Laboratory Diagnosis of Bacterial Infections Flashcards
The diagnosis of a microbial infection begins with an assessment of ________ and _______ features, leading to the formulation of a diagnostic hypothesis.
clinical and epidemiologic
Laboratory diagnostic methods
______________ examinations
_______
_________ reactions
______ detection, and _____ detection (______).
____________ assays that allow direct detection of genomic components of pathogens
Direct microscopic
Culture; Biochemical
Antigen; antibody; serology
Nucleic acid amplification (NAA)
Site of sampling
Blood
Sterile or non sterile
Sterile
Site of sampling
Cerebrospinal fluid (CSF)
Sterile or non sterile
Sterile
Site of sampling
Sterile
Body fluids (______ and ______ )
Peritoneal and pleural
Site of sampling
Non-sterile (________)
_____tract
Ear, eye and mouth
____(wound and abscess)
______(mid-stream)
Feces
normal flora
Respiratory
Skin; Urine
Microscopy
Could be :
• Unstained preparations
• “________ “
Or
•____________ eg for _____
Wet prep
Dark-ground illumination ; syphillis
By Microscopy
Could be :
•_______ preparations
• _______ preparations
Unstained
Stained
Microscopy
Could be :
• Stained preparations
•______ -stain
•______ stain
• ________
Gram
Acid-fast
Fluorescence
Fluorescence (stained microscopy preparation)
Could be :
•______, e.g. _______
Or
•_______
Direct; auramine
Immunofluorescence
Types of stains
_______ stains
_______ stains
________ stains
Simple
Differential
Structural
Types of stains
Simple stains
-how many dyes are used??
-reveals _____,______, and _____
one dye Is used
shape, size, and arrangement
Types of stains
Differential stains
-how many dyes are used??
-to distinguish cell types or parts
-examples: ____ stain, ______ stain, and _____ stain
2; uses primary stain and a counter stain
Gram; acid-fast ; endospore
Types of stain
Structural stains
-to __________________________
-eg _______ and _____ stains
reveal certain cell parts
not revealed by conventional methods
capsule and flagellar
Gram stain
Gram stain uses a series of stains or dyes, _____ stain eg _____, _____ is added as ____ and _____ with _____ and _____ with ______ or _____.
primary; crystal violet
Lugols iodine; mordant
decolorization; acetone
counterstain; saffron or methyl red
Gran stain
Each dye allows to stay for _________ before ______ but ______ is applied as fast as to decolorize.
Then Drain the slide to dry.
Followed by inspection under a light microscope to detect and identify bacteria as Gram-positive or Gram-negative.
30-60seconds
gentle washing; acetone
A Gram stain can be done on the ______ , but it is usually done on ________ after transferring a _____ of bacteria from the _______ to a glass microscope slide
original sample
cultured bacteria
colony
agar plate
A Gram-positive bacterium appears _____ or _____ due to ______ dye adhering to the cell wall.
A Gram-negative bacterium appears _______, as it is counterstained with a red dye such as ________ or ____
blue or purple
crystal violet
red or pink
saffron or methyl red.
The Gram stain also identifies the bacterium’s _____ and ____
shape and behaviour.
Cocci are ____ in shape Bacilli are _____-shaped
Some bacteria form clusters whilst others form chains
round
rod