Septic arthritis | |
---|---|
Other names | Infectious arthritis, joint infection |
Septic arthritis as seen during arthroscopy [1] The arrow points to debris in the joint space. | |
Specialty | Orthopedic surgery |
Symptoms | Red, hot, painful single joint [2] |
Usual onset | Rapid [2] |
Causes | Bacteria, viruses, fungi, parasites [3] |
Risk factors | Artificial joint, prior arthritis, diabetes, poor immune function [2] |
Diagnostic method | Joint aspiration with culture [2] |
Differential diagnosis | Rheumatoid arthritis, reactive arthritis, osteoarthritis, gout [2] [3] |
Treatment | Antibiotics, surgery [2] |
Medication | Vancomycin, ceftriaxone, ceftazidime [2] |
Prognosis | 15% risk of death (treatment), 66% risk of death (without treatment) [2] |
Frequency | 5 per 100,000 per year [3] |
Acute septic arthritis, infectious arthritis, suppurative arthritis, pyogenic arthritis, [4] osteomyelitis, or joint infection is the invasion of a joint by an infectious agent resulting in joint inflammation. Generally speaking, symptoms typically include redness, heat and pain in a single joint associated with a decreased ability to move the joint. Onset is usually rapid. Other symptoms may include fever, weakness and headache. Occasionally, more than one joint may be involved, especially in neonates, younger children and immunocompromised individuals. [2] [3] [5] In neonates, infants during the first year of life, and toddlers, the signs and symptoms of septic arthritis can be deceptive and mimic other infectious and non-infectious disorders. [5]
In children, septic arthritis is usually caused by non-specific bacterial infection and commonly hematogenous, i.e., spread through the bloodstream. [6] [7] Septic arthritis and/or acute hematogenous osteomyelitis usually occurs in children with no co-occurring health problems. Other routes of infection include direct trauma and spread from a nearby abscess. Other less common cause include specific bacteria as mycobacterium tuberculosis, viruses, fungi and parasites. [3] In children, however, there are certain groups that are specifically vulnerable to such infections, namely preterm infants, neonates in general, children and adolescents with hematologic disorders, renal osteodystrophy, and immune-compromised status. In adults, vulnerable groups include those with an artificial joint, prior arthritis, diabetes and poor immune function. [2] Diagnosis is generally based on accurate correlation between history-taking and clinical examination findings, and basic laboratory and imaging findings like joint ultrasound. [5]
In children, septic arthritis can have serious consequences if not treated appropriately and timely. Initial treatment typically includes antibiotics such as vancomycin, ceftriaxone or ceftazidime. [2] Surgery in the form of joint drainage is the gold standard management in large joints like the hip and shoulder. [2] [5] [8] Without early treatment, long-term joint problems may occur, such as irreversible joint destruction and dislocation. [2]
In children septic arthritis usually affects the larger joints like the hips, knees and shoulders. The early signs and symptoms of septic arthritis in children and adolescents can be confused with limb injury. [5] Among the signs and symptoms of septic arthritis are: acutely swollen, red, painful joint with fever. [9] Kocher criteria have been suggested to predict the diagnosis of septic arthritis in children. [10]
Importantly, observation of active limb motion or kicking in the lower limb can provide valuable clues to septic arthritis of hip or knee. In neonates/new born and infants the hip joint is characteristically held in abduction flexion and external rotation. This position helps the infant accommodate maximum amount of septic joint fluid with the least tension possible. The tendency to have multiple joint involvements in septic arthritis of neonates and young children should be closely considered. [5]
In adults, septic arthritis most commonly causes pain, swelling and warmth at the affected joint. [2] [11] Therefore, those affected by septic arthritis will often refuse to use the extremity and prefer to hold the joint rigidly. Fever is also a symptom; however, it is less likely in older people. [12] In adults the most common joint affected is the knee. [12] Hip, shoulder, wrist and elbow joints are less commonly affected. [13] Spine, sternoclavicular and sacroiliac joints can also be involved. The most common cause of arthritis in these joints is intravenous drug use. [11] Usually, only one joint is affected. More than one joint can be involved if bacteria are spread through the bloodstream. [11]
For those with artificial joint implants, there is a chance of 0.86 to 1.1% of getting infected in a knee joint and 0.3 to 1.7% of getting infected in a hip joint.
There are three phases of artificial joint infection: early, delayed and late. [2]
Septic arthritis is most commonly caused by a bacterial infection. [14] Bacteria can enter the joint by:
Microorganisms in the blood may come from infections elsewhere in the body such as wound infections, urinary tract infections, meningitis or endocarditis. [13] Sometimes, the infection comes from an unknown location. Joints with preexisting arthritis, such as rheumatoid arthritis, are especially prone to bacterial arthritis spread through the blood. [13] In addition, some treatments for rheumatoid arthritis can also increase a person's risk by causing an immunocompromised state. [2] Intravenous drug use can cause endocarditis that spreads bacteria in the bloodstream and subsequently causes septic arthritis. [2] Bacteria can enter the joint directly from prior surgery, intraarticular injection, trauma or joint prosthesis. [11] [14] [15]
In children, although septic arthritis occurs in healthy children and adolescents with no co-occurring health issues, there are certain risk factors that may increase the likelihood of acquiring septic arthritis. For example, children with renal osteodystrophy or renal bone disease, certain hematological disorders and diseases causing immune suppression are risk factors for childhood septic arthritis. [5]
The rate of septic arthritis varies from 4 to 29 cases per 100,000 person-years, depending on the underlying medical condition and the joint characteristics. For those with a septic joint, 85% of the cases have an underlying medical condition while 59% of them had a previous joint disorder. [2] Having more than one risk factor greatly increases risk of septic arthritis. [13]
Most cases of septic arthritis involve only one organism; however, polymicrobial infections can occur, especially after large open injuries to the joint. [15] Septic arthritis is usually caused by bacteria, but may be caused by viral, [16] mycobacterial, and fungal pathogens as well. It can be broadly classified into three groups: non-gonococcal arthritis, gonococcal arthritis, and others. [2]
Type | WBC (per mm3) | % neutrophils | Viscosity | Appearance |
---|---|---|---|---|
Normal | <200 | 0 | High | Transparent |
Osteoarthritis | <5000 | <25 | High | Clear yellow |
Trauma | <10,000 | <50 | Variable | Bloody |
Inflammatory | 2,000–50,000 | 50–80 | Low | Cloudy yellow |
Septic arthritis | >50,000 | >75 | Low | Cloudy yellow |
Gonorrhea | ~10,000 | 60 | Low | Cloudy yellow |
Tuberculosis | ~20,000 | 70 | Low | Cloudy yellow |
Inflammatory: Arthritis, gout, rheumatoid arthritis, rheumatic fever |
Septic arthritis should be considered whenever a person has rapid onset pain in a swollen joint, regardless of fever. One or multiple joints can be affected at the same time. [2] [11] [12]
Laboratory studies such as blood cultures, white blood cell count with differential, ESR, and CRP should also be included. However, white cell count, ESR, and CRP are nonspecific and could be elevated due to infection elsewhere in the body. Serologic studies should be done if lyme disease is suspected. [11] [15] Blood cultures can be positive in 25 to 50% of those with septic arthritis due to spread of infection from the blood. [2] CRP more than 20 mg/L and ESR greater than 20 mm/hour together with typical signs and symptoms of septic arthritis should prompt arthrocentesis from the affected joint for synovial fluid examination. [9]
The synovial fluid should be collected before the administration of antibiotics and should be sent for gram stain, culture, leukocyte count with differential, and crystal studies. [11] [13] This can include NAAT testing for N. gonorrhoeae if suspected in a sexually active person. [15]
In children, the Kocher criteria is used for diagnosis of septic arthritis. [23]
The differential diagnosis of septic arthritis is broad and challenging. First, it has to be differentiated from acute hematogenous osteomyelitis. This is because the treatment lines of both conditions are not identical. Noteworthy, septic arthritis and acute hematogenous osteomyelitis can co-occur. Especially in the hip and shoulder joints their co-occurrence is likely and represents a diagnostic challenge. Therefore, physicians should have a high suspicion index in that regard. This is because in both the hip and shoulder joints the metaphysis is intra-articular which in turn facilitates the spread of hematogenous osteomyelitis into the joint cavity. Conversely, joint sepsis may spread to the metaphysis and induce osteomyelitis. [5] Acute exacerbation of juvenile idiopathic arthritis and transient synovitis of the hip both of which are non-septic conditions may mimic septic arthritis. More serious and life-threatening disorders as bone malignancies e.g. Ewing sarcoma and osteosarcoma may mimic septic arthritis associated with concurrent acute hematogenous osteomyelitis. In this regard, Magnetic resonance imaging may play an important role in the differential diagnosis. [5] [24]
In children, joint synovial fluid aspiration techniques aim at isolating the infectious organism by culture and sensitivity analysis. Cytological analysis of the joint aspirate can point to septic arthritis. However, a negative culture and sensitivity test does not rule out the presence of septic arthritis. Various clinical scenarios and technique-related factors may impact the validity of results of the culture and sensitivity. Additionally, results of cytological analysis, though important, should not be interpreted in isolation of the clinical settings. [5] [25]
In the joint fluid, the typical white blood cell count in septic arthritis is over 50,000–100,000 cells per 10−6/l (50,000–100,000 cell/mm3); [26] where more than 90% are neutrophils is suggestive of septic arthritis. [2] For those with prosthetic joints, white cell count more than 1,100 per mm3 with neutrophil count greater than 64% is suggestive of septic arthritis. [2] However, septic synovial fluid can have white blood cell counts as low as a few thousand in the early stages. Therefore, differentiation of septic arthritis from other causes is not always possible based on cell counts alone. [13] [26] Synovial fluid PCR analysis is useful in finding less common organisms such as Borrelia species. However, measuring protein and glucose levels in joint fluid is not useful for diagnosis. [2]
The Gram stain can rule in the diagnosis of septic arthritis, however, cannot exclude it. [13]
Synovial fluid cultures are positive in over 90% of nongonoccocal arthritis; however, it is possible for the culture to be negative if the person received antibiotics prior to the joint aspiration. [11] [13] Cultures are usually negative in gonoccocal arthritis or if fastidious organisms are involved. [11] [13]
If the culture is negative or if a gonococcal cause is suspected, NAAT testing of the synovial fluid should be done. [11]
Positive crystal studies do not rule out septic arthritis. Crystal-induced arthritis such as gout can occur at the same time as septic arthritis. [2]
A lactate level in the synovial fluid of greater than 10 mmol/L makes the diagnosis very likely. [27]
Laboratory testing includes white blood cell count, ESR and CRP. These values are usually elevated in those with septic arthritis; however, these can be elevated by other infections or inflammatory conditions and are, therefore, nonspecific. [2] [11] Procalcitonin may be more useful than CRP. [28]
Blood cultures can be positive in up to half of people with septic arthritis. [2] [13]
Imaging such as x-ray, CT, MRI or ultrasound are nonspecific. They can help determine areas of inflammation but cannot confirm septic arthritis. [14]
When septic arthritis is suspected, x-rays should generally be taken. [13] This is used to assess any problems in the surrounding structures [13] such as bone fractures, chondrocalcinosis, and inflammatory arthritis which may predispose to septic arthritis. [2] While x-rays may not be helpful early in the diagnosis/treatment, they may show subtle increase in joint space and tissue swelling. [11] Later findings include joint space narrowing due to destruction of the joint. [14]
Ultrasound is effective at detecting joint effusions. [14]
CT and MRI are not required for diagnosis; but if the diagnosis is unclear or the joints are hard to examine (ie.sacroiliac or hip joints); they can help to assess for inflammation/infection in or around the joint (i.e. Osteomyelitis), [13] [14] bone erosions, and bone marrow oedema. [2] Both CT and MRI scans are helpful in guiding arthrocentesis of the joints. [2]
Treatment is usually with intravenous antibiotics, analgesia and washout and/or aspiration of the joint. [11] [13] Draining the pus from the joint is important and can be done either by needle (arthrocentesis) or opening the joint surgically (arthrotomy). [2]
Empiric antibiotics for suspected bacteria should be started. This should be based on Gram stain of the synovial fluid as well as other clinical findings. [2] [11] General guidelines are as follows:
Once cultures are available, antibiotics can be changed to target the specific organism. [11] [13] After a good response to intravenous antibiotics, people can be switched to oral antibiotics. The duration of oral antibiotics varies, but is generally for 1–4 weeks depending on the offending organism. [2] [11] [13] Repeated daily joint aspiration is useful in the treatment of septic arthritis. Every aspirate should be sent for culture, gram stain, white cell count to monitor the progress of the disease. Both open surgery and arthroscopy are helpful in the drainage of the infected joint. During surgery, lysis of the adhesions, drainage of pus, and debridement of the necrotic tissues are done. [2] Close follow up with physical exam & labs must be done to make sure the person is no longer feverish, pain has resolved, has improved range of motion, and lab values are normalized. [2] [13]
In infection of a prosthetic joint, a biofilm is often created on the surface of the prosthesis which is resistant to antibiotics. [29] Surgical debridement is usually indicated in these cases. [2] [30] A replacement prosthesis is usually not inserted at the time of removal to allow antibiotics to clear infection of the region. [14] [30] People that cannot have surgery may try long-term antibiotic therapy in order to suppress the infection. [14] The use of prophylactic antibiotics before dental, genitourinary, gastrointestinal procedures to prevent infection of the implant is controversial. [2]
Low-quality evidence suggests that the use of corticosteroids may reduce pain and the number of days of antibiotic treatment in children. [31]
Risk of permanent impairment of the joint varies greatly. [13] This usually depends on how quickly treatment is started after symptoms occur as longer lasting infections cause more destruction to the joint. The involved organism, age, preexisting arthritis, and other comorbidities can also increase this risk. [14] Gonococcal arthritis generally does not cause long term impairment. [11] [13] [14] For those with Staphylococcus aureus septic arthritis, 46 to 50% of the joint function returns after completing antibiotic treatment. In pneumococcal septic arthritis, 95% of the joint function will return if the person survives. One-third of people are at risk of functional impairment (due to amputation, arthrodesis, prosthetic surgery, and deteriorating joint function) if they have an underlying joint disease or a synthetic joint implant. [2] Mortality rates generally range from 10 to 20%. [14] These rates increase depending on the offending organism, advanced age, and comorbidities such as rheumatoid arthritis. [13] [14] [15]
In children and adolescence septic arthritis and acute hematogenous osteomyelitis occurs in about 1.34 to 82 per 100,000 per annual hospitalization rates. [32] [33] [34] [35] In adults septic arthritis occurs in about 5 people per 100,000 each year. [3] It occurs more commonly in older people. [3] With treatment, about 15% of people die, while without treatment 66% die. [2]
Urethritis is the inflammation of the urethra. The most common symptoms include painful or difficult urination and urethral discharge. It is a commonly treatable condition usually caused by infection with bacteria. This bacterial infection is often sexually transmitted, but not in every instance; it can be idiopathic, for example. Some incidence of urethritis can appear asymptomatic as well.
Neisseria gonorrhoeae, also known as gonococcus (singular) or gonococci (plural), is a species of Gram-negative diplococci bacteria isolated by Albert Neisser in 1879. It causes the sexually transmitted genitourinary infection gonorrhea as well as other forms of gonococcal disease including disseminated gonococcemia, septic arthritis, and gonococcal ophthalmia neonatorum.
Tenosynovitis is the inflammation of the fluid-filled sheath that surrounds a tendon, typically leading to joint pain, swelling, and stiffness. Tenosynovitis can be either infectious or noninfectious. Common clinical manifestations of noninfectious tenosynovitis include de Quervain tendinopathy and stenosing tenosynovitis.
Nongonococcal urethritis (NGU) is inflammation of the urethra that is not caused by gonorrheal infection.
Bloodstream infections (BSIs) are infections of blood caused by blood-borne pathogens. The detection of microbes in the blood is always abnormal. A bloodstream infection is different from sepsis, which is characterized by severe inflammatory or immune responses of the host organism to pathogens.
Osteomyelitis (OM) is an infection of bone. Symptoms may include pain in a specific bone with overlying redness, fever, and weakness. The long bones of the arms and legs are most commonly involved in children e.g. the femur and humerus, while the feet, spine, and hips are most commonly involved in adults.
A limp is a type of asymmetric abnormality of the gait. Limping may be caused by pain, weakness, neuromuscular imbalance, or a skeletal deformity. The most common underlying cause of a painful limp is physical trauma; however, in the absence of trauma, other serious causes, such as septic arthritis or slipped capital femoral epiphysis, may be present. The diagnostic approach involves ruling out potentially serious causes via the use of X-rays, blood tests, and sometimes joint aspiration. Initial treatment involves pain management. A limp is the presenting problem in about 4% of children who visit hospital emergency departments.
Monoarthritis, or monoarticular arthritis, is inflammation (arthritis) of one joint at a time. It is usually caused by trauma, infection, or crystalline arthritis.
Staphylococcus lugdunensis is a coagulase-negative member of the genus Staphylococcus, consisting of Gram-positive bacteria with spherical cells that appear in clusters.
Rat-bite fever (RBF) is an acute, febrile human illness caused by bacteria transmitted by rodents, in most cases, which is passed from rodent to human by the rodent's urine or mucous secretions. Alternative names for rat-bite fever include streptobacillary fever, streptobacillosis, spirillary fever, bogger, and epidemic arthritic erythema. It is a rare disease spread by infected rodents and caused by two specific types of bacteria:
Brucella is a genus of Gram-negative bacteria, named after David Bruce (1855–1931). They are small, non-encapsulated, non-motile, facultatively intracellular coccobacilli.
Mediastinitis is inflammation of the tissues in the mid-chest, or mediastinum. It can be either acute or chronic. It is thought to be due to four different etiologies:
Prepatellar bursitis is an inflammation of the prepatellar bursa at the front of the knee. It is marked by swelling at the knee, which can be tender to the touch and which generally does not restrict the knee's range of motion. It can be extremely painful and disabling as long as the underlying condition persists.
Transient synovitis of hip is a self-limiting condition in which there is an inflammation of the inner lining of the capsule of the hip joint. The term irritable hip refers to the syndrome of acute hip pain, joint stiffness, limp or non-weightbearing, indicative of an underlying condition such as transient synovitis or orthopedic infections. In everyday clinical practice however, irritable hip is commonly used as a synonym for transient synovitis. It should not be confused with sciatica, a condition describing hip and lower back pain much more common to adults than transient synovitis but with similar signs and symptoms.
Gonorrhoea or gonorrhea, colloquially known as the clap, is a sexually transmitted infection (STI) caused by the bacterium Neisseria gonorrhoeae. Infection may involve the genitals, mouth, or rectum. Infected men may experience pain or burning with urination, discharge from the penis, or testicular pain. Infected women may experience burning with urination, vaginal discharge, vaginal bleeding between periods, or pelvic pain. Complications in women include pelvic inflammatory disease and in men include inflammation of the epididymis. Many of those infected, however, have no symptoms. If untreated, gonorrhea can spread to joints or heart valves.
Kingella kingae is a species of Gram-negative facultative anaerobic β-hemolytic coccobacilli. First isolated in 1960 by Elizabeth O. King, it was not recognized as a significant cause of infection in young children until the 1990s, when culture techniques had improved enough for it to be recognized. It is best known as a cause of septic arthritis, osteomyelitis, spondylodiscitis, bacteraemia, and endocarditis, and less frequently lower respiratory tract infections and meningitis.
A joint effusion is the presence of increased intra-articular fluid. It may affect any joint. Commonly it involves the knee.
Anaerobic infections are caused by anaerobic bacteria. Obligately anaerobic bacteria do not grow on solid media in room air ; facultatively anaerobic bacteria can grow in the presence or absence of air. Microaerophilic bacteria do not grow at all aerobically or grow poorly, but grow better under 10% carbon dioxide or anaerobically. Anaerobic bacteria can be divided into strict anaerobes that can not grow in the presence of more than 0.5% oxygen and moderate anaerobic bacteria that are able of growing between 2 and 8% oxygen. Anaerobic bacteria usually do not possess catalase, but some can generate superoxide dismutase which protects them from oxygen.
The Kocher criteria are a tool useful in the differentiation of septic arthritis from transient synovitis in the child with a painful hip. They are named for Mininder S. Kocher, an orthopaedic surgeon at Boston Children's Hospital and Professor of Orthopaedic Surgery at Harvard Medical School.
Prosthetic joint infection (PJI), also known as peri-prosthetic joint infection (PJI), is an acute, sub-acute or chronic infection of a prosthetic joint. It may occur in the period after the joint replacement or many years later. It usually presents as joint pain, erythema, joint swelling and sometimes formation of a sinus tract. PJI is estimated to occur in approximately 2% of hip and knee replacements, and up to 4% of revision hip or knee replacements. Other estimates indicate that 1.4-2.5% of all joint replacements worldwide are complicated by PJIs. The incidence is expected to rise significantly in the future as hip replacements and knee replacements become more common. It is usually caused by aerobic gram positive bacteria, such as Staph epidermidis or Staphylococcus aureus but enterococcus species, gram negative organisms and Cutibacterium are also known causes with fungal infections being a rare culprit. The definitive diagnosis is isolation of the causative organism from the synovial fluid, but signs of inflammation in the joint fluid and imaging may also aid in the diagnosis. The treatment is a combination of systemic antibiotics, debridement of infectious and necrotic tissue and local antibiotics applied to the joint space. The bacteria that usually cause prosthetic joint infections commonly form a biofilm, or a thick slime that is adherent to the artificial joint surface, thus making treatment challenging.
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