Microbiology Ch. 14
During his research on West Nile virus, Bill learned that this virus is placed within a functional grouping known as arboviruses. What is meant by the term arbovirus?
An arbovirus is an arthropod-borne virus and is maintained in nature through biological transmission.
How might a patient who is not being treated with an antibiotic still be exposed to an antibiotic?
Antibiotics can be used in aerosols, thereby entering the environment.
pathogen
have special properties that allow them to invade the human body or produce toxins
Koch's postulates are a set of guidelines to follow if you want to __________.
prove that a specific infectious disease is caused by a specific microorganism - framework for study of etiology of any infectious disease
symbiosis
relationship between two organisms in which at least one organism is dependent on the other.
In which disease 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.
Ehrlichiosis is transmitted by ticks. This is an example of __________.
vector transmission - Arthropods (such as ticks) are the most important group of disease vectors—animals that carry pathogens from one host to another.
What is the difference between normal and transient microbiota?
Normal microbiota are permanently present. - transient microbiota, may be present for several days, weeks, or months and then disappear.
Which of the following characteristics of a catheter should be considered, to help minimize the spread of nosocomial infections? a. Long b. Washable c. Inexpensive d. Reusable e. Single-use
Single-use
compromised host
an individual whose resistance to infection is impaired by disease, therapy, or burns
In which of the following patterns of disease does the patient experience no signs or symptoms?
both incubation and convalescence
which body site previously thought to be microbe free harbor some normal microbiota?
breast milk
Which of the following would be an example of disease transmission via indirect contact? a. A restaurant worker has diarrhea caused by Norovirus. b. He fails to wash his hands adequately before preparing the salad, and his customers get sick. c. A student sneezes on her test booklet. The instructor grades it and catches her cold.Mr. Smith sneezes on an airplane, and the person sitting beside him catches his cold. d. A tick that is infected with Lyme disease bites a hiker, and the hiker gets Lyme disease.
c. A student sneezes on her test booklet. The instructor grades it and catches her cold.Mr. Smith sneezes on an airplane, and the person sitting beside him catches his cold.
Which of the following statements concerning pathology, infection, and disease is true? a. Microorganisms that make up the normal microbiota of an individual never cause disease. b. The term infection is synonymous with the term disease. c. Pathology refers to the study of structural and functional changes that occur in the body as a result of a disease. d. The majority of microorganisms are pathogenic.
c. Pathology refers to the study of structural and functional changes that occur in the body as a result of a disease.
Which of the following definitions is INCORRECT? a. inapparent: infection characteristic of a carrier state b. chronic: a disease that develops slowly and lasts for months c. secondary infection: a long-lasting illness d. acute: a short-lasting primary infection e. primary infection: an initial illness
c. secondary infection: a long-lasting illness
true (1 degree) pathogens
capable of causing disease in people with normal immune sys
John Snow analyzed information about cholera victims, including where the victims lived and where they got water. This is an example of __________.
descriptive epidemiology = describes the occurrence of the disease under study - Relevant information usually includes information about the affected individuals and the place and period in which the disease occurred
endemic disease
disease constantly present in a population ex: common cold
acute
disease develop rapidly and lasts for short time ex: influenza
chronic
disease develops slowly; lasts or recurs for long periods ex: tuberculosis and hep B
noncommunicable disease
disease not spread from one host to another - caused by opportunistic microbes and microbes outside body enter via abrasions/wounds
communicable disease
disease which an infected person transmits an infectious agent either directly or indirectly to another person who then gets infected Ex: contagious = highly communicable
latent
disease with period of no symptoms when causative agent is inactivated ex: shingles caused by HHV-3
reportable disease
diseases considered to be of great public health importance.
Zoonoses
diseases that affect wild and domestic animals and can be transmitted to humans.
opportunistic pathogens (2nd degree)
don't cause disease in normal habitat in healthy person but may in a diff environment - mutualistic relationship becomes parasitic - poor/no horizontal spread - suppressed immune sys; healthy carrier of pathogenic organisms ex: E. coli harmless in large intestine but may cause infection if it gains access to urinary bladder (UTI)
Which of the following can contribute to postoperative infections? a. using syringes more than once b. errors in aseptic technique c. antibiotic resistance d. normal microbiota on the operating room staff e. All of the answers are correct.
e. All of the answers are correct.
Which of the following is NOT a predisposing factor of disease? a. occupation b. genetic background c. lifestyle d. climate e. All of these are predisposing factors of disease.
e. All of these are predisposing factors of disease.
Which one of the following is NOT a zoonosis? a. Hantavirus pulmonary syndrome b. rabies c. cat-scratch disease d. tapeworm e. All of these are zoonoses.
e. All of these are zoonoses.
Which of the following statements is TRUE? a. A parasite is not in symbiosis with its host. b. Both members are harmed in a symbiotic relationship. c. Members of a symbiotic relationship cannot live without each other. d. Symbiosis always refers to different organisms living together and benefiting from each other. e. At least one member must benefit in a symbiotic relationship.
e. At least one member must benefit in a symbiotic relationship.
Which of the following is NOT a reservoir of infection? a. a hospital b. a sick animal c. a sick person d. a healthy person e. None of the answers is correct; all of these can be reservoirs of infection.
e. None of the answers is correct; all of these can be reservoirs of infection.
Emergence of infectious diseases can be attributed to all of the following EXCEPT a. new strains of previously known agents. b. antibiotic resistance. c. climatic changes. d. ease of travel. e. The emergence of infectious diseases can be attributed to all of these.
e. The emergence of infectious diseases can be attributed to all of these.
septicemia
growth of microbes in blood = blood poisoning
Differentiate infection and disease
- Infection refers to the colonization of the body by a microorganism. - Disease is any change from a state of health. A disease may, but does not always, result from infection.
Differentiate communicable disease and noncommunicable disease
- A communicable disease is a disease that is spread from one host to another - a noncommunicable disease is not transmitted from one host to another.
Distinguish symptoms from signs as signals of disease.
- Changes in body function that the patient feels are called symptoms. Symptoms such as weakness or pain are not measurable by a physician; subjective Ex: pain and feeling of discomfort - Objective changes that the physician can observe and measure are called signs. Ex: lesions, swelling
Differentiate commensalism, mutualism, and parasitism, and give an example of each.
- Commensalism—one of the organisms benefits and the other is unaffected; e.g., corynebacteria living on the surface of the eye. or S. epidermis on skin - Mutualism—both organisms benefit; e.g., E. coli receives nutrients and a constant temperature in the large intestine and produces vitamin K and certain B vitamins that are useful for the human host. - Parasitism—one organism benefits while the other is harmed; e.g., Salmonella enterica receives nutrients and warmth in the large intestine, and the human host experiences gastroenteritis or typhoid fever.
Ten years before Robert Koch published his work on anthrax, Anton De Bary showed that potato blight was caused by the alga Phytophthora infestans. Why do you suppose we use Koch's postulates instead of something called "De Bary's postulates"?
- De Bary proved the role of fungus in the potato blight. He led many scientists to observe diseased plants and description about the association of fungi with them - Koch's postulates were used to determine the cause of a disease including plants: 1) same pathogen must be present in every case of disease 2) pathogen must be isolated from the diseased host and grown in pure culture 3) pathogen from pure culture must cause the disease 4) pathogen must be isolated from inoculated animal and shown to be the original organism
Differentiate etiology and pathogenesis
- Etiology is the study of the cause of a disease - pathogenesis is the manner in which the disease develops.
Among hospital patients who have infections, one-third did not enter the hospital with the infection but rather acquired it in the hospital. How do they acquire these infections? What is the method of transmission of these infections? What is the reservoir of infection?
- Hospital patients may be in a weakened condition and therefore predisposed to infection. - Pathogenic microorganisms are generally transmitted to patients by contact and airborne transmission. - The reservoirs of infection are the hospital staff, visitors, and other patients.
Why are some organisms that constitute the normal microbiota described as commensals, whereas others are described as mutualistic?
- Mutualistic microorganisms are providing a chemical or environment that is essential for the host. - Commensal organisms are not essential; another microorganism might serve the function as well.
focal infection
- agents of local infections enter a blood or lymphatic vessels and spread to other specific parts of body where they are confined to specific areas of body ex: teeth, tonsils, sinuses = spread to some other organ or structure of body
graph of incidence of polio - can we conclude that polio has been eradicated globally? Why or why not?
- epidemic level = between 1945-1955 - No, because the graph only depicts incidence of polio in the United States.
Put the following in the correct order to describe the pattern of disease: period of convalescence, prodromal period, period of decline, incubation period, period of illness.
1) Incubation period 2) prodromal period: ex - general aches 3) period of illness: ex - fever, chills 4) period of decline (may be crisis): ex - fever decreases 5) period of convalescence: ex - regain strength
Mycobacterium avium-intracellulare is prevalent in AIDS patients. In an effort to determine the source of this infection, hospital water systems were sampled. The water contained chlorine. Percentage of Samples with M. avium: 1) In February: Hot water (88%) & Cold water (22%) 2) In June: Hot water (50%) & Cold water (11%) What is the usual method of transmission for Mycobacterium? What is a probable source of infection in hospitals? How can such healthcare-associated infections be prevented?
1) Transmission is through inhalation, ingestion, or inoculation via the respiratory or gastrointestinal tract. Household or close contacts of those with MAC disease do not appear to be at increased risk of disease, and person-to-person transmission is unlikely. 2) Probable sources that the hospital water system has contaminated: shower heads, tubs, sinks, etc. where water can be aerosolized and inhaled 3) Can be prevented by cleaning and disinfecting all sources of water.
modification of Koch's postulates
1) etiology for viruses and bacteria that can't be grown on artificial media ex: treponema pallidum 2) some diseases caused by a variety of microbes ex: pneumonia 3) some pathogens cause several diff diseases ex: S. pyogenes 4) certain pathogens cause disease in humans only ex: HIV
Three days before a nurse developed meningococcemia, she assisted with intubation of a patient with a Neisseria meningitidis infection. Of the 24 medical personnel involved, only this nurse became ill. The nurse recalled that she was exposed to nasopharyngeal secretions and did not receive antibiotic prophylaxis. What two mistakes did the nurse make? How is meningitis transmitted?
1) exposed to nasopharyngeal secretions 2) did not receive antibiotic prophylaxis - Meningitis can be spread via nose and throat secretions (coughing, sneezing, and kissing). However, meningitis is not considered to be a highly contagious disease and casual contact or breathing in the air where a person with meningitis has been normally would not expose someone to meningitis because the causative organisms cannot live outside the body for very long. There's both acute and subacute meningitis
reasons for emerging infectious disease (EIDs) (6)
1) natural genetic recombination: E. coli 2) evolution of new strains: V. cholerae 139 3) inappropriate use of ABx and pesticides: Abx resistant strins 4) change in weather patterns: Hantavirus 5) modern transportation: West nile virus 6) ecological disaster, war, and expanding human settlement: valley fever
Which of the following diseases does NOT share a commonality with the others? A. All of the listed diseases share a commonality. B. Rabies C. Brucella D. Yersinia pestis E. Hantavirus
A. All of the listed diseases share a commonality. - all considered zoonoses - Rabies = dogs, bats; Hantavirus = rodents; Brucella = domestic lifestock; Yersinia pestis = rodents
Which one of these diseases is NOT communicable? A. Botulism B. Streptococcal sore throat C. HIV D. Influenza
A. Botulism - a noncommunicable diseases caused by microorganisms that normally grow outside the human body and are not transmitted from one host to another.
Which of the following body sites typically does NOT have normal microbiota? A. Nasopharynx B. Kidney C. Skin D. Vagina
B. Kidney
Which of the following pathogens does NOT belong with the others? A. Yersinia pestis B. Measles virus C. Hantavirus D. Brucella
B. Measles virus - Hantavirus, Brucella, and Yersinia pestis cause zoonotic diseases.
Which of the following is the third stage of a disease? A. Period of decline B. Period of illness C. Prodromal period D. Period of convalescence E. Incubation period
B. Period of illness - the disease is most severe
Which of the following is part of a plan established by the CDC, NIH, and WHO to address and prioritize issues relating to EIDs? A. Establish plans to monitor and control EIDs worldwide B. These are all part of the plan related to EIDs. C. Detect infectious pathogens, the diseases they cause, and factors that influence their emergence D. Enhance the communication of public health information and the prompt implementation of prevention strategies regarding EIDs E. Expand basic and applied research on ecological and environmental factors that influence EIDs
B. These are all part of the plan related to EIDs.
What type of nosocomial infection is likely to arise from intravenous catheterizations?
Bacteremia
Which of these events is an example of contact transmission? A. Several people become infected with Listeria after consuming contaminated ice cream. B. Tuberculosis is spread from one person to another after traveling through the air for several meters. C. A person drinking from a cup used by another individual. D. A person develops plague from a flea bite. E. Vacationers develop shigellosis, caused by the intestinal pathogen Shigella spp. after drinking contaminated water.
C. A person drinking from a cup used by another individual.
In a healthy human, resident microorganisms would be found in all of the following areas EXCEPT the __________. A. nasal passages B. tooth and gum surfaces C. bloodstream D. conjunctiva E. lower urethra
C. bloodstream
Which of the following events does NOT occur in diseases transmitted by vectors? A. In biological transmission, a vector transmits pathogens by defecating while taking a blood meal. B. In biological transmission, vectors can spread pathogens by vomiting. C. In biological transmission, the vector multiplies in the human host. D. In biological transmission, pathogens multiply in the vector, which can transmit the pathogens by injecting saliva directly into the host. E. In mechanical transmission, insects contact feces containing pathogenic bacteria and transfer it to food.
C. In biological transmission, the vector multiplies in the human host. - The pathogens reproduce in the vector, and the increase in the number of pathogens increases the possibility that they will be transmitted to another host.
An example of descriptive epidemiology is __________. A. Florence Nightingale's studies of disease transmission in soldiers and civilians during the Crimean War B. a study comparing disease rates in vaccinated and unvaccinated individuals C. John Snow's study of the London cholera outbreak from 1848 to 1849 D. the first report of a disease occurrence a comparison of drug effectiveness in two groups of patients
C. John Snow's study of the London cholera outbreak from 1848 to 1849 - Descriptive epidemiology entails collecting all data that describe the occurrence of the disease under study, has info about affected individs, place and period which the disease occurred
Which of the following is NOT an example of microbial antagonism (also known as competitive exclusion)? A. Microbes competing with other microbes for nutrients B. Microbes producing acidic compounds that limit the growth of many bacteria C. Microbes producing vitamins and growth factors that can be utilized by the host D. Microbes producing compounds inhibitory to other microbes E. Microbes utilizing oxygen necessary for the growth of other microbes
C. Microbes producing vitamins and growth factors that can be utilized by the host = mutualism - microbial antagonism = normal microbiota can benefit the host by preventing the overgrowth of harmful microorganisms = competition among microbes - conseq of microbial antagonism = normal microbiota protect host against colonization by pathogenic microbes by competing for nutrients, making harmful substance and affecting conditions like pH and O2
Which of the following is NOT necessary to satisfy Koch's postulates? A. The organism must cause the disease when introduced from pure culture into a healthy host. B. The organism must be grown in pure culture outside the diseased host. C. The organism must cause disease through toxin production. D. The organism must be re-isolated from the experimentally infected diseased animal and shown to be identical to the original isolate. E. The organism must be present in every case of the disease.
C. The organism must cause disease through toxin production.
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 = microbial antagonism = normal microbiota benefit the host by preventing overgrowth of harmful microorganisms ex: normal microbiota in vagina maintains a local pH 4. the presence of normal microbiota inhibits the overgrowth of the yeast Candida albicans which grows when there is an inbalance bt the normal microbiota and pathogens
What are the major categories of transmission of disease?
Contact, vehicle, and vector transmission
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 NOT a predisposing factor of disease? A. Occupation B. Gender C. Climate D. All of the listed choices can be predisposing factors of disease. E. Lifestyle
D. All of the listed choices can be predisposing factors of disease. - predisposing factor: is one that makes the body more susceptible to disease or alters the course of a disease
Which of the following is NOT a notifiable infectious disease? A. Salmonellosis B. Botulism C. Pertussis D. Pneumonia
D. Pneumonia
Which of these diseases does not have a human reservoir? A. Candida albicans B. Diphtheria C. Gonorrhea D. HIV E. Tetanus
E. Tetanus - 2 major nonliving reservoirs of infectious disease = soil and water - soil harbors pathogens like Clostridium tetani which causes tetanus
Which of the following is NOT considered an EID? A. Chikungunya B. Avian influenza C. West Nile Encephalitis D. Methicillin-resistant Staphylococcus aureus E. These are all considered EIDs.
E. These are all considered EIDs.
The brain tissue of the birds indicated the possibility of encephalitis. What is encephalitis, and why should this type of infection cause concern among health care professionals?
Encephalitis is an inflammation of the brain tissue. It is a concern to health care professionals because an infection in the brain means the virus has breached protective measures.
This microbe is acquired by humans as infants and is essential for good health. Acquiring a closely related strain causes severe stomach cramps, bloody diarrhea, and vomiting. What is the microbe?
Escherichia coli
Which disease stage 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 - interval between the initial infection and the first appearance of signs and symptoms
Emergence of infectious diseases can be caused by a variety of factors. Which factor listed below is related to human behavior? A. Earthquakes B. Mutations in microbes C. Lack of vaccination D. Floods
Lack of vaccination = human behavior - EIDs can result from the use of antibiotics and pesticides, climatic changes, travel, the lack of vaccinations, and improved case reporting.
What is the best mode of controlling the spread of West Nile infections?
Limit exposure to mosquitoes to prevent the transmission of West Nile virus.
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. - germ-free animals show that microbes aren't essential to animal life but these animals have undeveloped immune systems and are unusually susceptible to infection and serious disease = normal microbiota stimulate the development of IS
On October 29, Barbara participated in a study group for her microbiology class. On November 1, Barbara had a "scratchy throat" when she swallowed. On November 2, Barbara had a headache, runny nose, and watery eyes. She was fully recovered on November 7. During which time was Barbara in the prodromal period?
Nov 1 - prodromal period = appearance of first mild signs and symptoms
__________ pathogens are those that do NOT cause disease in their normal habitat but may do so in a different environment.
Opportunistic pathogens do not cause disease under normal conditions but cause disease under special conditions.
How can health care workers reduce the occurrence of nosocomial infections?
Practice more stringent aseptic techniques
A short period early in a disease that may manifest with malaise and achiness is
Prodrome
P. aeruginosa and other gram-negative bacteria tend to be difficult to control with antibiotics because of their __________, which carry genes that determine resistance to antibiotics.
R factors - These strains become part of the microbiota of patients and hospital personnel and become progressively more resistant to antibiotic therapy.
The fungus Coccidioides immitis is found in the soil. Humans contract coccidioidomycosis by inhaling fungal spores. What is the role of soil in transmission of coccidioidomycosis?
Soil is the reservoir - reservoir of infection: provides a pathogen with adequate conditions for survival and multiplication and an opportunity for transmission - can be human, animal or nonliving
Which type of nosocomial infection is the most common?
Surgical site infections
Define symbiosis
Symbiosis refers to unlike organisms living together.
In the sixth segment of the animation, why is the disease epidemic in North America?
The disease occurs at a higher rate than what would normally be expected in this region.
Which is an example of vehicle disease transmission?
The presence of Listeria on undercooked chicken served for dinner
Which of the following best defines the term pathology?
The structural and functional changes in an individual that are brought about by disease - study of disease: cause, development and effects
If mosquitoes are the mode of transmission for West Nile virus, why did the students in Bill's virology class focus on finding the virus in the dead birds rather than collecting mosquitoes to examine?
The students tried to isolate and identify West Nile virus from birds because they are an amplifying host for the virus, making it more likely that the virus can be isolated from these animals.
Expected prevalence of a disease is
the expected occurrence of a disease based on past observations.
Why are invasive procedures likely to increase the risk of nosocomial infections?
These procedures allow microbes from the skin to enter the bloodstream of the patient.
Consider the following five infectious diseases: Ebola hemorrhagic fever avian influenza SARS West Nile encephalitis mad cow disease What do these diseases have in common?
They are all emerging infectious diseases. - can result from the use of antibiotics and pesticides, climatic changes, travel, the lack of vaccinations, and improved case reporting
How can surgeons help to limit nosocomial infections?
They should perform surgeries and invasive procedures only when absolutely necessary.
What is the role of epidemiology?
To learn how to treat and prevent various diseases.
A burn patient is one example of a compromised host. (T/F)
True
A host is not considered diseased until an infection changes one's state of health. (T/F)
True
For a particular disease at a specific time period, morbidity rates should always be equal or greater than mortality rates. (T/F)
True
How can a local infection become a systemic infection?
When microorganisms causing a local infection enter a blood or lymph vessel and are spread throughout the body, a systemic infection can result.
Would you expect the epidemic and endemic graph to change if this was for the southern hemisphere, rather than the northern hemisphere? If so, how?
Yes, because the seasons are reversed in the southern hemisphere. While weather doesn't directly cause influenza outbreaks, the cold, dry air and human crowding indoors contribute to increased cases. The southern hemisphere would still have a peak, but it would be at a different time of year than the northern hemisphere.
All members of the seven families for whom Mary Mallon prepared meals developed typhoid fever. Mary did not get sick. This is an example of __________.
a carrier - living reservoirs of infection. - Some have inapparent infections for which no signs or symptoms are ever exhibited. - those with latent diseases, carry a disease during its symptom-free stages - during the incubation period (before symptoms appear) or during the convalescent period (recovery).
Two patients developed endophthalmitis (infection of the internal layers of the eye) within 24 hours of corneal transplant surgery. Streptococcus pneumoniae was isolated from conjunctival swabs of the affected eyes of both patients and from the supply of packing that was used to cover the eyes after surgery. This is an example of __________.
a nosocomial infection - infections patients acquire while receiving treatment for other conditions at a health care facility, such as a nursing home, hospital, same-day surgery center, outpatient clinic, or in-home health care environment
syndrome
a specific group of signs and symptoms that accompany a disease - diagnose disease with signs and symptoms and lab test results
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 situation is an example of
a zoonosis.
Which of the following would be considered a vector? a. A fly carrying disease from fecal matter to food b. Water droplets that come from a sneeze from an infected individual c. Water containing bacteria from fecal matter d. Saliva that is transmitted between individuals during kissing
a. A fly carrying disease from fecal matter to food
Indicate whether each of the following conditions is typical of subacute, chronic, or acute infections. a. The patient experiences a rapid onset of malaise; symptoms last 5 days. b. The patient experiences cough and breathing difficulty for months. c. The patient has no apparent symptoms and is a known carrier.
a. Acute b. Chronic c. Subacute
Which of the following would be considered a fomite? a. An infected toy b. A fly c. Contaminated water d. A tick
a. An infected toy
Which of the following statements is false? a. E. coli never causes disease. b. E. coli provides vitamin K for its host. c. E. coli often exists in a mutualistic relationship with humans. d. A disease-causing strain of E. coli causes bloody diarrhea.
a. E. coli never causes disease.
Which of the following statements about biological transmission is FALSE? a. Houseflies are an important vector. b. The pathogen may require the vector as a host. c. The pathogen reproduces in the vector. d. The pathogen may be injected by the bite of the vector. e. The pathogen may enter the host in the vector's feces.
a. Houseflies are an important vector.
On September 6, a 6-year-old boy experienced fever, chills, and vomiting. On September 7, he was hospitalized with diarrhea and swollen lymph nodes under both arms. On September 3, the boy had been scratched and bitten by a cat. The cat was found dead on September 5, and Yersinia pestis was isolated from the cat. Chloramphenicol was administered to the boy from September 7, when Y. pestis was isolated from him. On September 17, the boy's temperature returned to normal; and on September 22, he was released from the hospital. a. When is the incubation period? b. When is the prodromal period?
a. September 3-5 b. September 6-7
Which of the following statements is FALSE? a. The M in MRSA stands for mannitol. b. S. aureus is differentiated from other mannitol+ cocci by the coagulase test. c. Antimicrobial therapy for hemodialysis-associated infections increases antibiotic resistance. d. The USA300 strain accounts for most community-acquired MRSA. e. The USA100 strain accounts for most hospital-acquired MRSA.
a. The M in MRSA stands for mannitol.
What features of West Nile virus make it an emerging disease of special concern? a. West Nile virus is an arthropod-borne virus transmitted by mosquitoes. b. West Nile virus has a high mortality rate in immunosuppressed humans and infects many species of birds in southern Europe, the Mediterranean basin, and North America. c. West Nile virus is maintained in nature through biological transmission between susceptible hosts by blood-feeding arthropods. d. West Nile virus has a positive, single-stranded RNA genome that is 11,000 to 12,000 nucleotides long.
a. West Nile virus is an arthropod-borne virus transmitted by mosquitoes. b. West Nile virus has a high mortality rate in immunosuppressed humans and infects many species of birds in southern Europe, the Mediterranean basin, and North America. c. West Nile virus is maintained in nature through biological transmission between susceptible hosts by blood-feeding arthropods.
Which of the following is a fomite? a. a hypodermic needle b. insects c. pus d. droplets from a sneeze e. water
a. a hypodermic needle
Name the method of transmission of each of the following diseases: a. malaria b. tuberculosis c. salmonellosis
a. bite of an infective female Anopheles mosquito b. by airborne particles from one person to another c. person to person or animal to person by ingestion of organisms that were contaminated with feces from an infected animal or improperly cooked foods like eggs
The following choices list several types of diseases, along with factors that may contribute to their emergence. Which disease and associated factor do NOT match? a. emergence of avian influenza A (H5N1); use of antibiotics b. increased incidence of Lyme disease; increases in deer populations c. spread of cholera to new regions; modern travel d. increased incidence of malaria; global warming
a. emergence of avian influenza A (H5N1); use of antibiotics -Avian influenza is cause by a virus, which cannot be controlled with antibiotics.
The emergence of new infectious diseases is probably due to all of the following except: a. the need of bacteria to cause disease. b. the ability of humans to travel by air. c. changing environments (e.g., flood, drought, pollution). d. a pathogen crossing the species barrier. e. the increasing human population.
a. the need of bacteria to cause disease.
A Maryland woman was hospitalized with dehydration; Vibrio cholerae and Plesiomonas shigelloides were isolated from the patient. She had neither traveled outside the United States nor eaten raw shellfish during the preceding month. She had attended a party 2 days before her hospitalization. Two other people at the party had acute diarrheal illness and elevated levels of serum antibodies against Vibrio. Everyone at the party ate crabs and rice pudding with coconut milk. Crabs left over from this party were served at a second party. One of the 20 people at the second party had onset of mild diarrhea; specimens from 14 of these people were negative for vibriocidal antibodies. a. this is an example of? b. the etiologic agent of the disease is? c. the source of the disease was?
a. vehicle transmission b. Vibrio cholerae c. crabs
A healthcare-associated infection (traditionally known as a nosocomial infection) is
acquired during the course of hospitalization.
primary infection
acute infection causing initial illness
Florence Nightingale compared disease rates and other statistics for soldiers versus civilian populations. This is an example of __________.
analytical epidemiology - analyzes a particular disease to determine its probable cause - looks for factors that might have preceded the disease the disease is compared with another group of people who are free of the disease.
Analytical epidemiology
analyzes a particular disease to determine its probable cause
The yeast Candida albicans does NOT normally cause disease because of
antagonistic bacteria.
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.
vector transmission
arthropods carry pathogen from .one host to another (most important groups of vectors) - mechanical vectors = carries microbes to host on its body parts; passive - biological vectors = inject microbes into host, part of microbe life cycle completed in insect; active
Which of the following statements is true regarding hand washing? a. Hand washing should be done frequently by healthcare workers. b. Frequent and proper hand washing should be routinely done by patients and by healthcare workers, both prior to and after interaction. c. Hand washing should be done before and after patient interaction. d. Hand washing should be done frequently by patients.
b. Frequent and proper hand washing should be routinely done by patients and by healthcare workers, both prior to and after interaction.
Which of the following statements about healthcare-associated infections is FALSE? a. They occur in compromised patients. b. The patient was infected before hospitalization. c. They may be caused by normal microbiota. d. They may be caused by opportunists. e. They may be caused by drug-resistant bacteria.
b. The patient was infected before hospitalization.
All members of a group of ornithologists studying barn owls in the wild have had salmonellosis (Salmonella gastroenteritis). One birder is experiencing her third infection. What is the most likely source of their infections? a. The ornithologists are eating the same food. b. They are contaminating their hands while handling the owls and nests. c. One of the workers is a Salmonella carrier. d. Their drinking water is contaminated.
b. They are contaminating their hands while handling the owls and nests.
Which of the following diseases is NOT spread by droplet infection? a. diphtheria b. botulism c. measles d. the common cold e. tuberculosis
b. botulism
Which of the following definitions is INCORRECT? a. pandemic: a disease that affects a large number of people in the world in a short time b. epidemic: a disease that is constantly present across the world c. incidence: number of new cases of a disease d. endemic: a disease that is constantly present in a population e. sporadic: a disease that affects a population occasionally
b. epidemic: a disease that is constantly present across the world
Which of the following pairs is mismatched? a. syphilis - direct contact b. malaria - foodborne transmission c. influenza - droplet infection d. salmonellosis - vehicle transmission
b. malaria - foodborne transmission
Which of the following is classified as a latent disease? a. infectious mononucleosis b. shingles c. influenza d. tuberculosis
b. shingles caused by varcilla virus
Which of the following is NOT a communicable disease? a. tuberculosis b. tetanus c. malaria d. AIDS e. typhoid fever
b. tetanus
The presence of bacteria in the bloodstream is referred to as __________.
bacteremia
bacteremia
bacteria in blood
CDC
collect and analyzes epidemiological info in USA - case reporting: health care workers report specified disease to local, state, and national offices - report notifiable disease
When aerosols containing pathogens spread disease from a distance of less than one meter, it is considered
contact transmission.
experimental epidemiology
controlled experiments designed to test hypotheses are performed.
graph of endemic and epidemic levels
d = endemic level a = epidemic level c = gradual end of epidemic outbreak
Which of the following is an example of the symbiotic relationship known as mutualism? a. saprophytic b. Mycobacterium of the ear c. a tapeworm in the gastrointestinal tract of a human d. E. coli within the large intestine e. Corynebacterium on the surface of the eye
d. E. coli within the large intestine - synthesizes vitamin K and some B
Which of the following is not one of Koch's postulates? a. The same pathogen must be present in every case of the disease. b. The pathogen must be isolated and grown in pure culture from the diseased host. c. The pathogen from pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal. d. The disease must be transmitted from a diseased animal to a healthy, susceptible animal by direct contact. e. The pathogen must be isolated in pure culture from an experimentally infected lab animal.
d. The disease must be transmitted from a diseased animal to a healthy, susceptible animal by direct contact.
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? a. The pathogen isolated from a pure culture must cause the disease in a healthy lab animal. b. The pathogen must be isolated from the diseased host and grown in pure culture. c. The same pathogen must be present in every case of the disease. d. The pathogen must be isolated from inoculated animals and must be different from the original organism.
d. The pathogen must be isolated from inoculated animals and must be different from the original organism. - needs to be the SAME
Which of the following statements about the development of infectious diseases is correct? a. During the incubation period, the infected individual exhibits obvious signs of sickness. b. The prodromal period is characterized by very severe symptoms. c. The period of decline is the time when the infected individual's health rapidly deteriorates. d. The period of convalescence is the time during which the person regains health and fully recovers (back to the pre-disease state).
d. 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 best describes why West Nile Virus is considered to be an emerging infectious disease? a. West Nile virus causes an infection and death in birds such as crows and blue jays. b. West Nile virus causes a latent viral infection that can emerge later in life. c. West Nile virus was first isolated in Uganda in 1937 and has caused significant outbreaks every year since then. d. West Nile virus outbreaks have increased in number and affected areas since 1937.
d. West Nile virus outbreaks have increased in number and affected areas since 1937.
Which one of the following diseases is not correctly matched to its reservoir? a. influenza—animal b. rabies—animal c. botulism—nonliving d. anthrax—nonliving e. toxoplasmosis—cats
d. anthrax—nonliving
Which one of the following does NOT contribute to the incidence of healthcare-associated infections? a. lack of disinfecting surfaces b. lapse in aseptic techniques c. antibiotic resistance d. gram-negative cell wall e. slack of handwashing
d. gram-negative cell wall
mortality
deaths from notifiable disease
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 = constantly present in a population ex: common cold
A disease that is constantly present in a population is called a(n) __________.
endemic disease; ex: common cold
If a disease occurs at a fairly stable rate, it is said to be
endemic.
The science that deals with when diseases occur and how they are transmitted is called
epidemiology.
normal microbiota (flora)
establish permanent colonies on and inside body without disease - protects host with microbial antagonism = competitive exclusion = prevent pathogens from causing an infection = prevent pathogens from attaching - consume nutrients; chemical/physical environment created = hostile to other microbes ex: E. coli
colonization
establishment of microbe in body tissue; don't cause disease in normal condition
A cold transmitted by a facial tissue is an example of
fomite.
The protection from infection received when individuals susceptible to a particular disease live in a population where many individuals are immune is referred to as __________.
herd immunity - People who are immune to an infectious disease (due to vaccination) will not be carriers = reducing the occurrence of the disease and acting as a barrier to the spread of infectious agents = non-immune people will also be protected because of the unlikelihood of their coming into contact with an infected person.
If a prodromal period exists for a certain disease, it should occur prior to
illness
morbidity
incidence of specific notifiable diseases - # infected persons
An infection transmitted by a handkerchief or tissue is transmitted by __________.
indirect contact - occurs when the agent of disease is transmitted from its reservoir to a susceptible host by means of a nonliving object (fomite)
An infection transmitted by a hypodermic needle is transmitted by __________.
indirect contact - occurs when the agent of disease is transmitted from its reservoir to a susceptible host by means of a nonliving object.
A needlestick is an example of
indirect contact transmission by fomite.
nosocomial infection
infection patients acquire while getting treatment from: 1) microbes in hospital environment 2) weakened host immune sys 3) chain of transmission in hospital - prevent with aseptic techniques and precautions
infection
invasion and colonization of host by microorganism
Biological transmission differs from mechanical transmission in that biological transmission
involves reproduction of a pathogen in an arthropod vector prior to transmission.
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
pathogenesis
manner which disease develops
A commensal bacterium
may also be an opportunistic pathogen.
transient microbiota
microbes that are present for various periods and then disappear - dynamic nature = changes due to age, type of food consumed, hormonal state, ABx therapy - probiotics = live microbes applied/ingested to body to show a beneficial effect = restore gut microbiome
The major significance of Robert Koch's work is that
microorganisms cause disease.
polymicrobial
mixed infection ex: necrotizing fasciitis
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 = benefits both organisms ex: large intestine has E. coli that synthesize Vitamin K and B. These vitamins absorbed into bloodstream and distributed for use by body cells and in xc the large intestine use provide nutrients used by bacteria = allow survival
emerging infectious diseases (EIDs)
new or changing, showing an increase in incidence in the recent past, or a potential to increase in the near future
subclinical infection
no noticeable signs and symptoms - inapparent infection ex: poliovirus and hep A virus
how is the human microbiome acquired?
normal and characteristic microbial population establish themselves in a person before birth (in utero) - lactobacilli colonize the gut and provides enzymes for milk digestion - more microbes go into newborn from environment through contact with people, breathing and feeding - first 3 years microbiome changes rapidly = establish human microbiome - microbe acquisition on skin, oral, respiratory and gut microbes (E. coli)
Microorganisms that typically colonize a host without causing disease are referred to as the __________.
normal microbiota - microbes that colonize but don't produce disease under normal conditions - localized in certain regions
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 = healthcare-associated infections (HAIs)
Pseudomonas bacteria colonized the bile duct of a patient following his liver transplant surgery. This is an example of a
nosocomial infection.
Health care professionals who fail to use aseptic techniques can cause __________.
nosocomial infections
mortality rate
number of deaths resulting from a disease in a population in a given period of time in relation to the total population. previous
secondary infection
occurs after host is weakened from primary infection ex: pneumocytis pneumonia as conseq of AIDs
host
organism that shelters and supports growth of pathogens
animal reservoirs
pathogen for some otherspecies lives and multiplies in reservoir with 1) direct contact with animal or feces 2) contamination of food and water 3) consume infected animal product 4) insect vectors 5) zoonosis = disease transmitted to humans by wild or domestic animals ex: rabies
human reservoirs
people with disease or asymptomatic carriers may have inapparent infections (incubation/convalescent) or latent disease ex: Bordetella pertussis = transmit infection to non-vaccinated infant
During the __________, a person recovers from a disease and the body returns to its pre-disease state.
period of convalescence - people can spread infection during convalescence - ex: typhoid fever and cholera - convalescing person carries pathogenic microbes for months to years
The __________ is the time that lapses between an encounter with a pathogen and the first symptoms
period of incubation
direct contact transmission
person-to-person transmission, is the direct transmission of an agent by physical contact between its source and a susceptible host; no intermediate object is involved. - person to person and droplet spread - proximity as whenn speaking
Nationally notifiable infectious diseases
physicians are required to report the incidence of certain infectious diseases by law
In order to understand the full scope of a disease, we take its occurrence into account. The __________ of a disease is the number of people in a population who develop a disease at a specified time.
prevalence: takes into account both old and new cases. It's an indicator of how seriously and how long a disease affects a population.
case reporting
procedure that requires health care workers to report specified diseases to local, state, and national health officials
The occurrence of streptococcal bronchopneumonia in an individual recovering from influenza is an example of a __________.
secondary infection = one caused by an opportunistic pathogen after the primary infection has weakened the body's defenses. - common in skin and respiratory tract and sometimes more dangerous than the primary infections.
Koch observed Bacillus anthracis multiplying in the blood of cattle. What is the condition specifically called when bacteria are multiplying in the blood?
septicemia
The health of the patient
should be the primary concern of the healthcare worker.
nonliving reservoirs
soil, water, food - water contaminated by feces = GI disease ex: cholera - improperly prepared or stored food = Salmonella - soil has fungi = clostridium
contact transmission
spread of a disease agent by direct contact, indirect contact, or droplet transmission.
Airborne transmission
spread of agents of infection by droplet nuclei in dust that travel more than 1 meter from the reservoir to the host
systemic (generalized) infection
spread throughout body via blood/lymph ex: measles
An infection that does NOT cause any signs of disease is a(n) __________.
subclinical infection Ex Poliovirus and hepatitis A virus: can be carried by people who never develop the illness.
Infections in which the pathogen is distributed throughout the body are referred to as generalized infections or __________.
systemic infections - microbes spread throughout body by blood or lymph ex: measles
local infection
the invading microorganisms are limited to a relatively small area of the body ex: boils and abscesses
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
Incidence of a disease
the number of new cases of a disease in a given area or population during a given period of time - indicator of the spread of the disease
If a patient notices a healthcare worker not following suggested precautions,
they should immediately bring it to the attention of the healthcare worker.
sepsis
toxic inflammatory condition arising from spread of microbes or their toxins from a focus
vehicle transmission
transmission of disease agents by a medium, such as water, food, or air. - waterborne = poor water contamination - foodborne = uncooked food bc cross contamination - fecal-oral transmission
Alfalfa sprouts were responsible for transmitting Salmonella to 32 people in four states. This is an example of __________
vehicle transmission - transmission of disease agents by a medium, such as water, food, or air
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 and after interacting with any patient
sporadic disease
when a particular disease occurs occasionally ex: typhoid fever
epidemic disease
when many people in a given area acquire a certain disease in a relatively short period; widespread occurrence at given time in given area ex: influenza
indirect contact transmission
when the agent of disease is transmitted from its reservoir to a susceptible host by means of a nonliving object 1) airborne transmission = in air 2) contaminated objects 3) vector-borne diseases
Epidemiology is defined as the study of
where and when a disease occurs, and how it is transmitted.
pandemic
worldwide epidemic ex: AIDS