Diebel: Causative Microorganisms of the URT Flashcards
What is the most common cause of colds?
Rhinovirus
What family does rhinovirus belong to?
Picornaviridae (small RNA viruses)
What is the clinical presentation of rhinovirus?
common cold
How does rhinovirus spread?
Contact or aerosol formation
How does rhinovirus initiate infection?
Binds to ICAM-1 on URT EPITHELIAL cells>
replicates inside cells and spreads to surrounding tissue w/out killing infected host cells
What causes “disease” w/ rhinovirus?
immune response to infection
LOCAL INFLAMMATION>
Exudate and increased ICAM-1 expression>
enhances ability of virus to spread and cause further infection
What can the exudate produced by rhinovirus lead to?
It can block airways which can lead to bacterial sinusitis or otitis media.
What type of immunity does an individual w/ rhinovirus acquire?
IgA immunity to rhinovirus serotype of the infection
How do you diagnose rhinovirus?
pt’s symptoms
How do you treat rhinovirus?
supportive care
NO vaccine available
What family do the parainfluenza viruses belong to?
Paramyxoviridae
What surface proteins are common to ALL paramyxoviridae viruses and what do they do?
VIRAL FUSION (F) surface proteins> cause infected cells to form multinucleate giant cells
How does parainfluenza virus cause tissue damage?
Cytopathic effects of the virus and immune response to the infection
How does parainfluenza virus present in children?
croup (laryngotracheobronchitis)
pneumonia
How does parainfluenza virus present in adults?
Common cold (moderately severe)
How is parainfluenza virus passed?
Inhaled through aerosols
How does parinfluenza virus infect?
Infects the larynx mucosa via contact of the viral hemagglutinin (HA) envelope protein w/ sialic acid on cell surfaces (leads to endocytosis).
What envelope protein is important for cleaving HA bound to sialic acid and permits viral spread?
Viral neurominidase (NA)
How does parainfluenza infection lead to narrowing of the lumen and obstruction of inspiration?
As the virus spreads downward to the TRACHEAL AND BRONCHIAL epithelium it causes inflammation and swelling of mucous membranes.
Obstruction of inspiration leads to what?
Inspiratory stridor
Obstruction of expiration leads to what?
barking cough–> croup
How can parainfluenza cause pneumoniae?
It can also invade the lower RT
How do you diagnose parainfluenza? What laboratory findings can confirm it?
Pts symptoms
Labratory confirmation through hemaglutination activity in respiratory secretions and serology (anti-HA antibodies)
How do you treat parainfluenza?
Supportive care (cool mist; oxygen in severe cases)
Corticosteroids
Why is Coronarvirus called coronavirus?
Club-shaped viral proteins projecting out of the viral envelope that look like the corona surrounding the sun
What is the second most common causative agent of the common cold?
Coronavirus (10-20%)
Is coronavirus indistinguishable from a rhinovirus infection?
NO
What is SARS coronavirus?
Severe Acute Respiratory Syndrome
Causes a rapidly progressive VIRAL PNEUMONIA
How does a pt w/ SARS present?
Fever, dyspnea, cough
can progress to respiratory failure and DEATH
What is the clinical presentation for corona virus?
Common cold
How is coronavirus passed?
Inhaled through respiratory aerosols that leads to infection of URT cells
What is the incubation period of coronavirus?
Asymptomatic 3-day incubation period
Cold symptoms caused by coronavirus last for how many days?
6-7 days
How do you diagnose cornoavirus?
Pt symptoms
Serological identificaiton possible but lab diganosis rarely perfromed
How do you treat coronoavirus?
Supportive care
NO vaccines available
How many RNA segments does Influenza C have and how does this compare to Influenza A and B?
7 RNA segments
A and B have 8
How does the virulence of influenza C compare to A?
MUCH less virulent, many infections are ASYMPTOMATIC
Is there an animal reservoir for influenza B and C? What does htis mean?
NO
NO antigenic shifts
Is influenza C responsive to amantadine or rimatadine?
NO
How does influenza C present clinically?
common cold
How is influenza C passed?
inhaled through aerosols
How does influenza C cause infection?
Infects the larynx mucosa via contact of HA envvelope protein w/ sialic acid on cell surface–> endocytosis.
What permits the viral spread of influenza C virus?
NA envelope protein>
cleaves HA bound to sialic acid>
viral spread
Viral replication of influenza C in host cells has what consequences?
DEATH of host cells>
tissue damage and disease
How does the immune response to influenza C contribute to the disease?
IR contributes through production of IL-1 and IFN-y
How do you diagnose influenza C?
Pt’s sxs
How do you get laboratory confirmation of influenza C?
Rapid antigen test on a nasophryngeal swab>
culture swab and detect HA type via a RBC agglutination test
What is the tx for influenza C?
Supportive (acetaminophen, hydration, rest)
No vaccine available for influenza C
What causes hand foot and mouth disease?
Cox A and B
What does hand foot and mouth usually present as?
Vesicles on HAND, FEET, MOUTH
USUALLY IN YOUNG CHILDREN
What is associated w/ 50% of cases of viral myocardidits?
Cox B
How does Cox A more commonly present?
Herpangia
and hand foot and mouth disease
How does Cox B more commonly present?
Pleurodynia
myocarditis
pericarditis
What sxs are common to both Cox A and B?
Aseptic meningitis
paralysis
URI
What does Cox virus typically occur?
Summer to fall
How is Cox transmitted?
Fecal oral
aerosal
What is the pathogenesis of Cox?
GI tract>
infects mucosal epithelial cells>
Replicates and spreads to cause viremia>
infects/destroys other cell types
What is the pathogenesis of Cox A?
Infects skin and mucosal epithelium>
forms vesicles>
herpangina (red oropharynx vesicles, fever, sore throat)>
hand foot and mouth
What is the pathogenesis of Cox B?
Infects heart and pleural surfaces>
Pleurodynia, myocarditis, pericarditis
What is the pathogenesis for how Cox A and B cause aseptic meningitis and paralysis?
Infect MENINGES and ANTERIOR HORN motor neurons>
aseptic meningitis and paryalysis
How do you diagnose Cox virus?
Isolate virus
serology
What is the treatment for Cox virus?
Supportive
Symptomatic- anti-inflammatory agents
What type of virus is adenovirus and where is it found following infection?
Latent virus found in the TONSILLAR ADENOIDS after infection
How many serotypes of adenovirus are there?
40
Are there vaccines for adenovirus?
Yes
administered AWAY from the primary site of infection
A pt presents with RTI (common cold), conjuntivitis, hemorrhagic cystitis and gastroenteritis. What is causing these symptoms?
Adenovirus
How does Adenovirus spread?
Aerosol
Fecal oral
Direct contact
What is the pathogenesis of adenovirus?
Binds via HEMMAGGLUTININ>
enters and LYSES MUCOSAL CELLS
How does the pathogenesis of adenovirus differ in upper and lower RT?
Upper- RHINITIS and sore throat
Lower- Atypical PNEUMONIA
How do you diagnose adenovirus?
Isolate virus in cell culture
Serology
How do you treat adenovirus?
Vaccine of live viruses of specific serotypes (Only used in military)
Why is treatment mandatory for s. pyognes?
Usually SELF LIMITING
but it can cause Rheumatic and glomerulonephritis
What VF promote the spread of infection of s. pyogenes and lead to inflammation?
Streptokinase (converts plasminogen to plasmin> fibrinolysis) M protein (resists phagocytosis) Hyaluronidase (breaks down CT) DNase (breaks down DNA)
A pt presents w/ PHARYNGITIS, impetigo, ersipelas and cellulitis. What is the causative organism?
STREPTOCOCCUS pygoenes
How is s. pyogenes transmitted?
Part of the normal flora of skin/oropharynx
Transmitted through respiratory droplets
How does s. pyogenes cause pharyngitis?
Transmitted through respiratory droplets>
bacteria adhere and colonize pharyngeal epithelial cells via PILI on surface of bacteria>
Localized inflammation and SORE THROAT and ENLARGED LYMPH NODES
How do you diagnose s. pyogenes?
Throat/skin culture Gram + cocci Beta hemolytic Bacitracin sensitive ASO + anti-stretolysin O abs present
How do you treat s. pyogenes?
Penicillin G
What is the second MCC of bacterial pneumonia inpts w/ COPD and nontypeable H influenzae?
Moraxella catarrhalis
What VFs does Moraxella have?
SPECIALIZED PILI allows for attachment of microorganism to mucosal surface
ANTIGENIC VARIATION to evade host IR
ENDOTOXIN
CAPSULE
What are the three types of infection that moraxella can cause?
otitis media
sinusitis
pneumonia
How does moraxella normally colonize?
Colonizes the NASOPHARYNX and spreads to the MUCOSAL SURFACES>
Releases ENDOTOXIN>
Inflammatory response
How can you diagnose moraxella?
Hydrolyzes tributyrin
Produces DNase
Reduces nitrite/nitrate
Dones’t ferment sugars
How do you treat moraxella?
Amoxicillin-clavulanate
Cephalosporins
TMP-SMX
When are DTaP vaccines given?
2,4,6 and 18 mos, before starting school and every ten years after that
What carries diptheria toxin?
PHAGE–> only lysogenic orgs can cause systemic disease
How does diptheriae present locally and systemically?
Locally- pseudomembrane and AIRWAY OBSTRUCTION
Systemically- myocarditis and polyneuritis
How does diptheriae cause airway obstruction?
Enters nasopharynx via RESPIRATORY DROPLETS>
creaets gray fibrinous exudate (bacterial cells, WBC, necrotic mucosa)>
Block airways
What does the diptheriae secrete? What does this do in the cell?
AB toxin that ribosylates EF2 and prevents PROTEIN SYNTEHSIS
What is the ultimate toxic affect of diptheria toxin?
cardiac issues
NS issues
How do you diagnose diptheriae?
Gram + rod
aerobic
Black colonies on Potassium tellurite
How do you treat diptheriae?
Antitoxin
penicillin
erythromyacin
What is prophylaxis for diptheriae?
DTaP w/ boosters every 10 years
What is the major cause of community acquired pneuomonia?
s. pneumonaiae
What serves as the ags for the pneumovax vaccine?
Capsule sugars
How does s. pneumoniae present locally?
Otits media
LOBAR pneumonia
What is the pathogenesis of s. pneumoniae? How do they evade host defenses?
Respiratory droplets> nasopharynx epitheluim> evade host defenses by CAPSULE FORMATION and IgA PROTEASES> spread to middle ear and SINUSES> Alveoli> Lobar pneumoniae
How do you diagnose s. pneumoniae?
Gram + diplococcic alpha hemolytic catalase - susceptible to optochin Quelling rxn
How do you treat S. pneumoniae?
Penicillin/cephalosporins
Preventative- pneumovax vaccine
What is the difference between H influenze type B and non-typeable H influenza?
H influenza type B- encapsulated and INVASIVE
non-typeable- colonize locally
To whom does non-typeable H influenzae pneumonia occur most often?
Adults w/ COPD
Recent viral infection
How does Haemophilius influenza type B spread?
Infects humans via respiratory droplets> URT> local inflammation and EPIGLOTTITIS AND OTITS MEDIA> invades submucosa and blood stream> PNEUMONIA
How does Haemophilius influenza type B evade host defenses?
IgA protease
Capsule
What is the microorganism? Gram - Requires hemin and NAD on chocolate agar Immunofluorescence \+ Quelling Test
Haemophilus Influenza type B
How do you brevent haemophilus influenza and treat it?
Hib vacccine
Rifampin for close contacts
Third generation cephalosporin (ceftriaxone)
What proteins does RSV use to attach to cells and to fuse infected cells?
G proteins- attachment
F protein- fuse cells
What is the major respiratory pathogen in young children?
RSV–infects everyone by age 3
What to conditions present w/ wheezing?
Asthma and RSV
What is the pathogenesis of RSV?
Attaches to bronchiolar/alveolar epitheilum via G protein>
necrosis and iflammation of bronchioles>
mucous obstruction of airway>
bronchiolitis and wheezing
alveoli>
pneumonia
What can prevent RSV?
Recurrent infectoin builds IgA immunity against futher infection
How do you treat RSV?
Supportive
Albuterol
Preventative- Synagis