A 30-year-old male laborer with no significant past medical history presented to our hospital October 2016 with chronic sinus discharge from his left thigh. He mentioned that his problem started two months ago when he started complaining of pain in his left thigh, associated with swelling, redness and hotness, and noticed a small boil with intermittent serous discharge at his thigh, which was diagnosed as a subcutaneous abscess by a general practitioner, that was treated in a primary health care center with local drainage and multiple short courses of antibiotics (Cloxacillin 500 mg TID for 14 days, then Ciprofloxacin 500 mg BID for another 14 days) with no benefit. The drainage was not sent for culture by the treating physician. During this period, the patient's pain used to improve temporarily after each drainage, however, after few days, the pain and local symptoms recur. Therefore, he kept visiting the emergency department with tender indurated skin at the posterior aspect of the thigh, where an Ultrasound was performed showing a 10 cm homogenous anechoic collection, with surrounding subcutaneous edema. Again, a needle aspiration was attempted, but no pus came out. And for two months the patient kept suffering until he was referred to orthopedics service in our institution.
At presentation, the patient was afebrile with no constitutional symptoms and with chronic sinus discharge at the posterior aspect of his left thigh (Fig. 1). Initial lab investigations were normal with normal inflammatory markers; WBC = 9.3*10^3/ul, ESR = 21 mm/hr, CRP < 5 mg/dl. Left femur radiographs and MRI showed features of chronic osteomyelitis with sinus tract communicating with skin at the posterior thigh type II-A according to Cierny-Mader classification of osteomyelitis (superficial osteomyelitis in a normal host) (Fig. 2, Fig. 3, Fig. 4). Swab from the discharge was taken for gram stain and culture, and the patient was started on cefazolin empirically. Quantiferon test for TB was negative, and serology tests for Malaria, Brucella, Salmonella, Aspergillus, and CMV were negative.
Several days later, the Gram-stained smear of colonies revealed gram-negative coccobacilli. The isolate was oxidase positive and did not oxidize glucose. Following 16S ribosomal RNA sequencing identified the organism as Moraxella oselensis. And as in-vitro susceptibility testing for this organism is not routinely done in our hospital, the patient continued Cefazolin 1 g TID for another ten days. Then antibiotic was changed to intravenous Ampicillin-Sulbactam every 6 h, and posted for bone debridement and biopsy as recommended by ID team as sinus discharge did not stop.
Sinogram showed two sinus tracts, one is superior and another one is inferior, with no contrast connected to the intramedullary cavity of the femur (Fig. 5). A 3 cm skin incision, and excision of the upper sinus tract and curettage for the lower tract were done. Afterwards, drilling for the two bony sinuses in the femur was performed, no intramedullary pus was appreciated. Bone biopsy was sent for culture and histopathology. The tissues were washed with copious amount of normal saline, and Vacuum dressing was applied.
The surgical pathology specimen culture report was ready after 7 days post-operatively, which showed no growth; this might be explained as the patient had already been on antibiotics for around 16 days (Cefazolin for 10 days, and Ampicillin-Sulbactam for 6 days). Manual sensitivity for Moraxella oseolensis from the previous specimen was tested and showed it was very sensitive to Amoxicillin, Ceftriaxone, and Trimethoprim-Sulphamethoxazole.
Post-operatively, the patient was started on intravenous Ceftriaxone and Vacuum dressing was changed every 3 days, with only minimal serosanguinous collection. After seven days, the wound became dry, the Vacuum dressing was removed, sterile dressing was applied, and the patient was discharged home on daily intravenous 2 g Ceftriaxone to be given in a special clinic for outpatient intravenous drugs administration, to complete a total duration of six weeks of treatment.
The patient sinus discharge stopped, and complete wound healing was observed and documented on his visit to the outpatient clinic after 21 days post-operatively. He was followed up clinically for more than 3 months, the inflammatory markers maintained their normal range values during the post-operative period (WBC = 8.8*10^3/ul, ESR = 6 mm/hr, CRP <5 mg/dl), and the patient stayed asymptomatic during this period.