question

which of the following are include in the study of medical microbiology

answer

study of immunology, the body's response to infectious agents. study of microbes that impact human health. study of approaches used in the prevention of infectious disease. development and use of methods for detection of infectious disease.

question

which of the following is a characteristic of members of the resident microbiota

answer

resident microbiota can compete with a limit growth of harmful bacteria

question

which of the following body sites normally have large numbers of resident microbiota

answer

nose, throat, vagina, large intestine, skin

question

a microorganism that is most often harmless but may occasionally cause infection and disease if the host defenses are compromised is referred to as an ___ pathogen

answer

opportunistic

question

which of the following are genera of gram-positive cocci frequently found as resident microbiota in humans

answer

staphylococcus, enterococcus, streptococcus

question

impetigo, a type of inflammatory skin infection, is caused by ___

answer

staphylococcus aureus, streptococcus pyogenes

question

the field of study in which medicine and microbiology intersect is known as ___ ___

answer

medical microbiology

question

the microorganisms that live in and on our body, generally without causing harm, are known as ___ ___

answer

normal flora

question

the specific microorganisms that make up the resident microbiota are generally the same at all body sites

answer

false

question

in which body sites are gram positive cocci predominant members of the resident microbiota

answer

nose, mouth and throat, skin

question

which of the following types of media might be particularly helpful in the isolation of a bacterial species from a mixed bacterial culture

answer

differential, selective

question

which of the following is the quickest way to isolate bacteria from a mixed culture

answer

streak plating

question

a specific example of a medium that can be used to isolate organisms from the human body because it is enriched with compounds that support the growth of fastidious organisms is ___ agar

answer

blood

question

which of the following is an example of a morphological characteristic that could be used in the bacterial identification process

answer

cell shape

question

match the following morphological characteristics with the correct genus

answer

streptococcus = gram positive cocci in chains staphylococcus = gram positive cocci in clusters diplococcus = gram positive in pairs

question

multiple bacterial species can have similar staining reactions and microscopic morphology

answer

true

question

the most reliable source of information regarding the tests that can be used to identify a particular bacterial isolate and the expected results is ___ manual

answer

Bergey's

question

when choosing a biochemical test to run on an unknown, you should consider which of the following

answer

choose an easy, rapid test that is standard for its main group of bacteria

question

a ___ key is a flowchart that can be used to identify an organism by making a series of choices until you arrive at one possibility

answer

dichotomous

question

before attempting to identify an unknown bacterial species, the organism must be isolated in a ___ culture

answer

pure

question

which of the following methods could be used to isolate bacteria from a mixed culture

answer

loop dilution pour plating. streak plating. serial dilution followed by spread plating.

question

how do you determine the species of an unknown bacterium

answer

you use standard tests and pre-existing knowledge to classify the bacterium

question

when choosing a biochemical test to run on an unknown, you should consider which of the following

answer

choose an easy, rapid test that is standard for its main group of bacteria

question

according to this flowchart, what test is most useful for distinguishing between streptococcus pyogenes and streptococcus pneumoniae

answer

hemolysis on blood agar

question

you have isolated a bacterial strain from a patient sample. in order to determine the identity of the bacterium, you have performed the following test

answer

streptococcus pneumoniae

question

the same tests are used on streptococci and staphylococci to determine the exact species identity of an unknown gram-positive coccus

answer

false

question

an unknown bacterium was streaked on the top half of a blood agar plate and a bacitracin disc was placed on it. a vertical streak with the unknown bacterium was made, along with an intersecting horizontal streak with S. aureus. after 24 hours, your plate looked like this

answer

bacitracin resistant / CAMP positive

question

twelve hours after adding a sample of bacteria to rabbit serum, your tube looks like this. are the unknown bacteria positive or negative for coagulase activity

answer

negative

question

is this bacterial isolate positive or negative for catalase activity

answer

negative

question

is this bacterial strain positive or negative for mannitol fermentation

answer

negative

question

you streak your unknown bacterium onto a blood agar plate and place a novobiocin disc onto the surface of the plate. after 24 hours, your plate looks like this. is the unknown bacterium sensitive or resistant to novobiocin

answer

resistant

question

you streak your unknown bacterium onto a blood agar plate and place an optochin disc on the surface of the plate. after 24 hours, your plate looks like this. is the unknown bacterium sensitive or resistant to optochin

answer

resistant

question

you evaluate a bile esculin agar slant 24 hours after you inoculated it with your unknown bacterium. is the bacterium positive or negative for esculin hydrolysis

answer

negative

question

the ___ test provides immediate results, based on the presence or absence of bubbling when hydrogen peroxide is dropped onto either a colony or onto a smear of the bacteria on a slide

answer

catalase

question

which biochemical test require small discs to be placed on the surface of a bacterial culture plate before incubation

answer

bacitracin susceptibility. novobiocin susceptibility. optochin susceptibility.

question

which biochemical test can readily differentiate staphylococcus from streptococcus

answer

catalase test

question

match each microorganism in the list below with an identifying biochemical test or feature

answer

staphylococcus aureus = coagulase positive streptococcus pyogenes = beta hemolytic, bacitracin sensitive streptococcus pneumoniae = alpha hemolytic optochin sensitive staphylococcus saprophyticus = novobiocin resistant enterococcus faecalis = bile esculin hydrolysis positive streptococcus agalactiae = beta hemolytic, CAMP test positive

question

identify items in this list that are characteristic of the genus streptococcus

answer

hemolytic activity on blood agar is helpful in differentiation. gram-positive. cocci in pairs or chains. catalase negative.

question

identify items in this list which are characteristic of all members of the genus staphylococcus

answer

ability to grow in 6.5% NaCl. gram positive cocci. catalase positive. cells are arranged in irregular clusters.

question

what biochemical test is most useful in differentiating staphylococcus species from streptococcus species

answer

catalase test

question

match each ingredient in mannitol salt agar with its role in the medium

answer

7.5% NaCl = inhibits bacteria other than staphylococci mannitol = fermentable carbohydrate phenol red = pH indicator

question

the complete clearing or hemolysis that a bacterial isolate may produce on blood agar is called ___ hemolysis, while partial hemolysis which produces a greenish discoloration referred to as ___ hemolysis

answer

beta; alpha

question

which biochemical test makes use of rabbit plasma as a reagent

answer

coagulase test

question

bile esculin medium is made selective by the incorporation of ___ , and differential by the incorporation of ___ and ferric citrate

answer

bile; esculin

question

which of the three test conducted in this identification process did not require the use of an incubator

answer

catalase test

question

based on this flowchart, what is true about staphylococcus saprophyticus

answer

possesses catalase enzyme. does not possess coagulase enzyme. may not ferment mannitol.

question

what would this organism look like under the microscope

answer

purple spherical bacteria in clusters

question

what test eliminated streptococci as potential agents in this case

answer

catalase test

question

based on the result recorded for the mannitol salt agar plate, what color was the medium after incubation

answer

pink

question

match each of the lab activities with their purpose

answer

culture = uses several different types of media to grow bacteria from patient specimens. identification = uses a variety of tests and media to determine the genus and species of a bacterial isolate. sensitivity = tests a microorganism with a battery of different antibiotics to determine which antibodies are most likely to control or eliminate the infection

question

close observation of the growth on blood agar revealed that the colonies were beta-hemolytic based on this observation alone, which two organisms in the list below are the most likely agents

answer

streptococcus pyogenes. staphylococcus aureus

question

the catalase test was negative. what two test might be done next

answer

bacitracin susceptibility CAMP test

question

which test will enable you to determine if these colonies are staphylococci or streptococci

answer

catalase test

question

which of the following correctly describes streptococcus agalactiae (group B strep)

answer

beta-hemolytic. synergistic hemolysis with S. aureus on blood agar. no zone around bacitracin disk appears in test on blood agar

question

match

answer

*staphylococcus saprophyticus = urinary tract infection in young women *streptococcus pyogenes = scarlet fever; strep throat *streptococcus agalactiae = sepsis and meningitis in newborn babies *streptococcus pneumoniae = conjunctivitis; meningitis in young children

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