Rates and Predictors of Treatment Failure in Staphylococcus aureus Prosthetic Joint Infections According to Different Management Strategies: A Multinational Cohort Study—The ARTHR-IS Study Group

Introduction: Guidelines have improved the management of prosthetic joint infections (PJI). However, it is necessary to reassess the incidence and risk factors for treatment failure (TF) of Staphylococcus aureus PJI (SA-PJI) including functional loss, which has so far been neglected as an outcome. Methods: A retrospective cohort study of SA-PJI was performed in 19 European hospitals between 2014 and 2016. The outcome variable was TF, including related mortality, clinical failure and functional loss both after the initial surgical procedure and after all procedures at 18 months. Predictors of TF were identified by logistic regression. Landmark analysis was used to avoid immortal time bias with rifampicin when debridement, antibiotics and implant retention (DAIR) was performed. Results: One hundred twenty cases of SA-PJI were included. TF rates after the first and all surgical procedures performed were 32.8% and 24.2%, respectively. After all procedures, functional loss was 6.0% for DAIR and 17.2% for prosthesis removal. Variables independently associated with TF for the first procedure were Charlson >= 2, haemoglobin 30 kg/m(2) and delay of DAIR, while rifampicin use was protective. For all procedures, the variables associated with TF were haemoglobin < 10 g/dL, hip fracture and additional joint surgery not related to persistent infection. Conclusions: TF remains common in SA-PJI. Functional loss accounted for a substantial proportion of treatment failures, particularly after prosthesis removal. Use of rifampicin after DAIR was associated with a protective effect. Among the risk factors identified, anaemia and obesity have not frequently been reported in previous studies. [GRAPHICS]

High Incidence of Asymptomatic Phase I IgG Seroconversion After an Acute Q Fever Episode: Implications for Chronic Q Fever Diagnosis

[Background] The aim of this study was to describe the natural history of acute Q fever, including its clinical and serological evolution and progression to chronic Q fever.[Methods] Observational cohort study (January 2011–September 2020) performed at Valme University Hospital (Seville, Spain). Inclusion criteria: (1) patients aged ≥18 years; (2) acute Q fever diagnosis, defined as suggestive symptoms in the presence of phase II immunoglobulin G (IgG) titer >1:256; (3) at least 6 months’ follow-up after the acute Q fever episode. The incidence of seroconversion to a chronic Q fever serological pattern, defined as phase I IgG titers ≥1:1024 6 months after acute Q fever diagnosis, was assessed.[Results] During the study period, 117 patients were included. Thirty-four (29%) patients showed phase I IgG titers ≥1:1024 6 months after acute Q fever diagnosis. All patients with classic serological criteria for chronic Q fever diagnosis remained asymptomatic despite no specific treatment, with a median (quartile 1–quartile 3 [Q1–Q3]) follow-up of 26.5 (14–44) months in this subgroup. No cases of Q fever endocarditis nor other persistent focalized infection forms were observed during the study period.[Conclusions] A significant proportion of acute Q fever patients develop classic serological criteria for chronic Q fever diagnosis in the absence of additional data of chronic Q fever. Consequently, phase I IgG cutoff titers >1:800 should not be used as a criterion to consider such a diagnosis. The incidence of persistent focalized infection forms after acute Q fever is extremely low and does not justify the use of prophylaxis strategies.Peer reviewe