Deck 19: Pathogenic Gram-Positive Bacteria

Question 1

Which of the following is NOT a feature of the pathogenesis of Clostridium perfringens?

A) cytotoxicity
B) reducing blood pressure
C) lysis of erythrocytes
D) edema due to increased vascular permeability
E) inhibiting sensory neuron function

Answer 1

E

Question 2

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

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

Answer 2

A

Question 3

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

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

Answer 3

B

Question 4

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

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

Question 5

Listeria virulence is directly related to its ability to

A) easily become a pathogen in humans.
B) produce powerful toxins.
C) form very resistant endospores.
D) resist most antimicrobial agents.
E) live within cells and thus avoid exposure to the immune system of its host.

Question 6

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

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

Question 7

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 have protein M in their capsule, which destabilizes complement and interferes with opsonization.
C) They grow in chains or pairs.
D) They have hyaluronic acid capsules.
E) They produce streptokinase, which breaks down blood clots.

Question 8

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

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

Question 9

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

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

Question 10

Which of the following streptococci is associated with dental caries?

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

Question 11

Which of the following bacteria can cause pharygitis?

A) Streptococcus pyogenes
B) Streptococcus anginosus
C) Streptococcus equisimilus
D) both Streptococcus equisimilus and S. pyogenes
E) Streptococcus anginosus, S. equisimilus, and S. pyogenes

Question 12

The Quellung reaction is used to diagnose

A) Streptococcus pyogenes.
B) Streptococcus agalactiae.
C) Staphylococcus aureus.
D) Streptococcus pneumoniae.
E) Streptococcus equisimilis.

Question 13

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

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

Question 14

Streptococci are frequently classified by

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

Question 15

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

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

Question 16

What differentiates virulent strains of Streptococcus pneumoniae from nonvirulent strains?

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

Question 17

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

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

Question 18

The pus from an abscess in a patient's jaw contains microbes that form yellowish grainy masses and appear filamentous under the microscope. Neither antifungal medication nor a normal course of antibiotics has been effective in treating the infection. The abscess is likely the result of infection with

A) Nocardia.
B) Actinomyces.
C) Propionibacterium.
D) Streptococcus.
E) Mycobacterium.

Question 19

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

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

Question 20

Which of the following statements about diphtheria is FALSE?

A) Its toxin destroys elongation factor, which is needed to synthesize polypeptides in eukaryotes.
B) Its growth on Loeffler's medium is used for absolute diagnosis of the bacterium.
C) Its toxin can be absorbed into the blood from cutaneous lesions and can lead to cardiac arrhythmia, coma, and death.
D) Although all species of Corynebacterium are pathogenic, the agent of diphtheria is the most widely known.
E) It produces a characteristic pseudomembrane that can adhere to the tonsils, uvula, palate, pharynx, and larynx.

Question 21

Mycoplasma pneumoniae causes respiratory disease by

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

Question 22

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

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

Question 23

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 one possible diagnosis?

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

Question 24

Untreated streptococcal pharyngitis may progress to

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

Question 25

The soil bacterium Nocardia asteroides can establish opportunistic infections of the

A) lungs.
B) cardiovascular system.
C) central nervous system.
D) skin.
E) skin, lungs, and central nervous system.

Question 26

Which of the following statements concerning tetanus is FALSE?

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

Question 27

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

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

Question 28

What clinical manifestation do Staphylococcus aureus and Staphylococcus epidermidis share?

A) hyaluronidase enzyme
B) staphylokinase
C) enterotoxins
D) nosocomial infections
E) protein A antiphagocytic factor

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

Question 30

Which of the following statements about Bacillus anthracis is FALSE?

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

Question 31

Infections with Streptococcus pyogenes may progress to _, characterized by a skin rash that peels after about a week and a bright red swollen tongue.

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

Question 32

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

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

Question 33

Which of the following statements regarding Streptococcus pyogenes is FALSE?

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

Question 34

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

Question 35

Which of the following has been historically classified as Gram- negative bacteria but is genetically more similar to low G + C Gram- positive bacteria?

A) Nocardia
B) Mycobacterium
C) Propionibacterium
D) Clostridium
E) mycoplasmas

Question 36

Under what conditions does infection with Mycobacterium leprae develop into tuberculoid leprosy?

A) when a strong antibody- mediated immune response develops
B) with pre- existing immunity as a result of immunization
C) in the absence of a cell- mediated immune response
D) when the immune system develops a vigorous cell- mediated response
E) when the innate respond is vigorous enough to clear the infection

Question 37

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

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

Question 38

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

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

Question 39

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

A) They have loosely organized polysaccharide slime layers.
B) They produce coagulase.
C) Cell division occurs in successively different planes, and the daughter cells remain attached to one another.
D) They produce staphylokinase, which dissolves fibrin threads in blood clots.
E) They produce fi- lactamase.

Question 40

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

Question 41

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

Question 42

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

Question 43

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

Question 44

Streptococcus agalactiae is associated with which of the following diseases?

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

Question 45

The aerobic endospore- former (Clostridium perfringens/Clostridium difficile/Bacillus anthracis) is a strict pathogen of humans and animals.

Question 46

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 47

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

Question 48

Streptococcus pneumoniae is a leading cause of

A) otitis media.
B) furuncles.
C) primary atypical pneumonia.
D) pharyngitis.
E) acne.

Question 49

The skin lesions characteristic of cutaneous infections with Bacillus anthracis are

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

Question 50

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

Question 51

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

Question 52

What is the most common disease caused by Propionibacterium?

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

Question 53

How does the toxin from Clostridium tetani produce its action?

A) It produces antibodies that attack the neuromuscular junctions in skeletal muscle and prevent them from relaxing.
B) It fuses irreversibly to neuronal cytoplasmic membranes, blocking release of acetylcholine at synaptic clefts.
C) The smaller polypeptide of its toxin can block the release of inhibitory neurotransmitters by inhibitory neurons in the central nervous system, causing simultaneous contraction of both muscles in an antagonistic pair.
D) It destroys tissues, including muscle and fat.
E) It is a pyrogenic toxin, which triggers a diffused rash and, later, sloughing of skin.

Question 54

The body limits the migration of Streptococcus (agalactiae/pneumoniae/pyogenes) by binding it to the active sites of secretory IgA, which the bacteria overcome by secreting secretory IgA protease.

Question 55

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

Question 56

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

Question 57

Successful treatment of diphtheria requires the administration of (antibiotics/antitoxin/immunoglobulin).

Question 58

The presence of mycolic acid in the cell walls of the opportunistic pathogen (Actinomyces/Nocardia) results in it Gram staining poorly.

Question 59

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

Question 60

(Enterococcus/Staphylococcus) grow at temperatures up to 45°C, at pH levels as high as 9.6, and in 6.5% NaCl, but they lack structural and chemical elements that make them virulent in the intestinal tract.

Question 61

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 from each other.

Question 62

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

Question 63

Enterococci have the ability to secrete bacteriocins, which inhibit the growth of other bacteria.

Question 64

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

Question 65

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

Question 66

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

Question 67

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 68

The respiratory infection known as "walking pneumonia" is caused by Mycoplasma pneumoniae.

Question 69

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

Question 70

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 is the culprit?

Question 71

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

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

In contrast to other mycobacteria, Mycobacterium avium- intracellulare simultaneously affects almost every organ in the body.

Question 74

Why would Clostridium botulinum be a good microorganism to use for biological warfare?

Question 75

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?