Archive for May 2020

Which is the correct procedure for microbiological aseptic technique when working with cultures in test tubes?

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Which is the correct procedure for microbiological aseptic technique when working with cultures in test tubes?



A) remove cap, wave test tube over flame, dip inoculating loop, put cap back on
B) remove cap, dip inoculating loop, put cap back on
C) remove cap, wave test tube over flame, flame sterilize loop, dip loop into culture, put cap back on
D) remove cap, wave over flame, flame sterilize loop, dip loop into culture, wave test tube over flame again, put cap back on

Answer: D) remove cap, wave over flame, flame sterilize loop, dip loop into culture, wave test tube over flame again, put cap back on

Which of the following is the best definition of generation time in a bacterium?

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Which of the following is the best definition of generation time in a bacterium?



A) the length of time it takes to reach the log phase
B) the length of time it takes for a population of cells to double
C) the time it takes to reach stationary phase
D) the length of time of the exponential phase


Answer: B) the length of time it takes for a population of cells to double

The term microbiome refers to which of the following?

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The term microbiome refers to which of the following?



A) All microorganisms of the same species
B) All of the microorganisms involved in a symbiotic relationship
C) All microorganisms with the same shape
D) All microorganisms in a certain geographic region


Answer: D) All microorganisms in a certain geographic region

Microbes have been revived and grown from:

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Microbes have been revived and grown from:



A) Culture media left in a drawer from last year's Introductory Microbiology lab
B) Amber (fossilized tree sap ~30 million years old)
C) Water inclusions in salt crystals (~250 million years old)
D) All of the above


Answer: D) All of the above

The signs and symptoms of infection with Helicobacter pylori are the result of

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The signs and symptoms of infection with Helicobacter pylori are the result of



A. the production of exotoxins by H. pylori in the intestines.
B. invasion by H. pylori into the mucosa of the large intestine.
C. invasion by H. pylori into the mucosa of the stomach.
D. the production of toxins by H. pylori in contaminated food.
E. damage to the lining of blood vessels by H. pylori.


Answer: C. invasion by H. pylori into the mucosa of the stomach.

All of the following statements about Vibrio cholerae enterotoxin are true EXCEPT

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All of the following statements about Vibrio cholerae enterotoxin are true EXCEPT



A. Toxic activity resides in subunit A
B. Acts on cells of the small intestine
C. Subunit A is responsible for attachment of the toxin to target cells
D. There are two major subunits, A and B


Answer: C. Subunit A is responsible for attachment of the toxin to target cells

A lung specimen from a pneumonia patient contains Gram-negative bacilli. Laboratory test results on the bacteria show they are nonmotile coliforms (in the colon) with a capsule. Which pathogen is the likely cause of the pneumonia?

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A lung specimen from a pneumonia patient contains Gram-negative bacilli. Laboratory test results on the bacteria show they are nonmotile coliforms (in the colon) with a capsule. Which pathogen is the likely cause of the pneumonia?



A. Hafnia
B. Serratia
C. Enterobacter
D. Klebsiella
E. Escherichia coli


Answer: D. Klebsiella

Corynebacterium diphtheriae causes the disease diphtheria by producing diphtheria toxin. The gene encoding the toxin is integrated into bacterial genome during lysogenic conversion. The toxin gene was acquired by which process?

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Corynebacterium diphtheriae causes the disease diphtheria by producing diphtheria toxin. The gene encoding the toxin is integrated into bacterial genome during lysogenic conversion. The toxin gene was acquired by which process?



A. Transformation
B. Transposition
C. Conjugation
D. Transduction
E. Translocation


Answer: D. Transduction

How do group A streptococci camouflage themselves from white blood cells?

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How do group A streptococci camouflage themselves from white blood cells?



A. They grow in chains or pairs.
B. They have hyaluronic acid capsules.
C. They produce streptokinase, which breaks down blood clots.
D. They have protein M in their capsule, which destabilizes complement and interferes with opsonization. E. They stain as Gram-positive.


Answer: B. They have hyaluronic acid capsules.

A 67-year-old diabetic man develops intense pain and swelling on his calf, which acquires a bronze discoloration and develops significant tissue necrosis with hemorrhagic bullae and gas production (gas gangarene). Which of the following is the important contributing agent?

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A 67-year-old diabetic man develops intense pain and swelling on his calf, which acquires a bronze discoloration and develops significant tissue necrosis with hemorrhagic bullae and gas production (gas gangarene). Which of the following is the important contributing agent?



A. Clostridium botulinum
B. Clostridium difficile
C. Clostridium tetani
D. Clostridium perfringens


Answer: D. Clostridium perfringens

The typical lesion of secondary syphilis is

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The typical lesion of secondary syphilis is



A. gummas in bones, in nervous tissues, or on the skin.
B. a painless reddened lesion called a chancre at the site of infection.
C. the development of buboes in the lymph nodes at the site of infection.
D. purulent sore throat.
E. a generalized rash.

Answer: E. a generalized rash.

A 42-year-old patient undergoing treatment with a broad-spectrum antibiotic for several weeks develops profuse, foul-smelling and bloody diarrhea. The patient has fever and abdominal pain. Leukocytes are present in the stool. Cessation of the antibiotic treatment was helpful. Which of the following is the most probable agent of this disease?

04:41 Add Comment

A 42-year-old patient undergoing treatment with a broad-spectrum antibiotic for several weeks develops profuse, foul-smelling and bloody diarrhea. The patient has fever and abdominal pain. Leukocytes are present in the stool. Cessation of the antibiotic treatment was helpful. Which of the following is the most probable agent of this disease?



A. Shigella
B. Vibrio cholerae
C. Salmonella
D. Escherichia coli
E. Clostridium difficile


Answer: E. Clostridium difficile

Regarding Treponema pallidum, al of the following are considered virulence factor EXCEPT

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Regarding Treponema pallidum, al of the following are considered virulence factor EXCEPT



A. Presence of a capsule to protect against phagocytosis
B. Coating of fibronectin protects against phagocytosis.
C. Secrete hyaluronidase, an enzyme that disrupts ground substance, and probably facilitates dissemination of the organism.
D. Outer membrane proteins promote adherence to host cells.


Answer: A. Presence of a capsule to protect against phagocytosis

Profuse watery diarrhea ("rice water stools") leading to dramatic fluid loss and severe dehydration and hypotension, which frequently leads to death are the hallmarks of which toxin activity?

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Profuse watery diarrhea ("rice water stools") leading to dramatic fluid loss and severe dehydration and hypotension, which frequently leads to death are the hallmarks of which toxin activity?



A. Enteric endotoxin
B. Toxin A
C. Shiga toxin
D. Cholera toxin (CT)


Answer: D. Cholera toxin (CT)

The virulence and post-infection complication following infection with Streptococcus pyogenes is determined by which of the following factors:

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The virulence and post-infection complication following infection with Streptococcus pyogenes is determined by which of the following factors:



A. The M protein
B. The M-like protein
C. The C-Carbohydrate antigen located in the cell wall D. The F protein
E. Patient's age and sex


Answer: A. The M protein

A sheepherder has a large black and necrotic lesion (eschar) under his chin that has grown quickly in size. There is no pus, but the patient complains of painful and swollen glands. A Gram-positive bacillus is isolated from the lesion. Which of the following features of the responsible agent is NOT a virulant factor?

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A sheepherder has a large black and necrotic lesion (eschar) under his chin that has grown quickly in size. There is no pus, but the patient complains of painful and swollen glands. A Gram-positive bacillus is isolated from the lesion. Which of the following features of the responsible agent is NOT a virulant factor?



A. Endotoxin
B. Lethal toxins
C. Spore formation
D. Capsule


Answer: A. Endotoxin

Which of the following produces the most potent endotoxin

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Which of the following produces the most potent endotoxin



A. Clostridium tetani
B. Neither Clostridium tetani nor Clostridium botulinum
C. Both Clostridium tetani and Clostridium botulinum
D. Clostridium botulinum


Answer: B. Neither Clostridium tetani nor Clostridium botulinum

All of the following are true about Shiga toxins EXCEPT:

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All of the following are true about Shiga toxins EXCEPT:



A. Upon its activation, the B subunits bind to a host cell and facilitate transfer of the A subunit into the cell. The A subunit disrupt protein synthesis
B. It is a preformed toxin composed from one A subunit and five B subunits.
C. It is a holotoxin composed from one A subunit and five B subunits.
D. It is also produced by some pathogenic Escherichia coli


Answer: B. It is a preformed toxin composed from one A subunit and five B subunits.

All of the following are characteristic of Corynebacterium diphtheriae EXCEPT:

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All of the following are characteristic of Corynebacterium diphtheriae EXCEPT:



A. Avirulent strains acquire their virulence factors from virulent strain through lysogenic phages.
B. Avirulent strains acquire their virulence factors from virulent strain through plasmids.
C. It produces a single "A-B"exotoxin that inhibits eukaryotic protein synthesis.
D. Gram-positive club-shaped rods with metachromatic granules.
E. Humans are the only known reservoir.


Answer: B. Avirulent strains acquire their virulence factors from virulent strain through plasmids.

A patient presents with severe colitis associated with an overgrowth of Clostridium difficile in the lower bowel. The most likely cause of this condition was

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A patient presents with severe colitis associated with an overgrowth of Clostridium difficile in the lower bowel. The most likely cause of this condition was



A. mechanical blockage of the large intestine
B. compromised immune system
C. a stomach ulcer
D. botulinum food poisoning
E. antibiotic therapy


Answer: E. antibiotic therapy

A sexually active 27-year-old man complains of a greenish-yellow discharge from his urethra and difficulty urinating. A Gram-negative diplococcus was seen on the Gram stain. Confirmation by culture requires plating on which of the following media?

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A sexually active 27-year-old man complains of a greenish-yellow discharge from his urethra and difficulty urinating. A Gram-negative diplococcus was seen on the Gram stain. Confirmation by culture requires plating on which of the following media?



A. Lowenstein-Jensen agar
B. Choclate agar
C. EMB agar
D. MacConkey agar
E. Mannitol salts agar


Answer: B. Choclate agar

Rheumatic fever is a sequalae of repeated infection with Streptococcus pyogenes. The pathogenesis involved in this complication is

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Rheumatic fever is a sequalae of repeated infection with Streptococcus pyogenes. The pathogenesis involved in this complication is



A. An immunological response to specific Protein A
B. Antigen-antibody complex precipitation on the valves of the heart
C. Molecular mimicry in which some of the bacterial proteins resmbles those of endocardium
D. An immunological response to the antigen determining the Lancefield classification of the bacterium


Answer: C. Molecular mimicry in which some of the bacterial proteins resmbles those of endocardium

The typical lesion of primary syphilis is

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The typical lesion of primary syphilis is



A. gummas in bones, in nervous tissues, or on the skin.
B. the development of buboes in the lymph nodes at the site of infection.
C. purulent sore throat.
D. a painless reddened lesion called a chancre at the site of infection.
E. a generalized rash.


Answer: D. a painless reddened lesion called a chancre at the site of infection.

Your patient has subacute bacterial endocarditis caused by a member of the viridans group of streptococcus. Which one of the following sites is MOST likely to be the source of the organism?

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Your patient has subacute bacterial endocarditis caused by a member of the viridans group of streptococcus. Which one of the following sites is MOST likely to be the source of the organism?



A. Skin
B. Colon
C. Oropharynx
D. Urethra

Answer: C. Oropharynx

Which type of staphylococcus is more likely to cause uncomplicated urinary tract infections in nonhospitalized hosts, especially sexually active young women?

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Which type of staphylococcus is more likely to cause uncomplicated urinary tract infections in nonhospitalized hosts, especially sexually active young women?



A. Staphylococcus epidermidis
B. Staphylococcus saprophyticus
C. Staphylococcus aureus
D. Staphylococcus intermedius


Answer: B. Staphylococcus saprophyticus

Listeria's virulence is directly related to its ability to

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Listeria's virulence is directly related to its ability to



A. easily become a pathogen in humans.
B. live within cells and thus avoid exposure to the immune system of its host.
C. resist most antimicrobial agents.
D. produce powerful toxins.
E. form very resistant endospores.


Answer: B. live within cells and thus avoid exposure to the immune system of its host.

Which of the following statements regarding the role of protein A in the pathogenesis of infections caused by Staphylococcus aureus is correct?

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Which of the following statements regarding the role of protein A in the pathogenesis of infections caused by Staphylococcus aureus is correct?



A. It is responsible for the rash in toxic shock syndrome.
B. It is directly responsible for lysis of neutrophils.
C. It is a bacterial surface protein that binds to the Fc portion of IgG.
D. It converts hydrogen peroxide into water and oxygen.
E. It is a potent enterotoxin.


Answer: C. It is a bacterial surface protein that binds to the Fc portion of IgG.

The typical lesion of tertiary syphilis is

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The typical lesion of tertiary syphilis is



A. a generalized rash.
B. gummas in bones, in nervous tissues, or on the skin.
C. a painless reddened lesion called a chancre at the site of infection.
D. purulent sore throat.
E. the development of buboes in the lymph nodes at the site of infection.


Answer: B. gummas in bones, in nervous tissues, or on the skin.

The diarrhea associated with enteropathogenic Escherichia coli (EPEC) is the result of:

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The diarrhea associated with enteropathogenic Escherichia coli (EPEC) is the result of:



A. Plasmid-mediated A/E histopathology with disruption of normal microvillus structure resulting in malabsorption and diarrhea
B. Plasmid-mediated invasion and destruction of epithelial cells lining colon
C. Mediated by cytotoxic Shiga toxins (STx-1, STx-2), which disrupt protein synthesis
D. Plasmid-mediated, heat-stable and/or heat-labile enterotoxins that stimulate hypersecretion of fluids and electrolytes


Answer: A. Plasmid-mediated A/E histopathology with disruption of normal microvillus structure resulting in malabsorption and diarrhea

Which of the following components of Steptococcus pyogenes are non-antigenic, i.e., do not elicit the host to produce antibodies against it, thus it is an important virulence factor

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Which of the following components of Steptococcus pyogenes are non-antigenic, i.e., do not elicit the host to produce antibodies against it, thus it is an important virulence factor



A. Group Specific Carbohydrate Antigen (Lancefield's Classification)
B. F Protein
C. Capsule
D. Streptolysin-O
E. M Protein


Answer: C. Capsule

The majority of human infections with Campylobacter species are caused by which of the following?

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The majority of human infections with Campylobacter species are caused by which of the following?



A. Direct contact with carriers of the bacterium
B. Contamination of food, milk, or water with animal feces
C. Direct contact with persons infected with the bacterium
D. Multiplication of the organism in food products


Answer: B. Contamination of food, milk, or water with animal feces

The diarrhea associated with enterotoxigenic Escherichia coli (ETEC) is the result of:

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The diarrhea associated with enterotoxigenic Escherichia coli (ETEC) is the result of:



A. Plasmid-mediated invasion and destruction of epithelial cells lining colon
B. Mediated by cytotoxic Shiga toxins (STx-1, STx-2), which disrupt protein synthesis
C. Plasmid-mediated, heat-stable and/or heat-labile enterotoxins that stimulate hypersecretion of fluids and electrolytes
D. Plasmid-mediated A/E histopathology with disruption of normal microvillus structure resulting in malabsorption and diarrhea


Answer: C. Plasmid-mediated, heat-stable and/or heat-labile enterotoxins that stimulate hypersecretion of fluids and electrolytes

A 37-year-old man has a self-limited with an explosive onset of watery diarrhea and nausea, vomiting, abdominal cramps, headache, and low-grade fever 2 days after winning a sushi eating contest. Which of the following is the cause of the diarrhea?

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A 37-year-old man has a self-limited with an explosive onset of watery diarrhea and nausea, vomiting, abdominal cramps, headache, and low-grade fever 2 days after winning a sushi eating contest. Which of the following is the cause of the diarrhea?



A. Salmonella typhi
B. Vibrio parahaemolyticus
C. Shigella dysenteriae
D. Vibrio vulnificusƒ
E. Vibrio cholerae


Answer: B. Vibrio parahaemolyticus

A young man returned from a backpacking trip in Mexico suffering from a high fever, pain in the abdomen, and watery diarrhea. The emergency room doctor noted a faint rash on the patient's abdomen and chest. A blood specimen was collected and plated on MacConkey agar, incubated at 37°C in ambient air. Lactose-negative colonies grew on the plates. The cultured organism was a Gram-negative rod that did not produce Shiga or Shiga-like toxins. The most likely etiological agent for this man's disease is:

03:45 Add Comment

A young man returned from a backpacking trip in Mexico suffering from a high fever, pain in the abdomen, and watery diarrhea. The emergency room doctor noted a faint rash on the patient's abdomen and chest. A blood specimen was collected and plated on MacConkey agar, incubated at 37°C in ambient air. Lactose-negative colonies grew on the plates. The cultured organism was a Gram-negative rod that did not produce Shiga or Shiga-like toxins. The most likely etiological agent for this man's disease is:



A. Vibrio parahaemolyticus
B. Salmonella typhi
C. Shigella dysenteriae
D. Enterohemorrhagic Escherichia coli


Answer: B. Salmonella typhi

Over 90% of Staphylococcus aureus bacteria can withstand the effect of penicillin. Why?

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Over 90% of Staphylococcus aureus bacteria can withstand the effect of penicillin. Why?



A. They produce Beta-lactamase.
B. Cell division occurs in successively different planes, and the daughter cells remain attached to one another.
C. They produce coagulase.
D. They have loosely organized polysaccharide slime layers.
E. They produce staphylokinase, which dissolves fibrin threads in blood clots.


Answer: A. They produce Beta-lactamase.

"Bluecomb" septicemia in turkeys and other species of fowl (chickens, ducks, emus, parrots, peacocks, pheasants) is caused by:

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"Bluecomb" septicemia in turkeys and other species of fowl (chickens, ducks, emus, parrots, peacocks, pheasants) is caused by:



A. Listeria monocytogenes
B. Erysipelothrix rhusiopathiae
C. Both Erysipelothrix rhusiopathiae and Listeria monocytogenes
D. Neither Erysipelothrix rhusiopathiae nor Listeria monocytogenes


Answer: B. Erysipelothrix rhusiopathiae

Of the following species of mycobacterium, which causes a chronic disease of the skin, mucous membranes, and nerve tissue and has not yet been cultivated in vitro?

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Of the following species of mycobacterium, which causes a chronic disease of the skin, mucous membranes, and nerve tissue and has not yet been cultivated in vitro?



A. Mycobacterium leprae
B. Mycobacterium murium
C. Mycobacterium phlei
D. Mycobacterium paratuberculosis


Answer: A. Mycobacterium leprae

The signs and symptoms of infection with Helicobacter pylori are the result of

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The signs and symptoms of infection with Helicobacter pylori are the result of



A. invasion by Helicobacter pylori into the mucosa of the stomach.
B. the production of exotoxins by Helicobacter pylori in the intestines.
C. invasion by Helicobacter pylori into the mucosa of the large intestine.
D. damage to the lining of blood vessels by Helicobacter pylori.
E. the production of toxins by Helicobacter pylori in contaminated food.


Answer: A. invasion by Helicobacter pylori into the mucosa of the stomach.

Bovine mastitis is caused by:

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Bovine mastitis is caused by:



A. Streptococcus equi
B. Streptococcus mutans
C. Streptococcus agalactiae
D. Streptococcus anginosus
E. Streptococcus bovis


Answer: C. Streptococcus agalactiae

A group of patients was seen on an emergency basis complaining of abdominal cramps and watery diarrhea within 5 hours of attending a picnic in which ham, potato salad, and custard-filled pastries were on the menu. Which of the following is the likely cause of this disease?

03:42 Add Comment

A group of patients was seen on an emergency basis complaining of abdominal cramps and watery diarrhea within 5 hours of attending a picnic in which ham, potato salad, and custard-filled pastries were on the menu. Which of the following is the likely cause of this disease?



A. Replication of virus that prevents reabsorption of water
B. Bacterial adherence and invasion
C. Bacterial colonization and toxin production
D. Preformed bacterial toxin
E. Attachment and disruption of intestinal lining due to parasitic infection


Answer: D. Preformed bacterial toxin

Anthrax, which means "charcoal" in Greek, derives its name from

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Anthrax, which means "charcoal" in Greek, derives its name from



A. its ability to invade the bloodstream and produce toxemia.
B. the staining properties of the bacillus under the microscope.
C. the high mortality it causes in infected individuals.
D. the black eschars it produces on human skin.
E. the airborne endospores it produces.


Answer: D. the black eschars it produces on human skin.

The Quellung reaction is used to diagnose

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The Quellung reaction is used to diagnose



A. Streptococcus pneumoniae.
B. Streptococcus equisimilis.
C. Staphylococcus aureus.
D. Streptococcus pyogenes.
E. Streptococcus agalactiae.


Answer: A. Streptococcus pneumoniae.

The majority of human infections with Campylobacter species are caused by which of the following?

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The majority of human infections with Campylobacter species are caused by which of the following?



A. Direct contact with persons infected with the bacterium
B. Direct contact with carriers of the bacterium
C. Multiplication of the organism in food products
D. Contamination of food, milk, or water with animal feces


Answer: D. Contamination of food, milk, or water with animal feces

The typical lesion of primary syphilis is

03:41 Add Comment

The typical lesion of primary syphilis is



A. gummas in bones, in nervous tissues, or on the skin.
B. the development of buboes in the lymph nodes at the site of infection.
C. a generalized rash.
D. a painless reddened lesion called a chancre at the site of infection.
E. purulent sore throat.


Answer: D. a painless reddened lesion called a chancre at the site of infection.

Which of the following is true of spirochetes?

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Which of the following is true of spirochetes?



A. They are all sexually transmitted
B. They have peritrichous arrangement of flagella
C. They are obligate intracellular organisms.
D. They are able to penetrate a host's tissues.
E. They are Gram-positive.


Answer: D. They are able to penetrate a host's tissues.

The Gardasil vaccine:

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The Gardasil vaccine:



A. Protects against infection will several types of human herpesvirus.
B. Protects against infection with all herpes viruses.
C. Protects against infection will over 100 types of human papillomavirus.
D. Protects against infection with 4 types of human papillomavirus.
E. Protects against infection with HIV.


Answer: D. Protects against infection with 4 types of human papillomavirus.

A lung specimen from a pneumonia patient contains Gram-negative bacilli. Laboratory test results on the bacteria show they are nonmotile coliforms (in the colon) with a capsule. Which pathogen is the likely cause of the pneumonia?

12:42 Add Comment

A lung specimen from a pneumonia patient contains Gram-negative bacilli. Laboratory test results on the bacteria show they are nonmotile coliforms (in the colon) with a capsule. Which pathogen is the likely cause of the pneumonia?



A. Klebsiella
B. Hafnia
C. Serratia
D. Enterobacter
E. Escherichia coli


Answer: A. Klebsiella

The Nucleases (enzymes that hydrolyzes DNA) are considered virulence factor because:

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The Nucleases (enzymes that hydrolyzes DNA) are considered virulence factor because:



A. They destroy the DNA of the macrophages
B. They destroy the DNA of the neutrophils
C. They destroy the Neutrophils Extracellular Traps
D. They attack the DNA of the host cells
E. They attack the DNA of the normal bacterial flora of the host


Answer: C. They destroy the Neutrophils Extracellular Traps

Which type of staphylococcus is more likely to cause uncomplicated urinary tract infections in non-hospitalized hosts, especially sexually active young women?

12:41 1 Comment

Which type of staphylococcus is more likely to cause uncomplicated urinary tract infections in non-hospitalized hosts, especially sexually active young women?



A. Staphylococcus saprophyticus
B. Staphylococcus aureus
C. Staphylococcus epidermidis
D. Staphylococcus intermedius


Answer: A. Staphylococcus saprophyticus

All of the following are characteristic of Corynebacterium diphtheriae EXCEPT:

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All of the following are characteristic of Corynebacterium diphtheriae EXCEPT:



A. Humans are the only known reservoir.
B. It produces a single "A-B"exotoxin that inhibits eukaryotic protein synthesis.
C. Gram-positive club-shaped rods with metachromatic granules.
D. Avirulent strains acquire their virulence factors from virulent strain through lysogenic phages.
E. Avirulent strains acquire their virulence factors from virulent strain through plasmids.


Answer: E. Avirulent strains acquire their virulence factors from virulent strain through plasmids.

The diarrhea associated with Enteropathogenic Escherichia coli (EPEC) is the result of:

12:41 Add Comment

The diarrhea associated with Enteropathogenic Escherichia coli (EPEC) is the result of:



A. Plasmid-mediated, heat-stable and/or heat-labile enterotoxins that stimulate hypersecretion of fluids and electrolytes
B. Plasmid-mediated invasion and destruction of epithelial cells lining colon
C. Plasmid-mediated A/E histopathology with disruption of normal microvillus structure resulting in malabsorption and diarrhea
D. Mediated by cytotoxic Shiga toxins (STx-1, STx-2), which disrupt protein synthesis


Answer: C. Plasmid-mediated A/E histopathology with disruption of normal microvillus structure resulting in malabsorption and diarrhea

The typical lesion of secondary syphilis is

12:40 Add Comment

The typical lesion of secondary syphilis is



A. a painless reddened lesion called a chancre at the site of infection.
B. gummas in bones, in nervous tissues, or on the skin.
C. a generalized rash.
D. purulent sore throat.
E. the development of buboes in the lymph nodes at the site of infection.


Answer: C. a generalized rash.

Bacteria collected from a severely inflamed wound are sent to the lab for analysis. The results come back as follows: Gram-positive cocci in irregular clusters, kinase and coagulase positive, and able to grow in the presence of most antibiotics except vancomycin. The bacteria in the wound are most likely

12:40 Add Comment

Bacteria collected from a severely inflamed wound are sent to the lab for analysis. The results come back as follows: Gram-positive cocci in irregular clusters, kinase and coagulase positive, and able to grow in the presence of most antibiotics except vancomycin. The bacteria in the wound are most likely



A. methicillin-resistant Staphylococcus aureus (MRSA).
B. Staphylococcus epidermidis.
C. Enterococcus.
D. Staphylococcus aureus.
E. Streptococcus pyogenes (group A streptococcus).


Answer: A. methicillin-resistant Staphylococcus aureus (MRSA).

Which of the following organisms causes Yaws?

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Which of the following organisms causes Yaws?



A. Treponema pallidum endemicum
B. Treponema pallidum pallidum
C. Treponema pallidum carateum
D. Treponema pallidum pertenue


Answer: D. Treponema pallidum pertenue

Which of the following statements accurately describes ALL viruses:

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Which of the following statements accurately describes ALL viruses:



A. Virus particles are metabolically inactive.
B. All viral genomes are DNA.
C. Virus growth is exponential.
D. Viruses use their own ribosomes for protein synthesis.
E. Viruses like other microbes divide by binary fission


Answer: A. Virus particles are metabolically inactive.

The typical lesion of tertiary syphilis is

12:39 Add Comment

The typical lesion of tertiary syphilis is



A. purulent sore throat.
B. a generalized rash.
C. the development of buboes in the lymph nodes at the site of infection.
D. gummas in bones, in nervous tissues, or on the skin.
E. a painless reddened lesion called a chancre at the site of infection.


Answer: D. gummas in bones, in nervous tissues, or on the skin.

Greasy Pig Disease is caused by:

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Greasy Pig Disease is caused by:



A. Streptococcus pyogenes
B. Streptococcus porcinus
C. Staphylococcus aureus
D. Staphylococcus hyicus
E. Staphylococcus epidermidis


Answer: D. Staphylococcus hyicus

Which of the following statements about Bacillus anthracis is FALSE?

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Which of the following statements about Bacillus anthracis is FALSE?



A. It produces endospores.
B. It is primarily a disease of humans.
C. It normally dwells in the soil and can survive in the environment for centuries or longer.
D. It has a capsule.
E. It can be lethal even after treatment because antimicrobial drugs do not inactivate accumulated anthrax toxin.


Answer: B. It is primarily a disease of humans.

A 25-year-old woman is seen on an emergency basis while in shock, with generalized flushing of the skin and mucous membranes. A tampon is present in her vagina. Toxic shock syndrome is suspected. Which of the following mechanisms is responsible for the toxic shock syndrome?

12:37 Add Comment

A 25-year-old woman is seen on an emergency basis while in shock, with generalized flushing of the skin and mucous membranes. A tampon is present in her vagina. Toxic shock syndrome is suspected. Which of the following mechanisms is responsible for the toxic shock syndrome?



A. Inhibition of acetylcholine release
B. ADP ribosylation of ribosomal protein
C. Stimulation of G protein
D. Cross-linking of MHC II and TCR proteins
E. Activation of adenylate cyclase


Answer: D. Cross-linking of MHC II and TCR proteins

To overcome drug resistance during long antibacterial treatment of tuberculosis the following should consist of the following steps EXCEPT

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To overcome drug resistance during long antibacterial treatment of tuberculosis the following should consist of the following steps EXCEPT



A. Applying D.D.T. (Direct Decision Therapy) on the skin to lower incidence of infection
B. Initial multidrug (3) to be tapered to two drugs
C. Reference to latest bulletins regarding drug resistance issued by the CDC or FDA
D. Applying D.O.T. (Direct observation therapy)


Answer: A. Applying D.D.T. (Direct Decision Therapy) on the skin to lower incidence of infection

The virulence factors attributed to Listeria monocytogenes include:

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The virulence factors attributed to Listeria monocytogenes include:


A. Cell attachment factors (internalins), hemolysins (listeriolysin O, two phospholipase Cs), and a protein that mediates actin-directed motility (ActA)
B. The organism is a facultative intracellular pathogen
C. The presence of capsule to resist phagocytosis
D. Only 'A' and 'B'
E. All of the above


Answer: D. Only 'A' and 'B'

Which of the following statements concerning viruses is FALSE?

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Which of the following statements concerning viruses is FALSE?



A. Viruses enter a cell to complete the replication they have begun extracellularly.
B. Some viruses have an outer membrane called an envelope.
C. Viral capsids can assume one of three basic shapes.
D. Viruses never contain both DNA and RNA.
E. Tobacco mosaic virus was the first virus to be discovered and characterized.


Answer: A. Viruses enter a cell to complete the replication they have begun extracellularly.

The Streptokinase secreted by Streptococcus pyogenes

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The Streptokinase secreted by Streptococcus pyogenes



A. Lyses leukocytes, platelets, and erythrocytes
B. Lyses blood clots and facilitates spread of bacteria in tissues
C. Degrades complement component C5a
D. Depolymerizes cell-free DNA in purulent material


Answer: B. Lyses blood clots and facilitates spread of bacteria in tissues

What organisms are primarily responsible for human tubercular cases?

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What organisms are primarily responsible for human tubercular cases?



A. Mycobacterium tuberculosis and Mycobacterium bovis
B. Mycobacterium tuberculosis and Mycobacterium avium
C. Mycobacterium fortuitum and Mycobacterium genavense
D. Mycobacterium avium and Mycobacterium genavense


Answer: A. Mycobacterium tuberculosis and Mycobacterium bovis

A 33-year-old soldier has recent weight loss, night sweats, fever, and cough. Results of a PPD (Tuberculin) test show redness and swelling at the site of injection. Radiograph results of the chest show bilateral upper lobe involvement and mediastinal and hilar lymphadenopathy. Which of the following describes the microbe causing this disease?

12:35 Add Comment

A 33-year-old soldier has recent weight loss, night sweats, fever, and cough. Results of a PPD (Tuberculin) test show redness and swelling at the site of injection. Radiograph results of the chest show bilateral upper lobe involvement and mediastinal and hilar lymphadenopathy. Which of the following describes the microbe causing this disease?



A. Gram-negative bacillus
B. Acid-fast staining filamentous
C. Gram-positive coccus
D. Gram-positive bacillus
E. Acid-fast staining bacillus


Answer: E. Acid-fast staining bacillus

A 23-year-old student develops abdominal cramps, nausea, and vomiting approximately 4 hours after eating leftover (almost forgotten) Chinese food. Which of the following is the most likely cause for his ailment?

12:35 Add Comment

A 23-year-old student develops abdominal cramps, nausea, and vomiting approximately 4 hours after eating leftover (almost forgotten) Chinese food. Which of the following is the most likely cause for his ailment?



A. Escherichia coli
B. Bacillus cereus
C. Clostridium difficile
D. Salmonella typhi


Answer: B. Bacillus cereus

Strangles in horses is caused by:

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Strangles in horses is caused by:



A. Streptococcus bovis
B. Streptococcus agalactiae
C. Streptococcus equi
D. Streptococcus anginosus
E. Streptococcus mutans


Answer: C. Streptococcus equi

All of the following statements about Bacillus anthracis are true EXCEPT

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All of the following statements about Bacillus anthracis are true EXCEPT



A. Inhalation may produce severe pneumonia in humans
B. Anaerobic
C. The agent is a straight rod with square ends
D. Human infection can be a localized skin infection
E. Immunization of domestic animals has resulted in only rare illness in humans


Answer: B. Anaerobic

Rheumatic fever is a sequelae of repeated infection with Streptococcus pyogenes. The pathogenesis involved in this complication is

12:33 Add Comment

Rheumatic fever is a sequelae of repeated infection with Streptococcus pyogenes. The pathogenesis involved in this complication is



A. Molecular mimicry in which some of the bacterial proteins resembles those of endocardium
B. An immunological response to specific 'M' protein
C. An immunological response to the antigen determining the Lancefield classification of the bacterium
D. Antigen-antibody complex precipitation on the valves of the heart


Answer: A. Molecular mimicry in which some of the bacterial proteins resembles those of endocardium

Which of the following describes a major component of the Staphylococcus aureus cell wall. It binds to the 'Fc' moiety (stem of the Y-shaped antibody) of IgG, exerting an anti-opsonin (and therefore strongly antiphagocytic) effect

12:32 Add Comment

Which of the following describes a major component of the Staphylococcus aureus cell wall. It binds to the 'Fc' moiety (stem of the Y-shaped antibody) of IgG, exerting an anti-opsonin (and therefore strongly antiphagocytic) effect



A. capsule
B. protein A
C. cytolytic exotoxins
D. superantigen exotoxins
E. DNAse enzymes


Answer: B. protein A

A 37-year-old man has a self-limited with an explosive onset of watery diarrhea and nausea, vomiting, abdominal cramps, headache, and low-grade fever 2 days after winning a sushi eating contest. Which of the following is the cause of the diarrhea?

12:32 Add Comment

A 37-year-old man has a self-limited with an explosive onset of watery diarrhea and nausea, vomiting, abdominal cramps, headache, and low-grade fever 2 days after winning a sushi eating contest. Which of the following is the cause of the diarrhea?



A. Vibrio cholerae
B. Vibrio vulnificus
C. Shigella sonnei
D. Vibrio parahaemolyticus
E. Salmonella typhi


Answer: D. Vibrio parahaemolyticus

PPD (purified protein derivative) or tuberculin is injected intradermally to test whether an individual is infected with tuberculosis. After 48-72 hours post-injection, the test is read by measuring:

12:32 Add Comment

PPD (purified protein derivative) or tuberculin is injected intradermally to test whether an individual is infected with tuberculosis. After 48-72 hours post-injection, the test is read by measuring:



A. The distance the bleb or wheal forms from the injection site
B. The diameter of the bleb or wheal
C. The number of blebs or wheals at the injection site
D. The intensity of the red coloration of the injection site


Answer: B. The diameter of the bleb or wheal

The probable cause for the relapsing nature of relapsing fever caused by Borrelia recurrentis is

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The probable cause for the relapsing nature of relapsing fever caused by Borrelia recurrentis is



A. periodic spore dormancy and activation.
B. organisms that survive and propagate after spirochete-induced fever
C. the sequential appearance of new antibiotic resistant variants.
D. successive appearance of antigenic variants.
E. periodic hormonal fluctuations in the host.


Answer: D. successive appearance of antigenic variants.

Pyoderma in dogs is caused by:

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Pyoderma in dogs is caused by:



A. Staphylococcus intermedius
B. Staphylococcus epidermidis
C. Streptococcus pyogenes
D. Staphylococcus saprophyticus
E. Staphylococcus aureus


Answer: A. Staphylococcus intermedius

The primary function of the hemagglutinin protein is to:

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The primary function of the hemagglutinin protein is to:



A. Permit the release of viral progeny from the cell
B. Attach to sialic acid residues on the cell surface and promote engulfment
C. Transcribe the viral RNA
D. Prevent attachment to red blood cells


Answer: B. Attach to sialic acid residues on the cell surface and promote engulfment

All of the following statements are true about viruses EXCEPT

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All of the following statements are true about viruses EXCEPT



A. Viruses are obligate intracellular parasites
B. Viruses are infectious agents
C. They assemble de novo
D. Some viruses are facultative intracellular parasites
E. Viruses have a genome surrounded by a protein coat


Answer: D. Some viruses are facultative intracellular parasites

Anabolic reactions

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Anabolic reactions



A) require energy
B) release energy
C) break down molecules
D) do not involve energy


Answer: A) require energy

Redox reactions

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Redox reactions



A) transfer energy
B) transfer electrons
C) involve oxidation and reduction
D) are involved in all of the above


Answer: D) are involved in all of the above

Oxygen is vital to the process of aerobic cellular respiration. It allows aerobic organisms to derive a great deal more energy from glucose than anaerobic organisms are able to. What is the vital role that oxygen plays in cellular respiration?

04:21 Add Comment

Oxygen is vital to the process of aerobic cellular respiration. It allows aerobic organisms to derive a great deal more energy from glucose than anaerobic organisms are able to. What is the vital role that oxygen plays in cellular respiration?


A) It is a reactant in glycolysis, necessary for the breakdown of glucose into pyruvic acid.
B) Oxygen is a waste product of Kreb's cycle.
C) Oxygen is required to build the acetyl-CoA molecule.
D) Oxygen is the final electron acceptor in the electron transport chain.


Answer: D) Oxygen is the final electron acceptor in the electron transport chain.

Which of the following would not likely be encoded on a plasmid?

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Which of the following would not likely be encoded on a plasmid?



A) Genes encoding toxins that damage host tissue
B) Genes encoding antibacterial resistance
C) Gene encoding enzymes for glycolysis
D) Genes encoding enzymes for the degradation of an unusual substrate


Answer: C) Gene encoding enzymes for glycolysis

DNA does all but which of the following?

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DNA does all but which of the following?



A) serves as the genetic material passed from parent to offspring
B) remains constant despite changes in environmental conditions
C) provides the instructions for the synthesis of messenger RNA
D) is read by ribosomes during the process of translation


Answer: D) is read by ribosomes during the process of translation

The Ames test is a method to do what?

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The Ames test is a method to do what?



A) Identify a bacterial species
B) Identify whether a chemical is mutagenic
C) Test for bacterial growth on sugars
D) Detect DNA in a sample
E) All of the above


Answer: B) Identify whether a chemical is mutagenic
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