Upper Respiratory Infectious Disease I (Zimmer) Flashcards
How do bacteria cause diease?
- Toxin production
- host immune response
- bacterial proliferation and invasion
How do VIRUSES cause disease?
- cytopathic effect - disrupts normal cell physiology
- host immune response
- tumorigenesis
5 things that help rid the respiratory tract of potential pathogens
- mucociliary lining of the nasal cavity
- contains lysozyme, lactoferin and secretory IgA antibodies
- Change of direction of airway from sinuses to pharynx
- alveolar macrophages - found in lungs
- ciliary elevator
- normal flora (staphylocci)
What are the 2 main obstacles that an organism must overcome to cause infection in respiratory tract?
- Avoid/survive mucus layers of URT - leads to swallowing of pathogen
- avoid phagocytosis or be able to surivive and or multiply in phagocytic cell
Explain how swirling of air prevents pathogen invasion
turbinate bones are covered with mucus and they collect particles that arent filtered by nasal hairs. Bones cause air to swirl as it passes over that forces the potential pathogens to make contact.
Where is the mucociliary elevator found?
What is it composed of?
what can paralyze the cilia of it?
- found in the bronchi, bronchioles and nose
- composed of:
- mucus producing goblet cells
- ciliated epithelium
- smoking can paralyze
What conditions must be met to establish a respiratory tract infection?
- there must be sufficient dose of microorganisms inhaled in order to establish an infection
- infectious particles must be airborne
- airborne particles must be viable in the air.
- organism must be deposited on tissue susceptible to infection in the host.
List 4 common URI diseases and the common associated pathogens:
- common cold - mostly viral - rhinoviruses common
- Sinusitis - Spneumoniae, H. influenza
- Pharyngitis - viral + bacterial (S. pyogenes, C. diptheriae)
- Laryngitis/Croup - mostly viral (Parainfluenza, RSV)
Common Cold (rhinitis)
Causative bugs?
when does it occur?
Symptoms:
Spread?
- caused by rhinoviruses > coronaviruses > adenoviruses
- more often in winter (except adenovirus)
- Symptoms
- nasal stuffiness, sneezing headache
- fluid in nose, tired, watery eyes, slight fever, scratchy throat, anorexia
- cough if lower respiratory
- Spread = hand to hand or through other objects
Common cold (rhinitis)
how does virus infect?
What are complications?
Diagnosis
Treatment
- virus infects nasal passages following direct contact of surfaces or inhalation of infectious droplets
- complications
- secondary bacterial infection, sinusitis, otitis media, bronchitis
- diagnosis based on symptoms + time of year
- supportive therapy
How does rhinovirus infect the nose?
infects cells of nasal passages and pharynx after attaching using ICAM-1
ciliated epithelial cells are destroyed by local inflammation and infection.
inflammation causes exudate and increased ICAM expression
exudate can block passages which can lead to sinusitis.
symptoms peak 2-5 days.
Rhinovirus
Type of virus
capsid
envelope
genome
family
- RNA virus
- icosahedral nucleocapsid
- NON enveloped
- ss+ class IV
- picornaviridae
40-50% of common cold
Coronavirus
Type of virus
capsid
envelope
genome
family
- RNA
- helical
- enveloped
- ss+ - Class IV
- coronaviridae
10% of colds
influenza virus A, B, C
Type of virus
capsid
envelope
genome
family
- C is more cold symtpoms not flu
- RNA virus
- helical
- enveloped
- ss (-) Class V genome segmented
- Orthomyoxviridae
Coxsackie A and B
Type of virus
capsid
envelope
genome
family
- RNA virus
- icosahedral
- NON enveloped
- ss+ Class IV
- picornavirdiae - enterovirus
Paramyxovirus (Parainfluenza)
Type of virus
capsid
envelope
genome
family
- RNA
- helical
- enveloped
- ss- Class V nonsegmented
- paramyxovirdiae
Adenovirus
Type of virus
capsid
envelope
genome
family
- DNA virus
- Icosahedral
- NON enveloped
- DS linear DNA (group I)
- Adenoviridae
What 3 bugs are the most common cause of conjunctivitis?
- H. influenza
- Adenovirus
- S. pneumoniae
Acute Rhinosinusitis
Symtpoms
Length
of cases
- inflammation or infection of mucosa or nasal passage and at least one paranasal sinus that lasts no longer than 4 weeks
- > 11 million cases each year
- sneezing, rhinorrhea, nasal congestion w/postnasal drip, aural fullness, facial pressure, headache, sore throat, cough, fever, muscle aches
- VIRAL URI predisposes
What is the most common cause of sinusitis and how long should it last?
viruses - 5 to 7 days.
when is bacterial sinus infection more likely?
How can we tell?
- follows common cold, dental extractions, rhinitis due to allergies
- Adults
- symptoms > 7 days
- facial swelling
- tooth pain
- Kids
- lasts longer than 10 to 14 days
- fever > 102 w/ pain + swelling
What are the most common causes of acute bacterial rhinosinusitis infections?
- Streptococcus pneumoniae
- Haemophilus influenza
What are other potential sinusitis bugs that aren’t as common?
- Streptococcus pyogenes - also pharngitis
- Staphylococcus aureus
- Moraxella catarrhalis
What is typically seen if antibacterial drugs fail to clear the sinus infection?
- fungal infection
- most common is aspergillus fumigatus
- immunocompromised patients must have the fungal pathogen removed.