Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc. Assisting in Microbiology and...

Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc.

Assisting in Microbiology and Immunology

Chapter 54

Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc. Slide 2

Microbiology

The medical assistant needs to understand the role of microorganisms.

The main objective of microbiology procedures is to identify the organisms responsible for illness so that the physician can properly treat the patient.

Microbiology procedures may be performed in the POL or in the microbiology department of a medical referral laboratory.


Specimen Collection and Transport

“In what ways can I prevent extraneous microorganisms from contaminating this sample?”

“What can I do to prevent myself from becoming infected while I collect this sample?”


Specimen Collection and Transport

Transport media– Stuart medium or Amies medium

The medical assistant must strictly follow the directions.

Transport specimen directly after collection or by courier.


Containers for Transport


Collection Devices


Classification of Microorganisms

Bacteria, fungi, protozoa

Parasitic worms

Viruses


Naming of Microorganisms

Binomial system of nomenclature– Assigns two names: the first is the genus, and the

second is the species

– Neisseria gonorrhoeae


Typical Pathogenic Bacteria

Bacteria are single-celled prokaryote organisms that reproduce by binary fission.

Often classified by their shape, staining characteristics, and the environmental conditions.

Three types of cell wall structures: gram positive, gram negative, acid fast.


Bacterial Shapes


Bacterial Oxygen Requirements

Aerobes

Anaerobes

Facultative anaerobes


Bacterial Physical Structures

Flagella

Capsules

Endospores


Unusual Pathogenic Bacteria

Chlamydia

Mycoplasmic

Rickettsiae


Fungi

Mycology

Fungi are eukaryotes, larger than bacteria

Present in soil, air, and water

Few cause disease

Transmission


Parasites

Parasitology

Transmitted by ingestion during the infective stage, direct penetration of the skin, inoculation by a vector

Identified in urine, sputum, or tissue fluid or through tissue biopsy

Helminths

Protozoa


Parasites


The Microbiology Laboratory

Most laboratories have:

– Refrigerator, autoclave, safety cabinet, microscope, and incubator


Inoculating Equipment

Inoculating loops and needles


Incineration Equipment

Fastest way to sterilize reusable equipment

Used to heat-fix smears

Bunsen burner


Incineration Equipment (cont’d)


Culture Media

Solid, liquid, or semisolid


Inoculation of Media

Quadrant streak

Lawn or spread streak

After inoculation, plate is inverted


Identification of Pathogens in the Microbiology Laboratory

Assessing a culture– Throat culture

– Urine culture

Staining– Gram’s stain

– Acid-fast stain


Identification of Pathogens in the Microbiology Laboratory (cont’d)



Gram stain



Biochemical testing– Performed to identify the

genus and species

Rapid identification methods– Designed to give the physician a positive indication of

the problem

– Rapid strep testing

– Influenza A and B testing

– RSV testing


Identification of Pathogens in the Microbiology Laboratory (cont’d)


Antimicrobial Susceptibility Testing

“Culture and sensitivity” test.

The physician’s decision for antimicrobial agents is based on numerous factors.– Test results, physical examination, and the knowledge

of the patient

Kirby-Bauer Antimicrobial Susceptibility Test.


Antimicrobial Susceptibility Testing (cont’d)


Miscellaneous Microbiology Testing

Testing for pinworms– Specimens best collected at night or early before bowel

movement, urination, or bathing.

– Petroleum jelly paraffin swabs used to collect eggs.

– Parent may also be instructed to bring child to office.


Immunology Testing

Provides information about past or present infections with bacteria or viruses and certain cancers

Demonstrates the reaction between antigen and antibody– Agglutination, precipitation, immunochromatographic

assay


Immunology Testing

The medical assistant may perform CLIA-waived tests for infectious mononucleosis, H. pylori, HIV, and Lyme disease.


Patient Education

List of teaching topics to help educate patients– An explanation of patient’s type of infection

– How infection spreads

– Normal barriers to infection

– Risk factor

– Patient preparations, collection

– Hand washing, proper storage and cleaning

Copyright © 2007 by Saunders, Inc., an imprint of Elsevier Inc. Assisting in Microbiology and...

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