Complicated septic arthritis—What all one can expect to see???
Septic arthritis refers to the articular manifestations due to the presence of a pathogen within a joint. In the majority of cases, the causative organism is a bacterium – the most common etiological agent in Europe and in the United States being Staphylococcus aureus. Most articular infections develop as a result of hematogenous seeding of the vascular synovial membrane after a bacteremia episode. Bacterial arthritis may also arise secondary to penetrating cutaneous trauma, following, for instance, a plant-thorn wound or an animal bite. Rarely, septic arthritis occurs as a result of local glucocorticoid joint injection or other intra-articular procedures. Intravenous (IV) drug users are also predisposed to develop this complication.
A 32-year-old male, IV drug user for 2 years presented with high-grade fever, swelling of left knee joint, left wrist accompanied with pain, periarticular redness, and decreased range of motion routine investigations revealed leukocytosis. Magnetic resonance imaging (MRI) left knee joint was suggestive of heterogeneous collection showing T1/T2 internal heterogeneity involving distal end of femur with underlying bone destruction, i.e. osteomyelitis with septic arthritis. Subsequently left knee arthrotomy with drainage was done Figure 1. Pus culture and blood culture showed the growth of S. aureus. The patient was managed with IV antibiotics depending on the sensitivity report. The patient went into septic shock and respiratory distress. IV antibiotics were upgraded, inotropes were started. Contrast-enhanced computed tomography chest was done which was suggestive of multiple parenchymal subpleural nodules, areas of consolidation with cavitations, with possibility of septic pulmonary emboli. During the hospital stay patient started complaining of decreased vision in both the eyes. Ophthalmology review revealed the findings suggestive of endophthalmitis. The patient was given intravitreal vancomycin twice and his vision showed marked improvement over the next week. The patient recovered from septic shock but continued to have persistent fever. Repeat blood culture, fungal culture was sterile. In view of persistent fever, two-dimensional echo was done which showed large vegetation at the posterior leaflet of tricuspid valve with moderate tricuspid regurgitation suggestive of infective endocarditis. IV antibiotics were upgraded. The patient was managed with the same for next 6 weeks. Subsequent echo showed marked decrease in the size of vegetation. The patient is currently stable afebrile and off antibiotics.
The occurrence of acute joint infection (septic arthritis) is 5–9/100,000 person-years (Margaretten et al., 2007). A high suspicion of septic arthritis is mandatory because the joint can be destroyed if the treatment is postponed for a few days. Patients with advanced age, rheumatoid arthritis (RA), and those who are immunocompromised or have abnormal joint structure or joint prosthesis are at increased risk for joint infection. Septic (purulent) arthritis is usually divided into two entities: (a) Non-gonococcal arthritis and (b) gonococcal arthritis Table 1. The division is useful in clinical practice because the risk factors, clinical features, and treatment differ greatly between the groups.
|Age||Risk increases with age||Sexually active young adults|
|Gender||No difference||×4 more common in female subjects|
|Menstruation||No increased risk||Increases risk|
|Complement deficiency, systemic lupus erythematosus||Risk for Neisseria meningitidis infection||Risk for Neisseria gonorrhoeae infection|
|Presentation||Single joint involvement||Migratory polyarthritis|
|Pustular dermatosis||Absent||Does occur|
|Culture positivity||Nearly 90%||<50%|
Clinical symptoms and diagnosis
Usually, the patient presents with an acutely swollen joint, often a large joint such as the knee or ankle. The joint is usually swollen, warm, can be even erythematous, tender on palpation, and on movement. The clinical presentation may vary according to the virulence of the causative organisms, which is low for mycobacterial and fungal infections. Infection in more than one joint occurs in about 20% of patients, most with underlying chronic disease, with an immunosuppressive state or drug abuse. If septic arthritis is suspected, arthrocentesis of the joint is mandatory, and the synovial fluid is analyzed for Gram-stain, white blood cell (WBC) count and differential, and cultured for bacteria. Staphylococci or streptococci cover about 91% of the infections. Gram-negative organisms are more common in older patients and in those who are immunocompromised than in younger patients. The Gram-stain is positive in 71% of Gram-positive septic arthritis, 40–50% of cases of Gram- negative septic arthritis, and in <25% of cases of gonococcal septic arthritis. The concentration of WBCs in the synovial fluid is usually increased, and a count of >50,000/ dl with >90% of polymorphonuclear cells increases the likelihood of septic arthritis. Evidence of infection should also be searched outside the joint (chest X-ray examination, cultures of urine, blood, throat, from possible wounds, skin blisters, etc.).
Radiography of the joint, while usually normal, unless there is a chronic rheumatic condition (RA, osteoarthritis, etc.), is of great use to exclude other diseases, such as underlying chondrocalcinosis, and to exclude the possibility of underlying osteomyelitis. The severity of the structural damage and the rate at which it appears varies according to the virulence of the pathogens and the intensity of joint inflammation. These changes include juxta-articular osteoporosis, a diffuse joint space narrowing due to cartilage destruction, and erosions in areas of reflection of the synovium into the bone. MRI or computed tomography are also of little help in diagnosing septic arthritis. They can be used to assess the presence and extent of inflammation, destruction, and especially, periarticular soft tissue masses.
A high suspicion of septic arthritis should prompt treatment with parenteral antibiotics without waiting for the results of bacterial cultures, and drainage of the infected joint, which are the cornerstones of the treatment. The decision about treatment can be guided by microscopy and routine analysis of the synovial fluid, but a negative Gram-stain does not exclude septic arthritis. The choice of antibiotic is primarily empirical and based on the likelihood of the organism involved, comorbidities, and on the local situation. When the culture results are available, the antibiotics can then be focused according to the sensitivity results. The duration of the IV treatment can be 10–14 days, often followed by oral antibiotics. The total duration of treatment, usually 6 weeks, depends on the infecting micro-organism, the other diagnoses and treatments, and the initial response to the treatment.
Articular – joint destruction, osteomyelitis, secondary osteoarthritis, avascular necrosis extra-articular – sepsis and septic shock, disseminated infection, endophthalmitis (rare).
Septic arthritis is a condition which requires prompt diagnosis and early institution of treatment to prevent permanent joint damage and various other extra-articular complications. Arthrocentesis is a must and treatment should be tailored according to the organism.
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Conflicts of interestThere are no conflicts of interest.
- Ann Rheum Dis. 2007;66:440-5Management of septic arthritis: A systematic review.
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