Micro Ch25
________ are microbial infections acquired by hospital patients with noninfectious diseases because they are compromised hosts. a. Pathogenic infections b. Healthcare-associated infections c. Immunocompromised infections d. Virulent infections
b
Which of the following is most likely to cause disease? a. injection of 10^1 cells of a highly virulent bacterial species into a mouse b. injection of 10^3 cells of a moderately virulent bacterial species into a mouse c. injection of 10^6 cells of a low virulent bacterial species into a mouse d. injection of 10^5 cells of a highly virulent bacterial species into a mouse
d
All AB toxins have which of the following? Hint 1. [[Exotoxins]] Specific exotoxins are produced by different species of bacteria and can cause very different effects on the host. a. lipid A b. two subunits c. hemolytic activity d. immunogenic properties
b
An outer coat consisting of a dense, well-defined polymer layer surrounding a cell and used in attachment is called a a. lipopolysaccharide layer. b. capsule. c. pilus. d. cytoplasmic membrane.
b
Capsules are particularly important for a. making bacteria less pathogenic. b. protecting bacteria from host defense mechanisms. c. making bacteria more vulnerable to host defense mechanisms. d. allowing bacteria to become more phagocytic.
b
Cytolytic toxins a. cause cell lysis and death. b. are extracellular proteins that cause cell lysis and death by damaging the host cytoplasmic membrane. c. damage host cytoplasmic membrane. d. are extracellular proteins.
b
Exotoxins are ________, but endotoxins are ________. a. lipids / proteins b. proteins / lipopolysaccharide-lipoprotein complexes c. lipopolysaccharide-lipoprotein complexes / proteins d. carbohydrates / proteins
b
Factors that enhance an organism's ability to adhere to host tissues include __________. Hint 1. Adherence. In order to cause an infection or initiate a biofilm, bacteria must be able to attach to surfaces. Some of these factors are covalently attached to bacteria, and others are noncovalently attached. a. adherence enzymes b. fimbriae c. peptidoglycan d. lipopolysaccharide
b
Pathogenicity and virulence differ in that a. virulence only refers to pathogens, whereas pathogenicity refers to any microbe that can cause an infection. b. 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. c. pathogenicity only refers to pathogens, whereas virulence refers to any microbe that can cause an infection. d. virulence refers to the overall ability of a microbe to cause disease, whereas pathogenicity refers to the ability of one microbe to cause disease relative to another.
b
Pathogenicity islands are clusters of genes for virulence factors that are located together on the bacterial chromosome. a. False b. True
b
Salmonella species use ________ to facilitate attachment to gastrointestinal tissue. a. siderophores b. type I fimbriae c. pili d. antiphagocytic proteins
b
Shiga toxin is an enterotoxin that is produced by a. Clostridium tetani. b. Shigella dysenteriae. c. Escherichia coli O157: H7. d. Vibrio cholerae.
b
Staphylococcus aureus and Streptococcus pyogenes strains can produce ________ that cause the severe and sometimes life-threatening symptoms of toxic shock syndrome. a. endotoxin b. superantigen toxins c. cytolytic d. AB toxins
b
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 a. the microbiota. b. the human microbiome. c. pathogens. d. transient microbial flora.
b
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 a. erythemia. b. bacteremia. c. uremia. d. septicemia.
b
Which of the following is NOT important for the adherence of bacteria to host tissues? a. capsule b. lipopolysaccharides c. adhesins d. slime layer
b
A patient is brought to the hospital with severe gastrointestinal distress, including cramps, dehydration and diarrhea. Which of the following symptoms would indicate that the pathogen is Vibrio cholerae? a. bloody, foul smelling diarrhea b. occasional diarrhea but no blood in the stool c. frequent vomiting d. voluminous watery diarrhea
d
Clostridium perfringens causes gas gangrene, a serious infection of the muscle tissues that can lead to amputation. Clostridium are Gram-positive endospore-formers and obligate anaerobes that are killed when exposed to oxygen. Which of the following virulence factors would be most helpful to this organism in establishing an infection? a. a neurotoxin b. nuclease, an enzyme that breaks down nucleic acids c. endotoxin d. collagenase, an enzyme that destroys collagen, which is a major protein of connective tissues
d
Tetanus toxin causes a. severe diarrhea. b. muscles to be unable to contract. c. hemolytic uremic syndrome. d. muscles to be unable to relax.
d
The best term to describe the general process by which microorganisms cause diseases is known as a. infection. b. invasion. c. virulence. d. pathogenesis.
d
Which genus produces hyaluronidase? a. Mycobacterium b. Procholorococcus c. Shigella d. Streptococcus
d
A researcher wanted to determine the LD50 (lethal dose that kills 50% of the infected hosts) for a newly isolated bacterial pathogen. Mice were inoculated with diluted cultures containing between 101 and 107 cells. After two days, all of the mice had died EXCEPT for the uninoculated controls. Which of the following is the most likely explanation? a. This pathogen is highly virulent in mice. b. The pathogen has a very high LD50. c. Mice are not good model animals for this pathogen. d. The pathogen has become attenuated.
a
Decalcification of the tooth enamel is caused by a. lactic acid. b. dextrans. c. lipopolysaccharide. d. formic acid.
a
Endotoxins are comparatively different from exotoxins, because __________. a. All the listed responses are correct. b. endotoxins are not secreted proteins c. endotoxins are associated with more fatalities d. exotoxins can affect sites distant from the infection site
a
Which of the following is a way to prevent attenuation and maintain virulence in a bacterium? a. inoculating an animal with the bacterium b. polymerase chain reaction (PCR) c. antibiotic therapy d. laboratory subculture
a
Which of the following is more likely to cause urinary tract infections? a. fimbriated strains of Escherichia coli b. both fimbriated and non-fimbriated strains of Escherichia coli c. None of the answers are correct. d. non-fimbriated strains of Escherichia coli
a
_______ are toxic proteins released from the pathogen during normal growth. a. Exotoxins b. Macrotoxins c. Microtoxins d. Endotoxins
a
________ is a damage or injury to a host organism that impairs its function. a. Disease b. Transmission c. Trauma d. Infection
a
A patient admitted to the hospital with muscle weakness and paralysis is put on a ventilator because of breathing difficulties. It is determined that the symptoms are the result of a bacterial exotoxin. Which of the following is the most likely source of this toxin? a. a puncture wound b. contaminated water c. canned food d. airborne bacteria
c
Factors that enhance an organism's ability to adhere to host tissues include __________. a. peptidoglycan b. adherence enzymes c. fimbriae d. lipopolysaccharide
c
Native peoples often experience an increase in the incidence of dental caries after they are introduced to imported processed foods. This finding could be explained by the fact that __________. a. Lactobacilli require sucrose in order to form biofilms on tooth surfaces. b. Only purified sucrose and fructose can be fermented or produce acids in the oral cavity. c. Sucrose is required for the production of adhesive dextran by Streptococcus mutans. d. Sucrose and other purified sugars cause pitting of the tooth surfaces.
c
Pathogenicity is the ability a. of the host to inflict damage on the pathogen. b. None of these are correct. c. of the pathogen to inflict damage on the host. d. of the host to resist damage by the pathogen.
c
The diphtheria exotoxin is an A-B toxin that __________. a. is encoded for by genes in the chromosome of Corynebacterium diphtheriae cells b. is found in all Corynebacterium diphtheriae cells c. is found only in Corynebacterium diphtheriae cells that have been infected with lysogenic bacteriophage β d. causes host cell lysis
c
Virulence factors that enhance invasiveness of a pathogen can include __________. a. coagulase b. exotoxins c. All of the listed responses are correct. d. collagenase
c
The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures? a. They must block water and small molecules in order to regulate the exchange of matter and energy with their environment. b. They must provide a rigid structure that maintains an appropriate ratio of cell surface area to volume. c. They are composed of a mixture of lipids and carbohydrates. d. They must permit information transfer between the cell's cytoplasm and the nucleus. e. They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.
e