export_bacterial lrt iii Flashcards
Mycobacteria structure
Lipid-rich cell walls
Acid-fast rods
Active vs. latent forms of TB epidemiology
Active is only 10% of infected people
TB has a 10% chance of converting from the latent form to the active form
Primary TB
Initially Mtb enters the body
Clearance can occur
Progress to active or latent TB
Latent TB
Macrophages form granulomas that wall the TB off because the Mtb evades destruction
Active TB
Typically in immunocompromised patients
Main concern with active TB
Rapidly dividing Mtb results in increased CMI activation, causing more caseous necrosis and inflammation
Active TB symptoms
Gradual onset
Weight loss
Night sweats
Cough (dry-severely productive)
Reactivation TB symptoms
Can be asymptomatic and infectious (TB escapes granulomas and spreads via exhalation)
Symptoms same as active
Diagnosis for latent TB
Ghon focus - lung lesion in the lung tissue, calcification
Ghon complex - lung lesion and calcification in an affected hilar node as well as lung tissue
Diagnose active TB
Focal infiltration with cavitation
Immuno-diagnosis of TB
Skin test
IFN-gamma release
Complication with skin test
If patient has received BCG vaccination
IFN-gamma required to diagnose
Treatment of TB
Isoniazid (INH)
Ethambutol
Pyrazinamide
Rifampin
Effect of isoniazid
Inhibits mycolic acid sythesis
Side-effects of isoniazid
Hepatoxicity
Must be observed taking medication correctly
Prevention of TB
BCG vaccine
BCG vaccine
Mycobacterium bovis
Not completely protective
Not commonly used in the US, but is in Europe, Asia, Africa, South/Central Americas
Effect of AIDS on TB
Infection risk much greater
Progression to active TB much more likely
Reactivation risk is also higher
MDR strains prevalent in populations with high HIV infection
Nontuberculous mycobacteria
Atypical
Mycobacterium avium-intracellulare
Mycobacterium kansasii
Mycobacterium avium-intracellulare
Complex of several mycobacteria
Pulmonary infection resembling TB
Mycobacterium kansasii
More common in the elderly
Chronic gradulomatous pulmonary disease
Seen in COPD patients
Laryngitis, tracheitis, and epiglotitis symptoms and cause
Hoarseness, burning pain
Most likely viral
Other causes include GAS, haemophilus influenzae and staph. aureus
Haemophilus influenzae serotype B (HiB) characteristics
Gram-negative, coccobacilli
Fastidious (requires NAD and hemin)
Polysaccharide capsule - PRP
HiB virulence factors
LPS
IgA protease
PRP
HiB main epidemiology
Pediatric pathogen
HiB treatment
High mortality if untreated
Severe cases - broad-spectrum cephalosporin
Less severe cases - amoxicillin (if sensitive)
Vaccination for HiB
Conjugate vaccine - PRP capsule linked to protein carrier
Bacterial bronchitis onset and cause
Acute
Mainly caused by mycoplasma pneumoniae
Bordetella pertussis characteristics
Gram-negative coccobacilli
Fastiduous
What does bordetella pertussis cause
Whooping cough - paroxysmal cough
Increased secretions, decreased mucociliary clearance
Major adhesins of pertussis
Filamentous hemagglutinin (binds to ciliated epithelial cells)
Pertussis toxin
AB toxin
Elevate cAMP, increase in respiratory secretions - paroxysmal cough
Diagnose pertussis
Culture
Nucleic acid amplification test
Serology
Treatment for pertussis
Supportive therapy
Macrolides
Prevent pertussis
DTaP vaccine
