Chapter 24, 25, 26

Which is true of listeriosis?

-It is a foodborne disease. -It may result in meningitis. -It is usually asymptomatic in healthy people. -It is caused by an organism that can grow at refrigerator temperatures.

Which is true about C. botulinum?

-It is anaerobic. -It may form spores. -It produces a neurotoxin. -It does not grow well below pH 4.5.

Which is true of the Clostridium botulinum toxin?

-It is heat-sensitive. -It is a neurotoxin. -It blocks nerve to muscle signal transmission. -It is a two-part toxin.

Most bacterial intestinal infections may be traced to

-Vibrio spp. -C. jejuni. -Salmonella spp. -Enterobacteriaceae.

Pseudomembranous colitis is associated with infections caused by which of the following?

Clostridium difficile

The cause of infectious mononucleosis is

Epstein-Barr virus.

T/F: Prions are small single-stranded pieces of RNA.

False

T/F: The CNS is an "immunologically privileged" site, which means that the immune response in these sites is enhanced.

False

Which of the following statements regarding Vibrio vulnificus infections in FALSE?

People with V. vulnificus infection always develop life-threatening sepsis.

Which of the following is NOT a sign or symptom of botulism?

Spastic paralysis

Please choose the statement that best describes the normal microbiota of the nervous system.

There is no normal microbiota present.

T/F: The saliva of asymptomatic carriers of herpes simplex is commonly infectious.

True

Most cases of Salmonella gastroenteritis have a(n)

animal source.

Most initial cases of dengue fever are very mild or even asymptomatic. When a second infection with a different serotype of the five known dengue viruses occurs,

dengue hemorrhagic fever may develop, due to antibody-dependent enhancement that facilitates viral entry into macrophages.

The most commonly identified waterborne illness in the United States is

giardiasis.

Which of the following may be transmitted by saliva?

infectious mononucleosis

The toxins involved in intestinal infections typically

kill cells by inhibiting protein synthesis AND modify cell physiology resulting in increased secretion of water and electrolytes.

The menigococcus attach to the mucus membrane via

pili.

The principal mode of transmission of rabies is through

saliva.

The symptom at the site of an animal bite that suggests rabies as a possible diagnosis is

tingling or twitching.

What is the difference between 'bacteremia' and 'septicemia?'

Bacteremia is the presence of living, multiplying bacteria in the bloodstream. Septicemia is the presence of endotoxins, but not necessarily of living microbial agents.

Which of the following about giardiasis is FALSE?

Signs and symptoms include fever and diarrhea.

Food contaminated with Clostridium botulinum often

appears normal.

Why is it important to learn about rabies when only a few cases occur in the United States each year?

-The US isn't the entire world. Rabies might be more common in other areas, and it's important to understand due to its lethality. -The only reason why rabies isn't common in the US is due to our lack of interaction with animal carriers. We could very easily have an outbreak on our hands if we don't know the warning signs to watch for that we've learned about by studying the virus and disease. -Rabies can never be completely eliminated-it has too many different animal reservoirs/carriers. As such, we need to remain constantly aware of how to protect human populations, both by preventing and treating the illness. We can only do that by learning about it.

Which of the following invade(s) intestinal cells? 1. Shigella species 2. Vibrio cholerae 3. Helicobacter pylori 4. Giardia lamblia

1

Which of the following produce functionally similar/identical toxins? 1. Shigella dysenteriae 2. E. coli O157:H7 3. Vibrio cholerae 4. Giardia

1 and 2

Sepsis pathogenesis: Please place the statements in the correct order to show your understanding of sepsis pathogenesis.

1. Bacteria from infection anywhere in the body (such as lungs or kidneys) enter the bloodstream. 2. Macrophages and neutrophils release pro-inflammatory cytokines in response to microbial products. 3. Complement pathway is activated, amplifying the inflammatory response. 4. Widespread, self-stimulating dysregulated inflammatory response occurs. 5. Dysregulated inflammatory response causes disseminated intravascular coagulation (DIC). 6. DIC leads to hemorrhage and multi-organ failure. 7. Shock and death result when blood pressure falls so low that the heart and other vital organs stop functioning.

SBE pathogenesis: Please place the statements regarding subacute bacterial endocarditis into the correct order to show your understanding of the pathogenesis of this disease.

1. Causative bacteria enter the blood during tooth brushing, dental procedures, or trauma. 2. The bacteria get trapped in thin blood clots in hearts with deformed valves or areas of disturbed blood flow. 3. The bacteria multiply in the clots, forming a biofilm that protects them from phagocytosis and medications. 4. The clot increases in size around the multiplying bacteria, and becomes a fragile mass. 5. Pieces of the infected clot break off into the bloodstream, forming septic emboli. 6. Emboli block blood vessels, leading to tissue death and sometimes aneurysm.

Please place the statements into the correct order to show your understanding of rabies pathogenesis.

1. Rabies virus enters the body by bite from infected animal. 2. Virus multiplies in cells at the site of the animal bite. 3. Virus enters a sensory neuron and travels to the spinal cord. 4. Virus travels up the spinal cord to the brain. 5. After entering the brain, the virus multiplies extensively, causing encephalitis. 6. Virus spreads via multiple nerves to other body tissues, including salivary glands and the heart.

If a person is at risk of getting rabies, what is the typical therapy given to prevent disease development and thus to save the person's life?

Administration of anti-rabies virus antibodies and the rabies vaccine

Epstein-Barr virus may become latent in

B cells.

Which of these bacteria require a special medium and microaerophilic conditions?

Campylobacter jejuni

Corneal implants have been implicated in a few cases of

Creutzfeldt-Jakob.

Which of the following statements about E. coli infections is FALSE?

E. coli O157:H7 infections should be treated promptly with antibiotics.

A treatment given to counteract the effect of shiga toxin would also decrease the severity of infections caused by

E. coli O157:H7.

Which of the following best describes how Helicobacter pylori causes ulcers and cancer?

Epithelial cells are damaged by a combination of products released by H. pylori and immune cells that in turn, reduces mucus production, which leads to stomach acids destroying the stomach tissue.

Which of the following best describes how Helicobacter pylori infections may lead to cancer?

H. pylori doesn't actually cause the cancer, but rather, as the stomach cells go through mitosis to replace the tissue damage caused by the stomach acids in the absence of the protective mucus, some cells mutate into cancer cells.

Comparison of hepatitis infections: Drag the statements to their correct category to distinguish between the various types of hepatitis virus infection.

Hepatitis C - Transmission through blood contact, direct contact transmission through sexual activity, vertical transmission - Estimated that more than 4 million Americans are infected by this RNA virus of the Flaviviridae family - Chronic infection and liver damage are common, and treatment can involve the use of ribavirin Hepatitis A or E -Fecal- oral transmission or vehicle transmission -Caused by non-oncogenic RNA viruses exhibiting low virulence - Outbreaks linked to unhygienic food handling, eating shellfish, or traveling to developing countries Hepatitis B -The incubation period is 10-15 weeks and can lead to chronic infections and the development of hepatocellular carcinoma - Treatment involves interferon; a recombinant vaccine is available -Transmission through blood contact, vertical transmission

The cell inclusion bodies shown in the figure below are called _______; they are characteristic of the disease ______.

Negri bodies; rabies

Epidemics of meningitis appear to involve

Neisseria meningitidis.

Which of the following best describes the pathogenesis of rabies?

Rabies virus enters the body via an infected-animal bite, then replicates within surrounding tissues before traveling to the brain where it replicates until host death.

The more severe form of African sleeping sickness is called the

Rhodesian form.

The principal cause of dental caries is

S. mutans.

Which of the following statements regarding sepsis and septic shock is TRUE?

Sepsis initially starts due to an overstimulation of the inflammatory response.

Which of the following statements about shigellosis is FALSE?

Shigella dysenteriae is common in the United States.

Which of the following bacteria-resevoir pairs is INCORRECT?

Shigella species - chicken

Who determined that the cholera outbreak in 1850s London was due to contaminated water and approached the problem by removing the pump handle at the contaminated site?

Snow

Please choose the microorganism that is the most common cause of bacterial meningitis in adults to test your understanding of this disease.

Streptococcus pneumoniae

Why are such a high percentage of infant botulism cases associated with ingestion of honey?

There can be endospores from C. botulinum in honey. They may germinate in the intestines of infants following consumption of honey, leading to colonization and pathogenesis as the bacteria begin forming botulism toxin. Adults' normal intestinal microbiota will out-compete the new microbes, but very young infants may not yet have this normal flora established.

Which is true about prions?

They cause a degenerative brain condition AND they are a normal brain protein that has folded differently.

T/F: Clostridium botulinum, the causative agent of botulism, has more than one portal of entry: the gastrointestinal tract and the skin.

True

T/F: Dysentery is the name given to a diarrheal illness in which blood and pus is present in the feces.

True

T/F: Meningoencephalitis and African sleeping sickness are both caused by protozoans.

True

T/F: Salmonella gastroenteritis can be prevented by adequately cooking food, particularly poultry.

True

T/F: Viral meningitis is much more common than bacterial meningitis

True

T/F: When a person becomes infected with the Epstein-Barr virus (EBV), a member of the herpesvirus family, they are infected for life. They may occasionally suffer reactivation events that may make them infectious to other individuals once again.

True

Determine whether the statements describe characteristics of viral meningitis versus viral encephalitis.

Viral Meningitis -Tissues infected: Infects the outer covering of the brain and spinal cord - Disease severity: Typically LESS severe (compared to the other) - Examples of causative agents: Coxsackie viruses and echoviruses Viral Encephalitis -Tissues infected: Infects the brain tissue - Typically MORE severe (compares to the other) -Examples of causative agents: Arboviruses

Why might it be more difficult to prepare a vaccine against noroviruses than against rotaviruses?

We haven't been able to culture noroviruses in a lab setting yet. Without a starting culture, we can't create a vaccine.

Helicobacter pylori is, in part, able to survive in the stomach by its ability to produce

ammonia from urea.

The central nervous system (CNS) may become infected through the

bloodstream, nerves AND extensions from bone.

To determine the causative agent of a central nervous system (CNS) infection, a sample is taken from the

cerebrospinal fluid.

The animal(s) most often associated with Campylobacter jejuni is/are

chickens.

In order to culture the organism responsible for tularemia, the growth media must contain

cysteine.

If a Salmonella strain developed the ability to better resist low pH, the infectious dose (ID) of the organism would

decrease.

The most common infectious disease of humans is

dental caries.

Antibody-dependent enhancement (ADE), that explains the pathogenesis of dengue hemorrhagic fever and dengue shock syndrome, can best be described as

failure of pre-existing anti-dengue antibodies to neutralize a second dengue virus serotype, instead facilitating viral entry into host cells.

The most common chronic blood-borne infection in the U.S. is

hepatitis C

Most North American outbreaks of Cyclospora cayetanensis have been associated with

imported leafy vegetables and berries.

When Gram-negative bacteria are multiplying in the bloodstream, sepsis/septic shock can result. This is due to binding of endotoxin to toll-like receptors (TLRs) on _________ and neutrophils, provoking an uncontrolled release of pro-inflammatory _________ and activating the complement cascade. These events result in a widespread, self-stimulating inflammatory response.

macrophages; cytokines

Which of the following is caused by a protozoan infection?

malaria

An infection of the membranes covering the brain is called

meningitis.

Viral gastroenteritis that affects people of all ages and usually lasts less than 3 days is caused by

norovirus.

The chronic inflammatory process involving the gums and tissues around the teeth is called

periodontal disease.

The initial attachment required for establishment of an intestinal infection is by

pili.

Meningococcal meningitis is typically acquired through the

respiratory tract.

Viral gastroenteritis in infants and children is most commonly caused by

rotavirus.

Humans acquire the arbovirus that causes epidemic encephalitis by

the bite of an infected mosquito.

Hepatitis A spreads via

the fecal-oral route.

Development of a dengue vaccine has proved challenging because

there are five different viral serotypes, so a multivalent vaccine is needed.

Subacute bacterial endocarditis is usually caused by bacteria

trapped in thin blood clots on a deformed heart valve and multiplying slowly.

African sleeping sickness is transmitted by

tsetse flies.

The development of lymph node enlargement in the region of a skin ulcer after a tick or insect bite or handling of a wild animal suggests

tularemia.