Specimen Cultures

Obtaining a culture

Practicum in Health Science

Culture specimens

A sample of microorganisms or tissue cells taken from an area of the body for examination.

Obtaining a culture

• Specimens (a sample for medical testing)

• Obtained from a variety of sites, including lesions on the skin or from the eyes, ears, nose, throat, or other body openings.

Open Ended

Have you ever had a culture taken from any part of you body? If yes, explain what was happening & what your health care providers checking for.

Culture Medium

• The medium provides nourishment for the cultured organism and keeps it moist so that it can be examined.

• Specimen must not be allowed to be in contact with any other substances or objects once obtained.

Sterile Collections

• Can be obtained & transported in a variety of STERILE collection containers

• Sterile: free of microorganisms

• Prevents cross-contamination

Open Ended

Why do you think it is important for specimens to be in a sterile container?

Direct smear

• A culture specimen placed on a slide for microscopic examination.

• The swab containing the specimen is applied on the slide . The smear is air dried or heat fixed, or passed through a flame, so the organisms will stick to the slide.

• After the direct smear is stained so that organisms are visible, it is examined, and the organism causing the disease is identified.

Open Ended

Once the lab creates, a direct smear, how would they view the slide to identify the microorganism?

Agar Plates

• The specimen can be placed or streaked on an agar plate, aka culture plate or petri dish, or into a culture media tube.

• Agar: solid medium that nourishes and moisturizes the organism. Needs incubation for 24–36 hours, and the organism is grown.

• Culturing an organism. A small sample (called a colony) is placed on a slide, stained, and then examined for identification.

• Exact identification sometimes requires growing a sample of the (the colony) on another special medium, helps to differentiate the microorganisms.

• Organism can be isolated at this point

Culture and sensitivity (C&S)

• small, sterile disks containing different antibiotics that are placed on plate after the organism added

• If grow to edge of a disk, the organism is resistant. The antibiotic would not work against the organism and would not help cure the disease.

• If do not grow close to disk, the organisms are sensitive. Antibiotic would work against the organism and aid in the curing of the disease.

• Dr's use to treat diseases

Multiple Choice

Is antibiotic sensitivity test used for treatment of disease?

• Yes

• No

Gram Stain

• Technique of staining organisms to identify specific types of bacteria present.

• Used to identify shape & arrangement of microorganisms

Open Ended

Can you name a gram negative & a gram positive bacteria?

Wrapping up

• Cultures may contain pathogenic organisms or be contaminated with blood and body fluids, standard precautions must be practiced!

• Use PPE- gloves, lab coat, eye protection

• Wash hands frequently

• Dispose of cultures properly

Open Ended

After learning all of this, can you explain why it is important to properly obtain specimen cultures and safely handle these microorganisms?