General concepts on tb infection control
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General concepts on TB infection control. Presentation outline. Transmission of TB Hierarchy of Infection Controls Administrative Infection Controls Environmental Controls Personal Respiratory protection HCW protection. The purpose of infection control Program.

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General concepts on TB infection control

Presentation outline

  • Transmission of TB

  • Hierarchy of Infection Controls

  • Administrative Infection Controls

  • Environmental Controls

  • Personal Respiratory protection

  • HCW protection

The purpose of infection control Program

  • To reduce the risk of Mycobacterium tuberculosis transmission to health care workers, patients, and others in the health care facility

Mycobacterium tuberculosis

  • Generated by coughing, sneezing, speaking

  • Remains airborne and spreading air currents

  • Aerobic, desiccation-resistant

  • 1-100 organisms may infect

  • Droplet nuclei, 1-5 

  • Most exposed persons do not become infected

“At risk” health care worker

  • Nurses

  • Physicians, specialists in internal medicine

  • specialists in respiratory medicine (extra risk providing bronchoscopy, caring ventilated patients in ICU)

  • Pathologists

  • Laboratory staff

Fundamentals of Infection Control (1)Hierarchy of Infection Control

Administrative Controls

Environmental Controls

Respiratory Protection

Administrative control measures Administrative Controls

  • Prevention of droplet nuclei containing M. tuberculosis from being generated;

  • Prevention of TB exposure to staff and patients; and

  • Implementation of rapid and recommendeddiagnostic investigation and appropriate treatment for patients and staff suspected or known to have TB.

Administrative control measures Administrative Controls

  • Assign responsibility for TB infection control (IC)

  • Conduct TB risk assessment and develop written TB IC plan, including AII precautions

  • Ensure timely lab processing and reporting

  • Implement effective work practices for managing TB patients

Administrative control measures Administrative Controls

  • Test and evaluate HCWs at risk for TB or for exposure to M. tuberculosis

  • Train HCWs about TB infection control

  • Ensure proper cleaning of equipment

  • Use appropriate signage advising cough etiquette and respiratory hygiene

Administrative control measures Assignment of responsibilities

  • Supervisory responsibility should be delegated to a specific person or infection control team with a leader

  • Should include experts in:

    - infection control

    - hospital epidemiology

    - clinician

    - engineering

  • IC team responsible for all aspects of the IC program

Administrative control measures TB Risk Classifications (1)

All settings should perform risk classification as part of risk assessment to determine need for and frequency of an HCW testing program, regardless of likelihood of encountering persons with TB disease.

Administrative control measures TB Risk Classifications (2)

  • Low risk – Persons with TB disease not expected to be encountered; exposure unlikely

  • Medium risk – HCWs will or might be exposed to persons with TB disease

  • Potential ongoing transmission – Temporary classification for any settings with evidence of person-to-person transmission of M. tuberculosis

Administrative control measures TB Risk Classifications (3)

Administrative control measures TB Risk Classifications (4)

Administrative control measures Implement effective work practices for managing TB patients

  • Infection control plan (including TB) specific to each area within facility, and HCW group based on level of risk

  • Put all procedures in writing plan including:

    • Early detection isolation and treatment of infectious TB patients

    • Patient education

    • Decreasing of cough induction procedures

  • Administrative support for procedures in the plan, including quality assurance;

  • Educate staff about the plan - organization, rationale, and what is expected of them

  • TB screening program for health care workers

  • Education of patients and increasing community awareness; and

  • Coordination and communication between the TB and HIV programs.

Administrative control measures Ensure early identification, diagnostic evaluation, isolation and treatment (2)

  • Focus on high risk groups:

    • contacts,

    • HIV+,

    • positive medical history,

    • People with social and epidemiologic factors)

  • Use appropriate diagnostic methods for TB/MDR-TB

  • Following Isolation protocols and procedures

  • Being sure about adequate effective treatment

Administrative control measures Isolation procedures

  • Designate high-risk areas (isolation rooms) for TB and MDR-TB patients or suspects

  • Establish rules and regulations for isolation (eg. Starting & interruption of isolation, target group, …)

  • Patient education, signed informed consent*

Environmental Controls

  • Second defense in TB IC program, after administrative controls,

  • Control of infection source

  • Dilute and remove contaminated air

  • Control airflow




Ventilation systems

Natural airflow

Technologies for removing or inactivating M. tuberculosis consist ofLocal exhaust ventilation, General ventilation

Air-cleaning methods, e.g., high-efficiency particulate air (HEPA) filtration, ultraviolet germicidal irradiation (UVGI)

Local Exhaust Ventilation

  • Source-control method for capturing airborne contaminants

    • Enclosing device: fully or partially enclosed source; include tents, booths, and biologic safety cabinets (BSCs)

    • External device: source near but outside enclosure

  • Should remove at least 99% of particles before next patient or HCW enters

  • Use

    • for cough-inducing and aerosol-producing procedures

General Ventilation

  • Systems that dilute and remove contaminated air and control airflow patterns in a room

  • Single-pass system preferred for AII rooms

  • Maintain AII rooms under negative pressure

    • Existing settings: ≥6 air changes/hr (ACH)

    • New or renovated settings: ≥12 ACH

  • Recirculation (HEPA filtration, UV irradiation)

  • Engineersmust look after function of ventilation system, to determine airflow and air exchange per hour

Ventilation Airflow

In places with highest risk of infection

  • TB isolation rooms;

  • Bronchoscopy rooms

  • Aerosol rooms

  • Sputum induction rooms

  • TB patient admission rooms

  • Bacteriological laboratory



Air flow measurements

Natural ventilation

Air-Cleaning MethodsHEPA filters

  • Use as supplement to ventilation

  • Used to filter infectious droplet nuclei from the air

  • Must be used

    • When discharging air from local exhaust ventilation booths directly into surrounding room

    • When discharging air from an AII room into the general ventilation system

  • Can be used to clean air that is exhausted to outside

HEPA Filter

Use of filters

Replacement of filter depends on:

- volume and type of exposition

- environmental condition

- Airflow rate

- type of filter

- place of ventilation system

Air-Cleaning MethodsUVGI

  • Kills or inactivates M. tuberculosis

  • Use as supplement to ventilation

  • Not substitute for negative pressure rooms

  • Not substitute for HEPA filtration when air recirculated from AII room into other areas

  • Emphasis on safety and maintenance

  • Occupational exposure limits:

    • Overexposure can cause damage to skin, eyes

    • UVGI systems must be properly installed and maintained

UVGI - cleaning

UVGI - measurements

Respiratory ProtectionGeneral

  • Third level in the IC hierarchy

  • Should be used by persons

    • Entering rooms of suspected/confirmed TB patients

    • Around cough / aerosol-producing procedures

    • In settings where administrative and environmental controls will not prevent the inhalation of infectious droplet nuclei

  • Decision on use of respiratory protection (RP) in labs should be made on case-by-case basis

Respiratory Protection (RP) Controls

  • Implement RP program

  • Train HCWs on RP

  • Train patients on respiratory hygiene

Personal protective equipment

Respirators vs. Masks

Periodic screening of health workers to detect disease at an early stage

  • Each year for employees

  • Medical questionnaire

  • Chest x-ray, PPD test

  • Sputum exam if cough > 2-3 weeks

  • Special consideration for employees with increased individual risk

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