Becterial Pneumonias Flashcards
Bacterial pneumonia most common pathogens
All of these pathogens enter the respiratory system via inhalation, aspiration of systemically via blood.
Streptococcus pneumonia
- most common in adult
Haemophilus influenza type B
- most common in adult
Legionella pneumothorax
Klebsiella pneumoniae
Pneumocystis jirovecii (fungal pathogen usually seen only in immunosupression)
Mycoplasma pneumoniae
- more common in adults
Note: staph aureus does not produce pneumonia
Is most pneumonia viral or bacterial?
Viral is far more common
This is especially true in children
- RSV and HRV combine for almost 50% of all childhood pneumonia
Hospital pneumonia catagories
Based on how they got the disease (all tend to be more rare infections)
1) Are HIV positive
- pneumocystis jiroveci
- mycobacterium
2) immunocompromised through drugs
- aspergillosis
- mycobacterium
3) ventilation assistance
- kiebsellia
- serrata
- aeruginosa
What is imperative to do when you suspect problematic pneumonia (bacterial)
- Gram stain
- culture the sputum that is present
- serology
Also begin empirical treatments until specific pathogen is known
Complement fixation test
Determines what antibodies a patient has in their body
Procedure:
1) patient serum is mixed with specific pathogenic antigens
2) compliment and RBCs are then added tot he mixture
3) if patient DOES have antibodies = compliment binds to antigen/antibody complex and NO RBC LYSIS/ reactive
4) if patient DOESNT have antibodies = compliment binds to the RBC and RBC LYSIS/nonreactive
Types of ELISA refresher
Direct ELISA
- used when you want to know if a patient has a specific antigen
- mix patient sample with primary antibody conjugate that is labeled fluorescently
Indirect ELISA
- used when you want know if a patient has a specific antibody
- mix patient sample with secondary antibody conjugate (artificial antibody that is labeled and is made to bind to natural antibodies)
Sandwich ELISA
- use when you want know if a patient has a specific AB:AG complex
- mix patient sample with secondary antibody conjugate (artificial antibody that is labeled and is made to bind to natural AB:AG complexes)
Mycoplasma pneumonia
Primary cause of “walking pneumonia”
- Pulse-temperature dissociation is present (fever w/ no increased pulse) w/ very mild symptoms
Lack cell walls (cant use B-lactams)
Smallest free-living organisms
need PCR for definitive diagnosis
Hard to culture (use eatons agar if you must)
Generates own ROS and use gap junctions to move into cells
- Can show hemolytic anemia*
Stevens-Johnson syndromes
Widespread Epidermal damage caused by the production of self-reactive CD-8 cytotoxic T-cells
Causes:
- mycoplasma pneumoniae
- HSV
- exposure to certain medications if you have hypersensitive (or not sometimes)
Hemolytic anemia
Body mistaken creates self-reactive antibodies to its RBCs in cold temperatures
- diagnosed via cold-agglutination testing
Is often associated with mycoplasma pneumoniae and legionnaires diseases
Streptococcus pneumoniae specifics
Accounts for 60% of all bacterial pneumonia
- most common pathogen in secondary infections after viral infections
- high rates in alcoholics and drug abusers
- produces rusty sputum (mild hemoptysis)
Gram positive diplococci w/ capsule
Forms biofilms
A-hemolytic
- partially hemolytic (looks green)
Tests:
- optochin (+)
- catalase (-)
- coagulase (-)
- pneumolysin (+)
- quellung (+)
Complications in streptococcus pneumoniae
Bacteremia
Sepsis
Meningitis
Pneumococcal endocarditis
Legionnaires disease specifics
Legionella pneumophila is the causative agent
- most common in thick,moist air infections (poor AC units, Hot tubs, showers etc.)
Aerobic intracellular pathogen
Gram-negative and stains poorly
- need to use silver staining W/ BYCE (buffer charcoal yeast extract) agar
- BYCE has no hydrogen peroxide (since hydrogen peroxide is instant death to this bacterium)
Major virulence factor = metalloprotease secretion
- inhibits phago-lysosome and breaks down zinc
- to best detect use urinary antigen tests*
Pontiac fever and atypical legionella pneumonia
Both are atypical forms of pneumonia caused by legionella pneumophila
Atypical:
- severe pneumonia w/ little to no inflammation of the bronchioles/upper airways
- hyponatremia is common
- not self-limiting
Pontiac fever
- less severe pneumonia that only shows a fever and arthralgia
- self-limiting
Pseudomonas aeruginosa specifics
- ALWAYS GROWS GREEN*
- also shows a grape-like odor
Gram (-) rods
Found in all places, especially in hospitals
- most patients are asymptomatic, and usually only express symptoms if they are immunosuppressive
VERY common in CF patients and people w/ ventilator assistance
- roughly 80% of all CF patients have pseudomonas by age 25 in their lungs
- if untreated causes necrotizing pneumonia
Tests:
- catalase (+)
- oxidase (+)
- hemolysin (+)
- leukocidin (+)
- elastase (+)
Virulence factors in pseudomonas aeruginosa
Exotoxin A
- inactivates elongation factor 2 in hosts which halts cell protein synthesis
Mucous exoploysaccharide
- helps form biofilms
Phospholipids C
- lysis of cell membranes
Presentations of pseudomonas aeruginosa
Sepsis
Soft tissue wounds
- will look green w/ grape smell
- looks gangrenous most of the time
- very high incidence in burn wounds
Eyes
- causes extreme rapid pain if in the eyes
- vision loss will occur if untreated
Endocarditis
Haemophilus influenza (type B)
Gram (-) rod
DOESNT CAUSE FLU
- type A does this
Only grows on chocolate agar w/ factors V and X present
Can produce epiglottis, meningitis and otitis media on top of pneumonia
- rates are stupid low due to vaccines
Klebsiella pneumoniae specifics
Gram negative anaerobic rod w/ capsule
Found in flora of the mouth and GI normally and doesn’t actually cause damage unless it gets into the wrong places or you are any of the following susceptible populations - alcoholic - diabetic - immunocompromised (Because of this its very rare)
- shows currant jelly sputum (bright red mucus sputum infections*
- also may show lobar pneumonia w/ lung abscesses
Tests: - urease (+) - lactase (+) on Macconkey agar - Beta-lactamase (+) (cant use B-lactams, must use cephalosporins)
Moraxella catarrhalis specifics
Aerobic Gram (-) diplococci
Not common except in the following
- lung cancer
- COPD
- children younger than 2
- elderly (>65yrs)
- immunosupression
Causes pneumonia and URIs that spreads via respiratory droplets
Burkholderia cepacia (BCC)
Gram negative rods w/ capsule
Is catalase positive
Most commonly found in CF patients
- this is due to it being the #1 most common co-infection w/ pseudomonas aeruginosa infections
Very dangerous and rapidly mutates
- very antibiotic resistant
- this often tested in CF patients just regularly*
Pneumocystis jirovecii
Fungus that likes to live in alveoli
- always asymptomatic in healthy patients
Dangerous in HIV cases
Have foamy alveolar casts w/ disc-shaped yeast upon microscopic examination
Shows ground glass opacities on CTs
Symptoms (very rapid onset)
- tachypnea
- fever
- cough
- respiratory distress
Zoonotic pathogens that can cause pneumonia
Chlamydia psittaci
- spread by parrots and pigeons
- have elementary (infections) and reticulate (replication) bodies
Histoplasma capsulatum
- spread via rare fungus on animals
