Micro 10-11

Which technique(s) is/are used to help identify and classify bacteria?

-Culture characteristics

-Nucleic acid analysis

-Microscopic examination

-Biochemical tests

All of the choices are correct.

If an acid-fast bacterium is detected in a clinical sample, then the organism could be

Mycobacterium leprae

Phage typing

is used to distinguish bacterial strains

DNA probes have been very useful in

identifying organisms in pure culture.

In 1908 Orla-Jensen suggested that bacteria be grouped according to their

physiology

Strains of an organism can always reliably be identified using RFLPs (restriction fragment length polymorphisms).

false

If the GC content of two organisms is 60%, the

organisms are most likely related.

Sequencing of rRNA is useful for

determining evolutionary relationships AND identification of unknown bacteria.

The "breath test" for Helicobacter pylori infection detects the presence of which of the following?

Urease

Which type of ribosomal RNA is most often used in taxonomy?

165

In E. coli O157:H7, the O157:H7 refers to the

the specific LPS and flagella type present.

The more closely related two organisms are,

the more similar their nucleic acid sequence

You are sent three clinical samples and are asked to determine whether they are the same strain. You perform standard identification techniques but cannot come to a conclusion. You decide to do an RFLP test. You digest the genomes of the organisms with the same restriction enzyme and run a gel. Each organism yields 5 bands on the gel, of the following sizes:

Organism A: 3 kb, 7 kb, 11 kb; 14 kb, 21 kb; Organism B: 3 kb, 7 kb, 2 kb, 8 kb, 11 kb; Organism C: 11 kb, 3 kb, 14 kb, 7 kb; 21 kb

What conclusion(s) can you make from this result?

Organisms A and C are likely the same strain but are different from organism B.

A DNA similarity of 75% between two organisms

suggests the organisms are closely related at the species level

An early attempt by Cohn at bacterial classification grouped bacteria according to their

shape

If the GC content of two organisms is 45% in both,

they may or may not be related.

Streptococcus pyogenes would be

beta hemolytic AND catalase negative.

You are a lab technician processing a patient sample taken from a throat swab. You have performed a Gram stain and observed chains of purple spherical cells. A catalase test is positive. Colonies on blood agar are β-hemolytic. From these results you can conclude that

the sample does NOT contain Streptococcus pyogenes

Very often clinically relevant information may be obtained by examining

a wet mount AND the size and shape of the organism

Media that change color as a result of the biochemical activity of growing bacteria

usually contain a pH indicator.

You perform a series of tests on an unknown bacterium in an effort to identify it. The organism is a Gram-negative, catalase positive and coagulase positive coccus. Consider the dichotomous key and select the CORRECT statement.

COME BACK TO THIS!!!!!!!!

Which of the following describes a method used to test for the enzyme urease?

A biochemical test conducted in the laboratory using a medium that contains urea and a pH indicator.

Serratia marcescens colonies are red when incubated at 37°C.

False

All known species of bacteria are described in Bergey's Manual of Systematic Bacteriology.

True

Modern approaches to evolutionary taxonomy often involve

comparison of DNA or RNA

Complex structures called fruiting bodies are a characteristic of

myxobacteria

Swarmer cells are

formed by Myxobacteria

The most medically relevant species of Pseudomonas is P. aeruginosa.

True

Lactic acid bacteria such as Streptococcus are obligate fermenters that can exist in an aerobic environment due to their use of catalase to mitigate the presence of oxygen.

False

Oxygenic prototrophs are primary producers. What does this mean?

They convert CO2 into organic compounds, sustaining other forms of life.

Which of the following about Mycoplasma is FALSE?

They are killed by penicillin.

The purple sulfur and green sulfur bacteria

both use hydrogen sulfide as a source of electrons

Propionibacterium

produces propionic acid AND is responsible for the holes in Swiss cheese.

Many spirochetes are difficult to cultivate, so their classification is based on their

morphology AND ability to cause disease

The genomes of free-living spirochetes are larger than those living in animal hosts. Why might this be so?

Free-living spirochetes will need genes for additional proteins to synthesize or obtain their own food from the environment. Parasitic spirochetes obtain nutrients from the animal host.

Heterocysts

are found in nitrogen-fixing cyanobacteria AND are used to protect nitrogenase.

Bacteria and Archaea both have members that use sulfur compounds as a terminal electron acceptor.

True

Which causes uncontrolled growth of plant tissue, resulting in a tumor?

Agrobacterium

Which of the following microbes is(are) important to cheese-making?

Lactic acid bacteria AND Propionibacterium

Agrobacterium species

contain the Ti plasmid that modifies the growth of plant tissue

Which of the following is NOT a Gram-negative rod associated with gastrointestinal signs/symptoms?

Clostridioides difficile

Which of the following is/are obligate intracellular parasites?

Chlamydia and Rickettsia

Rhizobium is considered an endosymbiont with plants.

True

Chlamydia occurs in two forms, a reticulate body and an elementary body.

True

Please select the definition that is INCORRECT.

Mycobacteria—Gram-negative bacteria that group together to form complex fruiting bodies.

Which of the following are spirochetes?

Borrelia AND Treponema

Which of the following statements about members of the family Enterobacteriaceae is NOT true?

Members only reside in the intestinal tract of humans.

Which of the following genera are obligate intracellular parasites?

Chlamydia, Coxiella, AND Rickettsia

Organisms that typically produce colonies with a fried egg appearance are the

Mycoplasmas

Endospores

are a dormant form of a bacterium AND are formed by members of medically relevant groups of bacteria.

In a MALDI-TOF assay,

a microorganism's proteins are separated and sorted by mass to generate a profile that provides a fast way to identify a colony.

Horizontal DNA transfer may make it more difficult to construct phylogenetic trees.

True

A soluble greenish pigment is produced by

Pseudomonas aeruginosa

Why might it be easier to identify the bacterium that caused pneumonia than one that caused a wound infection?

Bacteria that cause pneumonia can be identified with few tests because the lungs have no normal microbiota. Many bacteria are normally found on the skin however; these may be in the wound, complicating identification.

Woese

was involved in determining rRNA sequences AND proposed breaking prokaryotes into two groups.

The name Lactococcus (Streptococcus) lactis

indicates that Streptococcus is the old genus name

The three domain classification scheme uses

Archaea, Bacteria, Eukarya.

Size and shape may allow one to differentiate between a bacterium, fungus, and protozoan.

True

Explain the difference between a biotype and a serotype.

A biotype is the biochemical profile of a particular microorganism, while the serotype is the difference in its surface structures/antigens that will lead to separate immune responses from an organism (characterized by presence of different antibodies in the individual's serum).

Please select the FALSE statement regarding taxonomic hierarchy.

A domain is a collection of similar kingdoms; there are three domains: Bacteria, Archaea, and Animalia.

rRNA sequence comparisons are useful for determining evolutionary relationships.

True

API^TM, Enterotube^TM , and Vitek^TM and are all

commercially available methods used to identify bacteria.

The basic taxonomic unit in the classification scheme of plants and animals is

species

Which technique(s) is/are used to help identify and classify bacteria?

-Microscopic examination

-Biochemical tests

-Nucleic acid analysis

-Culture characteristics

-All of the choices are correct

All of the choices are correct

Intracellular Gram-negative diplococci found in a urethral sample from a male is indicative of

Neisseria gonorrhoeae

A situation in which diagnostic tests used to identify pathogens are done at or near the site of patient care is called

point-of-care testing (POCT)

Phenotypically identical bacteria

may be told apart by DNA sequence analysis

Streptococcus pyogenes can be easily distinguished microscopically from other Streptococcus species.

False

The genus of bacteria that is able to fix nitrogen and form heterocysts is

anabaena

Phycobiliproteins are

found in cyanobacteria AND used to gather wavelengths of light that are not well absorbed by chlorophyll.

Which of the following is NOT associated with a Clostridium species?

Strep throat

The methanogens

are part of the domain Archaea AND oxidize hydrogen gas to produce methane

Pseudomonas species

are resistant to many disinfectants and antimicrobials AND are mostly harmless except for the opportunistic P. aeruginosa

The lactobacilli, in their role as normal microbiota of the vagina, help the vagina resist infection by contributing to

acidity of the vagina

Please select the FALSE statement regarding sheathed bacteria.

The sheath allows these bacteria to perform photosynthesis

How could heavily fertilized lawns contribute to cyanobacterial blooms in lakes and oceans?

Run-off from the lawns will get into the water system, leading to large amounts of nitrogen that can be used by cyanobacteria in water systems.

What distinguishes Staphylococcus, species from Streptococcus, Enterococcus and Lactococcus species?

The production of catalase

Archaea are typically found living in extreme environments. An exception to this are the

methanogens

Which of the following organisms is the causative agent of Hansen's disease (leprosy)?

Mycobacterium leprae

Azotobacter

fixes nitrogen.

How do bioluminescent bacteria aid the flashlight fish?

They help the fish confuse predators and capture prey.

Which statement comparing Rhizobia and Agrobacterium is TRUE?

Rhizobia are plant endosymbionts; Agrobacterium is a plant pathogen

How can Staphylococcus species be distinguished from other aerobic species including Streptococcus, Enterococcus, and Lactococcus species.

Staphylococci are catalase-positive

Streptomyces produce a number of antibiotics.

True

Which of the following structures would be the best choice as a biological indicator to test autoclave operations?

Endospores formed by Geobacillus stearothermophilus

What is the function of sheaths in aquatic bacteria?

-They help the bacteria attach to surfaces

-They protect the bacteria from predators

Anaerobic chemolithotrophs

obtain energy by reducing inorganic chemicals.

Which statement regarding the Gram stain is FALSE?

Gram staining can be used to differentiate intestinal normal microbiota from pathogens—for example differentiating E. coli from Salmonella enterica.

A breath test assaying for radioactive carbon dioxide may be used to indicate the presence of

Helicobacter pylori.

The point at which two organisms diverged from a common ancestor

can be determined by comparing the nucleic acid sequences

Disagreements between conclusions obtained from rRNA data and other techniques may be explained by

horizontal DNA transfer

Methanogens often grow in association with

fermentative bacteria.

Anoxygenic phototrophs grow photosynthetically only under aerobic conditions.

False

Thermus and Deinococcus

survive in extreme environments