1
Q
Def of Infectious Diseases
A
- Clinically evident diseases resulted from the presence of pathogenic microorganisms with the potential of transmission from a person to another.]
- Infectious Diseases are many but limited by our knowledge, facilities, & ignorance.
2
Q
what are causes of Infectious Diseases?
A
- Bacterial.
- Viral.
- Fungal.
- Parasitic.
2
Q
Samples will be subjected to:
A
- Phenotypic microbiological analyses.
- Immunological-serological analyses.
- Genotypic-Molecular biological analyses.
3
Q
Types of samples
A
- Blood.
- Sputum.
- Urine.
- CSF.
- Stool.
- Pus.
4
Q
Phases of diagnosis
A
4
Q
Preanalytical phase of diagnosis
A
5
Q
Importance of Sampling
A
(good sample = true result)
- The successful identification of microbe depends on sampling.
- The specimen is the beginning:
As all diagnostic information from the laboratory depends upon the knowledge by which specimens are chosen & the care with which they are collected & transported.
5
Q
Proper selection of type of sample
A
Collect the appropriate type of specimen for diagnosis of the infectious disease.
5
Q
what does the quality of the sample Depend on?
A
- Proper Selection
- Proper Collection
- Proper Transport
6
Q
Proper collection of sample
A
Avoid harming the patient & causing discomfort
Site:
- Collected tom: site pathingen is most likely to be round.
Time:
- The acute stage is the best.
- Before antimicrobial therapy has begun.
Quanlity:
- Sufficient quantity.
6
Q
proper transport of sample
A
- Specimens should be protected from heat & cold.
- Specimen transported promptly Within 2 hours.
- Use of transport media especially for anaerobic culture.
7
Q
Def of Direct methods of diagnosis
A
- Detection of organisms, their structural components & their products.
7
Q
Clinical specimens from various organs
A
- Circulatory System.
- (Skin- Abscess - Wound) Specimens.
- Eyes & Ears.
- Respiratory System.
- Central Nervous System.
- Urinary Tract.
- Genital Tract.
- Oral Cavity.
- Gastrointestinal Tract.
- Body Fluids.
8
Q
Examples of Direct methods of diagnosis
A
- Macroscopic evaluation.
- Microscopy (Unstained & Stained).
- Culture & biochemical reactions.
- Detection of microbial antigens & products.
- Molecular identification of nucleic acids (PCR & DNA probe technology).
9
Q
Def of InDirect methods of diagnosis
A
- Detection of antibodies against the microorganism in the patient’s serum.
10
Q
Examples of InDirect methods of diagnosis
A
- Serologic method
10
Q
Macroscopic examination of samples
A
11
Q
Microscopic examination of samples
A
12
Q
Def of Culture
A
The process of growing & propagating organisms in a media that is conducive for their growth.
13
Q
Importance of Culture
A
It Reproduce the organism for use for additional testing
13
Q
Types of Culture
A
14
Q
Identification of bacteria
A
- Morphology.
- Growth requirements.
- Biochemistry.
- Enzymes.
- Antigens.
15
Q
Rapid identification of bacteria
A
Automated bacterial identification & Antimicrobial susceptibility systems.
16
Q
Example of Automated bacterial identification and antimicrobial susceptibility systems
A
VITEK system.
17
Principle of **Automated bacterial identification and antimicrobial susceptibility systems**
17
Time of results of **Automated bacterial identification and antimicrobial susceptibility systems**
Available within 6-8 hours.
18
Drawbacks of Culture of Pathogenic Microbes
18
Diagnosis of infection with slow-growing or non-culturable bacteria tends to rely on....
**Direct:** by molecular methods (PCR).
**Indirect:** by serodiagnosis (antibody detection).
19
Diagnostic Methods through time
20
Def of **Direct Antigen detection**
- Assays are available for rapid detection of
- Bacterial Antigens (surface antigen - soluble antigen).
- Or toxin in biological fluids e.g. (CSF - blood - urine).
20
When are **Direct Antigen detection** useful?
- Prior antibiotic therapy has been initiated & cultures are negative after 24 hours of incubation.
- Rapid results in critical ill patients e.g. meningitis.
21
Principle & Types of **Direct Antigen detection**
21
Def of **Molecular biology Techniques**
Molecular detection techniques for bacterial, viral and fungal DNA.
22
Importance of **Molecular biology Techniques**
23
Disadvantages of **Molecular biology Techniques**
24
Def of **MULTIPLEX PCR**
Simultaneous detection of dozens of targets from one patient sample
25
Characters of **MULTIPLEX PCR**
26
Def of **Indirect tests (serodiagnosis & Immune status tests)**
Tests for detection of specific antibody for infectious agents including (IgM - IgG - IgA).
27
What is diagnostic in **Indirect tests (serodiagnosis & Immune status tests)**?
Rising antibody titer (at least 4 folds) is diagnostic.
28
Time of sample collection in **Indirect tests (serodiagnosis & Immune status tests)**
Samples are withdrawn at acute & convalescent stages (within 14 days).
29
Techniques of **Indirect tests (serodiagnosis & Immune status tests)**
29
Advantages of **Indirect tests (serodiagnosis & Immune status tests)**
- Inexpensive.
- Easy to perform.
- Allows identification of:
* Acute infection → IgM.
* Past infection → IgG.
30
Disadvantages of **Indirect tests (serodiagnosis & Immune status tests)**
- Delayed response.
- False negative results during sero-conversion window.
- Time of infection not always clear.
31
Sampling for mycological examination
- Clean the site with alcohol 70%.
- Sterile scalpel is used for scrapping.
- Sterile scissor is used for trimming the nails.
- Scales are transferred in clean dark paper.
32
Inoculation of fungal infections
33
Sampling for viral examination
**Time:** Sample should be collected during the most active stage of the disease.
**Transport:**
* Samples as (urine - stool - sputum - CSF) are transported directly to the lab.
* Swaps from (throat - nose - vesicles - cervix) are transported in viral transport medium.
34
Biohazard label should be used for containers of .....
(HBV - HCV - HIV)
35
Methods of viral detection
36
Def of **MIC (minimum inhibitory concentration**
The lowest concentration of antimicrobials that will inhibit the growth of organisms.
36
importance of **MIC (minimum inhibitory concentration**
Confirm resistance of organisms to an antimicrobial agent.
37
Methods of **MIC (minimum inhibitory concentration**
38
Post-Analytical phase of diagnosis
- Reporting of:
* Identification.
* Antibiotic sensitivity.
- Treatment
39
Def of **Rapid Detection Tests**
Tests that give results in minutes to 1-2 hours.
40
Characters of **Rapid Detection Tests**
- Accurate.
- Simple to use.
- Low cost.
- Stable under extreme conditions.
- Little or no processing.
- Culturally acceptable "Give the same result of the culture".
- Easy to interpret.
41
Revolution in Direct Detection of Infections
- Direct antigens.
- Direct antibody.
- Nucleic Acid (NA) based technology.
42
Check conclusion
..
43
Check take home messages
..
Drafts
flashcards
Decks in class (11)
# Cards
