Pneumonias Flashcards
1
Q
Streptococcus pneumoniae
A
- Gram positive cocci, catalase negative
- alpha hemolytic, optochin sensitive, lancet shaped diplococci and lysed by bile
- Reservoir in upper respiratory tract
- Capsule makes it dangerous in splenic patients and causes a positive Quelling reaction
- Most common cause of typical pneumonia, especially in pts in their 60s; also the most common cause of adult meningitis
2
Q
Haemophilus influenzae
A
- Gram negative pleomorphic rod
- Requires growth factors X and V for growth on nutrient or blood agar
- Has a polysaccharide capsule
- causes meningitis commonly in unvaccinated children aged 3 months to 2 years
- Can cause bronchitis, pneumonia and epiglotitis in unvaccinated toddlers (children present with “catchers stance” to aid in breathing)
3
Q
Moraxella catarrhalis
A
- Gram negative diploccous that is a normal upper respiratory tract flora
- Moset common cause of otitis media and sinusitis
- Most strains produce a beta lactase
4
Q
Staphylococcus aureus
A
-
5
Q
Klebsiella pneumoniae
A
- Gram negative rods that have a capsule
- causes the creation of a currant-jelly sputum
- Can cause UTIs in association with catheters
- Oxidase negative and forms mucoid, lactose fermenting colonies on MacConkey agar
- Endotoxin causes septicemia
- Pneumonia of those who are alcoholics
6
Q
Pseudomonas aeruginosa
A
- Gram negative rod that is oxidase positive
- Aerobic (non-fermenting), pyocyanin pigment (blue green) and fluorescein expression
- Can present with a grape like odor on culture and has a slime layer
- Has non-lactose fermenting colonies on EMB or Mac Conkey agar
- Ubiquitous in water
- Exotoxin ADP ribosylates eEF-2 inhibiting protein synthesis and the liver is the primary target
- Can cause hot tub folliculitis, eye ulcers, and cellulitis in burn patients (blue-green puss)
- Can be a major problem as a cause of typical pneumonia in patients with CGD or CF
7
Q
Coxiella burnetti
A
-
8
Q
Mycoplasma pneumoniae
A
- Smallest free living extracellular bacteria; has no peptidoglycan cell wall
- Steroils in its membrane and requires cholesterol for culture
- Fried egg colonies
- Attaches to respiratory epithelium via P1 protein and inhibits ciliary action; then produces hydrogen peroxide, superoxide radicals and cytolytic enzymes which damage the respiratory epithelium
- causes walking pneumonia (most common atypical pneumonia)
- Functions itself as a super antigen
- Causes mulberry shaped colonies on sterol containing media
- Positive cold agglutinins can be a clue but its not diagnostic
9
Q
Chlamydia pneumoniae
A
- Obligate intracellular bacteria with elementary bodies or reticulate bodies seen
- Not seen on gram stain and cannot make its own ATP
- Cell wall lacks muramic acid
- Potentially associated with atherosclerosis
- Transmitted via resp droplets.
- Causes walking pneumonia
10
Q
Legionella pneumophilia
A
- Weakly gram negative organism that usually needs a fluorescent AB test to be visualized
- Requires cysteine and iron for growth in media
- No human to human transition; water organism
- Facultative intracellular (granulomatous response)
- Common problem in smokers over age 55 with high alcohol intake and in immunosuppressed patients (renal transplant patients)
- Associated diseases are common due to air-conditioning systems that are unclean
11
Q
Chlamydia psittaci
A
- Obligate intracellular bacteria with elementary bodies or reticulate bodies seen
- Not seen on gram stain and cannot make its own ATP
- Cell wall lacks muramic acid
- Reservoir in birds (esp parrots) and spread via the dust of dried bird feces
- Causes an atypical pneumonia with hepatitis
- If cough is present the sputum is mucopurulent
12
Q
Burkholderia cepacia
A
-
13
Q
Lobar pneumonia: location, chest X ray, ultrasound, microbiology
A
- Location: Alveoli
- Chest X ray: Dense consolidations, air bronchograms
- US: Consolidation (often extensive
