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
Fluorescence Microscope
Is Modified microscope with ____ source and filter.
Uses dyes that ______ when bombarded with ______ rays- fluorescence
Used in diagnosing infections
An ultraviolet radiation
emit visible light
shorter UV
Culture of pathogenic microbe
Solid media
•________
•_______
Agar plates
Slopes
Culture of pathogenic microbe
Solid media
• Agar plates
For ________
For ________
• Slopes
For _______culture, e.g. _____________ media for TB
Identification; Enumeration
safe long-term ; Lowenstein-Jensen
Culture of pathogenic microbe
• Liquid media ( ____ )
• For _______ or ________
• E.g. _____ cultures
broth
enrichment or maximum sensitivity
blood
Culturing or growing bacteria is most commonly done by inoculating or ____ on ______ from the specimen and exposing them to different conditions.
steaking; agar plates
Bacteria growth depend on the _____ used to culture the specimen, the ____ for _____, and the amount of _____ available.
medium; temperature; incubation
oxygen
Comparison of Selective and Differential Media
In a General-purpose nonselective medium , ____________.
In a Selective medium, ________ grows.
In a General-purpose nondifferential medium, ________________
In a Differential medium, _____________________
All species grow
Only one species grow
All species have a similar appearance.
All species grow but may show different reactions.
Coagulase test
Coagulase is an enzyme produced by certain bacteria that converts ______ to _____ and is observed as _______ in plasma.
The coagulase test differentiates _________ from _______
fibrinogen to fibrin; clumping of cells
coagulase- positive Staphylococcus aureus from coagulase- negative staphylococci.
Catalase test
Catalase is an enzyme that degrades _______ into _______ and _______ .
The bacterial sample is added to a test tube of _______.
The production of _____(____) indicates a positive result.
The catalase test differentiates ___________ from ________
hydrogen peroxide into hydrogen and oxygen.
hydrogen peroxide
bubbles (oxygen)
catalase-positive staphylococci and micrococci from catalase-negative streptococci
Antibiotic Sensitivity Testing
Antibiotic sensitivity testing determines ______________________________
which antibiotics inhibit the growth of the bacteria that have been cultured.
Antibiotic susceptibility testing
This information allows the selection of the most suitable antibiotic to treat a particular infection.
T/F
T
Antibiotic susceptibility testing is used to determine:
1) The ______ of particular antibiotics against particular bacteria
2) Whether the bacteria are ______ to selected antibiotics
3)To identify __________________
effectiveness
resistant
bacterial antibiotic resistance patterns.
Antimicrobial susceptibility testing
___________ test is a standard procedure for assessing antimicrobial activity
While
_________ zones are used to determine an organisms susceptibility to an antimicrobial agent
Disk diffusion
Inhibition
Antimicrobial susceptibility testing
The ____________ procedure is used to assess antibiotic susceptibility with regard to various concentrations
Minimum inhibitory concentration ( MIC)
Serology
Is a branch of immunology dealing with study of ______ interactions in(vivo or vitro?) by different serological tests.
Ag –Ab
Vitro
Serological identification
A-_______ serological tests:
-B- ______ serological tests:
Direct
Indirect
Serological identification
A-Direct serological tests:
- ____________ of unknown organism
-Detection of ________ by using _________
-_________ and _________ of isolated organism
Identification
microbial antigens; specific known antibodies
Serogrouping and serotyping
Serological identification
B-Indirect serological tests:
-Detection of ___________ and _________ ———— (___ and ___ ) by using _____ or ______
specific and non specific antibodies
IgM& IgG
antigens or organisms
Uses of serological identification
•Where organism _________
•To confirm ______
•To measure ______
•Where disease is _________
•To confirm _____
cannot be culture
an isolation
vaccine response
sequelae of infection
PCR
Characteristics of serological identification
(Increased or Reduce?) reliance on culture Faster
(More or Less?) sensitive
(More or Less?) definitive
(More or Less?) discriminating
Techniques adaptable to (all or some?) pathogens
Reduce
More
More
More
All
Various types of serological identification
include:
List 6
Precipitation
Agglutination
Complement fixation
immunofluorescence
Elisa
Western blot
Serum Separation
What is serum ?
Serum : _______ - ______
Plasma : ____-____
Blood- cells and clotting factors; blood – cells
Serum separation:
Use _____ tube (_______ ), Leave blood for ______ at room temp. Then _______ before you Centrifuge at ____ for _____.
plain; no anticoagulant; 1 hour ; room; Separate the clot; 3000rpm; 10 min
Agglutination
Passive Agglutination
• The agglutination of _____________ that have been ________ or ______ to cells or insoluble particles (e.g., _____,_____)
soluble antigens or antibodies ; adsorbed or chemically coupled ; latex beads, charcoal
Reactions of passive agglutination can be up to ___ times more sensitive than _________ tests
five; direct agglutination
ELISA can test for specific organisms either by ____________ during an infection or _________.
detecting bacterial antigen; antibacterial antibody
ELISA
The detection of the antibody confirms __________ but it is not necessarily the ________
contact with an organism at some time; reason for a current infection.
ELISA is (Specific or non-specific?) , (sensitive or non sensitive?) , (simple or complex?) , (expensible or inexpensible?) & (reproducible or irreproducible?)
Specific; sensitive; simple; inexpensible and reproducible
ELISA is Used extensively to detect either ____ or ___ .
Ag or Ab
ELISA can not detect small quantities of Ag
T/F
F
It also detects small quantities of Ag
