Bài giảng Medical Assisting - Chapter 46: Introduction to Microbiology

Objectives: 46-1 Define microbiology. 46-2 Describe how microorganisms cause diseases. 46-3 Describe how microorganisms are classified and named. 46-4 Explain how viruses, bacteria, protozoans, fungi, and parasites differ and give examples of each. 46-5 Describe the process involved in diagnosing an infection.

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ChapterPowerPoint® to accompany Second EditionRamutkowski  Booth  Pugh  Thompson  WhickerCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.Medical Assisting Chapter 461Objectives:46-1 Define microbiology.46-2 Describe how microorganisms cause diseases.46-3 Describe how microorganisms are classified and named.46-4 Explain how viruses, bacteria, protozoans, fungi, and parasites differ and give examples of each.46-5 Describe the process involved in diagnosing an infection.Introduction to Microbiology 2Objectives (cont.)46-6 List general guidelines for obtaining specimens.46-7 Describe how throat cultures, urine, sputum, wound, and stool specimens are obtained.46-8 Explain how to transport specimens to outside laboratories.46-9 Describe two techniques used in the direct examination of cultures specimens.46-10 Explain how to prepare and examine stained specimens. Introduction to Microbiology3Objectives (cont.)46-11 Describe how to culture specimen in the medical office.46-12 Explain how cultures are interpreted.46-13 Describe how to perform an antimicrobial sensitivity determination.46-14 Explain how to implement quality control measures in the microbiology laboratory.Introduction to Microbiology4Introduction When microorganisms are pathogenic in nature or displaced from their natural environment, they cause infections and disease.You will learn:Processes in identifying microorganismsCulture medias usedAntimicrobial testingQuality control You must understand different life forms of microorganisms, how they may be identified, and how to teach proper collection techniques for common specimens.5Microbiology and the Role of the Medical Assistant Microbiology – study of microorganisms (simple forms of life visible only through a microscope usually single celled)Found everywhereCause infections Mild Severe6How Microorganisms Cause Disease By using up nutrients or other materials needed by cells and tissues they invadeBy damaging body cells by reproducing inside the cellsBy making body cells targets of body’s own defensesResulting in:FeverTirednessAchesWeaknessSkin reactionsGastrointestinal upset Transmitted from one person to another by direct touching or by vectors, droplets, or contaminated food or drink.7Classifications of Microorganisms Classifications:Subcellular – DNA or RNA surrounded by a protein coatProkaryotic – simple cell structure no nucleus or organellesEukaryotic – complex cell structure with nucleus and specialized organelles8Naming of Microorganisms Types of microorganisms:VirusesBacteriaProtozoansFungiMulticellular parasitesNamed by first word refers to genus (biologic classification between family and species) and second word refers to particular speciesStaphylococcus aureus9Viruses Smallest known infectious agentsCannot be seen by regular microscopeConsist of only nucleic acid surrounded by a protein coatCauses:ColdsInfluenzaCroupHepatitisHepatitis Virus10BacteriaSingle-celled prokaryotic organismsReproduce quickly Major cause of diseases Many different types and ways to identify themRapid reproduction is why untreated infections can be dangerousBacillus bacterial classification11Bacteria ClassificationShape – coccus, bacillus, spirillum, virbrioAbility to retain certain dyes Ability to grow in presence or absence of airBiochemical reactionsSpirillum bacterial classification12ProtozoansSingle celled eukaryotic organisms – larger than bacteriaFound in soil and waterCause:MalariaAmebic dysenteryTrichomonus vaginalisProtozoan Trichomonus vaginalis13FungiAn eukaryotic organism – rigid cell wallGrow mainly as single-celled Reduce by budding YeastsMoldsCause superficial infectionsAthlete’s footRingwormThrushYeast a single-celled fungi14Parasites Organism that lives on or in another and uses that organism to provide nourishmentInfections caused by parasites are called infestationsWormsInsects -ticks15Apply Your KnowledgeHow is bacteria classified?Shape – coccus, bacillus, spirillum, virbrioAbility to retain certain dyes Ability to grow in presence or absence of airBiochemical reactions-Answer16Diagnosing Infections Step 1 – Examine the patients signs and symptomsStep 2 – Obtain SpecimensStep 3 – Examine the Specimens DirectlyStep 4 – Culture the SpecimenStep 5 – Determine the Culture’s Antibiotic SensitivityStep 6 – Treat the Patient as Ordered17Specimen CollectionIf specimen is collected incorrectly, the organism will not grow in culture and then cannot be identified.If a specimen contains contaminants that are identified as causing the infection, the patient may be treated incorrectly.18Specimen Collection DevicesSterile swabsAbsorbent material on the tipCollection and transporting systemsContains a polyester swab and a small thin-walled vial of medium in a plastic sleeve19Throat Culture SpecimensAvoid touching any structures in the mouthGet the specimen from the throat area onlyClinical medical assistants must know how to obtain a throat culture specimen correctly 20Other Specimens UrineObtain clean-catch midstream specimen to prevent contaminantsSputumInstruct patient to cough up mucus from the lungsWound Use a swabStool Use clean paper plate or waxed paper21Transporting SpecimensMany offices do not perform microbiologic testing.You may send culture specimens to outside labs.There are three main objectives.22Transporting Specimens (cont.)Three main objectives:Follow proper collection procedures and use correct device.Maintain the samples in a state close to their original as possible.Protect anyone who handles the specimen container from exposure to potentially infectious material.23Methods of Transportation Regularly scheduled daily pickups by the labAs needed pickup by the labThrough the mail24Direct Examination of SpecimensPhysician may examine specimens under the microscope to detect microorganisms.Two types of procedures:Wet mounts- permits quick identification Potassium Hydroxide (KOH) mounts – suspects a fungal infection of the skin, nails, or hair.25Stained SpecimensEnables the doctor to differentiate between types of infections.The medical assistant should be able to prepare a specimen slide and perform a Gram’s stain.26Culturing SpecimensYou will need on-the-job training or additional courses to culture certain specimens.More common to send these specimens to outside labs. Culturing involves placing a sample of specimen on a culture medium.27Culturing Specimens (cont.)Culture media – liquid, semisolid, or solid formsMedium called – agarSpecial culture units – used to perform rapid urine cultures (Unicult)28Culturing Specimens (cont.)Inoculating a culture plateTransferring some of the specimen onto the plateLabel the plate:Patient’s nameDoctor’s nameSource of sampleDate and time of inoculationYour initials29Culturing Specimens (cont.)Streak the plate with the specimen swab for:Qualitative analysis – type of pathogen Quantitative analysis – number of pathogen present in the specimenIncubating Culture plates – to allow bacteria to grow (incubator set at 35 to 370 C)Allow to grow for 24 to 48 hours.30Interpreting CulturesThis step is performed by physicians, microbiologists, or technicians who have been properly trained.They will look for:Characteristics of colony growthRelative number of colony growthChanges in the media surrounding the colonies31Determining Antimicrobial SensitivityTaking a sample of the isolated pathogen and suspending it in a liquid medium and streaking it on a culture plate.Small disks of filter paper with antimicrobial agents are placed on top.Plate is incubated at 370 C for 24 hours.The antimicrobial that inhibited microbial growth will be effective in treating the infection.32Quality Control in the OfficeOngoing system to evaluate the quality of medical care being provided.Provides an objective means to define, monitor, and correct potential problems.All media, staining solutions, and reagents should be evaluated frequently.Equipment must also be in proper running order.33Impact of CLIA’ 88All labs must incorporate the appropriate policies and procedures to comply with CLIA’ 88Proper documentation of lab policies and procedures, materials, and lab personnel qualification and training.Proficiency testing program monitors quality of laboratory’s test results34Apply Your KnowledgeHow are pathogens tested to see if they can be treated effectively by antimicrobial agents? Small disks of filter paper with antimicrobial agents are placed on top of the inoculated culture plate, and if the antimicrobial agents stop the growth of the pathogens, it will be effective in treatment of the infection.-Answer35Summary Medical Assistant Developing your clinical skills will be an asset to the office and will allow you to advance your career. Quality control in the microbiology laboratory is an important factor in ensuring high-quality medical care.36End of ChapterEnd of Chapter 37
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