Deck 19: Pathogenic Gram Positive Bacteria

Question 1

Bacteria collected from a severely inflamed wound are sent to the lab for analysis.The results come back as follows: Gram-positive cocci in irregular clusters,kinase and coagulase positive,and able to grow in the presence of most antibiotics except vancomycin.The bacteria in the wound are most likely

A) Enterococcus.
B) Staphylococcus epidermidis.
C) Staphylococcus aureus.
D) methicillin-resistant Staphylococcus aureus (MRSA).
E) Streptococcus pyogenes (group A streptococcus).

Answer 1

D

Question 2

Otitis media may lead to dangerous meningitis in children due to infection with

A) Streptococcus agalactiae.
B) Streptococcus pneumoniae.
C) Streptococcus mutans.
D) Enterococcus.
E) Mycoplasma pneumoniae.

Answer 2

B

Question 3

Which of the following statements regarding Streptococcus pyogenes is FALSE?

A) It produces protein A, which inhibits opsonization.
B) It is beta-hemolytic.
C) It has group A Lancefield antigens.
D) It produces streptolysins.
E) It can be lysogenized by a temperate bacteriophage to produce erythrogenic toxins.

Answer 3

A

Question 4

Which of the following streptococci is associated with dental caries?

A) viridans streptococci
B) Streptococcus pyogenes
C) Streptococcus pneumoniae
D) Streptococcus equisimilis
E) Streptococcus arginosus

Question 5

Anthrax,which means "charcoal" in Greek,derives its name from

A) the airborne endospores it produces.
B) the staining properties of the bacillus under the microscope.
C) the black eschars it produces on human skin.
D) its ability to invade the bloodstream and produce toxemia.
E) the high mortality it causes in infected individuals.

Question 6

Which of the following staphylococcal virulence factors produce the signs and symptoms of scalded skin syndrome?

A) hyaluronidase
B) staphylokinase
C) exfoliative toxin
D) leukocidin
E) coagulase

Question 7

Which of the following diseases is considered an autoimmune disease triggered by bacterial infection?

A) glomerulonephritis caused by the group A streptococci
B) scarlet fever
C) rheumatic fever
D) impetigo
E) toxic shock syndrome

Question 8

The presence of ________ can be used to distinguish Staphylococcus from other Gram-positive cocci.

A) enterotoxins
B) catalase enzyme
C) protein M
D) kinases
E) hemolysins

Question 9

Which of the following is an antiphagocytic factor of Staphylococcus?

A) protein A
B) catalase
C) hemolysin
D) protein M
E) hyaluronidase

Question 10

A woman comes to the emergency department with fever and vomiting.She soon develops a red rash all over her body,and her blood pressure begins to drop.What is a likely diagnosis?

A) erysipelas
B) endocarditis
C) scarlet fever
D) toxic shock syndrome
E) staphylococcal food poisoning

Question 11

Streptococci are frequently classified by

A) Lancefield antigen designations.
B) the type of enzymes the bacteria produce.
C) their staining properties.
D) their ability to produce a capsule.
E) the diseases they produce.

Question 12

What differentiates virulent strains of Streptococcus pneumoniae from nonvirulent strains?

A) the species-specific teichoic acid present in its cell wall
B) the type of Lancefield antigen it produces
C) the presence of a polysaccharide capsule
D) the type of toxins it produces
E) the extent of the hemolytic zone it produces when it is grown on blood agar

Question 13

Untreated streptococcal pharyngitis may progress to

A) scarlet fever.
B) necrotizing fasciitis.
C) rheumatic fever.
D) scarlet fever or necrotizing fasciitis.
E) scarlet fever or rheumatic fever.

Question 14

How do group A streptococci camouflage themselves from white blood cells?

A) they produce coagulase, allowing the bacteria to hide within blood clots.
B) they grow in chains or pairs.
C) they produce streptokinase, which breaks down blood clots.
D) they have hyaluronic acid capsules.
E) they have a coating of protein M.

Question 15

Which of the following statements about "flesh-eating" streptococci is FALSE?

A) It is caused by a group A streptococcus.
B) It is also known as necrotizing fasciitis because it travels along the fascia.
C) It causes death in over 50% of cases.
D) It is considered a common complication of pyoderma.
E) It involves toxemia.

Question 16

Over 90% of Staphylococcus aureus isolates are penicillin-resistant.Why?

A) they have loosely organized polysaccharide slime layers which protects their cell wall.
B) they produce coagulase.
C) They have a coating of protein A.
D) they produce β-lactamase.
E) they produce staphylokinase.

Question 17

During a stay in the hospital,an accident victim develops symptoms of bacteremia.A blood sample shows the presence of Gram-positive cocci in pairs.Lab tests determine that the bacteria are nonhemolytic and bile salt tolerant.The bacteremia is likely due to

A) Enterococcus.
B) Mycoplasma.
C) Staphylococcus.
D) Streptococcus.
E) Listeria.

Question 18

The Quellung reaction is a test to detect

A) hemolysins.
B) kinases.
C) pyrogens.
D) capsule antigens.
E) protein M.

Question 19

What is one virulence factor that differentiates Staphylococcus aureus from other species of staphylococci?

A) It has a capsule.
B) It can produce coagulase.
C) It produces catalase.
D) it can live on the surface of the skin and in cutaneous oil glands.
E) it produces lipase.

Question 20

Streptococcus agalactiae is associated with which of the following diseases?

A) neonatal bacteremia
B) neonatal meningitis
C) neonatal pneumonia
D) both neonatal bacteremia and neonatal meningitis
E) neonatal bacteremia, neonatal meningitis, and neonatal pneumonia

Question 21

Which of the following statements about diphtheria is FALSE?

A) All species of Corynebacterium may be pathogenic.
B) Its toxin interferes with eukaryotic protein synthesis.
C) It produces a characteristic pseudomembrane that can adhere to tissues in the throat.
D) Its growth on Loffler's medium is used for absolute diagnosis of the bacterium.
E) Its toxin can be absorbed into the blood from cutaneous lesions leading to severe complications.

Question 22

What is the most common disease caused by Propionibacterium?

A) acne
B) food poisoning
C) pneumonitis
D) folliculitis
E) a sty

Question 23

Mycobacterium leprae primarily infects

A) macrophages.
B) skin cells.
C) neurons.
D) macrophages and skin cells.
E) skin cells and neurons.

Question 24

Which of the following statements concerning tetanus is FALSE?

A) Its only source is from deep puncture wounds from rusty nails.
B) Its toxin causes simultaneous contraction of both muscles in an antagonistic pair.
C) It is a small, motile, obligate anaerobe.
D) It produces a terminal endospore that gives the cell a distinctive "lollipop" appearance.
E) Its diagnostic feature is characteristic muscle contractions, which are often noted too late to save the patient.

Question 25

The skin lesions characteristic of cutaneous infections with Bacillus anthracis are

A) eschars.
B) acne.
C) impetigo.
D) scarlatina.
E) pus-filled ulcers.

Question 26

Which of the following bacteria can cause life-threatening pseudomembranous colitis?

A) Clostridium difficile
B) Staphylococcus aureus
C) Streptococcus pyogenes
D) Enterococcus species
E) Clostridium botulinum

Question 27

Mycetoma,which is a painless long-lasting infection characterized by swelling,pus production,and draining sores,is commonly caused by

A) systemic tuberculosis.
B) Nocardia.
C) Actinomyces.
D) penicillin-resistant staphylococci.
E) cutaneous anthrax.

Question 28

Enterococcus faecalis bacteria can be distinguished from other Gram-positive cocci because enterococci

A) have a glycocalyx.
B) produce catalase enzyme.
C) produce hemolysins.
D) can grow in the presence of bile salts.
E) are highly sensitive to antibiotics.

Question 29

A sample of fluid from the lungs contains microbes that grow in filaments or clumps.The cells stain poorly in the Gram stain and are a pink-red when acid-fast stained.The bacteria in the sample are

A) Mycobacterium species.
B) Mycoplasma species.
C) Nocardia species.
D) Actinomyces species.
E) not identifiable with this information.

Question 30

Increased sebum secretion can fuel the overgrowth of the opportunistic pathogen ________ in its normal habitat,leading to disease.

A) Propionibacterium acnes
B) Streptococcus agalactiae
C) viridians streptococci
D) Mycoplasma pneumoniae
E) Actinomyces

Question 31

How does the toxin from Clostridium tetani produce its action?

A) it fuses irreversibly to neurons, blocking release of acetylcholine at synaptic clefts.
B) the smaller polypeptide of its toxin can block the release of inhibitory neurotransmitters by inhibitory neurons in the central nervous system.
C) it is a pyrogenic toxin, which triggers a diffused rash and, later, sloughing of skin.
D) it destroys tissues, including muscle and fat.
E) Antibodies to the toxin bind the neuromuscular junctions in skeletal muscle preventing relaxation.

Question 32

The pathogenicity of primary tuberculosis is due to the fact that the mycobacteria

A) are not phagocytized.
B) prevent fusion of lysosomes with vesicles.
C) form a pseudomembrane.
D) destroy helper T cells.
E) are carried by macrophages to a variety of sites.

Question 33

A lab report on a respiratory patient's sample contains the notation MDR-TB.What does this mean?

A) The two standard drugs for TB, isoniazid and rifampin, are not effective.
B) The patient has a mild case of TB.
C) There are almost no drugs that will treat the infection.
D) Most standard drugs for treatment of TB are recommended.
E) The bacteria responsible for the infection are moderately resistant to isoniazid and rifampin.

Question 34

Which of the following bacteria divide by "snapping division" in which daughter cells remain attached in characteristic V-shapes?

A) staphylococci
B) enterococci
C) Corynebacterium
D) Listeria
E) Mycobacterium

Question 35

Which of the following statements about Bacillus anthracis is FALSE?

A) It is primarily a disease of humans.
B) It produces endospores.
C) It has a capsule.
D) It normally dwells in the soil and can survive in the environment for centuries or longer.
E) It can be lethal even after treatment because antimicrobial drugs do not inactivate accumulated anthrax toxin.

Question 36

An opportunistic pathogen frequently seen in AIDS patients,________ spreads rapidly to various organs.

A) Mycobacterium tuberculosis
B) Mycobacterium avium-intracellulare
C) Mycobacterium leprae
D) Mycobacterium bovis
E) Mycobacterium ulcerans

Question 37

Listeria virulence is directly related to its ability to

A) produce powerful toxins.
B) form very resistant endospores.
C) live within cells and thus avoid exposure to the immune system of its host.
D) move rapidly through the body using multiple flagella.
E) resist most antimicrobial agents.

Question 38

Strep throat may progress to ________,characterized by a skin rash and a bright red swollen tongue.

A) pyoderma
B) toxic shock syndrome
C) scarlet fever
D) rheumatic fever
E) scalded skin syndrome

Question 39

Which of the following bacteria produce one of the most deadly bacterial toxins known?

A) Clostridium perfringens
B) Clostridium difficile
C) Clostridium tetani
D) Clostridium botulinum
E) Corynebacterium species

Question 40

Members of the genus Mycoplasma are pleomorphic and stain Gram-negative because they

A) lack cell walls.
B) have sterols in their cytoplasmic membranes.
C) lack cytoplasmic membranes.
D) have mycolic acid in their cell walls.
E) have a rudimentary cell wall.

Question 41

Adult foodborne botulism can be prevented by thoroughly cooking food (minimum 80°C for 20 minutes)before it is eaten.

Question 42

The primary reservoir of anthrax is herbivores.

Question 43

Which of the following is a key diagnostic indicator of infection with Mycobacterium leprae?

A) blister-like lesions
B) a distinctive red rash that lasts for days
C) pus-filled abscesses
D) localized loss of the sense of touch
E) severe inflammation with swelling

Question 44

Immunization for ________ may reduce the incidence of otitis media and sinusitis.

A) Mycoplasma pneumoniae
B) Mycobacterium tuberculosis
C) Propionibacterium acnes
D) Corynebacterium diphtheriae
E) Streptococcus pneumoniae

Question 45

In its role in the development of acne,(Propionibacterium/Staphylococcus/Actinomyces)typically grows in sebaceous glands of the skin.

Question 46

The respiratory infection known as primary atypical pneumonia is caused by Mycoplasma pneumoniae.

Question 47

(MRSA/MDR-TB/VRSA)is resistant to numerous antimicrobial agents; therefore,vancomycin is usually used for these infections.

Question 48

Mycoplasma pneumoniae causes respiratory disease by

A) infecting and killing alveolar macrophages.
B) triggering inflammatory mediator release.
C) attaching to and ultimately killing the ciliated epithelial cells of the trachea.
D) paralyzing the respiratory muscles.
E) killing the epithelial cells of the alveoli.

Question 49

Staphylococcus aureus can produce a toxin that dissolves the desmosomes that hold the adjoining cytoplasmic membranes of cells together and causes the patient's skin cells to separate.

Question 50

Mycobacterium tuberculosis is able to persist and be spread in aerosols due to its ability to produce endospores.

Question 51

A "summer cold" that lasts for weeks and is characterized by sore throat,mild fever,dry cough,and malaise may be (pneumococcal/staphylococcal/walking)pneumonia.

Question 52

A person comes into the clinic with a wound that is severely inflamed,very painful,and turning black and "bubbly." The diagnosis is leprosy.

Question 53

The primary treatment for food-borne botulism is (antibiotics/antitoxin/muscle relaxants).

Question 54

Painful swelling and rapidly spreading subcutaneous tissue necrosis is characteristic of a wound infection by

A) Clostridium perfringens.
B) Clostridium tetani.
C) Mycobacterium leprae.
D) Bacillus anthracis.
E) Clostridium difficile.

Question 55

The bacterium Streptococcus mutans has a major role in the development of dental plaque and caries.

Question 56

Staphylococcus aureus food poisoning is long-lasting because ingested bacteria produce enterotoxins in the digestive system.

Question 57

Group A streptococci are considered more virulent if their cytoplasmic membrane contains M protein.

Question 58

Eating food contaminated with ________ may result in meningitis in at-risk persons.

A) Mycoplasma hominis
B) Staphylococcus aureus
C) Listeria monocytogenes
D) Clostridium perfringens
E) Enterococcus faecalis

Question 59

In countries where tuberculosis is common,people are vaccinated with (BCG/INH/MDR-TB),which contains attenuated Mycobacterium bovis bacteria.

Question 60

Streptococcus pyogenes commonly causes streptococcal toxic shock syndrome in otherwise healthy people.

Question 61

A large number of patrons of a restaurant in a large city develop symptoms of food poisoning.Officials collect several foods that are suspected in the episode.Which of the Gram-positive bacteria in this chapter may be responsible for the food poisoning? How do health officials determine which bacterium is the culprit?

Question 62

Members of the genus (Bacillus/Enterococcus/Mycobacterium)are part of the normal microbiota of humans.

Question 63

Common sources of Listeria are undercooked meats and vegetables and unpasteurized (eggs/soft cheeses/juices).

Question 64

A throat swab is taken from a patient with a respiratory infection.After 24 hours,1- to 3-mm colonies develop,which are round,mucoid,nonpigmented,and dimpled in the middle.What is the most likely pathogen,and how could you confirm the diagnosis on the culture?

Question 65

Mycobacterium leprae infections manifest in two different forms in a patient.What are these? What determines which form the patient will develop?

Question 66

When observed in the lab Mycoplasma stains (acid-fast/Gram-positive/Gram-negative).

Question 67

Infection with Corynebacterium diphtheriae leads to the formation of (eschars/pseudomembranes/tubercles)which can severely impair respiratory function.

Question 68

The ability to produce (hyaluronidase/lipase/proteases)enables Staphylococcus aureus to penetrate and spread through tissues.

Question 69

Would Clostridium botulinum be a good microorganism to use for biological warfare? Explain.

Question 70

When streptococcal infections involve the skin and surrounding lymph nodes,triggering pain and inflammation,the condition is known as (erysipelas/folliculitis/pyoderma).

Question 71

Streptococcus pyogenes produces (hemolysin/protein A/M protein)and thereby avoids phagocytosis.

Question 72

Compare and contrast the pathogenicity of Clostridium botulinum and Clostridium tetani,including mechanisms of action of their toxins and disease manifestations.

Question 73

The bacterium Clostridium (botulinum/difficile/perfringens)is an opportunistic pathogen that can cause a severe,potentially fatal diarrhea.

Question 74

Bacterial food poisoning resulting from Clostridium (botulinum/difficile/perfringens)contamination is characterized by watery diarrhea accompanied by intestinal cramping but not fever,and it resolves in about a day.

Question 75

The neurotoxins of Clostridium botulinum produce (flaccid/tetanic)paralysis by preventing muscle contraction.