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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 3 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 4 Transmission of TB 5 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 6 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 7 Transmission of M. tuberculosis • Transmission affected by: – Infectiousness of patient – Environmental conditions – Duration of exposure 8 Characteristics of a Patient with TB Disease That 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 Risk of 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 Exposure Non-specific immunity Inadequate Infection (30%) Not everyone who is exposed to TB will become infected 14 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 infectioncontrol 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 infectioncontrol 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 -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 when they : 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 Visitor to Worker to Patient Worker Visitor 22 Patient to • 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 : 1. 2. 3. 4. 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) Group Alcohols Chlorhexidine 2-4% Gram Pos. +++ +++ Gram Neg. +++ ++ M.TB +++ + Fungi +++ + Virus +++ +++ Speed of action fast 60-95% Persistent activity intermediate Persistent activity Rare allergic Rx. Iodophors +++ Phenol derivative Quaternary Ammonium compounds +++ + +++ + ++ + + - ++ + - ++ + + comments intermediate intermediate slow Less irritating than iodine Activity neutralized by nonionic surfactant Used only in combinations with alcohol 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. 30 • 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 N95/ FFP2 35 FFP3 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 36 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 37 Physical factors contributing to poor fitting respirators • • • • • • • • 38 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 39 Find centre of nose piece and bend 40 Open respirator 41 Place straps on back of hand 42 Place respirator on face 43 Pull top strap over head 44 Place top strap on crown of head 45 Pull lower strap over head 46 Place strap at base of head 47 Pinch metal clip around nose 48 Pull respirator over chin 49 Check for major leaks 50 1. Normal breathing 51 2. Deep breathing 52 3. Move head side-to-side 53 4. Move head up-and-down 54 5. Talk non-stop 55 6. Jogging or walking in place 56 7. Normal breathing 57 Smile… you passed 58 Environmental Control Ventilation is: air movement pushing and / or pulling particles & vapors in a controlled manner. • is critical, used for spread control of airborne human resource infectious agents e.g. TB, Varicella Zoster, and Rubella Maybe: • Natural ventilation • Mechanical ventilation • Mixed ventilation Natural ventilation Depends on: • Building location, dimension, window types, operation, design and size • Other openings, doors……….. • External elements (walls, screens) • Wind speed • Other rooms location • Air changes per hour = ACH moving the total amount of air out of a room and replace by fresh air (recommended 12 – 18 ) Natural ventilation(cont.) • Advantages: - High ventilation rate - Low cost (installation & maintenance) - Applicable • Disadvantages: - Climate dependant - Noise pollution - No privacy - Security - No direction control of contaminated air but dilution Mechanical ventilation • Created by fans usage to force air exchange & to drive air flow • Works by generating negative pressure to drive air inwards, all doors & windows kept closed, minimum 12 ACH is maintained Negative pressure rooms: - doors and windows closed - pressure difference 10%, higher to lower, into the room - Evaluation: by smoke test, velocity meter, pressure sensor Mixed Mode Ventilation • Combines mechanical & natural ventilation • Through exhaust fan to increase ACH • Useful in places where natural ventilation is not suitable e.g. very cold climate & when full mechanical ventilated airborne precaution rooms are not available. UVGI UVGI is a form of electromagnetic radiation with wavelengths between the blue region of the visible spectrum and the radiograph region. UVGI has been recommended as a . supplement or adjunct to other TB infection-control and ventilation measures in settings in which the need to kill or inactivate M. tuberculosis is essential Applications of UVGI. UVGI is considered a method of air cleaning because it can kill or inactivate microorganisms so that they are no longer able to replicate and form colonies. UVGI is not a substitute for HEPA filtration before exhausting the air from AII rooms back into the general circulation. UVGI lamps can be placed in ducts, fixed or portable room air-recirculation units, or upper-air irradiation systems . Duct irradiation. Duct irradiation is designed to kill or inactivate M. tuberculosis without exposing persons to UVGI. In duct irradiation systems, UVGI lamps are placed inside ducts to disinfect the exhaust air from AII rooms or other areas in which M. tuberculosis might be present before it is recirculated by the system (less desirable) Upper-air irradiation. In upper-air irradiation, UVGI lamp fixtures are suspended from the ceiling and installed on walls. The base of the lamps are shielded to direct the radiation upward and outward to create an intense zone of UVGI in the upper air while minimizing the levels of UVGI in the lower part of the room where the occupants are located. The system depends on air mixing to move the air from the lower part of the room to the upper part where microbialcontaminatedair can be irradiated Upper-air UVGI can be used in various settings. • AII rooms and rooms in which aerosol-generating or aerosol- producing procedures (e.g., bronchoscopy, sputum induction and administration of aerosolized medications) are performed. • Patient rooms, waiting rooms, corridors, central areas, and other substantial areas in which patients with undiagnosed TB disease could potentially contaminate the air. • Operating rooms and adjacent corridors where procedures are performed on patients with TB disease. . Health and safety issues . Short-term overexposure to UV radiation can caus erythema , photokeratitis (inflammation of the corne and (i.e., inflammation of the conjunctiva) Symptoms of photokeratitis and conjunctivitis include a feeling sand in the eyes, tearing, and sensitivity to light. Photokeratitis and conjunctivitis are reversible conditions, but they can debilitating while they run t course. the health effects of UVGI are usually not evident until after exposure has ended (typically 6– -12 hours later) . ) Upper room UVGI UVGI cleaning UVGI cleaning Routine Maintenance • Clean with alcohol once a month. • Changed every 10 months. • One lamp is efficient for every 12-24 m2 Conclusions • Recommended as one approach to control spread of infectious diseases, TB in particular • Efficacy is maximised if implemented properly and with adequate ventilation in place. HEPA FILTER High-efficiency particulate air filter • Efficient as p-100 filters , it provides a higher level of protection in health care facilities especially in isolation rooms. • Their reusable elements should be cleaned an disinfected after use and the filters replaced in accordance with manufactures recommendations • All used filters should be considered potentially contaminated with infectious material and must be safely discarded. HEPA filtration can be used to supplement other recommended ventilation measures by providing a minimum removal efficiency of 99.97% of particles equal 0.3 μm in diameter. This air-cleaning method is considered an adjuvent to other ventilation measures. Used alone, this method neither provides outside air for occupant comfort nor satisfies other recommended ventilation measures . Portable room-air recirculation systems. Portable room air recirculation units with HEPA filters (also called portable air cleaners) can be considered when 1) a room has no general ventilation system , 2) the system cannot provide adequate ACH , or 3) increased effectiveness in airflow is needed. Effectiveness depends on the ability of the portable room-air recirculationunit to circulate as much of the air in the room as possible through the HEPA filter. . Portable HEPA filtration units should be designed to 1) achieve >12 equivalent ACH , 2) ensure adequate air mixing in all areas of the rooms , and 3) be compatible with the ventilation system. An estimate of the ability of the unit to circulate the air in a room can be made by visualizing airflow patterns (estimating room air mixing]). If the air movement is adequate in all areas of the room , the unit should be effective . One or more lower-efficiency disposable prefilters installed upstream can extend the life of a HEPA filter by at least 25%. Pre-filters should be handled and disposed of in the same manner as the HEPA filter. persons performing maintenance and replacing filters on any ventilation system that is probably contaminated with M. tuberculosis should wear a respirator in addition to eye protection and gloves. Isolation • Infectious patients (MDR-TB) meet their visitors in open air • Separation of infectious patients from non infectious ones • Optimal number of isolation rooms per facility ranges fr0m 1/30 beds in general hospitals to 1/5 beds in acute care hospitals • Patients’ screening in waiting areas to identify potentially infectious patients and prevent HCW exposure Isolation (cont.) • Place TB suspects in separate, well ventilated waiting areas, use surgical masks & minimize waiting time • Use of surgical masks during movement from one place to another • Separation of TB cases in separate building with separate access • Physical means of separation (partitions) Isolation (cont.) • Plastic sheets covering mattresses, beds • Rooms good ventilated, with toilets supplied with soap and paper drying towels • Decrease the number of health staff & visitors authorized to enter following IC precautions • Screen staff periodically (X-ray / Sputum) THANK YOU