Module 9

B. Gram-negative bacterial infections

Antibiotics can lead to septic shock if used to treat _______. A. viral infections B. Gram-negative bacterial infections C. Gram-positive bacterial infections D. protozoan infections E. helminthic infestations

A. viral infections

Cytopathic effects are changes in host cells due to _____. A. viral infections B. intoxications C. fungal infections D. bacterial infections E. helminthic infections

B. streptococcal colonization is necessary for periodontal disease

Bacteria that cause periodontal disease have adhesins for receptors on streptococci that colonize on teeth. This indicates that ______. A. streptococci get bacterial infections B. streptococcal colonization is necessary for periodontal disease C. bacteria that cause periodontal disease adhere to gums and teeth D. bacteria that cause periodontal disease adhere to teeth E. streptococci cause periodontal disease

C. coughing and sneezing

The most common portal of exit for a respiratory infection is via ______. A. defecation B. vomiting C. coughing and sneezing D. bleeding E. insect bites

C. The parenteral route

The most common way for the Rabies virus to enter a human host is via bites from animals. What is this portal of entry? A. The skin B. Mucous Membranes C. The parenteral route D. None of the above

A. mucous membranes

The most frequently used portal of entry for pathogens is the ____. A. mucous membranes B. skin C. parenteral route D. none of the above

B. LD50

The potency of a toxin is measured via ______. A. TD50 B. LD50 C. ID50 D. PD50

B. Mucous membranes

Giardia lamblia causes intestinal disease when cysts are swallowed from water contaminated with animal feces. This is an example of which portal of entry? A. Skin B. Mucous membranes C. Parenteral route D. None of the above

A. Skin

Ringworm is a mycosis in which a fungus grows and feeds on keratin within the skin. What is the portal of entry for ringworm? A. Skin B. Mucous membranes C. Parenteral route D. None of the above

A. dose that will cause an infection in 50% of a test population

The ID50 is a ______. A. dose that will cause an infection in 50% of a test population B. dose that will kill some individuals of a test population C. dose that will cause an infection in some individuals of a population D. dose that will kill 50% of a test population

A. antigenic variation

The ability of some microbes, such as Trypanosoma or Giardia to alter their surface molecules and evade destruction by the host’s antibodies is called _____. A. antigenic variation B. lysogenic conversion C. virulence D. cytopathic effect E. cytocidal effect

A. decreases the risk of staphylococcal infection

View the attached table that shows the ID50 for Staphylococcus aureus in wounds with and without the administration of ampicillin before surgery. Based on the data, the administration of ampicillin before surgery ______. A. decreases the risk of staphylococcal infection B. increases the risk of staphylococcal infection C. has no effect on risk of infection D. replaces tetracycline E. The answer cannot be determined based on the information provided

D. Treponema pallidum

View the table of ID50 values. Which of the following organisms is least virulent? A. E. coli O157:H7 B. Legionella pneumophila C. Shigella D. Treponema pallidum

B. Legionella pneumophila

View the table of ID50 values. Which of the following organisms is most virulent? A. E. coli O157:H7 B. Legionella pneumophila C. Shigella D. Treponema pallidum

A. When the pathogen dies.

When would endotoxins be released from a bacterial cell? A. When the pathogen dies. B. When the pathogen attaches to a host cell in the human body. C. When the pathogen moves toward a energy source. D. During bacterial conjugation. E. When the pathogens forms a provirus

C. B domain.

Which domain of the A-B toxin binds to cell surface receptors on the host cell? A. Both the A and B domains have the ability to bind to cell surface receptors. B. A domain. C. B domain. D. A-B toxins do not bind to cell surfaces.

C. part of the gram-negative cell wall

Endotoxins are _____. A. associated with gram-positive bacteria B. molecules that bind nerve cells C. part of the gram-negative cell wall D. excreted from the cell E. A-B toxins

A. Lipid A

Endotoxins are also known as _____. A. Lipid A B. cytokines C. prostaglandins D. interleukin-1 E. enzymes

B. false

Endotoxins are enzymes A. true B. false

C. Parenteral route

A knife wound is an example of which portal of entry? A. Skin B. Mucous membranes C. Parenteral route D. None of the above

A. resists phagocytosis

An encapsulated bacteria can be virulent because the capsule ____. A. resists phagocytosis B. is an endotoxin C. is an exotoxin D. destroys host tissues E. allows bacteria to grow faster

C. membrane disrupting toxin

An exotoxin that makes channels in membranes is referred to as a(n) _____. A. superantigen B. A-B toxin C. membrane disrupting toxin D. endotoxin

B. false

Disease can often be caused by one or two cells entering the human host. A. true B. false

A. A much larger dose of staphylococcal enterotoxin is needed to cause symptoms, compared to that of Shiga toxin.

Given that the LD50 for staphylococcal enterotoxin is 1350 ng/kg and the LD50for Shiga toxin is 250 ng/kg in mice, which of the following statements is true? A. A much larger dose of staphylococcal enterotoxin is needed to cause symptoms, compared to that of Shiga toxin. B. The parenteral route is the preferred portal entry for Shigella bacteria. C. The gastrointestinal route would not be a preferred portal of entry for the Shigella bacteria. D. A much larger dose of Shiga toxin is needed to cause symptoms, compared to that of staphylococcal enterotoxin.

A. Superantigens cause an overstimulation of the host immune system.

How are superantigens different from other types of exotoxins? A. Superantigens cause an overstimulation of the host immune system. B. Superantigens only act against host neurons. C. Superantigens must be endocytosed into a target cell before becoming active. D. Superantigens are comprised of two functional domains.

A. the toxin does not have enzymatic activity

If an A-B toxin is missing its A component it cannot cause an intoxication because ____. A. the toxin does not have enzymatic activity B. the toxin will get degraded in the cell C. the toxin cannot bind to its target D. the toxin cannot be produced

C. the toxin cannot bind to its target

If an A-B toxin is missing its B component it cannot cause an intoxication because ____. A. the toxin does not have enzymatic activity B. the toxin will get degraded in the cell C. the toxin cannot bind to its target D. the toxin cannot be produced

C. Transduction

Nonpathogenic V. cholerae can acquire the cholera toxin gene via lysogenic conversion. What process is involved? A. Phagocytosis B. Conjugation C. Transduction D. Transformation

C. mucous membranes only

Polio is transmitted by ingestion of water contaminated with feces containing poliovirus. What portal of entry does poliovirus use? A. skin only B. parenteral only C. mucous membranes only D. skin and parenteral E. skin, parenteral, and mucous membranes

D. antibiotic resistance

R factors are plasmids that carry ____ genes. A. toxin B. capsule C. fimbriae D. antibiotic resistance E. metabolic

C. iron

Siderophores are bacterial proteins that bind to ____. A. antibodies B. red blood cells C. iron D. white blood cells

C. cytokines

Superantigens produce intense immune responses by stimulating lymphocytes to produce ___. A. endotoxins B. exotoxins C. cytokines D. leukocidins E. interferons

D. superantigens

Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to _____. A. A-B toxins B. lipid A C. membrane-disrupting toxins D. superantigens E. erythrogenic toxin

D. all of the above

Symptoms of protozoan and helminthic diseases are due to _____. A. tissue damage caused by growth of parasites B. waste products excreted by parasites C. products released from damaged tissues D. all of the above

E. Numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

Which of the following contributes to the virulence of a pathogen? A. Numbers of microorganisms that gain access to a host B. Evasion of host defenses C. Toxin production D. Numbers of microorganisms that gain access to a host and evasion of host defenses E. Numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production

D. cell walls

Which of the following does NOT contribute to the symptoms of a fungal disease? A. capsules B. toxins C. allergic response of the host D. cell walls E. metabolic products

C. Diarrhea

Which of the following is not a symptom of endotoxin release? A. Chills B. Fever C. Diarrhea D. Aches E. Shock

C. Fever

Which of the following would be the first sign of an infection that resulted in the release of endotoxin? A. Pain B. Weakness C. Fever D. Nausea

C. Hair follicle

Which of these is not considered entry via the parenteral route? A. Injection B. Bite C. Hair follicle D. Surgery

C. E. coli O157:H7 - 27 mg/kg

Which of these toxins is the least deadly given their LD50 values? A. Sarin - 17 mg/kg B. VX nerve gas - 0.14 mg/kg C. E. coli O157:H7 - 27 mg/kg D. Tetanus toxin - .000002 mg/kg

D. Tetanus toxin - .000002 mg/kg

Which of these toxins is the most deadly given their LD50 values? A. Sarin - 17 mg/kg B. VX nerve gas - 0.14 mg/kg C. E. coli O157:H7 - 27 mg/kg D. Tetanus toxin - .000002 mg/kg

B. Shigella flexneri, a gram-negative bacterium that causes dysentery.

Which one of the following contains endotoxins? A. Streptococcus pyogenes, a gram-positive bacterium that causes strep throat. B. Shigella flexneri, a gram-negative bacterium that causes dysentery. C. Candida albicans, a fungus that causes many secondary infections. D. Plasmodium falciparum, a protist that causes malaria.

A. Pathogenicity

_____ describes the ability of a pathogen to overcome host defenses and cause disease. A. Pathogenicity B. Virulence C. Epidemiology D. Adherence