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41 Cards in this Set
- Front
- Back
Quality Score |
A score given to a specimen (0-3) based on the number of squamous cells (a negative indicator of quality) and neutrophils (a positive indicator of quality). Specimens in which the number of squamous cells is equal to the number of neutrophils are not processed. (Q = 0) |
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Q score = 0 |
Not representative of lower respiratory tract secretions. Specimen rejected |
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Q score = 1 |
Poor quality specimen |
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Q score = 2 |
Acceptable quality specimen |
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Q score = 3 |
Good quality specimen |
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Gram Stain (Definition) |
Stain used to classify bacteria based on their cellular morphology and Gram reaction. It is used to assess the quality of clinical specimens and for rapid presumptive diagnosis of infectious agents. Specimens stain either Gram positive or Gram negative depending on their cell wall. |
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Direct Smear |
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Secondary Smear |
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Gram Stain Reagents (In order) |
Crystal Violet (Primary Stain) Gram's Iodine (Mordant) Alcohol-Acetone Decolorizer Safranin or Carbol-Fuschin (Secondary Stain) |
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Gram Positive (Color, cell wall...) |
Stain Purple. Thick peptidoglycan layer and large amounts of teichoic acids; unaffected by decolorization. |
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Gram Negative (Color, cell wall...) |
Stain Pink or Red. Single peptidoglycan layer attached to an asymmetric lipopolysaccharide-phospholipid bilayer outer membrane interspersed w/ protein; the outer membrane is damaged by decolorizer, allowing initial stain to leak out and be replaced by counter stain. |
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Cocci |
Spherical; May appear singly, in pairs (diplococci), in chains (streptococci), or in clusters (staphylococci). |
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Bacilli |
Rod-shaped; May appear singly or in chains. |
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Coccobacilli Filamentous bacilli Fusiform bacilli Pleomorphic rods |
Very short rods Very long rods Have tapered, pointed ends Multiple shapes |
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Pure culture |
A lab culture containing a single species of organism. |
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α hemolysis |
Incomplete hemolysis; Colonies surrounded by a zone of greenish discoloration. |
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ß hemolysis |
Complete lysis of RBC's; Colonies surrounded by clear zone. |
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Γ hemolysis |
Non-hemolytic. |
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S. aureus |
- Gram positive; spherical cocci in clusters - Small, circular, grey on BAP, ß hemolytic - May appear 'golden' on BAP |
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Streptococcus pneumoniae |
- Gram positive; lancet shaped diplo-cocci - Small, circular, brown-grey on BAP; α hemolytic |
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Streptococcus pyrogenes |
- Gram positive; spherical cocci in chains - Punctiform, circular, cream on BAP; ß hemolytic |
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E. Coli |
- Gram negative; med rods - Moderate, circular, grey on BAP; ß hemolytic; Lactose fermenter on MAC |
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Pseudomonas aeruginosa |
- Gram negative; thin rods - Moderate, circular, curled, shiny metallic on BAP; ß hemolytic; Translucent grey on MAC |
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Neisseria spp. |
- Gram negative; bean shaped diplo cocci - Grows on CHOC, ML and MTM |
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Corynebacterium spp. |
Gram positive but looks variable; Pleomorphic, club-shaped bacilli in chinese letter arrangement |
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Bacillus spp. |
Gram positive; Med to large square-ended bacilli; Spores not visible in direct smears; May stain gram variable or negative w/ age. |
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Lactobacillus spp. |
Gram positive; Med, straight, round-ended bacilli; May form chains |
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Acinetobacter spp. |
Gram negative; Cocci in pairs; occasionally coccoid, bacilliary (A. baumanii), and filamentous forms |
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Haemophilus spp. |
- Gram negative; Tiny coccobacilli or pleomorphic rods - Doesn't grow on BAP, Grows on CHOC |
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Klebsiella pneumoniae |
- Gram negative; rods - Small, circular, grey on BAP; α hemolysis; Lactose fermenter on MAC |
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Enterococcus spp. |
- Gram positive oval in pairs or short chains - Small, circular, white on BAP; α hemolytic |
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Cryptococcus nerformans |
Gram positive large cocci, granular/abnormal with polysaccharide capsule surrounding (halo) |
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Urine (expected pathogens and media) |
- GP and GN bacilli - BAP, MAC/EMB, CNA |
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Stool |
- GN bacilli - MAC, HEK/XLD |
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Wound |
- GP and GN bacilli - BAP, MAC/EMB |
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Tissue |
- Any organism - BAP, CHOC |
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Fluid |
- Any organism - BAP, CHOC |
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Lower respiratory |
- GP, GN bacilli, and Heamophilus influenzae - BAP, MAC/EMB, CHOC |
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Throat |
- Streptococcus pyrogenes - BAP |
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Genital |
- Neisseria gonorrhoeae - ML/TM, CHOC |
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Specimens that require CO2 (4) |
Fluid, Lower respiratory, Throat, Genital |