User:Mgeorgis/sandbox

Septic arthritis, also known as joint infection or infectious arthritis, is the invasion of a joint by an infectious agent resulting in joint inflammation. 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. The knee is the most commonly affected joint. (doesthispatienthave)

Causes include bacteria, viruses, fungi, and parasites. (add harrisons) Risk factors include an artificial joint, prior arthritis, diabetes, and poor immune function. (add up to date) Most commonly joints becomes infected via the blood but may also become infected via trauma or an infection around the joint. Diagnosis is generally based on culturing the joint fluid. White blood cells of greater than 50,000 mm3 or lactate greater than 10 mmol/l in the joint fluid also makes the diagnosis likely.

Initial treatment typically includes antibiotics such as vancomycin, ceftriaxone, or ceftazidime. (uptodate) Surgery may also be done to clean out the joint. Without early treatment, long term joint problems may occur. Septic arthritis occurs in about 5 out of every 100,000 people each year. It occurs more commonly in elderly people. '''Mortality is about 15% with treatment and 66% without treatment. (add acute septic arthritis)'''

Contents
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 * 1 Classification
 * 1Signs and symptoms
 * 2Cause
 * 2.1 Risk Factors
 * 2.2 Organisms
 * 3Diagnosis
 * 3.1Joint aspiration
 * 3.2Blood tests
 * (3.3Gonococcal arthritisXX)
 * 3.4Imaging
 * (3.5ClassificationXX)
 * 3.6 Differential Diagnosis
 * 4Treatment
 * 5Outcomes
 * 5References
 * 6External links

Classification
Septic arthritis is usually caused by bacteria, but may be caused by viral, mycobacterial, and fungal pathogens as well. (A broader term is "infectious arthritis", which describes arthritis caused by any infectious organism. Viruses can cause arthritis, but it can be hard to determine if the arthritis is directly due to the virus or if the arthritis is reactive.)XXX

Nongonoccocal Arthritis
'''These bacteria account for over 80% of septic arthritis cases and are usually staphyloccoci or streptococci. (approach) It is commonly spread through the blood from an infection site elsewhere, but can be introduced directly into the joint or from surrounding tissue. (harrisons)'''

Gonococcal Arthritis
'''Neisseria gonorrhoeae is a common cause of septic arthritis in sexually active patients under 40 years old. (approach, harrisons).The bacteria is spread through the blood to the joint following sexual transmission.''' Gonococcal septic arthritis may present in one of two possible ways:
 * Asymmetric polyarthritis, often associated with tenosynovitis and petechial skin rash
 * Isolated purulent monoarthritis, which in some cases may occur after the asymmetric polyarthritis

Other
'''Fungal and mycobacterial infections are rare causes of septic arthritis and usually have a slow onset of joint symptoms. (approach)'''

'''Borrelia burgodorferi infection, a bacteria that causes lyme disease, can affect multiple joints. (approach)'''

'''Viruses such as rubella, parvovirus B19, chikungunya, and HIV infection can also cause arthritis. (harrisons)'''

Signs and symptoms
Septic arthritis most commonly causes pain, swelling, and warmth at the affected joint. 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 patients. (doesthispatienthave).'''

'''The most common joint affected is the knee. Hip, shoulder, wrist, or elbow joints are less commonly affected. Spine, sternoclavicular, and sacroiliac joints can also be involved; however, the most common cause of arthritis in these joints is intravenous drug use. (harrisons)'''

'''Usually only one joint is effected. More than one joint can be involved if bacteria are seeded through the bloodstream. (harrisons)'''

Cause
'''Septic arthritis is most commonly caused by bacteria reaching the synovial membrane of a joint. Bacteria can enter the joint by:''' '''Micro-organisms in the blood may come from infections elsewhere in the body such as abscesses, wound infections, osteomyelitis, urinary tract infections, meningitis(17, approach), or endocarditis. Sometimes the infection comes from an unknown location. Joints with preexisting arthritis, such as rheumatoid arthritis, are especially prone to bacterial arthritis seeded through the blood stream. (6) In addition, some treatments for rheumatoid arthritis can also increase a patient's risk by causing an immunocompromised state. (approach) Intravenous drug use can cause endocarditis that seeds bacteria into the bloodstream and subsequently causes septic arthritis.'''
 * The bloodstream from an infection elsewhere (most common)
 * Direct penetration into the joint
 * A surrounding infection in the bone or tissue (uncommon). (7,8,13)(approach, harrisons)

'''Bacteria can enter the joint directly from prior surgery, intraarticular injection, trauma, or joint prosthesis. (harrisons, approach)'''

Risk Factors
Having more than one risk factor greatly increases risk of septic arthritis. (3)
 * Age over 80 years (3, approach)
 * Diabetes mellitus, (3, approach)
 * Osteoarthritis (approach)
 * Rheumatoid arthritis 3
 * Immunosuppressive medication (approch)
 * Intravenous drug abuse (approach)
 * Recent joint surgery 3,
 * Hip or knee prosthesis and skin infection 3, approach
 * HIV infection (3, approach)
 * Other causes of sepsis (approach)

Organisms
Most cases of septic arthritis involve only one organism; however, polymicrobial infections can occur, especially after large open injuries to the joint.(hospital medicine)
 * Staphyloccoci
 * Staphylococcus aureus - the most common cause in most age groups. Can be caused by skin infection, previously damaged joint, prosthetic joint, or intravenous drug use (uptodate, hospital medicine).
 * coagulase-negative staphylococci - usually due to prosthetic joint (harrisons)
 * Streptococci - the second most common cause (hospital medicine, approach)
 * Streptococcus pyogenes - a common cause in children under 5 (harrisons)
 * Streptococcus pneumoniae
 * Group B streptococci - a common cause in infants
 * Haemophilus influenzae (- was the most common cause in children, but is now uncommon in areas where Haemophilus vaccination is practiced)XXX
 * Neisseria gonorrhoeae-the most common cause of septic arthritis in young, sexually active adults. Multiple macules or vesicles seen over the trunk are a pathognomonic feature.
 * Neisseria meningitidis - (uptodate,hospitalmedicine)
 * Escherichia coli - in the elderly, IV drug users and the seriously ill
 * Pseudomonas aeruginosa - IV drug users or penetrating trauma through the shoe (hospital medicine, harrisons)
 * M. tuberculosis, Salmonella spp. and Brucella spp. - cause septic spinal arthritis
 * Eikenella corrodens - human bites (harrisons)
 * Pasteurella multocida, bartonella henselae - animal bites or scratches (harrisons)
 * Fungal species - immunocompromised state (up to date)
 * Borrelia burgodorferi - ticks, causes lyme disease (up to date)

(Micro-organisms must reach the synovial membrane of a joint. This can happen in any of the following

(Bacteria are either carried by the bloodstream from an infectious focus elsewhere, introduced directly by a skin lesion that penetrates the joint, or by extension from adjacent tissue (e.g. bone or bursae bovine tb).

( ways: Bacteria that are commonly found to cause septic arthritis are: In bacterial infection, Pseudomonas aeruginosa has been found to infect joints, especially in children who have sustained a puncture wound. This bacterium also causes endocarditis.)XXX
 * dissemination of pathogens via the blood, from abscesses or wound infections, or from an unknown focus
 * dissemination from an acute osteomyelitic focus,
 * dissemination from adjacent soft tissue infection,
 * entry via penetrating trauma
 * entry via health care associated means.
 * Staphylococcus aureus - the most common cause in adults
 * Streptococci - the second most common cause
 * Haemophilus influenzae - was the most common cause in children but is now uncommon in areas where Haemophilus vaccination is practiced
 * Neisseria gonorrhoeae-the most common cause of septic arthritis in young, sexually active adults. Multiple macules or vesicles seen over the trunk are a pathognomonic feature.
 * Escherichia coli - in the elderly, IV drug users and the seriously ill
 * M. tuberculosis, Salmonella spp. and Brucella spp. - cause septic spinal arthritis

Diagnosis
Septic arthritis should be considered whenever (one is assessing)XXX a person has rapid onset pain in a swollen joint, regardless of fever. One or multiple joints can be affected at the same time. (approach, doesthispatienthave, harrisons)

(Usually only one joint is affected however in seeding arthritis, several joints can be affected at the same time; this is especially the case when the infection is caused by staphylococcus or gonococcus bacteria.)XXX

The diagnosis of septic arthritis is based on physical exam and prompt arthrocentesis '''which yields synovial fluid from within the affected joint. This fluid should be collected before the administration of antibiotics and should be sent for gram stain, culture, leukocyte count with differential, and crystal studies. (uptodate, harrisons) This can include NAAT testing for N. gonorrhoeae if suspected in a sexually active patient (hospitalmedicine).'''

'''Other studies such as blood cultures, white blood cell count with differential, ESR, and CRP should also be included. However, these tests are nonspecific and could be elevated due to infection elsewhere in the body. Serologic studies should be done if lyme disease is suspected. (hospital medicine, harrisons).'''

In children, the Kocher criteria is used for diagnosis of septic arthritis.

(The diagnosis of septic arthritis can be difficult as no test is able to completely rule out the possibility. A number of factors should increase one's suspicion of the presence of an infection. In children these included in Kocher criteria. Diagnosis is by aspiration (giving a turbid, non-viscous fluid), Gram stain and culture of fluid from the joint.) XXX

Joint aspiration[edit]
In the joint fluid (aspirate)XXX, 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). 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. (add uptodate)

The Gram stain can rule in the diagnosis of septic arthritis, however, cannot exclude it.(add uptodate)

'''Synovial fluid cultures are positive in over 90% of nongonoccocal arthritis; however, it is possible for the culture to be negative if the patient received antibiotics prior to the joint aspiration. (uptodate, harrisons) Cultures are usually negative in gonoccocal arthritis or if fastidious organisms are involved. (uptodate, harrisons)'''

'''If the culture is negative or if a gonococcal cause is suspected, NAAT testing of the synovial fluid should be done. (harrisons)'''

'''Positive crystal studies do not rule out septic arthritis. Crystal induced arthritis such as gout can occur at the same time as septic arthritis. (approach)'''

A lactate level in the synovial fluid of greater than 10 mmol/l makes the diagnosis very likely.

Blood tests[edit]
Laboratory testing includes white blood cell count, ESR, and CRP. ((such as a highly elevated neutrophils (approx. 90%), ESR or CRP))XXX '''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. (uptodate, approach)''' Procalcitonin may be more useful than CRP.

'''Blood cultures can be positive in up to half of patients with septic arthritis. (approach, uptodate)'''

((Gonococcal arthritis[edit]
In the case of gonorrhea the knee or wrist may be chronically affected. The pain may be chronic and the physician may inject steroids to reduce symptoms. Weeks later increased pain, redness and swelling- signs of inflammation- appear leading to drainage by needle puncture. Then the gram stain and cultures are typical of a Neisserian infection.

Septic arthritis in a young, sexually active individual may be caused by Neisseria gonorrheae. Gonococcal septic arthritis may present in one of two possible ways: Diagnosis is confirmed by gram stain of the synovial fluid, blood cultures and urethral cultures.)XXX
 * Asymmetric polyarthritis, often associated with tenosynovitis and petechial skin rash
 * Isolated purulent monoarthritis, which in some cases may occur after the asymmetric polyarthritis

Imaging[edit]
'''Imaging such as x-ray, CT, MRI, or ultrasound are nonspecific. They can help determine areas of inflammation but cannot confirm septic arthritis. (acutesepticarhtiris)'''

'''When septic arthritis is suspected, x-rays should generally be taken. (uptodate). This is used to assess for involvement of surrounding structures such as bone and also for comparison purposes when future x-rays are taken (uptodate). While x-rays may not be helpful early in the diagnosis/treatment, they may show subtle increase in joint space and''' tissue swelling. '''(harrisons). Later findings include joint space narrowing due to destruction of the joint. (acutesepticarthritis)'''

'''Ultrasound can be done and is effective at detecting joint effusions. (acute septic arthritis)'''

'''CT and MRI are not required for diagnosis but can be used if diagnosis is unclear or in joints that are hard to examine (ie. sacroiliac or hip joints). They can can help assess for inflammation/infection in or about the joint (ie. osteomyeltis). (uptodate, acute septic arthritis). (acutesepticarthritis)'''

(Ultrasound may reveal joint effusion. Imaging can sometimes be used to aid in the diagnosis of septic arthritis. Native X-ray of the joint is neither sensitive nor specific. Ultrasound can detect joint-swelling. MRI findings include: synovial enhancement, perisynovial edema and joint effusion. Signal abnormalities in the bone marrow can indicate a concomitant osteomyelitis. The sensitivity and specificity of MRI for the detection of septic arthritis has been reported to be 67% and 98% respectively.)XXX

Differential Diagnosis

 * Crystal induced arthritis such as gout or pseudogout (uptodate, hosp)
 * Inflammatory arthritis (uptodate, hosp)
 * Rheumatoid arthritis
 * Seronegative spondyloarthropathy such as ankylosing spondylitis or reactive arthritis
 * Traumatic arthritis due to hemarthrosis, fracture, or foreign body (uptodate, hosp)
 * Osteoarthritis (uptodate, hosp)

(Classification[edit]
The term "suppurative arthritis" is a near synonym for septic arthritis. ("Suppurative" refers to the production of pus, without necessarily implying sepsis.)

ICD-10 uses the term "pyogenic arthritis". Pyogenic also refers to the production of pus.

Reactive arthritis refers to arthritis caused by an immune consequence of an infection, but not directly attributable to the infection itself.

Septic arthritis is usually caused by bacteria, but may be caused by viral, mycobacterial, and fungal pathogens as well. A broader term is "infectious arthritis", which describes arthritis caused by any infectious organism. Viruses can cause arthritis, but it can be hard to determine if the arthritis is directly due to the virus or if the arthritis is reactive.

Septic/suppurative arthritis and "bacterial arthritis" are sometimes considered equivalent, but there are exceptions. For example, Borrelia burgdorferi can cause infectious arthritis, but is not associated with suppurative arthritis.)xxx

Treatment[edit]
Treatment is usually with intravenous antibiotics, analgesia and washout and/or aspiration of the joint.( to dryness.)XX (uptodate, harrisons) Draining the pus from the joint is important and can be done either by needle (arthrocentesis) or opening the joint surgically (arthrotomy) (approach, uptodate).

'''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. (harrisons, approach) General guidelines are as follows:''' '''Once cultures are available, antibiotics can be changed to target the specific organism. (uptodate, harrisons)'''
 * Gram positive cocci - vancomycin (uptodate, approach)
 * Gram negative cocci - Ceftriaxone (approach)
 * Gram negative bacilli - Ceftrioxone, cefotaxime, or ceftazidime (uptodate)
 * Gram stain negative AND immunocompetent - vancomycin (uptodate)
 * Gram stain negative AND immunocompromised - vancomycin + third generation cephalosphorin (uptodate)
 * IV drug use (possible pseudomonas aeruginosa) - ceftazidime +/- an aminoglycoside (uptodate, harrisons)

'''After a good response to intravenous antibiotics, patients can be switched to oral antibiotics. The duration of oral antibiotics varies, but is generally for 1-4 weeks depending on the offending organism. (uptodate, harrisons, approach).'''

(Among pediatric patients with an acute hematogenous septic arthritis a short total course of 10 days of antimicrobials is sufficient in uncomplicated cases.) XX

In infection of a prosthetic joint, a biofilm is often created on the surface of the prosthesis which is resistant to antibiotics. Surgical debridement (or arthrotomy)xx is usually indicated in these cases. A replacement prosthesis is usually not inserted at the time of removal to allow antibiotics to clear infection of the region. (acutesepticarthritis). Patients that cannot have surgery may try long-term antibiotic therapy '''in order to suppress the infection. (acutesepticarthritis).'''

Close follow up with physical exam & labs must be done to make sure patient is no longer feverish, pain has resolved, has improved range of motion, and lab values are normalized.

Outcomes
'''Risk of permanent impairment of the joint varies greatly. 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 (acutesepticarthritis). Gonococcal arthritis generally does not cause long term impairment. (uptodate, harrisons, acute septic arthritis)'''

'''Mortality rates generally range from 10-20%. These rates increase depending on the offending organism, older age, and comorbidities such as rheumatoid arthritis(acutesepticarthritis, uptodate, hospital).'''