Microbiological Profile and Clinical Features of Septic Arthritis of the Shoulder: A 10-Year Cohort Single-Centre Study.

Introduction  Septic arthritis (SA) constitutes a pressing orthopedic emergency characterized by acute, non-traumatic joint pain. Timely diagnosis and intervention are imperative to avert complications such as chondrolysis and systemic sepsis. The etiology is predominantly hematogenous, necessitating an integrated approach involving surgical and microbiological modalities. Shoulder aspiration and microbiological analysis play pivotal roles in guiding treatment, especially when positive findings prompt more aggressive therapeutic strategies. This study aims to elucidate the nuanced clinical and epidemiological characteristics of septic arthritis in both native and prosthetic joints within a singular institutional cohort over a decade. Methods  This retrospective case series analysis spanned a 10-year period, focusing on non-prosthetic shoulder joints from January 2012 to July 2021. In this timeframe, only 183 aspirations were performed and sent to the microbiology department for analysis, including cultures, microscopy, and antibiotic sensitivity tests for positive cultures. The study delved into the microbiological profile of infections, encompassing gram stain, culture positivity rates, identification of microorganisms, and antibiotic susceptibility patterns. Additionally, the incidence of primary joint infections with resistant strains, particularly methicillin-resistant Staphylococcus aureus  (MRSA), was scrutinized. Statistical analysis utilized the SPSS program version 20.0 (IBM Inc., Armonk, New York), with a significance level set at 5%. The project, registered with the trust's clinical audit department (Reg #5372), adhered to the Declaration of Helsinki and good clinical practice guidelines. Data collection involved extracting non-identifiable patient modifiers from the laboratory database bank into Excel spreadsheets. Results  The study included 183 patients, with 108 (59%) females and 75 (41%) males. The average age was 76.2±16.5 years. Among them, 138 (75.4%) reported pain, and 15 (8.2%) had a body temperature over 37.8°C. Lab results showed a mean white blood cell count of 11.6±4.5 and an average C-reactive protein level of 121.7±102.1. Leucocytosis (>11,000 WBC) was seen in 82 (44.8%) cases. Elevated C-reactive protein (CRP; >10 mg/dl) was found in 136 (74.3%) patients. Synovial fluid analysis revealed no crystals in 91.3% of cases. Microbial resistance analysis showed 19 strains resistant to co-trimoxazole and 11 to erythromycin. Among co-trimoxazole-resistant strains, 73.7% were Staphylococcus aureus , a statistically significant association (p<0.001). Conclusion The evolving sensitivity patterns of microbes in septic arthritis underscore the necessity to reassess empirical antibiotic therapy. Subsequent joint damage resulting from infection can result in substantial disability.