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Veterinary Bacteriology: Test 1 old exam questions
old exam questions
81
Microbiology
Professional
09/15/2011

Additional Microbiology Flashcards

 


 

Cards

Term
Using the nomenclature of the A-B model for binary toxin structure, the B subunit of anthrax toxin would most closely correspond to...
Definition

protective antigen

(edema factor and lethal factor would be A / active subunit)

 

Term
The principal polymer structure of a bacterial cell wall (peptidoglycan) acquires most of its strength at a final step in the synthesis that involves crosslinking through...
Definition

N glycosidic linkages

bind at penultimate AA and cleave it off to acheive strong bond

Term
Would the involvement of an integron as a mechanism of multidrug resistance be more likely in e coli (Gram -) or in s aureus (Gram +) ?
Definition

e coli


Term
True or false: In an individual animal, a positive test for antibodies against a pathogen is always indicative of an infection.
Definition

FALSE

infection could have already passed

Term
True or False: In an individual animal, disease is always a consequence of infection
Definition

FALSE

carriers, normal flora, etc

Term
Disease prevalence usually has the greatest impact on which property of testing?
Definition
Positive predictive value
Term
The Beta lactam ring found in all penicillin and cephalosporin antibiotics has the greatest structural homology with
Definition

 

Terminal alanine dipeptides in peptidoglycan (gram + peptidoglycan)

 

Term
When bacteria are actively growing, their numbers increase in what fashion?
Definition
logarithmically
Term
T/F: Prokaryotic and eukaryotic organisms can possess a cell wall
Definition

true

fungi are eukaryotes that have cell walls

Term
T/F Prokaryotic and eukaryotic organisms replicate by mitosis
Definition

FALSE

bacteria replicate by binary fission

Term
The conditions employed for destruction of endospores in an autoclave are..
Definition

121 C  for 15 minutes

high pressure is also used

heat is provided by steam (hot air would take much longer to sterilize)

Term
T/F Germination of bacterial endospores is dependent on an activating factor that ends the state of dormancy and may cause slight damage to the spore coat
Definition
TRUE
Term
Germination of bacterial endospores is dependent on an intiating factor that causes degradation of the ______ _____ and _____, ______ of ________ and release of _____ and _______ acid.
Definition
spore coat and cortex, absoption of water and release of calcium and dipicolinic acid
Term
Peptidoglycan is associated with Gram +, Gram -, or both?
Definition

BOTH

Gram + has more

Term
Teichoic acid is found in Gram
Definition
positive
Term
Gram + and - have plasmids that encode for _____ ______
Definition
antibiotic resistance
Term

What does NOT limit the commercial development of lytic bacterial viruses to combat bacterial infections in animals?

 

a)poor immunogenicity of bacterial viruses

 

b) host specificity of bacterial virus

 

c) potential trasnfer of bacterial genes from a pathogen to a non-pathogen

d) metaboilic activity of bacterial viruses

Definition
A
Term

 

The MIC (minimum inhibitory concentration) of an antimicrobial drug for a bacterium is usually expressed in which unit?

Definition
micrograms per milliliter
Term

The best choice of media for isolation of a fastidous bacterial pathogen is

Definition

chocolate agar

does not have chocolate!

blood that has bascially been cooked for the bacteria

not a selective medium

fastitidous = picky eater

 

Term

Bacteria with storage granules (cytoplasmic inclusions) will have a ______  with methylene blue or Gram's stain

Definition

beaded filament appearance

uneven staining

Term

____ developed his ideas about germ theory of disease by inoculating animals with ATTENUATED ORGANSISMS

Definition
Pasteur
Term

Specimen transport and storage: diagnostic specimens should be placed in ____ ______ for transport

Definition

two containers

(should be well sealed)

Term

The greatest weakness of antibody detection as a means of diagnosing bacterial disease is...

Definition

antibodies are indicative of antigen exposure

could be not disease or not current disease

Term

 

 

Feature of _______ that differentiates them from insertion sequences, is a possession of terminal invert repeat sequences:

 

a) transposons

 

b)integrons

c)both  

 

Definition
B
Term

 

Feature of _______ that differentiates them from insertion sequences, is the ability to readily move across some distance in a cell form one DNA molecule to another:

 

a)integrons

 

b)transposons

C)both 

 

Definition
B
Term

 

Feature of _______ that differentiates them from insertion sequences, is possession of a strong generic promoter sequence:

 

a)integrons

 

b)transposons

c) both

 

Definition
A
Term

 

 

 

Feature of _______ that differentiates them from insertion sequences, is association with antibiotic resistance:

a) integrons

 

b)transposons

c)both

 

 

Definition

 

C

Term

Trace metal that is required in greatest abundance for growth of bacteria is...

Definition
IRON
Term

Lingering bacterial inhibition in the body after antimicrobial drug levels disappear is....

Definition

Post-antibiotic effect

Term

 

               

Dependency on fermentation as a means of generating energy from carbohydrate substrates is greatest among...

Definition

 

Obligately anaerobic bacteria

 

Term

Methicillin resistance in Staphylococcus species is usually indicative of...

Definition

resistance to all beta lactams

mecA gene!

Term

Chronic and recurrent forms of canine pyoderma caused by Staphylococcus pseudintermedius are often complicated by...

Definition

hypersensitvity and immune complexes

skin barriers are weakened

Term

Fluid and electrolyte replacement is most critical to individual patient care during

Definition

 

diarrheal disease caused by enteric infections.

 

Term

Bacillus anthracis requires ________  for capsular production.

Definition

carbon dioxide

heat

Term

 

               

________ infections are acquired within hospitals

Definition
nosocomical
Term

The principal function of lysozyme in the mucosal lining of the GI tract is to ___________           

Definition

destroy bacterial cells

(breaks glycosidic bond in peptidoglycan)

Term

When an antibiotic drug molecule binds to the target macromolecule associate with its antibacterial action in a bacterial cell, the drug is _____________ and unavailable to bind to _________________________-.

Definition

irreversibly bound; other bacterial targets

(1st order rate kinetics)

Term

Severe intestinal disease that develops in some patients after administration of a broad-spectrum antibiotic is most likely the result of an _______________________________            

Definition

imbalance of the normal bacterial flora caused by the antibiotic

Term
T/F infectious disease is the same thing as communicable disease
Definition
FALSE
Term

When not causing disease, Streptococcus equi subspecies equi is likely to persist for the longest period of time in ___________________--

Definition

asymptomatic animal carriers.

guttural pouch?

Term

A positive predictive value is...  

Definition
the likelihood that a positive test result is a true positive
Term

A flagellar filament is composed of...

Definition

a polymer of a single protein subunit.

Term

Many strains of staphylococcus aureus express a plasminogen activator that causes dissolution of fibrin clots. This product is called

Definition

 staphylokinase

Term

 

 

The _____ (organ) is most active in removing bacteria from the blood stream

Definition
spleen
Term

The O antigens of Gram negative bacteria are protective against ___________.

Definition

 

complement mediated lysis

Term

_______________- is part of the repeated subunit structure of BOTH lipid A AND peptidoglycan.

Definition

N-acetyl glucosamine


Term

Two of the most important safety concepts that should be addressed when shipping or internally transporting infectious substances are:

Definition

secondary containment and external package hazard communication

Term

When selecting a drug to use, choose the one that has the zone of inhibition______________               

Definition

that is the largest

larger zone diameter is more likely to be susceptible

Term

Intuitively, one would expect that gram ______ bacteria are preferentially more susceptible than gram______ bacteria to drugs that inhibit membrane function.  

Definition

negative; positive

less osmotic stability in gram -

Term

Insertion of a________________- into a chromosomal bacterial toxin gene is most likely to result in toxin gene inactivation.

Definition
lysogenic bacteriophage
Term

Once initiated, bacterial endospore production usually requires

Definition
8-10 hours
Term

The process of creating a live, relatively harmless and usually stable form of a pathogenic bacterium is called?

Definition
attenuation
Term

In an iron-restricted environment, pathogenic Staphylococcus sp. Are able to grow faster than less pathogenic Staphylococcus sp. Due to their ability to up-regulate genes that encode?           

Definition

siderophores

this was multiple choice; another option not listed could be hemolysis and heme binding

Term

Side chain substitutions in members of a particular class of antimicrobial drugs are LEAST likely to affect….

Definition

Mode of action of drug on bacteria

Term

The role of agar in bacterial growth is best described as…

Definition

Non-nutritional support matrix

Term

A bacterium that has a high MIC for a particular drug… (Minimum Inhibitory Concentration)

Definition

Is likely to be refractory to usual treatments w/ the drug during infection

Term

A property of the stratum corneum that enhances the antimicrobial barrier functions of skin is…

Definition
antibacterial lipids
Term

C3b, the cleavage product of the third component of complement, is of central importance to the host, especially against invasive infections caused by capsulated bacteria because it…

Definition

Enhances phagocytosis in the absence of bacteria-specific antibodies


complement is able to act without recognzing a specific antigen (it is part of

innate immunity)

recognises PAMPs (pathogen associated molecular patterns)

Term

A chronic pyogranulomatous process involving subcutaneous tissues of the foot in birds is commonly associated w/ staphylococcus aureus infection. This condition is called…

Definition
bumblefoot
Term

Cellular stimulation through non-specific binding to T lymphocyte receptors and macrophage major histocompatibility complex proteins best describes the mode of action of…

Definition

Staphylocococal toxic shock syndrome toxin

Term

If an assay measures bacterial growth endpoints in broth as the change in visible opacity from clear to turbid, the highest (and most sensitive) final concentration of the starting bacterial inoculum that would be suitable is…

Definition

5x10^5 cfu/ml

Term

Global (transcriptional) regulation of many genes involved with staphylococcal disease is triggered by…

Definition

Staphylococcal population density

(Quorum sensing)

Term

The best empirical drug choice for treating a severe infection caused by methicillin resistant Staphylococcus aureus would be…

Definition

Vancomycin (a narrow spectrum, glycopeptide antibiotic)

same mechanism as beta lactams (cell wall synthesis) but not the same chemical structure

Term

Clavulanic acid is known primarily as a…

Definition

Beta lactamase inhibitor

administered along with drug

Term

It is often recommended that the duration of antimicrobial treatment for an acute infection should be…

Definition

 

Continued for 48 hours after disappearance of symptoms

 

Term

Acidic Polysaccharide polymers of glycerol or ribitol phosphate…

Definition

(teichoic acids)

Are major surface antigens of many Gram positive bacteria




Term

Myeloperoxidase is an enzyme that is useful in…

Definition

Oxygen dependent bacterial killing in phagolysosomes

other oxygen dependent enzymes: NADPH oxidase, superoxide dismutase

oxygen independent: pH, lysozyme, cationic proteins, lactoferrin, vitamin B12 binding protein, acid hydrolases

Term

Integrons are most frequently associated w/…

Definition
antibacterial resistance
Term

As commonly performed, the color of gram-positive bacteria in a Gram stain smear is

Definition

PURPLE

crystal violet stain

gram negative is pink/red: safranin

Term

Alcohol based handwashing solutions should be used…

Definition

BEFORE EATING

not for endospores, they will resist

it's not a replacement for sterile gloves

don't use it when hands are visibly soiled because it will not rinse away dirt and your hands will not be clean at all!

washing and rinsing is actually more effective than alcohol or other chemicals if there is solid matter present b/c they can't penetrate the dirt/poop/whatever.

it's the same on inanimate objects like cages

Term

Tissue necrosis seen in gangrenous forms of mastitis caused by Staphylococcus aureus is attributed to staphylococcal…

Definition
ALPHA TOXIN
Term

The minimum inhibitory concentration (MIC) of an organism for a particular drug is equivalent to its minimum bactericidal concentration (MBC) for the same drug

Definition

No. The MIC is how much to inhibit growth, not to kill the bacteria (MBC). there might still be viable bacteria in the solution at MIC.

Term

If an abscess is not drained, live bacteria contained within the pus will escape into the surrounding tissues and blood stream

Definition

Not necessarily true, in the case of a long standing absess, usually the area is walled off by fibrin from surrounding tissue. Pus is an accumulation of dead leukocytes and thus is drained out of the body

Term

Isolation of numerous microorganisms from a normally sterile body site without the presence of inflammatory cells should be viewed with suspicion.

Definition

True, microorganisms that should not be present should trigger an immune response, if they do not, test that isolated them should be examined

Term

 

Plasmids are transferred between bacteria via bacteriophage

 

Definition

This is not true, some plasmids can transfer  themselves, bacteriophages can transfer information by packaging some of DNA from a host cell and injecting it (generally or specifically) into a 2nd bacteria

(plasmids can be conjugative, mobilizing or non mobilizing - not all transfer themselves but none are transferred by bacteriophage)

 

Term

A bacterial isolate that grows in the absence of oxygen is classified as an anaerobe.

Definition

This is not necessarily true, there are also facultative anaerobes which can tolerate oxygen and can also grow without. It is not strictly just an anaerobe.

Term

Bacteria can be visualized by bright-field microscopy using 100x oil-immersion objective.

Definition

Not true, to see bacteria following staining one should use a 1000x magnification as bright field only shows bacteria up to .2 um in size.

Term

Disease is not an inevitable consequence of infection.

Definition

True, infection can be carried by a chronic patient and shed into the environment w/out the carrier actually being sick. Also bacteria can live in a state of lysogeny w/ bacteriophages and not be “sick” until lysogeny ends.

Term

Fimbriae (pilli) have specialized function in bacterial gene transfer.

Definition

True  - sex pilli are formed from a donor cell and 1 strand of DNA is transferred, at which time another complementary strand is synthesized.

Term

Give one example of an activity that supports the philosophy of “prudent use of antimicrobials” in order to control population wide antimicrobial resistance

Definition

Working to improve compliance in affected patients, if someone does not finish a route of antimicrobials, they have chance of illness again because the disease could come back and be more resistant after mutation

(education)

(prudent use of drug)

Term

 

In a laboratory bacterial killing assay, Penicillin G at a concentration of .3 micrograms/ml caused a 99.9% reduction in bacterial numbers. However, in the same assay with the same inoculum, penicillin G at a concentration of 300 micrograms/ml caused only 10% reduction in bacterial numbers. Bacteria that survived the drug treatments, when retested, were susceptible to penicillin G and were indistinguishable from the original bacterial population.

 

             What is the principal mode of action of penicillin G on bacteria?

             How could the bactericidal action of penicillin G be negated by increasing concentrations of the drug, without changing the inherent properties of the bacterium?       

 

Definition

 

1: Disrupts the cell wall by not allowing cross-linking of peptidoglycan (correct) more info - this only happens during development; not to fully grown bacteria

 

2: Pharmokinetics follows 1st rate order kinetics, meaning 1 molecule of drug is consumed for every 1 receptor, all receptors could be bound with drug, yielding no response when penicillin concentration elevates.(partial credit)

real answer: penicillin only works on actively growing populations! if you've killed off the majority of the growing bacteria quickly, then the population is not actively growing. thus a higher concentration of the drug is actually less effective in killing bacteria

 

 

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