Microbiology Final Exam 01 PDF

Healthcare epidemiology: The study of the occurrence, determinants, and distribution of health and disease within healthcare settings (studying the disease at the population level). It covers different healthcare settings, such as hospitals, clinics, rehabilitation centers, long-term care fa...

Healthcare epidemiology: The study of the occurrence, determinants, and distribution of health and disease within healthcare settings (studying the disease at the population level). It covers different healthcare settings, such as hospitals, clinics, rehabilitation centers, long-term care facilities, and hospices (care of terminally-ill patients). It aims to protect patients, healthcare personnel, and visitors from acquiring infection in healthcare facilities. Healthcare epidemiology covers such practices and activities as: › Infection prevention and control (IPC) )‫ (ضبط العدوى‬: Prevent the transmission of infections between the potential source and the potential targets. › Surveillance measures )‫(إجراءات المسح اإلحصائي‬: Systematic collection, analysis, and interpretation of health data that are essential to the public health practice such as; presence of microbes, risk factors and diseases. › Risk reduction programs focusing on device (urinary catheters) and procedure management (procedures done in the orthopedic operating rooms especially that involve the artificial organs/ joints). › Policy development and implementation. › Education of healthcare personnel in infection control practices and procedures. › Cost-benefit assessment (economic analysis) of prevention and control programs. Some important definitions: Healthcare-onset infections: are those appearing in healthcare settings regardless the source. Community-associated infections: are those acquired outside healthcare facilities. Healthcare-associated (nosocomial) infections (HAIs): are those acquired inside healthcare facilities. They include: › Infections that were not present or incubating at the time of admission. › Community-onset infections appearing within 14 days of discharge. Iatrogenic infections: are those occurring due to medical or surgical intervention (during the intervention; during the insertion of the catheter). Notes: Onset — where was the patient when the symptoms and signs appeared. Associated — where was the patient when the microbes invaded his body (the source). The term ‘-acquired’ might be used by some in place of ‘-associated’. Nosocomial infections (healthcare-associated infections): The most common types of nosocomial infections are: › Urinary tract infections (especially when using urinary catheter). › Surgical wound infections. › Lower respiratory tract infections. › Bloodstream infections. 1  Major factors that contribute to Nosocomial Infections: › Increased number of drug-resistant pathogens which is associated with the overuse of antibiotics, disinfectants and antiseptic. And also with the diversity of microbesin healthcare facilities (many different patients = many different microbes). › Increased number of immunocompromised patients. › Failure of healthcare personnel to follow infection control guidelines. Microbial causes of nosocomial infections: › Nosocomial infections might well be endogenous (source: normal flora) as well as exogenous. › Pathogens most often involved in such infections are: 1. Gram-positive cocci: - Staphylococcus aureus: Cause skin, soft tissues, bone. joint and heart infectious disease! Especially methicillin-resistant S. aureus (MRSA). - Coagulase-negative staphylococci: Low pathogenicity (virulence) comparing to S.aureus, but it can form biofilms because their ability to attach with artificial surfaces (prosthetic devices/ intravascular catheters (central lines)) which can cause diseases. Coagulase test is used to Important part of skin normal flora. differentiate Staphylococcus aureus which produce the Especially methicillin-resistant S. epidermidis (MRSE). enzyme coagulase (positive), - Enterococcus species: Especially vancomycin-resistant enterococci (VRE). from other cocci. 2. Gram-negative bacilli: - Enterobacterales: order (‫ )رتبة‬of gram-negative bacilli! (E.coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter species.). - Pseudomonas aeruginosa. - Acinetobacter species. Multidrug-resistant gram-negative bacilli (MDR-GNB): - Major global public health concern. - Include: 1- ESBLs: bacteria which produce extended spectrum β-lactamases → inactivate β-lactams. 2- CPEs: carbapenemase-producing Enterobacteriaceae that breakdown carbapenem imipenem, meropenem (antibiotics). 3. Clostridioides difficile: Spore-forming, anaerobic, gram-positive bacillus. Part of the colonic normal flora. An important cause of antibiotic-associated diarrhea AAD (due to overuse of antibiotics) and pseudomembranous colitis PMC (which can be sever and lead to death!). Risk factors for contracting nosocomial infections (make them targets) include: › Extremes of age (newborns (immature immune system) and elderly (degenerated immune system)). › Labor and delivery. › Surgical and burn patients (easier access of microbes to the deeper tissue because of barrierdisruption such as skin). 2  › Chronic diseases and conditions: - Cystic fibrosis → thick airway secretions (mucus) = easy colonization of microbes (in respiratory tract). - Renal dialysis → using catheters/ suppressing immune system! - Paralysis → lead to pressure ulcers which provide easier access to microbes. - Diabetes, Cancer and Immunodeficiency. › Therapeutic modalities affecting the immune system (steroids, anticancer drugs, immunosuppressive medications, radiotherapy). › Indwelling devices (endotracheal tubes, central venous or arterial catheters, urinary catheters, synthetic implants). Steps to fight antimicrobial resistance in healthcare settings: Precaution Protocols: The precaution protocols implemented in healthcare settings to fight infection spread are divided into: Protocols which highlight the patient as a potential target of infection; › Protective isolation (neutropenic isolation or reverse isolation) is primarily used in immunocompromised patients to decrease the risk of their exposure to pathogens. Protocols which highlight the patient as a potential source of infection; Theses source isolation protocols are further divided into: › Standard precautions: Implemented on all patients in all healthcare settings regardless of the degree of suspicion of the presence of an infectious agent. Aim to minimize transmission of infection through body fluids (except sweat because it doesn’t contain significant microbes), non-intact skin and mucous membranes. 3  › Transmission-based precautions: Precautions additional to the standard ones are needed to minimize risk of infection spread. Used for patients who are known or suspected to carry an epidemiologically important infectious agent. Include airborne, droplet, and contact precautions. 1. Airborne precautions: Suspected particles expelled from the respiratory tract have a diameter of 5 μm or less. These particles are light enough to remain in air for a significant period of time, travel relatively far (>1 m), and potentially reach alveoli upon inhalation. Diseases transmitted through such droplets: Pulmonary tuberculosis, CoViD-19, measles and chickenpox. 2. Droplet precautions: Suspected particles expelled from the respiratory tract have a diameter of more than 5 μm. These particles are relatively heavy so they fall from air faster, travel for only a short distance ( outside of the room. Air can leave the room without circulating back in. Airborne particle that originates in the room will be filtered out and any airborne particle from outside will not enter the room. Protect patient from infections and disease. STANDARD AIRBORNE DROPLET PRECAUTIONS CONTACT PRECAUTIONS ACTIVITY PRECAUTIONS PRECAUTIONS PATIENT Single room not  Single room with  Single room preferred, Single room preferred, PLACEMENT required negative pressure otherwise cohort otherwise cohort patients ventilation patients with same with same etiological  Non-essential etiological diagnosis diagnosis susceptible people  Provide at least 1 m of should be excluded separation between patients in cohort PATIENT Minimize time outside, Minimize time outside, at  Minimize time outside TRANSPORT - at which time patient which time patient should  Minimize contact with should wear mask wear mask nearby environmental items It’s not totally safe to cohort patients with same etiological diagnosis, because they may be the same microbes but different strains! Still it’s safer than cohort patients with different etiological diagnosis 6 3. Personal Protective Equipment (PPE): Used in both source and protective isolation and include: › Gloves. › Aprons and gowns. › Eye protection (goggles, face shields). › Respiratory protection: such as masks and respirators. The respirators are denoted by either the ‘N’ (American system) or the ‘FFP’ (European system) systems, and they are classified according to their filtration efficiency. › Caps and shoe covers. Care must be taken to follow the proper procedures and sequences for wearing and removing PPE as well as maintaining hand hygiene meanwhile! STANDARD AIRBORNE DROPLET CONTACT ACTIVITY PRECAUTIONS PRECAUTIONS PRECAUTIONS PRECAUTIONS GLOVES When likely to touch blood, As per Standard As per Standard When entering body fluids and Precautions Precautions isolation room contaminated items APRONS AND GOWNS When soiling likely (i.e. As per Standard As per Standard When entering during procedures likely to Precautions Precautions isolation room generate contamination with blood and body fluids) EYE PROTECTION During procedures likely to - As per Standard As per Standard As per Standard (Face shield/ Goggles) generate a splash or spray of Precautions. Precautions Precautions blood or body fluids - Non-essential Remember that nasal cavity its continuity with the conjunctiva! susceptible people should be excluded RESPIRATORY Wear mask during Wear respirator when Wear mask when As per Standard PROTECTION procedures likely to generate entering isolation room entering isolation Precautions (Masks/ Respirators) contamination with aerosols (for the protection room (e.g. suctioning intubation, against small-sized dentistry) microbes) Face Shield and Mask smaller filter pores’ size Proper Procedure for Glove Removal 7  Proper Sequence for Wearing PPE: Proper Sequence for Removing PPE: From the highest contaminated equipment to the least one* 4. Personal care equipment: › When handling patient-care equipment which are visibly soiled or possibly contaminated with blood or body fluids, use the PPE appropriate to the level of that contamination. › In order to minimize the risk of infection spread, use disposable equipment whenever possible. › Otherwise, the equipment should be classified according to the risk of infection they carry in order to decide on the proper level of reprocessing needed (sterilization, disinfection, cleaning). › For that purpose, we use the Spaulding system to classify these items into: - Critical items (used with sterile body sites) which need sterilization. - Semi-critical items (used with non-intact skin and mucus membranes) which need disinfection. - Non-critical items (used just with intact skin) which need disinfection. Examples of categories of items and disinfection agents in relation to the spaulding system Category Examples Critical Surgical Instruments, items Biopsy Instruments. Agents for Steam, Ethylene oxide, Hydrogen sterilization peroxide gas plasma Semi-critical Respiratory therapy equipment, items Anesthesia equipment, Endoscopes Agents for Glutaraldehyde, Ortho- high-level Phthalaldehyde, Hydrogen peroxide, disinfection Peracetic acid with Hydrogen peroxide Non-critical ECG machines, Oximeters, Blood items pressure cuffs, Crutches, Bedpans Agents for 70-90% Ethyl or Isopropyl alcohol, intermediate- Sodium hypochlorite, or low-level Germicidal detergent solutions (e.g. disinfection Phenolic, Iodophor, Quaternary Ammonium) 8 5. Laundry: Instructions to carry out proper laundry of linen and bedding include: › Remove large amounts of solid waste (stool) while using appropriate PPE and dispose waste in a toilet before placing in a laundry bag. › Place contaminated linen in laundry bags with minimal manipulation. › Avoid sorting linen in patient-care areas. › Wash and dry linen according to the facility’s routine standards and procedures. › Wipe bedding with plastic covers with a neutral detergent. › Mattresses without plastic covers but which are contaminated with body fluids should be steam cleaned (preferable) or manually washed. 6. Environmental Cleaning and Waste Disposal: Instructions to carry this properly include: › Comply with the hospital’s procedures for the routine care, cleaning and disinfection of environmental surfaces (bed-rails, bedside tables, commodes, sinks, doorknobs). › Avoid aerosol-generating practices (dry-dusting, sweeping, vacuum cleaning, spraying disinfectants). › Comply with the hospital’s procedure for classification and ensuing proper handling of waste material. 7. Prevention of Needles tick and Sharps’ Injuries; - Injuries sustained due to sharps may cause transmission of such blood borne pathogens as HBV, HCV and HIV. - Such sharp instruments include needles, scalpel blades and broken glass. - Instructions to minimize the risk of such injuries include: › Take care to prevent injuries when using sharps, handling them after procedures, and while cleaning and disposing of used ones. › Don’t remove used needles from disposable syringes by hand, and do not bend, break or otherwise manipulate used needles by hand. › Don’t use reusable syringes. › Never recap used needles. › Never direct the point of a needle towards any part of the body except before injection. › Use sharp devices with safety features. › Dispose of sharps in appropriate containers which should be rigid, puncture-resistant, leak- proof, disposable, clearly marked with a biohazard label, and located as close as practicable to the area in which the items are used. 9  Classification and handling of hospital waste: Some sharp instruments used in healthcare: Sharps containers in different sizes: Sharp Devices with Safety Features: 12 10