored. Objective: To explore the influence of personalized paintings created to honor deceased critically ill patients on family members' bereavement experience. Design, Setting, and Participants: A qualitative descriptive analysis was conducted of semistructured interviews of grieving relatives who received a painting after the death of their loved one. The deceased patients were from a 21-bed medical-surgical intensive care unit. Eleven families were invited to receive a painting, of whom 1 family declined. A total of 22 family members of 10 patients who died in the intensive care unit were interviewed in the study between July 11, 2017, and May 19, 2019. Interventions: Patients were enrolled in an end-of-life care program that elicits and implements wishes of patients and their families to bring peace during the dying process. Selected families of 10 decedents were invited to receive a painting to honor their loved one 1 to 10 months after the patient's death. Using details about the patient's life story, the artist created individualized paintings to commemorate each patient. Main Outcomes and Measures: The experiences of family members receiving a personalized painting and its reported influence on their grieving experience. Results: The family members of 10 decedents (mean [SD] age, 60 [14] years; 5 women [50%]; 8 White patients [80%]) were interviewed. The central theme of art to facilitate healing was illustrated through the following domains: the cocreation process, painting narratives, postmortem connections, and legacy. The process of cocreating the paintings with the artist and family members involved reminiscing, storytelling, and creativity. Family members emphasized the role of art to facilitate healing, exemplified through connections with images portrayed that deeply resonated with memories of their loved one. Participants indicated that the paintings validated that the patient was remembered, helped families feel less alone during a time of grief, honored the loved one's life, and enhanced connections between family members and clinicians. Conclusions and Relevance: This qualitative study's findings suggest that the creation of personalized paintings commemorating the lives of patients may help foster legacy and postmortem connections with clinicians and may help family members in their healing process.

The comprehensive antibiotic resistance database.

The field of antibiotic drug discovery and the monitoring of new antibiotic resistance elements have yet to fully exploit the power of the genome revolution. Despite the fact that the first genomes sequenced of free living organisms were those of bacteria, there have been few specialized bioinformatic tools developed to mine the growing amount of genomic data associated with pathogens. In particular, there are few tools to study the genetics and genomics of antibiotic resistance and how it impacts bacterial populations, ecology, and the clinic. We have initiated development of such tools in the form of the Comprehensive Antibiotic Research Database (CARD; http://arpcard.mcmaster.ca). The CARD integrates disparate molecular and sequence data, provides a unique organizing principle in the form of the Antibiotic Resistance Ontology (ARO), and can quickly identify putative antibiotic resistance genes in new unannotated genome sequences. This unique platform provides an informatic tool that bridges antibiotic resistance concerns in health care, agriculture, and the environment.

Determining the mode of action of bioactive compounds.

Matching bioactive molecules with molecular targets is key to understanding their modes of action (MOA). Moving beyond the mere discovery of drugs, investigators are now just beginning to integrate both biochemical and chemical-genetic approaches for MOA studies. Beginning with simple screens for changes in cell phenotype upon drug treatment, drug bioactivity has been traditionally explored with affinity chromatography, radiolabeling, and cell-based affinity tagging procedures. However, such approaches can present an oversimplified view of MOA, especially in light of the recent realization of the extent of polypharmacology and the unexpected complexity of drug-target interactions. With the advent of more sophisticated tools for genetic manipulation, a flood of powerful techniques has been used to create characteristic drug MOA 'fingerprints'. In particular, whole genome expression profiling and deletion and overexpression libraries have greatly enhanced our understanding of bioactive compounds in vivo. Here we highlight challenges and advances in studying bioactive compound-target interactions.

Bioactivity and the first transmission electron microscopy immunogold studies of short de novo-designed antimicrobial peptides.

In light of the era of microbial drug resistance, the current study aimed to better understand the relationships between sequence, higher-order structure, and mechanism of action for five designed peptides against multidrug-resistant (MDR) pathogens. All peptides studied were 15 residues long, were polycationic, adopted alpha-helical structures within hydrophobic environments (excluding the d-amino acid-substituted peptide MA-d), and contained N-terminal glycine residues, a novel antimicrobial peptide (AMP) design principle. Increasing hydrophobicity enhanced MICs (≤500 µg/ml to ≤7.4 µg/ml) without significantly increasing hemolytic activity (18% maximum hemolysis at 3,400 µg/ml). To the best of our knowledge, this is the first study to have successfully adapted and used a transmission electron microscopy (TEM) immunogold method to investigate the mechanism of action of short (∼15 residues long) AMPs within bacteria. We propose a "floodgate" mechanism to possibly explain membrane deformation and the relative absence of membrane-associated peptides 10 h into incubation.