Laboratory Diagnosis of Bacterial Infections Flashcards by Iseoluwa Ojo

The diagnosis of a microbial infection begins with an assessment of ________ and _______ features, leading to the formulation of a diagnostic hypothesis.

clinical and epidemiologic

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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)

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Site of sampling

Blood

Sterile or non sterile

Sterile

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Site of sampling

Cerebrospinal fluid (CSF)

Sterile or non sterile

Sterile

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Site of sampling

Sterile

Body fluids (______ and ______ )

Peritoneal and pleural

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Site of sampling

Non-sterile (________)
_____tract
Ear, eye and mouth
____(wound and abscess)
______(mid-stream)
Feces

normal flora

Respiratory

Skin; Urine

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Microscopy

Could be :
• Unstained preparations
• “________ “
Or

•____________ eg for _____

Wet prep

Dark-ground illumination ; syphillis

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By Microscopy

Could be :
•_______ preparations

• _______ preparations

Unstained

Stained

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Microscopy
Could be :

• Stained preparations

•______ -stain
•______ stain
• ________

Gram

Acid-fast

Fluorescence

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Fluorescence (stained microscopy preparation)
Could be :

•______, e.g. _______
Or
•_______

Direct; auramine

Immunofluorescence

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Types of stains

_______ stains

________ stains

Simple

Differential

Structural

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Types of stains

Simple stains
-how many dyes are used??
-reveals _____,______, and _____

one dye Is used

shape, size, and arrangement

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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

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Types of stain

Structural stains
-to __________________________
-eg _______ and _____ stains

reveal certain cell parts
not revealed by conventional methods

capsule and flagellar

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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

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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

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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

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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.

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The Gram stain also identifies the bacterium’s _____ and ____

shape and behaviour.

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Cocci are ____ in shape Bacilli are _____-shaped
Some bacteria form clusters whilst others form chains

round

rod

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Fluorescence Microscope

Is Modified microscope with ____ source and filter.

Uses dyes that ______ when bombarded with ______ rays- fluorescence

Used in diagnosing infections

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An ultraviolet radiation

emit visible light

shorter UV

Culture of pathogenic microbe

Solid media
•________

•_______

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Agar plates

Slopes

Culture of pathogenic microbe

Solid media

• Agar plates
For ________
For ________

• Slopes
For _______culture, e.g. _____________ media for TB

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Identification; Enumeration

safe long-term ; Lowenstein-Jensen

Culture of pathogenic microbe

• Liquid media ( ____ )
• For _______ or ________
• E.g. _____ cultures

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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

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

Laboratory Diagnosis of Bacterial Infections Flashcards

(50 cards)