Respiratory System Infections Flashcards
What is the respiratory system divided into?
upper tract
lower tract
Upper tract of the Respiratory sytem
mouth nose (nasal cavity, sinuses) Pharynx epiglottis larynx
Lower Tract of the Respiratory System
trachea
bronchi
bronchioles
alveoli
What is the most common portal of entry?
the respiratory tract
What does the first line of defense include in the respiratory system?
nasal hairs, cilia, mucus
What does the second line of defense include in the respiratory system?
macrophages
What does the third line of defense include in the respiratory system?
pathogen-specific secretory IgA
Where is the normal biota for the respiratory normally found?
in the upper respiratory tract
What bacteria are common in the normal biota of the RS?
Gram-positive bacteria; streptococci and staphylococci
Which bacteria that are part of the normal biota can be potentially pathogenic?
streptococcus pyogenes haemophilus influenzae streptococcus pneumoniae neisseria meningitidis staphylococcus aureus
What colonizes the oral mucosa?
candida albicans (yeast)
What is streptococcal pharyngitis characterized by?
difficulty swallowing
fever
red throat with pus patches
enlarged tender lymph nodes; localized to neck
What is the causative agent for streptococcus pharyngitis? what are its characteristics?
streptococcus pyogenes
gram +
coccus in chains
beta hemolytic (complete hemolysis of RBC)
What is streptococcus pyogenes commonly referred to as
group A streptococcus
due to group A carbohydrate in cell wall
basis for identification from other organisms
What are the virulence factors of streptococcal pharyngitis?
streptolysin O and S for hemolysis
Protein G used to inactivate antibody
More virulence factors used by S. pyogenes in other diseases- superantigens ect
What complications of infection can occur during acute illness of streptococcal pharyngitis?
scarlet fever
acute glomerulonephritis
acute rheumatic fever
How is S. pyogenes diagnosed?
pharyngeal swab test
use antibodies to detect group A streptococci
High rate of false-negative results (confirm with culturing)
How do you culture S. pyogenes cultured?
plated on sheep blood agar
causes hemolysis
distinguish from beta-hemolytic group B streptococci and enterococci
bacitracin disc test
What is the treatment for streptococcal pharyngitis?
penicillin as many group A streptococci resistant to erythromycin
use first-generation cephalosporin (cephalexin) for patients with penicillin allergies
What is the prevention of streptococcal pharyngitis
no vaccine
prevention by good hand washing
What is used for patients with penicillin allergies to treat S. pharyngitis?
cephalosporin (cephalexin)
What are the symptoms for the common cold?
malaise sratchy mild sore throat runny nose cough and hoarsness nasal secretion no fever Symptoms usually disappear within a week
What is the causative agent of the common cold?
30%-50% caused by rhinoviruses
more than 100 species of rhinoviruses
non-enveloped
single-stranded RNA genome
What is the pathogenesis of the rhinovirus
virus attach to specific receptors on respiratory epithelial cells and multiply in cells; large numbers of viruses released from infected cells
