Lower Respiratory Infections PDF

Lower Respiratory Infections Pneumonia • Infection causing inflammation to lung parenchyma o Bacterial o Fungal o Viral • Transmission: o Most common: coughing and sneezing droplet transmission o Fomite transmission: contaminated surfaces o Aspiration of infecting agent • Risk Factors: o Immunocompr...

Lower Respiratory Infections Pneumonia • Infection causing inflammation to lung parenchyma o Bacterial o Fungal o Viral • Transmission: o Most common: coughing and sneezing droplet transmission o Fomite transmission: contaminated surfaces o Aspiration of infecting agent • Risk Factors: o Immunocompromised o Cystic fibrosis o Elderly and immunocompromised o Cigarette smoking Bacterial Pneumonia (bronchopneumonia): • Occurs when: o Host systemic resistance is reduced o Microbes overwhelm defense systems o Cause rust colored sputum that appears consolidated on x-rays indicating disease • Labs: o CBC (high WBC) o CRP high o Sputum gram stain o Sputum culture o Blood culture o Urine antigen test: high sensitivity and specific (S. pneumoniae; Legionella pneumophilia; Histoplasma capsulatum) • Imaging: alveolar contains lobar and patchy distribution; bilateral infiltrates • Classification of Bronchopneumonia (bacterial) o Community acquired pneumonia (CAP): from normal, everyday environment § Streptococcus pneumoniae § Mycoplasma pneumoniae § Haemophilus influenza § Moraxella catarrhalis § Chlamydia pneumoniae o Hospital acquired pneumonia (HAP): acquired > 48hrs after hospital admission *severe than others* § Institution dependent § Pseudomonas aeruginosa § Methicillin-sensitive Staph. Aureus § Methicillin-resistant Staph. Aureus (MRSA) o Health care associated pneumonia (HCAP): by attending hospitals or hemodialysis clinic § Methicillin-resistant Staph. aureus (MRSA) § Pseudomonas aeruginosa • Treatment/Prevention: Can be prevented w vaccine, good hand hygiene, healthy lifestyle o Pneumonia Vaccine: § Pneumococcal conjugate vaccine (PCV, Prevnar) § Pneumococcal polysaccharide vaccine (Pneumovax) § Hib vaccine § RSV vaccine (Palivizumab (Synagis) Type • Lobar pneumonia • Bronchopneumonia • Interstitial pneumonia • • • • • • • • • • • • • Organisms S. pneumoniae (most common) Legionella Klebsiella S. pneumoniae Klebsiella S. aureaus H influenza Legionella Mycoplasma Chlamydiphila pneumoniaem Chlamydophila psittaci Coxiella burnetiid Viruses Characteristics • On entire lobe • Acute inflammatory infiltrates from bronchioles into adjacent alveoli • Diffuse patchy inflammation Aspiration Pneumonia • Aspiration of gastric contents into respiratory tract o Occurs in: § the highly debilitated § Unconscious patients § pts w repeated vomiting episodes § pts w abnormal gag § Swallow reflexes § Most common cause of death in stroke patients o Partly chemical pneumonia from gastric acid o Partly bacterial pneumonia from oral flora (>1 microbes, aerobes more common) o Common complication: lung abscess o Microaspiration occurs in people with GERD Lung Abscess (most common) • Localized pus collection in parenchyma • Common causes: o Aspiration of oropharyngeal contents o Antecedent primary lung infection (S. aureus, K. pneumoniae, and type 3 pneumococcus) o Septic Emboli (Infective bacterial endocarditis and Dental procedures) • Most common in R lung • Signs/Symptoms: o Bloody sputum Influenza • Most recent outbreak: H1N1/09 in 2009 • Occurs when new strain of influenza virus transmitted from animals to humans • Caused by Type A influenza strains • Transmission: o Droplets o Contaminated hands and fomites o In crowded environments o 1-4 day incubation*** • Pathophysiology: o Binds to epithelial cells (specifically sialic acid) o Can cause acute lung injury and lead to pneumonia • Symptoms range from mild to severe, depending on strain, age, co-morbidities • Strains of Flu o Flu A (severe): Found in humans, animals, and birds § Characterized by 2 proteins on virus surface: Hemagglutinin (H) and neuraminidase (N) § Only type to have produced pandemics o Flu B: Found only in humans; less severe than type A o Flu C (mild): Found only in humans KNOW NAME OF PROTEINS AND WEHRE THEY ARE FOUND • Diagnostic Testing o Rapid influenza molecular assays o Rapid influenza antigen detection test (RIDT) o Reverse transcription polymerase chain-reaction (RT-PCR) o Viral culture to find strain o Imaging (x-rays, CT scan): differentiate flu from Pneumonia • Prevention o Vaccine: Quadravalent (4-type) Vaccine containing 2 most common subtypes (A and B) influenza viruses Bronchiectasis • Destruction of SM and elastic tissue leading to permanent dilation of bronchi and bronchioles • A chronic obstructive pulmonary disease (along with emphysema, asthma, and chronic bronchitis) • Defect in mucociliary transport and foul smelling, bloody thick sputum • Most common in cystic fibrosis pts • Signs and symptoms: o Thick bloody sputum o Clubbing fingers • Imaging o Chest X-ray: “tram tracks” parallel line opacities o CT scan (high resolution): “Signet ring” sign – dilated airway lying next to pulmonary artery • Treatment o Antibiotic against P. aeruginosa and H. influenza o Anti-inflammatory: systematic and inhaled glucocorticoids