{'fraction_non_alphanumeric': 0.037943696450428395, 'fraction_numerical': 0.02447980416156671, 'mean_word_length': 5.627027027027027, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 1, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Rare Klebsiella pneumoniae anterior mediastinal abscess masquerading as cardiac tamponade.

Dear Editor, Mediastinal abscess, an uncommon medical condition caused by remote source of infection, rarely occurs in the absence of trauma or instrumentation. Acute pericarditis with cardiac tamponade, associated with a mediastinal abscess, is a rare clinical presentation; if left untreated, it is potentially fatal. We present a case that encompassed the rare association of a primary gram-negative mediastinal infection, with a reactive pericardial effusion, presenting as pericardial tamponade. The approach to extra-cardiac structure evaluation and the importance of initial wide-sector width image acquisition are detailed in this report. A 29-year-old man, with medical history of obesity and type 2 diabetes mellitus (glycated haemoglobin/ Hba1C 10.5%), presented to the emergency department with a 2-week history of substernal pleuritic chest pain and dyspnea. He was febrile on presentation (temperature 38.4°C), tachycardic (heart rate 112 beats/minute) and hypotensive (blood pressure 89/67mmHg) though saturating normally on room air. Clinical examination revealed muffled heart sounds with jugular venous distension. Significant laboratory findings included leukocytosis (white cell count 15.17x109/L) with neutrophilia, elevated C-reactive protein of 188mg/L and hyperlactatemia of 3.2mmol/L. Blood culture showed no bacteria growth, and retroviral screen was negative. Electrocardiogram demonstrated widespread ST elevations and PR depression, suggestive of pericarditis. Initial chest radiograph revealed a wide mediastinum (Fig. 1). Echocardiographic substernal view showed a large pericardial effusion measuring 2.9cm adjacent to the right heart, with right ventricular diastolic collapse. The suspected echogenic structure is seen anterior to the right ventricle. It was initially described as epicardial fat (Fig. 2A). The clinical diagnosis was acute pericarditis complicated by cardiac tamponade. Urgent pericardiocentesis was done and 410mL of haemoserous fluid was aspirated. Analysis of the pericardial fluid revealed neutrophilic predominance, elevated lactate dehydrogenase, protein, and adeno-deaminase (ADA). It was negative for bacteriology, acid-fast bacilli staining and malignant cells. He was started on high-dose ibuprofen and colchicine. Ann Acad Med Singap 2021;50:655-6 https://doi.org/10.47102/annals-acadmedsg.202143