Tuberculosis And Airborne

Tuberculosis Among Thai

Healthcare Workers:

a Human or System Failure

Anucha Apisarnthanarak, M.D.

Assistant Prof.

Thammasat University Hospital

[email protected]

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



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



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


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


Do not block windows



Strengths

Vents and open doors may allow for cross-ventilation if attached rooms are

well ventilated.



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

Health & Medicine

Tuberculosis And Airborne