CRA53 WHEN IT’S NOT TB: A CASE OF STAPHYLOCOCCUS AUREUS CAVITARY LUNG ABSCESS MIMICKING PULMONARY TUBERCULOSIS

Jacelyn Heng Yi Ting¹, Boon Hau Ng¹, Nor Safiqah Sharil^1,2, Rose Azzlinda Osman¹, Hsueh Jing Low³, Nik Nuratiqah Nik Abeed¹, Andrea Yu-Lin Ban¹

1.      Respiratory Unit, Department of Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Hospital Canselor Tuanku Muhriz, Kuala Lumpur, Malaysia.
2.      Department of Anesthesiology and Critical Care, Faculty of Medicine, Universiti Kebangsaan Malaysia, Hospital Canselor Tuanku Muhriz, Kuala Lumpur, Malaysia.
3.      Internal Medical Unit, Faculty of Medicine and Health Science, Universiti Sains Islam Malaysia, Nilai, Negeri Sembilan.

Introduction
Staphylococcus aureus pulmonary abscess is a rare but serious condition that can closely resemble pulmonary tuberculosis due to overlapping clinical and radiological features. Misdiagnosis can delay appropriate treatment and lead to significant morbidity. We report a case of a young woman presenting with a cavitary lung lesion initially suspected to be TB, later confirmed to be due to methicillin-sensitive Staphylococcus aureus (MSSA) infection.

Case Report
A 40-year-old woman presented with a two-week history of cough, fever, and right-sided chest pain. Lung auscultation revealed crepitation in the right upper lung zone and localised crepitus on palpation. Laboratory investigations showed leukocytosis (white cell count: 14 × 10⁹/L), elevated C-reactive protein (CRP: 256 mg/L), and an erythrocyte sedimentation rate (ESR: 106 mm/hr). Chest radiography revealed a large, thick-walled cavity with an air-fluid level in the right upper zone (Figure 1A). Empirical antibiotic therapy with amoxicillin-clavulanate was initiated. Sputum tests for Mycobacterium tuberculosis and bacterial cultures were negative. Computed tomography of the chest confirmed a large thick-walled cavitary lesion (8.1 x 5.9 x 6.7 cm) with intracavitary fluid collection in the right upper lobe and chest wall extension (Figure 1 B&C). Flexible bronchoscopy revealed an inflamed right upper lobe bronchus with thick mucus secretions. Bronchoalveolar lavage culture grew MSSA. Antibiotic therapy was adjusted to intravenous cefazolin, resulting in significant clinical and radiological improvement.

Discussion
This case highlights the diagnostic challenge of differentiating between Staphylococcus aureus pulmonary abscess and tuberculosis, as both conditions can present with similar clinical symptoms and radiological findings. Bronchoscopy and microbiological analysis played a crucial role in establishing the correct diagnosis. Prompt identification and targeted antibiotic therapy are essential for favourable outcomes. Clinicians should maintain a high index of suspicion for bacterial lung abscesses in patients with cavitary lung lesions, even when tuberculosis is initially suspected.