Microbiology Lecture Ch.14-26
All of the following protect the skin and mucous membranes from infection EXCEPT
HCl
Which of the following events does NOT occur in diseases transmitted by vectors?
In biological transmission, the vector multiplies in the human host.
An example of descriptive epidemiology is __________.
John Snow's study of the London cholera outbreak from 1848 to 1849
Which statement regarding the lymphatic system is true?
Lymphatic capillaries possess one-way valves. These valves permit the uptake of fluid from the body but do not allow the fluid to flow back out of the capillaries into the intracellular spaces.
A commensal bacterium
May be an opportunistic pathogen
Which of the following is NOT a reservoir of infection?
None of the answers is correct; all of these can be reservoirs of infection
Germ-free (gnotobiotic) animals often are more susceptible to infections and serious disease than are animals with a typical complement of normal microbiota. Based on this observation, which of the following would be an appropriate conclusion?
Normal microbiota stimulate the development of the immune system.
Pseudomonas bacteria colonized the bile duct of a patient following his liver transplant surgery. This is an example of a
Nosocomial infection
In mice, the LD50 for staphylococcal enterotoxin is 1350 ng/kg, and the LD50 for Shiga toxin is 250 ng/kg. Which of the following statements is true?
Shiga toxin is more lethal than staphylococcal enterotoxin.
Which of these events is an example of contact transmission?
A person drinks from a cup used by another individual.
Which of the following would be an example of disease transmission via indirect contact?
A student sneezes on her test booklet. The instructor grades it and catches her cold.
Which of the following is NOT a membrane-disrupting toxin?
A-B toxin
Which of the following can contribute to postoperative infections?
All of the answers are correct
Which one of the following is NOT a zoonosis?
All of these are zoonoses
Which of the following would be an example of an infection initiated via the parenteral route?
An individual contracts hepatitis B from an accidental stick with a contaminated needle
During a six-month period, 239 cases of pneumonia occurred in a town of 300 people. A clinical case was defined as fever 39°C lasting >2 days with three or more symptoms (i.e., chills, sweats, severe headache, cough, aching muscles/joints, fatigue, or feeling ill). A laboratory-confirmed case was defined as a positive result for antibodies against Coxiella burnetii. Before the outbreak, 2000 sheep were kept northwest of the town. Of the 20 sheep tested from the flock, 15 were positive for C. burnetii antibodies. Wind blew from the northwest, and rainfall was 0.5 cm compared with 7 to 10 cm during each of the previous three years. The etiologic agent of the disease in the situation is
Coxiella burnetii.
Which of the following is an example of the symbiotic relationship known as mutualism?
E. coli within the large intestine
Emergence of infectious diseases can be attributed to all of the following EXCEPT
The emergence of infectious diseases can be attributed to all of these.
Which of the following is NOT necessary to satisfy Koch's postulates?
The organism must cause disease through toxin production.
Koch's postulates established criteria for proving that a specific organism causes a specific disease. Which of the following is NOT one of the criteria given by Koch's postulates?
The pathogen must be isolated from inoculated animals and must be different from the original organism.
Which of the following statements about the development of infectious diseases is correct?
The period of convalescence is the time during which the person regains health and fully recovers (back to the pre-disease state).
Which of the following statements about fixed macrophages is FALSE?
They develop from neutrophils
Which of the following toxins and descriptions do NOT match?
Vibrio enterotoxin: a superantigen that destroys epithelial cells
In response to the presence of endotoxin, phagocytes secrete tumor necrosis factor. This causes
a decrease in blood pressure
Which of the following is a fomite?
a hypodermic needle
A nosocomial infection is
acquired during the course of hospitalization
The fimbriae of Neisseria gonorrhea and enteropathogenic E. coli are examples of
adhesins and ligands
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
antigenic variation
Symptoms of disease differ from signs of disease in that symptoms
are changes felt by the patient
Transient microbiota differ from normal microbiota in that transient microbiota
are present for a relatively short time
The presence of bacteria in the bloodstream is referred to as __________.
bacteremia
In a healthy human, resident microorganisms would be found in all of the following areas EXCEPT the __________.
bloodstream
Botulism is caused by ingestion of a proteinaceous exotoxin; therefore, it can easily be prevented by
boiling food prior to consumption
Which of the following diseases is NOT spread by droplet infection?
botulism
Which of the following does NOT contribute to the symptoms of a fungal disease?
cell walls
Which disease would be potentially propagated in an environment without functional plumbing and in which drinking water is contaminated with sewage?
cholera
Women who have a healthy population of Lactobacillus spp. as part of the normal vaginal microbiota are less likely to get yeast infections. Which of the following terms is used to explain this observation?
competitive exclusion
After ingesting a pathogen, lysosomal enzymes produce all of the following EXCEPT
complement
Superantigens produce intense immune responses by stimulating lymphocytes to produce
cytokines
the table 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
decreases the risk of staphylococcal infection.
Malaria is an infectious disease caused by infection with a protozoan. In certain tropical regions, malaria is constantly present. We would say that malaria is a(n) __________ disease in these regions.
endemic
Patients developed inflammation a few hours following eye surgery. Instruments and solutions were sterile, and the Limulus assay was positive. The patients' inflammation was due to
endotoxin
If one is examining a blood smear from a patient with a parasitic worm infection, which of the following leukocytes would be found in increased numbers?
eosinophils
Which of the following is involved in resistance to parasitic helminths?
eosinophils
The graph in the figure shows the incidence of polio in the United States. The period between 1945 and 1955 indicates a(n)
epidemic level
The science that deals with when diseases occur and how they are transmitted is called
epidemiology
All of the following are effects of histamine EXCEPT
fever
Which type of bacterial enzyme helps spread Streptococcus pyogenes by digesting blood clots?
fibrinolysin
The swelling associated with inflammation decreases when the fluid
goes into lymph capillaries
Which one of the following does NOT contribute to the incidence of nosocomial infections?
gram-negative cell walls
Which of the following is an effect of opsonization?
increased adherence of phagocytes to microorganisms
One effect of washing regularly with antibacterial agents is the removal of normal microbiota. This can result in
increased susceptibility to disease.
In which of the following patterns of disease does the patient experience no signs or symptoms?
incubation and convalescence
Which of these disease stages is most likely to be altered in length if the number of infecting organisms at the start of the infection is very high?
incubation period
An infection transmitted by a handkerchief or tissue is transmitted by __________.
indirect contact
A needlestick is an example of
indirect contact transmission by fomite
Which of the following mechanisms is used by gram-negative bacteria to cross the blood-brain barrier?
inducing TNF
Siderophores are bacterial proteins that compete with the host's
iron-transport proteins.
Innate immunity
is nonspecific and present at birth.
A disease in which the causative agent remains inactive for a time before producing symptoms is referred to as
latent
Focal infections initially start out as
local infections.
All of the following are methods of avoiding host antibodies EXCEPT
membrane-disrupting toxins
Which of the following is NOT an example of microbial antagonism (also known as competitive exclusion)?
microbes producing vitamins and growth factors that can be utilized by the host
The major significance of Robert Koch's work is that
microorganisms cause disease
Which non-specific defense mechanism is mismatched with its associated body structure or body fluid?
mucociliary escalator intestines
The most frequently used portal of entry for pathogens is the
mucous membranes of the respiratory tract
Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use?
mucous membranes only
In the human intestinal tract, E. coli produces vitamins beneficial to the host and can inhibit pathogen growth. In turn, the bacterium is supplied with nutrients and an environment for growth. This symbiotic relationship between E. coli and its host is an example of __________.
mutualism
Following coronary artery bypass surgery, seven patients develop Rhodococcus bronchialis infections. Cultures of the operating rooms, Nurse A, and Nurse B are taken. R. bronchialis grows from the hand and nasal swabs of Nurse A. The patients' infections are an example of a/an __________.
nosocomial infection
Health care professionals who fail to use aseptic techniques can cause __________.
nosocomial infections
Which of the following contributes to the virulence of a pathogen?
numbers of microorganisms that gain access to a host, evasion of host defenses, and toxin production
Which of the following is the third stage of a disease?
period of illness
A child falls and suffers a deep cut on her leg. The cut went through her skin and she is bleeding. Which of the following defense mechanisms will participate in eliminating contaminating microbes?
phagocytosis in the inflammatory response
Cholera toxin polypeptide A binds to surface gangliosides on target cells. If the gangliosides were removed,
polypeptide B would not be able to enter the cells.
Ingesting lactic acid bacteria to prevent colonization by intestinal pathogens such as Salmonella enterica during antibiotic therapy is an example of __________.
probiotics
Neutrophils with defective lysosomes are unable to
produce toxic oxygen products
Which of the following cytopathic effects is cytocidal?
release of enzymes from lysosomes
The occurrence of streptococcal bronchopneumonia in an individual recovering from influenza is an example of a __________.
secondary infection
Endotoxins in sterile injectable drugs could cause
septic shock symptoms
Bacteria that cause periodontal disease have adhesins for receptors on streptococci that colonize on teeth. This indicates that
streptococcal colonization is necessary for periodontal disease.
Symptoms of intense inflammation and shock occur in some gram-positive bacterial infections due to
superantigens
Infections in which the pathogen is distributed throughout the body are referred to as generalized infections or __________.
systemic infections
Which of the following is NOT a communicable disease?
tetanus
Which of these diseases does not have a human reservoir?
tetanus
The ID50 is
the dose that will cause an infection in 50 percent of the test population.
The morbidity rate is best defined as __________.
the number of individuals, relative to the population, affected by a particular disease in a period of time
A differential cell count is used to determine each of the following EXCEPT
the number of red blood cells
All of the following are true regarding NK cells EXCEPT
they destroy infected body cells by phagocytosis
Normal microbiota provide protection from infection in each of the following ways EXCEPT
they produce lysozyme.
Symptoms of protozoan and helminthic diseases are due to
tissue damage due to growth of the parasite on the tissues, waste products excreted by the parasite, and products released from damaged tissues
In which of the following cases would the Limulus amebocyte lysate (LAL) assay be used?
to ensure that a sterilized medical device is free of endotoxin
Nonpathogenic Vibrio cholerae can acquire the cholera toxin gene by
transduction
In which of the following diseases can gender be considered a viable predisposing factor?
urinary tract infections
The rise in herd immunity amongst a population can be directly attributed to
vaccinations
Cytopathic effects are changes in host cells due to
viral infections
As a health care worker, you are keenly aware of how important it is to avoid harming patients. You worry about inadvertently transmitting an infectious disease to an already compromised individual. According to the CDC, what is the most important thing you can do to avoid this?
wash my hands before interacting with any patient
