Bacterial Pneumonias 1 Flashcards
What are 4 causitive agents of typical pneumonia?
S. Pneumo, H. Flu, K. Pneumoniae, S. Aureus
What are the three zoonotic pathogens of atypical pneumonia?
Chlamydia psittaci, francisella tularensis, coxiella burnetti
What are the three non-zoonotic pathogens of atypical pneumonia?
Chlamydia pneumoniae, mycoplasma pneumoniae, legionella pneumoniae
How does the typical bacterial pneumonia present?
Sudden onset, appears sick, higher fever (over 103), Chills and shaking, productive cough, frequent pleurisy, well-defined consolidation on a CXR, SOB
How does the atypical bacterial pneumonia present?
Gradual onset, appear well, lower fever (less than 103), Patchy infiltrates, non-productive cough, patchy infiltrates (diffuse), body aches, diarrhea, abdominal pain
What are the characteristics of S. Pneumo?
Gram positive lancet shaped diplococcus
alpha hemolytic
optochin sensitive
encapsulated=virulent
What is the major reservoir for s. pneumo?
asymptomatic carriers due to normal flora
What is the major virulence factor for s. pneumo, what is it the basis for, and how does it have its action?
The capsule, basis for serotyping and anti-pneumococcal vaccines, inhibits phagocytosis which interferes with complement activity by preventing opsonization of the bacteria by C3b
What are two virulence factors utilized by s. pneumo to enhance protection?
IgA protease, hydrogen peroxide (apoptosis in host cells and elimination of competing bacteria)
What are the two virulence factors that contribute to the binding capacity of s pneumo?
Pili (activate production of large quantities of TNF and help colonize UR tract) and surface proteins (choline binding proteins)
What is the role of peptidoglycan-teichoic acid complex in producing virulence for s. pneumo?
it is a potent immune modulator so it illicits a significant immune response
What is the virulence factor of s pneumo that activates complement by forming transmembrane pores?
Pneumolysin
What effect do neuraminidase and hyaluronidase have on s pneumo virulence?
They chew away tissue matrix to embed itself into the tissue to get away from abx
What is autolysin released in response to? What does it do as a virulence factor for s pneumo?
in response to abx tx and stationary phase as an attempt to dampen the host immune response by causing lysis of pneumococcus and release of pneumolysis and host cell apoptosis
What is a way to presumptively ID s. pneumo?
optochin sensitivity
What is a way to confirm s. pneumo?
bile solubility– bile will lyse s. pneumo but not other alpha hemolytic strep
What is used to observe s. pneumo capsules?
A Quellung reaction (agglutination test)
What is the name of the test that looks for s pneumo specific rRNA and is quick, accurate, and relatively inexpensive?
Genetic probe test
What is the DOC for s. pneumo?
PCN G, but it is becoming increasingly resistant so may have to replace with vancomycin and watch blood levels
What population is the 23-valent s. pneumo vaccine indicated for?
65+ and persons with predisposing factors
What population is the 13-valent s. pneumo vaccine used for?
children 6 years and under, it includes 75% of strains of penicillin-resistant s. pneumo
You find a non-motile, gram negative bacillus with a thick slimy capsule. What is it most likely to be and what populations should you watch out for it in?
Klebsiella pneumoniae,
ALCOHOLICS, DM, and homeless population
Where is Klebsiella found?
It is considered normal intestinal flora, but is important cause of nosocomial infections
What is the primary virulence factor for Klebsiella pneumo?
polysaccharide capsule which prevents MAC-mediated lysis
What is another virulence factor of klebsiella? What does it help to do?
adhesins, which are receptor specific and either fimbrial or non-fimbrial; once patient aspirates, it helps cause aggressive necrotizing CAP with lots of blood and severe illness with rapid onset.
What is the CP of Klebsiella? What is the outcome?
Acute onset of high fever and a productive cough with a thick, blood tinged, CURRENT JELLY sputum, often absess formation, cavitation, and pleuritic chest pain; Often fatal, even with antibiotic treatment
What is the treatment for Klebsiella?
AG+3rd gen. cephalosporin+fluoroquinolone
What organism is the smallest of free-living bacteria, lacks cell walls, stains poorly, creates a “fried egg” appearance in culture, and is pleomorphic in shape?
Mycoplama pneumo
What is the CP of mycoplasma pneumo?
non-productive cough that lasts 1-2 months, fever, crackles, headache, and chest pain, RELAPSE IS COMMON
What allows mycoplasma pneumo to go undetected? What is one other virulence factor?
Sterol appears like host membrane, H2O2 production
What is the target population of mycoplasma pneumoniae?
Ages 5-20
What is unique about the colonies of sputum culture from mycoplasma?
They are mulberry colored
What test is used to detect mycoplasma antibodies that bind to the I antigen on the surface of RBCs at 4 degrees C?
Cold agglutinin assay
What is the DOC for mycoplasma?
Azithromycin/tetracycline
you have a tiny, non-motile, coccoid shaped bacteria that must exist as an intracellular parasite. It is gram negative. What is it?
Chlamydophila pneumo
What are the two forms of Chlamydophila pneumo?
Elementary bodies (EB)= infectious form Reticulate bodies (RB)=intracellular form (EB--RB--EB---RELEASE)
What is the CP of chlamydophilia?
persistent, non-productive cough and malaise, usually unilateral lower lobe involvement
What age group is most affected by chlamydophilia pneumo?
age 60+
What two causitive agents of atypical pneumonia will not produce very long lasting immunity?
Mycoplama and chlamydophilia
How long does Chlamydophilia infection last for?
weeks to months
What bacterium contains LOS in cell wall?
H. flu
Where is nontypeable H. Flu found?
In normal flora, in debilitated hosts such as asthma, COPD, smoking, immunocompromised pts
What are the virulence factors of H flu?
PRP to resist phagocytosis by PMN, NA and IgA protease, LOS layer
What type of H flu causes infection and disease?
Non-typeable (non capsular) due to an imbalance. They contain adhesins to bind mucins in respiratory tract
What does LOS cause in the host cell?
Loss of cilia, inflammation, and sloughing off of damaged cells
What type of agar is H Flu grown on?
Chocolate Agar
What is the name of the phenomenon where blood agar can grow H flu?
Satellite pneomenon
After chocolate agar growth, what other tests on H Flu will be positive?
Catalase and oxidase, then more serology to determine if capsule is present
What is the LAT, what is it used to detect, and why is it beneficial?
Latex Particle Agglutination test, H Flu capsule, you don’t need viable bacterium, just antigen!
Pertaining to Legionella, which species causes 90% of human infections? What serogroup?
Pneumophilia, serogroup 1
You have a thin, pleomorphic, gram-negative bacillus with fimbriae, a single, polar flagellum, and long strands. What is it most likely?
Legionella pneumophila
What tests are positive in legionella pneumophila?
B lactamase producer, catalase, and oxidase
How does infection by legionella occur?
Through aerosol inhalation, opsonization with C3b, phagocytosis, then survival intracellularly by inhibiting PHAGOLYSOSOME FUSION. Replication inside phagosome, then the host cell is killed and toxic enxymes are released
What is the CP of Pontiac Fever and which microbe causes it?
Fever, chills, malaise, myalgia, HA, NO SIGN OF PNEUMONIA, self limited, usually does not need treatment, caused by Legionella
What is the CP of Legionnaires’ Disease caused by Legionella?
A SEVERE, ACUTE, ATYPICAL PNEUMONIA with a high no tx mortality rate. Fever, chills, dry/nonproductive cough, HA, GI AND NEURO COMMON.
What type of pneumonia results from Legionnaires’ disease?
Acute, fibropurulent, necrotizing pneumonia which quickly restricts airfow
You take a shower in a locker room of a football stadium in Illinois and now you are really sick. What agent caused it and where does it replicate?
Legionella pneumophilia, in protozoans, is then transmitted through aerosols SPORADICALLY
What pneumonia should anyone with compromise in pulmonary and/or immune function be exceptionally at risk for?
Legionella
What is the gold standard of diagnosis for legionella? What is another type of test used to check for antigen?
Buffered Charcoal Yeast Extract (BCYE); EIA urine antigen test
You identify a gram negative, motile bacillus that is blue tinged. What is it most likely?
Pseudomonas
What are the key virulence factors of pseudomonas and how do they make their impact?
Pyocyanin=ROS production for apoptosis
Exotoxin A=ciliastasis and immune suppression
Elastases A&B=destroys lung tissue
Alginate: mucoid polysaccharide to inhibit mucociliary escalator and form a glycocalyx
LPS=endotoxin to produce shock, DIC, etc
How is pseudomonas transmitted?
Via fomites (plants, fruits, hands)
What is the most common cause of death of CF patients? What is the second leading cause of infection in burn patients? What makes it so virulent?
PSEUDOMONAS, A significant break in normal defense
What type of media supports growth of pseudomonas? What will it produce?
BAP & MacConkey; blue-green pigment +/- fluorescence, “fruity smell”
What is the treatment of pseudomonas NP? What should be avoided??
4th generation cephalosporin (cefepime)+ Levofloxacin. BROAD SPECTRUM SHOULD BE AVOIDED!
