Genotypic and Phenotypic Characteristics of Staphylococcus aureus Prosthetic Joint Infections: Insight on the Pathogenesis and Prognosis of a Multicenter Prospective Cohort

Clinical outcomes of rifampicin combination therapy in implant-associated infections due to staphylococci and streptococci: A systematic review and meta-analysis

OBJECTIVES

Adjunctive rifampicin for implant-associated infections is controversial. This study investigated the clinical outcomes of rifampicin combination therapy compared with monotherapy in treating prosthetic joint infection (PJI) or prosthetic valve endocarditis (PVE) due to staphylococci and streptococci.

METHODS

A systematic search was performed from inception to 13 June 2022 in Embase, MEDLINE, Cochrane and Web of Science to investigate the clinical outcomes of rifampicin combination therapy compared with monotherapy in treating staphylococcal and streptococcal PJI or PVE. Randomised controlled trials (RCTs) and observational studies were included in the systematic review and meta-analysis.

RESULTS

Fourteen studies were included. A moderate quality of evidence was found in favour of rifampicin in patients with staphylococcal PJI who underwent a debridement, antibiotics and implant retention (DAIR) procedure [odds ratio = 2.49, 95% confidence interval (CI) 1.93-3.23]. Including the two RCTs only, adding rifampicin to the antibiotic regimen after DAIR was also in favour of rifampicin, but this was not statistically significant (risk ratio = 1.27, 95% CI 0.79-2.04; n = 126). Pooling data for patients with staphylococcal PJI who underwent a two-stage procedure showed that adding rifampicin was not associated with therapeutic success. Limited evidence was found for the use of rifampicin for PVE caused by staphylococci.

CONCLUSIONS

Adding rifampicin in the treatment of staphylococcal PJI treated by DAIR clearly increased the likelihood for therapeutic success. The clinical benefit of adjunctive rifampicin in the treatment of other staphylococci and streptococci implant-associated infections is still unclear.

Biofilm antimicrobial susceptibility testing: where are we and where could we be going?

Our knowledge about the fundamental aspects of biofilm biology, including the mechanisms behind the reduced antimicrobial susceptibility of biofilms, has increased drastically over the last decades. However, this knowledge has so far not been translated into major changes in clinical practice. While the biofilm concept is increasingly on the radar of clinical microbiologists, physicians, and healthcare professionals in general, the standardized tools to study biofilms in the clinical microbiology laboratory are still lacking; one area in which this is particularly obvious is that of antimicrobial susceptibility testing (AST). It is generally accepted that the biofilm lifestyle has a tremendous impact on antibiotic susceptibility, yet AST is typically still carried out with planktonic cells. On top of that, the microenvironment at the site of infection is an important driver for microbial physiology and hence susceptibility; but this is poorly reflected in current AST methods. The goal of this review is to provide an overview of the state of the art concerning biofilm AST and highlight the knowledge gaps in this area. Subsequently, potential ways to improve biofilm-based AST will be discussed. Finally, bottlenecks currently preventing the use of biofilm AST in clinical practice, as well as the steps needed to get past these bottlenecks, will be discussed.

Staphylococcus aureus Genomic Analysis and Outcomes in Patients with Bone and Joint Infections: A Systematic Review

Many studies have been published assessing the association between the presence of S. aureus genes and outcomes in patients with bone and joint infections (BJI), but it is not known if they have had similar findings. A systematic literature review was performed. All available data on studies in Pubmed between January 2000 to October 2022 reporting the genetic characteristics of S. aureus and the outcomes of BJIs were analyzed. BJI included prosthetic joint infection (PJI), osteomyelitis (OM), diabetic foot infection (DFI), and septic arthritis. Because of the heterogeneity of studies and outcomes, no meta-analysis was performed. With the search strategy, 34 articles were included: 15 articles on children and 19 articles on adults. In children, most BJI studied were OM (n = 13) and septic arthritis (n = 9). Panton Valentine leucocidin (PVL) genes were associated with higher biological inflammatory markers at presentation (n = 4 studies), more febrile days (n = 3), and more complicated/severe infection (n = 4). Other genes were reported anecdotally associated with poor outcomes. In adults, six studies reported outcomes in patients with PJI, 2 with DFI, 3 with OM, and 3 with various BJI. Several genes were associated with a variety of poor outcomes in adults, but studies found contradictory results. Whereas PVL genes were associated with poor outcomes in children, no specific genes were reported similarly in adults. Additional studies with homogenous BJI and larger sample sizes are needed.

Strain-to-strain variability among Staphylococcus aureus causing prosthetic joint infection drives heterogeneity in response to levofloxacin and rifampicin

INTRODUCTION

Levofloxacin and rifampicin are the preferred treatment for prosthetic joint infection (PJI) caused by Staphylococcus aureus, especially when managed with implant retention (DAIR). However, a significant variability of success has been reported, which could be related to intrinsic characteristics of the microorganism. Our aim was to evaluate the variability in the anti-biofilm response to levofloxacin and rifampicin in a clinical collection of S. aureus.

MATERIAL AND METHODS

Eleven levofloxacin- and rifampicin-susceptible S. aureus isolates causing PJI managed with DAIR were included. Levofloxacin, rifampicin and levofloxacin + rifampicin were tested in an in vitro static biofilm model in microtitre plates, where 48 h biofilms were challenged with antimicrobials during 24 h. Additionally, two genetically similar strains were tested in the CDC Biofilm Reactor, where 48 h biofilms were treated during 56 h. Antimicrobial activity was assessed by viable biofilm-embedded cells recount, and by crystal violet staining.

RESULTS

All antimicrobial regimens showed significant anti-biofilm activity, but a notable scattering in the response was observed across all strains (inter-strain coefficient of variation for levofloxacin, rifampicin and levofloxacin + rifampicin of 22.8%, 35.8% and 34.5%, respectively). This variability was tempered with the combination regimen when tested in the biofilm reactor. No correlation was observed between the minimal biofilm eradicative concentration and the antimicrobial activity. Recurrent S. aureus isolates exhibited higher biofilm-forming ability compared with strains from resolved infections (7.6 log10 cfu/cm2±0.50 versus 9.0 log10 cfu±0.07).

CONCLUSIONS

Significant variability may be expected in response to levofloxacin and rifampicin among biofilm-embedded S. aureus. A response in the lower range, together with other factors of bad prognosis, could be responsible of treatment failure.

Microbiological and Molecular Features Associated with Persistent and Relapsing Staphylococcus aureus Prosthetic Joint Infection

Background: Persistent and relapsing prosthetic joint infection (PJI) due to Staphylococcus aureus presents a clinical challenge. This study aimed to provide an extensive description of phenotypic and genomic changes that could be related to persistence or relapse. Methods: Initial and second S. aureus isolates from 6 cases of persistent and relapsing PJI, along with clinical isolates from 8 cases, with favorable outcome were included. All isolates were studied by phenotypic and genotypic approaches. Results: Recurrent S. aureus isolates exhibited a significant increase in adhesive capacity, invasion and persistence compared to resolved isolates. No association was found for the presence or absence of certain genes with the persistence or relapse of PJI. All sequential isolates showed identical sequence type (ST). Resistance gene loss during the infection and a great diversity of variants in different virulence genes between the pair of strains, mainly in genes encoding adhesins such as fnbA, were observed. Conclusions: S. aureus-caused relapse and persistence PJI is associated with bacterial phenotypical and genotypical adaptation. The main paths of adaptation were persistence in the intracellular compartment, and the loss of antibiotic resistance genes and variant acquisition, especially in genes encoding adhesins.

The Use of Rifampin in Total Joint Arthroplasty: A Systematic Review and Meta-Analysis of Comparative Studies

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication of total joint arthroplasty (TJA). Rifampin is an antibiotic with the ability to penetrate bacterial biofilms, and thus has been considered as a potentially important adjunct in the prevention and treatment of PJI. The aim of this systematic review is to evaluate and summarize the use of rifampin in TJA, particularly in the context of PJI.

METHODS

A literature search of all relevant electronic databases was performed. All comparative studies assessing the use of rifampin in the context of TJA were included. Descriptive data are reported, and a meta-analysis was performed using all studies which compared the addition of rifampin to standard care in treating PJI.

RESULTS

A total of 33 studies met inclusion criteria. A meta-analysis of 22 studies comparing the addition of rifampin to standard care for treating PJI found a significant reduction in failure rates (26.0% vs 35.9%; odds ratio 0.61, 95% confidence interval 0.43-0.86). The protective effect of rifampin was maintained in studies which included exchange arthroplasty as a treatment strategy, but not in studies only using an implant retention strategy. Among studies reporting adverse events of rifampin, there was a 20.5% adverse event rate.

CONCLUSION

Overall, rifampin appears to confer a protective effect against treatment failure following PJI. This treatment effect is particularly pronounced in the context of exchange arthroplasty. Further high-level evidence is needed to clarify the exact indications and doses of rifampin which can most effectively act as an adjunct in the treatment of PJI.

LEVEL OF EVIDENCE

Level III, Systematic Review and Meta-Analysis of Level I-III Studies.

Comparative Phenotypic and Genomic Features of Staphylococci from Sonication Fluid of Orthopedic Implant-Associated Infections with Poor Outcome

Staphylococcus spp. remain the leading biofilm-forming agents causing orthopedic implant-associated infections (OIAI). This is a descriptive study of phenotypic and genomic features identified in clinical isolates of S. aureus and coagulase-negative Staphylococcus (CoNS) recovered from OIAIs patients that progressed to treatment failure. Ten isolates were identified by matrix-time-of-flight laser-assisted desorption mass spectrometry (MALDI-TOF-MS) and tested for antibiotic susceptibility and biofilm formation. Genotypic characteristics, including, MLST (Multi Locus Sequence Typing), SCCmec typing, virulence and resistance genes were assessed by whole-genome sequencing (WGS). All S. aureus harbored mecA, blaZ, and multiple resistance genes for aminoglycosides and quinolones. All MRSA were strong biofilm producers harboring the complete icaADBC and icaR operon. Seven CoNS isolates comprising five species (S. epidermidis, S. haemolyticus, S. sciuri, S. capitis and S. lugdunensis) were analyzed, with mecA gene detected in five isolates. S. haemolitycus (isolate 95), and S. lugdunensis were unable to form biofilm and did not harbor the complete icaADBCR operon. High variability of adhesion genes was detected, with atl, ebp, icaADBC operon, and IS256 being the most common. In conclusion, MRSA and CoNS isolates carrying genes for biofilm production, and resistance to β-lactam and aminoglycosides are associated with treatment failure in OIAIs.

Antibacterial biomaterials in bone tissue engineering

Bone infection is a devastating disease characterized by recurrence, drug-resistance, and high morbidity, that has prompted clinicians and scientists to develop novel approaches to combat it. Currently, although numerous biomaterials that possess excellent biocompatibility, biodegradability, porosity, and mechanical strength have been developed, their lack of effective antibacterial ability substantially limits bone-defect treatment efficacy. There is, accordingly, a pressing need to design antibacterial biomaterials for effective bone-infection prevention and treatment. This review focuses on antibacterial biomaterials and strategies; it presents recently reported biomaterials, including antibacterial implants, antibacterial scaffolds, antibacterial hydrogels, and antibacterial bone cement types, and aims to provide an overview of these antibacterial materials for application in biomedicine. The antibacterial mechanisms of these materials are discussed as well.