Microbiology Final
Which of the following conditions usually results in severe acute liver damage?
co-infection with hepatitis B and hepatitis delta viruses
Which of the following is a notable symptom of giardiasis?
foul-smelling "rotten egg" stools
which of the following methods of preserving food sterilizes it
gamma radiation
Which of the following items that are commonly added during food preparation can be considered a preservative?
garlic
Which of the following pairs of industrial microbial products and their uses is mismatched?
gluconic acid — release of cellulose from flax to make linen
Escherichia. coli O157:H7 is primarily associated with which of the following foods?
ground beef
Chancroid is caused by
haemophilus ducreyi
Schizogony is an important aspect of which of the following diseases?
malaria
Which of the following is an application of proteases?
meat tenderizer
The majority of cases of staphylococcal toxic shock syndrome occur in
menstruating women
Condylomata acuminata are associated with infections of which of the following?
papillomaviruses
Which of the following is the major sign or symptom of mumps?
parotitis
What was the first substance produced by microorganisms to be used pharmaceutically?
penicillin
What is the primary symptom of Enterobius infections?
perianal itching
Porphyromonas gingivalis is associated with
periodontitis.
The DTaP vaccine protects against which of the following respiratory diseases?
pertussis
Which of the following is part of the upper respiratory system?
pharynx
) Which of the following is the correct sequence of microbial associations from smallest to largest?
populations, guilds, communities, microhabitats, ecosystem
Diphtheria toxin kills cells by interfering with which of the following processes?
protein synthesis
which of the following is associated with candida infections
pseudohyphae
Croup is often a result of infection with which of the following?
respiratory syncytial virus
The noninfective, obligately intracellular forms of chlamydia are called
reticulate bodies
The viruses responsible for the majority of infant deaths resulting from diarrhea in the world are the
rotaviruses
Which of the following is considered an intrinsic factor for food spoilage?
storage temperature
Which of the following allows group A streptococci to spread through tissues by breaking down blood clots?
streptokinase
Which of the following is a common source of antibiotics?
streptomyces
Legionella pneumophila is an opportunistic pathogen that
survives in the environment as an intracellular parasite of a protozoan.
Diagnosis of syphilis is usually made by
the MHA-TP test.
Inhalation anthrax is frequently fatal even with antibiotic therapy because
the anthrax toxin triggers severe edema of the lungs.
Which of the following vessels carries blood from the heart to the rest of the body?
the aorta
Which of the following statements is TRUE regarding gonorrhea?
the causation agent can grow on most mucous membranes of the body
Neisseria gonorrhoeae most commonly infects which of the following in females?
the cervix
Which of the following is an organ of the gastrointestinal tract?
the esophagus
Where in the digestive tract does the absorption of water take place?
the large intestine
Which of the following terms is used to designate the area of water along the shoreline in a lake?
the littoral zone
Where in the kidney is blood initially filtered to form urine?
the nephron
Which of the following structures allows fetal blood vessels to exchange nutrients and wastes with the mother's blood vessels?
the placenta
What is the primary determinant of virulence in Streptococcus pneumoniae?
the presence of a polysaccharide capsule
Which of the following is a characteristic of bacterial vaginosis frequently used to confirm diagnosis?
the presence of clue cells
Which of the following factors is primarily responsible for the ability of Mycobacterium tuberculosis to survive long periods of time in dried droplets of respiratory aerosols?
the presence of mycolic acid in the cell wall
Blood is found in which of the following areas of the heart just before it is pumped into the lungs?
the right ventricle
The common source of contamination in the majority of cases of staphylococcal food poisoning (intoxication) is
the skin of food preparers
Select a specific example of bioremediation from the following:
the use of Pseudomonas to clean up oil spills
Food microbiology applies to
the use of microorganisms to make food and to control microbial activity to prevent foodborne illness.
The CDC reports concern about a new influenza strain designated A/Bali/2/2010 (H5N2). This nomenclature means
the virus is a type A with antigens HA 5 and NA 2 isolated in Bali in February 2010.
Which of the following describes secondary metabolites?
they are produced during the stationary phase of growth
A distinctive feature of secondary syphilis is
blister like lesions which ulcerate
Untreated infection of males with Neisseria gonorrhoeae may result in
sterility
List and describe three virulence factors associated with bacteria that cause gastroenteritis.
(1) Several types of exotoxins can cause many of the major symptoms of bacterial gastroenteritis. These include cholera toxin, which produces "rice-water" stools, enterotoxins of Escherichia coli that act in a manner similar to cholera toxin, and the more destructive Shiga toxin of Shigella and the Shiga-like toxin of Escherichia coli O157:H7. (2) Both Salmonella and Shigella have the ability to grow inside host cells, thereby evading the immune system. (3) Salmonella possesses a type III secretion system that enables it to introduce toxins directly into host cells. (4) Many pathogens such as Campylobacter possess adhesins that allow them to adhere to cells lining the gastrointestinal tract. (5) Most of the bacteria producing gastroenteritis are Gram-negative; therefore, they have endotoxin molecules in their cell walls that can serve as virulence factors.
Explain the role of the intestinal microbiota in the maintenance of health.
(1) The billions of microbes in the gastrointestinal tract outcompete pathogens in a process called microbial antagonism. (2) The normal microbiota can feed on the partially digested or indigestible contents of the colon, and even though this produces some undesirable by-products such as flatus, this is overall a beneficial process for the host. (3) Many intestinal microbes produce important vitamins for the host, such as vitamin K, B12, folic acid, and biotin.
at what age is a young female most susceptible to urinary tract infections
3 years old
Compare and contrast dengue hemorrhagic fever and Ebola hemorrhagic fever. Discuss both the pathogens and the pathology.
: Both diseases are caused by RNA viruses. Both start with fever, headache and muscle pain, then a rash develops, followed by bleeding. There is no specific treatment for either disease and no vaccines are available to prevent them. Dengue hemorrhagic fever is caused by a member of the Flaviviridae, a +ssRNA virus with an icosahedral capsid. It is transmitted by Aedes mosquitoes. A first infection with dengue virus does not lead to the hemorrhagic disease, but it is subsequent infection that produces the hemorrhagic disease. Memory T cells produced in response to the first infection are activated upon subsequent infection and release inflammatory cytokines that trigger a hyperimmune response that results in damage to blood vessels, internal bleeding, and may progress to shock from excessive blood loss. Ebola viruses are filamentous —ssRNA Filoviridae whose natural hosts are thought to be bats. Humans become infected when handling an infected animal, after which the virus can be transmitted from person to person by unprotected contact with blood and other bodily fluids. Ebola virus infection initially triggers excessive clotting which results in depletion of clotting factors, which in turn leads to extensive internal hemorrhaging. Death results from massive shock and kidney failure.
How does water quality testing make use of environmental microbiology?
: Information gained through the study of environmental microbiology has been utilized to identify many of the fecal coliforms and their biological traits and to develop methods to identify whether they are contaminating our water supplies. A simple method is to filter water through a fine membrane and then place the filter on EMB agar. Growth of fecal coliforms will produce a metallic green sheen. The colonies are counted, and the number is used to calculate the degree of contamination. Another method is to add a water sample to small bottles containing MUG and ONPG and look for evidence of fecal coliform growth indicated by the resulting color changes. This latter method is more rapid; however, it indicates only that these microorganisms are present, but does not provide information regarding the actual number of bacteria present.
Describe the various ways in which the respiratory system is protected from invasion by pathogens.
: The respiratory system has a variety of built-in defense mechanisms that prevent this highly sensitive body system from being attacked or damaged by pathogens. Hairs in the nasal cavity filter out large particles and the mucus lining the nasal cavity and sinuses trap and remove smaller particles and microbes. A primary line of defense is the collection of ciliated cells lining the mucous membranes of the nasal cavity, pharynx, trachea, bronchi, and bronchioles. The activity of these cells, often called the ciliary escalator, constantly removes the pathogens and other particles trapped in mucus before they can gain access to the deepest and most vulnerable parts of the respiratory system. Other defense mechanisms include alveolar macrophages, which protect the alveoli of the lungs from invaders that make it past the previous defenses, and secretory IgA antibodies, which are present in tears, saliva, and mucus. The upper respiratory tract also has normal microbiota that limit the access of pathogens to the area; however, under the right conditions, some of these can become opportunistic pathogens in their own right when some of the previously mentioned defense mechanisms fail.
some areas of the genitourinary tract are normally sterile, whereas other areas have a variety of microbiota. Describe the defense mechanisms of the genitourinary tract that contribute to this dichotomy.
A variety of defense mechanisms are associated with the genitourinary tract, but the primary one is the flow of urine through the urethra. This flow keeps many pathogens out, and therefore, the only microbes that can colonize this area tend to colonize the end of the urethra closest to the surface of the body. Often, pathogenic microbes can resist this flow and migrate toward the bladder and kidneys. Overall, however, the urinary organs of both sexes and the male reproductive tract above the prostate should be sterile under normal conditions. In females, microbes enter the vagina and colonize the nutrient-rich mucous membrane in this area; however, most vaginal pathogens are inhibited by the acidic pH generated by normal microbiota such as Lactobacillus.
A young man who is an avid outdoorsman goes to see his doctor complaining of fever with chills, headache, nausea, and diarrhea. Blood tests show that he has low levels of leukocytes and platelets. He may have contracted
A person reports to a clinic complaining of fever and abdominal pain. The abdomen is swollen, and blood tests indicate kidney damage. A stool sample is examined under a microscope and found to contain eggs with a spine projecting from its surface. The indications are consistent with infection with
Historically, physicians have used a procedure called xenodiagnosis to diagnose which of the following diseases?
Chagas' disease
Which of the following bacteria is commonly used to produce vinegar?
Acetobacter
Which of the following statements is TRUE regarding genital herpes?
Acyclovir is effective in reducing the occurrence of lesions, but is not a cure.
Which of the following is used to produce soy sauce?
Aspergillus oryzae and Lactobacillus
Sake is a fermentation product of
Aspergillus oryzae and Saccharomyces
Explain the necessity of producing a new vaccine for each year's flu season.
Because the genome of influenzavirus is capable of extraordinary reassortment and genetic variation, new strains of the virus constantly arise. Various strains of influenzavirus pass through a variety of animal hosts (most notably pigs, birds, and humans), resulting in the production of new combinations of genome segments. The outcome of all the genetic rearrangement is either antigenic drift, a phenomenon in which the HA and NA glycoproteins of the virus undergo minor genetic changes, or antigenic shift, in which major antigenic changes occur in the glycoproteins, resulting in virtually brand-new strains of the virus. Therefore, because the virus is undergoing constant antigenic change, U.S. health officials monitor the worldwide incidence of flu, making note of which strains seem likely to occur in the next flu season, and making adjustments to the flu vaccine accordingly.
A bull's-eye rash is associated with infections of which of the following?
Borrelia burgdorferi
Compare and contrast bubonic and pneumonic plague.
Both bubonic and pneumonic plague are caused by Yersinia pestis and are transmitted by fleas that migrate between animal hosts and humans. However, pneumonic plague is generally much more serious than bubonic plague, develops more rapidly, and is more often fatal than bubonic plague. In addition, pneumonic plague can occur when Yersinia pestis is inhaled, so it can be transmitted from person to person. Bubonic plague is transmitted only by infected fleas. Treatment and prevention of both diseases are similar: plague is easily treated by common antibiotics such as tetracycline, and prevention involves rodent and flea control, as well as good personal hygiene.
Which of the following Streptococcus pyogenes virulence factors decreases leukocyte movement into an infected area?
C5a peptidase
The most common bacterial cause of diarrhea that sends people to doctors in the United States is
Campylobacter.
Which of the following is a fungus which commonly lives in the large intestine?
Candida
Some sexually transmitted diseases mimic other STDs with regard to their symptoms; give an example of two of these types of diseases, describing how the symptoms of each disease resemble those of another STD.
Chlamydial infections in men often mimic the symptoms of gonorrhea even though the two diseases are caused by completely different pathogens with different life cycles and different pathogenic properties. In both cases, the male experiences urethritis, painful urination, and a pus discharge from the urethra. By the same token, most gonorrhea and chlamydia infections in females are asymptomatic. Occasionally, some of the signs and symptoms of trichomoniasis in men can also mimic some of the signs and symptoms of gonorrhea. Another pair of STDs that can be confused with each other is syphilis and chancroid. These diseases are caused by two completely unrelated bacteria; however, each of them is initially characterized by the appearance of a sore called a chancre. In syphilis, the chancre is painless and hard, whereas in chancroid the chancre is soft and painful (it is usually called a "soft chancre" to help distinguish it from the primary syphilis lesion).
Ornithosis, a disease of birds that can be transmitted to humans, is caused by
Chlamydophila psittaci.
There are vaccines to prevent infectious hepatitis and serum hepatitis, but none to prevent chronic hepatitis. Discuss why this is so.
Chronic hepatitis is caused by the hepatitis C virus. Hepatitis C virus is an RNA virus, and the RNA polymerase which replicates the RNA genome lacks proofreading ability. As a consequence, new genetic variations with new antigenic structures are produced at high frequency. A vaccine against a single hepatitic C antigen would not provide protection from infection for all the variations, and a vaccine containing a large number of different antigens is not practical. Hepatitis A virus is not as variable, and hepatitis B virus is a DNA virus, DNA polymerases have proofreading functions.
What member of the human intestinal microbiota occasionally causes life-threatening disease?
Clostridium difficile
A young woman being treated for serious burns develops severe diarrhea accompanied by intense abdominal pain. She passes several watery, foul-smelling, bloody stools a day. A colonoscopy reveals patches of yellowish lesions in the large intestine. The probable causative agent is
Clostridium difficile.
Which of the following statements is TRUE regarding the common cold?
Cold viruses are frequently spread by contaminated fomites.
V shapes and palisade arrangements are characteristic of which of the following?
Corynebacterium diphtheriae
The intracellular parasite usually acquired in contaminated drinking water which causes a persistent watery diarrhea is
Cryptosporidium parvum.
Diagnosis of hepatitis B infection is made by the observation of which of the following in the patient's body fluids?
Dane particles
Which of the following causes "beaver fever?"
Enterobius vermicularis
Which of the following is a common childhood parasite in the United States?
Enterobius vermicularis
Which of the following microorganisms is the most commonly used indicator organism for water quality testing?
Escherichia coli
The most common cause of traveler's diarrhea is
Escherichia coli.
Compare and contrast the two types of foodborne disease
Foodborne diseases are also known as food poisoning. Food poisoning may be due to food infections, caused by consuming living microorganisms, or to food intoxication, caused by consuming microbial toxins in food. Many cases of foodborne diseases are common-source epidemics, where one food source is responsible for many individual cases of the disease. Food infections primarily result from improper food handling or storage, whereas food intoxication may result from improper preparation, especially canning. Heating food is usually effective in killing living microbes in food, but most toxins are not inactivated by heating.
The DNA virus known as "serum hepatitis" is
HBV.
Which of the following hepatitis viruses usually produces subclinical infections?
HCV
A young man who works on a ranch and lives in the log bunkhouse experiences sudden fever with muscle aches. A few days later he begins to cough and have difficulty breathing, and goes to an urgent care clinic. A blood sample reveals a high leukocyte count and low platelets. A Gram-stain of a sputum sample shows only a few small bacteria present. Which of the following is the most likely infecting agent?
Hantavirus
Limiting exposure to rodents and their waste materials is an important means of controlling
Hantavirus pulmonary syndrome.
Urease is an important virulence factor of which of the following?
Helicobacter pylori
Which of the following is now known to be the cause of most peptic ulcers?
Helicobacter pylori
Explain how Helicobacter pylori is able to resist the unfavorable environment of the stomach in order to cause disease.
Helicobacter pylori is able to resist the acidic environment of the stomach using a variety of virulence factors. H. pylori produces a protein which inhibits acid production in the stomach, and produces urease that converts urea to ammonia, which neutralizes stomach acid. H. pylori has flagella that allow it to burrow beneath the mucous layer of the stomach lining, further sheltering the pathogen. It also produces enzymes such as catalase that inhibit phagocytic cell activity.
Which of the following statements concerning Francisella is FALSE?
Humans are its only known host.
Which of the following statements concerning the phosphorus cycle in bacteria is correct?
It involves moving the molecule from insoluble to soluble forms.
Which of the following statements concerning the biochemical oxygen demand (BOD) is correct?
It is a measurement of the amount of oxygen that aerobic bacteria require to fully metabolize organic wastes in water.
Which of the following is a means by which Borrelia burgdorferi evades the body's defenses?
It is capable of antigenic variation and has manganese-containing enzymes.
Which of the following statements concerning Toxoplasma infection is correct?
It is typically contracted by eating undercooked meat.
Which of the following statements is TRUE regarding tuberculosis?
It remains viable in dried aerosol droplets for up to eight months.
Which of the following statements is TRUE with regard to Entamoeba histolytica?
It uses pseudopodia to attach to the intestinal lining.
The designation "group A," used to help classify Streptococcus pyogenes, refers to this bacterium's
Lancefield antigen.
Which of the following is extremely fastidious in its nutrient requirements, which include iron salts and cysteine?
Legionella pneumophila
Which of the following is a lactic acid bacterium used in the production of food?
Leuconostoc
Which of the following microorganisms associated with food poisoning thrives in cold storage?
Listeria monocytogenes
xplain why a female who has a history of gonorrhea infections is more likely to have an ectopic pregnancy.
Most females infected with gonorrhea are asymptomatic and do not receive treatment. The bacterium, Neisseria gonorrhoeae, invades the cervix and the uterus, and then can hitchhike on sperm to infect the fallopian tubes. In the uterine tubes, the bacteria trigger inflammation, fever, and abdominal pain, a condition known as pelvic inflammatory disease. Chronic infections lead to scarring of the fallopian tubes, resulting in an increased chance of ectopic pregnancy and sterility.
What are the levels of microbial associations in the environment? How do they relate to an ecosystem?
Microorganisms are associated with each other at many levels in the environment. Individual growing and reproducing organisms that are all of one species are referred to as a population. Populations of microorganisms performing metabolically related processes are known as guilds. Guilds constitute communities. Guilds and populations within a community typically reside in their own habitat. Together, the organisms, the environment, and the relationship between the two constitute the ecosystem.
Describe the pathogenesis of tuberculosis, paying special attention to the characteristics of Mycobacterium tuberculosis that make it so pathogenic.
Mycobacterium tuberculosis is an extremely effective pathogen. It has a very low infectious dose (about 10 cells). Once inside the body, it is hard to clear because of its slow growth, high levels of waxy, protective lipids such as mycolic acid in its cell wall, and its ability to survive inside phagocytic cells. Another cell wall component, cord factor, is toxic to the body's cells, and inhibits the activity of neutrophils. The immune system does its best to isolate the infection, producing tubercles, which contain M. tuberculosis cells that have been walled off from the rest of the body by inflammatory cells and processes. At best, this process results in a stalemate between the pathogen and the body, and no further disease may ever occur. However, in immunocompromised individuals, the immune system is often not able to keep the pathogen in check; M. tuberculosis therefore breaks the stalemate and begins to spread throughout the lungs, causing secondary or reactivated tuberculosis, with its attendant symptoms of weight loss, chest pain, and breathing difficulty with bloody sputum. From the lungs, the reactivated mycobacterial infection may even spread to the bloodstream and all over the body in the phenomenon of disseminated tuberculosis.
Infection with which of the following species of Plasmodium is most likely to be fatal?
P. falciparum
Which of the following is considered part of the microbiota of the lower respiratory system?
Pneumocystis jiroveci
Which of the following diseases is almost diagnostic for AIDS?
Pneumocystis pneumonia
Compare and contrast pneumococcal and mycoplasmal pneumonia.
Pneumonia describes a general pathogenic process in which a bacterial or viral infection of the lungs results in their being filled with fluid, and the subsequent complications arising from such a process. Among bacterial pneumonias, both pneumococcal and mycoplasmal pneumonias are common types. Pneumococcal pneumonia is caused by Streptococcus pneumoniae, while mycoplasmal pneumonia is caused by Mycoplasma pneumoniae. In general, pneumococcal pneumonia is a more serious disease than mycoplasmal pneumonia, which is often called "walking pneumonia" because of its milder symptoms. Pneumococcal pneumonia has a more seasonal occurrence than mycoplasmal pneumonia, which is seen throughout the year. Furthermore, mycoplasmal pneumonia is seen most commonly in adolescents and young adults, whereas pneumococcal pneumonia is more common in children, the elderly, and immunocompromised patients. S. pneumoniae produce a variety of virulence factors that result in serious damage to lung tissue, even producing blood in the sputum being coughed up. The bacteria can further migrate into the bloodstream from the damaged lung tissue, sometimes even causing more serious bacteremia and meningitis. On the other hand, mycoplasmas have more limited virulence factors, and their main mode of pathogenesis is the elimination of the function of the ciliary escalator, resulting in mucus buildup that causes a persistent, unproductive cough as the patient tries to clear the lungs. Other bacteria may enter the lungs as a result of the failure of this defense mechanism, but in general, mycoplasmal pneumonia never gets severe enough to require hospitalization.
Which of the following statements is TRUE with regard to oral herpes?
Primary infections are usually characterized by severe lesions.
Which of the following is used in both food production and industrial production?
Saccharomyces cerevisiae
Microscopic identification of its spiny eggs is used in the diagnosis of infections caused by
Schistosoma.
Explain the difference between bacteremia and septicemia, and describe some of the factors that can lead to septicemia.
Septicemia is a microbial infection of the blood that causes disease. Although the terms bacteremia and septicemia are sometimes used interchangeably, bacteremia technically refers to septicemia caused by bacteria in the bloodstream. The signs and symptoms of bacteremia and septicemia are essentially the same, and both can lead to adverse consequences such as toxemia, lymphangitis, or septic shock. To be able to cause these problems, the bacteria involved in septicemia may possess capsules, have the ability to capture iron from the host's tissues, and/or release a variety of endotoxins that ultimately damage host cells and tissues.
Toxic shock-like syndrome is associated with
Streptococcus aureus.
The majority of cases of otitis media are caused by
Streptococcus pneumoniae.
The majority of cases of pneumonia are caused by
Streptococcus pneumoniae.
Which of the following is used in the production of yogurt?
Streptococcus thermophilus
Which of the following statements is TRUE regarding infection with Mycoplasma pneumoniae?
The causative agent attaches to ciliated cells in the respiratory tract.
A patient complains of fever, pain on one side of the body, and fatigue. The clinician notes that the skin is red, but the rash is not spotty. The patient reports experiencing some painful urination for a few days during the previous week. Tests on a urine sample reveal the presence of motile Gram-negative bacilli. What is the patient most likely suffering from?
The flank pain and the reddening of the skin are indicative of pyelonephritis. The Gram stain of the urine sample is consistent with that of enteric bacteria. The patient probably contracted a urinary tract infection caused by fecal contamination of the urethra. When left untreated, this infection then spreads to the kidneys. .
Why is immunity to the common cold so hard to develop, either naturally or through vaccines?
The primary reason that immunity generally does not develop against the common cold is that there is not a single cause of the disease. A variety of viruses, including rhinoviruses, coronaviruses, and adenoviruses, can cause the symptoms of the common cold. Therefore, any vaccine designed to protect against the common cold would have to include antigens from all the different viruses that can cause the disease, which is simply not practical or even feasible. The exception to this is the vaccine against adenovirus infections, although it is currently used only for military recruits. Because of the vast number of viruses that can cause the common cold, even natural immunity is hard to obtain, because a person may not encounter the exact same virus serotype twice in a lifetime. In addition, the receptor for ICAM-1on the virus particle is not accessible by antibodies, preventing antibody neutralization of the virus. However, the frequency of colds does decrease as a person ages, so some immunity undoubtedly occurs, including some herd immunity.
Which of the following statements is TRUE concerning diphtheria?
The signs and symptoms of the disease are directly caused by a bacterial toxin.
Smallpox is considered a serious potential biological weapon, whereas anthrax has been successfully used as one. Compare and contrast their potential with regard to the criteria for assessing biological threats.
The smallpox virus causes serious illness with moderate to high fatality rates. The virus is highly contagious by contact and aerosols, and it is contagious before clear signs appear. The virus can persist on fomites and infect persons who come in contact with them. Although a vaccine exists, the majority of the world's population is currently unvaccinated. Consequently, once released, the virus will spread rapidly. However, there is no natural source for the virus, so a person or persons intent on using it as a weapon would have to have special access and facilities to be able to produce much virus. Additionally, post-exposure vaccination is effective in producing immunity, so the resulting epidemic could be controlled once recognized. The agent of anthrax, Bacillus anthracis, is an animal pathogen and a common soil contaminant. The organism can be easily isolated from contaminated soil and is not difficult to culture. The disease is not transmissible from person to person, so only the people exposed to the initial release would be at risk. However, the bacterium produces endospores that can be stored for long periods of time and released as a dust contaminant in airways or contact contaminant on fomites. Public perception of anthrax is that it is a very dangerous weapon. Initial respiratory symptoms are similar to other bacterial pneumonias, so proper diagnosis may not be made until the fatal toxemia develops. The current vaccine is expensive and does not produce immunity until after several boosters have been administered; therefore, it is not useful for controlling disease after a release. Natural B. anthracis is susceptible to most antibiotics, so treatment in cases of early detection is effective. Authorities are concerned about the potential for the development of antibiotic-resistant strains.
A nursing student develops a positive reaction to the tuberculin skin test. A history reveals possible exposure to patients with tuberculosis. A sputum sample is acid-fast negative. When asked for vaccination records, the student reports that childhood vaccination records were lost when the family emigrated from a southeast Asian country. What is the best explanation for the test results?
The student has been exposed to Mycobacterium tuberculosis or was vaccinated with BCG vaccine.
How does the age of the infected individual play a role in the development of Epstein-Barr virus (HHV-4) infections such as infectious mononucleosis?
The symptoms of most Epstein-Barr infections result from a "war" between the cellular and humoral divisions of the immune system. B cells are infected by Epstein-Barr virus, and then cytotoxic T cells try to kill the infected B cells. The younger an infected individual is, the less mature his or her cellular immune system is, and the less effective it will be in causing symptoms during the "war." In fact, in young children, Epstein-Barr virus infections are usually asymptomatic. The later in life an individual is infected with Epstein-Barr virus, the more vigorous the cellular immune system is, and the more problematic and symptomatic the infection becomes. On the other hand, however, a vigorous cellular immune response also means that the infected B cells may be completely eradicated from the body, resulting in no discernible disease in many individuals.
List and compare the three types of amebiasis.
The three types of amebiasis differ in the virulence factors of the infecting strain of Entamoeba histolytica and the state of health of the host. The least severe form of amebiasis is luminal amebiasis in which the parasite remains in the open space of the intestine. Luminal amebiasis is asymptomatic in healthy individuals. When the strain of E. histolytica produces adhesion proteins, proteases, or other important virulence factors, they can invade the bloodstream and peritoneal cavity, producing the more serious forms of amebiasis. Amebic dysentery is characterized by severe diarrhea, bloody, mucus-containing stools, and colitis. Invasive extraintestinal amebiasis occurs when E. histolytica spreads to other areas of the body and forms necrotic lesions in the liver, lungs, kidneys, and other vital organs. It is the most severe form of the disease and can even be fatal.
Explain why some syphilis patients may only experience the symptoms of primary syphilis, while other patients may progress all the way to tertiary syphilis.
There are four stages of syphilis: primary, secondary, latent, and tertiary syphilis. At the end of the primary stage, or during the latent stage, the patient may cease to progress through the later stages of the disease for reasons that are still largely unknown. During latent syphilis, the progression of the disease may also stop due to antimicrobial drug use in developed countries. Additionally, if the disease is detected during the primary stage and treated, then no further progression will occur. However, many people do not know they are infected with Treponema pallidum because they do not notice the chancre that is the major sign of the primary stage; therefore, progression of the disease is usually assured in these cases.
Which of the following is a defining characteristic of coliforms?
They are strictly anaerobic.
The major symptoms of cholera are attributable to which of the following?
activation of adenylate cyclase
Which of the following is associated with some cases of streptococcal pharyngitis?
acute glomerulonephritis, scarlet fever and rheumatic fever
Which of the following agents involved in food-borne illness is a eukaryote?
Toxoplasma gondii
Compare the use of biosensors with traditional methods of determining microbial contamination.
Traditional methods of detecting microbial contaminants rely on collecting samples containing living microbes and being able to culture them in the laboratory. The need to provide the right growth conditions reduces the sensitivity of such tests. Waiting for the organisms to grow makes traditional methods time consuming. Biosensors use bacteria or bacterial enzymes to detect small amounts of contaminants in samples. The results are available in minutes rather than hours or days. Detection does not rely on properly anticipating an organism's growth requirements. Biosensors can also be designed to distinguish between closely related organisms, for example, by detecting whether a toxin is present in the sample. Biosensors are faster and more sensitive than traditional methods, and they are potentially more effective in distinguishing truly harmful microbes from their harmless close relatives.
Trypanosoma cruzi is transmitted by which of the following?
Triatoma bugs
Which of the following is the cause of the most common curable STD in women?
Trichomonas vaginalis
List and describe the three stages of malaria, paying attention to the various forms of the protozoan parasite present in each stage of the disease.
Two of the three stages of malaria occur in a human, and the third stage occurs in mosquitoes. The human stages begin with the exoerythrocytic cycle, when mosquitoes inject sporozoites into the bloodstream. These sporozoites reproduce in the liver to form merozoites, which are released into the blood. Merozoites then penetrate red blood cells and launch the second human stage, which is the erythrocytic cycle. The merozoites become trophozoites inside red blood cells, and these trophozoites can, in turn, reproduce to become more merozoites, which spontaneously lyse the erythrocytes, causing the characteristic cycles of fever and chills associated with malaria. Other merozoites develop into gametocytes, which can be ingested by the female Anopheles mosquito to launch the third cycle, the sporogonic cycle. These gametocytes go through a process of sexual reproduction inside the mosquito, eventually resulting in the formation of sporozoites once again. These sporozoites migrate to the mosquito's salivary glands, and the malaria cycle begins all over again.
The causative agent of bubonic and pneumonic plague is
Yersinia pestis.
The typical sign of primary syphilis is
a chancre at the site of infection
Pneumocystis jiroveci is
a common member of the respiratory microbiota in humans.
chlorinated water contains
a decreased microbial load
A large number of people experience a high fever with a rash during the summer months in a small country. Epidemiologists suspect an emerging disease. Both Aedes and Anopheles mosquitoes are endemic to the country. Researchers are able to detect +ssRNA in the blood of fever victims and in some mosquitoes. What type of pathogen might be responsible for the epidemic?
a flavivirus
Which of the following sets of characteristics describes the highest level of threat potential from biological weapons?
a human pathogen easily produced as an aerosol and transmissible by respiratory aerosols
Dengue hemorrhagic fever is actually
a hyperimmune response to reinfection with dengue virus.
The fermentation product known as silage is
a means of making plant materials more appealing to livestock.
Influenzaviruses are exhibiting increased resistance to which of the following drugs?
amantadine
Rennin is
an enzyme used to make cheese.
A researcher studying the impact of agricultural pesticides on native plants discovers a bacterium capable of degrading small amounts of a specific pesticide. The researcher then modifies the bacterial species in the lab to increase the rate of pesticide degradation. This research represents
applied micro and enviro micro
Where in a tapeworm would you expect to find fertilized eggs?
at the end of the strobila
The normal hosts for Ebola viruses are probably
bats
Pathogenic streptococci of the upper respiratory tract (such as Streptococcus pyogenes) are distinguished from non-pathogenic streptococci by
beta hemolytic activity.
Which of the following serotypes of Salmonella enterica causes most cases of human salmonellosis in the United States?
both Enteritidis and Typhimurium
syphillis can be trasmitted
both by sexual contact and from mother to fetus
Which of the following is transmitted by Aedes mosquitoes?
both dengue fever and yellow fever
A vaccine is available against which of the following?
both hepatitis A and hepatitis B
Coronaviruses cause
both the common cold and SARS.
Unprotected contact with the bodily fluids of an infected animal may result in
brucellosis.
Which of the following is characteristic of Yersinia pestis infections?
buboes
Trichomonas vaginalis is usually transmitted via sexual intercourse because it
cannot live long outside the body
Pap smears are used in the diagnosis of
cervical cancer
Which of the following results when ethanol is allowed to oxidize to acetic acid following the fermentation of fruit, grain, or vegetables?
champagne
rennin is used in the production of
cheese
Which of the following can mimic gonorrhea infections?
chlamydia
A young adult shows up at a free clinic complaining of painful swellings in the groin. The young woman has a history of occasional casual sex, but denies noticing any genital sores or experiencing painful urination. The young woman is most likely infected with
chlamydia trachomatis
the most common sexually transmitted bacterium is
chlamydia trachomatis
Blastomycosis results from
contact with fomites.
Even though mycoplasmas pass through filters that normally trap bacteria, they are known to be bacteria, not viruses, because they
contain both DNA and RNA and divide by binary fission
Potable water is water that
contains low amounts of microorganisms and is considered safe to drink
Tapeworms are usually transmitted to humans through ingestion of
cysticerci.
microbial infection of the bladder is called
cystitis
The typical signs and symptoms of flu are a result of
cytokines released as part of the immune response.
Which of the following is known to be teratogenic?
cytomegalovirus
A young woman develops a fever after a recent trip to a Caribbean island. She also experiences severe headache and pain "in the bones." After a few days, she also develops a rash. Which of the following did she most likely contract?
dengue virus
Streptococcus mutans is associated with
dental caries.
Bordetella pertussis produces
dermonecrotic, adenylate cyclase and pyrogenic toxins.
A diagnosis of genital herpes is confirmed by the
detection of herpesvirus DNA by PCR
Francisella can be transmitted by all of the following EXCEPT
direct contact with an infected person.
Streptokinase is involved in which of the following?
dissolving blood clots
salt and sugar act as preservatives by
drawing water out of food
Vegetations are associated with which of the following disease processes?
endocarditis
Which of the following types of bacterial toxins is associated exclusively with Gram-negative bacteria?
endotoxin
mature sperm cells are stored in a male's
epididymis
Which of these microbial products is needed to produce "gasohol"?
ethanol
The chief diagnostic sign of brucellosis is
fever which recurs at 24 hour intervals.
Ebola hemorrhagic fever is caused by which of the following virus types?
filoviruses
A large number of people in a community experience diarrhea with fever. Public health authorities investigate and find that the people are passing dark urine, and some have yellowish skin. Furthermore, all of the affected individuals recently ate at a new restaurant in town known for its wide variety of fresh imported vegetables. Which of the following is the most likely causative agent?
hepatitis A virus
A man reports to his doctor that he is tired all the time and his urine has become darker in color. He has not experienced fever or vomiting recently. The physician notes that his eyes are yellowish and his abdomen is swollen. The man has a history of kidney transplant and recently returned from an overseas trip. The man may be infected with
hepatitis E virus.
An indication of infection with Human herpesvirus 4 is
high fever and sore throat.
Which of the following is the most common fungal systemic disease in humans?
histoplasmosis
Which of the following contributes to the invasiveness of Treponema pallidum?
hyaluronidase
During treatment of water to make it potable, about 90% of the microbes are removed
in the filtration step
Pickling is an effective means of food preservation involving
increasing salt concentration or reducing pH or both
which of the following transmits leptospirosis
infected animal urine
A woman who breeds parrots develops a fever and cough, and begins to have difficulty breathing. Small Gram-negative bacteria are detected inside cells of a sputum sample. Which of the following diseases is she likely to have contracted?
inhalation anthrax
Bordetella pertussis causes whooping cough by
interfering with the activity of ciliated epithelial cells in the trachea.
The most important virulence factor of Vibrio cholerae is
its ability to produce a potent exotoxin.
Which of the following common food products is prepared by the fermentation of cabbage?
kimchi
Which of the following is an opportunistic infection?
legionellosis
During the spring calving season a ranch hand begins to run a fever and feel nauseous and achy. After he develops a headache and vomiting, he goes to a clinic. A microscopic exam of a urine sample reveals long thin microbes which move very rapidly in a corkscrewing pattern. The man may have contracted
leptospirosis
In addition to the genital tract, various strains of Chlamydia trachomatis can infect which of the following?
lymph nodes, lungs, and conjunctiva
Infection of the lymphatic vessels is known as
lymphangitis.
Shigellosis can be differentiated from salmonellosis by the fact that Shigella
multiplies in the host cell's cytosol.
Accessory organ infections are caused by
mumps virus.
A new industrial park in your community dumps its wastewater into a large aerated pond, to which nutrients are added. The water from this pond makes its way into a nearby marsh, which eventually drains into a slow-moving stream. This is an example of
natural bioremediation
The presence of Gram-negative diplococci in pus from an inflamed penis is diagnostic for infection by
neisseria gonorrhoeae
Of the following, who is most likely to develop a chronic infection with hepatitis B virus?
newborns
Which of the following diseases associated with Epstein-Barr virus is commonly seen in AIDS patients?
oral hairy leukoplakia
Ophthalmia neonatorum is an infection caused by
staphylococcus aureus
"Swimmer's itch" is an initial symptom of which of the following?
schistosomiasis
Differentiation between Taenia saginata and Taenia solium is carried out via examination of the
scolex.
A person is brought to the emergency room with constant high fever, extensive edema, low blood pressure, and petechiae. Which of the following may the person be suffering from?
septicemia
Disseminated intravascular coagulation is a complication of which of the following?
septicemia
Whole blood with the formed elements and clotting proteins removed is called
serum.
Which of the following infectious diseases currently tops the list of bioterrorist threats?
smallpox
The fungus Aspergillus oryzae is used in the production of
soy sauce
Coccidioides germinates in the alveoli into a form called a(n)
spherule.
Which of the following diseases is a major problem for AIDS patients?
toxoplasmosis
The major sign of Haemophilus ducreyi infection is similar to the major sign of infection by
treponema pallidum
A woman goes to her gynecologist and reports that she is experiencing pain during intercourse and frequently has an unusual vaginal discharge that is increased in quantity and sort of foamy. A vaginal smear shows normal appearing epithelial cells along with small leaf-shaped cells with prominent oval nuclei. What disease is the woman experiencing?
trichomoniasis
Which of the following is the infective form of Trypanosoma cruzi?
trypomastigotes
Peritonitis may develop in severe cases of
typhoid.
Another name for brucellosis is
undulant fever.
Industrial fermentation and fermentation in food production
use entirely different starting material.
Which of the following pairs is mismatched?
white wine — must
Sulfur dioxide is added to "must" in the production of
wine
what type of infection is candidiasis
yeast
"Black vomit" is associated with which of the following diseases?
yellow fever
Which of the following diseases is currently vaccine-preventable in humans?
yellow fever
Epstein-Barr virus infections are typically asymptomatic in which of the following groups? A) the elderly
young children
