Unformatted text preview: Lower Respiratory Tract Infections Respiratory Tract Infections 1. Acute and chronic bronchitis 2. Bronchiolitis (infection of the tubes) 3. Acute pneumonia 4. Pleural effusion and empyema 5. Lung abscess Acute Pneumonia Infection of the lung parenchyma Commonest cause of infection - related mortality: out-patient setting - mortality 5% out requiring hospitalization - mortality 25% hospital acquired - mortality 32% Acute Pneumonia Early, specific antimicrobial therapy reduces morbidity and mortality Etiology of pneumonia frequently not ascertained No diagnostic test can identify all potential pathogens Acute Pneumonia - Epidemiology Community acquired (CAP) vs hospital/nosocomial (HAP/NAP) hospital/nosocomial [pneumonia developing 48 hrs after admission to hospital] Presence or absence of co-morbid illness co Seasonal presentation Community Acquired Pneumonia Etiologies <65 yrs S. pneumoniae M. pneumoniae Respiratory viruses C. pneumoniae H. influenzae >65 yrs or co-morbid illness S. pneumoniae Respiratory viruses H. influenzae Aerobic Gram-negative bacilli S. aureus Legionella spp. No agent found in 30-50% of cases Hospital Associated Pneumonia - Etiology Aerobic Gram-neg. bacilli 60-80% Gram- neg. 60Anaerobic bacteria 20% S. aureus 11% S. pneumoniae 3% Others (Legionella, viruses, fungi) (Legionella, Acute Pneumonia - Transmission Infectious agents reach lung by: inhalation of aerosilized material aspiration of upper airway flora inapparent ("silent") gross aspiration of gastric contents hematogenous Pathogenesis of Pneumonia
Micro-Organism Microinoculum virulence Lung Defense Mechanisms systemic local Acute Pneumonia - Clinical Manifestations
Signs and Symptoms: fever cough dyspnea sputum production chest pain hemoptysis mental confusion Pneumonia Pneumonia - Diagnostic Procedures Pneumonia - Diagnostic Procedures Expectorated sputum Blood cultures Chest X-ray XInvasive procedures: transtracheal aspiration, bronchoscopy, transthoracic bronchoscopy, aspiration, open lung biopsy Expectorated sputum gram-stain: false positive/negative gram culture 50% sensitivity Blood cultures 15 - 25% positive with S. pneumoniae; less pneumoniae; with other pathogens Chest X-ray X confirms diagnosis presence of coexisting conditions considerable overlap amongst etiologies Acute Pneumonia - Treatment
1. Initial, empiric therapy is based on: CAP vs HAP, epidemiology comorbid illness, 65 yrs > age < 65 yrs severity of illness initial lab results Streptococcus pneumoniae carried in upper respiratory tract of 5 to 10% of adults commonest cause of CAP and bacterial meningitis ranks among the 10 leading causes of death in the U.S. 2. Subsequent therapy guided by: culture and sensitivity results clinical response to empiric therapy 3. Supportive measures: oxygen, hydration, chest physiotherapy, analgesia, etc. Streptococcus pneumoniae lancet shaped, gram positive cocci ("pneumococcus"), usually in pairs ("pneumococcus"), aerobic (facultative anaerobe) - hemolytic; often mucoid colonies 84 serotypes based on polysaccharide capsule "Typical pneumonia" Streptococcus pneumoniae Virulence factors: capsular polysaccharide - antiphagocytic toxins - pathogenic role not known; (pneumolysin, neuraminidase) pneumolysin, Factors predisposing to infection include: age lack of a spleen influenza virus infections Streptococcus pneumoniae - Epidemiology male : female = 3:2 incidence increases with age > 40 yrs peaks in winter and early spring isolation not required carrier rates higher and more prolonged in children Streptococcus pneumoniae
Otitis media Mastoiditis and sinusitis Meningitis Endocarditis Arthritis Peritonitis Streptococcus pneumoniae
Antimicrobial susceptibility: Penicillin is treatment of choice Recent increase in resistant strains - 10% Resistance due to altered penicillin-bindingpenicillin- bindingprotein (PBP) Cephalosporins, vancomycin used for Cephalosporins, serious infections due to resistant strains Pneumococcal Vaccine contains 23 serotypes of pneumococci covers about 90% of types which cause bacteremia and meningitis type specific immunity for at least 5 yrs efficacy 80%; 50 - 70% in elderly; ineffective under 2 yrs of age Pneumococcal Vaccine Recommended usage according to the Canadian Immunization Guide (1993): All persons over 64yrs of age asplenic or individuals with poor spleen function Immunosuppressed patients chronic heart, liver, lung or kidney disease or HIV, alcoholics, or diabetics ...
View Full Document
This note was uploaded on 05/09/2010 for the course LMP 232 taught by Professor Crandall during the Spring '10 term at University of Toronto.
- Spring '10