SM 181a - Bacterial Infections Flashcards
List the different clinical manifestations of
typical vs. atypical pneumonias.
- Typical
- Abrupt onset
- Productive cough
- No upper respiratory symptoms
- Frequently severe
- Atypical
- Gradual onset
- Nonproductive cough
- Upper respiratory symptoms
- Extrapulmonary symptoms
- Occurs in younger people
- Usually mild
What are the most common bacterial causes of community-acquired pneumonia?
- Streptococcus pneumoniae
- Staphylococcus aureus
- Haemophilus influenzae
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Legionella pneumophila
- mixed anaerobic bacteria (aspiration pneumonia)
Pneumonia caused by S. pneumoniae can progress to…
Bacteremia
Meningitis
Which area of the lung is most likely to be affected by aspiration pneumonia?
The lung fields that aspiration gets to (dependent lung fields)
Right more likely than left
Posterior lung fields if the patient aspirated while lying on their back
Bordetella pertussis
Gram stain:
Size:
Shape:
Anaerobic/aerobic:
Gram stain: Gram negative
Size: Tiny
Shape: Coccobacilli
Anaerobic/aerobic: Strict aerobe
What are the most common causes of acute bronchitis/tracheitis?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Mycoplasm pneumoniae
- Chlamydia pneumoniae
- Bordetella pertussis
What toxin ADP-ribosylates EF-2?
Diphthera toxin
This causes cells to die and form the oropharyngeal pseudomembrane associated with diphtheria
How does aspiration pneumonia develop?
People with poor gag reflexes aspirate bacteria into their lungs
Who is most likely to get aspiration pneumonia?
People with a depressed gag reflex
- Elderly patients
- People who get siezures
- Anyone who blacks out from drinking
What is the treatment for S. aureus?
- MSSA - Nafcillin/oxacillin
- MRSA - Vancomycin or Linezolid
Pseudomonas aeruginsa
Gram stain:
Shape:
Aerobic/anaerobic:
Gram stain: Gram-negative
Shape: Bacilli
Aerobic/anaerobic: Aerobic (oxidase positive)
Which bacteria are most likely to cause pharyngitis?
- Streptococcus pyogenes
- Chlamydia pneumoniae
- Mycoplasma pneumoniae
- Corynebacterium diphtheriae
How is H. influenzae transmitted?
Direct contact with secretions or respiratory droplets
Colonizes in the upper respiratory tract of healthy individuals
Which bacterial causes of pneumonia will not be detectable in gram-stained sputum specimens?
- Legionella pneumophila*
- Mycoplasma pneumoniae*
- Chlamydia spp.*
- Mycbacterium tuberculosis*
A patient with pneumonia and a really high fever (>40C/104F) and GI symptoms is most likely infected with….
Legionella pneumophilia
- Atypical pneumonia
- Water, air conditioning systems, cooling towers
- GI symptoms
Nosocomial pneumonia is pneumonia that occurs ________ hours after______________
Nosocomial pneumonia is pneumonia that occurs >48** hours after **hospitalization (includes VAP and HAP)
What organism is most likely caused this patient’s pneumonia?
a. H. influenzae or S. pneumoniae
b. M. pneumoniae or C. pneumoniae
b. M. pneumoniae or C. pneumoniae
No lobar infiltrate
How is S. pneumoniae diagnosed?
- Sputum sample
- Numerous gram-positive cocci in pairs and chains
- Many neutrophils
- Culture
- Alpha-hemolytic
(incomplete hemolysis aka green on blood agar)
- Alpha-hemolytic
- Catalase-negative
- Optochin-susceptible
What cells in the body does Mycoplasma pneumoniae bind?
Respiratory epithelium, using protein adhesin P1
How can H. infleunzae be prevented?
Type B capsular conjugative vaccine (Hib)
Give to all infants @ 2mo
Describe the clinical presentation of diphtheria
- Sore throat
- Fever
- Difficulty swallowing
- Cough
- Harseness
- Rhinorrhea
- Oropharyngeal pseudomembrane
Pneumonia accompanied by pharyngitis is most often caused by
C. pneumoniae
What is the treatment for Legionella pneumophila?
Macrolide or fluoroquinolone
Which bacteria are associated with ventilator-associated pneumonia?
- Staphylococcus aureus
-
Enterobacteriaceae
- (Escherichia coli, Klebsiella pneumoniae, Enterobacter spp., Serratia spp.)
- Legionella pneumophila
- Pseudomonas aeruginosa
- Acinetobacter baumannii
- mixed anaerobic bacteria (aspiration pneumonia)
Where in the body does s. pneumoniae colonize?
Oropharynx and nasopharynx
How is S. pneumoniae treated?
Penicillin
If resistant, use vancomycin
What clinical disease is asociated with Bordetella pertussis?
Whooping cough
What is the most life-threatening complication of H. influenzae?
Epiglottitis
Which bacteria is the most common cause of community-acquired pneumonia?
Strep. pneumoniae
Encapsulated H. influenzae primarily affects ____________.
Why?
Encapsulated H. influenzae primarily affects children.
We develop type-specific antibodies against the capsule antigens, so most adults have protective immunity
S. Pneumoniae can infect __________
S. Pneumoniae can infect humans only
_______ is the smallest organism that can be free-living in nature and self-replicating on laboratory medium.
Mycoplasma pneumoniae is the smallest organism that can be free-living in nature and self-replicating on laboratory medium.
Why don’t people get the same s. pneumoniae infection twice?
Anibodies against the capsule are protective
Which enterobacteriaceae are common culprits in hospital-acquired pneumonia?
SEEK
- Serratia spp.
- E. coli
- Enterobacter spp.
- Klebsiella pneumoniae
How can streptococcal pneumoniae be prevented?
- Polysaccharide vaccine (Pneumovax 23)
- Capsular polysaccharide conjugated to protein (Prevnar-13): works better in children
Indicated for peole at risk (young, old, immunocompromised, chronic lung disease)
A Mycoplasma pneumoniae pneumonia may cause unusual manifestations such as….
- Hemolytic anemia
- Neurologic abnormalities (encephalitis)
- Skin rashes
How is pneumonia caused by Mycoplasma pneumoniae differ from pneumonia caused by S. pneumoniae and H. influenzae?
M. pneumoniae pneumonia…
- More gradual in onset
- Cough is non-productive
- Chest x-ray is non lobal
- More mild
What media should you use to grow H. influenzae?
Chocolate agar
- Requires hemin and NAD
- If it grows on sheep blood agar, it is not H. influenzae
What is the treatment for H. influenzae infection?
- Cephalosporins, trimethoprim-sulfamethoxazole, macrolides, amoxicillin/clavulanic acid, quinolones
- Penicillins not effective against beta-lactamase producing strains
Community-acquired pneumonia with hemolytic anemia, many neutrophils, and less severe symptoms is most likely caused by which bacteria?
M. pneumoniae
Clamydia pneumoniae
Gram stain:
Intracellular or extracellular:
Gram stain: gram negative but does not take up gram stain
Intracellular or extracellular: Obligate intracellular
Describe the clinical presentation of s. pneumoniae infection
- Fever
- Productive cough - rusty colored sputum
- Pleuritic chest pain
- Diminshed respiratory excursion
- Abrupt onset
Corynebacterium diphtheria
Gram stain:
Shape:
Gram stain: Gram positive
Shape: Bacilli (club shape)
Which bactera cause pneumonia with lobar infiltrates on chest x-ray?
- S. pneumoniae*
- H. influenzae*
Which of the following is a cause of life-threatening epiglottitis?
A. Streptococcus pneumoniae
B. Haemophilus influenzae
C. Mycoplasma pneumoniae
D. Legionella pneumophila
B. Haemophilus influenzae
Streptococcus pneumoniae
Gram stain:
Shape:
Hemolysis:
Gram stain: Gram +
Shape: “lancet-shpaed” diplococci
Hemolysis: alpha-hemolytic
What will you see on H. influenzae CXR?
Lobar infiltrate
What are the determinants of pathogenicity of H. influenzae?
- Polysaccharide capsule
- 6 types
- Antiphagocytic
- We can develop protective immunity against the capsule
- => There is a vaccine that works!
What will you see in a chest x-ray of somebody infected with S. pneumoniae?
Lobar infiltrates
What are the determinants of pathogenicity of s. pneumoniae?
- Capsule
- Pneumolysin
- Degrades hemoglobin
- Activates complement
- May form pores in human cells
All of the following are said to cause an atypical pneumonia EXCEPT:
A. Streptococcus pneumoniae
B. Chlamydia pneumoniae
C. Mycoplasma pneumoniae
D. Legionella pneumophila
A. Streptococcus pneumoniae;
Which organism causes cold hemagglutinins?
- H. influenzae
- S. pneumoniae
- M. pneumoniae
c. M. pneumoniae
Which bacteria most likely caused this?
Corynebacterium diptheria
How does s. pneumoniae spread?
Human to human via droplets
Hospital acquired (HAP) pneumonia is pneumonia that occurs ________ hours after hospitalization
Hospital acquired (HAP) pneumonia is pneumonia that occurs >48 hours after hospitalization
Ventilator-associated pneumonia (VAP) is pneumonia that occurs ______ hours after mechanical ventilation
Ventilator-associated pneumonia (VAP) is pneumonia that occurs >48 hours after mechanical ventilation
Unencapsulated strains of H. influenzae can infect _______.
Why?
Unencapsulated strains of H. influenzae can infect adults and children.
We cannot develop protective immunity if there is no capsule - no capsule = no antigens to make antibodies against
Which bacteria has protein adhesin P1? What does it do?
Mycoplasma pneumoniae
Allows the bacteria to bind tightly to respiratory epithelium
Who gets streptococcal pneumonia?
Anyone - healthy or immunocompromised
Especially people who recently had the flu
Enterobacteriaceae
Gram stain:
Shape:
Anaerobic/aerobic:
Gram stain: gram -
Shape: rod
Anaerobic/aerobic: facultative anaerobes
Haemophilus influenzae
Gram stain:
Shape:
Gram stain: gram negative
Shape: small, gram-negative coccobacilli
