Microbiology Final Exam Chapter 20

MacConkey agar is selective for Haemophilus influenzae.

False

Moraxella is a common cause of bacteremia

False

Some scientists believe that Shigella may actually be a strain of Escherichia coli that has become oxidase positive.

False

Which of the following statements regarding Neisseria meningitidis is FALSE? A) There are vaccines available to prevent infection with all strains. B) Up to 40% of the population are carriers. C) Humans are the only natural carriers. D) Transmission is via respiratory droplets. E) It often causes meningitis.

A

Which of the following are characteristics of pathogenic strains of Neisseria that are useful for identifying them in the laboratory? A) oxidase enzyme activity B) fastidious growth requirements C) diplococcus D) oxidase enzyme activity and fastidious growth requirements E) diplococcus with oxidase enzyme activity and fastidious growth requirements

E

Legionnaires' disease is diagnosed by A) the microbe's characteristic growth on common laboratory media. B) the microbe's staining properties under the microscope. C) fluorescent antibody or other serological diagnostic procedures. D) the clinical symptoms in infected patients. E) the microbe's sensitivity to all antimicrobial agents.

C

Neisseria is A) easy to grow in the laboratory. B) impossible to grow in the presence of high levels of carbon dioxide. C) the only genus of Gram-negative cocci that regularly causes disease in humans. D) difficult to differentiate from other Gram-negative cocci and bacilli. E) able to withstand unfavorable environmental conditions such as drying and extreme heat.

C

What is the antimicrobial agent of choice for treating Bacteroides infections? A) erythromycin B) tetracycline C) metronidazole D) cephalosporin E) bacitracin

C

What is the causative pathogen of Q fever? A) Bacteroides fragilis B) Prevotella C) Coxiella burnetii D) Moraxella catarrhalis E) Acinetobacter

C

What virulence factor(s) do all proteobacteria share? A) proteases that destroy IgA antibodies B) fimbriae C) lipid A D) a glycocalyx E) fimbriae and a glycocalyx

C

Which of the following statements regarding Coxiella is FALSE? A) It is an obligate intracellular parasite that grows within phagolysosomes. B) It produces an infective body similar in structure and function to endospores produced by some Gram-positive species. C) It must use its host's ribosomes. D) It prefers an acid environment. E) It was once thought to be a virus.

C

Members of the Enterobacteriaceae can be distinguished from each other by A) the presence or absence of the enzyme oxidase. B) the ability to ferment lactose. C) motility. D) motility and the presence or absence of the enzyme oxidase. E) motility and the ability to ferment lactose.

E

Several cases of severe, nonbloody diarrhea with fever and abdominal pain have occurred among a number of people who ate at the same restaurant. Public health officers find a food sample containing noncoliform, nonmotile Gram-negative bacteria capable of metabolizing urea. The "food poisoning" resulted from contamination with A) Citrobacter. B) Escherichia coli. C) Salmonella. D) Shigella. E)Yersinia.

E

Untreated gonorrhea in women can lead to a condition known as ________.

pelvic inflammatory disease

The zoonosis ________ can be acquired by humans in a variety of ways, including insect bites and ingestion of infected animals.

tularemia

The ________ in enteric bacteria allows them to form channels through which bacterial proteins are introduced into the host cell, helping them evade immune surveillance.

type III secretion system

A young woman has a pelvic infection. A specimen contains bacilli that are bile salt tolerant, as shown by growth on a bile-esculin agar plate. Her infection is likely caused by A) Bacteroides fragilis. B) Bartonella henselae. C) Haemophilus ducreyi. D) Neisseria gonorrhoeae. E) Pseudomonas aeruginosa.

A

Among the areas of the female genital tract, which of the following is NEVER infected with Neisseria gonorrhoeae? A) the vagina B) the cervix C) the uterus D) the Fallopian tubes E) the pelvic organs

A

Hemolytic uremic syndrome is caused by A) Escherichia coli O157:H7. B) Serratia marcescens. C) Proteus mirabilis. D) Bacteroides fragilis. E) Enterobacter.

A

How do Prevotella differ from Bacteroides? A) They are sensitive to bile. B) They are anaerobic. C) They are pleomorphic bacilli. D) They are found in the intestinal, respiratory, and urinary tracts. E) They possess antiphagocytic capsules.

A

What is the causative pathogen for bubonic and pneumonic plague? A) Yersinia pestis B)Yersinia enterocolitica C)Yersinia pseudotuberculosis D) Salmonella enterica E) Salmonella flexneri

A

What is the characteristic lesion of Yersinia pestis? A) a bubo B) a chancroid C) a soft chancre D) petechiae E) oozing abscesses in the intestinal wall

A

Which of the following coliforms is the most common cause of non-nosocomial urinary tract infections? A) Escherichia coli B) Serratia marcescens C) Proteus mirabilis D) Klebsiella pneumoniae E) Enterobacter

A

Which of the following diseases can be prevented by vaccination? A) typhoid fever B) salmonellosis C) cat scratch disease D) gonorrhea E) chancroid

A

Which of the following is diagnostic for Neisseria meningitidis? A) the presence of Gram-negative diplococci in phagocytes of the central nervous system B) its inability to ferment maltose C) the presence of lipid A D) the lack of lipooligosaccharide E) the lack of fimbriae

A

Neisseria meningitidis is able to survive inside macrophages and be transported throughout the body in them.

True

Why is treatment with antimicrobial drugs NOT encouraged in patients with diarrhea caused by enteric bacteria?

Antimicrobial treatment of enteric diarrhea can worsen the prognosis by killing many bacteria at once, releasing large amounts of lipid A. The release of lipid A from these bacteria causes fever, vasodilation, inflammation, shock, and DIC, potentially leading to death. In addition, the diarrhea is normally self-limiting, and the expulsion of the organisms from the body is often more effective than antimicrobial treatment.

Bordetella pertussis, the pathogen responsible for whooping cough, causes disease by A) the development of pneumonia. B) interfering with the action of the ciliated epithelial cells of the trachea. C) suppressing the production of mucus by the respiratory lining. D) forming a pseudomembrane that obstructs the larynx. E) irritating the diaphragm, which leads to severe coughing attacks.

B

Cat scratch disease is caused by A) Bartonella bacilliformis. B) Bartonella henselae. C) Bartonella quintana. D) Bartonella peliosis. E) Bartonella angiomatosis.

B

Serratia is a coliform that A) is nonmotile. B) produces red pigment when grown at room temperature. C) is totally benign in humans. D) is easy to treat because it is sensitive to most antibiotics. E) may grow on catheters but not in other hospital supplies such as saline and other salt solutions.

B

Which of the following bacteria were formerly classified in the same family as Neisseria? A) Francisella B) Moraxella C) Bordetella D) Coxiella E) Pasteurellaceae

B

Which of the following organisms produces concentric wavelike patterns due to swarming cells when it is cultured on agar? A) Klebsiella B) Proteus C) Pseudomonas D) Salmonella E) Shigella

B

Dermonecrotic toxin is produced by ________ and causes localized constriction and hemorrhage of blood vessels, resulting in cell death and tissue destruction.

Bordetella pertussis

Compare and contrast acute bacterial meningitis and meningococcal meningitis, including etiologic agents, pathology, and epidemiology.

Both diseases are transmitted in aerosols or droplets of upper respiratory secretions and are potentially fatal. Both diseases are preventable by vaccination. Both pathogens are fastidious, growing primarily on chocolate agar plates, and are oxidase positive. Acute bacterial meningitis is caused by Haemophilus influenzae b, a facultatively anaerobic pleomorphic bacterium in the family Enterobacteriaceae. H. influenzae most commonly causes disease in children under two years of age. H. influenzae has a capsule that makes it resistant to phagocytosis. Meningococcal meningitis is caused by Neisseria meningitidis, a Gram-negative aerobic diplococcus. N. meningitidis often causes meningitis in young adults, although young children are also susceptible. N. meningitidis has a polysaccharide capsule that does not prevent phagocytosis but resists digestion once inside phagocytes. As a consequence, N. meningitidis becomes an intracellular parasite of phagocytes.

Compare and contrast Yersinia pestis and Francisella tularensis with respect to clinical manifestations, mechanisms of transmission, reservoirs, and pathogenesis.

Both organisms can result in a pulmonary form of the disease if the bacterium travels via the blood or aerosol to the respiratory tract. Yersinia can also be transmitted to the respiratory tract person to person if it is pneumonic; Francisella cannot. Both organisms can infect and cause a skin ulcer to form at the site of the site of infection. Both organisms can be transmitted by an arthropod vector. For Y. pestis the vector is usually a flea, whereas for F. tularensis vectors can be flies, mosquitoes, mites, or ticks. Francisella can also be transmitted by contact with contaminated animals, by ingesting contaminated animals or water, or by inhaling aerosols. Yersinia can be transmitted from a scratch from an infected animal or contact with the animal. Francisella has many hosts; rabbits, ticks, and muskrats are the most common reservoirs. Rodents are the most common reservoirs for Yersinia. Yersinia is pathogenic by injecting deadly proteins into macrophages and neutrophils, whereas Francisella is an intracellular parasite that inhibits phagocytosis by an unknown mechanism.

________, caused by Yersinia pestis, is not spread from person to person.

Bubonic plague

A cystic fibrosis patient develops a severe respiratory infection that resists treatment with standard antibiotics. A specimen from the lungs is greenish in color and contains aerobic motile Gram-negative bacilli. The patient is probably infected with A) Bordetella pertussis. B) Burkholderia cepacia. C) Klebsiella pneumoniae. D) Pseudomonas aeruginosa. E) Serratia marcescens.

D

A lung specimen from a pneumonia patient contains Gram-negative bacilli. Laboratory test results on the bacteria show they are nonmotile coliforms with a capsule. Which pathogen is the likely cause of the pneumonia? A) Escherichia coli B) Enterobacter C) Hafnia D) Klebsiella E) Serratia

D

Lipid A causes which of the following symptoms? A) hemorrhaging B) fever C) disseminated intravascular coagulation (DIC) D) fever and disseminated intravascular coagulation (DIC) E) fever and hemorrhaging

D

Resistance of Pseudomonas to a wide range of antibacterial agents is partly due to its A) production of exoenzyme S. B) use of the Entner-Doudoroff pathway as its major means of catabolizing glucose. C) ability to utilize a wide range of organic and nitrogen sources. D) ability to form biofilms. E) lack of special requirements for growth.

D

Shigellosis can be differentiated from salmonellosis by A) the lack of fever. B) the presence of bloody diarrhea. C) the presence of nonmotile noncoliforms. D) the presence of nonmotile noncoliforms in bloody diarrhea. E) abdominal cramps and fever.

D

The major damage caused by Neisseria meningitidis is a result of A) its invasion into the central nervous system. B) its presence in the respiratory tract of 40% of healthy individuals. C) its ability to be transmitted by droplets among people who live in close contact. D) the release of the lipid A component of lipooligosaccharide (LOS) into the tissues, triggering serious symptoms. E) the fact that it can survive in cells after phagocytosis

D

Which of the following bacteria requires heme for its growth? A) Salmonella B) Shigella C)Yersinia D) Haemophilus E) Bordetella

D

Which of the following pairs is MISMATCHED? A) coliform Enterobacteriaceae - rapid lactose fermenters B) noncoliform opportunistic Enterobacteriaceae - Proteus, Morganella C) coliform Enterobacteriaceae - opportunistic pathogens D) nonpathogenic Enterobacteriaceae - Salmonella, Shigella E) noncoliform Enterobacteriaceae - non-lactose-fermenters

D

Which of the following statements about Neisseria gonorrhoeae is FALSE? A) It causes disease in humans only. B) The gonococci stick to epithelial cells via fimbriae and capsules. C) The gonococci secrete a protease that destroys secretory IgA. D) The gonococci can multiply inside macrophages. E) Infected women are often asymptomatic.

D

Which of the following statements concerning Pasteurella is FALSE? A) It is oxidase positive. B) It is nonmotile. C) Humans are typically infected via animal bites. D) It is fastidious in its growth and must be cultivated on blood or chocolate agar. E) It is very resistant to a wide variety of antibacterial drugs such as penicillins, sulfonamides, trimethoprim, and fluoroquinolones.

E

Which of the following toxins produced by Bordetella pertussis result(s) in the accumulation of excess mucus in the trachea? A) pertussis toxin B) adenylate cyclase toxin C) tracheal cytotoxin D) adenylate cyclase toxin and tracheal cytotoxin E) pertussis toxin and adenylate cyclase toxin

E

Coxiella burnetii is transmitted to humans mainly via the bite of infected tick vectors.

False

Enterobacteriaceae are rarely pathogenic

False

Gonococcal infections result in lifelong immunity against Neisseria gonorrhoeae.

False

Pneumonia caused by ________ often involves the destruction of alveoli and the production of bloody sputum.

Klebsiella pneumoniae

The pleomorphic bacterium ________ is an intracellular parasite that can lead to respiratory disease when inhaled in aerosols from moist environments.

Legionella

Among the variety of virulence factors possessed by pathogenic enteric bacteria, which one allows them to evade the immune surveillance of its host?

Most pathogenic enteric bacteria possess a type III secretion system, which is a complex structure composed of 20 different polypeptides. Once assembled, the system spans the two membranes and peptidoglycan of the bacterial cell and inserts into the host's cytoplasmic membrane. This forms a channel through which bacterial proteins are introduced into the host cell. Because the bacteria synthesize type III systems only after they have contact with a host cell, the type III proteins are never exposed to leukocytes. This helps these bacteria evade immune surveillance.

Of all the types of Proteus, ________ is the most common species associated with disease in humans.

P. mirabilis

________ are gammaproteobacteria that are oxidase positive and require cytochromes or heme as part of their growth requirements.

Pasteurellaceae

Infection with ________ can frequently be diagnosed by the presence of blue-green discoloration of tissue.

Pseudomonas aeruginosa

________ is a medical puzzle because even though it expresses a wide range of virulence factors, it rarely causes disease.

Pseudomonas aeruginosa

Scientists have identified over 2000 unique serotypes of Salmonella, but DNA analysis indicates that they belong to a single species: ________.

S. enterica

How does Salmonella grow in host cells? How does it differ from Shigella?

Salmonella is usually ingested by way of contaminated food and drink. After the microbes pass through the stomach, they attach to the cells lining the small intestine. There the bacteria insert proteins into the host cells, inducing normally nonphagocytic cells to phagocytize the bacteria. The bacteria reproduce within the phagocytic vessels and end up killing the host cells. Shigella uses a similar path, but it reproduces within the cell's cytosol.

By controlling the genetic expression of Vi and H antigens, Salmonella evades the host's immune system and manages to survive.

True

Haemophilus ducreyi is transmitted sexually.

True

Humans are the sole hosts of Salmonella typhi

True

Intravenous ceftriaxone is the drug of choice for treating meningococcal meningitis.

True

Lipid A causes disseminated intravenous coagulation (DIC).

True

Because of the existence of ________ carriers, the eradication of meningococcal disease is unlikely.

healthy asymptomatic

Antimicrobial therapy in individuals infected with Enterobacteriaceae may worsen the prognosis because of the release of large amounts of ________.

lipid A

Neisseria is distinguished from many other Gram-negative pathogens by being ________ positive.

oxidase