Respiratory Flashcards
Lower resp. tract GS acceptilibity
Less than 10 squamous epithelial cells + more than 25 PMN cells
Upper resp. tract
Throat, nasopharynx, ear, sinus
Normal flora
Pathogens
Pharyngitis
S. pyogenes (Group A)
Less common: Group C beta, group G beta, and Arcanobacterium, Fusobacterium necrophorum.
Required R/O: C. diphtheriae, N. gonorrhoeae
Sinusitis & Otitis
S. pneumonia, H. influenzae, M. catarrhalis, S. aureus, S. pyogenes, GN bacteria
Epiglottitis
H. influenzae
Lower resp. tract
Shouldn’t have normal flora (may be contaminants)
Pathogens: S. pneumonia, H. influenzae, Group B strep in neonates, GNR, S. aureus, Legionella
Nosocomial pathogen
Pseudomonas, Klebsiella, other Enterobcteriae, S. aureus, M. catarrhalis, Anaerobic
Rapid antigen test for throat
- Detect Group A Strep: PDX test
- Sensitivity: 83%, high specificity: 100%
- Negative RADT should be confirmed by culture
Acute pharyngitis pathogens
- Strep beta-hem Group A, C (large colon), G (food-borne):
- Arcanobacterium
- Neisseria gonorrhoeae
Arcanobacterium
GPR Pharyngitis assoc. with rash. Extracellular toxin: phospholipase D, hemolysis Catalase, Urease: neg Inhibit hemolysis of S. aureus
Strep beta-hem group
Pharyngitis
Group A, C (large colon), G (food-borne)
GPC in pair, cat: neg, latex agglu.
Neisseria gonorrhoeae
Pharyngitis + tonsillitis: mostly asymptomatic
Transport system: Amies gel (org. very sensitive to dry and temp)
Culture: selective media, e.g. Thayer-Martin, Martin-Lewis, or CA
N. meningitidis
Flora of nasopharynx and oropharynx
Required report when: abundance or special request (epidemic)
Work up in a BSC
Throat normal flora
S. aureus, H. influenzae, S. pneumoniae, M. catarrhalis, enteric GNR (when they’re low level)
Corynebacterium diphtheriae
- Tinsdale agar: black colonies with brown halo
- Cystine-tellurite: gray to black
- Loeffler’s: produce metachromatic granules
- ID test: GPR, methylene blue stain from Loeffer’s (metachromatic look like granules)
Urease: neg, Nitrate reduction; pos, Sugar fermenter.
Sputum & Endotracheal suction culture
GS: columnar epithelial cells Pathogen: when predominant R/O: S. pneumonia R/O Cryptococcus neoformans Only ID when predominant: S. aureaus, GNR Always ID: Mycobacterium, Nocardia, mold
Saprophytic Neisseria
Colonies: beige to yellow, opaque
Oxidase: pos
Moraxella catarrhalis
CTA: all neg Catalase: pos Oxidase: pos Butyrate: pos Nitrate: pos DNAse: pos
Normal flora oropharyngeal
Anaerobes, Beta-hem strep (except A, C, G) Coagulase-neg Staph Diphtheroids Lactobacillus Micrococcus Neisseria spp. Rothia mucilaginous Viridian strep. (more)
M. tuberculosis condition & media
Primary nutrient required: Lipid
Egg-based: Lowenstein-Jensen
Serum-based
Broth media incubated and read by instruments
Temp: 35-37C (30-42C)
5-10% CO2
Time: 6-8 weeks –> Read twice per week for 1st 2 weeks and once per week
Direct detection of M. tuberculosis
NAAT: amplify and detect DNA or rRNA, no distinguish live or dead bacilli, no following therapy.
Photochromogen
Produce pigment when light exposure
M. kansassi
Scotochromogen
Produce pigment w/o light exposure
M. avium complex
Non-chromogen
No pigment, M. tuberculosis, M. abscessus (rapid grower)
