Transcript TB Infection Control

Infection Control
For Tuberculosis
Dr. Amany Ibrahim
Specialist of Infection
Control Abbassia Chest
Hospital
Tuberculosis Transmission and
Pathogenesis
Etiology
M. tuberculosis
M. bovis
M. africanum
M. microti
M. canettii
M. caprae
M. pinnipedii
3
Characteristics of M. tuberculosis
• Slightly curved, rod
shaped bacilli
• 0.2 - 0.5 microns in
diameter; 2 - 4 microns
in length
• Acid fast - resists
decolorization with
acid/alcohol
• Multiplies slowly (every
18 - 24 hrs)
• Thick lipid cell wall
• Can remain dormant for
decades
• Aerobic
• Non-motile
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Transmission
of TB
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How is TB Transmitted?
• Person-to-person
through the air by a
person with TB disease
of the lungs
Source: CDC, 2000
 Less frequently transmitted by:
• Ingestion of Mycobacterium bovis found in unpasteurized milk
products
• Laboratory accident
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Fate of M. tb Aerosols
• Large droplets settle
to the ground
quickly
• Smaller droplets
form “droplet
nuclei” of 1–5 µ in
diameter
• Droplet nuclei can
remain airborne
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Transmission of M. tuberculosis
• Transmission affected by:
– Infectiousness of patient
– Environmental conditions
– Duration of exposure
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Characteristics of a Patient with TB
Disease
That Increase the Risk for Infectiousness
presence of cough;
• cavitations on chest radiograph;
• positive acid-fast bacilli (AFB) sputum smear result;
• respiratory tract disease with involvement of the larynx
• respiratory tract disease with involvement of the lung or
pleura (exclusively pleural involvement is less infectious)
• failure to cover the mouth and nose when coughing;
• incorrect, lack of, or short duration of antituberculosis treatment
• undergoing cough-inducing or aerosol-generating procedures

Persons at High Risk for Progression From LTBI
to TB Disease
• persons infected with HIV;
• persons infected with M. tuberculosis within
the previous 2 years
• infants and children aged <4 years;
• persons with a history of untreated or
inadequately treated TB disease ( chest
radiograph findings)
Persons at High Risk for Progression From
LTBI to TB Disease (con)
• persons with any of the following clinical conditions or
—silicosis,
—diabetes mellitus,
—chronic renal failure, end-stage renal disease (ESRD)
—certain hematologic disorders (leukemias and lymphomas),
—other specific malignancies (e.g., carcinoma of the head,
neck, or lung),
—body weight >10% below ideal body weight,
—prolonged corticosteroid use,
—organ transplant,
Vaccination with BCG probably does not affect
the risk for infection after exposure, but it
might:
1- decrease the risk for progression from
infection withM. tuberculosis to TB disease,
2- preventing the development of miliary and
meningeal disease in infants and young
children
Environmental Factors Increase the Risk
of Transmission of M. tuberculosis
• Exposure to TB in small, enclosed spaces.
• Inadequate local or general ventilation that
results in
insufficient dilution or removal of infectious
droplet nuclei.
• Recirculation of air with droplet nuclei.
• Inadequate cleaning and disinfection of
medical equipment.
• Improper handling of specimens.
TB Transmission and Pathogenesis
No infection (70%)
Adequate
Exposure
Non-specific
immunity
Inadequate
Infection (30%)
 Not everyone who is exposed to TB will become
infected
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Fundamentals of TB Infection Control
One of the most critical risk for health-care–
associated transmission of M. tuberculosis in
health-care settings is from patients with
unrecognized TB disease who are not promptly
handled with appropriate airborne
precautions or who are moved from an AII
room too soon as patients with unrecognized
TB and MDR TB)
All health-care settings need a TB infectioncontrol program designed to ensure prompt
detection, airborne precautions, and
treatment of persons who have suspected or
confirmed TB disease.
Such a program is based on a three-level of
controls, including administrative,
environmental, and respiratory protection
Administrative Controls
- Assigning responsibility for TB infection control
- Conducting a TB risk assessment of the setting.
- Developing and instituting a written TB infectioncontrol plan.
-Ensuring the timely availability of recommended
laboratory processing.
-Implementing effective work practices for the
management of patients with suspected
or confirmed TB disease.
-Ensuring proper cleaning, sterilization or
•
disinfection
-Focus on prevention, transmission, and
symptoms;
-Training and educating HCWs regarding TB,
with screening and evaluating HCWs who are
at risk for T.B .i.e., T.B screening program
- Using appropriate signage advising respiratory
cough etiquette; -
HCWs with TB disease should be allowed to return to work
when they :
1) have had three negative AFB sputum smear
results collected 8–24 hours apart, with at least one being an
early morning specimen
because respiratory secretions pool overnight;
2) have responded to antituberculosis treatment that will
probably be effective based on
susceptibility results.
3) In addition, HCWs with TB disease should be allowed to
return to work when a physician experienced in managing TB
disease determines that HCWs are noninfectious .
Environmental Controls
- Primary environmental controls consist of controlling the
source of infection by using local exhaust ventilation (e.g.,
hoods, tents) and diluting and removing contaminated
air by using general ventilation
- Secondary environmental controls consist of controlling the
airflow to prevent contamination of air in areas adjacent to
the source (AII rooms) and cleaning the air by using high
efficiency particulate air (HEPA), filtration, or UVGI.
Respiratory-Protection Controls
-Implementing a respiratory-protection
program,
- Training HCWs on respiratory protection, and
-Training patients on respiratory hygiene and
cough etiquette procedures.
What is infection control
Prevention of transmission
Visitor to
Worker to
Patient
Worker
Visitor
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Patient to
• Illness caused by TB can be prevented by
interrupting the transmission of the organism
from the reservoir to susceptible host.
• This can be achieved by following infection
control standard precautions :
1.
2.
3.
4.
Hand hygiene
Personal protective equipment PPE
Environmental controls
Isolation
1-Hand hygiene
Studies have shown that an average of only 40% of
HCWs adheres to hand hygiene practices in their
institutions.
 Plain (non-antimicrobial) soap.
 Antimicrobial soap (chlorhexidine)
 Alcohols 60-95%
 Chlorhexidine 2-4%
 Iodophors
 Phenol derivatives
 Quaternary ammonium compounds (QUATs)
Group
Alcohols
Chlorhexidine
2-4%
Gram
Pos.
+++
+++
Gram
Neg.
+++
++
M.TB
+++
+
Fungi
+++
+
Virus
+++
+++
Speed of
action
fast
60-95%
Persistent
activity
intermediate
Persistent
activity
Rare allergic
Rx.
Iodophors
+++
Phenol
derivative
Quaternary
Ammonium
compounds
+++
+
+++
+
++
+
+
-
++
+
-
++
+
+
comments
intermediate
intermediate
slow
Less irritating
than iodine
Activity
neutralized
by nonionic
surfactant
Used only in
combinations
with alcohol
WHO Recommended Guidelines for
Hand Washing and Hand Antisepsis
Wash hands with soap and water in the following
situations:
•
•
•
•
•
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Before starting the work
Before entering the ward
Before eating
After using the rest room
When visibly dirty or contaminated with
proteinaceous material, or visibly soiled with blood or
other body fluids,
if exposed to potential spore-forming organisms is
strongly suspected or proven .
If hands are not visibly soiled, use an alcohol based hand rub
for routine hand antisepsis in the following situations
(The 5 moments for hand hygiene)
•
•
•
•
•
Before patient contact
After patient contact
Before an antiseptic task
After body fluid exposure risk
After contact with patient surroundings
N.B. : When alcohol-based hand rub is already used, do not
use antimicrobial soap concomitantly.
P.P.E.
Masks
• Surgical masks reduce the spread of
microorganisms from the wearer (patient) it is
not used by the staff
• Patient with airborne infections use it to provide
protection against spread of infection large
particle droplets that are transmitted by close
contact and generally travel only short distances
(up to 3 feet) from infected patients who are
coughing or sneezing
Personnel Protective Equipment: Masks
• Surgical masks reduce
the spread of
microorganisms from
the wearer (protection
from exhaled droplets).
• They do not provide
protection to the
wearer from inhaling
small infectious
aerosols.
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• So for staff protection when caring for
patients with airborne infections as TB
particulate respirators or air purifying
respirators are recommended. They protect
only against particles not gases or vapors.
(Bacteria and viruses are particles)
• Particulate respirators include:
N95, N99 or N100 or
Filtering face piece respirators eg:FFP2,FFP3
How often do disposable respirators
need to be replaced?
• If a sufficient supply of respirators is not
available, healthcare facilities may consider
reuse as long as the device has not been
obviously soiled or damaged . Reuse may
increase the potential for contamination;
however, this risk must be balanced against
the need to fully provide respiratory
protection for healthcare personnel.
Consider wearing a loose-fitting barrier that does
not interfere with fit or seal (e.g surgical mask,
face shield) over the respirator
• Remove the barrier upon leaving the patient’s
room and perform hand hygiene. Surgical masks
should be discarded; face shields should be
cleaned and disinfected.
• Remove the respirator and either hang it in a
designated area or place it in a paper bag.
(consider labeling respirators with a user’s name
before use to prevent reuse by another
individual.)
• Use care when placing a used respirator on
the face to ensure proper fit for respiratory
protection and to avoid contact wit infectious
material that may be present on the outside
of the mask.
• Perform hand hygiene after replacing the
respirator on the face.
Personnel Protective Equipment:
Respirators
N95 respirators effectively filter out > 95%
(98% for FFP3) of the particles ≥ 03 μm
N95/ FFP2
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FFP3
Why fit testing?
• Ensure that each person received an adequate
fit while wearing a respirator
• Determine appropriate make/model
• Determine appropriate size
• Ensure proper seal between respirator and
wearer
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Fit testing
• Employees should pass an appropriate qualitative fit
test or quantitative fit test:
– prior to initial use
– whenever a different respirator facepiece (size, type,
model or make) is used, and
– periodically thereafter
• Additional fit test whenever changes in physical
condition or job description that could affect
respirator fit are noticed or reported
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Physical factors contributing to poor
fitting respirators
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•
•
•
•
•
•
•
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Weight loss/ gain
Facial scarring
Changes in dental configuration (dentures)
Facial hair
Cosmetic surgery
Excessive makeup
Mood of workers (smiling/ frowning)
Body movements
Sources of facepiece leakage
• Through air-purifying element
• Through exhalation valve
• Around facepiece/skin interface
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Find centre of nose piece and bend
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Open respirator
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Place straps on back of hand
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Place respirator on face
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Pull top strap over head
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Place top strap on crown of head
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Pull lower strap over head
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Place strap at base of head
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Pinch metal clip around nose
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Pull respirator over chin
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Check for major leaks
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1. Normal breathing
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2. Deep breathing
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3. Move head side-to-side
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4. Move head up-and-down
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5. Talk non-stop
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6. Jogging or walking in place
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7. Normal breathing
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Smile… you passed
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Environmental Control
Ventilation is: air movement pushing and / or pulling
particles & vapors in a controlled manner.
• is critical, used for spread control of airborne
human resource infectious agents e.g. TB, Varicella
Zoster, and Rubella
Maybe:
• Natural ventilation
• Mechanical ventilation
• Mixed ventilation
Natural ventilation
Depends on:
• Building location, dimension, window types,
operation, design and size
• Other openings, doors………..
• External elements (walls, screens)
• Wind speed
• Other rooms location
• Air changes per hour = ACH moving the total amount
of air out of a room and replace by fresh air
(recommended 12 – 18 )
Natural ventilation(cont.)
• Advantages:
- High ventilation rate
- Low cost (installation & maintenance)
- Applicable
• Disadvantages:
- Climate dependant
- Noise pollution
- No privacy
- Security
- No direction control of contaminated air but
dilution
Mechanical ventilation
• Created by fans usage to force air exchange & to
drive air flow
• Works by generating negative pressure to drive air
inwards, all doors & windows kept closed, minimum
12 ACH is maintained
Negative pressure rooms:
- doors and windows closed
- pressure difference 10%, higher to lower, into the
room
- Evaluation: by smoke test, velocity meter,
pressure sensor
Mixed Mode Ventilation
• Combines mechanical & natural ventilation
• Through exhaust fan to increase ACH
• Useful in places where natural ventilation is not
suitable e.g. very cold climate & when full
mechanical ventilated airborne precaution rooms
are not available.
UVGI
UVGI is a form of electromagnetic
radiation with wavelengths
between the blue region of the visible
spectrum and the radiograph region.
UVGI has been recommended as a
.
supplement or adjunct to other TB
infection-control and ventilation measures
in settings in which
the need to kill or inactivate M. tuberculosis
is essential
Applications of
UVGI.
UVGI is considered a method of air cleaning
because it can kill or inactivate microorganisms
so that they are no longer able to replicate and
form colonies.
UVGI is not a substitute for HEPA filtration before
exhausting the air from AII rooms back into the
general circulation.
UVGI lamps can be placed in ducts, fixed or
portable room air-recirculation units, or upper-air
irradiation systems
.
Duct irradiation.
Duct irradiation is designed to kill or inactivate
M. tuberculosis without exposing persons to
UVGI.
In duct irradiation systems, UVGI lamps are
placed inside ducts to disinfect the exhaust air
from AII rooms or other areas in which M.
tuberculosis might be present before it is
recirculated by the system (less desirable)
Upper-air irradiation.
In upper-air irradiation, UVGI lamp fixtures
are suspended from the ceiling and installed
on walls. The base of the lamps are shielded
to direct the radiation upward and outward to
create an intense zone of UVGI in the upper
air while minimizing the levels of UVGI in the
lower part of the room where the occupants
are located. The system depends on air
mixing to move the air from the lower part of
the room to the upper part where microbialcontaminatedair can be irradiated
Upper-air UVGI can be used in various settings.
• AII rooms and rooms in which aerosol-generating or
aerosol- producing procedures (e.g., bronchoscopy,
sputum induction and administration of aerosolized
medications) are performed.
• Patient rooms, waiting rooms, corridors, central
areas, and other substantial areas in which patients with
undiagnosed TB disease could potentially contaminate
the air.
• Operating rooms and adjacent corridors where
procedures are performed on patients with TB disease.
.
Health and safety issues
. Short-term overexposure to UV radiation can caus
erythema , photokeratitis (inflammation of the corne
and
(i.e., inflammation of the conjunctiva) Symptoms
of photokeratitis and conjunctivitis include a feeling
sand in the eyes, tearing, and sensitivity to light.
Photokeratitis and conjunctivitis are reversible
conditions, but they can debilitating while they run t
course. the health effects of UVGI are usually not
evident until after exposure has ended (typically 6–
-12 hours later) .
)
Upper room UVGI
UVGI cleaning
UVGI cleaning
Routine Maintenance
• Clean with alcohol once a month.
• Changed every 10 months.
• One lamp is efficient for every 12-24 m2
Conclusions
• Recommended as one approach to control
spread of infectious diseases, TB in particular
• Efficacy is maximised if implemented properly
and with adequate ventilation in place.
HEPA FILTER
High-efficiency particulate air filter
• Efficient as p-100 filters , it provides a higher level
of protection in health care facilities especially in
isolation rooms.
• Their reusable elements should be cleaned an
disinfected after use and the filters replaced in
accordance with manufactures recommendations
• All used filters should be considered potentially
contaminated with infectious material and must
be safely discarded.
HEPA filtration can be used to supplement other
recommended
ventilation measures by providing a minimum
removal efficiency of 99.97% of particles equal
0.3 μm in diameter. This air-cleaning method is
considered an adjuvent to other ventilation
measures. Used alone, this method neither
provides outside air for occupant comfort nor
satisfies other recommended ventilation
measures .
Portable room-air recirculation systems.
Portable room air recirculation units with HEPA
filters (also called portable air cleaners) can be
considered when
1) a room has no general ventilation system
, 2) the system cannot provide adequate ACH
, or 3) increased effectiveness in airflow is
needed.
Effectiveness depends on the ability of the
portable room-air recirculationunit to circulate as
much of the air in the room as
possible through the HEPA filter.
.
Portable HEPA filtration units should be designed
to 1) achieve >12 equivalent ACH
, 2) ensure adequate air mixing in all areas of the
rooms , and 3) be compatible with the ventilation
system.
An estimate of the ability of the unit to circulate
the air in a room can be made by visualizing airflow
patterns (estimating room air mixing]). If the air
movement is adequate in all areas of the room
, the unit should be effective
.
One or more lower-efficiency disposable prefilters installed upstream can extend the life of a
HEPA filter by at least 25%.
Pre-filters should be handled and disposed
of in the same manner as the HEPA filter. persons
performing maintenance and replacing filters on
any ventilation system that is probably
contaminated with M. tuberculosis should wear a
respirator in addition to eye protection and
gloves.
Isolation
• Infectious patients (MDR-TB) meet their visitors in
open air
• Separation of infectious patients from non infectious
ones
• Optimal number of isolation rooms per facility ranges
fr0m 1/30 beds in general hospitals to 1/5 beds in
acute care hospitals
• Patients’ screening in waiting areas to identify
potentially infectious patients and prevent HCW
exposure
Isolation (cont.)
• Place TB suspects in separate, well ventilated
waiting areas, use surgical masks & minimize
waiting time
• Use of surgical masks during movement from
one place to another
• Separation of TB cases in separate building
with separate access
• Physical means of separation (partitions)
Isolation (cont.)
• Plastic sheets covering mattresses, beds
• Rooms good ventilated, with toilets supplied
with soap and paper drying towels
• Decrease the number of health staff & visitors
authorized to enter following IC precautions
• Screen staff periodically (X-ray / Sputum)
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