Chapter 15 - Introduction to microbiology. The objectives of this chapter are: Define microbiology; describe how microorganisms cause disease; describe how microorganisms are classified and named; explain how viruses, bacteria, protozoans, fungi, and parasites differ and give examples of each;...
CHAPTER 15 Introduction to Microbiology © 2011 The McGraw-Hill Companies, Inc All rights reserved 152 Learning Outcomes 15.1 Define microbiology 15.2 Describe how microorganisms cause disease 15.3 Describe how microorganisms are classified and named 15.4 Explain how viruses, bacteria, protozoans, fungi, and parasites differ and give examples of each © 2011 The McGraw-Hill Companies, Inc All rights reserved 153 Learning Outcomes (cont.) 15.5 Describe the process involved in diagnosing an infection 15.6 List general guidelines for obtaining specimens 15.7 Describe how throat culture, urine, sputum, wound, and stool specimens are obtained 15.8 Explain how to transport specimens to outside laboratories © 2011 The McGraw-Hill Companies, Inc All rights reserved 154 Learning Outcomes (cont.) 15.9 Describe two techniques used in the direct examination of culture specimens 15.10Explain how to prepare and examine stained specimens 15.11Describe how to culture specimens in the medical office © 2011 The McGraw-Hill Companies, Inc All rights reserved 155 Learning Outcomes (cont.) 15.12Explain how cultures are interpreted 15.13Describe how to perform an antimicrobial sensitivity determination 15.14Explain how to implement quality control measures in the microbiology laboratory © 2011 The McGraw-Hill Companies, Inc All rights reserved 156 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 157 • Microbiology – study of microorganisms (simple forms of life visible only with a microscope) Microorganisms Normal flora Pathogenic â 2011 The McGraw-Hill Companies, Inc All rights reserved Microbiology and the Role of the Medical Assistant (cont.) 158 • 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 159 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 1510 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 1545 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 1546 Culturing Specimens (cont.) • Incubating culture plates – 35 to 37º 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 1547 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 1548 Apply Your Knowledge 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 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 1549 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 1550 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 â 2011 The McGraw-Hill Companies, Inc All rights reserved 1551 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 1552 In Summary 15.1 Microbiology is the study of microorganisms, which are simple life forms that are microscopic and are commonly made up of a single cell 15.2 Microorganisms can cause disease by using up nutrients or other materials needed by the cells and tissues they invade, damaging body cells, and producing toxins 15.3 Microorganisms 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 1553 In Summary (cont.) 15.4 Viruses, bacteria, protozoans, fungi, and parasites differ in the following ways: viruses are among the smallest known infectious agents; bacteria are singlecelled 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 15.5 The 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 1554 In Summary (cont.) 15.6 The 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 15.7 Throat 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 1555 In Summary (cont.) 15.8 When 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 15.9 Direct examination of culture specimens is accomplished in two ways: wet mounts and KOH mounts © 2011 The McGraw-Hill Companies, Inc All rights reserved 1556 In Summary (cont.) 15.10 To 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 15.11 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 1557 In Summary (cont.) 15.12 The 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 15.13 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 1558 In Summary (cont.) 15.14 To 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 1559 End of Chapter 15 Each organism's environment, for the most part, consists of other organisms ~ Kevin Kelly © 2011 The McGraw-Hill Companies, Inc All rights reserved ... rights reserved 15 16 Viruses (cont.) • Illnesses caused by viruses – Colds – Influenza – Croup – Hepatitis – Warts – AIDS – Mumps – Rubella – Measles – Herpes • Vaccines are available for many viruses... reserved 15 10 How Microorganisms Cause Disease (cont.) • Localized symptoms – – – – Swelling Pain Warmth Redness • Generalized symptoms – – – – Fever Tiredness Aches Weakness • Normal flora – Provides... 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