Case 527 -- A 23 year-old man with left knee pain

Contributed by Deborah Marks-Jones, MD, Ibrahim Batal MD, and William Pasculle, Sc.D

PATIENT HISTORY:

The patient is a 23 year-old male who was diagnosed with Wegner's granulomatosis and renal failure previously. The patient was being treated with Cytoxan and corticosteroids. Four months later, the patient developed a lung infection and was started on trimethoprim-sulfamethoxazole. He underwent a video-assisted thoracoscopy to drain a left pleural effusion. Shortly thereafter, he developed pain in his left knee. The patient underwent debridement of the left knee and a sample of synovial fluid was sent to the UPMC Microbiology lab for Gram stain and culture. A picture of the Gram stain is shown in figure 1. Cultures grew the same organism. The patient continued with antibiotic treatment at an outside hospital.

The patient's knee pain continued and spread to the leg. He was transferred to UPMC Presbyterian hospital for further treatment. On admission to UPMC, the patient was afebrile with a white blood cell count of 11.4 x 109 cells per Liter. He showed mild renal insufficiency with a creatinine of 1.5 mg/dL. Physical exam revealed a wound on the left knee with necrotic debris in the incision. A sample of tissue from the left knee was sent for culture. The culture grew the same organism from April, as well as Pseudomonas aeruginosa. The susceptibilities of the first organism are shown in Table 1.

Table 1. Antibiotic susceptibilities.

Susceptibilities
Kanamycin	Resistant
Amikacin	Sensitive
Tobramycin	Resistant
Gentamicin	Resistant
Sulfisoxazole	Sensitive
Doxycycline	Resistant
Sulfa/Trimethoprim	Sensitive
Sulfamethoxazole	Sensitive
Augmentin	Resistant
Imipenem	Sensitive
Ciprofloxacin	Resistant
Minocycline	Intermediate
Ceftriaxone	Resistant
Clarithromycin	Sensitive
Meropenem	Sensitive

Additional workup included x-rays of the left knee and leg, which showed advanced tibiofemoral joint space narrowing, but no effusion. Because the patient had a history of lung infection, a CT-scan of the chest was also performed (Figures 2 and 3). Two pleural-based nodular opacities were noted in the left lung, along with a small amount of pleural fluid. Several small peripheral nodules were present in the right lung. The differential diagnosis of these findings included Wegener's granulomatosis and infection. A brain MRI was performed and an area of enhancement with surrounding edema was present in the posterior right temporal lobe (Figure 4). The patient continued treatment with trimethoprim-sulfamethoxazole and ceftriaxone was added.

The patient has undergone multiple debridements of the left knee and has undergone a brain biopsy. The patient has been hospitalized for over almost two months while receiving antibiotics. His brain, lung and soft tissue infections remain relatively unchanged.

FINAL DIAGNOSIS