Humans are surrounded by tiny living organisms invisible to the naked eye. For the most part, these microorganisms cause no problems; however, when they are pathogenic in nature or are displaced from their natural environment, they can cause infections and disease. This chapter ad-dresses the different life forms of microorganisms and how they may be identified; it also teaches you the proper collection technique for common types of specimens. You will learn about the processes involved in identifying microorganisms, the types of culture media used for these processes, how antimicrobial testing is done, and how quality control fits into ensuring reliable patient results.

Outline

• Microbiology and the Role of the Medical Assistant
• How Microorganisms Cause Disease
• Classification and Naming of Microorganisms
• Viruses
• Bacteria
• Protozoans
• Fungi
• Multicellular Parasites
• How Infections Are Diagnosed
• Specimen Collection
• Transporting Specimens to an Outside Laboratory
• Direct Examination of Specimens
• Preparation and Examination of Stained Specimens
• Culturing Specimens in the Medical Office
• Determining Antimicrobial Sensitivity
• Quality Control in the Medical Office

Learning Outcomes

After completing Chapter 46, you will be able to:

 46.1 Define microbiology.
 46.2 Describe how microorganisms cause disease.
 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.
 46.6 List general guidelines for obtaining specimens.
 46.7 Describe how throat culture, 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 culture specimens.
 46.10 Explain how to prepare and examine stained specimens.
 46.11 Describe how to culture specimens 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.

Summary

A variety of microorganisms can cause infection. They are a major cause of disease in humans. As a medical assistant, you play an important role in the diagnosis and treatment of infection.

Collecting a microbiologic specimen is the most important step in diagnosing an infection. To ensure accurate results, you must use the correct collection device and technique. Then you must process the specimen or trans-port it to the laboratory in a timely manner to enable recovery of microorganisms.

The process of identification often begins when the doctor examines the fresh or stained specimen. Most specimens are cultured and incubated, and the resultant growth is evaluated. The antibiotic sensitivity of an isolated pathogen can then be determined to aid the doctor in making treatment decisions.

Quality control in the microbiology laboratory is an important factor in ensuring high-quality medical care. The focus and attention you bring to this part of your work will pay handsome dividends in terms of patient care, lab-oratory safety, and personal satisfaction. Developing your clinical skills will be an asset to the office and will allow you to advance in your career.