CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 46 Introduction to Microbiology

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes 46.1Define microbiology. 46.2Describe how microorganisms cause disease. 46.3Describe how microorganisms are classified and named. 46.4Explain how viruses, bacteria, protozoans, fungi, and parasites differ and give examples of each.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes (cont.) 46.5Describe the process involved in diagnosing an infection. 46.6List general guidelines for obtaining specimens. 46.7Describe how throat culture, urine, sputum, wound, and stool specimens are obtained. 46.8Explain how to transport specimens to outside laboratories.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes (cont.) 46.9Describe two techniques used in the direct examination of culture specimens Explain how to prepare and examine stained specimens Describe how to culture specimens in the medical office.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes (cont.) 46.12Explain how cultures are interpreted Describe how to perform an antimicrobial sensitivity determination Explain how to implement quality control measures in the microbiology laboratory.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Introduction Microorganisms cause disease or infection –Pathogenic in nature –Displaced from their natural environment Medical assistant –Identification of microorganisms –Proper collection techniques –Testing procedures –Quality control

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Microbiology and the Role of the Medical Assistant Microbiology – study of microorganisms (simple forms of life visible only with a microscope) Microorganisms –Normal flora –Pathogenic

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Microbiology and the Role of the Medical Assistant (cont.) Medical assistant –Assists physician –Obtains specimens –Prepares specimens for direct examination –Prepares specimens for transportation to reference laboratory –If office has a POL, performs microbiologic procedures

© 2011 The McGraw-Hill Companies, Inc. All rights reserved How Microorganisms Cause Disease Cause disease in variety of ways –Use nutrients needed by cells and tissues –Damage cells directly –Produce toxins May remain localized or become systemic Transmission –Direct contact –Indirect contact

© 2011 The McGraw-Hill Companies, Inc. All rights reserved How Microorganisms Cause Disease (cont.) Localized symptoms –Swelling –Pain –Warmth –Redness Generalized symptoms –Fever –Tiredness –Aches –Weakness Normal flora –Provides a barrier –Can cause an infection

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge 1. What role does the medical assistant play in relation to microbiology? ANSWER: The medical assistant may assist the physician in obtaining specimens, obtain specimens herself, prepare specimens for direct examination or transport to a reference laboratory, and possibly perform microbiologic procedures. 2. How do microorganisms cause disease? ANSWER: Organisms cause disease by using nutrients needed by cells and tissues, damaging cells directly, or producing toxins.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Classification and Naming of Microorganisms Classification by structure –Subcellular – DNA or RNA surrounded by a protein coat – viruses –Prokaryotic – simple cell structure with no nucleus or organelles – bacteria –Eukaryotic – complex cell structure with nucleus and specialized organelles – protozoans, fungi, parasites

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Classification and Naming of Microorganisms (cont.) Standardized naming –Genus Category of biologic classification Example – Staphylococcus –Species of organism Represents a distinct type of microorganisms Examples – Staphylococcus aureus and Staphylococcus epidermidis

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Describe the classifications of microorganisms and give an example of each. ANSWER: Microorganisms are classified as: Subcellular organisms that have DNA or RNA surrounded by a protein coat – viruses Prokaryotic organisms have a simple cell structure with no nucleus or organelles – bacteria Eukaryotic have a complex cell structure with nucleus and specialized organelles – protozoans, fungi, parasites

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Viruses Smallest known infectious agents Subcellular microorganism –Have only nucleic acid surrounded by a protein coat –Must live and grow in living cells of other organisms Hepatitis Virus

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Viruses (cont.) Illnesses caused by viruses –Colds –Influenza –Croup –Hepatitis –Warts Vaccines are available for many viruses –AIDS –Mumps –Rubella –Measles –Herpes

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Bacteria Single-celled prokaryotic organisms Reproduce rapidly Classification –Shape –Ability to retain dyes –Ability to grow with/without air –Biochemical reactions Bacillus Bacterial Classification

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Bacterial Classification and Identification Shape –Coccus – spherical, round, or ovoid –Bacillus – rod-shaped –Spirillum – spiral-shaped –Vibrio – comma-shaped Spirillum Bacterial Classification

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Bacterial Classification and Identification (cont.) Ability to retain certain dyes –Gram’s stain –Acid-fast stain Ability to grow in presence or absence of air –Aerobes – grow best in the presence of oxygen –Anaerobes – grow best in the absence of oxygen Biochemical reactions

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Bacterial Classification and Identification (cont.) Special groups –Mycobacteria – bacilli with a cell wall that differs from most bacteria –Rickettsiae Very small Live and grow within other living organisms such as mites and ticks –Chlamydiae Cell wall structure differs from other bacteria Live and grow within other living cells –Mycoplasmas – completely lack the rigid cell wall

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Protozoans Single-celled eukaryotic organisms, larger than bacteria Found in soil and water Illnesses –Malaria –Amebic dysentery –Trichomoniasis vaginitis Leading cause of death in developing countries Protozoan Trichomonas vaginalis

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Fungi Eukaryotic organisms with rigid cell wall Yeasts –Single-celled –Reproduce by budding Molds –Large, fuzzy, multicelled organisms –Produce spores Superficial infections –Athlete’s foot –Ringworm –Thrush Can cause systemic infections Yeasts: single- celled fungi

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Multicellular Parasites Organisms that live on or in another organism and use it for nourishment Parasitic worms –Usually due to poor sanitation –Roundworms –Flatworms –Tapeworms Parasitic insects –Bite or burrow under the skin –Mosquitoes –Ticks –Lice –Mites

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Matching: ___ Yeast or moldA.Virus ___ Tapeworm/liceB.Bacteria ___ Classified by shapeC.Protozoan ___ Subcellular organismD.Fungus ___ May be aerobic or anaerobicE.Multicellular parasite ___ Smallest known organism ___ Found in soil and water E A B B C A Very Good! E B E A B E B A B E D A B A B E ANSWER: D

© 2011 The McGraw-Hill Companies, Inc. All rights reserved How Infections Are Diagnosed Steps to diagnosis and treatment 1.Examine the patient Presumptive diagnosis May or may not need additional tests 2.Obtain specimen(s) Label properly Include presumptive diagnosis

© 2011 The McGraw-Hill Companies, Inc. All rights reserved How Infections Are Diagnosed (cont.) 3.Examine specimen directly Wet mount Smear 4.Culture specimen Culture medium – contains nutrients Examine culture visually and microscopically

© 2011 The McGraw-Hill Companies, Inc. All rights reserved How Infections Are Diagnosed (cont.) 5.Determine sensitivity to antibiotics 6.Treat the patient as ordered Antimicrobial – to kill pathogen or suppress its growth

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge What is the process for diagnosing an infection? ANSWER: There are six steps for diagnosis and treatment of an infection: 1.Examine the patient4. Culture the specimen 2.Obtain specimen(s)5. Determine sensitivity 3.Examine specimen directly6. Treat patient/appropriate antimicrobial Super!

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Specimen Collection Must be collected correctly –If not, may not grow in culture –Contaminants may be mistakenly identified –Patient may receive incorrect or harmful therapy

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Specimen Collection (cont.) Devices –Use appropriate collection device or specimen container –Sterile swabs – absorbent material on the tip Collection and transporting systems –Sterile, self-contained –Transport medium –Aerobic or anaerobic

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Guidelines for Specimen Collection Avoid causing harm, discomfort, or undue embarrassment Collect from appropriate site Obtain specimen at correct time Use appropriate devices Obtain sufficient quantity of specimen Obtain specimen prior to the start of antimicrobial therapy Label correctly

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Specimen Collection (cont.) Throat culture specimens –Swab back of throat in the area of the tonsils –Avoid touching any structures in the mouth –Prepare culture plate or prepare correctly for transport to laboratory

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Specimen Collection (cont.) Urine specimen –Clean-catch midstream to minimize contaminants –Process within 60 minutes or refrigerate Sputum specimen –Specimen from lungs –Avoid contaminating specimen with saliva

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Specimen Collection (cont.) Wound specimen –Swab wound or lesion –Do not touch outside of wound Stool specimens –Technique varies Bacterial infection Protozoal or parasitic infection –Instruct patient in correct collection procedure

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge What are the general guidelines for specimen collection? ANSWER: They are to avoid causing harm, discomfort, or undue embarrassment; collect from appropriate site; obtain specimen at correct time; use appropriate collection devices; obtain sufficient quantity of specimen; obtain specimen prior to the start of antimicrobial therapy; and label specimen correctly.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Transporting Specimens to an Outside Laboratory Many offices send cultures to an outside lab Three main objectives –Follow proper collection procedures and use proper collection device –Prevent deterioration of specimen –Protect anyone handling specimen

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Transporting Specimens to an Outside Laboratory (cont.) Regularly scheduled daily pickups by the lab As-needed pickup by the lab Through the mail –Follow U.S. Public Health Service regulations –Etiologic Agent label

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge What are the objectives for transporting a specimen to an outside laboratory? ANSWER: They are to follow proper collection procedures and use the proper collection device, prevent deterioration of the specimen during transport, and protect anyone that will handle the specimen from exposure. Impressive!

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Direct Examination of Specimens Enables physician to initiate treatment immediately Wet mounts –NaCl mixed with specimen of glass slide –Presence of pathogen and movement of microorganism Potassium hydroxide (KOH) mounts –Used if a fungal infection of the skin, nails, or hair is suspected –KOH dissolves keratin that can mask presence of a fungus

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Preparation and Examination of Stained Specimens Quick, tentative diagnosis Differentiation between types of infections Gram’s stain –Moderate- complexity test –Bacteria either retain or lose purple color Gram-positive bacteria Gram-negative bacteria

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Culturing Specimens in the Medical Office More common to send specimens for culture to outside labs Culturing involves placing a sample of specimen on a culture medium –Medium – nutrients –Place in incubator for growth – colony develops as microorganism multiplies

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge 1. What are the methods for preparing a slide for direct examination by the physician? ANSWER: They are wet mount and KOH mount. 2. How does the examination of stained specimens facilitate patient care? ANSWER: Stained specimens enable the physician to provide a quick, tentative diagnosis and differentiate between types of infections.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge 3. What is the process for culturing a specimen? ANSWER: The culture medium is inoculated with the specimen and placed in an incubator to promote growth of the organism on the culture medium.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Culturing Specimens (cont.) Culture media –Liquid, semisolid, or solid forms –Contains agar –Selective or nonselective Special culture units –Rapid urine culture – Uricult –Also available for throat, vaginal, and blood specimens

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Culturing Specimens (cont.) Inoculating a culture plate –Transfer some of the specimen onto a culture plate –Label the plate correctly –Qualitative analysis – determination of type of pathogen –Quantitative analysis – number of bacteria present in sample

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Culturing Specimens (cont.) Incubating culture plates –35 to 37 º C for 24 to 78 hours –Agar side up Interpreting cultures –Requires skill and practice –Characteristics of colonies –Relative number –Changes to media around colonies

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Determining Antimicrobial Sensitivity An outside lab reports –Sensitive – no growth –Intermediate – little growth –Resistant – overgrown Procedure –Filter paper containing antimicrobial agents placed on inoculated agar plate –Incubated for 24 hours –Evaluate effectiveness of agent

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge 1. What is the difference between selective and nonselective culture media? ANSWER: Selective culture media allows the growth of only certain kinds of bacteria. Unselective culture media support the growth of most organisms. 2. The office received a culture sensitivity report on a bacteria that said it was resistant to an antimicrobial. What does this mean? ANSWER: It means that the bacteria was not killed by the antimicrobial and that there was an overgrowth of the bacteria.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Quality Control in the Medical Office Ongoing evaluation of the quality of medical care being provided Objective means to define, monitor, and correct potential problems  Routine evaluation  All media, staining solutions, and reagents  Equipment

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Quality Control: Impact of CLIA ’88 Appropriate policies and procedures Proper documentation –Lab policies and procedures –Materials –Personnel qualifications and training Participation in proficiency testing program

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge What is the purpose of a quality control program in the medical office? ANSWER: To provide an ongoing evaluation of the quality of medical care provided and to provide an objective means to define, monitor, and correct potential problems. Very Good!

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary 46.1Microbiology is the study of microorganisms, which are simple life forms that are microscopic and are commonly made up of a single cell. 46.2Microorganisms can cause disease by using up nutrients or other materials needed by the cells and tissues they invade, damaging body cells, and producing toxins. 46.3Microorganisms are classified on the basis of their structure and are named in a standard way, using the genus to which the microorganism belongs and the particular species of the organism.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 46.4Viruses, bacteria, protozoans, fungi, and parasites differ in the following ways: viruses are among the smallest known infectious agents; bacteria are single- celled prokaryotic organisms that reproduce very quickly; protozoans are single-celled eukaryotic organisms that are generally much larger than bacteria; and fungi are eukaryotic organisms that have a rigid cell wall. 46.5The steps involved in diagnosing an infection are to examine the patient, obtain specimens, examine the specimen, culture the specimen, and determine the culture’s antibiotic sensitivity.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 46.6The general guidelines for obtaining specimens are: obtain the specimen with care; collect the material from a site; obtain the specimen at the proper time; use appropriate collection devices; obtain a sufficient quantity of the specimen; and obtain the specimen before antimicrobial therapy begins. 46.7Throat culture, urine, sputum, wound, and stool specimens are obtained in very specific ways. It is important to follow office procedures when obtaining specimens for testing purposes.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 46.8When transporting specimens to outside laboratories, the medical assistant should follow proper collection techniques using specific containers provided by the laboratory, maintain the samples in a state as close to their original as possible, and protect anyone who handles a specimen container from exposure to potentially infectious material. 46.9Direct examination of culture specimens is accomplished in two ways: wet mounts and KOH mounts.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 46.10To prepare a stained specimen, the medical assistant must first prepare a smear, fix the sample to the slide so that it does not wash off during the staining process, and follow a specific staining procedure. The sample is then observed under a microscope for certain characteristics To culture a specimen, the medical assistant should place a sample of the specimen on or in a specialized culture medium and allow it to grow in an incubator for 24 to 48 hours.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 46.12The process of interpreting a culture involves noting the characteristics and relative numbers of the colonies growing on the agar as well as any changes in the media surrounding the colonies Performing an antimicrobial sensitivity test involves taking a sample of the isolated pathogen, suspending it in a small amount of liquid medium, and streaking it evenly on the surface of a culture plate. Small disks of filter paper containing various antimicrobial agents are placed on top of the inoculated agar plate and the plate is then incubated at 37°C, and the results are evaluated the following day.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 46.14To implement a quality control program in a microbiology laboratory, the medical assistant should develop an up-to-date procedures manual; monitor laboratory equipment; monitor media, supplies, and reagents; ensure that the laboratory personnel are qualified; and ensure adequate space.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Each organism's environment, for the most part, consists of other organisms. ~ Kevin Kelly End of Chapter 46