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Background Staphylococcus aureus is the leading cause of prosthetic joint infection (PJI). Beyond the antibiogram, little attention has been given to the influence of deep microbiological characteristics on patient’s prognosis. Our aim was to investigate whether microbiological genotypic and phenotypic features have a significant influence on infection pathogenesis and patient outcome. Methods prospective multicentre study was performed, including all S. aureus PJIs (2016-2017). Clinical data, phenotypic (agr functionality, β-hemolysis, biofilm formation) and genotypic characteristics of the strains were collected. Biofilm susceptibility to antimicrobials was investigated (MBEC assay). Results 88 patients (39.8% men, age 74.7±14.1 years) were included. Forty-five had early post-operative (EPI), 21 chronic (CPI), and 19 hematogenous infections (HI). Twenty (22.7%) were caused by MRSA. High genotypic diversity was observed, including 16 clonal complexes (CC), CC5 being the most frequent (30.7%). agr activity was greater in EPI than CPI (55.6% vs 28.6%, p=0.041). Strains causing EPI were phenotypically and genotypically similar, regardless of symptom duration. Treatment failure (36.5%) occurred less frequently among cases treated with implant removal. In cases treated with debridement and implant retention, there were fewer failures among those who received combination therapy with rifampin. No genotypic or phenotypic characteristics predicted failure, except vancomycin MIC>=1.5 mg/L (23.1% failure vs 3.4%, p=0.044). MBEC50 was >128 mg/L for all antibiotics tested and showed no association with prognosis. Conclusions S. aureus with different genotypic backgrounds is capable of causing PJI, showing slight differences in clinical presentation and pathogenesis. No major microbiological characteristics were observed to influence the outcome, including MBEC.

Lactococcus garvieae is a Gram-positive, catalase negative coccus arranged in pairs or short chains, well-known as a fish pathogen. We report a case of Infective Endocarditis (IE) by L. garvieae in a native valve from a 68-year-old male with unknown history of contact with raw fish and an extensive history of heart disease. This case highlights the reliability of MALDI-TOF MS compared to conventional methods in the identification of rare microorganisms like this.

Abstract Aims Patients with infective endocarditis (IE) frequently have cardiac implantable electronic devices (CIEDs). Here, we aim to define the clinical profile and prognostic factors of IE in these patients. Methods and results Infective endocarditis cases were prospectively identified in the Spanish National Endocarditis Registry. From 3996 IE, 708 (17.7%) had a CIED and 424 CIED-related IE (lead vegetation). Patients with a CIED were older (68 ± 11 vs. 73 ± 8 years); had more comorbidities {pulmonary disease [176 (24.8%) vs. 545 (16.7%)], renal disease [239 (33.8%) vs. 740 (22.7%)], diabetes [248 (35.0%) vs. 867 (26.6%)], and heart failure [348 (49.2%) vs. 978 (29.9%)]}; and fewer complications {intracardiac destruction [106 (15%) vs. 1077 (33.1%)], heart failure [215 (30.3%) vs. 1340 (41.1%)], embolism [107 (15.1%) vs. 714 (21.9%)], and neurological involvement [77 (10.8%) vs. 702 (21.5%)]} (all P-values <0.001) in comparison to subjects without a CIED. In-hospital mortality was similar in patients with and without CIED [171 (24.2%) vs. 881 (27.0%), P = 0.82]. In subjects with a CIED, CIED-related IE was independently associated with in-hospital survival: odds ratio (OR) 0.4 [95% confidence interval (CI) 0.3–0.7, P = 0.001]. Surgery was independently associated with in-hospital survival in CIED-related IE: OR 0.4 (95% CI 0.2–0.7, P = 0.004); but not in subjects with valve IE and no CIED lead involvement: OR 0.9 (95% CI 0.5–1.7, P = 0.77). Conclusion Over a sixth of IE patients have a CIED. This group of patients is older, with more comorbidities and fewer IE-related complications in comparison to subjects without a CIED. In-hospital mortality was similar in patients with and without a CIED.