Pulmonary Nocardiosis in an Immunocompetent Individual by Nocardia otitidiscaviarum: Case Report

Ultrasound-guided drainage of the abscess yielded dry, chalky white colonies of Nocardia species within 24 hours (Fig. 5).Gram staining showed gram-positive branching filamentous bacteria (Fig. 6).MALDI-TOF MS identified the isolate as Nocardia otitidiscaviarum.Antimicrobial susceptibility testing (AST) was performed using the broth microdilution method in accordance with Clinical and Laboratory Standards Institute (CLSI) M24 recommendations.5 The isolate was susceptible to cotrimoxazole, imipenem, and linezolid, but resistant to ceftriaxone.The patient received supportive care, including inotropic and ventilatory support.Trimethoprim-sulfamethoxazole (10 mg/kg/day of trimethoprim component in two divided doses) was initiated, and ceftriaxone was discontinued.The patient's condition initially improved but later deteriorated, requiring invasive mechanical ventilation.Antibiotics were escalated to linezolid (600 mg IV every 12 hours), but the patient died due to septic shock, likely due to the delayed presentation and rapid disease progression. IntroductIonNocardiosis is an opportunistic infection caused by aerobic actinomycetes.It predominantly affects immunocompromised individuals, but can also occur in those without predisposing conditions. 1 Inhalation of contaminated dust is a common route of infection.While Nocardia asteroides complex is frequently implicated, other species, including Nocardia otitidiscaviarum, can cause disease. 2 Nocardia otitidiscaviarum is an environmental organism less frequently associated with human infections.3 This case report describes a pulmonary infection caused by Nocardia otitidiscaviarum in an immunocompetent worker, emphasizing the clinical challenges and the importance of early diagnosis.4 case descrIptIonA man in his early 40s, a blasting well worker with no known comorbidities, presented to the emergency department with a month-long history of cough with yellow expectoration and breathlessness, and a 15-day history of high-grade fever.His occupation as a blasting well worker was a relevant factor, given Nocardia's prevalence in soil.On examination, the patient was well-built and nourished, with a BMI of 22.5 kg/m².He exhibited tachycardia, tachypnea, and oxygen saturation of 76% on room air.Noninvasive mechanical ventilation was initiated.Respiratory examination revealed bilateral crepitations and bronchial breath sounds on the left side.Other systemic examinations were unremarkable.Empirical antibiotics (ceftriaxone 1 gm IV every 12 hours and azithromycin 500 mg orally once daily) were started.Blood tests showed a high total leukocyte count (51,100/µL), and arterial blood gas indicated type I hypoxic respiratory failure.The patient was HIV-negative.Chest radiographs showed bilateral lower-zone opacities, which rapidly progressed over 4 days (Figs 1 and 2).A CT scan revealed a large consolidation with an abscess in the left lower lobe and diffuse ground-glass opacities (Figs 3 and 4).