Emphysematous osteomyelitis caused by Salmonella typhi in beta thalassemia major.

There have been various cases of salmonella osteomyelitis reported in sickle cell anemia. We present a case of emphysematous osteomyelitis caused by Salmonella typhi in a 29-year-old beta thalassemia major patient. Diagnosis of emphysematous osteomyelitis was confirmed by computed tomography and magnetic resonance imaging, and culture of pus drained during surgical debridement confirmed the causative microorganism, Salmonella typhi. Antimicrobials were given according to microbiological sensitivity for a period of 8 weeks. Our patient also received hyperbaric oxygen therapy. At the end of therapy, he was afebrile and laboratory parameters normalized with a residual joint deformity which developed within 3 months.

Introduction

Emphysematous osteomyelitis is a rare but a potentially fatal condition that must be considered whenever intraosseous gas is identified on imaging. The organisms implicated in most cases of emphysematous osteomyelitis are anaerobes or members of Enterobacteriaceae family.[1] The association of salmonella osteomyelitis with sickle cell anaemia is well established.[2] To the best of the author's knowledge, there has been only one case of recurrent salmonella osteomyelitis in a beta thalassemia trait reported in literature.[3] We present a unique case of emphysematous osteomyelitis caused by Salmonella typhi in a beta thalassemia major.

Case History

A 29-year-old male, known case of beta thalassemia major, presented with pain in left hip joint associated with limitation of movement since 5 days and fever since 3 days. At 12 years of age, the patient underwent splenectomy due to increased blood transfusion requirements. Vitals were stable except for a body temperature of 102°F. On physical examination, restricted and painful passive and active movements along the left hip joint were noted. A complete blood count (CBC) was done revealing total leucocyte count (TLC) of 28,320/mm3 with 54.3% neutrophils, erythrocyte sedimentation rate (ESR) of 120 mm at the end of 1 h, C-reactive protein (CRP) of 68.9 mg/L, and blood culture grew non-lactose fermenting colonies on MacConkey agar and agglutination with salmonella polyvalent O antisera suggested Salmonella species. Further agglutination with Salmonella Factor 09 antisera was done, which was positive and was confirmed to be Salmonella typhi. Apart from this, manual test for biochemicals of peptone water for Indole, Triple Sugar Iron (TSI), urea hydrolysis, and cirate utilisation also suggested Salmonella species. Antimicrobial susceptibility testing done by VITEK 2 showed pansensitive to most antibiotics except partial resistance to quinolones. Stool and urine culture were also done to determine the carrier status in this patient, but turned out to be negative for Salmonella.

Radiograph was suggestive of air in the head and proximal shaft of left femur [Figure 1]. Computed tomography (CT) scan confirmed the presence of air pockets in the head and shaft of left femur and left iliacus muscle. In magnetic resonance imaging (MRI), altered signal intensity areas were seen in the left femur neck and upper two-third of shaft with signal voids within suggestive of air specks. There were hyperintensities on T2-weighted and on short tau inversion recovery (STIR) sequences. A focal breach in the cortex of femoral neck was identified posteriorly near the lesser trochanter. Altered signal intensity was noted in left iliacus, obturators, and gluteus and vastus lateralis suggestive of myositis [Figure 2].

Figure 1

Radiograph of left hip, posteroanterior view showing intra-osseous gas in head and proximal shaft of left femur (white arrow)

Figure 2

(a) Coronal CT scan showing hypodense foci (white arrow) representing air within the left femur, (b) Coronal short tau inversion recovery (STIR) showing hyperintensities (white arrow) in left femoral head, neck and shaft with signal void areas within. Similar altered signal intensity seen in left iliacus (white dashed arrow) and obturator externus suggestive of myositis. (c) Axial T2-weighted fat saturation showing cortical breach along the posterior portion of femoral neck (white arrow). (d) Coronal T1-weighted reveals altered signal intensity areas involving the left femur (white dashed arrow). (e) Coronal post contrast T1-weighted fat saturation showing slight post contrast enhancement (white arrow). (f) Axial post contrast T1-weighted showing similar finding (white dashed arrow)

The patient was treated with intravenous amikacin and cefuroxime, and left hip exploration was done under general anaesthesia. Black colored pus was drained and sent for culture and sensitivity which turned out to be Salmonella typhi. After surgical exploration, a drain was placed in the bone window created for drainage of pus and discharge. On discharge, he was started on oral amoxicillin–clavulanic acid for 3 weeks.

He was readmitted 20 days later with pain and swelling over left hip and pus discharge from the drain. Complete blood profile showed TLC of 18,430/mm3 with 58.4% neutrophils, ESR 130 mm/h, and CRP of 34.64 mg/L. MRI revealed femoral altered signal intensity, air speckle, and intra marrow collection which had reduced compared to previous MRI. There was also intra marrow fluid collection communicating into intermuscular plane and vastus lateralis forming a thin tract, from intermuscular plane to skin, with mild joint effusion. Re-exploration of left hip was done which revealed pus and necrotic tissue over posterior-lateral head, neck, and proximal diaphysis. Thorough pulsed lavage was done with gentamycin and saline along with betadine and hydrogen peroxide. After discharge, the patient was started on cefixime for 4 weeks and he underwent hyper baric oxygen therapy and physiotherapy. After 4 weeks, the patient continued to remain afebrile. CBC and ESR were within normal limits and X-ray showed a bone window created surgically on the posterio-lateral aspect of proximal left femur and radiolucency due to surgical debridement [Figure 3]. Three months later, he developed left hip joint deformity with restricted movements in the joint.

Figure 3

(a) Post-operative radiograph of left hip and femur, anteroposterior view showing the window created surgically on the posterolateral aspect of proximal left femur (white arrow). (b) Lateral view showing radiolucency due to surgical debridement (white dashed arrow)

Discussion

Intraosseous gas was first described as a sign of osteomyelitis in 1981 by Ram et al.[4] When seen in the extra-axial skeleton, intraosseous gas is virtually pathognomonic for emphysematous osteomyelitis; in rare cases the differential diagnosis includes trauma, post-surgical change, lymphangiomatosis of the bone, degenerative disease, osteonecrosis, and neoplasm.[5] Salmonella causing osteomyelitis is very rare (0.45% of all osteomyelitis), and osteitis is reported in only 0.8% of cases of typhoid fever.[6] The most common mode of spread of Salmonella is hematogenous and the most frequent sites involved are the diaphysis of long bones, mainly the femur and humerus.[7] Salmonella osteomyelitis is a well-recognized infection in persons with sickle cell disease, connective tissue disorders, malignancies, and previous trauma or surgery.[89] In beta thalassemia major, Salmonella infection could be attributed to reduced phagocytic and opsonic activity following splenectomy, iron overload, and decreased CD4/CD8 ratio.[1011]

A preceding history of infection is not usual.[12] Stool cultures indicative of carrier state may or may not be positive.[12] Initial investigations include CBC, inflammatory markers (ESR and CRP), and radiographs followed by MRI. These modalities help identify bone infections.[13] In our patient, CT scan showed hypodense focii in the affected bone confirming the presence of air pockets. Also, MRI T-2 weighted and STIR sequences showed hyperintensities in the affected bone. Blood culture was positive for Salmonella typhi in our case, but positive results have been reported in only 71% of patients with salmonella osteomyelitis.[3]

When emphysematous osteomyelitis is seen, empiric antibiotics with activity against anaerobes and members of Enterobacteriaceae family should ideally be initiated after obtaining sufficient samples from bone for microbiological assay.[3] Ampicillin, chloramphenicol, third-generation cephalosporins, and quinolones have been used.[11] Our patient was started on IV amikacin and cefuroxime and later switched to oral amoxicillin–clavulanic acid on discharge. Most of the studies stated that the most effective therapy of a confirmed salmonella osteomyelitis is a combination of radical operative intervention and targeted intravenous antibiotics sensitive to the organism.[3] Hyperbaric oxygen therapy has also been used as an adjunct.[13]

Conclusion

Emphysematous osteomyelitis caused by Salmonella typhi is a rare infection in beta thalassemia major patients and could be attributed to reduced phagocytic and activity following splenectomy, iron overload, and decreased CD4/CD8 ratio.[1011] Aggressive surgical intervention and appropriate antimicrobial are required as emphysematous osteomyelitis is associated with significant morbidity and mortality.

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The authors certify that appropriate patient consent was obtained.

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Conflicts of interest

There are no conflicts of interest.