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An Eleven-year-old Boy With Arthritis of the Hip Joint, and an 8-year-old Boy With Sacroiliitis

Mendo, Tânia MD*; Norte, Susana MD; Alves, Pedro MD; Tavares, Delfin MD; Pinto, Margarida MD§; Gouveia, Catarina MD*,∥

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The Pediatric Infectious Disease Journal: July 2021 - Volume 40 - Issue 7 - p 694-696
doi: 10.1097/INF.0000000000003040
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A previously healthy 11-year-old boy presented to the Emergency Department with severe right groin pain for 8 days and fevers (up to 39.5°C) for 4 days. He had been admitted to another hospital on day 4 of illness, where septic arthritis of the right hip was suspected. He underwent right hip arthrocentesis that revealed a purulent effusion collected for culture and was treated with flucloxacillin. After 4 days, no improvement was noted, and he was transferred to our hospital. The patient denied any animal contact, weight loss, sweats, or cough. He had a temperature of 39°C, blood pressure of 107/63 mm Hg, heart rate of 87 beats per minute, and respiratory rate of 20 breaths per minute. Physical examination revealed a patient that appeared pale and septic. He had hepatomegaly (with liver edge 3 cm below the costal margin) and held his right hip fixed in external rotation with severe limitation in the range of motion (ROM).

A radiograph of the right hip showed no evidence of bony lesions, but ultrasonography confirmed a heterogeneous 15.5 mm effusion. Laboratory findings included hemoglobin of 11.4 g/dL; white blood cell count at the lower limit of normal (4660 × 106/L) with differential of 55.3% neutrophils, 33.3% lymphocytes, 9.9% monocytes, 0.9% eosinophils, and 0.6% basophils; platelet count of 217 × 109/L; C-reactive protein of 24 mg/L (normal < 5 mg/L); and erythrocyte sedimentation rate of 71 mm/h (normal < 11 mm/h). Transaminases, serum electrolytes, and creatinine were all normal. EBV, HIV, parvovirus, M. pneumoniae, and Borrelia burgdorferi serologies and interferon-gamma release assay were negative. Antistreptolysin O and DNAseB were within normal levels. Urine leukocyte count was 18/µL (normal < 11/µL), with urinary protein/creatinine ratio of 0.2 (normal < 0.2). Rheumatoid factor and ANA were negative, but HLA B27 was positive. Transthoracic ultrasonography excluded endocarditis.

Due to concern of persistent septic arthritis, the patient underwent a repeat arthrocentesis, and clindamycin 40 mg/kg/d was added to flucloxacillin.

On day 7 of admission, the pain and right hip effusion persisted, with severe decrease in ROM. MRI of the hip showed a small right intra-articular effusion, with contrast uptake throughout the synovium, compatible with right hip synovitis, acetabulum hyperintensity with psoas tendon and adductors hyperintensity (Figure 1). He then underwent arthrotomy with irrigation and debridement.

MRI DP FS hip joint effusion. T2 and FS acetabulum hyperintensity (triradiate cartilage). Psoas tendon and adductors hyperintensity.


A 12-year-old, previously healthy boy presented to the Emergency Department with an intermittent, nonradiating, left groin pain for 9 months unrelated to trauma. He had low-grade fever (38°C axillary) off and on for 5 months and also noted weight loss (5 kg) and malaise. He lived in a rural area, but he denied any ingestion of unpasteurized food products or contact with animals. Physical examination showed axillary temperature of 36°C, blood pressure of 105/70 mm Hg, heart rate of 87 beats per minute, and respiratory rate of 16 breaths per minutes. He appeared well with normal physical examination except for left-sided limp and moderate pain on left hip flexion.

Radiograph and ultrasound of the hip were normal. Laboratory findings included hemoglobin of 12.9 g/dL; leukocyte count of 4610 × 106/L with differential of 52.9% neutrophils, 41.2% lymphocytes, 3.3% monocytes, 1.7% eosinophils, and 0.1% basophils; platelet count of 290 × 109/L; C-reactive protein of 0.31 mg/L (normal < 5.0 mg/L); and erythrocyte sedimentation rate of 42 mm/h (normal < 11mm/h). Transaminases, serum electrolytes, and creatinine were all normal. Blood culture, HIV serology, Borrelia burgdorferi serology, and interferon-gamma release assay were negative. Cardiac ultrasonography was normal.

MRI of the pelvis showed left sacroiliitis with effusion with anterior periarticular inflammation and nonspecific, “reactive” changes in the adjacent iliac bone (Figure 2). An additional test revealed the diagnosis.

Left infectious sacroiliitis with effusion.

For Denouement see P. 695.


Continued from P. 694.

In both cases, Rose Bengal agglutination test was positive for brucellosis with a titer of 1/160. Additionally, IgG and IgM were positive for Brucella spp. by ELISA test. In case 1, on day 7 of admission blood and synovial cultures grew Brucella mellitensis, but in case 2, cultures were negative. Treatment was switched to doxycycline and rifampicin for 6 weeks plus gentamicin for 7 days.

At 3 weeks of therapy, case 1 showed a clear improvement, with only a mild residual pain on external rotation, and after 3 months, he regained full hip ROM without any pain. Case 2 was discharged on day 15 of treatment with frank clinical improvement, with slight limitation of ROM but no pain. After 2 years, both patients had no evidence of sequelae, and Brucella serologies (ELISA) were negative.

Brucellosis is the most common zoonosis worldwide. It is caused by Brucella spp. a facultative intracellular, Gram-negative, coccobacillus, transmitted by direct contact with infected animal tissues or by the consumption of raw or unpasteurized dairy products.1

Worldwide around 500,000 cases of Brucellosis are diagnosed every year.2 The incidence varies from less than 0.03 to 160 per 100,000 habitants3 and is declining or eliminated in many developed countries, including most Northern European countries. According to the European Annual Epidemiological Report, the incidence in Europe varied between 0.1 and 0.08 per 100,000 from 2013 to 2018.4,5 Greece, Italy, Portugal, and Spain reported the highest notification rates, accounting for 70% of European cases.5 In Portugal, brucellosis is a notifiable disease, and after an incidence peak in the 80s and 90s, a decreasing trend for the past 20 years has been observed, with an incidence that varied between 0.16 and 0.48 per 100,000 from 2013 to 2018.4–6

Affected children are usually older, are of male gender, have a positive family history, and have had contact with animals (9%–51%) or dairy products (41%–83%) in a rural area.7,9 The disease spectrum is wide, ranging from asymptomatic disease to subacute and chronic forms, in which recurrent episodes over the years can be seen.1,7 The clinical presentation may be indolent with symptoms starting, on average, 30 days before diagnosis, and complaints are often vague such as fatigue, anorexia, weight loss, or sweats.1,7 Brucellosis may also present as a nonspecific multisystemic disease, with fever, arthralgia, and hepatomegaly.1,8 Hepatomegaly is present in 17%–74% of cases, and involvement of bones and joints, brain, and heart is commonly reported.8 Osteoarticular involvement occurs in 10%–85% of cases.1,7,9 Bosilkovski et al7 in a review of 133 pediatric osteoarticular brucellosis in Macedonia from 1989 to 2011, noted that osteoarticular involvement was the sole manifestation in 10.5% and was predominantly monoarticular (71.4%). Sacroiliitis, spondylodiscitis, and peripheral arthritis were the most common osteoarticular lesions.7 The most affected peripheral joints were the hip, knee, or ankle.7 The dominant manifestations were pain, swelling, and limited ROM, while redness and warmth were uncommon.7

Our patients were both male children, without a clear epidemiologic link, although case 2 was from a rural area in Portugal. In addition, their presentations were different, although both monoarticular. The first case presented with an acute, severe, monoarthritis and fever, very similar to S. aureus septic arthritis. In this case, the presence of hepatomegaly, absences of myositis or multifocal involvement, and the nonresponse to antistaphylococcal antibiotics might have been clues to Brucellosis. The second case had a nonspecific subacute course, which is more typical of brucellosis. Furthermore, in both cases, the mild leukopenia and high sedimentation rate could have also suggested the possibility of brucellosis.1,7

A definitive diagnosis requires isolation of Brucella from blood, synovial fluid, or bone. Cultures are positive in 50%–70% of the cases, and the yield of blood cultures varies between 15% and 70%, greater during the first week of disease.1 When bacteriologic confirmation is not possible, as in the second case, a presumptive diagnosis can be made by Brucella-specific agglutination methods demonstrating the presence of antibodies, such as the standard agglutination tests or Rose Bengal test. The Rose Bengal test allows detection of IgM and IgG with good correlation with serum agglutination. ELISA is useful in complicated, recurrent, and chronic infections. In both cases, Brucella-specific agglutination tests and ELISA were positive.

Different pediatric therapeutic protocols are used to treat brucellosis with osteoarticular involvement.1,7 A combination of 2 or 3 antimicrobial agents for at least 6 weeks is recommended, given the high relapse rates.7,10 The World Health Organization recommends a combination of doxycycline with rifampicin for 45 days as the treatment of choice for children older than 8 years of age.2 Currently, for osteoarticular involvement, we prefer to include gentamicin for the first 7–10 days, as the efficacy of this 3-antibiotic regimen has been reported to be 100%, with no relapses.10

Symptoms of brucellosis typically disappear within the first 4–14 days of appropriate treatment. However, complaints can sometimes persist, as in the first case. It is possible that positive HLA-B27 could have played a role in symptom persistence.

Patients should be followed, clinically and serologically, for at least 2 years, as relapses are relatively frequent.1,7 Moreover, in osteoarticular brucellosis, a focal form of disease, severity is greater and chances of relapse are higher, also resulting in prolonged therapeutic courses and functional sequelae.1,3 Early diagnosis and aggressive treatment are important to avoid sequelae, and although the second case was diagnosed later, both of our cases fully recovered.


1. Eduard Y.Brucellosis. Feigin RD, Cherry JD, eds. In: Textbook of Pediatric Infectious Diseases. 8th ed. Elsevier20181156–1159
2. Bosilkovski M, Dimzova M, Grozdanovski K.Natural history of brucellosis in an endemic region in different time periods. Acta Clin Croat.2009; 48:41–46
3. Pappas G, Papadimitriou P, Akritidis N, et al.The new global map of human brucellosis. Lancet Infect Dis.2006; 6:91–99
4. European Centre for Disease Prevention and Control. Introduction to the Annual Epidemiological Report. In: Annual epidemiological report for 2017.ECDC2017. [cited September 11, 2018]. Available at: Accessed November 18, 2020
5. European Centre for Disease Prevention and Control. The European Union One Health 2018 Zoonoses Report [cited December 12, 2019]. Available at: Accessed November 15, 2020.
6. Pelerito A, Cordeiro R, Matos R, et al. Brucelose humana: análise retrospetiva de casos clínicos suspeitos de infeção entre 2002 e 2013. Boletim Epidemiológico Observações. 2014; 3:19–21
7. Bosilkovski M, Kirova-Urosevic V, Cekovska Z, et al.Osteoarticular involvement in childhood brucellosis: experience with 133 cases in an endemic region. Pediatr Infect Dis J.2013; 32:815–819
8. Uluğ M, Yaman Y, Yapici F, et al.Clinical and laboratory features, complications and treatment outcome of brucellosis in childhood and review of the literature. Turk J Pediatr. 2011; 53:413–424
9. Benjamin B, Annobil SH, Khan MR.Osteoarticular complications of childhood brucellosis: a study of 57 cases in Saudi Arabia. J Pediatr Orthop.1992; 12:801–805
10. Alavi SM, Alavi L.Treatment of brucellosis: a systematic review of studies in recent twenty years. Caspian J Intern Med.2013; 4:636–641
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