Bacterial lower respiratory infections Flashcards
What pathogens are associated with typical pneumonia?
- Streptococcus pneumoniae2. Haemophilus influenzae3. Staphylococcus aureus 4. Moraxella catarrhalis 5. Oral anaerobic bacteria
What pathogens are associated with atypical pneumonia?
- Mycoplasma pneumoniae 2. Chlamydophila pneumonia3. Legionella pneumophila 4. Mycobacterium tuberculosis 5. Non-tuberculosis mycobacteria 6. Nocardia spp.
What are complications of pneumonia?
- Pleural effusion 2. Hematologic (anemia, coag, thrombocytopenia) 3. Chronic (dec pO2, bronchiestasis)
What are the most important causative agents of hospital acquired pneumonia?
- Gram negative enteric bacteria 2. Pseudomonas aeruginosa 3. Staphylococcus aureus4. Oral anaerobic bacteria
What do labs look like with CAP?
- CBC: elevated WBC, left shift 2. Blood culture: positive indicates severe disease3. Sputum analysis: >25 PMNs and
What are the properties of streptococcus pneumoniae?
- Gram positive, diplococci in chains 2. Alpha hemolytic 3. Catalase negative 4. Many serotypes 5. Capsular polysaccharide 6. Pneumococcal pneumonia
What are the pneumococcal virulence factors?
- Surface adhesins2. IgA protease3. Pneumolysin 4. Teichoic acid and peptidogylcan5. Thick polysaccharide capsule
What is the role of surface adhesins?
- Colonization of pharynx 2. Pneumococcal pneumonia c
What is the role of IgA protease?
- Cleaves IgA, prevents clearance 2. Pneumococcal pneumonia
What is the role of pneumolysin?
- Pore forming toxin2. Colonization3. Invasion4. Inflammation 5. Complement activation 6. Pneumococcal pneumonia
What is the role of teichoic acid and peptidoglycan?
- Inflammation 2. Pneumococcal pneumonia
What is the role of thick polysaccharide capsule?
- Antiphagocytic2. Pneumococcal pneumonia
What is the presentation for pneumococcal pneumonia? 1
- Cough, fever, dyspnea, chest pain2. Crackles3. Sputum production 4. Preceded by several days of rhinorrhea5. Abrupt fever with chills 6. Sever pleuritic chest pain 7. Poor oxygenation 8. Should resolve in 7-10 days untreated
What is the lab diagnosis for S. pneumoniae?
- Gram stain of sputum 2. Alpha hemolysis3. Catalase4. Bile solubility positive 5. Optochin sensitive 6. Urine for pneumococcal polysaccharide
What is the treatment for S. pneumoniae?
- Penicillin (empiric for sensitive strains) 2. Macrolide - azithromycin (empiric) 3. Azithromycin + cephalosporin (empiric, sensitive cases) 4. Antimicrobial susceptibility testing for directed therapy
What is the prevention for S. pneumoniae?
- 23-valent pneumococcal polysaccharide vaccine2. 13-valent conjugated pneumococcal vaccine
What are the properties of S. aureus?
- Gram positive cocci in clusters 2. Catalase positive 3. Coagulase positive
What are the S. aureus virulence factors?
- Coagulase2. Protein A - binds Fc portion of Ab3. Panton-Valentine luekocidin (PVL)
What does Protein A do?
- Binds Fc portion of Ab2. S. aureus virulence factor
What is the role of Panton-Valentine leukocidin?
- Severe necrotizing penumonia 2. Pore forming cytotoxin 3. S. aureus
MRSA is resistant to why type of antibiotics?
- All beta lactams 2. Cephalosporins
What is the treatment for MRSA?
- Linezoid (new 50S inhibitor class) 2. Vancomycin
What are the properties of gram negative bacteria that cause pneumonia?
- Patients generally have an underlying disease2. Cough, purulent sputum (foul if anaerobic), fever, chest pain, dyspnea, crackles3. Any lobe may be affected 4. 25% have pleural effusion 5. Antibiotic resistance is a big problem
What are the pneumonia-causing gram negative bacteria?
- Klebsiella pneumoniae (facultative anaerobe) 2. Pseudomonas aeruginosa (aerobes)
What is the lab diagnosis for gram negative pneumonia?
- Sputum culture 2. Gram stain 3. Blood culture - 20% are positive
What is the treatment for gram negative pneumonia?
- BSA2. Multiple drug therapy (synergism, MDR prevention)3. Aminoglycoside + beta lactam (gentamycin / cephalexin + tobramycin / ampicillin) 4. Ticarcillin / piperacillin + amikacin (to target pseudomonas)
What are the characteristics of Klebsiella pneumoniae?
- Gram negative rod 2. Non-motile 3. Mucoid colonies (capsule) 4. Strains commonly produce extended-spectrum beta lactamases 5. Oxidase negative
What is the presentation for Klebsiella pneumoniae?
- Classic lobar pneumonia 2. Bloody sputum from necrosis and abscess (currant jelly)
What are the Klebsiella pneumoniae virulence factors?
- LPS 2. Capsule (~80 serotypes)
What is the treatment for Klebsiella pneumoniae?
Same as other gram negative pneumonias
What is the prevention for Klebsiella pneumoniae?
- Disinfection of environment 2. Use of sterile respiratory equipment
What are the properties of pseudomonas aeruginosa?
- Gram negative rods, flagellated 2. Obligate aerobe 3. Sugar fermentation negative 4. Oxidase positive 5. Blue / yellow-green pigments 6. Culture smells like grapes 7. Can metabolize almost all organic compounds
What are epidemiological properties of pseudomonas aeruginosa?
- Grows in water with minimal nutrients, hand soap, dilute antiseptics 2. Most strains form biofilms
What are the pseudomonas aeruginosa virulence factors?
- Toxin A - halts protein synthesis 2. Leukocidin - pore forming toxin, targets leukocytes 3. Phospholipase C - membrane disruption 4. Capsule - antiphagocytic 5. Pyocyanin - blue compound toxic to host cells 6. Pyoverdin - green iron uptake protein
What is the treatment for pseudomonas aeruginosa?
Antipseudomonal penicillins (ticarcillin or piperacillin) + aminoglycoside (gentamycin, tobramycin, amikacin)
How is pseudomonas aeruginosa related to CF?
- Strains convert from non-mucoid to mucoid (overproducing extracellular polysaccharide), significantly affecting pulmonary function 2. Impairment of respiratory tract immunity3. Biofilms in lungs
What bacteria are responsible for walking pneumonia?
- Mycoplasma pneumoniae2. Chlamydophila pneumoniae 3. Chlamydophila psittaci 4. Coxiella burnetti
What bacterium is responsible for toxic pneumonia?
Legionella pneumophila
What are the symptoms of atypical pneumonia?
- Bronchopneumonia with gradual onset 2. Fever, headache, fatigue, muscle ache, dry cough3. Scant, watery sputum
What is the treatment for atypical pneumonia?
Tetracycline or erythromycin (empiric - absence of signs for pneumococcal pneumonia)
What are the characteristics of mycoplasma pneumoniae?
- Pleomorphic2. No peptidoglycan layer 3. Membrane contains sterols4. Culture requires supplementation with sterols and nucleotide precursors 5. Fried egg colony morphology
What happens with low dose transmission of mycoplasma pneumoniae by respiratory droplets?
Tracheobronchitis