8. Atypical Pneumonias Flashcards
Genus of cell wall deficient bacteria
Mycoplasma
Aspergillus wet prep stain
Lactophenol Cotton Blue stain
Old and current method of M. pneumoniae lab detection
Past: complement fixation (CF)
Current: ELISA
Difference between ZN and Kinyoun stain?
ZN = requires heat
Kinyoun = cold method of ZN w/ higher phenol and basic fuchsin concentration
Requires cell lines to culture
Chlamydophila pneumoniae
Most common method of diagnosing M. pneumoniae
ELISA
Primary stain, decolourizer, and counterstain for Kinyoun acid fast?
Primary = carbol fuchsin
Decolourizer = 3% acid-alcohol
Counter = methylene blue or brilliant green
3 second line M. tuberculosis drugs
Kanamycin
Amikacin
Capreomycin (injectable)
Which organism? Buffered charcoal yeast extract agar
Legionella pneumoniae
Counterstain for acid-fast stains
Methylene blue or Brilliant Green
No culture options currently exist for this organism
Pneumocystis jiroveci
Mycoplasma pneumoniae atmospheric requirements
Increased moisture but NOT increased CO2
This organism can target any organ system; most serious infections seen in the elderly, smokers, alcoholics
Legionella pneumophila
3 types of specimens that may be sent for Aspergillus culture
- Sputum
- BAL
- Lung biopsy
How does the lab detect M. tuberculosis
Acid-Fast stain
2 culture media for M. tuberculosis
Lowenstein-Jensen
Middlebrook
Organism found in hospital showerheads
Aspergillus spp.
How are potential Legionella specimens treated prior to media inoculation to reduce normal URT colonizers
Heat or acid treatment
Which organism? SP4 broth and agar
Mycoplasma pneumoniae
Often implicated in “walking pneumonia”
Mycoplasma pneumoniae
Organism w/ intrinsic resistance to penicillins, cephalosporins, aminoglycosides
Legionella pneumophila
Thin, faint gnb that may be missed in direct smears
Legionella
Fluorescent acid-fast stain that attaches to the mycolic acid on cell walls
Traunt
Which organism? Cell culture w/ HeLA229 cells
Clamydophila pneumoniae
5 first line M. tuberculosis drugs
Isoniazid = INH Rifampin Pyrazinamide = PZA Ethambutol - loss of colour vision Streptomycin - ototoxic
Treatment may be switched to this antibiotic once C. pneumoniae is confirmed to be the causative agent
Doxycycline
What colour do AFB organisms appear as?
Dark pink/red
Organism w/ microscopic fried egg colony appearance
Mycoplasma pneumoniae
Organism that may be detected by fungi-fluor (Cellufluor) or Calcofluor White WITHOUT KOH
Pneumocystis jiroveci
Unlike other pneumonias, infection by this organism rarely develops serious complications
Mycoplasma pneumoniae
How are M. tuberculosis sputums processed?
also applies to urines, skin specimens
Liquefactionated and decontaminated (to kill most bacteria that aren’t M. tuberculosis)
Not often implicated in human disease; species are usually inhibited at 37C
Penicillium
Which organism? Lowenstein-Jensen media
Mycobacterium tuberculosis
Most often used as a first line antifungal
Voriconazole
Typical abx treatment for Legionella
Macrolides (erythromycin, clarithromycin, azithromycin)
Abx to treat Legionella?
Macrolides or fluoroquinolones
Will NOT grow on BAP/CHOC but will grow on BCYE
Legionella pneumophila
Used extensively as a last resort drug in “extensively drug resistant TB” (XDRTB)
Cycloserin
Once a rare form of pneumonia in neonates but now it’s almost exclusively found in the immunocompromised
Pneumocystis pneumonia (PCP)
Aspergillus specimens may be examined by this direct exam method
KOH prep w/ calcofluor white stain
Look for fungal elements
How are M. pneumoniae specimens prepared for media inoculation?
Filtered to eliminate competing yeast and bacteria
AKA Traunt acid-fast stain
Auramine-Rhodamine
Difference between Legionnaire’s disease and Pontiac fever?
Legionnarie’s = a pneumonia
Pontiac fever = a systemic infection, non-pneumonic
____________ are found in no more than 50% of M. pneumoniae infections
Cold agglutinins
Atmosphere required for M. tuberculosis
10% CO2
2 forms of legionellosis
- Legionnaire’s disease
- Pontiac fever
Are actually 2 forms of legionellosis
Media for this organism must contain glucose and/or arginine, serum for cholesterol, and antibiotics to prevent overgrowth by other bacteria
Mycoplasma pneumoniae
3 components of the Lactophenol Cotton Blue stain and their purposes
Phenol - kills live organisms
Lactic acid - preserves fungal structures
Cotton Blue Stain - stains chitin in fungal cell walls
M. pneumoniae is the only mycoplasma that is positive for this specific identification test
Hemadsorption
Associated with water and water systems, is chlorine resistant, survives a variety of temps
Legionella pneumophila
Infective and replicative form of Chlamydophila
Infective = elementary body (EB)
Replicative = reticulate body (RB)
