Effect of Clinically Uninfected Orthopedic Implants and Pacemakers/AICDs in Low-Risk Staphylococcus aureus Bloodstream Infection on Crude Mortality Rate: A Post Hoc Analysis of a Large Cohort Study

Efficacy and safety of an early oral switch in low-risk Staphylococcus aureus bloodstream infection (SABATO): an international, open-label, parallel-group, randomised, controlled, non-inferiority trial

BACKGROUND

Staphylococcus aureus bloodstream infection is treated with at least 14 days of intravenous antimicrobials. We assessed the efficacy and safety of an early switch to oral therapy in patients at low risk for complications related to S aureus bloodstream infection.

METHODS

In this international, open-label, randomised, controlled, non-inferiority trial done in 31 tertiary care hospitals in Germany, France, the Netherlands, and Spain, adult patients with low-risk S aureus bloodstream infection were randomly assigned after 5-7 days of intravenous antimicrobial therapy to oral antimicrobial therapy or to continue intravenous standard therapy. Randomisation was done via a central web-based system, using permuted blocks of varying length, and stratified by study centre. The main exclusion criteria were signs and symptoms of complicated S aureus bloodstream infection, non-removable foreign devices, and severe comorbidity. The composite primary endpoint was the occurrence of any complication related to S aureus bloodstream infection (relapsing S aureus bloodstream infection, deep-seated infection, and mortality attributable to infection) within 90 days, assessed in the intention-to-treat population by clinical assessors who were masked to treatment assignment. Adverse events were assessed in all participants who received at least one dose of study medication (safety population). Due to slow recruitment, the scientific advisory committee decided on Jan 15, 2018, to stop the trial after 215 participants were randomly assigned (planned sample size was 430 participants) and to convert the planned interim analysis into the final analysis. The decision was taken without knowledge of outcome data, at a time when 126 participants were enrolled. The new sample size accommodated a non-inferiority margin of 10%; to claim non-inferiority, the upper bound of the 95% CI for the treatment difference (stratified by centre) had to be below 10 percentage points. The trial is closed to recruitment and is registered with ClinicalTrials.gov (NCT01792804), the German Clinical trials register (DRKS00004741), and EudraCT (2013-000577-77).

FINDINGS

Of 5063 patients with S aureus bloodstream infection assessed for eligibility, 213 were randomly assigned to switch to oral therapy (n=108) or to continue intravenous therapy (n=105). Mean age was 63·5 (SD 17·2) years and 148 (69%) participants were male and 65 (31%) were female. In the oral switch group, 14 (13%) participants met the primary endpoint versus 13 (12%) in the intravenous group, with a treatment difference of 0·7 percentage points (95% CI -7·8 to 9·1; p=0·013). In the oral switch group, 36 (34%) of 107 participants in the safety population had at least one serious adverse event compared with 27 (26%) of 103 participants in the intravenous group (p=0·29).

INTERPRETATION

Oral switch antimicrobial therapy was non-inferior to intravenous standard therapy in participants with low-risk S aureus bloodstream infection. However, it is necessary to carefully assess patients for signs and symptoms of complicated S aureus bloodstream infection at the time of presentation and thereafter before considering early oral switch therapy.

FUNDING

Deutsche Forschungsgemeinschaft.

TRANSLATIONS

For the German, Spanish, French and Dutch translations of the abstract see Supplementary Materials section.

Factors associated with foreign body infection in methicillin-resistant Staphylococcus aureus bacteremia

Background

We aimed to compare patient characteristics, MRSA sequence types, and biofilm production of MRSA strains that did and did not cause a foreign body infection in patients with MRSA bloodstream infections (BSI).

Methods

All adult patients with MRSA BSI hospitalized in two hospitals were identified by clinical microbiology laboratory surveillance. Only patients who had at least one implanted foreign body during the episode of BSI were included.

Results

In July 2018 - March 2022, of 423 patients identified with MRSA BSI, 118 (28%) had ≥1 foreign body. Among them, 51 (43%) had one or more foreign body infections. In multivariable analysis, factors associated with foreign body infection were history of MRSA infection in the last year (OR=4.7 [1.4-15.5], p=0.012) community-associated BSI (OR=68.1 [4.2-1114.3], p=0.003); surgical site infection as source of infection (OR=11.8 [2-70.4], p=0.007); presence of more than one foreign body (OR=3.4 [1.1-10.7], p=0.033); interval between foreign body implantation and infection <18 months (OR=3.3 [1.1-10], p=0.031); and positive blood culture ≥48h (OR=16.7 [4.3-65.7], p<0.001). The most prevalent sequence type was ST8 (39%), followed by ST5 (29%), and ST105 (20%) with no significant difference between patients with or without foreign body infection. Only 39% of MRSA isolates formed a moderate/strong biofilm. No significant difference was observed between patients with foreign body infection and those without foreign body infection. In multivariable analysis, subjects infected with a MRSA isolate producing moderate/strong in vitro biofilm were more likely to have a history of MRSA infection in the last year (OR=3.41 [1.23-9.43]), interval between foreign body implantation and MRSA BSI <18 months (OR=3.1 [1.05-9.2]) and ST8 (OR=10.64 [2-57.3]).

Conclusion

Most factors associated with foreign body infection in MRSA BSI were also characteristic of persistent infections. Biofilm-forming isolates were not associated with a higher risk of foreign-body infection but appeared to be associated with MRSA genetic lineage, especially ST8.

Clinically unsuspected orthopedic implants during S. aureus bacteremia do not require additional diagnostic work-up

PURPOSE

To assess the likelihood of occult infection in patients with clinically unsuspected orthopedic implants during Staphylococcus aureus bacteremia (SAB).

METHODS

In a retrospective study in two Dutch hospitals, we included all patients with SAB between 2013 and 2020 with one or more orthopedic implants in whom [¹⁸F]FDG-PET/CT was performed. The primary outcome was the percentage of patients who had an orthopedic implant-related infection by S. aureus. We also compared clinical parameters in patients with clinically suspected and unsuspected implants.

RESULTS

Fifty-five of 191 (29%) orthopedic implants in 118 SAB patients included had clinical signs of infection. Of all 136 unsuspected implants, 5 (3%, all arthroplasties), showed increased [¹⁸F]FDG uptake around the prosthesis on [¹⁸F]FDG-PET/CT. The clinical course of these patients without clinically overt infection or relapse of bacteremia during follow-up of a median of 48 months (range 0-48), however, argued against prosthetic joint infection.

CONCLUSION

Although orthopedic implants are evidently a risk factor for metastatic infection during SAB, the absence of clinical symptoms obviate the need of additional investigations or prolonged antibiotic treatment.

Risk of cardiac device-related infection in patients with late-onset bloodstream infection. Analysis on a National Cohort

OBJECTIVES

To determine the incidence of cardiac device-related infection (CDRI) among patients with cardiac device (CD) during late-onset bloodstream infection (BSI) and to identify the risk factors associated with CDRI.

METHODS

Patients with a CD (cardiac implantable electronic devices -CIED- and/or prosthetic heart valve -PHV-) and late-onset-BSI (>1 year after the CD implantation/last manipulation) were selected from the PROBAC project, a prospective, observational cohort study including adult patients with bacteraemia consecutively admitted to 26 Spanish hospitals from October 2016 to March 2017. Multivariate analyses using logistic regression were performed to identify the risk factors associated with CDRI.

RESULTS

317 BSI from patients carrying a CD were registered, 187 (56.2%) were late-onset-BSI. A total of 40 (21.4%) CDRI were identified during late-onset-BSI. The CDRI cumulative incidence in Gram-positive-BSI was 41.8% (38/91), with S. aureus, Enterococcus spp. and viridans streptococci showing the greatest percentages: 40% (12/30), 42% (11/26) and 75% (6/8), respectively. Independent predictors of CDRI were an unknown source of infection (OR: 2.88 [CI 95%:1.18-7.06], p=0.02), Gram-positive-aetiology (23.1 [5.23-102.1], p<0.001) and persistent bacteraemia (4.81 [1.21-19], p=0.03). In an exploratory analysis, S. aureus (3.99 [1.37-11.65], p=0.011), Enterococcus spp. (5.21 [1.76-15.4], p=0.003) and viridans streptococci (28.7 [4.71-173.5], p<0.001) aetiology were also found to be risk factors for CDRI.

CONCLUSIONS

CDRI during late-onset-BSI is a frequent phenomenon. Risk of CDRI differs among species, happening in almost half of the Gram-positive-BSI. An unknown source of the primary infection, Gram-positive-aetiology -especially S. aureus, Enterococcus spp. and viridans streptococci-, and persistent bacteraemia were identified as risk factors for CDRI.

骨科内植物表面抗菌改性的研究进展

OBJECTIVE

To summarize the related research progress of antibacterial modification of orthopaedic implants surface in recent years.

METHODS

The domestic and foreign related literature in recent years was extensively consulted, the research progress on antibacterial modification of orthopaedic implants surface was discussed from two aspects of characteristics of infection in orthopedic implants and surface anti-infection modification.

RESULTS

The orthopaedic implants infections are mainly related to aspects of bacterial adhesion, decreased host immunity, and surface biofilm formation. At present, the main antimicrobial coating methods of orthopaedic implants are antibacterial adhesion coating, antibiotic coating, inorganic antimicrobial coating, composite antimicrobial coating, nitric oxide coating, immunomodulation, three-dimensional printing, polymer antimicrobial coating, and "smart" coating.

CONCLUSION

The above-mentioned antibacterial coating methods of orthopedic implants can not only inhibit bacterial adhesion, but also solve the problems of low immunity and biofilm formation. However, its mechanism of action and modification are still controversial and require further research.

Protocol update for the SABATO trial: a randomized controlled trial to assess early oral switch therapy in low-risk Staphylococcus aureus bloodstream infection

BACKGROUND

SABATO (Staphylococcus aureus bacteremia antibiotic treatment options) is a randomized, parallel-group, clinical non-inferiority trial designed to examine the efficacy and safety of early oral switch therapy in low-risk Staphylococcus aureus infection. The original trial protocol was published in Trials (accessible at https://doi.org/10.1186/s13063-015-0973-x ). Here we describe final amendments to the study protocol and discuss the underlying rationale.

METHODS/DESIGN

Three major changes were introduced into the study protocol: (1) the inclusion and exclusion criteria were refined so that patients with certain comorbidities (end-stage renal disease, severe liver disease) and uninfected foreign bodies (orthopedic prosthesis, pacemaker, implanted cardiac cardioverter-defibrillator) became eligible for enrollment under certain conditions; (2) the target sample size was decreased by choosing a conventional non-inferiority margin of 10% and converting the interim analysis (215 patients) into the final analysis; and (3) an additional follow-up visit after 30 days was introduced to allow for a closer follow-up of patients.

CONCLUSION

Changes to the study protocol were introduced to improve the enrollment and follow-up of patients. Furthermore, the decrease of the sample size will facilitate completion of the trial.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01792804. Registered on 13 February 2013. German Clinical trials register, DRKS00004741. Registered on 4 October 2013, EudraCT 2013-000577-77.

Staphylococcus aureus Bloodstream Infection in Patients With Prosthetic Joints in the Prospective VIRSTA Cohort Study: Frequency and Time of Occurrence of Periprosthetic Joint Infection

Among 143 patients of the VIRSTA cohort study with Staphylococcus aureus bacteremia and an arthroplasty implanted for more than a year, S. aureus periprosthetic joint infection was observed in 19%. Signs of infection (pain and swelling) were always present, in median 1 day (range, 0–21 days) after onset of bacteremia.

Staphylococcus aureus has both a high potential for metastatic infection and a high affinity for foreign material. Possible prosthesis infection is of clinical concern in all patients with preexisting prosthetic materials experiencing S. aureus bloodstream infection (SAB). Prosthetic joints are especially prone to infection during the course of bacteremia, with a risk of infection much higher with S. aureus than with other microorganisms, 20% vs 7%, in a recent prospective study [1]. As early intervention with debridement in prosthetic joint infection (PJI) is paramount to retain the implant and to prevent infection relapse; eliminating PJI after SAB is important. However, additional data are needed to better describe the clinical characteristics of PJI after SAB in particular time lapses and whether systematic imaging of the prosthesis could be necessary after SAB. We described the frequency and clinical presentation of PJIs observed among patients with prosthetic joints implanted for >1 year before bacteremia and enrolled in the VIRSTA study, a multicenter prospective cohort study of patients with SAB.