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Year 1 Microbiology > Bacterial lower respiratory infections > Flashcards

Flashcards in Bacterial lower respiratory infections Deck (106):

What pathogens are associated with typical pneumonia?

1. Streptococcus pneumoniae2. Haemophilus influenzae3. Staphylococcus aureus 4. Moraxella catarrhalis 5. Oral anaerobic bacteria


What pathogens are associated with atypical pneumonia?

1. Mycoplasma pneumoniae 2. Chlamydophila pneumonia3. Legionella pneumophila 4. Mycobacterium tuberculosis 5. Non-tuberculosis mycobacteria 6. Nocardia spp.


What are complications of pneumonia?

1. Pleural effusion 2. Hematologic (anemia, coag, thrombocytopenia) 3. Chronic (dec pO2, bronchiestasis)


What are the most important causative agents of hospital acquired pneumonia?

1. Gram negative enteric bacteria 2. Pseudomonas aeruginosa 3. Staphylococcus aureus4. Oral anaerobic bacteria


What do labs look like with CAP?

1. CBC: elevated WBC, left shift 2. Blood culture: positive indicates severe disease3. Sputum analysis: >25 PMNs and


What are the properties of streptococcus pneumoniae?

1. 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?

1. Surface adhesins2. IgA protease3. Pneumolysin 4. Teichoic acid and peptidogylcan5. Thick polysaccharide capsule


What is the role of surface adhesins?

1. Colonization of pharynx 2. Pneumococcal pneumonia c


What is the role of IgA protease?

1. Cleaves IgA, prevents clearance 2. Pneumococcal pneumonia


What is the role of pneumolysin?

1. Pore forming toxin2. Colonization3. Invasion4. Inflammation 5. Complement activation 6. Pneumococcal pneumonia


What is the role of teichoic acid and peptidoglycan?

1. Inflammation 2. Pneumococcal pneumonia


What is the role of thick polysaccharide capsule?

1. Antiphagocytic2. Pneumococcal pneumonia


What is the presentation for pneumococcal pneumonia? 1

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?

1. 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?

1. 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?

1. 23-valent pneumococcal polysaccharide vaccine2. 13-valent conjugated pneumococcal vaccine


What are the properties of S. aureus?

1. Gram positive cocci in clusters 2. Catalase positive 3. Coagulase positive


What are the S. aureus virulence factors?

1. Coagulase2. Protein A - binds Fc portion of Ab3. Panton-Valentine luekocidin (PVL)


What does Protein A do?

1. Binds Fc portion of Ab2. S. aureus virulence factor


What is the role of Panton-Valentine leukocidin?

1. Severe necrotizing penumonia 2. Pore forming cytotoxin 3. S. aureus


MRSA is resistant to why type of antibiotics?

1. All beta lactams 2. Cephalosporins


What is the treatment for MRSA?

1. Linezoid (new 50S inhibitor class) 2. Vancomycin


What are the properties of gram negative bacteria that cause pneumonia?

1. 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?

1. Klebsiella pneumoniae (facultative anaerobe) 2. Pseudomonas aeruginosa (aerobes)


What is the lab diagnosis for gram negative pneumonia?

1. Sputum culture 2. Gram stain 3. Blood culture - 20% are positive


What is the treatment for gram negative pneumonia?

1. 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?

1. 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?

1. Classic lobar pneumonia 2. Bloody sputum from necrosis and abscess (currant jelly)


What are the Klebsiella pneumoniae virulence factors?

1. 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?

1. Disinfection of environment 2. Use of sterile respiratory equipment


What are the properties of pseudomonas aeruginosa?

1. 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?

1. Grows in water with minimal nutrients, hand soap, dilute antiseptics 2. Most strains form biofilms


What are the pseudomonas aeruginosa virulence factors?

1. 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?

1. 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?

1. 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?

1. 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?

1. 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?



What is the mycoplasma pneumoniae virulence factor?

P1 adhesin


What does the P1 adhesin do?

1. Binds to base of cilia 2. Ciliostasis 3. Epithelial cell damage / death 4. Defect in mucociliary clearance 5. Mucus / fluid accumulation in lungs


What are the symptoms of mycoplasma pneumoniae?

1. Bronchopneumonia with gradual onset 2. Scant, watery sputum 3. Anemia - IgM response cross reacting with RBCs4. Patchy infiltrates


What is the diagnosis for mycoplasma pneumonia?

1. Microscopy / culture not recommended 2. Cold agglutinin test - will agglutinate at 4 C 3. PCR 4. Serology


What is the treatment for mycoplasma pneumoniae?

1. Tetracycline and macrolide (erythromycin) 2. NOT beta lactams (no peptidoglycan - no target)


What is the prevention for mycoplasma pneumoniae?

None - avoid overcrowded areas


What are the characteristics of chlamydophila pneumoniae?

1. Small, gram negative 2. Obligate intracellular pathogen 3. Atypical pneumonia 4. Implicated in atherosclerotic plaque formation, asthma, MS and rheumatoid arthritis


What is the diagnosis for chlamydophila pneumoniae?

1. Microimmunofluorescence (anti-chlamydophila Ab) 2. PCR


What is the treatment for chlamydophila pneumoniae?

Tetracycline and a macrolide (same as M. pneumoniae)


What is the infectious particle of chlamydophila pneumoniae?

1. Elementary body 2. Reorganizes in the form of a reticular body inside the cell 3. RB undergoes binary fission in inclusion then reorganize back to EB for reinfection


What is the causative agent of Legionnaire's disease?

Legionella pneumophila


What are the characteristics of legionella pneumophila?

1. Gram negative 2. Inside cell - coccobacilli 3. Outside of cell - pleomorphic 4. Difficult to culture (slow, fastidious, high humidity) 5. Mainly exist as parasites of amoeba (intracellularly)


What is the transmission of legionella pneumophila?

Aerosols made from manmade water supplies that harbor legionella and their amoeba host


What is the virulence / pathoenesis of legionella pneumophila?

1. Target and attach to alveolar macrophage using pili, flagella, numerous proteins 2. Enter macrophage in an endocytic vacuole (coiling mechanism)3. Hijacks cell 4. Macrophage and amoeba replication similar


How does legionella hijack the cell?

1. Bacterial proteins injected into cytosol 2. Prevents fusion with lysosome 3. Recruits ribosomes, mitochondria, ER to vacuole now called legionella containing vacuole (LCV) 4. Replication of bacteria to high numbers, cell lyses 5. Inflammation, lung necrosis, systemic toxicity as a result of lysis


What is the clinical manifestation of legionella pneumonia?

1. Severe toxic pneumonia2. Myalgia, headache, rapidly rising fever 3. Dry cough, may become productive 4. Chills, pleurisy, vomiting, diarrhea, confusion, delirium5. Patchy infiltrate on XR6. Progressive illness over 3-6d resulting in shock, respiratory failure or both 7. Elevated WBC


How is legionella pneumonia diagnosed?

1. Culture 2. Direct fluorescent Ab (DFA) detection of organisms 3. Nucleic acid amplification test


What is the treatment for legionella pneumophila?

1. Macrolide or fluoroquinolone 2. NOT beta lactams (because of beta lactamases)


What is the prevention for legionella pneumophila?

Minimize exposure to contaminated aerosols


What are the non-tuberculosis mycobacterium species?

1. M. avium-intracellulare2. M. leprae3. M. kansasii


What are the properties of mycobacteria?

1. Weakly gram positive, acid fast rods 2. Lipid rich cell wall (ie acid fast)


Can acid fast staining confirm presence of Mtb?

1. No2. Can only confirm presence of mycobacteria


What are the components of the mycobacterium cell wall?

1. Membrane2. Peptidoglycan 3. Arabinogalactan 4. Lipoarabinomannin 5. Plasma membrane and cell wall associated protein 6. Mycolic acids 7. Mycolic acid-associated glycolipids


What is the progression of tuberculosis?

1. Mtb inhaled as airborne droplets into lungs 2. Mtb enters alveolus 3. Bacilli taken up and multiply in alveolar macrophages 4. Lymphocytes recruited to infection site 5. Multinucleated giant cells develop 6. Wall of cells, calcium salts, fibrous material forms around giant cells 7. Giant cell walled off from surrounding tissue


How does Mtb enter systemic circulation?

Usually via hilar lymph nodes


What is latent TB?

1. Inability of immune system to kill TB 2. CD4, CD8, and NK cells surround necrotic mass of Mtb infected macrophage - caseous necrosis 3. Granuloma prevents further spread


How is most of the damage caused in a TB infection?

By host's cell mediated immunity


What is a disseminated TB infection?

1. Known as miliary or extrapulmonary TB 2. Granuloma formation can occur at any area of the body


What are the symptoms of active TB?

1. Gradual onset, variable manifestations 2. Weight loss 3. Night sweats 4. Cough progressing from scant sputum to productive yellow / green / bloody discharge


What are the symptoms of primary TB?

Often asymptomatic


What is the diagnosis for latent TB?

1. Rapid lab tests 2. CXR for Ghon focus, Ghon complex


What is a Ghon focus?

1. Lung lesion seen in latent TB 2. Granuloma seen on CXR as it calcifies 3. Can contain live Mtb


What is a Ghon complex?

1. Lung lesion seen in latent TB 2. Calcification seen in a hilar lymph node


What is the diagnosis for active TB?

1. Rapid lab tests 2. Focal infiltration with cavitation on CXR 3. Often in apical posterior segment of both upper lobes on CXR


What are the lab tests for TB?

1. Tuberculin (Mantoux) - intradermal PPD injection 2. IFNy release - from T cells in whole blood stimulated with Mtb antigen 3. Microscopy - acid fast (only shows mycobacteria) 4. Nucleic acid amplification 5. Culture (slow, contamination issues)


When is the IFNy TB test best indicated?

For people who have been BCG vaccinated


What is the treatment for TB?

1. 4 drug cocktail for 2 months followed by 26 months INH and rifampin 2. Isonaizid - inhibits mycolic acid synthesis but hepatotoxic


What is the vaccine for TB?

BCG (not completely protective)


What are the properties of mycobacterium avium-intracellulare?

1. Atypical mycobacteria 2. Complex of several mycobacteria3. Pulmonary infection resembling TB in immunocompromised patients or with lung disease 4. Diagnosis and treatment similar to TB


What are the properties of mycobacterium kansasii?

1. Atypical mycobacteria 2. More common in elderly 3. Chronic granulamatous pulmonary disease4. Seen in COPD patients 5. Diagnosis and treatment similar to TB


What are the characteristics of haemophilus influenzae serotype B (HiB)?

1. Gram negative2. Coccobacilli 3. Fastidious - requires NAD and hemin for growth 4. Typeable has capsule - serotype B most pathogenic 5. Polysaccharide capsule - polyribosylribitol phosphate (PRP) 6. Nontypeable does not have a capsule


What are the disease effects of HiB?

1. Conjunctivitis 2. Sinusitis3. Otitis media4. Tracheobronchitis 5. Meningitis 6. Epiglottitis 7. Purpuric fever 8. Bacteremia


What are the virulence factors for HiB?

1. LPS2. IgA protease 3. Typed strains - PRP


What is the diagnosis of HiB?

Gram staining and culture of blood, nasopharyngeal swab, sputum, spinal fluid


What is the vaccination for HiB?

Conjugate - PRP capsule linked to protein carrier


What is the treatment for HiB?

1. Severe - broad spectrum cephalosporins 2. Mild - amoxicillin (beta lactam)


What is the common bacterial agent for bacterial bronchitis?

Mycoplasma pneumoniae


How does mycoplasma pneumoniae cause bacterial bronchitis?

Adhesin / receptor combination has tropism for bronchial mucosal epithelium (P1 adhesin)


What are the properties of bordatella pertussis?

1. Causative agent of whooping cough2. Gram negative coccobacilli 3. Fastidious 4. Adhere to ciliated respiratory mucosa, multiply, produce toxic factors


At what stage is pertussis at highest level of communicability?

Catarrhal - 1-2 weeks


What are the virulence factors for pertussis?

1. Major adhesins2. Major toxins


What are the properties of the pertussis major adhesins?

1. Filamentous hemagglutinin2. Peractin 3. Fimbrae


What are the properties of the pertussis major toxins?

1. Pertussis toxin - AB toxin 2. Adenylate cyclase / hemolysin toxin 3. LPS


What do filamentous hemagglutinin and peractin do?

Bind to ciliated epithelial cells in pertussis infection


What do the pertussis and adenylate cyclase / hemolysin toxin do?

1. Gratuitous activation of adenylate cyclase2. Increased levels of host cell cAMP 3. Increase in respiratory secretions 4. Paroxysmal cough


What is the diagnosis for pertussis?

1. Need lab tests to confirm 2. Culture - Bordet Gengou agar 3. Nucleic acid amplification test (specific / sensitive)


What is the treatment for pertussis?

1. Supportive 2. Macrolides (azithromycin, clarithromycin)


What is the prevention for pertussis?

DTaP - detoxified pertussis toxin, peractin, filamentous hemagglutinin


What is associated with purulent sputum?

Typical pneumonia (most likely S. pnuemoniae)


What is associated with scant, watery, mucoid sputum?

Interstitial pneumonia (most likely M. pneumoniae)


What is associated with rust colored sputum?

Streptococcus pneumoniae


What is associated with currant jelly sputum?

Klebsiella pneumoniae


What is associated with a large amount of blood in the sputum?

Cavitary TB or lung abscess


What is associated with foul smelling sputum?

Anaerobic bacterial pneumonia