Rash and Joint Pain

This case highlights the potential complications of an everyday, childhood infection

Tommy, a 4 year old boy presented to the office with a chief complaint of right knee pain. His father reported Tommy was riding his bike last week when he drove the pedal of his bike into his calf. At the time of the incident there was some mild swelling and discomfort. A few days later, this same area turned into a purulent, fluid-filled blister. An X ray was done in the office showing a right knee joint effusion without acute fracture.

Soon thereafter, Tommy had developed right knee pain and swelling that progressed, involving the left ankle, right foot, left elbow and the left hand. In the meantime, Tommy started with cold-like symptoms including a runny nose, sore throat, vomiting and ear pain. A Rapid Strep test with reflux culture came back negative. A few days later, the patient’s cold-like symptoms completely resolved and he developed a purpura rash on the thighs, spreading to the groin and then distally to the lower extremities.

A few days following the onset of the rash, Tommy developed swelling and erythema in the scrotum and penis. He was started on Augmentin to treat what was thought to be Erysipelas. Tommy continued with intermittent swelling and erythema in the penis and scrotum over the next 4-5 days despite treatment efforts.

Tommy’s rash on the thighs and legs eventually evolved into tender, firm bruises on the lower extremities and his progressive joint pain and swelling persisted, becoming worse in the evenings and at times becoming so bad, his parents had to carry him to the bathroom because he would not walk. His scrotum, penile swelling and erythema eventually resolved after approximately 3-4 weeks of intermittent symptoms.

History & Physical

Tommy was otherwise a healthy, active boy. He was a twin, who was also described as being very healthy. Tommy had no previous major illnesses, accidents, surgeries or hospitalizations. He did not take any medications and had no allergies. He has a family history of a paternal grandmother and paternal aunt with Sjogren’s, but no other significant family history. Tommy lived in a rural setting in a home that was built in the early 1990’s. His water source came from a well. His family enjoyed camping in Wisconsin.

Besides the described symptoms above, Tommy’s review of systems was negative. His exam showed an alert, friendly, well-nourished and well developed 4 year old boy. Exam was significant for faint yellow-brown, nodular, tender ecchymosis scattered throughout the lower legs. He was able to move about the exam room and halls without difficulty. Tonsils 1+ without erythema, neck supple without lymphadenopathy, heart regular rate and rhythm without murmur, lungs were clear to auscultation, abdomen round, soft, non-tender without organomegaly.

Tommy’s EKG was within normal without prolonged P-R interval. An echocardiogram was normal without evidence of carditis, his CBC was normal with exception of a mildly depressed hemoglobin of 11.5 and slightly elevated platelet count of 479,000. He had the following additional lab studies: CMP, lipase, amylase, complement, ANA, coombs, Lyme titer, TB urine culture and anticoagulation studies which were all negative. Anti DNase 780 IU/ml and Antistreptolysin O (ASLO) was 848 IU/ml.

Disease Course

The patient was diagnosed with post streptococcal inflammatory arthritis (PSiA) based on his clinical presentation and elevated ALSO and anti-DNase.

He was started on prophylaxis Amoxicillin in effort to delay any further streptococcal infection while he was recovering. The patient’s symptoms had completely resolved approximately 1 month after initiation of the Amoxicillin and he remained asymptomatic thereafter.

Post infectious arthritis is defined as arthritis that develops at the time or soon after an infection elsewhere in the body, but is not able to be recovered from the joint.1,2,3

Streptococcal infections do not necessarily have to originate in the throat, but could be perirectal, perigenitalia regions as well as skin infections.4,5,6 In this case, the patient’s fluid filled blister that developed after falling off his bike was thought to be one potential source of the patient’s infection.

PSiA is a multisystem disease with symptoms ranging from sterile, painful joint effusions, skin infections, vasculitis-type rash, tenosynovitis, renal manifestations, urogenital involvement and pulmonary involvement.7,8 If left untreated, it can lead to pneumonia or even carditis which then would meet criteria for diagnosis of acute rheumatic fever (ARF).5

Diagnostic Criteria

There is not a widely accepted diagnostic criterion for PSiA at this time.1,4,5,6,9 Controversy of whether or not PSiA and ARF are the same thing exists among experts, however, post-streptococcal inflammatory arthritis does not fit the same criteria as the diagnosis of ARF.

There are clinical, immunological and genetic differences among the two diagnoses.1,2,3,6 In those with PSiA, the symptoms usually develop after a 7-10 day symptom-free period after the initial infection.1,6 Those patients with PSiA typically do not have high levels of inflammatory markers, their arthritis does not respond as well with non-steroidal anti- inflammatory drugs (NSAIDs) and very rarely is there cardiac involvement.1,2,3,6,9

Barash et al. suggested a mathematical formula based on four significant diagnostic discriminators to differentiate ARF from PSiA:1,2,3,6,10

-1.568 + 0.015 × ESR + 0.02 × CRP – 0.162 × days to resolution of joint symptoms – 2.04 × return of joint symptoms (yes = 1, No = 0)

If the result is greater than 0, the patient is classified as having ARF. If the result is 0, the patient is classified as having PSiA. Sensitivity of this formula was found to be 79% (correct classification of ARF) and specificity 87.5% for a correct classification of. 1,2,3,6,10

In order to diagnosis PSiA, it is important to confirm evidence of a prior GAS infection. This can be done using rapid antigen detection tests (RADT), throat or wound cultures, however, these tests are unable to distinguish between a true, acute case of GAS verses the 15% of children who are strep carriers.9

Elevated or increasing antistreptococcal antibody titers (ASLO) and antideoxyribosenuclease B (anti-DNase-B) can also help confirm GAS infection. ASLO titers begin to rise 1 week after infection and peaks at 3-6 weeks after infection. Anti-DNase-B begin to rise 1-2 weeks and peak 6-8 weeks after infection.6,11 However, elevated titers for both ASLO and anti-DNase-B can persist for months-years after GAS infection.1,2,3,6,9

It is best to repeat the ASLO titer 2-3 weeks after the initial test to confirm a recent strep infection by increasing levels. The symptoms of PSiA typically resolve spontaneously by 6-12 weeks, however, early intervention is encouraged.1,2,3,12

Treatment Recommendations

In 2009, the American Heart Association (AHA) released a statement recommending patients with PSiA be carefully observed for several months for clinical carditis.1,2,3,6

The AHA suggests that prophylaxis with Penicillin be given for 1 year after the onset of symptoms and discontinued if no evidence of carditis after 1 year.

If there has been any valvular involvement, the patient should be classified as having ARF and secondary prophylaxis should be initiated.1,3,6

Practice Implications

This case highlights the potential complications of an everyday, childhood infection.

When a patient, especially young child, presents with unusual joint pain, genitourinary infection and a rash it is important to gather a complete history including any previous infections in the last 1-2 months.

If there has been a recent infection or infectious symptoms, it is important to rule out and treat post-streptococcus inflammatory arthritis before symptoms progress into carditis.

NPs and PAs need to be aware of potential complications from streptococcal infections and be vigilant of such symptoms.


  1. Ayoub EM, et al. Update on complications of group A streptococcal infections. Curr Probl Pediatri. 1997;27(3):90-101.
  2. Barash J, et al. Differentiation of post-streptococcal reactive arthritis from acute rheumatic fever. J Pediatr. 2008;153(5):696-9.
  3. Gerber MA, et al. Prevention of rheumatic fever and diagnosis and treatment of acute Streptococcal pharyngitis: a scientific statement from the American Heart Association, Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee of the council on Cardiovascular Disease in the Young, the interdisciplinary council on Functional Genomics and Translational Biology, and the Interdisciplinary Council on Quality of Care and Outcomes Research: endorsed by the American Academy of Pediatrics. Circulation. 2009;119(11):1541-51. doi: 10.1161/CIRCULATIONAHA.109.191959.
  4. Hannu T. Reactive arthritis: best practice & research. Clinical Rheumatology. 2011;25:347.
  5. Livneh A, et al. Multisystem disease in post-streptococcal arthritis. Ann Rheum Dis. 1991;50:328-329.
  6. Uziel Y, et al. Post-streptococcal reactive arthritis in children: a distinct entity from acute rheumatic fever. Pediatr Rheumatol Online J. 2011; 9: 32..
  7. Sigal LH. Update on reactive arthritis. Bull Rheum Dis. 2001;50(4):1-4.
  8. Hahn R, et al. Evaluation of post streptococcal Illness. Am Fam Physician. 2005;71(10):1949-1954.
  9. Barash J. Rheumatic fever and post- group A streptococcal arthritis in children. Curr Infect Dis Rep. 2013;15:263-268. doi: 10.1007/s11908-013-0335-3.
  10. A.D.A.M.. Rheumatic Fever vs Post Strep Reactive Arthritis. 2009. http://www.pediatrics.org.il/specialization/Rheum%20Fever%20vs%20PSRA.pdf.
  11. Low DE. Nonpnuemococcal streptococal infection, rheumatic fever. In Goldman’s Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:1823-1829.
  12. John Hopkins Arthritis Center. Poststreptococcal Reactive Arthritis. April 10, 2007. http://www.hopkinsarthritis.org/ask-the-expert/poststreptococcal-reactive-arthritis/.

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