Brucella Osteomyelitis of the Calcaneus

To the Editor:

Brucellosis was first described by Hippocrates in 450 BC, and it has been known by many terms, including Malta fever, Mediterranean fever, Gibraltar fever, Cyprus fever, and undulant fever. It is a zoonotic infection of both wild and domestic animals, with virtually all human infections derived from animal sources. Although worldwide in distribution, it is seen most commonly in India, Mexico, Central and South America, and the Mediterranean area. Brucellosis is still an important public health problem throughout the world,[1,2,3] but mainly in the Middle East region, including the southeastern part of Turkey.[4] Although brucellosis often results in complications in various parts of the body, the musculoskeletal system is most commonly affected.[1,2,5] Osteoarticular complications, such as arthralgia and arthritis, are commonly seen in childhood brucellosis. Calcaneal osteomyelitis is a rare form that occurs primarily after puncture wounds.[6,7] The Brucella osteomyelitis in the calcaneus in this case report is a unique form that was confirmed by serology and culture.

Case Report

A 6-year-old girl with right heel pain of 15 days’ duration was referred to our clinic at Harran University in Urfa, Turkey, with a preliminary diagnosis of subtalar arthritis without discharge. The most notable point in the patient’s anamnesis was that she had been consuming fresh cheese. Since then, she had experienced progressively worsening pain in the right heel as well as gait difficulties; she had no history of a puncture wound on the foot. On hospital admission, she was febrile, with a temperature of 38.3°C, and her right heel was moderately swollen and painful but not warm. Other systemic findings and laboratory results, such as complete blood cell count, erythrocyte sedimentation rate, HLA-B27, and purified protein derivative, revealed no abnormalities. Radiographic examination of the right heel showed a round lytic image with well-defined margins localized in the calcaneus. However, technetium-99 methylene diphosphate bone scintigraphic examination revealed calcaneal osteomyelitis. Although Gram’s and Ziehl-Neelsen stains showed no organisms, blood cultures yielded Brucella abortus, and the standard tube agglutination test with Brucella abortus was positive at 1/640 titer. On the basis of these findings, brucellosis was diagnosed, and a combination of rifampin and trimethoprim-sulfamethoxazole was prescribed for 2 months. The patient was followed up for 1 year, during which she had no symptoms and made a complete recovery. The standard tube agglutination titer decreased to 1/320 at 3 months after the start of treatment.

Discussion

To the best of our knowledge, there is only one previous case of Brucella osteomyelitis of the calcaneus reported in the literature.[8] However, this case is not specific for Brucella osteomyelitis. There was a discharge, but Brucella tends to cause nonsuppurative osteomyelitis,[9,10] and the diagnosis depended only on the positive standard tube agglutination titer for Brucella. However, the standard tube agglutination can cross-react with antibodies to the other gram-negative bacilli, such as Francisella tularensis, Vibrio cholerae, and Yersinia enterocolitica serotype 0:9.[11,12]

In Turkey, the incidence of brucellosis has increased in recent years because it could not be completely eradicated among animals in the country, especially sheep and goats.[2] In the southeastern region of Turkey, most people consume unpasteurized dairy products collected from villages. In one study,[13] the most frequent source of infection was fresh white cheese (54.1%). Our patient constituted a typical case of brucellosis in that she lived in the southeastern region of the country. Although brucellosis can occur at any age, it is most commonly seen in adolescents and young adults.[1,5] Both sexes are affected equally.[5,14]

Osteoarticular involvement is mostly seen as a complication of brucellosis, with a prevalence varying from 0% to 37.5%.[1,5,15] In approximately 6% to 8% of affected children, the primary site of osteomyelitis is the calcaneus. The infection may be hematogenous in origin or mostly caused by external inoculation of organisms, such as in puncture wounds. Although Pseudomonas aeruginosa has been the predominant organism responsible for these infections, some others may also have been isolated, such as staphylococci and streptococci.[6,7,16,17,18] Our case is interesting because the patient had calcaneal osteomyelitis caused by an organism other than P aeruginosa.

A radionuclide bone scan with technetium-99 methylene diphosphate was performed when clinical suspicion was high and the radiographic examination results were normal. Bone scintigraphy has proved to be very sensitive in the detection of early lesions in osteoarticular brucellosis.[10,19,20]

We have reported an unusual case of brucellosis with nonsuppurative osteomyelitis in the calcaneus. It was also interesting because there was no predisposing factor for infection in this location. We hope that similar cases of osteomyelitis can be found through careful screening of young adults and children with pain in the extremities in developing countries.