Micro ch.25

What is the difference between adherence and colonization?

Colonization occurs when a microbe begins to grow in host tissues whereas adherence occurs when the microbe initially attaches

An endogenous pyrogen is

a chemical produced by a host's own immune system that causes fever

Which of the following is a way to prevent attenuation and maintain virulence in a bacterium?

inoculating an animal with the bacterium

The ability of a pathogen to enter a cell, spread, and cause disease is termed

invasion

Which of the following is a major growth-limiting micronutrient that influences microbial growth?

iron

Decalcification of the tooth enamel is caused by

lactic acid

The α-toxin of Clostridium perfringens is

lecithinase

Exotoxins are ________, but endotoxins are ________

proteins / lipopolysaccharide-lipoprotein complexes

Which of the following is NOT a physiological effect of endotoxin exposure?

rapid increase in the numbers of lymphocytes

Influenza virus targets

respiratory epithelium

Pathogens that have entered the bloodstream and are producing toxins are the cause of

septicemia

The spread of pathogens through the blood and lymph systems that results in a bloodborne systemic infection is called

septicemia

Septicemia is an example of a

systemic infection

Staphylococcus aureus and Streptococcus pyogenes strains can produce ________ that cause the severe and sometimes life-threatening symptoms of toxic shock syndrome.

superantigen toxins

________ organisms are valuable in the production of vaccines.

Attenuated

Which of the following pathogens does NOT use capsules or a slime layer for attachment?

Vibrio cholera

Which of the following is NOT an example of an AB toxin?

hemolysins

Which of the following is an important factor in the development of dental caries?

high sugar diet

Which of the following does NOT affect pathogen growth?

temperature B. pH C. availability of microbial nutrients

The collective term for the organisms living on or in the human body, as opposed to a general term for organisms in an environmental habitat, is

the human microbiome

________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts.

Healthcare-associated infections

________ is the growth of microorganisms NOT normally present within a host.

Infection

The dose of an antigen that kills 50% of animals in a test group and is used to estimate the virulence of a pathogen is known as

LD50 (lethal dose50)

________ in saliva cleaves glycosidic linkages in the peptidoglycan that is present in bacterial cell walls, weakening the wall and potentially causing cell lysis.

Lysozyme

Which of the following is NOT a subunit of lipopolysaccharide (LPS)?

M protein

Compared with an endotoxin, would a bacterial exotoxin generally be more likely to function after it had been significantly heated?

No, because exotoxins are heat-labile and less resistant to heating than endotoxins

Which of the following does NOT occur during the development of dental caries?

Oral microflora produce high concentrations of exoenzymes when sucrose is present.

Which of the following toxins is NOT a cytolytic exotoxin?

Shiga toxin

Shiga toxin is an enterotoxin that is produced by

Shigella dysenteriae

Which genus produces hyaluronidase?

Streptococcus

The condition that results when some bacteria are shed in the bloodstream and distributed to distant parts of the body but do not reproduce in the blood is called

bacteremia

Lysozyme is found throughout our bodies to protect us from infection. Some bacteria are able to evade this defense

by altering their peptidoglycan.

An outer coat consisting of a dense, well-defined polymer layer surrounding a cell and used in attachment is called a

capsule

All of the following are enzymes that increase virulence EXCEPT

cellulases

Staphylococcus aureus produces ________, leading to fibrin clots that protect them from attack by host cells.

coagulase

Growth of a microorganism after entering a host is called

colonization

Streptokinase works to ________ fibrin clots while coagulase works to ________ fibrin clots.

dissolve / promote

True or False: Endotoxins are the secreted products of living cells, whereas exotoxins are cell bound and released in large amounts ONLY when the cells lyse.

false

Which cell structure is important in adherence?

fimbria

Which of the following is more likely to cause urinary tract infections?

fimbriated strains of Escherichia coli

Botulinum toxin and tetanus toxin BOTH block the release of neurotransmitters, but botulinum toxin causes ________, whereas tetanus toxin causes ________.

flaccid paralysis / spastic paralysis

The macromolecules responsible for bacterial adherence that are NOT covalently attached to bacteria are collectively called

glycocalyx

Pathogens that can secrete ________ are more virulent because of the organisms potential to spread in the host.

hyaluronidase

Which of the following hemolysins is a phospholipase?

lecithinase

Adherence factors include ALL of the following EXCEPT

lipopolysaccharide layers

Which of the following is NOT important for the adherence of bacteria to host tissues?

lipopolysaccharides

Which disease CANNOT be prevented via the use of a vaccine generated from an attenuated pathogen?

malaria

Epithelial cells lining the respiratory tract form a

mucous membrane

Tetanus toxin causes

muscles to be unable to relax.

It is thought that attenuation occurs especially in a laboratory setting because

nonvirulent or weakly virulent mutants grow faster in laboratory media when there is no selective advantage to virulence.

Pathogenicity is the ability

of the pathogen to inflict damage on the host.

Patients that are HIV+ are at greater risk of ________ than the average population.

opportunistic infections

Siderophores are

organic molecules that help pathogens take up iron.

Organism X has an LD50 of 2 x 102, and organism Y has an LD50 of 3 x 104. Which organism is more virulent?

organism X

The best term to describe the general process by which microorganisms cause diseases is known as

pathogenesis

Genes for antiphagocytic proteins, exotoxins, and adherence that are clustered together on a bacterial chromosome are called

pathogenicity islands

Pathogenicity and virulence differ in that

pathogenicity refers to the overall ability of a microbe to cause disease, whereas virulence refers to the ability of one microbe to cause disease relative to another.

The process by which white blood cells ingest and kill bacteria is called

phagocytosis

Neisseria gonorrhoeae can cause infection by

producing enzymes that destroy antibodies on the surface of mucosal cells.

Capsules are particularly important for

protecting bacteria from host defense mechanisms

A bacterial infection becomes a disease when

there is tissue damage that impairs host function.

Salmonella species use ________ to facilitate attachment to gastrointestinal tissue.

type I fimbriae

Exotoxins classified as AB toxins damage cells by

using the B subunit to attach to the target cell while the A subunit enters and inhibits protein synthesis.

________ can vary between strains of an organism depending on the ability to adhere, colonize, and invade a host.

virulence

Diptheria toxin is a

AB toxin

Which of the following is a category of exotoxin?

cytolytic toxin

Because they are Gram negative, E. coli, Salmonella, and Shigella all produce

endotoxins

The following bacterial genera are all implicated in dental caries EXCEPT

Borrelia

________ are toxic proteins released from the pathogen during normal growth.

Exotoxins

________ is a damage or injury to a host organism that impairs its function.

Disease

Which of the following is a reason that specific pathogens tend to infect specific tissues?

There are chemical and physical differences between tissues

Which of the following is TRUE about flagella?

They may be involved in adherence to a lesser extent than pili and fimbriae

Following exposure to a pathogen, events leading to disease—in the correct order—are

adherence, invasion, infection, toxicity

Receptors on the surface of pathogens that are made of glycoproteins and lipoproteins are called

adhesions

Cytolytic toxins

are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane.

The decrease or loss of virulence of a pathogen is referred to as

attenuation