Chronic Lung Sepsis Dr. Arun Nair

Includes Lung Abscess Empyema Bronchiectasis

Lung Abscess

Lung Abscess

Definition & overview Cavitating, infected, necrotic lesion of lung parenchyma Several possible causes Single or Multiple Small <2cm or large Most secondary to aspiration of oropharyngeal secretions Mixed growth of organisms, including anaerobes

Causes Aspiration Bronchial obstruction {Tumour / Foreign Body} Pneumonia Blood borne infection Transdiaphragmatic spread

Differential Diagnosis Cavitating tumour Infected bronchial cyst/bulla Localised saccular bronchiectasis Aspergilloma Wegeners granulomatosis Hydatid cyst Gas-fluid level in oesophagus, stomach or bowel

Microbiology Anaerobes: Peptostreptococcus, Prevotella, Bacteroides spp (usually not B. fragilis), and Fusobacterium spp. Staph Aureus, Klebsiella, Strep Milleri Strep Pneumonia, gram negative bacilli M.Tuberculosis Fungi

Clinical Features Most patients present over several weeks Malaise, weight loss, fever Cough with copious purulent sputum Can be associated with haemoptysis Toxic features prominent in patients with pneumonia or blood borne infection Clubbing often seen

Investigations CXR: PA & Lateral CT Thorax Sputum & Blood Cultures FBC, CRP, ESR, Serological tests

Treatment AUGMENTIN AMOXIXCILLIN & METRONIDAZOLE CLINDAMYCIN Physiotherapy & postural drainage Trans Thoracic/ endoscopic drainage for large abscess Duration of ABx: 3- 4 weeks

Empyema Pus in pleural space Sequelae of a complicated parapneumonic infection, when bacteria invade pleural space Uncomplicated Complicated Frank Empyema

Pathogenesis Uncomplicated parapneumonic effusion — occurs when the lung interstitial fluid increases during pneumonia, and is characterized by "exudative" pleural fluid chemistries and an influx of neutrophils into the pleural space. resolve with resolution of the pneumonia.

Complicated Parapneumonic effusion occurs when there is persistent bacterial invasion of the pleural space. Results in pleural fluid acidosis (anaerobic utilization). Lysis of neutrophils increases the LDH concentration in the pleural fluid to values often in excess of 1000 IU/L. Complicated parapneumonic effusions are often sterile because bacteria can be cleared rapidly from the pleural space. (Loculation )

Thoracic Empyema Formation of empyema is the third stage and is characterized by bacterial organisms seen on gram stain or the aspiration of pus on thoracentesis. A positive culture is not required for diagnosis.

Bacteriology Mixed bacterial flora Anaerobic bacteria in 36-76% Streptococcus milleri, Staphylococcus aureus, and Enterobacteriaceae. Patients with diabetes mellitus are at increased risk of empyema secondary to Klebsiella pneumoniae. S. pneumoniae and S. aureus (including methicillin-resistant organisms) are the leading causative bacteria in children with empyema.

Pleural fluid analysis Pus Ph <7.2 Glucose < 60 mg/dl LDH>1000 IU/L WBC>15/nl

Imaging CXR CT USG

Signs favouring empyema Evidence of lung compression Smooth margins Blunt angle with chest wall Dissection of thickened visceral and parietal pleura

Treatment Pleural drainage Chest Drain Thoracoscopy Antibiotics Fibrinolytics: No convincing benefit

Bronchiectasis Abnormal permanent dilatation of one or more bronchi Poor mucous clearance Chronic bacterial infection & inflammation Long term lung damage

Types Saccular /Cystic Cylindrical Varicose

Saccular Bronchiectasis Large baloon like dilatation from severe loss of bronchial wall Assoc with severe lung infections, large sputum volumes, finger clubbing

Cylindrical Bronchiectasis

Varicose Bronchiectasis

Causes Congenital {defective bronch wall/ sequesteration} Post infective {TB, Pertussis, NTM, ABPA} Airway obstruction (eg, foreign body aspiration) Defective host defenses{ CVID, HIV, phagaocyte dysfn Inflammatory pneumonitis {gastric aspiration, toxic gas inhalation} Abnormal mucociliary clearance {Primary Ciliary Dyskinesia, cystic fibrosis, Young's syndrome Rheumatic and systemic diseases, cigarette smoking, Chronic Bronchitis.

Symptoms Cough (98 percent of patients) Daily sputum production (78 percent) Dyspnoea (62 percent), Rhinosinusitis (73 percent) Hemoptysis (27 percent) and recurrent pleurisy (20 percent).

Physical Findings Crackles (75 percent) Wheezing (22 percent) were common, Digital clubbing occurred in only 2 percent of patients.

Pathophysiology Induction of bronchiectasis requires two factors An infectious insult Impaired drainage, airway obstruction, or a defect in host defense Recurrent infection leads to further scarring, obstruction, and distortion of the airways, as well as temporary or permanent damage to the lung parenchyma.

Diagnostic workup The following LAB studies should be part of the initial evaluation of a patient with bronchiectasis: A complete blood count with differential Immunoglobulin quantitation to measure the levels of the immunoglobulins IgG, IgM, and IgA Sputum culture and smear for bacteria, mycobacteria, and fungi

Imaging CXR radiographic findings include linear atelectasis, dilated and thickened airways (ie, tram or parallel lines, ring shadows on cross section) and irregular peripheral opacities that may represent mucopurulent plugs.

High Resolution CT Thorax Airway dilatation Bronchial wall thickening Lack of tapering mucopurulent plugs or debris accompanied by post-obstructive air trapping (tree-in-bud)

Distribution A central (perihilar) distribution is suggestive of ABPA. predominant upper lobe distribution is characteristic of cystic fibrosis middle and lower lobe distribution is consistent with PCD lower lobe involvement is typical of idiopathic bronchiectasi

Spirometry Obstructive picture common Frequently isolated pathogens on CULTURE include Hemophilus influenzae, Pseudomonas aeruginosa (especially mucoid types), and, less frequently, Streptococcus pneumoniae

Treatment Postural drainage Based on sputum culture & sensitivity Non-Pseudomonas organism: Amoxicillin: 1gm TID 14 days Augmentin 625 mg TID 14 days Doxycyline 100mg BD 14 days Ciprofloxacin 750 mg BD 14 days (Pseudomonas) Ceftazidime 2gm TID 7-14 days (Pseudomonas) Nebulised Tobramycin (Pseudomonas)

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Signs favouring lung abscess Spherical shape with irregular and thick wall Absence of lung compression Sharp angle with chest wall Vasculature around abscess