Orthopaedic implant-associated infections (OIAIs) due to Cutibacterium acnes can be difficult to diagnose. The aim of this pilot study was to determine if metagenomic next-generation sequencing (mNGS) can provide additional information to improve the diagnosis of C. acnes OIAIs. mNGS was performed on sonication fluid (SF) specimens derived from 24 implants. These were divided into three groups, based on culture results: group I, culture-negative (n = 4); group II, culture-positive for C. acnes (n = 10); and group III, culture-positive for other bacteria (n = 10). In group I, sequence reads from C. acnes were detected in only one SF sample, originating from a suspected case of OIAIs, which was SF and tissue culture-negative. In group II, C. acnes sequences were detected in 7/10 samples. In group III, C. acnes sequence reads were found in 5/10 samples, in addition to sequence reads that matched the bacterial species identified by culture. These samples could represent polymicrobial infections that were missed by culture. Taken together, mNGS was able to detect C. acnes DNA in more samples compared to culture and could be used to identify cases of suspected C. acnes OIAIs, in particular regarding possible polymicrobial infections, where the growth of C. acnes might be compromised due to a fast-growing bacterial species. However, since SF specimens are usually low-biomass samples, mNGS is prone to DNA contamination, possibly introduced during DNA extraction or sequencing procedures. Thus, it is advisable to set a sequence read count threshold, taking into account project- and NGS-specific criteria.

Oritavancin is a long-acting lipoglycopeptide with in vitro activity against Gram-positive pathogens, as well as good bactericidal activity and sterilisation ability in biofilm. It has been approved for acute bacterial skin and skin structure infections (ABSSSI), but recent reports have demonstrated possible off-label uses, such as for vancomycin resistant enterococci (VRE), deep-seated infections including those involving prosthetic material and invasive infections. The aim of this work is to review the uses of oritavancin outside of ABSSSI, focusing on its real-life applications on infective endocarditis, catheter- or device-related infections, bloodstream infections, and bone and prosthetic joint infections in humans, as well as possible future applications. We performed a narrative review, collecting the literature published between 1 December 2002 and 1 November 2022 on PubMed and the Cochrane Library using the term \'oritavancin\'. Available studies have shown how effective it is in different settings, suggesting an opportunity for step-down strategies or outpatient management of infections requiring a long duration of antibiotic treatment. So far, evidence is still scarce, and limited to a few studies and case reports, mostly focusing on Staphylococcus aureus as the major isolate. Concerns about fluid intake for dilution and interaction with coagulation markers also need to be taken into account. Further studies are required in order to assess the safety and effectiveness of Oritavancin in vascular, prosthetic, or device-related infections, as well as in resistant Gram-positive bacteria or enterococcal infections.

Staphylococcus aureus implant-associated infections are difficult to treat because of the ability of bacteria to form biofilm on medical devices. Here, the efficacy of Sb-1 to control or prevent S. aureus colonization on medical foreign bodies was investigated in a Galleria mellonella larval infection model. For colonization control assays, sterile K-wires were implanted into larva prolegs. After 2 days, larvae were infected with methicillin-resistant S. aureus ATCC 43300 and incubated at 37 °C for a further 2 days, when treatments with either daptomycin (4 mg/kg), Sb-1 (107 PFUs) or a combination of them (3 x/day) were started. For biofilm prevention assays, larvae were pre-treated with either vancomycin (10 mg/kg) or Sb-1 (107 PFUs) before the S. aureus infection. In both experimental settings, K-wires were explanted for colony counting two days after treatment. In comparison to the untreated control, more than a 4 log10 CFU and 1 log10 CFU reduction was observed on K-wires recovered from larvae treated with the Sb-1/daptomycin combination and with their singular administration, respectively. Moreover, pre-infection treatment with Sb-1 was found to prevent K-wire colonization, similarly to vancomycin. Taken together, the obtained results demonstrated the strong potential of the Sb-1 antibiotic combinatory administration or the Sb-1 pretreatment to control or prevent S. aureus-associated implant infections.

Periprosthetic infections are an eminent factor in patient care and also having significant economic implications. The number of biofilm-infection related replacement surgeries is increasing and will continue to do so in the following decades. To reduce both the health burden of the patients and the costs to the healthcare sector, new solutions for implant materials resistant to such infections are necessary. This study researches different surface modifications of cobalt-chromium-molybdenum (CoCrMo) based implant materials and their influence on the development of biofilms. Three smooth surfaces (CoCrMo, CoCrMo TiN, and CoCrMo polished) and three rough surfaces (CoCrMo porous coated, CoCrMo cpTi, and CoCrMo TCP) are compared. The most common infectious agents in periprosthetic infections are Staphylococcus aureus and Coagulase-negative staphylococci (e.g., Staphylococcus epidermidis), therefore strains of these two species have been chosen as model organisms. Biofilms were grown on material disks for 48 h and cell number, polysaccharide content, and protein contend of the biofilms were measured. Additionally, regulation of genes involved in early biofilm development (S. aureus icaA, icaC, fnbA, fnbB, clfB, atl; S. epidermidis atlE, aap) was detected using RT-q-PCR. All results were compared to the base alloy without modifications. The results show a correlation between the surface roughness and the protein and polysaccharide content of biofilm structures and also the gene expression of the biofilms grown on the different surface modifications. This is supported by the significantly different protein and polysaccharide contents of the biofilms associated with rough and smooth surface types. Additionally, early phase biofilm genes (particularly icaA, icaC, and aap) are statistically significantly downregulated compared to the control at 48 h on rough surfaces. CoCrMo TiN and polished CoCrMo were the two smooth surface modifications which performed best on the basis of low biofilm content.

One of the most serious complications following joint replacement surgeries are periprosthetic infections (PIs) arising from the adhesion of bacteria to the artificial joint. Various types of titanium-aluminum-vanadium (TiAl6V4) alloy surface modifications (coatings with silver (Ag), titanium nitride (TiN), pure titanium (cpTi), combinations of cpTi and hydroxyapatite (HA), combinations of cpTi and tricalcium phosphate (TCP), and a rough-blasted surface of TiAl6V4) have been investigated to assess their effects on biofilm development. Biofilms were grown, collected, and analyzed after 48 h to measure their protein and glucose content and the cell viability. Biofilm-associated genes were also monitored after 48 h of development. There was a distinct difference in the development of staphylococcal biofilms on the surfaces of the different types of alloy. According to the findings of this study, the base alloy TiAl6V4 and the TiN-coated surface are the most promising materials for biofilm reduction. Rough surfaces are most favorable when it comes to bacterial infections because they allow an easy attachment of pathogenic organisms. Of all rough surfaces tested, rough-blasted TiAl6V4 was the most favorable as an implantation material; all the other rough surfaces showed more distinct signs of inducing the development of biofilms which displayed higher protein and polysaccharide contents. These results are supported by RT-qPCR measurements of biofilm associated genes for Staphylococcus aureus (icaA, icaC, fnbA, fnbB, clfB, atl) and Staphylococcus epidermidis (atle, aap).

Biofilm-related infections are serious complications in the orthopaedic prosthetic field and an accurate, quick microbiological diagnosis is required to set up a specific antimicrobial therapy. It is well known that the diagnosis of these infections remains difficult due to the bacterial embedding within the biofilm matrix on the implant surfaces. Recently, the use of DL-dithiothreitol (DTT) has been proved effective in biofilm detachment from orthopaedic devices.The purpose of the study is to evaluate the efficacy of two DTT solutions enriched with specific broths for aerobic or anaerobic bacteria to dislodge pathogens from the biofilm, while supporting the bacterial recovery and viability. To do this, different experimental solutions were tested for efficacy and stability on strong biofilm producers: S. aureus and P. acnes. Mainly, we evaluate the capability of DTT dissolved in saline solution, brain heart infusion or thioglycollate broth to support the bacterial detachment from prosthetic materials and bacterial growth at different time points and storage conditions.We demonstrated that the use of DTT enriched with specific bacterial broths could be a suitable approach to optimize the bacterial detachment, recovery, growth and viability in the diagnosis of biofilm-related infections developed on orthopaedic prosthetic devices.