Tuberculosis And Airborne
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Transcript of Tuberculosis And Airborne
Tuberculosis Among Thai
Healthcare Workers:
a Human or System Failure
Anucha Apisarnthanarak, M.D.
Assistant Prof.
Thammasat University Hospital
Adjunct Visiting Prof.Washington University School of Medicine, USA
Objectives
Case presentation
Is this a human error?
Is this a system error?
How to develop intervention to reduce TB transmission in resource limited setting
An ICN notified you that one OR
nurse had been admitted for active tuberculosis
She had SLE and on
prednisone for the past 3
months. She had been
contacting to her roommate
and others OR nurses. Her
symptoms of coughing persisted for the past 3 weeks.
What will you do next?
A) Leave it alone
B) Contact tracing and give INH for all contacts
C) Contact tracing and give INH for those who
had positive PPD
D) Contact tracing, double steps PPD, repeat in
the next 3 months, and gave INH for those who
had evidence of recent converter
E) I am not sure what to do
Transmission
Arguing for not doing PPD
skin test
Difficult to educate physicians to perform
CXR prior to INH prescription
Lack of specificity
INH resistant incidence is high (12-15%)
Benefit may wane after 5 years
Etc.
What we did?
Postexposure Detection of Mycobacterium
tuberculosis Infection in Health Care Workers in Resource-Limited Settings
Apisarnthanarak A, et al. Post-exposure detection of TB in Thai HCWs. CID, 2008
No. (%) of patients
Second TST With
M.turberculosi
s infection at 2-
year follow-up
(n = 6)
Initial TST reaction size
Initial TST
(n = 95)
No change
(n = 87)
Increase of
>10 mm
(n = 8)
> 15 mm 20 (21) 18 (21) 2 (25) 2 (33)
10-15 mm 65 (68) 63 (72) 2 (25) 1 (17)
No reaction 10 (10) 6 (7) 4 (50) 3 (50)
Influence of Bacille Calmette-Guerin Vaccination on Size of Turculin Skin Test Reaction: To What Size?
Tissot, et al. Service of Infectious Diseases, University Hospital,Lausanne, Switzerland. Clin Infect Dis, 2004
Khawcharoenporn T, Apisarnthanarak A, et al. TST among MS with prior BCG. ICHE, 2008 (in press)
Among Thai HCWs and in
other resource-limited settings
Among HCWs around the world
Khawcharoenporn T, Apisarnthanarak A, et al. TST among MS with prior BCG. ICHE, 2008 (in press)
Study
location year
TB case
rate per 100,000
Definition of BCGV
BCGV rate
TST
reactions
10 mm.
BCGV effect
Effect on 1st step TST positivity
Booster effect on 2nd step TST
Brazil, 2001 62 BCGV scars 70% 57% Yes, at cut-off level 10 mm. Yes, for 6 mm. increase
Chile, 1990 ND BCGV scars 84% 48% Yes, at cut-off level 10 mm. Yes, for 6 mm. increase
Israel, 1997 10 Recall 63% 60% No, at cut-off level 10 mm. Yes, for 6 mm. increase
Ivory Coast,
1997
172 BCGV scars
and recall
83% 79% No, at cut-off level 10 mm. ND
Malaysia,
2001
66 Recall 99% 78% No, at cut-off level 10
and 15 mm.
ND
Mexico,
1998
52 BCGV scars 84% 64% Yes, at cut-off level 10 mm. ND
Thailand,
1996
64 BCGV scars 77% 68% Yes, at cut-off level 10 mm.
No, at cut-off level 15 mm.
ND
Turkey,
2002
96 BCGV scars
and recall
93% 83% Yes, at cut-off level 10 mm. ND
Uganda,
2001
402 BCGV scars 41% 57% No, at cut-off level 10 mm. ND
Our study 85 BCGV scars 58% 62% Yes,at cut-off level10-19mm.
No, at cut-off level 20 mm.
Yes, for 6-9 mm. increase
No, for 10 mm. increase
Given the experience with
Avian Influenza, do HCWs in
your hospital comply with
isolation precaution and use of PPE for TB?
A) Yes
B) No
C) Maybe
Impact of Knowledge
and Positive Attitude
About H5N1 on Infection
Control Practices For
Airborne Diseases Among Thai HCWs
Apisarnthanarak A, et al.
Infect Control Hosp Epidemiol, 08
Do our HCWs lack of knowledge and awareness for TB?
Knowledge & Practices
98% of HCWs had good knowledge on
AI prevention.
Only 33% follow all appropriate IC
protocol for other airborne diseases.
Teaching Point
“Good knowledge doesn’t always translate
into good IC practices and
behaviors…additional interventions are
needed”
Is this a system error?
Alonso-Echanove, et al. TB among HCWs in Peru. CID, 2002
1994 199719961995
Year
Ra
te p
er
10
0,0
00
HC
Ws
500
2000
7000
1500
1000
0
709
488
187
60
1163
709
233
187
1418
581
466
334
181
6977
932
792
709
121
Laboratory
Medicine
ED/ICU
All hospital
Other areas
Evaluation of potential risk factors for Mycobacterium
tuberculosis infection among health care workers (HCWs) from clinical and laboratory areas
Variable
Clinical areas Laboratory areas
n/N PRR(95% Cl)
P n/N PRR(95% Cl)
P
Employment in medicine wards
92/121 2.1(1.5-2.9) <.001 _ _ _
Helped in sputum collection
57/71 1.5(1.2-1.9) <.001 1/1 _ NS
Contact with person with active tuberculosis
106/142 3.2(1.9-5.3) <.001 34/39 1.9(1.3-2.7) <.001
Duration of employment≥1 year
102/156 1.5(1.0-2.2) .01 37/52 1.2(0.8-1.8) NS
Use of common staff areas
106/171 1.1(0.8-1.7) NS 41/46 2.7(1.6-4.5) .001
Teaching Point
“TB is most likely to be transmitted
when health care workers and
patients come in contact with
patients who have unsuspected TB
disease, who are not receiving
adequate treatment, and who have
not been isolated from others.”
How to develop
intervention to reduce
TB transmission in
resource limited setting?
Hierarchy of Infection Controls
Work Practice and Administrative Controls are policies
and practices to reduce risk of exposure, infection, and
disease
Environmental Controls are equipment or practices to
reduce the concentration of infectious bacilli in air in
areas where contamination of air is likely
Respiratory Protection is used to protect personnel who
must work in environments with contaminated air
How to develop intervention to reduce TB transmission in resource limited setting?
Components of TB
Infection Control Plan
Screen clients to identify persons with symptoms of TB
disease or on treatment for current TB
Educate on TB in general and on cough hygiene; provide
face masks or tissues to symptomatic (suspect) or known
cases
Expedite TB suspect/case receipt of services
Investigate on site or refer TB diagnostic services and
treatment
Pathway for avian influenza is well established
Components of TB
Infection Control Plan (2)
Use and maintain environmental control measures
Train and motivate staff to recognize TB disease in
themselves
Train and educate staff on TB and the TB infection
control plan
Monitor and improve plan’s implementation
Don’t be bias: Thailand is
a model country for WHO
TB intervention campaign
Environmental Control
Measures
Goal: reduce droplet nuclei containing
M. tuberculosis in the air
Means: maximize controlled natural ventilation
Design of waiting areas, special exam rooms
for those with symptoms
Fans and fixed open windows and doors
Environmental Controls
Ventilation (natural and mechanical)
Filtration
Upper room UVGI (but expensive and less effective
when humidity >70%)
Optimal use of interior space (also an admin issue)
Perform sputum-induction procedures outside or in
special ventilated booths
Natural Ventilation
Door
Air Mixing and Directional Flow
Direction of Natural Ventilation or Incorrect Working Locations
Direction of Natural Ventilation or Correct Working Locations
However, wind direction may
not be predictable all the time
Natural Ventilation
Stack pressure driving air flow
Evaluate Infection Control (IC)
Interventions and Measure Impact!!!
Periodic observation of IC practices
Analyze HCW surveillance data
Environmental interventions testing
Chart reviews and audits
Time intervals
Admission to TB suspicion, AFB smears,
sputum collection, laboratory reporting,
initiation of treatment
Naturally ventilatedAirborne Precautions Room
Open window(100%) + Open door 29.3-93.2 ACH
Open window(100%) + Closed door 15.1-31.4 ACH
Open window(50%) + Closed door 10.5-24 ACH
Open window + Open door 8.8 ACH
Y. Li et al. J Hosp Infect. In press.
Rapid decay with windows open:
12 air-changes/hour
0
1000
2000
3000
4000
5000
6000
5 10 15 20 25 30 35
Measurement of Natural Ventilation
Escombe AR, et al. PloS Med 2007;4:e68
Windows & doors openedCO2 release
CO
2co
ncen
trati
on
(p
pm
)
Time (minutes)
Slow CO2 concentration decay with windows closed: 0.5
air-changes/hour
Measurement of Natural Ventilation
Escombe AR, et al. PloS Med 2007;4:e68
0
2000
4000
6000
8000
10000
Absolu
te v
ento
lation m
3/h
Low wind
2 km/h
Wind
>2 km/h
Natural ventilationMechanical
ventilation
Windows & doors:
Fully closed
Partially open
Fully open
Pitfalls in Environmental Control
Setting 1 : Inpatient Chest Disease
Ward
Mixing Fan Window detail
Pitfalls in Environmental Control
Setting 1 : Inpatient Chest Disease
StrengthsMixing fans can help disperse aerosols in
when wind is still
Window area approx 10 m2 on each side
Excellent potential for
cross-ventilation
Patient wearing mask to reduce
aerosol generation
Pitfalls in Environmental Control
Setting 1 : Inpatient Chest Disease
Weaknesses
What happens at night? Shutters closed = zero ventilation
Window potential under-utilized. Only 5% of floor
area on each side.
Modified “negative-pressure”
during SARS
Exhaust fan was mounted in room
Unilateral air flow from nursing area into
room
Smoke test and ajar door test
Exhaust fan mounted on panel
inside the room to create a
negative pressure
Air was sucked out from
nurse station through the room
Single air conditioner per room
Door ajar due to
negative pressure
Copyright ©2007 BMJ Publishing Group Ltd.
Granville-Chapman, J et al. BMJ 2007;335:1293
Sneeze without a Sneeze with a surgical mask surgical mask
Respiratory Protection
Impact of TB Infection Control Measures on
TB Transmission in Chiang Rai, Thailand,
1995 - 1999
TB infection control measures implemented (1996)
Administrative
Infection control plan and SOPs
HCW TST testing, with isoniazid preventive therapy
TB patient education and training for HCW (including lab staff)
Environmental
Natural ventilation maximized in high-risk areas
Negative pressure ventilation in TB isolation rooms
Class II biosafety cabinet for laboratory
HCW respiratory protection (N-95 masks)
Known exposure to infectious TB patient
Laboratory staff processing TB cultures
Yanai H, Limpakarnnanarat K, Uthaivoravit W, et al. Int J Tuberc Lung Dis 2003;7:36-45.
TB rate: 9.3/100 HCWs (1995-1997) to 2.2/100 HCWs (1998-1999)
Conclusions
TB among HCWs occurred from a combination of human error and system error
Education to raise HCWs awareness doesn’t always associated with improved IC behaviors
Although controversial, use of PPD skin test with different cut point might be applicable after post-exposure prophylaxis
Administrative control, respiratory control and respiratory protection can be readily applicable to control TB in developing countries
Thank you very much for your attention
“Kob-Koon-Krub”ขอบคุณครับ
Factors Affecting the
Transmission of Tuberculosis
CASE CONTACT
Site of TB
Cough
Bacillary load
Treatment
Closeness and
duration of contact
Immune status
Previous infection
Ventilation
Filtration
U.V. light
Patient ContactEnvironmental
Post-exposure management
PPD, CXR after exposure
If positive PPD, negative CXR repeat another
PPD in 12 weeks
If positive PPD, positive CXR rule out active
diseases
If PPD negative, CXR positive rule out active
diseases
If PPD negative, CXR negative repeat another
PPD in 12 weeks
Post-exposure management
For Those with 2nd PPD positive
CXR to rule out active disease
If CXR negative, will offer INH for treatment of
latent infection
For Those with 1st & 2nd PPD positive
Depends on the size of PPD test, may offer
treatment for latent infection
Work Practice and
Administrative Controls
Prompt recognition and separation of persons with
infectious TB
Prompt provision of TB and other services (esp HIV,
including HCW)
Infection control plan, including administrative support and
quality assurance
Staff training
Coordination of care
Patient education (cough etiquette; “Ward cough officer”)
Environmental Controls
Natural Ventilation
Free flow of ambient air in and out
through open windows
Negative Pressure Room
Illustrates airflow from outside a room,
across patients’ beds and exhausted
out the far side of the room
Ventilation rates in a
naturally/hybrid- ventilated room under different test conditions
Exhaust fan is:
The door connecting
the room to the corridor is:
The door and windows connecting room to the
balcony and outside air is:
ACH
Off Closed Closed 0.71
Off Closed Open 14.0
Off Open Open 8.8-18.5
On Closed Closed 12.6
On Closed Open 14.6
On Open Open 29.2
Pitfalls in Environmental Control
Setting 2 : Clinic Waiting Area
Exhaust fan and ceiling mixing fan
Vents to clinical exam rooms
Wall-mounted Commercial “air cleaners” with ultraviolet light
and HEPA filtration
Pitfalls in Environmental Control
Do not block windows
Pitfalls in Environmental Control
Setting 2 : Clinic Waiting Area
Strengths
Vents and open doors may allow for cross-ventilation if attached rooms are
well ventilated.
Pitfalls in Environmental Control
Setting 2 : Clinic Waiting Area
Weaknesses
Crowded waiting area without screening, or cough
hygiene No reminders of cough hygiene visible.
Room air cleaners usually useless – can’t clean enough air
Doors closed; exhaust fan not properly used
Respiratory Protection (RP)
Controls
Implement RP program
Isolation rooms
High-risk areas
High-risk procedures
Laboratory testing
Train HCWs in RP
N-95 masks
Fit-testing
What are we doing?
Creating TB fast track started from triage
Creating semi-negative pressure unit for
handle all TB, HIV and EID cases
Creating areas for in-patients admission,
while waiting for budget on negative
pressure rooms
OPD
NAGATIVE PRESSURE
RETURN AIR & EXHAUST AIR
SUPPLY AIREXHAUST FAN
PRE FILTER
MEDIUM FILTER
RECIRCULATING COIL
HIGH STATIC PLUG FAN
C
C
CDU
Ionization
Supply Air
Supply Air
ห้องต
รวจ 1
Supply Air Supply Air
Supply Air
Exh
au
st A
ir
Exhaust A
ir
ห้อง t
rea
tmen
t
ห้องต
รวจ 2
6.00 6.006.00
2.90 2.90 2.90 2.90
Supply
A
ir
Exhaust A
ir
Exhaust A
ir
Exhaust A
ir
ห้องต
รวจ 3
2.902.90