The present case series demonstrated that SA is linked with a high rate of 30-days mortality and a substantial 5-year mortality rate. Regarding outcomes, the 5-year survival rate was 71.7%, with an overall mortality of 28.3% at five years. Patients with age over 65 years (45.7%), arterial hypertension (43.2%), chronic heart failure (13.7%), chronic renal disease (7.1%), chronic liver disease (10.3%), peripheral vascular disease (11.5%), malignancy (13.7%), steroid use (25.7%), immunosuppression (10.0%), intraabdominal infection (7.1%;), sepsis (24.2%), septic shock (13.7%) and ICU admission (30.6%) had notably higher mortality rates.
(2) Risk factors for the in-hospital mortality of SA patients
In our cohort study, patients over the age of 65 years exhibited a considerable mortality rate of 45.7% (p < 0.001), highlighting the vulnerability of this age group. Furthermore, conditions such as arterial hypertension (43.2%; p = 0.003), chronic heart failure (13.7%; p = 0.001), chronic renal disease (7.1%; p < 0.001), chronic liver disease (10.3%; p = 0.013), peripheral vascular disease (11.5%; p = 0.026), malignancy (13.7%; p < 0.001), steroid use (25.7%; p < 0.001), immunosuppression (10.0%; p = 0.003), intraabdominal infection (7.1%; p = 0.049), sepsis (24.2%; p < 0.001), septic shock (13.7%; p = 0.049), and ICU admission (30.6%; p < 0.001) were significantly associated with increased mortality rates compared to patients without these conditions (Table 1).
Conversely, factors such as sex, previous hospitalization, and other comorbidities such as diabetes mellitus and rheumatological disease did not exhibit a statistically significant association with elevated mortality during the follow-up period. Notably, a significant correlation was identified between mortality and the CCI (ρ=-0.421; p < 0.001), emphasizing the importance of considering overall health status in prognostic assessments. Additionally, the ASA score among the 64 deceased individuals was found to be significantly higher, underscoring its potential as a predictive factor for adverse outcomes. This comprehensive analysis sheds light on the intricate interplay of various clinical parameters and their impact on mortality, providing valuable insights for risk stratification and patient management strategies.
Expanding our understanding of mortality in SA, existing literature indicates a 90-day mortality rate of 7%, escalating to 22%-69% in patients aged 80 and older [25]. In other studies comorbidities such as diabetes mellitus, rheumatoid arthritis, bacteremia, and low creatinine clearance are also linked to increased mortality [17]. Specifically, patients with rheumatoid arthritis experiencing joint flare-ups are identified as particularly high-risk individuals [26; 27].
Significant prognostic factors identified in the literature include increasing age (p < .001), female sex (p = .046), higher CCI scores (p < .001), and lacking private insurance [28]. Yeh et al.'s study on 52 dialysis patients with SA revealed tunneled cuffed catheter and fever as predictors of positive blood culture, with tunneled cuffed catheter being a predictor of in-hospital mortality [29]. A study examining SA in emergency departments in the United States revealed that the female sex, urban residence, treatment at a metropolitan teaching hospital, and the presence of medical comorbidities including diabetes mellitus, hyperlipidemia, hypertension, chronic obstructive pulmonary disease, coronary heart disease, gout, osteoarthritis, renal failure, and heart failure were associated with an elevated probability of hospitalization [30].
In line with prior investigations, our study recognized a similar pattern, with the knee emerging as the most frequently affected joint, closely followed by the shoulder. Specifically, 98 cases (51%) were related to the knee. A other study of 491 patients with SA, the knee emerged as the most frequently affected site, constituting 50.1% of cases, followed by the hip (14.4%), other anatomical locations (26.8%), the shoulder (5.5%), and involvement in multiple sites (1.2%) [15]. These findings align with current literature, emphasizing the significant prevalence of knee involvement [28; 31–33]. The richness of literature on native knee arthritis supports our findings, as it is recognized as the most commonly affected joint [1; 34–38].
Supporting the typical presentation, our study affirmed the predominant pattern of intra-articular infection, primarily characterized by monoarticular involvement. In alignment with established literature, our investigation also identified a congruent pattern, with approximately 20% of cases exhibiting participation in multiple joints, denoted as oligoarticular [9; 27].
In managing SA cases, our study employed arthroscopic or open surgical lavage in each case of SA. Several studies have conducted comparisons between operative intervention and medical therapy [39–41]. In one study, patients received empirical intravenous therapy with cloxacillin and ceftriaxone based on culture results, with treatment adjusted according to microbial sensitivity [41] .Meanwhile, another study assessed treatment failure after 7 days, with surgical treatment defined as a need for a second surgery [39]. Notably, in contrast to a study of Mabille et al about knee and hip arthritis [39], our observed median duration of hospitalization was a little bit higher, specifically 28.3 ± 23 days, with extremes ranging from 2 to 146 days. Mabille et al. found that the median duration of hospitalization was significantly higher in the surgical group compared to the medical group (33.5 vs. 21 days) [39]. This difference was primarily attributed to post-intervention follow-up, particularly the extended rehabilitation period in a rehabilitation center within the surgical group. These findings confirm data published by Ravindran et al., emphasizing the impact of surgical intervention on post-treatment care and rehabilitation needs [40]. Timely intervention is imperative, encompassing the initiation of antibiotics alongside surgical lavage and debridement [42]. Arthroscopic methodologies have demonstrated comparable efficacy to conventional open techniques, offering the supplementary advantages of shorter hospitalization periods and enhanced postoperative recuperation [1; 6; 36; 43–45]. The decision to utilize an arthroscopic approach is based on the discretion of the treating physician, with additional advantages including minimally invasive procedures, wound healing, functional outcomes, and reduced blood loss.
The etiology of SA often presents a diagnostic challenge, with a significant proportion of cases lacking an identified causative bacterial organism. However, when a pathogenic organism is identified, S. aureus emerges as the most prevalent, constituting 53% of the cases [9; 28; 29; 32; 36; 39]. In our study, consistent with existing literature, S. aureus was the predominant pathogen identified, comprising 31.3% of cases. These pathogens in SA are associated with elevated mortality rates and profound joint dysfunction [31]. Furthermore, S. aureus infections exhibit higher rates of cellulitis, abscess formation, and increased morbidity, leading to interventions such as fusion, amputation, or prosthetic joint replacement. Notably, drug-resistant strains, including MRSA, are becoming more prevalent, especially in intravenous (IV) drug users, with vancomycin-resistant strains observed in patients with recurrent healthcare-associated infections [46].
Other studies identified MRSA infections were frequently associated with oligoarticular arthritis, while group B streptococci were more prevalent in cases of oligoarticular arthritis compared to monoarticular septic arthritis [27; 47]. In our study, the three MRSA cases demonstrated oligoarticular arthritis. Moreover, streptococci cases exhibited a predominance in monoarticular cases (7 vs. 3), and a significant pattern was observed in S. aureus cases.
Understanding the microbial landscape of SA is crucial for tailoring effective treatment strategies, particularly in the context of emerging drug-resistant strains and the varied clinical manifestations associated with different pathogens. Further research is warranted to explore the evolving epidemiology of SA pathogens and their implications for patient outcomes.
Certain limitations should be acknowledged when interpreting the findings of this study. It is a single-center retrospective design, conducted in a German university hospital, may restrict the generalizability of findings to diverse populations. There is a potential for inherent selection bias as the study exclusively involves patients from an academic medical center, which could influence the observed severity and comorbidity profiles. The sample size of 192 patients, while relatively large compared to other studies, may still constrain the statistical robustness and broader generalizability of the findings. Diagnostic challenges in identifying SA, despite efforts to ensure accuracy, could lead to misclassifications or underdiagnoses. Dependence on electronic health records introduces the potential for data gaps or incompleteness, thereby influencing the precision of comorbidity assessments. The minimum follow-up period of 24 months may not adequately capture long-term outcomes, and statistical methods, while robust, lack specific details.