Increased Resistance of Skin Flora to Antimicrobial Prophylaxis in Patients Undergoing Hip Revision Arthroplasty

Wound Microbiota and Its Impact on Wound Healing

Wound healing is a complex process influenced by age, systemic conditions, and local factors. The wound microbiota's crucial role in this process is gaining recognition. This concise review outlines wound microbiota impacts on healing, emphasizing distinct phases like hemostasis, inflammation, and cell proliferation. Inflammatory responses, orchestrated by growth factors and cytokines, recruit neutrophils and monocytes to eliminate pathogens and debris. Notably, microbiota alterations relate to changes in wound healing dynamics. Commensal bacteria influence immune responses, keratinocyte growth, and blood vessel development. For instance, Staphylococcus epidermidis aids keratinocyte progression, while Staphylococcus aureus colonization impedes healing. Other bacteria like Group A Streptococcus spp. And Pseudomonas affect wound healing as well. Clinical applications of microbiota-based wound care are promising, with probiotics and specific bacteria like Acinetobacter baumannii aiding tissue repair through molecule secretion. Understanding microbiota influence on wound healing offers therapeutic avenues. Tailored approaches, including probiotics, prebiotics, and antibiotics, can manipulate the microbiota to enhance immune modulation, tissue repair, and inflammation control. Despite progress, critical questions linger. Determining the ideal microbiota composition for optimal wound healing, elucidating precise influence mechanisms, devising effective manipulation strategies, and comprehending the intricate interplay between the microbiota, host, and other factors require further exploration.

Engineering 3D-Printed Advanced Healthcare Materials for Periprosthetic Joint Infections

The use of additive manufacturing or 3D printing in biomedicine has experienced fast growth in the last few years, becoming a promising tool in pharmaceutical development and manufacturing, especially in parenteral formulations and implantable drug delivery systems (IDDSs). Periprosthetic joint infections (PJIs) are a common complication in arthroplasties, with a prevalence of over 4%. There is still no treatment that fully covers the need for preventing and treating biofilm formation. However, 3D printing plays a major role in the development of novel therapies for PJIs. This review will provide a deep understanding of the different approaches based on 3D-printing techniques for the current management and prophylaxis of PJIs. The two main strategies are focused on IDDSs that are loaded or coated with antimicrobials, commonly in combination with bone regeneration agents and 3D-printed orthopedic implants with modified surfaces and antimicrobial properties. The wide variety of printing methods and materials have allowed for the manufacture of IDDSs that are perfectly adjusted to patients' physiognomy, with different drug release profiles, geometries, and inner and outer architectures, and are fully individualized, targeting specific pathogens. Although these novel treatments are demonstrating promising results, in vivo studies and clinical trials are required for their translation from the bench to the market.

Impacts of Mechanical Stiffness of Bacteriophage-Loaded Hydrogels on Their Antibacterial Activity

The elaboration of efficient hydrogel-based materials with antimicrobial properties requires a refined control of defining their physicochemical features, which includes mechanical stiffness, so as to properly mediate their antibacterial activity. In this work, we design hydrogels consisting of polyelectrolyte multilayer films for the loading of T4 and φX174 bacteria-killing viruses, also called bacteriophages. We investigate the antiadhesion and bactericidal performances of this biomaterial against Escherichia coli, with a specific focus on the effects of chemical cross-linking of the hydrogel matrix, which, in turn, mediates the hydrogel stiffness. Depending on the latter and on phage replication features, it is found that the hydrogels loaded with the bacteria-killing viruses make both contact killing (targeted bacteria are those adhered at the hydrogel surface) and release killing (planktonic bacteria are the targets) possible with ca. 20-80% efficiency after only 4 h of incubation at 25 °C as compared to cases where hydrogels are free of viruses. We further demonstrate the lack of dependence of virus diffusion within the hydrogel and of the maximal viral storage capacity on the hydrogel mechanical properties. In addition to the evidenced bacteriolytic activity of the phages loaded in the hydrogels, the antimicrobial property of the phage-loaded materials is shown to be partly controlled by the chemistry of the hydrogel skeleton and, more specifically, by the mobility of the peripheral free polycationic components, known for their ability to weaken and permeabilize membranes of bacteria, the latter then becoming "easier" targets for the viruses.

Methicillin-Resistant Staphylococcus epidermidis Lineages in the Nasal and Skin Microbiota of Patients Planned for Arthroplasty Surgery

Staphylococcus epidermidis, ubiquitous in the human nasal and skin microbiota, is a common causative microorganism in prosthetic joint infections (PJIs). A high proportion of PJI isolates have been shown to harbor genetic traits associated with resistance to/tolerance of agents used for antimicrobial prophylaxis in joint arthroplasties. These traits were found within multidrug-resistant S. epidermidis (MDRSE) lineages of multiple genetic backgrounds. In this study, the aim was to study whether MDRSE lineages previously associated with PJIs are present in the nasal and skin microbiota of patients planned for arthroplasty surgery but before hospitalization. We cultured samples from nares, inguinal creases, and skin over the hip or knee (dependent on the planned procedure) taken two weeks (median) prior to admittance to the hospital for total joint arthroplasty from 66 patients on agar plates selecting for methicillin resistance. S. epidermidis colonies were identified and tested for the presence of mecA. Methicillin-resistant S. epidermidis (MRSE) were characterized by Illumina-based whole-genome sequencing. Using this method, we found that 30/66 (45%) of patients were colonized with MRSE at 1–3 body sites. A subset of patients, 10/66 (15%), were colonized with MDRSE lineages associated with PJIs. The qacA gene was identified in MRSE isolates from 19/30 (63%) of MRSE colonized patients, whereas genes associated with aminoglycoside resistance were less common, found in 11/30 (37%). We found that MDRSE lineages previously associated with PJIs were present in a subset of patients’ pre-admission microbiota, plausibly in low relative abundance, and may be selected for by the current prophylaxis regimen comprising whole-body cleansing with chlorhexidine-gluconate containing soap. To further lower the rate of S. epidermidis PJIs, the current prophylaxis may need to be modified, but it is important for possible perioperative MDRSE transmission events and specific risk factors for MDRSE PJIs to be investigated before reevaluating antimicrobial prophylaxis.

Failure After 2-Stage Exchange Arthroplasty for Treatment of Periprosthetic Joint Infection: The Role of Antibiotics in the Cement Spacer

BACKGROUND

Failure after a 2-stage exchange surgery for periprosthetic joint infection (PJI) is high. Previous studies demonstrated that positive cultures at reimplantation are associated with failure afterward. The aim of this multicenter study was to define the role of antibiotics in the cement spacer in relation to reimplantation cultures and subsequent failure.

METHODS

We retrospectively evaluated 2-stage exchange procedures between 2000 and 2015. Culture-negative PJIs, cases in which no cultures were obtained during reimplantation, and cases without data on cement spacers were excluded.

RESULTS

Three hundred forty-four cases were included. The rate of positive cultures during reimplantation was 9.5% for cement spacers containing a glycopeptide (27/284) (with or without an aminoglycoside) vs 21.7% for those containing monotherapy with an aminoglycoside (13/60) (P = .008), and was mostly attributed by a reduction in coagulase-negative staphylococci (CoNS) (17% vs 2%, P < .001). The failure rate was >2-fold higher at 40.0% (16/40) in cases with positive cultures at reimplantation compared to 15.8% (48/304) for those with negative cultures (P < .001). Overall, a glycopeptide in the cement spacer was not associated with a lower failure rate (18% vs 23%, P = .3), but was associated with lower failure due to CoNS (2.5% vs 13.3%, P < .001).

CONCLUSIONS

In a 2-stage exchange procedure for PJI, adding a glycopeptide to the cement spacer reduces the rate of positive cultures during reimplantation and is associated with a lower failure rate due to CoNS afterward.

Relationship between skin and urine colonization and surgical site infection in the proximal femur fracture: a prospective study

PURPOSE

Antibiotic prophylaxis is routinely used in the surgical management of proximal femur fractures. The role of bacterial colonization of the skin and urine in the development of deep surgical site infections (SSI) is yet to be elucidated. This study aimed to evaluate the role of previous skin and urine colonization in the development of deep SSI after a proximal femoral fracture surgery.

METHODS

We conducted a prospective observational study in 326 patients > 64 years old, who were scheduled to surgery. Cultures from skin samples of the surgical site and from urine were performed prior to the procedure, and cefazoline was administered as prophylaxis.

RESULTS

Skin microbiota was isolated in 233 (71.5%) cases; 8 (2.5%) samples were positive for other bacteria, and 85 (26%) were negative. Of 236 urine samples, 168 were negative or contaminated (71.2%), and 68 (28.8%) were positive, being 58/236 for Enterobacterales (24.6%). Acute deep SSI were diagnosed in nine out of 326 patients (2.7%), and two (22%) were infected by Gram-negative bacilli. Of the 9 cases, normal skin microbiota was isolated in 7 (78%), and the remaining two were negative. Seven cases had negative or contaminated urine cultures, and the one with E. coli did not correlate with SSI bacteria.

CONCLUSION

In our elderly hip fracture population, most patients harbored normal skin microbiota, and Enterobacterales urine cultures were positive in one-quarter of cases. There was no relationship between skin colonization, urine culture, and deep SSI. We therefore do not believe that our patients would benefit from modifying the current antibiotic prophylaxis.

Bioactive Glass Granules Inhibit Mature Bacterial Biofilms on the Surfaces of Cochlear Implants

HYPOTHESIS

Biofilm formation on cochlear implant (CI) surfaces differs between bacterial species and can be reduced by the application of S53P4 bioactive glass.

BACKGROUND

The formation of bacterial biofilms on medical devices, such as cochlear implants, can lead to chronic infections resulting in the need for implant removal. In this study, various surfaces of three CI implant kits from different manufacturers were examined for bacterial biofilm formation and reduction of a pre-existing biofilm by the application of bioactive glass.

METHODS

Biofilm formations of 4 bacterial species causing implant-related infections were tested on 17 different surfaces: Pseudomonas aeruginosa (ATCC9027), Staphylococcus aureus (ATCC6538), Staphylococcus epidermidis (ATCC12228), and Streptococcus pyogenes (ATCC19615). For P. aeruginosa and S. aureus biofilm reduction after application of S53P4 bioactive glass was evaluated.

RESULTS

All tested microbial species formed biofilms on the examined CI surfaces in a strain-dependent manner. For S. aureus, a significantly higher biofilm formation on metal components compared with silicone was found whereas the other strains did not show a material specific biofilm formation. Application of S53P4 bioactive glass resulted in a significant reduction of P. aeruginosa and S. aureus mature biofilm.

CONCLUSION

The four bacteria species displayed biofilm formation on the CI surfaces in a species- and material-specific manner. The results show that bioactive glass can reduce biofilm formation on CI materials in vitro. Future studies are necessary to confirm the results in vivo.

Two-stage revision arthroplasty for coagulase-negative staphylococcal periprosthetic joint infection of the hip and knee

BACKGROUND

Periprosthetic joint infections (PJIs) are frequently caused by coagulase-negative Staphylococci (CoNS), which is known to be a hard-to-treat microorganism. Antibiotic resistance among causative pathogens of PJI is increasing. Two-stage revision is the favoured treatment for chronic CoNS infection of a hip or knee prosthesis. We hypothesised that the infection eradication rate of our treatment protocol for two-stage revision surgery for CoNS PJI of the hip and knee would be comparable to eradication rates described in the literature.

AIM

To evaluate the infection eradication rate of two-stage revision arthroplasty for PJI caused by CoNS.

METHODS

All patients treated with two-stage revision of a hip or knee prosthesis were retrospectively included. Patients with CoNS infection were included in the study, including polymicrobial cases. Primary outcome was infection eradication at final follow-up.

RESULTS

Forty-four patients were included in the study. Twenty-nine patients were treated for PJI of the hip and fifteen for PJI of the knee. At final follow-up after a mean of 37 mo, recurrent or persistent infection was present in eleven patients.

CONCLUSION

PJI with CoNS can be a difficult to treat infection due to increasing antibiotic resistance. Infection eradication rate of 70%-80% may be achieved.