Title : Nocardiosis: an elusive, “insidious” infection: A case report of disseminated nocardiosis with concurrent bloodstream infection
Abstract:
The purpose of this submission is to present a case report of a patient with disseminated nocardiosis and myasthenia gravis.
A 69-year-old male patient presented to the Emergency Department of our hospital with a several-day history of right upper leg swelling and tenderness. His medical history was notable for Myasthenia Gravis, a recent mechanical mitral valve replacement, atrial fibrillation and arterial hypertension.
Physical examination revealed a swollen right thigh with erythema and tenderness, as well as two painful lumps on the left arm and right anterior thoracic wall. Blood sample analysis showed markedly elevated inflammatory markers (WBC: 24.300/μL, CRP: 23mg/dL, ESR: 80mm/h). Opacities in the right lung apex were also demonstrated on chest X-ray. A soft tissue ultrasound was performed, which revealed an intramuscular fluid collection, measuring 2.5 x 10 cm, on the inner side of the right thigh. He was initially started on empiric broad-spectrum antimicrobial therapy with piperacillin/tazobactam and daptomycin pending further work-up. A diagnostic percutaneous aspiration of the abscesses in the right thigh and left arm was performed. Both specimen cultures yielded a Nocardia cyriacigeorgica strain, as did two sets of blood cultures, drawn prior to antibiotic administration.
On that account, the patient was initiated on a combination therapy of trimethoprim/sulfamethoxazole (400/80mg t.i.d.) and imipenem/cilastatin. For further evaluation, he underwent a full-body CT scan that demonstrated, among the known lesions in soft tissues, two ring-enhancing cystic lesions, 5.6mm and 9.5mm, located in the pons and midbrain, respectively, findings suggestive of CNS abscesses. Several nodular lesions, the largest measuring 3.3cm, were also demonstrated in the right upper lobe and were assessed as possible sites of the disseminated nocardiosis.
Nocardiae are a gram positive aerobic opportunistic pathogen. It affects fewer than one person per 100.000 a year and it usually concerns immunosuppressed patients or patients with structural lung diseases. Clinically, most common symptoms involve the respiratory system and the soft tissue abscesses. The gold standard for diagnosis is sequencing species specific genetic sequences after nocardiae have been successfully isolated from a clinical sample. Finally, treatment is based on a combination of two antibiotics with trimethoprim/sulfamethoxazole usually being one of them.
Even though nocardiae are an uncommon pathogen they should be includedin our differential diagnosis. Especially considering that the general population is growing older and the percentage of immunocompromised patients is constantly increasing.
