Lecture 8: Waterborne Diseases - ZU PDF

Infections of special concern in dentistry 8. Water borne diseases Infection control course 3rd Year, 1st semester Dr Bahaa Badr Weak 4 Intended Learning outcomes (ILOs) After this presenta...

Infections of special concern in dentistry 8. Water borne diseases Infection control course 3rd Year, 1st semester Dr Bahaa Badr Weak 4 Intended Learning outcomes (ILOs) After this presentation, you will be able to: 1. Discuss HIV characteristics, transmission , risk factors for dental team 2. Outline HIV therapy and prevention 3. List waterborne disease agents that may be spread through dental unit water. Reference: 4. Discuss legionnaires disease and pseudomonas Infection control and management of hazardous materials for the dental team, infection in dental clinics 7 Edition; Chris H Miller 5. Discuss prevention of methicillin-resistant Staphylococcus aureus in the dental office. B. Human Immunodeficiency Virus HIV is a member of a group of single-stranded RNA enveloped viruses called retroviruses. Allover the world, 37.9 million infected HIV persons. HIV selectively infects specific T lymphocytes (CD4 lymphocytes). The viral RNA is converted into DNA, which then is incorporated into the chromosomes of the host lymphocyte. HIV undergoes mutations that produce different genetic forms. This genetic variation may explain 1. Different disease severity in different individuals, with some strains being virulent than others. 2. The difficulty in vaccine production for HIV prevention  Human immunodeficiency virus disease HIV produces short acute disease then latent infection (may reach up to 25 years due to antiviral drugs) in which the infected person remains asymptomatic Virus production destroys lymphocytes and yields more viruses that can infect and destroy more lymphocytes. Mechanism of destruction ? When the level of T4 lymphocytes becomes critically low, this progresses to a final phase called acquired immunodeficiency syndrome (AIDS). HIV disease involves destruction of the immune system of the body making an individual susceptible to opportunistic infections and cancers  Transmission of HIV HIV can be killed easily when outside the body. All forms of heat and gas sterilization readily kill it. The virus is also killed by commonly surface disinfectants HIV is transmitted primarily from an infected person through the following routes: 1. Intimate sexual contact 2. Blood transfusion, blood products or blood- contaminated items (e.g., sharing intravenous drug) 3. Perinatal contact (from infected mother to child) Risk for the Dental Team Occupational risk: The risk of HIV disease transmission from dental patient to dentist is low; nevertheless, some small potential exists for this to occur Two important risk factors: A. Risk of transmission increases when hollow bore needles are involved, especially if the needles have been inserted into an artery or vein, or have caused a deep tissue injury. B. Another important risk factor is whether the source patient with high or low viral load In general, the greatest concentration of HIV in blood (viral load) occurs soon after infection (acute retroviral syndrome) and during the AIDS stage of HIV disease. Prevention of HIV infection Pre exposure prophylaxis drugs(PrEP): reduce the risk of HIV infection in those with high risk by 92%. Post exposure prophylaxis drugs (PEP): may keep one from becoming infected, but must be started within 72 hours after a possible exposure 1. Sexual Contact a. limiting sexual activities to one uninfected partner who does not have any other sex partners b. Safe sex practices, such as the use of condoms to eliminate contact of with body fluids that may contain HIV 2. Blood Contact 1. Injection-drug abusers must not use blood- contaminated needles.  Prevention of HIV infection 2. Continued screening for HIV-infectivity of blood for transfusion or blood products 3. All members of the dental team must protect themselves from exposure to blood and saliva of patients and also must prevent their blood or body fluids from coming into contact with the patients. 4. Gloves, mask, and protective eyewear must be used during the care of all patients to prevent direct or indirect contact with body fluids 3. Perinatal  Monotherapy or combined drug treatment used to reduce perinatal transmission of HIV to infant significantly  Side effects of drugs commonly develop in the mothers  Waterborne disease Waterborne pathogens is those pathogens which transmitted by contaminated water Definition of waterlines of dental clinics:  Group of thin plastic tubes which carry water from its sources to the patient mouth as air/water syringes and high speed hand pieces The level of bacteria in dental unit water is much greater than that of tap water due to 1. Water sits stagnant in lines over night and in weekends 2. Optimal breeding ground for microorganisms 3. Generation of aerosols under pressure  Waterborne disease agents When waterborne bacteria enter the dental unit, they attach to the inside line walls forming bacterial biofilm, that releases bacteria as the water flows out of the lines Although different types of bacteria may be present in dental unit water, three opportunistic pathogen are of particular interest; 1. Legionella pneumophila 2. Pseudomonas aeruginosa 3. Mycobacteroides 1. Legionnaires Disease L. pneumophila is a gram-negative bacilli that causes Legionnaires pneumonia (Atypical pneumonia) L. pneumophila Legionnaires infection results from inhalation of water aerosols from water handling systems rather than from lakes or streams Water handling systems include air-conditioning, shower heads, fountains and dental hand-piece or air/water syringes  Complications as pneumonia mostly in the elderly patients and those with weakened immune defenses 10% of dental offices have Legionella in the dental unit water  An 82-year-old woman was reported as died from Legionnaires disease contracted from a dental office Person to person spread has not been documented  Treatment is Erythromycin  2. Pseudomonas aeruginosa Infection Improperly maintained eyewash stations may result in a buildup of opportunistic waterborne organisms, such as Pseudomonas which can cause eye and oral infections A reported two cancer-weakened dental patients acquired oral infections with P. aeruginosa that originated from dental unit water 3. Mycobacterium abscessus (Mycobacteroides): is a waterborne bacterium that may be present in dental unit water  Mycobacteroides most commonly causes oral infection and chronic lung infection Source of contamination in dental water unit 1. The main water piped dental unit (original source of water) or bottled water system; less common 2. Most common source is Retraction; the suck back of patient`s saliva to the lines due to lack of effective valves  Retraction of oral bacteria back into the hand-piece, air/water syringes occurs through slow down phase at the end of flushing  Dental units should contain anti-retraction valves, but these valves fail periodically so maintenance is important Transmission of oral bacteria in between patients  Quality of dental unit water The CDC (Centers for Disease Control and Prevention) indicate the following: 1. Dental unit water should not be used to irrigate open surgical sites (use instead deionized water or saline) 2. Water lines should be flushed at the beginning and at the end of the day to reduce the number of waterborne bacteria that may accumulated in the water 3. Water lines should be flushed between patients to reduce the number of oral microorganisms that may have been retracted into the lines after each patient 4. Bacterial count in dental unit water should be ≤ 500 CFU/ml  Methicillin-resistant staphylococcus aureus MRSA is a bacterium resistant to β-lactams antibiotics, that include methicillin and others, such as, penicillins, and Cephalosporins. 1. Community acquired MRSA: are mainly skin infections that appear as pustules or boils and often have pus. Skin infections commonly occur at skin trauma, such as cuts and abrasions, and areas of the body covered by hair (e.g., back of neck, and beard area of men). 2. Hospital acquired MRSA: it cause severe life- threatening infections occur among health care patients that cause bloodstream infections, surgical site infections, and pneumonia Recommendations to prevent MRSA MRSA present in dental personnel as carriers, and also in environment as dental operatory surfaces  MRSA are spread by having direct contact with someone’s skin infection or using a personal items of an infected person Factors that increase the spread of MRSA skin infections: 1. Close skin-to-skin contact specially opened skin, such as cuts or abrasions 2. Contaminated items and surfaces 3. Crowded living conditions, and poor hygiene Procedures that prevent the spread of MRSA include: 1. Hand hygiene 2. Wearing appropriate personal protective equipment 3. Cleaning and disinfecting of clinical contact surfaces and contaminated reusable items 1. Which of the following is not a 2. How does HIV cause AIDS mode of spread of HIV disease a. It destroys the liver a. Percutaneous through b. It destroys the body’s defenses contaminated injuries against diseases b. Inhalation c. It destroys the ability to control c. Blood transfusion muscle action d. Sexual activities d. It paralyzes the body e. From infected mother to child at e. It causes destruction of lymphoid birth organs 3. What bacterium in dental unit 4. An opportunistic pathogen causes water has been shown to cause oral disease only: disease in immunocompromised a. when it is swallowed patients? b. under special circumstances that a. Streptococcus pyogenes give it an advantage to multiply to b. Legionella pneumophila harmful levels c. Pseudomonas aeruginosa c. when a person has been treated d. Mycobacterium tuberculosis with an antibiotic e. Corynebacterium diphtheria d. in persons who have no other infectious disease