microbiology midterm 1

All of the organisms we work with are pathogenic ?

False

All of the organisms we work with should be handled as if they are pathogenic ?

True

All of the organisms we work with should be handled as if they are opportunistic ?

True

Wash hands with disinfectant and wipe bench tops with soap and warm water before starting any lab exercise and after all work has been completed ?

False

The following are not allowed in the lab ?

All of the above

In the lab long hair should be tied back and loose clothing should be worn ?

False

Inoculation loops and needles are flamed before and after use ?

True

Aerosols created by splattering of cultures are caused by improper flaming and cooling of needles and loops before use ?

True

The mouth of test tubes and other culture vessels are to be flamed before use ?

True

Everything going into the incubator must be labeled with name, microbial content and other data, using black marking tools ?

True

Non-contaminated waste goes into the autoclavable bags. Contaminated disposable waste goes into the waste basket ?

False

Never lay tubed media down vertically, at anytime it will spill ?

False

Aseptic techniques are any techniques employed to encourage contamination ?

False

Methods to prevent contamination include?

All of the above

An axenic culture is a mixed culture of organism of interest ?

False

Typically growth media is sterilized by flaming ?

False

An autoclave sterilizes by using halogenated gases ?

False

Flame inoculating tools using the Bunsen burner until they are red hot in order to sterilize ?

True

Blow on the sterilized inoculating tools to cool them ?

False

Test tubes are fitted with loose caps that will not come off, so you can hold the tube by the cap?

False

Contents of tubes will spill if you lay the tube on the table or invert it ?

True

Hold the tube in your non-dominant hand (right handed people should hold the tube in their left hand) and the inoculating loop in your dominant hand?

True

When handling a petri dish with agar tilt the lid up to open it, do not completely remove it ?

True

Airborne microorganisms can contaminate sterile media and inoculating tools ?

True

Most bacterial cultures will be incubated at 55`c for 24 to 48 hours?

False

Define Colony ?

All of the above

Define Ubiquitous?

Present everywhere

Characteristics of a pure culture include?

None of the above

Cultural characteristics include size, form, margin, elevation, opacity, color?

True

One of the most important steps in identifying a new bacteria or one isolated from a patients specimen is noting colony morphology ?

True

Colony morphology is described as how the colony or clone of cells looks on the agar surface?

True

Colony morphology is identical between various microbial species?

False

Colony morphology does not vary with microbial growth conditions ?

False

Nutrients present in various media or incubation conditions may contribute to altered colony size or appearance ?

True

Increased or specific carbohydrate content may result in more pronounced bacterial capsule synthesis, leading to very mucoid colonies ?

True

Some temperatures may be restrictive or stimulating to growth of specific species ?

True

Mycobacterium, mycoplasma, chlamydia, and rickettsia are not pathogens ?

False

Species of rickettsia can cause pneumonia, urogenital and other infections and are normally found in normal mucous membrane microflora?

False

Mycobacterium, mycoplasma, chlamydia, and rickettsia are not classified as true bacteria ?

False

Mycobacterium, mycoplasma, chlamydia, and rickettsia are extremely large and cannot be cultured by ordinary methods ?

False

Mycoplasma are pleomorphic because they have no cell wall?

True

Mycoplasmas can be opportunistic pathogens ?

True

Mycoplasmas can pass through sterilizing filters, and do not stain with ordinary stains ?

True

Mycoplasmas are susceptible to the antibiotics which act by inhibiting cell wall synthesis?

False

A type of colony morphology form includes ?

Filamentous

A type of colony morphology margin includes ?

Filamentous

Types of colony morphology elevation include ?

All of the above

Rickettsia are very small bacteria that can only grow and multiply intracellular, as they are obligate parasites ?

True

Rickettsia have a cell wall that cannot be stained?

False

Rickettsia must be grown in cell culture or intact animals ?

True

Most rickettsia are transmitted by arthropods like bats ?

False

Pathogenic rickettsia include the causative agents for typhus and rocky mountain spotted fever ?

True

Chlamydia are motile, coccoid, obligate intracellular parasites ?

False

Chlamydia have three life forms, or stages, known as the elementary body, primary body and the reticulate body ?

False

Chlamydia must grow and multiply inside another cell; then they are released to infect new cells ?

True

There are two species of Chlamydia responsible for human disease: psittaci (parrot fever) and trachomatis (STD, trachoma, LGV) ?

True

Psittaci and trachomatis can only be studied in cultured cells or intact animals ?

True

Microbial colonies can be colored/pigmented because of loss of nutrients and carbohydrates to the growth media ?

False

If the organisms produces an extracellular pigment the media turns colorless ?

False

Both the media and the colonies may be colored if the bacteria produces an intracellular pigment and an extracellular pigment ?

True

The are different degrees of opacity ?

True

In colony morphology, "size" relates to the size of the bacterial cell ?

False

To examine size, observe colonies in the most densely populated quadrant of the plate (e.g., first quadrant) ?

False

Size distinctions to be made include pinpoint, small, medium, and large ?

True

In colony morphology, "margin" refers to what the edge of the colony looks like ?

True

To observe elevation, it is best to look at the bottom of your plate ?

False

To observe elevation, it is best to look at the top of your plate ?

False

In colony morphology, "transparency" is how much light is able to pass through the colony ?

False

To observe opacity, hold the plate obliquely to the overhead light or place the plate over the writing of your textbook/ notebook handout ?

True

Transparent colonies allow all of the light to pass through them ?

True

Translucent colonies allow most of the light to pass through them; some light is blocked ?

True

Opaque colonies block none of the light ?

False

If the bacteria produce an intracellular pigment that is retained by the cell, the colony becomes colored ?

True

If the bacteria produce an extracellular pigment that is excreted by the cell, the medium becomes colored ?

True

If the organisms are translucent, the colored media will show through the colonies, and the colonies will appear to have the same color as the media ?

True

White colonies or translucent colonies that take on the color of the straw colored media are termed "pigmented" ?

False

characteristics surface or internal components that are of value in identifying organisms include:

All of the above

Special stains are available for characteristics surface or internal components as well as for other cell components to aid in the study of microbes ?

True

The acid-fast stain is a differential stain for mycobacterium and related bacteria

True

Mycobacterium is a genus that includes the causative ages of leprosy and tuberculosis ?

True

It is useful clinically to have a stain for rapid identification of mycobacterium in sputum or skin scrapings ?

True

Mycobacterium are unusual in that the cell wall has a mixture of waxy lipids called mycolic acids, that prevent the bacterium from staining by simple and gram stains ?

True

In the acid- fast stain, a green stain (carbolfuchsin) is cooked into the waxy cell wall, and cannot be removed with acidified alcohol ?

False

Fatty lipids called mycolic acids also prevent drying of the microbe ?

False

A stain that is cooked into the waxy cell wall, and cannot be removed with acidified alcohol is acid fast ?

True

Non acid fast bacterium and tissue background will lose the carbolfuchsin stain when washed with acid fast alcohol, becoming colorless?

True

A counterstain (methylene blue) is used to see them non acid fast bacterium ?

True

The genus mycobacterium contains some pathogens and many saprophytic species, found in soil and water, and also on human skin and mucous membranes ?

True

Mycobacterium grows very fast in the laboratory on a complex media ?

False

Often it will take 9 weeks for visible growth of mycobacterium in culture ?

False

Acid- fast stain is important for quick diagnosis because some strains of mycobacterium, such as M. leprae, cannot yet be grown in culture?

True

Capsules are found on some bacteria (and fungi)

True

Capsules may actually relate to pathogenicity in some strains, such as streptococcus pneumoniae, klebsiella pneumoniae, and clostridium perfringens ?

True

Small capsules can protect the microbe from host defense mechanisms, especially phagocytosis?

False

Capsules are often identified immunologically, but can also be visualized with a simple gram stain

False

In a negative stain technique, material such as India ink or Congo red is used to coat the slide but not penetrate the cell or capsule

True

A stain can be used to color the cells, and then the capsule is seen as a clear region surrounding the cells against the dark background

True

There are direct and indirect methods of staining capsules

True

Flagella are tiny hairlike organelles for pathogenicity ?

False

Flagella have a carbohydrate structure requiring a special staining technique

False