Y khoa, dược - Principles of asepsis

32Principles of Asepsis32-2Learning Outcomes32.1 Explain the historical background of infectious disease prevention.32.2 Identify the types of microorganisms that cause disease.32.3 List some infectious diseases, and identify their signs and symptoms.32.4 Discuss the importance of preventing antibiotic resistance in a health-care setting.32.5 Describe ways you can help prevent antibiotic resistance in health-care settings.32-3Learning Outcomes (cont.)32.6 Explain the disease process.32.7 Explain how the body’s defenses protect against infection.32.8 Describe the cycle of infection.32.9 Identify and describe the various methods of disease transmission.32.10 Explain how you can help break the cycle of infection.32-4Introduction Antibiotic-resistant organismsImportance of patient education on the proper use of antibioticsYou will learn about:Disease-causing microorganismsHow the body fights diseaseWays infections occurOur bodies are amazing structures that defend us against infections undernormal circumstances32-5History of Infectious Disease PreventionThroughout history people have attempted to discoverCauses of infectionHow to prevent infectionsHow to treat infections32-6History of Infectious Disease Prevention (cont.) ScientistContributionEdward Jenner (1749–1823) Developed first effective  vaccine Used cowpox to vaccinate  against smallpox Ignaz Semmelweis (1818–1865) and Oliver Wendell Holmes (1809–1894) Promoted handwashing as a means of reducing the spread of puerperal fever to women in childbirth 32-7History of Infectious Disease Prevention (cont.) Scientist ContributionLouis Pasteur (1822–1895) Helped develop the germ theory of infectious disease, stating that disease is caused by microorganismsJoseph Lister (1827–1912)Helped develop germ theory Introduced aseptic techniques through the use of antiseptics on wounds, surgical sites, and surgical instruments32-8History of Infectious Disease Prevention (cont.) Scientist ContributionRobert Koch (1843–1910)Developed a set of proofs, known as Koch’s postulates, claiming that microbes cause diseaseSir Alexander Fleming (1881–1955) Discovered penicillin 32-9History of Infectious Disease Prevention (cont.) Remarkable advances in the past centuryThreat of infection still presentNew infectious diseasesAIDSEbolaResistant diseasesMRSAVRSAMultidrug-resistant TB32-10Apply Your KnowledgeWhy is the threat of infection still present even though great advances have been made in controlling infections over the past century?ANSWER: The threat of infection is still present because of new diseases and diseases that have become resistant to treatments.Right!32-11Microorganisms and DiseaseMicroorganisms live all around usPathogens Microorganisms capable of causing diseaseEvade host defensesPeople avoid infections most of the timeMany microorganisms are beneficial or harmlessNormal defenses resist infectionConditions are not favorable for pathogens to grow and be transmitted32-12Microorganisms and Disease (cont.)Classification Characteristics Example DiseasePrions*Infectious particle made of proteinNo nucleic acidReproduction unknownPr P Creutzfeldt-Jakob diseaseMad cow disease * Experts disagree as to whether prions are directly responsible for disease or merely aid an unknown agent in causing disease.32-13Microorganisms and Disease (cont.)Classification Characteristics Example DiseaseVirusesDNA or RNA surrounded by protein coatReproduced in living cellsVery smallVaricella-zoster virusChickenpox Bacteria Single-celled Reproduce quickly Mostly asexual  reproductionVibrio choleraeCholera32-14Microorganisms and Disease (cont.)Classification Characteristics Example DiseaseProtozoans Single-celled Reproduction  mostly asexualEntamoeba histolyticaAmebic dysenteryFungi Multicellular Reproduction is sexual and asexualCandida albicansCandidiasisHelminths Multicellular  parasitic Contain specialized organs Sexual reproductionEnterobius vermicularisPinworms32-15Apply Your KnowledgeIn many cases, we avoid contracting infections when exposed to microorganisms. What are the reasons for this?ANSWER: This is because:many microorganisms are beneficial or harmlesswe have normal defenses to resist infectionconditions are not favorable for the pathogen to grow and be transmitted. Correct!32-16Infectious Diseases Knowing signs and symptoms of common infectious diseases can help protect against exposure32-17Infectious Diseases (cont.)Chickenpox (Varicella) Contagious viral infection Incubation period of 7 to 21 days Itchy rash  fluid-filled blisters Slight fever, headache, general malaise Spread by direct, indirect, droplet, or airborne transmission Isolate until all blisters have scabbed over 1996 – live vaccine approved32-18Infectious Diseases (cont.)Common coldViral infections of upper respiratory tractNo isolation neededCommonsense precautions to prevent spread Use tissues when coughing or sneezing Wash hands frequently Use disposable dishware, if possibleIncubation – 2 to 3 days32-19Infectious Diseases (cont.)Croup Most often caused by a virusCharacterized by a harsh, barking cough, difficulty breathing, hoarseness, and low-grade feverMost common in infants and young childrenSymptoms lessened by humidification of air, rest, and clear fluidsCommonsense precautions to prevent spread32-20Infectious Diseases (cont.)DiphtheriaBacterial infection of nose, throat, and larynxSymptoms: pain, fever, respiratory obstructionIncubation – 2 to 5 daysIsolation requiredAntibiotic therapy (fatal if untreated)Immunization available32-21Infectious Diseases (cont.)Epstein-Barr Virus Common human virus95% of adults have had virus35 – 50% of teens develop mononucleosisSymptoms – fever, sore throat, swollen lymph nodesVirus remains dormant for lifeOccasionally reactivates as tumors32-22Infectious Diseases (cont.)Haemophilus Influenzae Type B Bacterial infections in infants and young childrenSpread – direct, indirect, and droplet transmissionIncubation – 3 daysUpper respiratory symptoms, fever, drowsiness, body aches, diminished appetite Monitor closely – bacterial meningitis32-23Infectious Diseases (cont.)HepatitisViral infection of liverSpread through blood or fecal-oral route HIV/AIDS Human immunodeficiency virus Acquired immune deficiency syndrome32-24Infectious Diseases (cont.)Influenza (Flu)Symptoms – fever, chills, headaches, body aches, upper respiratory congestionIsolation and commonsense precautionsVaccinesLive, attenuated virus – nasal sprayInactivated virus – IM injectionAnnual vaccinationPeople at risk for complicationsPeople older than 50 years oldPeople in close contact with persons at risk for complications32-25Infectious Diseases (cont.)Measles (Rubeola)Infectious viral diseaseSpread by droplets or direct transmission Initial symptom of fever develops 8 to 13 days after exposure, followed by a characteristic itchy rash 14 days after exposureIsolation for 7 days after rash appearsKeep children under 3 years old away from anyone with the diseaseReportable to state or county health dept.32-26Infectious Diseases (cont.)MeningitisInflammation and infection of protective coverings of brain and spinal cord and the fluids around themViral – milder form Clears in 1 to 2 weeks without treatment Aseptic meningitis32-27Infectious Diseases (cont.)MeningitisBacterial – serious, life-threatening, requiring immediate treatmentVaccination available for people in high-risk groupsSymptoms – red, blotchy rash, confusion, delirium, light sensitivity, headache, fever and chills, nausea and vomiting, sleepiness, stiff neckMay spread through exchange of respiratory and throat secretions Reportable to state or county health dept.32-28Infectious Diseases (cont.)MumpsViral infection Primarily affects salivary glandsIncubation – 2 to 3 weeksPain related to inflammation of parotid gland and feverIsolate until glandular swelling stopsReportable to state or county health dept. 32-29Infectious Diseases (cont.)Pertussis (Whooping Cough)Highly contagious bacterial infection of respiratory tractSymptoms – fever, sneezing, runny nose, quick short coughs, characteristic “whoop” during inhaled breath following coughing fitIsolate for 3 weeks following onset of spasmodic coughsReportable to state or county health dept.32-30Infectious Diseases (cont.)RoseolaRose-colored rash possibly caused by human herpes virusInfants and young childrenIncubation 5 to 15 daysSymptoms – sudden, high fever; sore throat; swollen lymph nodes; rashRubella (German Measles) Highly contagious viral disease Direct or droplet transmission Incubation 16 to 18 days Symptoms – fever and itchy rash Vaccination available Reportable 32-31Infectious Diseases (cont.)Streptococcal pharyngitis (strep throat) Bacterial infection of throat Sore throat, swelling of pharyngeal  mucosa, fever, headache, nausea, abdominal pain Treat with antibiotics Scarlet fever Bacteria becomes systemic Characteristic “strawberry rash” Incubation 7 to 10 days Isolate 7 days32-32Infectious Diseases (cont.)Streptococcal pharyngitis(cont.)Rheumatic feverOccurs after apparent recovery from strep throatAutoimmune disorder – antibodies to streptococci cross-react with heart tissuesSymptoms – carditis, ECG changes, joint pain and inflammation, feverAcute post-streptococcal glomerulonephritisInflammation of glomerulus of the kidney resulting in inadequate filtering of the bloodSymptoms – swelling of hands and feet, decreased urine output, hypertension, protein in urine32-33Infectious Diseases (cont.)TetanusAcute infectious bacterial disease following a contaminated puncture wound Incubation – 3 to 21 daysLate symptoms – lockjaw, paralysisNo isolation needed, but reportable 32-34Infectious Diseases (cont.)Tuberculosis Infectious bacterial disease affecting mainly lungs Symptoms – night sweats, productive cough,  fever, chills, fatigue, unexplained weight loss, diminished appetite, bloody sputum Incidence – higher in urban centers Transmission Mycobacterium tuberculosis Droplet 32-35Infectious Diseases (cont.)Tuberculosis (cont.) Increasing resistance to TB Early diagnosis, prompt treatment Compliance with treatment regimen Preventing TB Vaccination – BCG (not used in the U.S.) Causes false-positive with TB skin test 32-36Infectious Diseases (cont.)Tuberculosis (cont.) Treating TB Mantoux TB test Positive test = Induration – skin turns red and becomes raised and hard Positive result from immunization or exposure to TB bacteria Treatment based on area affected and type of TB involved Patients must complete entire course of  treatment – 12 to 18 months on medication Isolation 32-37Preventing the Spread of TBContainment of the tuberculosis bacteriaPatient measuresCovering mouthProper disposal of tissuesTake medication as directedAvoid close contact with othersAir out their room Office measuresUse negative pressure areaUse personal respiratorApply standard sanitization, disinfection, and sterilization techniques32-38Apply Your KnowledgeANSWER: The spread of many infectious diseases can be limited or prevented by using commonsense precautions: Using tissues when coughing or sneezing Washing hands frequently Using disposable dishwareHow can the spread of many infectious diseases can be limited or prevented?Excellent! 32-39Drug-Resistant MicroorganismsMRSA – methicillin/oxacillin-resistant S. aureusVRE – vancomycin-resistant enterococciVISA – vancomycin-intermediate S. aureusVRSA – vancomycin-resistant S. aureusESBLS – extended-spectrum beta-lactamasesPRSP – penicillin-resistant Streptococcus pneumoniae32-40Drug-Resistant Microorganisms (cont.)MRSA and VREMost common in non-hospital health-care facilitiesCommunity-associated MRSAIncreasing in incidencePRSPCommon in patients seeking care in physicians’ offices and clinics (pediatrics)32-41Drug-Resistant Microorganisms (cont.)Risk factors for development of infections by drug-resistant organismsAdvanced ageInvasive proceduresPrior use of antibioticsRepeated contact with health-care systemSeverity of illnessUnderlying diseases or conditions32-42Preventing Antibiotic ResistanceFour strategies to reduce incidence of antibiotic-resistant microorganismsPrevent infectionDiagnose and treat infection appropriatelyUse antibiotics carefullyPrevent transmission of infections32-43Apply Your KnowledgeWhat strategies reduce the incidence of antibiotic-resistant microorganisms?ANSWER: Strategies to reduce the incidence of antibiotic-resistant microorganisms include: Prevent infections Diagnose and treat infections appropriately Use antibiotics carefully Prevent transmissionGood Job!32-44Disease ProcessBegins with microorganisms finding hostGrows with specific requirementsProper temperaturepH Moisture levelVirulence – microorganism’s disease-producing powerDamage is caused by:Depleting nutrientsReproducing themselvesMaking body cells the target of body’s own defensesProducing toxins32-45Disease Process (cont.)Once exposed to a pathogen, the body goes through 4 stages of illness:Incubation – begins at first exposure; ends when first symptom appearsProdromal – begins at first onset of symptoms; generally shortInvasion – numbers of organisms are greatest; symptoms are most pronouncedConvalescent – patient regains normal health status 32-46Apply Your KnowledgeANSWER: The four stages of illness are: Incubation – begins at first exposure; ends when first symptom appears Prodromal – begins at first onset of symptoms; generally short Invasion – numbers of organisms are greatest; symptoms are most pronounced Convalescent – patient regains normal health status What are the four stages of illness?SUPER!32-47The Body’s DefensesImmunity – condition of being resistant to pathogens and the disease they causeFirst lines of defenseSkin Sweat glandsMucous membranesCilia Lacrimal glandsSalivaHydrochloric acidLysozyme 32-48The Body’s Defenses (cont.)Resident normal flora – microorganisms found in the bodyProvide a barrier against pathogensNormally live in balanceBecome pathogenic when host’s defenses are compromisedOpportunistic infections Infections occurring when a host’s resistance is low32-49Nonspecific DefensesInflammation SignsRednessLocalized heatSwellingPain PurposeSummon immunologic agents to siteBegin tissue repairDestroy invading microorganisms 32-50Nonspecific Defenses (cont.)Steps of inflammationInitial constriction, then dilation of blood vessels, causing redness and heatFluid leakage from local vessels  swellingScar tissue formationChronic inflammation Damage to tissuesLoss of function32-51Nonspecific Defenses (cont.)PhagocytosisWhite blood cells (phagocytes) engulf and digest pathogens Three typesNeutrophils – found in pusMonocytes – formed in bone marrow and become Macrophages when they migrate to specific tissuesFound in lymph nodes, liver, spleen, lungs, bone marrow, and connective tissueDeliver antigens (foreign substances) to lymphocytes32-52Humoral ImmunityLymphocytes – B cells and T cellsT cells activate B cells to produce antibodies to neutralize an antigenMemory B cells respond quickly to produce antibodies in later invasionsSpecific antibodies are produced in response to specific antigensAntibodies attract phagocytes, which destroy antigens32-53Humoral Immunity (cont.)Types of immunityActive – body produces own antibodiesNatural activeArtificial active Passive – antibodies that are produced outside body enter the bodyNatural passiveArtificial passiveComplementProteins activated by antibodiesHelps white blood cells destroy pathogens32-54Cell-Mediated ImmunityT cells attack invading pathogen directly Helper T cells ActivateKiller T cells Bind with antigen and kill itSuppressor T cells Slow down or stop attack after antigen is destroyedMemory T cellsRespond quickly to another attack by same antigen32-55Apply Your KnowledgeWhat is the difference between active and passive immunity?ANSWER: Active immunity is long-term immunity in which the body produces its own antibodies.Passive immunity results when antibodies produced outside the body enter the body.Both can be natural or artificial.Impressive!32-56Cycle of InfectionA reservoir host – animal, insect, or human body capable of sustaining pathogen growthCarrier – unaware of presence of pathogenSubclinical case – unnoticeable infectionEndogenous infection – normally harmless microorganisms become pathogenicExogenous infection – pathogen introduced into the bodyClick for Cycle of Infection32-57Cycle of Infection (cont.)Means of exit – how the pathogen leaves the hostNose, mouth, eyes, or earsFeces or urineSemen, vaginal fluid, or other reproductive dischargeBlood or blood productsClick for Cycle of Infection32-58Cycle of Infection (cont.)Means of transmission – how a pathogen spreads to a hostAirborneBlood-borne During pregnancy or birthFoodborneVector-borneLiving organism that carries microorganisms to another personTouchingDirect Indirect through fomitesInanimate reservoir of pathogensDrinking glass, door knob, etc. Click for Cycle of Infection32-59Cycle of Infection (cont.)Means of entranceEnter through any cavity lined with mucous membraneMouth, nose, vagina, rectumEars, eyes, intestinal tract, urinary tract, reproductive tract, breaks in the skinClick for Cycle of Infection32-60Cycle of Infection (cont.)Pathogen factors Number and concentration Virulence Point of entry Susceptible host Individual with little or no immunity to infection by a pathogenHost factors influencing susceptibility AgeGenetic predispositionNutritional statusOther disease processesStress levelsHygiene habitsGeneral healthClick for Cycle of Infection32-61Cycle of Infection (cont.)Back32-62Cycle of Infection (cont.)Environmental factorsDense populationsAnimals – unpasteurized milkInsectsEconomic and political factorsAvailability of transportationPopulation growth ratesSexual behavior32-63Breaking the CycleAsepsis – condition in which pathogens are absent or controlledMaintain strict housekeeping standardsAdhere to government guidelines to protect against disease Educate patients in hygiene, health promotion, and disease prevention 32-64Apply Your KnowledgeANSWER: Fomites are inanimate objects such as clothing, water, and food that serve as a means of transportation for microorganisms.What are fomites?Nice Job!32-65In Summary32.1 Infection control has been a problem throughout history. Though there have been many advances, controlling infection continues to be a challenge for doctors.32.2 There is great variety in the types of pathogenic organisms. Types of potentially infectious microorganisms include prions, viruses, bacteria, protozoans, fungi, and helminths.32-66In Summary (cont.)32.3 It is important to be familiar with the diseases that infect people so that you can protect your patients, coworkers, and yourself. These diseases include but are not limited to chickenpox, croup, diphtheria, hepatitis, influenza, measles, mumps, and polio.32.4 Antibiotic resistance of microbial pathogens is a growing problem. The number of infections for which there is little or no treatment is increasing. It is the responsibility of health-care workers to use antibiotics wisely. 32-67In Summary (cont.)32.5 The CDC began a campaign to prevent antimicrobial resistance. There are four strategies outlined in the campaign: 1) prevent infection; 2) diagnose and treat infection appropriately; 3) use antibiotics carefully; and 4) prevent transmission of infections.32.6 There are numerous human pathogens. These pathogens cause disease by damaging the body in a number of ways including depleting nutrients needed by cells, reproducing themselves within body cells, making body cells the targets of the body’s own defenses, and producing toxins that damage cells and tissues.32-68In Summary (cont.)32.7 The body is able to protect itself from disease through the use of several lines of defense. These lines of defense may be nonspecific or specific.32.8 In order for an infection to occur, five elements must be in place. There must be a reservoir host, a means of exit, a means of transmission, a means of entrance, and a susceptible host.32.9 Direct disease transmission occurs when the pathogen moves immediately from one host to another. Indirect transmission is possible only if the pathogen is able to survive outside the host for some period of time.32-69In today's world, new infections and diseases can spread across the country and even across the world in a matter of days, or even hours, making early detection critical. ~ John LinderMember of the U.S. House of Representatives, GeorgiaEnd of Chapter 32