Intro to Micro Respiratory Infectious Disease - Zimmer Flashcards
What are the major mechanisms of defense of the upper respiratory tract (URT)?
(Hint: 5 mechanisms)
- Mucociliary lining of the nasal cavity (with help of “baffle plates”)
- Change of direction of the airway from the sinuses to the pharynx (location of adenoids)
- The ciliary elevator
- Normal flora competition (Staphylococci)
- Alveolar macrophages eliminate microorganisms in the lungs
What are the major mechanisms viruses employ to avoid these defenses?
- Cytopathic effect – viral infection disrupts normal cell physiology which can lead to cell death and disease.
- Host immune response – response of the host to the virus causes illness.
- Tumorigenesis – viral infection promotes uncontrolled proliferation of infected cells.
What are the major mechanisms bacteria employ to avoid these defenses?
- Toxin production – bacteria release toxin that causes illness.
- Host immune response – response of host to bacteria that causes illness.
- Bacterial proliferation and invasion – growth and spread of bacteria that causes damage that is significant in illness.
What is the medical term for the common cold?
Rhinitis
What is the most common pathogen causing the common cold?
Rhinovirus
What is the second most common pathogen that causes the common cold?
Adenovirus
Why is the common cold so prevalent and we get so many bouts of it every year?
There are at least 100-200 immunologically distinct forms rhinoviruses, 50 immunologically distinct adenoviruses, and several types of coronaviruses that can cause the common cold (other minor viral causes as well).
How do Rhinoviruses infect the cells lining the nasal passages and the pharynx following attachment?
Utilize the intercellular adhesion molecule (ICAM) ICAM-1 of the cells.
When do symptoms peak in Rhinitis?
2-5 days post-infection
Ciliated epithelial cells regenerate how many days after being destroyed by localized inflammation and lytic infection of Rhinovirus?
day 14 post infection
What kind of infection can happen simultaneously or directly following Rhinitis?
Secondary bacterial infection by normal flora.
- Results in:
- change from clear nasal secretions to → purulent (cloudy/yellow) nasal secretions
- Sinus blockage can result in → sinusitis or otitis media
- infection gaining access to the lower respiratory tract causing → bronchitis
What time of year are Rhinitis infections most common?
Usually seen in the winter, with the exception of adenovirus infections (year round).
What is the viral classification of rhinovirus?
- DNA
- Nucleocapsid shape
- Class
- Family
- RNA virus
- Icosahedral Nucleocapsid
- Nonenveloped
- SS (+) Nonsegmented Genome (Class IV)
- Picornaviridae
What is the viral classification of adenovirus?
- DNA
- Nucleocapsid shape
- Class
- Family
- DNA virus
- Icosahedral Nucleocapsid
- Nonenveloped
- DS linear DNA (Group I)
- Adenoviridae
What is the viral classification of coronavirus?
- DNA
- Nucleocapsid shape
- Class
- Family
- RNA virus
- Helical Nucleocapsid
- Enveloped
- SS (+) Nonsegmented Genome (Class IV)
- Coronaviridae
What is the viral classification of Paramyxovirus?
- DNA
- Nucleocapsid shape
- Class
- Family
- RNA virus
- Helical Nucleocapsid
- Enveloped
- SS (-) Nonsegmented Genome (Class V)
- Paramyxoviridae
What is the viral classification of Influenza virus A, B, C?
- DNA
- Nucleocapsid shape
- Class
- Family
- RNA virus
- Helical Nucleocapsid
- Enveloped
- SS (-) Nonsegmented Genome (Class V)
- Orthomyxoviridae
What is the viral classification of Coxsackievirus A + B?
- DNA
- Nucleocapsid shape
- Class
- Family
- RNA virus
- Icosahedral Nucleocapsid
- Nonenveloped
- SS (+) Nonsegmented Genome (Class IV)
- Picornaviridae
- Enterovirus
What are the most common causes of pneumonia in young children?
- RSV
- Parainfluenza virus (Paramyxovirus)
What are the most common causes of aseptic meningitis?
- Coxsackievirus
- Echovirus
- Mumps virus
What are the most common causes of palm and sole rash?
- Syphilis
- RMSF
- Coxsackievirus
What are the most common causes of conjunctivitis?
- H. influenza
- Adenoviruses
- S. pneumoniae
What is the most common predisoposing factor for Sinusitis? Other factors?
- Most common:
- viral infection (URI)
- Others:
- allergies
- structural problems in the skull
What is acute rhinosinusitis?
inflammation or infection of the mucosa of the nasal passages and at least one of the paranasal sinuses that typically lasts no longer than 4 weeks
What are the two most common pathogens causing community acquired acute bacterial rhinosinusitis infections? Others?
- Most common:
- Streptococcus pneumoniae
- Haemophilus influenzae
- Others:
- Streptococcus pyogenes
- Staphylococcus aureus
Although rare, fungal sinusitis infections are usually identified when?
after antibacterial drugs fail to clear the sinus infection