Chapter 45 Assisting in Microbiology and Immunology Mod 1

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Cocci in packets of 4

Infectious Mononucleosis Testing

Commonly called Mono, is an acute infectious disease caused by the Epstein-Barr virus (EBV). EBV is one of the many herpes viruses. The virus is especially common in teenagers.

Healthcare-associated infections (HAIs)

Infections that patients acquire while receiving treatment for other conditions within a healthcare setting (e.g., ambulatory care, long-term care, or rehabilitation facility).

Before collecting specimens for microbiologic testing, you should ask yourself two questions:

1. How can I prevent contamination of this sample? 2. How can I protect myself from pathogen exposure while I collect this sample?

Clostridium difficile (C. diff)

A bacterium that can cause symptoms that range from diarrhea to severe inflammation of the colon (can be fatal). This condition is most commonly seen after antibiotic use.

Extract

A certain substance that is taken out of a group or solution and is in a concentrated form.

Antimicrobial

A general term used to describe drugs, chemicals, or other substances that can destroy or inhibit the growth of microorganisms. Can be antibiotics or antiviral, antifungal, and antiparasitic drugs or agents (e.g., there are chemical antimicrobial additives in hand soap).

Capsid

A genetic core covered by a protein coat

Mold:

A growth of tiny fungi forming on a substance. Often looks downy or furry and is associated with dampness or decay.

Transport medium:

A medium used to keep an organism alive during transport to the laboratory.

Binomial:

A name consisting of a generic and a specific term.

Extraction

A process by which a specific substance is separated from a group or solution.

Antibiotic

A substance or medication that can destroy or inhibit the growth of bacteria.

Nomenclature

A system of names or terms, used in science and art to categorize items.

Viable

Able to live and grow.

Nasal wash

Also called a nasal aspirate. A syringe is used to gently squirt a small amount of sterile saline into the nose, and the resulting fluid is collected into a cup (for a wash). Or after the saline is squirted into the nose, gentle suction is applied (for the aspirate).

heterophile antibody

An antibody that has an affinity for an antigen other than the specific antigen that stimulated its production.

Endospore

An inactive form of certain bacteria that can withstand poor environmental conditions. When conditions improve, the bacteria become functional again.

Light microscope

An instrument that uses focused light and lenses to magnify a specimen, usually a cell.

Broad-spectrum antibiotics:

Antibiotics that act against a wide range of disease-causing bacteria. Act against both Gram-positive and Gram-negative bacteria.

Arthropod

Any animal that lacks a spine, such as insects, crustaceans, arachnids, and others.

Microorganisms

Any living organism—such as bacterium, protozoan, fungus, parasite, or helminth—of microscopic size. Some definitions include viruses, which are not alive. Most microorganisms are good. Without microorganisms, we could not survive.

Fungus

Any of a diverse group of single-celled organisms, including mushrooms, molds, mildew, smuts, rusts, and yeasts and classified in the kingdom Fungi.

Prokaryote

Any organism that is made up of at least one cell and has genetic material that is not enclosed in a nucleus. Bacteria are prokaryotes, primitive organisms.

Eukaryote

Any single-celled or multicellular organism that has genetic material contained in a distinct membrane-bound nucleus.

Binary fission:

Asexual reproduction in single-celled organisms during which one cell divides into two daughter cells.

Binomial system

Assigns two names; the first name is the genus (plural, genera) and the second name is the species. Both names are either italicized or underlined when written. Swedish botanist Carl Linnaeus developed the binomial system of nomenclature to name all living organisms: animals, plants, fungi, protozoa, and bacteria.

Anaerobes

Bacteria that die in the presence of oxygen.

Yeast:

Belongs to various single-celled fungi, which reproduce by budding and are able to ferment sugars.

Saprophytes

Beneficial microorganisms that are responsible for breaking down organic matter. They help break down plants and organic waste in farming, water purification, composting, and gardening.

Disinfectants:

Chemical agents used on nonliving objects to destroy or inhibit the growth of harmful organisms.

Unusual Pathogenic Bacteria

Chlamydia, Mycoplasma, and Rickettsia are tiny, unusual bacteria that fall between the size ranges of typical pathogenic bacteria and viruses. Chlamydia are tiny bacteria that require host cells for growth. They once were considered viruses. Rickettsia are tiny Gram-negative bacteria that are transmitted by blood-sucking insects. Rickettsia cannot multiply outside a living host cell. Mycoplasmas are unusual in that they have no PG in their cell wall.

Acid-fast cells

Contain a thin layer of PG surrounded by a thick layer of waxlike lipids. Acid-fast bacteria do not stain well with a Gram stain, but they stain pink with the acid-fast stain

Asexually

Describes reproduction that does not involve the fusion of male and female sex cells, such as in plant reproduction, fission, or budding.

Antiseptics

Describes substances that inhibit the growth of microorganisms on living tissue (e.g., alcohol and povidone-iodine [Betadine]); they are used to cleanse the skin, wounds, and so on.

Nasopharyngeal

Describes the part of the throat behind and above the soft palate and connected to the nasal passages.

Pneumonia

Inflammation of the lungs with congestion of the air sacs (alveoli). Can be caused by a bacterium or virus.

Bronchiolitis

Occurs when the small airways of the lungs become inflamed because of a viral infection.

Pathogenic Parasites

Parasites are transmitted by ingestion, direct penetration of the skin, and injection by an arthropod. A parasite cannot be identified accurately based on a single test or specimen. Parasites are frequently identified in feces, blood, urine, sputum, tissue fluid, or tissue biopsy samples.

Parasitic

Pertaining to a parasite. (An organism that lives on or in another organism, known as the host. Benefits from the host; the host does not benefit from the parasite.)

Serologic:

Pertaining to the science involving the immune properties and actions of serum.

Pathogenic Fungi

Present in the soil, air, and water, but only a few species cause disease. They are transmitted by the following: • Direct contact with infected persons • Prolonged exposure to a moist environment • Inhalation of contaminated dust or soil

Antibodies

Protein substances produced in the blood or tissues in response to a specific antigen; they destroy or weaken the antigen. Part of the immune system.

Pathogenic Protozoa

Protozoa are single-celled parasitic organisms that contain a nucleus. They range in size from microscopic to macroscopic (visible to the naked eye) (Table 45.6). They are present in moist environments and in bodies of water, such as lakes and ponds. Protozoa are transmitted through contaminated feces, food, and drink.

Viral:

Relating to or caused by a virus.

Sensitivity testing

Reported to the provider in one of three categories for each antibiotic tested: • S means that the pathogen is susceptible, or that the antibiotic is effective in destroying that particular organism. • R means that the pathogen is resistant, or that the antibiotic is not effective in destroying that particular organism. • I means intermediate, or that additional testing must be performed to determine the dosage of antibiotic necessary for successful treatment.

Bacteria:

Some of a large group of microorganisms that are single-celled, lack a nucleus, reproduce asexually, or can form spores. Some can cause disease. The most abundant life form on earth.

Streaking for Isolation

Streaking for isolation is also called a four-quadrant streak. It is a procedure that is performed with most microbiology specimens. By distributing bacteria across the agar plate and isolating bacterial colonies, laboratory personnel can see characteristics of the bacteria that are useful in the identification process.

Tinea

Superficial fungal infection "ringworm" . Most tinea skin infections start out as a little dot on the skin that grows bigger in an ever-expanding circle. It looks like the pathogen is creating a large swirl on the skin. That is why it is called ringworm.

Gram Stain

The Gram stain, developed by Dr. Hans Christian Gram in the late 1800s, is still the most commonly used stain in microbiology. This procedure involves applying a sequence of reagents: a primary stain, mordant, decolorizer, and counterstain to the slide. Bacteria react best in the Gram stain when they are less than 24 hours old.

Choosing an Appropriate Antibiotic Agent

The appropriate antibiotic agent meets the following criteria: • Destroys the infectious agent with a reasonable level of the drug • Is the least toxic to the patient • Has the least impact on normal flora of the body • Has the desired pharmacologic (fahr muh KOL loh jik) characteristics (preparation, route of delivery, effectiveness) • Is the most economical

CLIA-Waived Microbiology Testing

The first step in performing these tests is to review the package insert provided by the manufacturer. This gives the following valuable information about the test: • Principle on which the test is based • Reagents and equipment needed • Proper specimen collection techniques • Patient preparation requirements • Test procedures • Any precautions or warnings pertaining to the procedure The insert also provides information about quality control, interpretation of results, limitations of the procedure, and references.

Titer

The lowest concentration of a serum solution containing a specific antibody where the antibody is still able to neutralize (or precipitate) an antigen.

Lyme Disease Testing

The most common insect-borne infectious disease in North America, and it is a significant public health concern. The disease is contracted from an infected tick that bites a person. The bacteria are in the saliva of the tick. These ticks typically are found on deer, mice, dogs, horses, and birds.

Acute stage:

The phase during which rapid multiplication of the pathogen takes place. Symptoms are very distinct. A strong response of the immune system takes place during this stage.

When bacteria are found in pairs

The prefix diplo- is used

When they are found in grapelike clusters,

The prefix staphylo- is used

When bacteria are in a chain formation

The prefix strepto- is used.

Molecule:

The simplest unit of a chemical compound that can exist, consisting of two or more atoms held together with chemical bonds.

Parasitology

The study of all parasitic organisms that live on or in the human body.

Immunology

The study of the immune system

lateral flow immunoassay

This means that the specimen "flows" into the test area.

Enterobius vermicularis

commonly known as pinworm. This species of parasite primarily infects the colon of young children. Humans are infected by ingesting mature eggs through the following: • Hand-to-mouth transfers • Feces-contaminated fingers • Feces-contaminated foods or liquids • By inhaling eggs in air currents from infected areas

RSV

spiratory syncytial virus Antiviral agents are available to treat RSV infection, rapid diagnosis can lead to the following: • Shorter hospital stays • Reduced need for antibiotic therapy to treat secondary bacterial infection • Lower cost for hospital care The tests are intended for children under age 5.

If patients do not follow the directions

there is a real chance of the following: • Developing complications • Having a relapse of an infection • Allowing an infection to spread to other areas or becoming systemic

Methicillin-Resistant Staphylococcus aureus:

(MRSA) A Gram-positive pathogen that is resistant to multiple antibiotics.

Normal flora:

Microorganisms (mostly bacteria and yeast) that live on or in the body. Normal microscopic residents of the body.

To prevent sample contamination, do the following:

• Wash hands properly, and wear gloves. • Cleanse the area to be sampled with an antiseptic, if possible. • Open sterile containers only when necessary. • Never touch a sterile swab or collection device to a nonsterile surface.

Helminths

Are parasites called worms. Helminths live on or in another living organism. They sustain themselves at the expense of the host organism. They can live in animals or humans. Worms are usually transmitted through the soil, by infected clothing or fingernails, contact with infected persons, or contaminated food/water. Helminths go through the same life cycle as other worms.

Pathogens

Disease-causing organisms or agents.

Specimen Collection and Transport in the Physician Office Laboratory

Results are only as good as the quality of the sample. Specimens for microbiology testing must be collected carefully so that contaminating microorganisms are not introduced into the specimen.

Bacterial Shapes

Round bacteria are called cocci. • Rod-shaped bacteria are called bacilli. • Spiral-shaped bacteria are called spirilla . Tightly coiled spirilla are called spirochetes

Protozoa

Single-celled organisms that are the most primitive form of animal life. Most are microscopic. Examples are amoebas, ciliates, flagellates and sporozoans.

Equipment and supplies in a microbiology laboratory

Vary with the size of the facility. Most laboratories have a refrigerator, an autoclave, a safety cabinet, a microscope, and an incubator.

Fixing a Slide

Either heat or methanol can be used to fix the sample to the slide. Fixing results in the material (sample) adhering to the slide. Both heat (e.g., from a Bunsen burner or an incinerator) and methanol cause protein in the sample to break down and stick to the slide. It is similar to how an egg would stick to a hot frying pan.

Staining

Gram stain differentiates bacteria into two categories according to chemical makeup of the cell wall. The acid-fast stain differentiates bacteria into two categories based on the presence or absence of a waxy lipid in the cell wall.

Gram-positive cells

Gram-positive bacteria stain purple

Bacterial Staining Properties

Gram-positive, Gram-negative, and acid-fast structures.

CLIA-Waived Immunology Testing

Immunology testing provides information about past or present infections with bacteria or viruses. It also detects certain types of cancers. Testing done in the immunology department is designed to demonstrate the reaction between an antigen and its specific antibody.

Infectious agents

Living and nonliving pathogens—such as bacteria, viruses, fungi, protozoa, parasite, helminths, and prions—that can cause disease. Also called infectious particles.

Aerobes

Bacteria that require oxygen to live.

Mycology

The study of fungi and the diseases they cause.

sarcinae

Cocci in packets of 8 or 16

Gram-negative cells

Gram-negative bacteria stain pink or red

Facultative anaerobes

Can survive in the presence of oxygen but prefer to live without oxygen.

Mycoplasma pneumonia

Referred to as "walking pneumonia."

-gen

Substance that produces

Convalescent stage

The phase during which the host recovers gradually and returns to baseline or normal health.

Educate a patient about infection control:

• An explanation of the patient's type of infection: bacterial, viral, fungal, or parasitic • How infections spread • Hand washing and sanitization, proper storage and cleaning of personal items, and disposal of contaminated supplies • Risk factors for infection, such as poor nutritional habits or poor ventilation with airborne pathogens present • The patient's role in specimen collection • Patient preparation for laboratory tests, imaging tests, and other needed procedures

The normal flora in and on our bodies is needed for the following processes:

• Digesting food and making nutrients available to the body. • Forming blood clots. Vitamin K is used in the clotting process and is made by bacteria (bak TEER ee uh) in our intestines. • Preventing pathogens from invading our skin, mucous membranes, and gastrointestinal and genitourinary tracts.

Many types of samples are collected. Some examples are as follows:

• Sterile swabs can be used to collect samples from wounds and the upper respiratory tract. • Serum or whole blood can be used to test for infectious organisms. • Urine samples are normally collected at the POL. • Fecal samples can be collected by the patient at the POL or at home.

To protect yourself from pathogen exposure, do the following:

• Use proper hand washing techniques. • Wear gloves, a fluid-impermeable lab coat, a surgical mask (for droplet or airborne pathogens), protective eyewear, or a face shield. • Always wear gloves when handling any patient specimen, even if you are not going to be testing the sample at that time.

Infection control procedures

• Using proper hand hygiene • Wearing appropriate personal protective equipment (PPE) • Observing recommended precautions for infectious agent transmission • Using appropriate antiseptics and disinfectants • Performing sterilization procedures