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
