430 likes | 1.06k Views
Pathogenesis of Tuberculosis. Globally, millions of people have tuberculosis (TB)Transmission by aerosolsAgent - Mycobacterium tuberculosis (M.tb)Infection vs. disease Infection may be latent or progress to diseasePrimarily affects lungs but may infect other organs. M.tuberculosis. - acid-fast rod shaped bacterium - resist decolorization w acid alcohol- mycolic acid and waxes in cell wall- does not release stain primary stain.
E N D
1. TB Laboratory Safety: Practices and Principles-An International Perspective
2. Pathogenesis of Tuberculosis Globally, millions of people have tuberculosis (TB)
Transmission by aerosols
Agent - Mycobacterium tuberculosis (M.tb)
Infection vs. disease
Infection may be latent or progress to disease
Primarily affects lungs but may infect other organs
3. M.tuberculosis
- acid-fast rod shaped bacterium
- resist decolorization w acid alcohol
- mycolic acid and waxes in cell wall
- does not release stain primary stain
5. Pathogensis
- ability of organism to cause disease
- route of transmission
- stability of organism
- infectious dose
- concentration of organisms per volume
- origin of agent
- condition of host
6. Mycobacterium tuberculosis
…is spread through the air from person to person via
coughing, sneezing, and even singing and speaking.
Tiny invisible droplets dry quickly to form droplet nuclei that
are less than 5 microns in diameter. They can contain disease
organisms such as tubercle bacilli. These droplets may remain
suspended in the atmosphere for several hours. Another
person can breathe in the particles and become infected.
This is especially dangerous in a confined area. Keep in mind,
when appropriate techniques are employed, there is very little
risk of acquiring infection in the laboratory.
Administrative controls should limit exposure.
It is vital that all personnel be aware of potential hazards and
work in a careful manner. Mycobacterium tuberculosis
…is spread through the air from person to person via
coughing, sneezing, and even singing and speaking.
Tiny invisible droplets dry quickly to form droplet nuclei that
are less than 5 microns in diameter. They can contain disease
organisms such as tubercle bacilli. These droplets may remain
suspended in the atmosphere for several hours. Another
person can breathe in the particles and become infected.
This is especially dangerous in a confined area. Keep in mind,
when appropriate techniques are employed, there is very little
risk of acquiring infection in the laboratory.
Administrative controls should limit exposure.
It is vital that all personnel be aware of potential hazards and
work in a careful manner.
10. Direct Smear Microscopy -primary method for diagnosis of TB
-perform without personal respiratory
protection
-No documented transmission on open
bench
-increased risks when HCWs have contact with coughing patients
-administrative controls should limit this
exposure
11. Specimen Collection
Two kinds of containers are recommended for
sputum collection:Specimen Collection
Two kinds of containers are recommended for
sputum collection:
12. The first is a disposable wide-mouthed, screw-capped
container. It is made of unbreakable transparent plastic. It
must be hermetically sealed to keep the specimen from leaking
and drying out.
The second is a screw capped “Universal container”
made of heavy glass which can be first sterilized, cleaned
and used again.
Many countries use their own containers.
The first is a disposable wide-mouthed, screw-capped
container. It is made of unbreakable transparent plastic. It
must be hermetically sealed to keep the specimen from leaking
and drying out.
The second is a screw capped “Universal container”
made of heavy glass which can be first sterilized, cleaned
and used again.
Many countries use their own containers.
13. The greatest risk of infection in the laboratory involves sputum
collection. Preparing smears presents less risk to the lab
worker than exposure to direct coughing.
Since TB patients are sometimes directed to the lab for sputum collection, precautions must be taken to minimize the risk of exposure of laboratory staff and others.
Never collect sputum specimens inside the
clinic or laboratory.
The greatest risk of infection in the laboratory involves sputum
collection. Preparing smears presents less risk to the lab
worker than exposure to direct coughing.
Since TB patients are sometimes directed to the lab for sputum collection, precautions must be taken to minimize the risk of exposure of laboratory staff and others.
Never collect sputum specimens inside the
clinic or laboratory.
14. It is safer to collect the specimens outside.
At all times, avoid creating aerosols in the lab!
A daily routine that is followed exactly will help
maintain safe conditions.
Strict adherence to safety regulations in the laboratory is
crucial. Safe practices include:
· Washing hands frequently and always before and after
performing any procedures.
· Establishing airflow in working areas that will carry
infectious particles away from lab personnel. This air
should be exhausted into a remote location.
· Strictly refraining from smoking and eating in the lab!!!
· Wearing protective clothing and use of protective
equipment.
It is safer to collect the specimens outside.
At all times, avoid creating aerosols in the lab!
A daily routine that is followed exactly will help
maintain safe conditions.
Strict adherence to safety regulations in the laboratory is
crucial. Safe practices include:
· Washing hands frequently and always before and after
performing any procedures.
· Establishing airflow in working areas that will carry
infectious particles away from lab personnel. This air
should be exhausted into a remote location.
· Strictly refraining from smoking and eating in the lab!!!
· Wearing protective clothing and use of protective
equipment.
15. Laboratory Arrangement
To perform TB microscopy, a laboratory must have three areas:
Laboratory Arrangement
To perform TB microscopy, a laboratory must have three areas:
16. Laboratory Arrangement for AFB Smear Microscopy Plan the lay out of laboratory room for an ease and safe work area
Plan areas for each step and the movement of the sputum and work with AFB smears
Movement of people in the work area must be minimized
17. Laboratory Arrangement
18. Transport of Specimen
Specimens should be packed and transported according to
your country’s NTP guidelines.
Specimen Handling
Open the transport box carefully and examine it for cracked
or broken containers. Discard any broken or leaking container
and request another specimen.
All specimens must correspond with the accompanying list
containing data of the TB suspect.
Once verified, record all information in the laboratory
register.Transport of Specimen
Specimens should be packed and transported according to
your country’s NTP guidelines.
Specimen Handling
Open the transport box carefully and examine it for cracked
or broken containers. Discard any broken or leaking container
and request another specimen.
All specimens must correspond with the accompanying list
containing data of the TB suspect.
Once verified, record all information in the laboratory
register.
19. Smear Preparation
To ensure a safe and consistent workflow, always arrange
equipment and materials in the same way at the workbench.Smear Preparation
To ensure a safe and consistent workflow, always arrange
equipment and materials in the same way at the workbench.
20. Surgical masks DO NOT protect against TB infection !
Effective respiratory protection, such as an N95 respirator, is
expensive, and probably unnecessary if the technician uses
appropriate technique.
Careful handling during smear preparation should produce
minimal aerosols.
The low risk of infections during these procedures may not
justify the cost of respirators and gloves where there may be
limited resources for TB control.
Each country must evaluate the risks and decide on the level
of protection that is appropriate with the resources that may
be available.
In this training video, the technicians do not wear gloves or
masks. Hand-washing and careful technique are acceptable
practices for most countries.
Remember, safety is everyone’s concern
no matter what job is being performed.Surgical masks DO NOT protect against TB infection !
Effective respiratory protection, such as an N95 respirator, is
expensive, and probably unnecessary if the technician uses
appropriate technique.
Careful handling during smear preparation should produce
minimal aerosols.
The low risk of infections during these procedures may not
justify the cost of respirators and gloves where there may be
limited resources for TB control.
Each country must evaluate the risks and decide on the level
of protection that is appropriate with the resources that may
be available.
In this training video, the technicians do not wear gloves or
masks. Hand-washing and careful technique are acceptable
practices for most countries.
Remember, safety is everyone’s concern
no matter what job is being performed.
21. Washing Hands
Always wash hands with soap and water after
handling specimens and containers.Washing Hands
Always wash hands with soap and water after
handling specimens and containers.
22. SAFE DISPOSAL OF WASTE MATERIALS Infectious waste can be divided in two types
Disposable and re-usable materials
Infectious TB lab waste is a risk to health care workers and the community
Waste must be sterilized or disinfected before it leaves the laboratory
Discard contaminated materials and sputum containers in 5% Phenol disinfectant
23. Disposable of Materials Incinerate: Use temperature not less than 100 0 degrees and dump in a hole or autoclave (if autoclaves is available)
Dump hole: Place waste in hole (about 1 m) and burn
Cover hole with wood or a plate when half filled to prevent access by people, animals and birds
24. Re-usable Materials Place slide holders, forceps in a container with disinfectant
Boil 20 min or more-or autoclave and wash for re-use
25. FLOW CHAR FOR DISPOSAL OF SPUTUM CONTAINERS
26. FLOW CHART FOR DISPOSAL OF INFECTIOUS WASTE FROM TB LABORATORY
27. IMPORTANT POINTS TO REMEMBER: Autoclaving is the safest and most satisfactory method of sterilization
If autoclave is not available incinerate or burn the infectious waste
Disinfect TB work surface areas with cotton wool soaked in 5% Phenol.
28. Risk Assessment
29. Risk Assessment Background information and ability to visualize potential outcomes
Review laboratory records:
-equipment maintenance
-employee training
-environmental monitoring
-injury and surveillance reports
Inspect the laboratory:
-periodic walk-throughs
-formal inspections by certifying agencies
30. Regular intervals, at least annually, more frequently if problems are discovered
When a change occurs in the lab:
-relocation or renovation
-new employee(s)
-new infectious agent or new reagent
-new test or equipment Review published material, equipment manuals, manufacturers bulletins and newsletters, product inserts, scientific journals, published safety manuals and guidelinesReview published material, equipment manuals, manufacturers bulletins and newsletters, product inserts, scientific journals, published safety manuals and guidelines
31. Biosafety Cabinets (BSC) BSC - Class I
-draws air into the cabinet and exhausts
-protects environment from aerosols
-produces negative pressure in the room
-type of cabinet needed in most laboratories
BSC - Class II
-laminar flow and exhausts air
-protects specimen and HCW
-poor practices/maintenance increase hazard
Monitor air flow daily for both types of cabinets
32. Biosafety Cabinets (BSC) Provide protection when used with appropriate lab
practices
Improper use and poor maintenance can be
hazardous to the HCW and others in the work area
-Bunsen burners disrupt air flow patterns
-Contaminated hands/gloves endanger all lab staff
Require daily monitoring and annual certification
34. Cultures, drug susceptibility and other tests
-use biological safetycabinets to perform these procedures
- BSC should be certified annually
- Technologists should be well trained in use, care and maintanence of BSC Safety with Suspensions of M.tb
37. flaming wet smears, centrifugation
vortexing, pipetting, blending or sonicating specimensflaming wet smears, centrifugation
vortexing, pipetting, blending or sonicating specimens
38. Safe TB Laboratory Practices Routine performance of risk assessments
Control ventilation and airflow patterns
Prevent leaking specimen containers and contaminated work forms
Frequent and appropriate hand washing
39. Safe Practices cont’d Prevent aerosols and spills
Use of disinfectants and proper waste disposal
No eating, drinking or smoking, use of cell phones in the lab
Have an emergency plan and supplies available
40. References 2000. TB Microscopy in Pacific Island countries Japan International Cooperation Agency and The research Institute of Tuberculosis
Date of Publication. Acid-fast Direct Smear Microscopy,WHO, IUATLD, CDC, KNCV, JATA, APHL
Draft publication. External Quality Assessment for AFB Microscopy
1995. Mycobacterium tuberculosis: assessing your laboratory. ASTPHL and CDC.
2002. Zambia AFB microscopy Training Manual. Central Board of Health.
1993, Channel BTE CO, Inc. About Tuberculosis, Booklet #37788. Southfield, MA.
1998. Laboratory Risk Assessment: What, Why and How. Centers for Disease Control and Prevention
WHO. 1999. Guidelines for Prevention of Tuberculosis in Healthcare facilities in resource–limited settings