Practice Paper 2: Answers
Anthony B. Starr, Hiruni Jayasena, David Capewell, Saran Shantikumar in Get ahead! Medicine, 2016
Septic arthritis should always be considered with the presentation of a hot, swollen, tender joint with a restricted range of movement in the unwell patient. Septic arthritis is an infection within the synovial joint, most often caused by Staphylococcus aureus infection. It is most common in the hip and knee. Risk factors for developing septic arthritis include being very old or very young, intravenous drug use, diabetes and having pre-existing joint complaints. X-ray is normal in the early stages, but ultrasound and joint aspiration should be done to culture organisms. Management of septic arthritis is with surgical washout of the joint and intravenous antibiotics (e.g. flucloxacillin and benzylpenicillin) until the patient is clinically well, followed by a few weeks of oral antibiotics. Complications of septic arthritis include joint destruction (leading to arthritis), spread of infection to the bone (osteomyelitis) and ankylosis (bony fusion across the joint).
Bone and Joint Infections
Thomas T. Yoshikawa, Shobita Rajagopalan in Antibiotic Therapy for Geriatric Patients, 2005
Septic arthritis is an infection of the joint, and the elderly are at higher risk of developing bacterial arthritis. In a prospective study, age >80 years was found to be an independent risk factor to joint infections (1). The reported incidence of septic arthritis is 2-5 per 100,000 per year in the general population. The older population accounts for ≈25% of these cases (2,3). There is a high prevalence of joint disease in the elderly, and it is a well-known fact that diseased or damaged joints are more predisposed to infections. These arthropathies include rheumatoid arthritis, crystal arthropathies, prosthetic joints, osteoarthritis, and neuropathic joints (1,4). A prospective study of 154 patients with bacterial arthritis found that 40% had preexisting joint disease, mostly rheumatoid arthritis or degenerative arthritis (5). Also, the reported incidence of septic arthritis in patients with rheumatoid arthritis is as much as 10 times higher when compared with the general population (3). The pathogenesis of septic arthritis in the elderly may also be partly due to immunologic defects, since most of the other risk factors are associated with states of decreased immunity; for example, patients with diabetes mellitus or those on immunosuppressants are at risk of septic arthritis (3). Prosthetic joint placement also places the elderly at increased risk of septic arthritis, especially in those with rheumatoid arthritis (3,6).
Rheumatology
Keith Hopcroft in Instant Wisdom for GPs, 2017
If in any doubt about a patient presenting with a single hot swollen joint, refer urgently to exclude a septic arthritis. In primary care, the usual differential is gout, but the two conditions can be difficult to distinguish (see the ‘Easily Confused’ section below). Inflammatory arthritis is a risk factor for septic arthritis, so if a patient with known inflammatory arthritis presents with a single hot swollen joint, a septic joint must still be excluded – discuss with secondary care. Similarly, if apparent cellulitis presents over a joint and there is joint pain or swelling, consider whether the joint itself could be involved. Undertreating septic arthritis could result in chronic, irreversible damage to the joint.
Novel strategies to diagnose prosthetic or native bone and joint infections
Published in Expert Review of Anti-infective Therapy, 2022
Alex Van Belkum, Marie-Francoise Gros, Tristan Ferry, Sebastien Lustig, Frédéric Laurent, Geraldine Durand, Corinne Jay, Olivier Rochas, Christine C. Ginocchio
Septic arthritis is an inflammation of a joint that is caused by infection. Typically, septic arthritis affects one large joint in the body, such as the knee or hip. Risk factors for septic arthritis include hematogenous spread of pathogens (due to skin infection, cutaneous ulcers, or adjacent osteomyelitis), direct inoculation of pathogens (penetrating trauma, intrauricular injection, recent joint surgery) and higher age. Early stages of the disease include soft tissue swelling, purulence, and widening of joint space. If the disease is untreated it can progress to cartilage destruction, narrowing and irregularity of the joint space, bone destruction, and growth disturbances. Symptoms include pain, fever, restricted movement, swelling, effusion, and erythema. This category of infections is frequently culture negative (between 4.5% and 64%) [13]. Microorganisms involved most commonly are Staphylococcus aureus, coagulase-negative staphylococci, streptococci, enterococci, and several species of gram-negative bacteria and anaerobes. Acute arthritis in children less than 4 years old is frequently due to Kingella kingae and requires rapid antibiotic administration [14]. Neisseria gonorrhoeae, Neisseria meningitidis, or Mycobacterium spp. are less frequently isolated from arthritic patients [15]. Diagnosis mostly relies on arthrocentesis, i.e. joint fluid punctate analysis [16]. Synovial fluid examination includes microbiological, histological, and biochemical analyses. Time to result is key to rapidly initiating targeted antibiotic therapy.
Paediatric scurvy: frequently misdiagnosed
Published in Paediatrics and International Child Health, 2021
Husna Musa, Imma Isniza Ismail, Nurul Hazwani Abdul Rashid
Following extensive laboratory and radiological investigation, the initial differential diagnoses included inflammatory arthritis and septic arthritis. He underwent bilateral hip arthrotomy washout and biopsy which revealed minimal haemarthrosis with no bone abnormalities. The synovial fluid culture was negative (without preceding antibiotic treatment) and histopathological examination demonstrated mild chronic synovitis. In view of minimal improvement, further enquiry about his diet revealed that the child consumes hardly any fruit or vegetables. There had also been intermittent gum swelling and bleeding in the past 3 months. At this point, the diagnosis of scurvy was considered and blood was sent for quantification of ascorbic acid levels. The ascorbic acid level was subsequently found to be <5 µmol/L (28–120).
Assessing an alpha-defensin lateral flow device for diagnosing septic arthritis: reporting on a false-negative case and a false-positive case
Published in Modern Rheumatology Case Reports, 2020
Atsushi Narita, Akemi Suzuki, Taku Nakajima, Yuya Takakubo, Juji Ito, Akiko Sasaki, Michiaki Takagi
Septic arthritis represents a serious emergency which can result in mortality and significant morbidity [1]. Delayed or inappropriate treatment can cause irreversible joint destruction. Furthermore, an estimated 11% of cases result in mortality [2]. Therefore, early diagnosis and prompt and effective treatment are important to avoid severe outcomes. The definitive diagnosis of septic arthritis requires the direct demonstration of bacteria in the synovial fluid or the successful culturing of microorganisms from the synovial fluid. However, in 7–35% of previously reported cases of septic arthritis, no microorganisms have been identified [3]. Accurate diagnosis of septic arthritis can be difficult in certain patients and populations, especially in the elderly and those using immunosuppressive therapy [1].