Module 1: Ch 1-2

Which type of host–microorganism relationship benefits the microorganism while causing harm to the host?

Mutualism

Symbiosis

Commensalism

Parasitism

Parasitism

• Two organisms live harmoniously together.

• Neither is detrimental

• Both organisms benefit (mutualism)

symbiosis

One organism benefits but the other does not and no harmful effects…

commensalism

A physician suspects a bacterial infection and submits a specimen to the microbiology laboratory. What is the primary responsibility of the clinical microbiology laboratory in this situation?

Identify the causative organism and provide susceptibility data

Prescribe the most effective antimicrobial therapy

Confirm the patient's immune status

Eliminate all microorganisms from the specimen

Identify the causative organism and provide susceptibility data

The ability of a microbe to produce disease in a susceptible host…

pathogenicity

Which microorganism is classified as a prokaryote and lacks a membrane-bound nucleus?

Virus

Yeast

Parasite

Bacteria

Bacteria

Which route provides a common portal of entry for microorganisms that bypass the body’s first line of defense?

Intact skin

Mucous membranes

Normal gastrointestinal flora

cuts, bites, or abrasions

cuts, bites, or abrasions

A Gram stain reveals organisms with an outer membrane containing endotoxin. Which cell wall component is responsible for this finding?

capsule

Peptidoglycan 

Lipopolysaccharide

Teichoic acid

Lipopolysaccharide

A bacterial isolate is resistant to phagocytosis by host immune cells. Which structure most likely contributes to this virulence factor?

Cell membrane

Capsule

Ribosomes

Flagella

Capsule

Which bacterial structure primarily contributes to motility and assists organisms in reaching favorable environments?

Flagella

Cell wall

capsule

Ribosome

Flagella

 Transfers DNA aids in mobility & reproduction…

pili or fimbriae

Large structured layer outside bacteria cell wall: cannot be washed off easily + causes various diseases

o Acts as a protective layer factor (virulence factor)

o Prevents destruction by white cells (prevents phagocytosis)

capsule

A laboratory report lists the organism Escherichia coli. Which portion of the name represents the genus?

Escherichia

E. coli

coli

The italicized portion only

Escherichia

What bacteria has a thin inner peptidoglycan layer, stains pink/red from safranin?

gram negative bacteria

A patient receiving chemotherapy develops an infection caused by organisms normally present on the skin. This situation best demonstrates which concept?

Normal flora becoming an opportunistic pathogen

Primary pathogenicity

Symbiosis

mutualism

Normal flora becoming an opportunistic pathogen

Which process is defined as the complete elimination of all microorganisms, including spores?

Disinfection

Decontamination

Antisepsis

Sterilization

Sterilization

• Thin peptidoglycan layer

• Contains an outer lipopolysaccharide layer

• Components include: Endotoxin (toxic portion), Core polysaccharide and Lipid A, O antigen

• Stains pink color (gram staining)

gram-negative (cell wall)

The Process of killing infectious organisms and rendering them inert. May be limited to a define scope of organims

Disinfection

Safranin is the most critical part of the staining process? True or False.

False

Which bacteria has the thicker peptidoglycan layer?

Gram positive

Transport media is used to help preserve the integrity of the sample? True or False.

True

• Thick peptidoglycan layer

• Contains teichoic acid and lipoteichoic acids

• Stains purple color

gram-positive (cell wall)

Why do we rinse between each reagent being added in the gram stain procedure?

Help the bacteria to stay on the slide

To wash away extra reagent

Activate the reagent

To check your water pressure

To wash away extra reagent

All of these samples should be considered sterile except?

CSF

Deep Tissue

Upper Respiratory

Bone

Upper Respiratory

A capsule is seen as a virulence factor because it helps bacteria escape phagocytosis? True or False.

True

Which of the host-microbe relationship has harmful effects on the host?

Parasitism

Symbiosis

Mutualism

Commensalism

Parasitism

Chocolate agar has Hemin and NAD factors. True or False.

True

What term is used to describe more than 1 rod shaped bacterium?

bacilli

What does this term mean Coccus

1 round bacterium

1 rod-shaped bacterium

More than 1 round bacterium

More than 1 rod-shaped bacterium

More than 1 round bacterium

When streaking a urine, you use isolation to achieve individual colonies. True or False.

False

Differential media is used for all of the following except?

Microbe characteristics

Enriched

Can be inhibitory
Aids in identification

Enriched

What is used to achieve the pink color staining pattern of Gram negative bacteria?

Safranin

What is used to achieve the purple coloring of grandpa positive bacteria?

Crystal Violet

What is the order of chemical use in a gram stain?

1. Crystal violet; primary stain

2. Mordant (iodine)

3. Decolorizer (alcohol/acetone)

4. Safranin; counter stain

Within a BAP and Choc agar, directly related to iron containing substances, Hemin…

X factor

Within a CHOC agar, heat must be applied to release the factor from the RBCs, contains NAD and coenzyme used in the metabolic process of Hemophilus species of bacteria….

V factor