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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.
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Infection Control For Tuberculosis Dr. Amany Ibrahim Specialist of Infection Control Abbassia Chest Hospital
Etiology M. tuberculosis M. bovis M. africanum M. microti M. canettii M. caprae M. pinnipedii
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
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
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
Transmission of M. tuberculosis • Transmission affected by: • Infectiousness of patient • Environmental conditions • Duration of exposure
Characteristics of a Patient with TB DiseaseThat 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 Riskof 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 Non-specific immunity Exposure Inadequate Not everyone who is exposed to TB will become infected Infection (30%)
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 infection-control 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 infection-control 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 con---
-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 whenthey : 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 Patient to Worker to Visitor to Patient Worker Visitor
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 : • 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)
WHO Recommended Guidelines for Hand Washing and Hand Antisepsis
Wash hands with soap and water in the following situations: • 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.
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 FFP3 N95/ FFP2
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
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
Physical factors contributing to poor fitting respirators • 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
