Tuberculosis And Airborne


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Tuberculosis And Airborne

  1. 1. 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
  2. 2. 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
  3. 3. 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.
  4. 4. 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
  5. 5. Transmission
  6. 6. 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.
  7. 7. What we did?
  8. 8. Postexposure Detection of Mycobacterium tuberculosis Infection in Health Care Workers in Resource-Limited Settings No. (%) of patients Second TST With M.turberculosi Increase of s infection at 2- Initial TST Initial TST No change >10 mm year follow-up reaction size (n = 95) (n = 87) (n = 8) (n = 6) > 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) Apisarnthanarak A, et al. Post-exposure detection of TB in Thai HCWs. CID, 2008
  9. 9. 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
  10. 10. Among Thai HCWs and in other resource-limited settings Khawcharoenporn T, Apisarnthanarak A, et al. TST among MS with prior BCG. ICHE, 2008 (in press)
  11. 11. Among HCWs around the world Study TB case TST BCGV effect location rate per Definition BCGV reactions Effect on 1st step TST Booster effect on 2nd step year 100,000 of BCGV rate 10 mm. positivity 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, 172 BCGV scars 83% 79% No, at cut-off level 10 mm. ND 1997 and recall Malaysia, 66 Recall 99% 78% No, at cut-off level 10 ND 2001 and 15 mm. Mexico, 52 BCGV scars 84% 64% Yes, at cut-off level 10 mm. ND 1998 Thailand, 64 BCGV scars 77% 68% Yes, at cut-off level 10 mm. ND 1996 No, at cut-off level 15 mm. Turkey, 96 BCGV scars 93% 83% Yes, at cut-off level 10 mm. ND 2002 and recall Uganda, 402 BCGV scars 41% 57% No, at cut-off level 10 mm. ND 2001 Our study 85 BCGV scars 58% 62% Yes,at cut-off level10-19mm. Yes, for 6-9 mm. increase No, at cut-off level 20 mm. No, for  10 mm. increase Khawcharoenporn T, Apisarnthanarak A, et al. TST among MS with prior BCG. ICHE, 2008 (in press)
  12. 12. 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
  13. 13. 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
  14. 14. 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.
  15. 15. Teaching Point “Good knowledge doesn’t always translate into good IC practices and behaviors…additional interventions are needed”
  16. 16. Is this a system error? 7000 Laboratory 6977 Medicine ED/ICU Rate per 100,000 HCWs All hospital Other areas 2000 1500 1418 1163 1000 932 709 792 709 581 709 500 488 466 233 334 187 60 187 121 0 181 1994 1995 1996 1997 Year Alonso-Echanove, et al. TB among HCWs in Peru. CID, 2002
  17. 17. Evaluation of potential risk factors for Mycobacterium tuberculosis infection among health care workers (HCWs) from clinical and laboratory areas Clinical areas Laboratory areas n/N PRR P n/N PRR P Variable (95% Cl) (95% Cl) Employment in medicine 92/121 2.1(1.5-2.9) <.001 _ _ _ wards Helped in sputum 57/71 1.5(1.2-1.9) <.001 1/1 _ NS collection Contact with person with 106/142 3.2(1.9-5.3) <.001 34/39 1.9(1.3-2.7) <.001 active tuberculosis Duration of 102/156 1.5(1.0-2.2) .01 37/52 1.2(0.8-1.8) NS employment≥1 year Use of common staff 106/171 1.1(0.8-1.7) NS 41/46 2.7(1.6-4.5) .001 areas
  18. 18. 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.”
  19. 19. How to develop intervention to reduce TB transmission in resource limited setting?
  20. 20. 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
  21. 21. 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
  22. 22. Pathway for avian influenza is well established
  23. 23. 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
  24. 24. Don’t be bias: Thailand is a model country for WHO TB intervention campaign
  25. 25. 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
  26. 26. 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
  27. 27. Natural Ventilation Door Air Mixing and Directional Flow
  28. 28. Direction of Natural Ventilation or Incorrect Working Locations Direction of Natural Ventilation or Correct Working Locations
  29. 29. However, wind direction may not be predictable all the time Natural Ventilation Stack pressure driving air flow
  30. 30. 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
  31. 31. Naturally ventilated Airborne 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.
  32. 32. Measurement of Natural Ventilation CO2 release Windows & doors opened 6000 5000 CO2 concentration 4000 (ppm) Slow CO2 concentration decay Rapid decay with 3000 with windows closed: 0.5 windows open: air-changes/hour 12 air-changes/hour 2000 1000 0 5 10 15 20 25 30 35 Time (minutes) Escombe AR, et al. PloS Med 2007;4:e68
  33. 33. Measurement of Natural Ventilation 10000 8000 Windows & doors: Absolute ventolation m3/h Fully closed 6000 Partially open Fully open 4000 2000 0 Low wind Wind 2 km/h >2 km/h Mechanical Natural ventilation ventilation Escombe AR, et al. PloS Med 2007;4:e68
  34. 34. Pitfalls in Environmental Control Setting 1 : Inpatient Chest Disease Ward Mixing Fan Window detail
  35. 35. Pitfalls in Environmental Control Setting 1 : Inpatient Chest Disease Strengths Excellent Mixing fans can help Window area approx potential for disperse aerosols in 10 m2 on each side cross-ventilation when wind is still Patient wearing mask to reduce aerosol generation
  36. 36. Pitfalls in Environmental Control Setting 1 : Inpatient Chest Disease Weaknesses Window potential under- utilized. Only 5% of floor area on each side. What happens at night? Shutters closed = zero ventilation
  37. 37. 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
  38. 38. Exhaust fan mounted on panel inside the room to create a negative pressure Air was sucked out from nurse station through the room Door ajar due to negative pressure Single air conditioner per room
  39. 39. Respiratory Protection Sneeze without a Sneeze with a surgical mask surgical mask Granville-Chapman, J et al. BMJ 2007;335:1293 Copyright ©2007 BMJ Publishing Group Ltd.
  40. 40. 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 TB rate: 9.3/100 HCWs (1995-1997) to 2.2/100 HCWs (1998-1999) Yanai H, Limpakarnnanarat K, Uthaivoravit W, et al. Int J Tuberc Lung Dis 2003;7:36-45.
  41. 41. 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
  42. 42. Thank you very much for your attention “Kob-Koon-Krub” ขอบคุณครับ
  43. 43. Factors Affecting the Transmission of Tuberculosis Patient Environmental Contact CASE CONTACT Site of TB Ventilation Closeness and Cough Filtration duration of contact Bacillary load U.V. light Immune status Treatment Previous infection
  44. 44. 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
  45. 45. 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
  46. 46. 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”)
  47. 47. 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
  48. 48. Ventilation rates in a naturally/hybrid- ventilated room under different test conditions The door connecting The door and windows Exhaust connecting room to the ACH the room to the fan is: corridor is: balcony and outside air is: 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
  49. 49. Pitfalls in Environmental Control Setting 2 : Clinic Waiting Area Vents to clinical exam rooms Wall-mounted Commercial “air Exhaust fan and cleaners” with ultraviolet light ceiling mixing fan and HEPA filtration
  50. 50. Pitfalls in Environmental Control Do not block windows
  51. 51. 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.
  52. 52. Pitfalls in Environmental Control Setting 2 : Clinic Waiting Area Weaknesses Crowded waiting area without screening, or cough hygiene No reminders of cough hygiene visible. Doors closed; exhaust fan not Room air cleaners usually properly used useless – can’t clean enough air
  53. 53. 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
  54. 54. 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
  56. 56. Exhaust Air 2.90 6.00 ห้อง treatment 2.90 Exhaust Air Supply Air Exhaust Air 2.90 ห้องตรวจ 1 Supply Air 6.00 ห้องตรวจ 2 Supply Air 2.90 Exhaust Air Supply Air Exhaust Air 2.90 ห้องตรวจ 3 Supply Air 6.00 2.90 Supply Air