Pearson Chapter 14 Flashcards
What cellular structure protects bacteria from drying out?
Glycocalyx
What type of microbe has lipid A?
Gram-negative bacteria
Which general group of microbes cannot be isolated in pure culture?
Viruses
All of the following might lead to a disease caused by an opportunistic pathogen EXCEPT __________.
immune suppression
an encounter with an infected animal
hormonal changes
changes in diet
an encounter with an infected animal
Human normal microbiota begin to develop __________.
during birth
E. coli living in the colon of a human is an example of a _________ relationship.
mutualism
Rabies is an example of a zoonosis that is hard to control because __________.
Its reservoir contains both domestic and sylvatic animals
If an individual is a carrier of an infectious disease, he is __________.
both asymptomatic and infective
A Deadly Carrier
In 1937, a man employed to lay water pipes was found to be the source of a severe epidemic of typhoid fever. The man, an asymptomatic carrier of Salmonella enterica serotype Typhi, the bacterium that causes typhoid, habitually urinated at his job site. In the process, he contaminated the town’s water supply with bacteria from his bladder. Over 300 cases of typhoid fever developed, and 43 people died before the man was identified as the carrier.
Part A
How was this carrier identified?
sputum sample
nasal swab
throat swab
urine culture
urine culture
A Deadly Carrier
In 1937, a man employed to lay water pipes was found to be the source of a severe epidemic of typhoid fever. The man, an asymptomatic carrier of Salmonella enterica serotype Typhi, the bacterium that causes typhoid, habitually urinated at his job site. In the process, he contaminated the town’s water supply with bacteria from his bladder. Over 300 cases of typhoid fever developed, and 43 people died before the man was identified as the carrier.
Based on the data supplied, what was the approximate mortality rate for this outbreak?
0.14 %
1 %
14 %
43 %
(43 / 300) × 100 = 14 %
A Deadly Carrier
In 1937, a man employed to lay water pipes was found to be the source of a severe epidemic of typhoid fever. The man, an asymptomatic carrier of Salmonella enterica serotype Typhi, the bacterium that causes typhoid, habitually urinated at his job site. In the process, he contaminated the town’s water supply with bacteria from his bladder. Over 300 cases of typhoid fever developed, and 43 peo
What is the reservoir for this disease organism, Salmonella enterica serotype Typhi?
dogs
humans
cats
horses
humans
How could this epidemic be stopped without firing the worker?
Educate the worker about personal hygiene and use of an outhouse or designated bathroom. Instruct him to thoroughly wash his hands with clean soap and water after using the facilities.
What are the clinical signs and symptoms of typhoid fever?
fever and rose-spotted rash
What is a relationship called between two types of organisms in which one benefits while the other remains unaffected?
Commensalism
What is a zoonosis?
A zoonosis is a disease with an animal reservoir from which the disease can spread to humans.
A new drug blocks the adhesins on the surface of a bacterial pathogen. What would likely be the major effect of this drug?
It will prevent infection by this pathogen.
Which of the following is an example of the parenteral route?
A pathogen crosses the placenta and infects a fetus.
A person steps on a nail.
A person rubs his or her eyes with contaminated fingers.
A pathogen enters the body through a hair follicle.
A person steps on a nail.
Infection and disease are NOT the same thing because __________.
disease does not necessarily result from an infection
On which microbes do glycoproteins serve as adhesion factors?
Bacteria and viruses
While investigating a newly discovered Gram-negative bacterium, you find that when the bacteria die, the host experiences severe fever and inflammation. You suspect that the bacterium has __________ in its outer wall membrane
lipid A
In an asymptomatic individual, which of the following might still be detectable?
leukocytosis
Which of the following is NOT a reason why bacterial capsules are effective in the inhibition of phagocytosis?
They are ineffective at stimulating the host’s immune response.
They make it difficult for phagocytes to surround and grip the bacterial cell.
They are usually made of chemicals normally found in the body.
They contain chemicals that are lethal to phagocytes.
They contain chemicals that are lethal to phagocytes.
A patient’s immune system is typically fully responsive during which of the following stages of disease?
decline
An epidemiologist collects drinking glasses, tissues, and bed sheets from the apartment of an individual infected with a particular disease. Which of the following modes of transmission is being investigated for this disease?
indirect contact transmission
What is the difference between the terms infection and disease?
Infection refers to the invasion of a pathogen into the body, while disease means that the body’s normal function is disrupted.
What is an example of a sign (as opposed to a symptom) of disease?
A rash
How do the enzymes hyaluronidase and collagenase increase bacterial virulence?
By allowing bacteria to invade deeper into tissues, making the infection more likely to cause disease
What effect do enterotoxins have?
They affect the gastrointestinal system.
How is Streptococcus pneumoniae able to avoid destruction by a phagocyte?
Their capsules make them “slippery” to phagocytes
Which microorganism requires the low pH inside a phagolysosome in order to reproduce?
Coxiella burnetii
Which of the following microorganisms use M protein to avoid destruction of a phagocyte?
Streptococcus pyogenes
Endotoxins are also known as
Lipid A.
When would endotoxins be released from a bacterial cell?
When the cell dies
Which of the following would be the first sign of an infection that resulted in the release of endotoxin?
Nausea
Pain
Fever
Weakness
Fever
Why is a release of endotoxin into the bloodstream potentially deadly?
It can lower blood pressure and cause the patient to go into shock.
Which of the following features of Salmonella prevent it from being phagocytosed?
Flagella
Fimbriae
Invasins
Flagella
Where do Salmonella pathogens grow and replicate in the infected host?
Inside phagocytes
Where is the site of Shigella attachment in the host?
M cells
How do Shigella cells move between host cells?
They can polymerize actin molecules from the epithelial cells into tail-like structures that propel them from one cell to another.
What is the etiologic agent of typhoid?
Salmonella
An exotoxin that has the ability to kill or damage host cells is referred to as a(n)
Cytotoxin.
Which domain of the A-B toxin binds to cell surface receptors on the host cell?
B domain
How are superantigens different from other types of exotoxins?
Superantigens cause an overstimulation of the host immune system.
A person who attended a picnic early in the day develops a very high fever and is unresponsive by the evening. This person most likely has been exposed to a(n)
Superantigen.
A patient who has been hospitalized with uncontrolled muscle spasms has probably been infected with bacteria that secrete a(n)
Neurotoxin.
What are leukocidins?
Molecules that are capable of destroying phagocytes
Measles viruses are capable of inactivating host defenses by
Suppressing the immune system.
Meningitis and gonorrhea are caused by
Neisseria species.
How do superantigens enable pathogens to hide from the immune system if they actually stimulate the immune system?
They cause the immune system to produce an exaggerated response, distracting it from the actual pathogen.
How can capsules enable bacteria to evade the immune system?
Capsules block the complement biding sites on the surface of the pathogen.
Certain traits that allow pathogens to create infection and cause disease are termed
Virulence factors.
Which of the following enzymes breaks down the “glue” that holds cells together?
Collagenase
Streptokinase
Hyaluronidase
Fibrinolysin
Hyaluronidase
Which of the following virulence factors would be found in Staphylococcus aureus?
Hyaluronidase
Collagenase
Staphylokinase
Streptokinase
Staphylokinase
How do fibrinolysins enhance a pathogen’s virulence?
They break down fibrin proteins that are involved in clot formation, allowing the cells to penetrate deep into damaged skin.
Hyaluronidase and collagenase both allow bacteria to _____.
invade a host’s tissues
Which type of toxin, when secreted, may lead to the disruption of the cells within the gastrointestinal tract?
enterotoxin
A major difference between exotoxins and endotoxins is that endotoxins are _____.
physically part of the bacterial structure
The release of lipid A may lead to _____.
fever, blood clotting, inflammation, and shock
Bacterial capsules work by _____.
protecting the bacterium from engulfment
Some bacteria secrete chemicals that prevent the phagocytic digestion of a bacterium by interfering with the fusion of _____ to the phagosome.
a lysosome
Virulence factors allow microbes to be pathogens. This means that a bacterium with more virulence factors _____.
can more easily infect hosts and cause disease
Why may some bacteria use extracellular enzymes to form blood clots?
Blood clot can hide bacteria from the immune system.
Jerica takes her young son to the pediatrician for regular childhood immunizations. While there, they wait in a room full of sneezing, sniffling, coughing youngsters. Despite making sure that her son stays at least six feet (two meters) from the other children and doesn’t touch any play toys in the waiting room, microbes could still spread to her son by
vehicle transmission.
An example of a mechanical vector is:
a housefly at a picnic
A patient is sickened after being infected with Escherichia coli (E. coli) from consuming contaminated lettuce; this is a type of _______________ disease transmission.
vehicle
A patient with West Nile viral encephalitis asks his nurse practitioner how he could have contracted the disease. The NP explains that the causative virus is carried by infected mosquitoes from birds to people. This is an example of disease transmission through
a biological vector.
Which of the following types of diseases develops rapidly and lasts a short time?
latent disease
subacute disease
acute disease
chronic disease
acute disease
If someone contracts food poisoning from drinking contaminated raw milk, what type of transmission has occurred?
Vehicle Transmission
The viral pathogen that causes cold sores can remain inactive in the body for a long time between disease outbreaks. How is this disease classified?
It is a latent disease.
Microbial contamination always results in infection. T/F
False
A pathogen is best described as
any microorganism that causes disease.
Hepatitis C is an acute disease. T/F
False
Which of the following virulence factors directly contributes to severe inflammation?
collagenase
coagulase
lipid A
kinase
hyaluronidase
lipid A
The degree to which a microbe is able to cause disease is known as its (morbidity/virulence/toxicity).
virulence
Bacterial capsules are (antiphagocytic/cytotoxic/exotoxic) virulence factors.
antiphagocytic
Lipid A is a(n) (cytotoxin/endotoxin/exotoxin) that stimulates the body to release chemicals that cause fever, inflammation, diarrhea, hemorrhaging, shock, and blood coagulation.
endotoxin
Nausea is an example of a (sign/symptom/syndrome) of disease.
symptom
Fecal-oral infections are usually a result of __________.
waterborne transmission
Which of the following is an example of vehicle transmission?
having intercourse
kissing
drinking contaminated water
being bitten by a mosquito
sharing a glass
drinking contaminated water
Which of the following is considered a mechanical vector transmission?
flea transmission of Yersinia
louse transmission of Rickettsia
tsetse fly transmission of Trypanosoma
mosquito transmission of Plasmodium
cockroach transmission of Shigella
cockroach transmission of Shigella
Aerosols may be involved in ________ transmission of pathogens.
droplet
Fomites are
Inanimate objects involved in the indirect contact transmission of pathogens.
Biofilms provide an alternative means for bacteria to attach to surfaces within the body. T/F
True
Virions attach to a target host cell by means of (capsules/fimbriae/ligands).
ligands
A strain of Neisseria gonorrhea has a mutation which has caused it to lose the ability to produce fimbriae and become less virulent as a consequence. What function has this pathogen lost?
the ability to adhere to cells of the body
