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129 Cards in this Set
- Front
- Back
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1) A commensal bacterium
A) Does not receive any benefit from its host. B) Is beneficial to its host. C) May be an opportunistic pathogen. D) Does not infect its host. E) B and D only |
Answer: C
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2) Which of the following statements is true?
A) Symbiosis refers to different organisms living together. B) Members of a symbiotic relationship cannot live without each other. C) A parasite is not in symbiosis with its host. D) Symbiosis refers to different organisms living together and benefiting from each other. E) At least one member must benefit in a symbiotic relationship. |
Answer: A
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3) A nosocomial infection is
A) Always present but is inapparent at the time of hospitalization. B) Acquired during the course of hospitalization. C) Always caused by medical personnel. D) Only a result of surgery. E) Always caused by pathogenic bacteria. |
Answer: B
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4) The major significance of Koch's work was that
A) Microorganisms are present in a diseased animal. B) Diseases can be transmitted from one animal to another. C) Microorganisms can be cultured. D) Microorganisms cause disease. E) Microorganisms are the result of disease. |
Answer: D
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5) Koch's postulates don't apply to all diseases because
A) Some microorganisms can't be cultured in laboratory media. B) Some microorganisms don't cause the same disease in laboratory animals. C) Some microorganisms cause different symptoms under different conditions. D) Some microorganisms can't be observed. E) Not all diseases are caused by microorganisms. |
Answer: E
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6) Which of the following diseases is NOT spread by droplet infection?
A) Botulism B) Tuberculosis C) Measles D) Common cold E) Diphtheria |
Answer: A
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7) Mechanical transmission differs from biological transmission in that mechanical transmission
A) Doesn't require an arthropod. B) Involves fomites. C) Doesn't involve specific diseases. D) Requires direct contact. E) Doesn't work with noncommunicable diseases. |
Answer: C
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8) Which of the following definitions is incorrect?
A) Endemic – a disease that is constantly present in a population B) Epidemic – fraction of the population having a disease at a specified time C) Pandemic – a disease that affects a large number of people in the world in a short time D) Sporadic – a disease that affects a population occasionally E) Incidence – number of new cases of a disease |
Answer: B
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9) Which of these infections can cause septicemia?
A) Bacteremia B) Focal infection C) Local infection D) Septicemia E) Systemic infection |
Answer: B
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10) Which type of infection can be caused by septicemia?
A) Bacteremia B) Focal infection C) Local infection D) Viremia E) Systemic infection |
Answer: E
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11) Koch observed Bacillus anthracis multiplying in the blood of cattle. What is this condition called?
A) Bacteremia B) Focal infection C) Local infection D) Septicemia E) Systemic infection |
Answer: D
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12) Which one of the following does NOT contribute to the incidence of nosocomial infections?
A) Formation of biofilms B) Lapse in aseptic techniques C) Gram-negative cell walls D) Lack of handwashing E) Lack of insect control |
Answer: C
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13) Transient microbiota differ from normal microbiota because transient microbiota
A) Cause diseases. B) Are found in a certain location on the host. C) Are acquired by direct contact. D) Are present for a relatively short time. E) Never cause disease. |
Answer: D
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14) Which of the following statements about nosocomial infections is false?
A) They occur in compromised patients. B) They are caused by opportunists. C) They are caused by drug-resistant bacteria. D) They are caused by normal microbiota. E) The patient was infected before hospitalization. |
Answer: E
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15) One effect of washing regularly with antibacterial agents is the removal of normal microbiota. This can result in
A) Body odor. B) Fewer diseases. C) Increased susceptibility to disease. D) Normal microbiota returning immediately. E) No bacterial growth because washing removes their food source. |
Answer: C
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16) Which of the following is NOT a reservoir of infection?
A) A sick person B) A healthy person C) A sick animal D) A hospital E) All of the above can be reservoirs of infection. |
Answer: E
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17) Which of the following is NOT a communicable diseases?
A) Malaria B) AIDS C) Tuberculosis D) Tetanus E) Typhoid fever |
Answer: D
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18) Which of the following is a fomite?
A) Water B) Droplets from a sneeze C) Pus D) Insects E) A hypodermic needle |
Answer: E
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19) Which of the following statements about biological transmission is false?
A) The pathogen reproduces in the vector. B) The pathogen may enter the host in the vector's feces. C) Houseflies are an important vector. D) The pathogen may be injected by the bite of the vector. E) The pathogen may require the vector as a host. |
Answer: C
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20) Which of the following definitions is incorrect?
A) Acute – a short-lasting primary infection B) Inapparent – infection characteristic of a carrier state C) Chronic – a disease that develops slowly and lasts for months D) Primary infection – an initial illness E) Secondary infection – a long-lasting illness |
Answer: E
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21) Symptoms of disease differ from signs of disease in that symptoms
A) Are changes felt by the patient. B) Are changes observed by the physician. C) Are specific for a particular disease. D) Always occur as part of a syndrome. E) None of the above. |
Answer: A
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22) The science that deals with when diseases occur and how they are transmitted is called
A) Ecology. B) Epidemiology. C) Communicable disease. D) Morbidity and mortality. E) Public health. |
Answer: B
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24) Emergence of infectious diseases can be due to all of the following EXCEPT
A) Antibiotic resistance. B) Climatic changes. C) Digging up soil. D) Microbes trying to cause disease. E) Travel. |
Answer: D
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25) Which of the following pairs is mismatched?
A) Malaria – vector B) Salmonellosis – vehicle transmission C) Syphilis – direct contact D) Influenza – droplet infection E) All of the above are correctly matched. |
Answer: E
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26) Which of the following can contribute to postoperative infections?
A) Using syringes more than once B) Normal microbiota on the operating room staff C) Errors in aseptic technique D) Antibiotic resistance E) All of the above |
Answer: E
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28) A cold transmitted by a facial tissue is an example of
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: E
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29) Influenza transmitted by an unprotected sneeze is an example of
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: B
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30) A sexually transmitted disease is an example of
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: A
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31) Gastroenteritis acquired from roast beef is an example of
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: E
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32) A needlestick is an example of
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: C
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33) Legionellosis transmitted by a grocery store mist machine is an example of
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: E
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34) Plague transmitted by a flea is an example of
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: D
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35) The most likely mode of transmission of pneumonic plague between humans is
A) Direct contact. B) Droplet transmission. C) Fomite. D) Vector. E) Vehicle transmission. |
Answer: B
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Situation 14.1
During a 6-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 3 years. 36) Situation 14.1 is an example of A) Human reservoirs. B) A zoonosis. C) A nonliving reservoir. D) A vector. E) A focal infection. |
Answer: B
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Situation 14.1
During a 6-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 3 years. 37) In Situation 14.1, the etiologic agent of the disease is A) Sheep. B) Soil. C) Coxiella burnetii. D) Pneumonia. E) Wind. |
Answer: C
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Situation 14.1
During a 6-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 3 years. 38) In Situation 14.1, the method of transmission of this disease was A) Direct contact. B) Droplet. C) Indirect contact. D) Vector-borne. E) Vehicle. |
Answer: E
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39) Which one of the following is NOT an example of microbial antagonism?
A) Acid production by bacteria B) Bacteriocin production C) Bacteria occupying host receptors D) Bacteria causing disease E) Bacteria producing vitamin K |
Answer: D
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40) The yeast Candida albicans does not normally cause disease because of
A) Symbiotic bacteria. B) Antagonistic bacteria. C) Parasitic bacteria. D) Commensal bacteria. E) Other fungi. |
Answer: B
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41) Haemophilus bacteria require heme protein produced by Staphylococcus bacteria. This is an example of
A) Antagonism. B) Commensalism. C) Parasitism. D) Synergism. E) Competitive exclusion. |
Answer: D
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42) Which one of the following is NOT a zoonosis?
A) Cat-scratch disease B) Hantavirus pulmonary syndrome C) Rabies D) Tapeworm E) All of the above are zoonoses. |
Answer: E
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43) Pseudomonas bacteria colonized the bile duct of a patient following his liver transplant surgery. This is an example of a
A) Communicable disease. B) Latent infection. C) Nosocomial infection. D) Sporadic disease. E) None of the above. |
Answer: C
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45) Which one of the following statements is false?
A) Antimicrobial therapy for hemodialysis-associated infections increases antibiotic resistance. B) S. aureus is differentiated from other mannitol+ cocci by the coagulase test. C) The M in MRSA stands for mannitol. D) USA100 accounts for most hospital-acquired MRSA. E) USA300 accounts for most community-acquired MRSA. |
Answer: C
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1. Which species of Staphylococcus is one of the most important human pathogens?
a. Staphylococcus aureus b. Staphylococcus epidermidis c. Staphylococcus lugdunensis d. Staphylococcus saprophyticus |
A
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2. Which group of bacteria is described as catalase-positive, gram-positive cocci that grow facultatively anaerobic and form grapelike clusters?
a. Neisseria b. Stomatococcus c. Staphylococcus d. Micrococcus |
C
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3. The first identification test performed on clinical isolates of gram-positive, catalase-positive cocci would be which of the following?
a. Penicillin test b. Bile solubility test c. Oxidase test d. Coagulase test |
D
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4. In clinical isolates, the most likely identification of coagulase-positive, catalase-positive, gram-positive cocci that are penicillin resistant would be which of the following?
a. Staphylococcus aureus b. Staphylococcus intermedius c. Stomatococcus luteus d. Micrococcus aureus |
A
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Which resident human flora staphylococcus is more likely to cause infections in compromised hosts such as cancer patients?
a. Staphylococcus saprophyticus b. Staphylococcus aureus c. Staphylococcus epidermidis d. Staphylococcus lugdunensis |
C
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6. Which type of staphylococcus is more likely to cause uncomplicated urinary tract infections in nonhospitalized hosts, especially sexually active young women?
a. Staphylococcus saprophyticus b. Staphylococcus aureus c. Staphylococcus epidermidis d. Staphylococcus lugdunensis |
A
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7. A baby has blister-like lesions over most of her body, and the skin is readily removed with no scarring. After making the diagnosis, which of the following is true of the infection?
a. Latent infection established in the trigeminal ganglia b. Preventable by maternally acquired antibody c. Requires cell-mediated immune response to limit progression of disease d. Sequelae of sore throat e. Transmitted from the desquamated skin |
B
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A 63-year-old man develops fever within 2 days of surgery for a hip replacement. Treatment with ampicillin does not eliminate the infection. Gram-positive, coagulase-positive cocci were isolated from the blood. Which of the following is the most probable reason for antibiotic failure?
a. Antibiotic-resistant target enzyme b. Chromosomal mutation in ribosome prevents drug action c. Inactivation by coagulase d. Insufficient dosing schedule e. Mutation in porins prevents drug entry |
A
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A 25-year-old woman is seen on an emergency basis while in shock, with generalized flushing of the skin and mucous membranes. A tampon is present in her vagina. Toxic shock syndrome is suspected. Which of the following mechanisms is responsible for toxic shock syndrome?
a. Activation of adenylate cyclase b. ADP ribosylation of ribosomal protein c. Cross-linking of MHC II and TCR proteins d. Inhibition of acetylcholine release e. Stimulation of G protein |
C
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A 35-year-old man complains of rhinitis. A nasal swab of his nares yields Staphylococcus epidermidis. Which of the following actions should be taken?
a. Perform nasal wash with saline. b. No treatment is necessary. c. Test for methicillin resistance. d. Treat contacts with rifampin. e. Treat patient with vancomycin. |
B
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A group of patients was seen on an emergency basis complaining of abdominal cramps and watery diarrhea within 5 hours of attending a picnic in which ham, potato salad, and custard-filled pastries were on the menu. Which of the following is the likely cause of this disease?
a. Attachment and disruption of intestinal lining due to parasitic infection b. Bacterial colonization and toxin production c. Bacterial adherence and invasion d. Preformed bacterial toxin e. Replication of virus that prevents reabsorption of water |
D
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A 65-year-old man develops fever 4 days after a hip replacement. Fever does not dissipate with β-lactam antibiotic treatment. A gram-positive coccus is isolated from the blood. Which of the following antibacterial agents would be the drug of choice in this situation?
a. Ampicillin b. Ciprofloxacin c. Erythromycin d. Rifampin e. Vancomycin |
E
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A 23-year-old woman had sudden onset of fever, dizziness, and a rash. Within 2 days, she had kidney failure, and the skin on her palms and soles sloughed off. Gram-positive, coagulase-positive cocci were cultured from a tampon. Binding of a toxin and activation of which of the following receptors explains the cause or mechanism for the multitude of symptoms?
a. B-cell receptors b. Interleukin-6 receptors c. T-cell receptors d. TGF-β receptors e. Toll-like receptors |
C
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Most of the members of a youth group visited the emergency room with complaints of abdominal cramps and watery diarrhea 4 hours after a picnic. Which of the following bacterial traits facilitate the occurrence of this outbreak?
a. Ability to ferment lactose b. Ability to grow in high salt c. Anaerobic growth d. Lysis of red blood cells in agar e. Production of a double zone on egg yolk agar |
B
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A 67-year-old patient with an indwelling catheter develops fever, and gram-positive cocci are isolated from his blood and from a biofilm on the catheter. Which of the following traits identify these bacteria?
a. β-Hemolysis b. Catalase c. Spore formation d. Growth in bile e. Resistance to methicillin |
B
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A 1-month-old boy developed erythema around his mouth, which then covered his body within 2 days. The skin became covered with blisters, and the top layer of epidermis was sloughed off. Which of the following is consistent with the mechanism of this disease?
a. Coagulase b. Lecithinase c. Lipase d. Phage e. Toxin |
E
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A group of picnickers develops abdominal cramps and diarrhea within 4 hours of eating. Which of the following foods is most likely the source of the gastroenteritis?
a. Chicken b. Hamburger c. Homemade salami d. Ice cream e. Lettuce |
C
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A 60-year-old man underwent organ transplantation and was placed on immunosuppressive therapy following surgery. What virus is a major threat to this patient, and what is the effective antiviral drug that would be used to treat him?
a. HSV and acyclovir b. CMV and ganciclovir c. Hepatitis C and ribavirin d. HIV and AZT e. VZV and acyclovir |
B
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A 5-year old-boy presents with vesicular lesions around the crimson border of the lips. A Tzanck smear taken from the base of a lesion demonstrates multinucleated giant cells. Which of the following is a correct description of the probable responsible agent?
a. Enveloped virus with –RNA genome b. Enveloped virus with +RNA genome c. Enveloped virus with dsDNA genome d. Naked capsid virus with dsDNA genome e. Naked capsid virus with +RNA genome |
C
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A 5-year-old boy presents with vesicular lesions around the crimson border of the lips. A Tzanck smear taken from the base of a lesion demonstrates multinucleated giant cells. Which of the following is true about the probable agent?
a. Disinfected with soap b. Preventable by an available vaccine c. Lesion leads to permanent scarring d. Transmitted by the fecal-oral route e. Treatable with azidothymidine (AZT) |
A
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A 24-year-old man complains of sore throat and being very tired. He has fever, lymphadenopathy, hepatosplenomegaly, and when treated empirically for the sore throat with ampicillin, he develops a rash on his chest. Which of the following actions should be taken?
a. Determine ASO titer. b. Determine heterophile antibody titer. c. Examine eyes for conjunctivitis. d. Switch to an appropriate antibiotic to prevent pathologic sequelae. e. Treat with an inhibitor of viral neuraminidase. |
B
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A woman has a headache, slight fever, and vesicular lesions on her vagina that look like a dewdrop on a rose petal. Cell culture of vesicular fluid results in cytopathologic effects, including margination of chromatin, Cowdry type A inclusion bodies, and rare syncytia. Which of the following properties promotes the sexual transmission of this agent?
a. Antigenic variation b. Asymptomatic replication c. IgA protease d. Syncytia formation e. Mannose lectin |
B
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Approximately 70 days after a bone marrow transplant, a patient developed fatigue, hepatitis, and leukopenia. Enlarged cells with a large nuclear inclusion body could be found in the urine. Which of the following is most likely to be responsible for the disease signs?
a. Adenovirus b. Cytomegalovirus c. Hepatitis B virus d. Hepatitis C virus e. Mycobacterium tuberculosis |
B
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A 65-year-old man developed a belt of vesicular lesions along his trunk, which were very painful. No lesions were present anywhere else. What mechanism of spread produced this disease presentation?
a. Blood-borne b. Fecal-oral route c. Neuronal d. Respiratory e. Viremia |
C
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A 23-year-old wrestler develops vesicular lesions on his shoulder. The lesions appear as a dewdrop on a rose petal. Which of the following findings would be most useful in confirming the diagnosis?
a. Hemadsorption b. Koilocytosis c. Negri bodies d. Owl’s eye inclusion bodies e. Syncytia |
E
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A 17-year-old girl has a sore throat and lymphadenopathy. She has been very tired for the last week. Empirical treatment of the sore throat with ampicillin produced a rash. Results of a blood test showed atypical lymphocytes and the presence of heterophile antibody. Which of the following is a likely means of acquisition of this infection?
a. Breathing in close quarters b. Mosquito bite c. Poor hand washing d. Shared water bottle e. Unprotected sex |
D
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A 17-year-old girl has a sore throat and lymphadenopathy. She has been very tired for the last week. Empirical treatment of the sore throat with ampicillin produced a rash. Results of a blood test showed atypical lymphocytes and the presence of heterophile antibody. What is the primary target cell for this disease?
a. B cell b. Fibroblast c. Genital epithelial cell d. Respiratory epithelial cell e. T cell |
A
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A 17-year-old girl has a sore throat and lymphadenopathy. She has been very tired for the last week. Empirical treatment of the sore throat with ampicillin produced a rash. Results of a blood test showed atypical lymphocytes and the presence of heterophile antibody. Which of the following profiles indicates serologic confirmation that this infection is in remission?
Heterophile antibodies VCA-IgM VCA-IgG EA EBNA a. + + - - - b - - + + - c. - - + - - d. + - + + + e. - - + + + |
E
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A healthy 24-year-old man is infected with cytomegalovirus. Which of the following is the most likely outcome?
a. Asymptomatic infection b. Chorioretinitis c. Colitis d. Esophagitis e. Pneumonitis |
A
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A neonate was born to a mother who remained promiscuous while pregnant. The baby had a small head, intracerebral calcification, hepatosplenomegaly, and a rash. The baby’s urine contained cells with owl’s eye inclusion bodies. Which of the following viruses is the most likely cause of this infection?
a. B19 b. Cytomegalovirus c. Epstein-Barr virus d. Herpes simplex virus e. Rubella |
B
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An HIV-positive person with CD4 T-cell levels of 50 per mm3 develops pneumonitis and chorioretinitis. Results of a lung biopsy show an epithelial cell with an owl’s eye inclusion body. Which of the following antiviral drugs would be appropriate for treatment of the pneumonitis and chorioretinitis?
a. Acyclovir b. AZT c. Ganciclovir d. Interferon-α e. Ribavirin |
C
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A 3-year-old boy suddenly develops a high fever (40° C). After the fever dissipates, a rash appears. Which of the following is an appropriate description of the rash?
a. B cells are present in the rash. b. Fever will recur during the rash. c. T cells are present in the rash. d. The rash corresponds to a viremia. e. Virus can be isolated from the rash. |
C
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A 5-year-old girl develops erythema infectiosum with fever, chills, myalgia, and then a distinctive rash on her face that appears as if her cheeks had been slapped. Which of the following aspects of this infection correlate with the pathogenesis of the early phase (fever, chills, myalgia) of the disease?
a. Antibody production b. Latency c. Replication in the lungs d. Replication in the skin e. Viremia |
E
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Which of the following is NOT normal microbiota of the skin?
A) Streptococcus B) Pityrosporum C) Staphylococcus D) Propionibacterium E) Corynebacterium |
A
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An 8-year-old girl has scabs and pus-filled vesicles on her face and throat. Three weeks earlier she had visited her grandmother, who had shingles. What infection does the 8-year-old have?
A) Chickenpox B) Measles C) Fever blisters D) Scabies E) Rubella |
A
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Which of the following pairs is mismatched?
A) Staphylococcus aureus – impetigo B) Streptococcus pyogenes – erysipelas C) Propionibacterium acnes – pimples D) Pseudomonas aeruginosa – otitis externa E) Str. pyogenes – toxic shock syndrome |
C
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The etiologic agent of warts is
A) Papovavirus. B) Poxvirus. C) Herpesvirus. D) Parvovirus. E) Staphylococcus aureus . |
A
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Which of the following is NOT a characteristic of Pseudomonas aeruginosa?
A) Gram-positive cell wall B) Oxidative metabolism C) Oxidase-positive D) Produce pyocyanin E) Rod shaped |
A
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Which of the following pairs is mismatched?
A) Pustular rash – smallpox B) Koplik spots – rubella C) Papular rash – measles D) Vesicular rash – chickenpox E) Macular rash – fifth disease |
B
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Which of the following is NOT transmitted by the respiratory route?
A) Smallpox B) Chickenpox C) Rubella D) Trichophyton E) Measles |
D
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Which of these is NOT caused by herpesvirus?
A) Chickenpox B) Shingles C) Keratitis D) Smallpox E) Roseola |
D
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Thrush and vaginitis are caused by
A) Herpesvirus. B) Chlamydia trachomatis. C) Candida albicans. D) Staphylococcus aureus. E) Streptococcus pyogenes. |
C
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The greatest single cause of blindness in the world is
A) Neonatal gonorrheal ophthalmia. B) Keratoconjunctivitis. C) Trachoma. D) Inclusion conjunctivitis. E) Pinkeye. |
C
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Which of the following can be treated with topical chemotherapeutic agents?
A) Herpes gladiatorium B) Sporotrichosis C) Dermatomycosis D) Rubella E) Shingles |
C
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Which of the following is NOT a cause of ringworm?
A) Microsporum B) Trichophyton C) Tinea capitis D) Epidermophyton E) All of the above may cause ringworm. |
C
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Newborns' eyes are treated with an antibiotic
A) When Neisseria gonorrhoeae is isolated from the eyes. B) When the mother is blind. C) When the mother has genital herpes. D) When the mother has gonorrhea. E) Always. |
E
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A possible complication of herpetic keratitis is
A) Encephalitis. B) Fever blisters. C) Subacute sclerosing panencephalitis. D) Congenital rubella syndrome. E) Macular rash. |
A
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Which of the following is sensitive to penicillin?
A) Chlamydia B) Herpesvirus C) Candida D) Streptococcus E) Pseudomonas |
D
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Which region of the skin supports the largest bacterial population?
A) Axilla B) Scalp C) Forearms D) Legs E) All are equal. |
A
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Which infection is NOT caused by Staphylococcus aureus?
A) Pimples B) Sty C) Furuncle D) Carbuncle E) Acne |
E
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Which of the following is NOT a characteristic used to identify Streptococcus pyogenes?
A) Coagulase-positive B) Group A cell wall antigen C) Group M proteins D) Beta-hemolytic E) Cocci |
A
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Which of the following is NOT a causative agent of conjunctivitis?
A) Chlamydia trachomatis B) Herpes simplex C) Adenovirus D) Neisseria gonorrhoeae E) Haemophilus influenzae |
D
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In which of the following respects is measles similar to German measles (rubella)?
A) Rash B) Etiologic agent C) Encephalitis as a complication D) Congenital complications E) In name only |
E
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Vaccination for rubella
A) Is not necessary because the disease is mild. B) Is not necessary if a person has had an infection. C) Is recommended only for pregnant women. D) Is recommended for newborns to prevent congenital disease. E) Has reduced incidence of rubella. |
E
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Which of the following statements about congenital rubella syndrome is false?
A) It is contracted in utero. B) It may be fatal. C) It may result in deafness, blindness, and mental retardation. D) It doesn't occur with subclinical infections. E) All of the above are true. |
D
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The etiologic agent of chickenpox is
A) Herpes simplex. B) Herpes zoster. C) HHV-6. D) Parvovirus. E) Poxvirus. |
B
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The etiologic agent of fifth disease is
A) Herpes simplex. B) Herpes zoster. C) HHV-6. D) Parvovirus. E) Poxvirus. |
D
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The etiologic agent of roseola is
A) Herpes simplex. B) Herpes zoster. C) HHV-6. D) Parvovirus. E) Poxvirus. |
C
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The etiologic agent of fever blisters is
A) Herpes simplex. B) Herpes zoster. C) HHV-6. D) Parvovirus. E) Poxvirus. |
A
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Which of the following is used to treat epidemic herpetic keratitis?
A) Penicillin B) Sulfonamide C) Trifluridine D) Fungicide E) None of the above |
C
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Which of the following is used to treat smallpox?
A) Penicillin B) Sulfonamide C) Trifluridine D) Fungicide E) None of the above |
E
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Which of the following is used to treat sporotrichosis?
A) Penicillin B) Sulfonamide C) Trifluridine D) Fungicide E) None of the above |
D
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Which of the following is used to treat candidiasis?
A) Penicillin B) Sulfonamide C) Trifluridine D) Fungicide E) None of the above |
D
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Scabies is a skin disease caused by
A) A slow virus. B) A protozoan. C) A mite. D) A bacterium. E) A prion. |
C
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Scabies is transmitted by
A) Fomites. B) Food. C) Water. D) Soil. E) B and C. |
A
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A patient has pus-filled vesicles and scabs on her face, throat, and lower back. She most likely has
A) Measles. B) Mumps. C) Chickenpox. D) Rubella. E) Smallpox. |
C
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Which of the following leads to all the others?
A) Toxemia B) Scalded skin syndrome C) Staphylococcal infection D) TSST-1 E) Sudden drop in blood pressure |
C
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Buruli ulcer is caused by
A) Direct contact. B) Acid-fast bacteria. C) A fungus. D) A virus. E) A mite. |
B
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The patient has a papular rash. Microscopic examination of skin scrapings reveals small 8-legged animals. The etiology is
A) Candida B) Microsporum C) Pseudomonas aeruginosa D) Staphylococcus aureus E) Sarcoptes |
E
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The patient has vesicles and scabs over her forehead. Microscopic examination of skin scrapings shows gram-positive cocci in clusters. The etiology is
A) Candida B) Microsporum C) Pseudomonas aeruginosa D) Staphylococcus aureus E) Sarcoptes |
D
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The patient has scaling skin on his fingers. Conidiospores are seen in microscopic examination of skin scrapings. The etiology is
A) Candida B) Microsporum C) Pseudomonas aeruginosa D) Staphylococcus aureus E) Mycobacterium ulcerans |
B
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A 45-year-old man has pus-filled vesicles distributed over his back in the upper right quadrant, over his right shoulder, and upper right quadrant of his chest. His symptoms are most likely due to
A) Candida albicans. B) Herpes simplex virus. C) Staphylococcus aureus. D) Streptococcus pyogenes. E) Varicella-zoster virus. |
E
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A 35-year-old woman has a red, raised rash on the inside of her thighs. Gram-stained skin scrapings show large budding cells with pseudohyphae. The infection is caused by
A) Candida albicans. B) Herpes simplex virus. C) Staphylococcus aureus. D) Streptococcus pyogenes. E) Varicella-zoster virus. |
A
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Cytoplasmic inclusions were observed in a fetus that died in utero after 6 months' gestation. The probable cause of the fetus's death was
A) Fifth disease. B) Herpes simplex. C) Measles. D) Staphylococcus aureus. E) Streptococcus pyogenes. |
A
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Assume that your lab partner swabs the side of his face and used the swab to inoculate a nutrient agar plate. The next day, he performs a Gram stain on the colonies. They are gram-positive cocci. You advise him that he should next look for
A) An acid-fast reaction. B) A coagulase reaction. C) Conidiospores. D) Pseudohyphae. E) Pseudopods. |
B
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Which of the following pairs is mismatched?
A) Chickenpox – Poxvirus B) Conjunctivitis – Chlamydia trachomatis C) Keratitis – Acanthamoeba D) Infected tissue fluoresces – Dermatomycosis E) Buruli ulcer – Mycobacterium |
A
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A 17-year-old boy has pus-filled cysts on his face and upper back. Microscopic examination reveals gram-positive rods. This infection is caused by
A) Acanthamoeba. B) Herpes simplex virus. C) Propionibacterium acnes. D) Staphylococcus aureus. E) Streptococcus pyogenes. |
C
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Which of the following is NOT likely to spread MRSA among athletes?
A) Physical contact B) Whirlpool baths C) Taping gels D) Antibiotic resistance E) Shared equipment |
D
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CASE STUDY: WRESTLING WITH SKIN INFECTIONS
Background A wrestling camp held July 2 through July 28 was attended by 175 male high school wrestlers from throughout the United States. On July 19, seven wrestlers were referred to a local urgent care facility because of complaints of painful vesicles on various parts of their bodies [head or neck (3), extremities (2), trunk (1)] and conjunctiva (1). Bacterial and fungal cultures from the skin lesions were negative. A questionnaire was administered to wrestlers by telephone following the conclusion of camp. Sixty-one wrestlers met the case definition of the presence of cutaneous vesicles. Onset occurred during the camp session or within 1 week after the athletes left camp. Athletes who reported wrestling with a participant with a rash were more likely to have the infection. Thirty-eight wrestlers interviewed reported a past history of oral cold sores. The attack rate was 24% for wrestlers who reported a past history of oral cold sores and 38% for wrestlers without a history of oral cold sores. Questions 1. What diseases do you suspect? 2. How was this disease transmitted? 3. How is this disease treated? 4. Provide a possible explanation of the lower attack rate in wrestlers with a history of oral cold sores. 5. How can such outbreaks be prevented? |
1. Herpes gladiatorum
2. Direct contact 3. Acyclovir 4. Individuals with a history of oral herpes may have circulating antibodies that will prevent a new infection or recurrence. 5. Control methods should include education of athletes and trainers regarding herpes gladiatorum, routine skin examinations before wrestling contact, and exclusion of wrestlers with suspicious skin lesions. This outbreak might have been prevented if athletes with such lesions had been promptly excluded from contact competition. |
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A patient with urinary bladder infection was treated with nalidixic acid, but her condition did not improve. Explain why her infection disappeared when she switched to a sulfonamide
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The bacteria were resistant to nalidixic acid but susceptible to sulfonamide.
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A patient with streptococcal sore throat takes penicillin for 2 days of the prescribed 10 day regimen. Because he feels better, he then saves the remaining penicillin for some other time. After 3 more days, he suffers a relapse of the sore throat. Discuss the probable cause of the relapse.
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Many bacteria were killed initially, so the patient started to feel better. Recall that bacteria die logarithmically, so it takes quite a while to kill an entire population. The concentration of penicillin dropped in his body when he stopped taking penicillin, so the surviving bacteria were able to grow.
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Following is a case history of a 49 year old man. Identify each in the pattern of the disease that he experiences. On February 7th he handled a parakeet with a respiratory illness. On March 9, he experienced intense pain in his legs, followed by sever chills and headaches. On march 16th he had chest pain, cough, diarrhea and his temperature was 40C. Appropriate antibiotics were administered on march 17th and his fever subsided within 12 hours. He continued taking antibiotics for 14 days (Note the disease is Psittacosis. Can you find the etiology)
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February 7 to March 9: incubation period.
March 9: prodromal period. March 10 to March 17: period of illness. March 17: period of decline by crisis. Next 2 weeks: period of convalescence. Psittacosis is caused by Chlamydophila psittaci |
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Case Study
Background On October 15, a 40-year-old man was admitted to the hospital. He had a “splitting” headache, his legs were unsteady, and his vision was blurred. During examination, it was apparent that there was something wrong with his throat. It wasn’t sore, but it felt stiff and tight, and it was almost impossible for him to speak. Over the next 7 days, 28 persons with similar symptoms were admitted to the hospital. Twelve of these patients required ventilatory support; no deaths were reported. During the investigation, it became apparent that the illnesses were due to meals consumed between October 14 and 16 at one restaurant. Detailed food histories were obtained from the patients. An additional case-control study was conducted on well people who had consumed food at the restaurant during the same 3-day period. Repeated. news media announcements helped health personnel locate 18 other people who had eaten virtually the same foods at the restaurant. The meals consisted of the following foods: Patty Melt. Frozen hamburger patties purchased from a restaurant distributor. Patties were removed from the freezer and fried as ordered. Presliced pasteurized American cheese purchased from a distributor was kept refrigerated, and a slice was melted on each cooked hamburger patty. Meat and cheese were served on rye bread purchased from a local bakery. Sautéed Onions. Onions were purchased fresh from a farmer. Fresh whole onions were sliced and then sautéed with margarine, paprika, garlic salt, and a chicken-based powder. After the initial cooking, the onions were held uncovered in a pan on a warm stove (<60°C) along with a large volume of melted margarine; they were not reheated before serving. French-Fried Potatoes. Precut frozen potatoes were deep-fried in two- or three-serving batches as needed. Potato Salad. Potatoes were purchased from a farmer. They had been stored in a root cellar and were transported loose in a pickup truck. The potatoes were washed, peeled, diced, and boiled. Cooled, drained potato cubes were mixed with oil, vinegar, dry mustard, and garlic salt and were kept refrigerated. Individual servings were removed from the container as needed. Lettuce and Tomato Salad. Produce was delivered every other day. Lettuce and tomatoes were cut in the morning, refrigerated, and mixed with oil and vinegar for serving. Questions 1. On one page, identify the etiologic agent of this outbreak of food poisoning. 2. Was it food infection or intoxication? 3. What item was contaminated, and how did it become contaminated? 4. Briefly explain how you arrived at your conclusion. How did you eliminate the other major causes of food poisoning? Hints 1. Make a summary table of the persons not ill. 2. Make a table of the onset of symptoms following eating |
1. Clostridium botulinum.
2. Intoxication. 3. The onions were contaminated by C. botulinum from soil. 4. Of the 28 patients, 24 recalled eating the patty melt. All 24 patients, but only 10 of 18 controls, reported eating the sautéed onions. The original batch of sautéed onions was not available for culture or toxin testing, but type A botulinal toxin was detected in an extract made from washings of a discarded foil wrapper used by one of the patients to take a patty melt home. Type A botulinal spores were cultured from 5 of 75 skins of whole onions taken from the restaurant. No other ingredients of the sautéed onions contained toxin or spores. |
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CASE STUDY: DETERMINING THE METHOD OF ACTION
Background Assume you have discovered a new antibiotic. The effectiveness of this drug is shown below. To determine the method of action of this chemical, you culture a bacterium in two bioreactors containing nutrient broth, add the new drug to the test broth after 20 hours, and analyze both media. Protease activity is easily measured because protease is an extracellular enzyme. Data Antibiotic Disk Test Bacterium Zone of Inhibition (mm) Bacillus subtilis 0 Escherichia coli 10 Mycobacterium phlei 0 Pseudomonas aeruginosa 8 Salmonella typhimurium 9 Staphylococcus aureus 5 Streptococcus pyogenes 5 Questions 1. What bacterium did you use as your test organism? 2. Why were these particular parameters measured? What do they tell you about cell activity? 3. What is the method of action of this antibiotic? How can you tell? |
1. The test organism should be gram-negative because the drug is much less effective against gram-positives.
2. Cellular DNA is proportional to growth. Extracellular DNA indicates cells are lysing. The concentration of this protein is proportional to the rate of transcription. The concentration of NADH indicates the rate of catabolism. The rate of oxygen uptake is a measure of electron transport activity. 3. The decrease in protease suggests that protein synthesis is stopped. |
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CASE STUDY: AN OUTBREAK OF FOOD POISONING, SAN FRANCISCO
Background An outbreak of food poisoning occurred, affecting half the members of five families who ate at a restaurant in San Francisco at 3 p.m. on June 20. On June 20, a woman was admitted to a hospital with “chilliness,” nausea, abdominal cramps, and watery diarrhea. The next morning, she complained of limb numbness and difficulty swallowing and breathing. Examination was unremarkable except for slight weakness of the upper extremities and diminished deep tendon reflexes. Laboratory analysis yielded no viral or bacterial infection. An investigation was started to trace her contacts. During the investigation, it became apparent that the symptoms were due to a meal shared by 32 persons on June 20. The restaurant purchased rice from a produce market in a 50-kg bag. The rice was boiled the morning of the dinner and kept warm in foil-covered pots. Chicken was purchased from a supermarket. The chicken was cut up, browned in oil, and boiled for 2 hours; the flesh was pulled from the bones. The chicken was mixed with rice noodles. A whole, gutted pig was roasted in a conventional hot-air oven until the meat was white. Rice noodles were purchased from a supermarket, boiled, and pan-fried. Whole, ungutted jackfish were purchased from a seaman who caught the fish at Midway Island. The fish were frozen in the ship’s freezer until return to the Port of Oakland on June 19; they were gutted and cut into steaks, which were deep-fried and served in vinegar/herb sauce. The fish heads and viscera were boiled with vegetables for 15 minutes to make chowder (escabeche). Questions 1. On one page, identify the etiologic agent of this outbreak of food poisoning. 2. Was it food infection or intoxication? 3. How did the food get contaminated, and what item was contaminated? 4. Briefly explain how you arrived at your conclusion. How did you eliminate the other major causes of food poisoning? Hints 1. Make a summary table of the persons not ill. 2. Make a table of the onset of symptoms following eating. |
The Solution
1. Ciguatera poisoning. 2. Intoxication. 3. Ciguateratoxin is derived from the dinoflagellate Gambierdiscus toxicus, which herbivorous coral reef fish consume. Jackfish eat the herbivorous fish. 4. Diagnosis is clinical, based on the combination of gastrointestinal and neurological symptoms. The disease is endemic in many areas of the Caribbean and South Pacific. |
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CASE STUDY: FOOD POISONING, NEW MEXICO
Background The New Mexico Health Department was consulted by an Albuquerque physician regarding two patients, a husband and wife, who had become ill within 45 minutes of eating dinner. Their symptoms included nausea, vomiting, diarrhea, headache, fever, flushing, and rapid pulse rate. An investigation found that the couple had shared a meal of grilled mahi mahi, pasta, salad, water, and wine. In a hospital emergency room, both patients were treated with antihistamines and ipecac. Their symptoms resolved within 36 hours of the onset of illness. The fish had been imported from Taiwan through California and shipped frozen to the Albuquerque distributor, where it was thawed and sold from iced refrigerator cases. The patients had frozen the fish after they bought it. Later, they thawed it for 3 hours at room temperature and then grilled the still icy fish. Questions 1. Identify the etiologic agent of this outbreak of food poisoning. 2. Was it food infection or intoxication? 3. How did the food get contaminated, and what item was contaminated? 4. Briefly explain how you arrived at your conclusion. Data Food Eaten Husband Wife Daughter Dog Fish x x x Pasta x x x Salad x x x Wine x x x Water x x x x Ill Yes Yes No Yes |
The Solution
1. Scombroid fish poisoning. 2. Intoxication. 3. Of all varieties of fish, the scombroid species and certain other dark-meat fish are the most likely to develop high levels of histamine. When fresh scombroid fish are not continuously iced or refrigerated, bacteria may convert the amino acid histidine, which occurs naturally in the muscle of the fish, to histamine. Because histamine is resistant to heat, cooking the fish generally will not prevent illness. Histamine levels may not be correlated with any obvious signs of decomposition of the fish. Thus, prompt and proper refrigeration or icing from the time the fish is caught until it is preserved, processed, or cooked is essential to prevent scombroid fish poisoning. Antihistamines may be useful for symptomatic treatment. Because histamine is metabolized by intestinal microbiota, even large doses of ingested pure histamine usually do not cause symptoms. Thus, although histamine is a marker for fish that could cause scombroid fish poisoning, the actual mechanism for the poisoning must depend on an additional cofactor. Experimental evidence indicates that other substances produced in fish by putrefactive bacteria inhibit the metabolism of histamine and permit its absorption and circulation. 4. Recovery after treatment with antihistamines. Fish samples obtained from the store yielded histamine levels of 3 mg/100 g of sample. |
