Lower Respiratory Tract Infections Flashcards
What are the 5 main infections of the lower respiratory tract?
bronchitis bronchiolitis influenza pertussis pneumonia
What are the natural defenses of the lower respiratory tract?
albeolar macrophages (most important)
complement components
alveolar liing fluid containing surfactant, phospholipids, neutral lipids, immunoglobulin, Factor B and B cells and T cells
What are some of the mechanisms bugs use to avoid phagocytosis?
- capsule production
- toxin production -
- parasits and fungi just too big to engulf
- replication INSIDE cells to hide
- mimicry - parasites use surface proteins similar to host 0 look like self
What are some of the ways bugs can survive within the macropahge?
- inhibit lysosome fusion with the phagosome
- just excape from the phagosome
- resistant to killing and digestion in the phagolysosome
- groth in the phagocytic cell
What is bronchitis an infection of?
Infection and inlammation of the trachea and bronchi but NOT the alveoli
Is bronchitis usually viral or bacterial?
viral
What does bronchitis usually follow?
usually occurs after a viral upper respiratory infection that extends into the trachea, bronchi and bronchioles.
What does bronchitis present with?
cough (dry at first them productive), chest pain and fever, malaise, HA, sore throat
How do you differentiate between a bronchitis and a pneumonia?
You can’t really make the differentiation clinically - need to use a CXR. CXR will be normal in bronchitis but will have infiltrates in pneumonia
What are the common viral causes of bronchitis?
basically the ones that cause rhinitis….
rhinovirus parainfluenza virus respiratory syncytial virus influenza A, B, C Coxsckie A B Adenovirus
Although bronchitis is rarely bacterial, what are the two possibilities?
mycoplasma pneumoniae
chlamydia pneumoniae
On to bronchiolitis…..
What is it inflammation of?
the bronchial tree as low as the bronchioles
NOT the alveoli
Who gets bronchiolitis and why?
babies younger than 1 yr of age because they have narrower airways so it doesn’t take much inflammation to close them down
What’s the most common cause of bronchiolitis?
RSV - by a long shot
What can be given to high risk patients with RSV bronchiolitis?
passive immunization with anti-RSV antibodies
RespiGam (immunoglobulin) or palivizumab (humanized monoclonal antibody)
high risk = premature, cystic fibrosis, congenital heart disease, immune deficienty
Bronchiolitis tends to start like a normal head cold, but what symptoms will it progress to?
tachypnea tachycardia fever diffuse wheezing inspiratory crackles nasal flaring vomiting cyanosis hyperinflation of lungs
What are some risk factors for develping bronchiolitis besides age?
bottle feeding, prematurity, exposure to cigarette smoke, living in crowded situations
What bacteria causes whooping cough?
Pertussis is caused by bordatella pertussis
What are the characteristic symptoms of pertussis?
starts with a normal head cold
then progresses to severe paroxysms of coughing with an inspiratory whoop or post-tussis vomiting
What are some of the possible complications of the whooping cough?
hemoptysis, subconjunctival hemorrhages, hernias, seizures and death
What are the 3 stages of pertussis?
- catarrhal stage - bacteria in respiratory tract cause cold symptoms
- Paroxysmal stage - severe uncontrollable coughing
- convalescent phase - bacteria decreases, no longer cause symptoms but cilia are still trying to recover, so you’re prone to secondary bacterial infection during this stage
What does pertussis use to attach to the ciliated epithelial cells?
filemtneous hemagglutinin
What toxins does pertussis produce and what do they do?
the pertussis AB toxin will enter ciliated epithelial cells and cause an increase in cAMP leading to massive overproduction of mucous
The pertussis tracheal toxin is a cytotoxin which will kill the ciliated endothelial cells
Who common gets pertussis?
adolescents and adults (older patients have better outcomes tha nyounger patients)
but the most severe cases are in children under 1 yr of age
How can you make the diagnosis of pertussis based on lab findings?
it’s a gram negative coccobacilli, but hard to grow in culture
that’s why growth on a selective media - bordet-genous agar will give you a definitive ID
What’s the treatment for pertussis?
antibiotics are NOT effective once they’ve reached the second stage, because it’s the toxin that’s causing the issue now
So provide supportive care and give antibiotics to patient contacts
What’s the most effective means to prevent pertussis?
the DTap/TDap baccine
On to influenza..
What are the two types of influenza that can cause flu epidemics?
A and B cause epidemics
C just causes a head cold
What are the symptoms of flu?
sudden onset fever, chills, rigors, headache, congested conjunctiva, extreme prostration with myalgia in back and limbs, nonproductive cough
diarrhea and vomiting can be present in children
What is the main complication with flu?
secondary bacterial pneumonia with staph aureus, H influenzae, strep pneumoniae, strep pyogenes
Flu infection rates are highest in what age group? Flu mortality rates are highest in what age group?
little kids get it
old people die form it
How many flu strains are covered by the flu shot?
three - two A and one B
Why is the flu genome structure significant?
It’s a single stranded negative sense, segmended genome (class 5)
means it has a high level of mutation rate and different strains that infect the same cell can swap info
Where do most of the mutations cause changes for the flu virus?
areas for antibody binding - the neuraminidase
this allows the flu to escape the adaptive immune system from year to year
What is antigenic shift? Antigenic drift?
antigenic shift is when major changes in antigens occur due to gene reassortment in an influenza virus (from multiple strains infecting the same cell)
antigenic drift occurs when minor changes in antigens occur due to gene mutations.
One to pneumonia….what’s it an infection of?
inflammatory condition of the lung in which fluid fills the alveoli
Pneumonia wins the price for what?
the most common infectious cause of death in the US
What bacterial is the MOST common cause of community-acquired pneumoniae?
streptococcus pneumoniae
What are the symptoms of typical pneurmonia?
sudden osnet of chills, fever, dyspnea, productive dough with purulent sputum and pleuritic chest pain. exam with fever, tachypnea, tachycardia and crackles
What are the symptoms of atypical pneumonia?
more gradual onset of nonproductive cough and dyspnea, extrapulonary signs like HA, sort throat and diarrhea more prominent, fever, tachypnea, tachycardia
How will CXR differ in typical and atypical
typical = consolidations atypical = pathy or interstitial infiltrates with no signs fo consolidation
What are the usual causes of atypical pneumonia?
Mycoplasma pneumonia (walking pneumonia) Chlamydia pneumonia (adults with pharyngitis) Legnionella pneumoniae (severe)
Although most pneumonia is bacterial, you can get viral pneumonaie in kids. WHat are the common viruses here?
RSV
influenza
CMV
What pneumonia is seen with AIDS?
pneumocystis jirovecii
What are the two most likely causative microorganisms for pneumonaie in neonates? birth to 6 weeks….
streptococcus agalactiae (group B strep)
escherichia coli
What are the 4 most common causative microorganisms for pneumoniae in children? 6 wks to 18 yrs?
viruses = RSV
mycopalsma pneumoniae
chlamydia pneumonia
streptococcus pneumoniae
WHat are the 3 most common causative microoganisms for pneumoniae in adults 18-40 yrs?
mycoplasma
chlamydia
streptotoccus pneumonaie
What are the 4 most common causative microorgnisms in adults 40-65?
streptococcus pneumoniae
haemophilus influenzae
anerobic bacteria
viruses
What are the 5 most common causative agents in the elderly over 65?
streptococcus pneumoniae viruses anerovic bacteria haemophilus influenzae gram neg rods
What are the two most common nosocomial causative agents?
gram negative rods like klebsiella or pseudomonas
staphylococcus aureus (MRSA)
What are the 6 most common causative agents in the immunocompromised?
gram negative rods streptococcus pneumonaie fungi filamentous bacteria pneumocystic jirovecci viruses
What’s the group of bacterial pneumoniae associated with gross aspiration?
anerobes
What’s the bacterial pneumoniae associated with alcoholics?
streptococcus pneumoniae
klebsiella pneumoniae
anaerobes
What’s the bacterial pneumoniae associated with IV drug use?
staph aureus
What’s the bacterial pneumoniae associated with post-viral secondary infection?
staph aureus or strep
What’s the bacterial pneumoniae associated with chronic steroids?
nocardia asteroides
