Two cases of Nocardia bacteraemia in solid organ transplant recipients

Caser Report: A Rare Case of Pulmonary Nocardiosis Caused by Nocardia pseudobrasiliensis After Liver Transplantation

Nocardia is a gram-positive bacillus with the microscopic appearance of branching hyphae and is mainly distributed in the soil. Nocardiosis more frequently occurs in immunosuppressed patients. Since nocardiosis has a high mortality rate, immediate diagnosis and treatment are needed. We report the first case of pulmonary nocardiosis caused by Nocardia pseudobrasiliensis after liver transplantation. A 58-year-old woman underwent living-donor transplantation for primary biliary cholangitis. Seven months after transplantation, she came to our hospital complaining of fever and anorexia. Computed tomography of the lungs showed a 45 mm large nodule affecting the upper lobe of the left lung. We started administering empiric antibiotics and tapering immunosuppression, but the patient's condition gradually worsened, and lung lesions increased. On the fifth day after hospitalization, bacteria developed from sputum cultures were identified as N. pseudobrasiliensis by matrix-assisted laser desorption ionization time of flight mass spectrometry. We started treatment with trimethoprim-sulfamethoxazole. The patient's clinical symptoms and laboratory data improved quickly. After one month of hospitalization, this patient was discharged. Then, the lung lesion almost vanished. Ten years after her transplant, the patient is alive with a well-functioning graft.

Bacteremia caused by Nocardia farcinica: a case report and literature review

BACKGROUND

Nocardia farcinica is one of the most common Nocardia species causing human infections. It is an opportunistic pathogen that often infects people with compromised immune systems. It could invade human body through respiratory tract or skin wounds, cause local infection, and affect other organs via hematogenous dissemination. However, N. farcinica-caused bacteremia is uncommon. In this study, we report a case of bacteremia caused by N. farcinica in China.

CASE PRESENTATION

An 80-year-old woman was admitted to Peking Union Medical College Hospital with recurrent fever, right abdominal pain for one and a half month, and right adrenal gland occupation. N. farcinica was identified as the causative pathogen using blood culture and plasma metagenomics next-generation sequencing (mNGS). The clinical considerations included bacteremia and adrenal gland abscess caused by Nocardia infection. As the patient was allergic to sulfanilamide, imipenem/cilastatin and linezolid were empirically administered. Unfortunately, the patient eventually died less than a month after the initiation of anti-infection treatment.

CONCLUSION

N. farcinica bacteremia is rare and its clinical manifestations are not specific. Its diagnosis depends on etiological examination, which can be confirmed using techniques such as Sanger sequencing and mNGS. In this report, we have reviewed cases of Nocardia bloodstream infection reported in the past decade, hoping to improve clinicians' understanding of Nocardia bloodstream infection and help in its early diagnosis and timely treatment.

Cryptogenic Organizing Pneumonia Complicated With Cutaneous Disseminated Nocardia Infection: A Case Report and Literature Review

Nocardia disease is a rare opportunistic infection that usually occurs in individuals with solid organ transplantation, malignant tumors, human immunodeficiency virus (HIV) infection, or chronic lung disease history. Here, we reported a rare case of cryptogenic organizing pneumonia (COP) combined with disseminated Nocardia infection. A 75-year-old man was admitted to the respiratory department due to weakness and poor appetite for 3 months. The chest CT scan showed dense patchy shadows in the dorsal lower lobe of both lungs. After the transbronchial lung biopsy, the histopathological findings supported the diagnosis of COP. During the period of glucocorticoid reduction (oral methylprednisolone tablets 24 mg one time a day), the patient presented with masses on the back and bilateral upper limbs and intermittent fever for 3 days. After admission, the patient underwent a series of examinations and an ultrasound puncture of the mass. The puncture fluid was caseous necrosis, which was confirmed to be Nocardia infection after bacterial culture, so the diagnosis was disseminated Nocardia infection. After 13 days of admission, the patient developed a headache, accompanied by decreased visual acuity and blurred vision. An imaging (enhanced brain CT) examination revealed intracranial space-occupying lesions. The neurosurgeon was consulted and performed transcranial abscess puncture and drainage, intravenous antibiotics (meropenem, etc.) for 2 months, and trimethoprim/sulfamethoxazole (TMP-SMX) for 6 months. The patient was followed up for 3 years and has remained relapse-free. The mortality rate of disseminated Nocardia infection is as high as 85%, especially when combined with brain abscesses. Therefore, timely diagnosis and correct treatment are crucial for the prevention of fatal consequences. The report of this case can enable more patients to receive early diagnosis and effective treatment, so as to obtain a satisfied prognosis.