MMID Exam 2 - October 29 2004

A child is brought to the emergency room with a fever of 102F. She has a moderately red throat with white to yellow-gray tonsillar patches, a clear chest, and bilaterally enlarged cervical lymph nodes. Because her throat culture is positive for Group A Streptococcus, she is treated with amoxicillin at home. However, she continues to get worse, and 4 days later she returns because she is having trouble breathing and is admitted to the hospital. A grayish-white membrane is found in her throat, and although a tracheotomy is performed the child dies.

Question 1 - Single Best Answer

What is the likely cause of the childÕs death?

A) fluid in her lungs
B) heart failure due to cellular death
C) sepsis and total organ failure
D) suffocation
E) heart failure due to autoimmune reaction

(Same case from previous question repeated for clarity.) A child is brought to the emergency room with a fever of 102F. She has a moderately red throat with white to yellow-gray tonsillar patches, a clear chest, and bilaterally enlarged cervical lymph nodes. Because her throat culture is positive for Group A Streptococcus, she is treated with amoxicillin at home. However, she continues to get worse, and 4 days later she returns because she is having trouble breathing and is admitted to the hospital. A grayish-white membrane is found in her throat, and although a tracheotomy is performed the child dies.

Question 2 - Single Best Answer

The production of the factor that killed her is an example of

A) spontaneous point mutation
B) generalized transduction
C) specialized transduction
D) lysogenic conversion
E) transformation

Question 3 - Single Best Answer

Which of the following diseases is caused by a bacterium that synthesizes dipicolinic acid as part of its pathogenic life cycle?

A) tuberculosis
B) diphtheria
C) anthrax
D) pneumococcal pneumonia
E) mycoplasma pneumonia

Question 4 - Single Best Answer

The genetic information for chloramphenicol acetyl transferase is most likely to reside on:

A) the chromosome
B) a plasmid
C) a lytic phage
D) a prophage
E) a therapeutic phage

Question 5 - Single Best Answer

A correctly obtained (adequate) sputum sample obtained from a patient with LegionnaireÕs disease will:

A) be rust colored
B) be bloody
C) have lots of squamous epithelial cells
D) contain Gram positive diplococci
E) be thin and watery with few bacteria visible

Question 6 - Single Best Answer

Which of the following bacterial transport methods is energy independent?

A) group translocation
B) facilitated diffusion
C) LacY permease transport of lactose
D) active transport
E) None of the above.

Question 7 - Single Best Answer

A child with a red, sore throat is treated with amoxicillin and clavulanic acid. The direct purpose of the clavulanic acid is to:

A) inhibit transpeptidation
B) reduce the inflammation and make the child feel better
C) kill any bacteria that might become resistant to amoxicillin during the course of the treatment.
D) to inhibit an enzyme that can break down amoxicillin
E) inhibit the transport of the peptidoglycan building block

Question 8 - Single Best Answer

A throat swab is done on an adult with pharyngitis. Many alpha-hemolytic colonies that are optochin-sensitive are isolated. The presence of these colonies means the patient has:

A) pneumonia
B) Strep throat
C) meningitis
D) otitis media
E) None of the above.

Question 9 - Single Best Answer

Acute glomerulonephritis after Group A streptococcal infection can be associated with each of the following EXCEPT:

A) streptococcal pharyngitis.
B) streptococcal skin infection.
C) immune damage to the kidney.
D) streptococcal infection of the kidney.
E) elevated or rising antibodies to DNAse B or streptolysin O

Question 10 - Single Best Answer

If you were going to design a new drug to act on Corynebacterium diphtheriae to inhibit its virulence, which of the following activities would represent the best target?

A) production of capsule
B) production of endotoxin
C) adenylate cyclase
D) ADP-ribosyl transferase
E) elongation factor 2 (EF-2)

Question 11 - Single Best Answer

Inhibition of which of the following explains why people are generally more susceptible to bacterial pneumonia after experiencing viral respiratory infections?

A) alveolar macrophages
B) mucosal IgA
C) serum IgG
D) mucociliary escalator
E) alveolar complement

Question 12 - Single Best Answer

A major virulence factor for Streptococcus pyogenes that is a known target of protective immunity is:

A) capsule.
B) peptidoglycan.
C) M protein.
D) Streptolysin O.
E) erythrogenic toxin.

Question 13 - Single Best Answer

A patient in the burn unit develops a fever. When his bandages are changed, it is noticed that they give off a ÒfruityÓ odor and that the pus is greenish colored. Which of the following is the most likely source of the bacteria infecting his burns?

A) the anterior nares of the nursing staff
B) the hands of the doctor
C) the water in the saucer under the plant his wife gave him
D) his pharynx
E) his intestinal tract

Question 14 - Single Best Answer

The major difference between fermentation and aerobic respiration in bacteria is that:

A) in fermentation an organic compound is reduced and NAD is oxidized. In respiration oxygen is reduced and NAD is oxidized.
B) in respiration an organic compound is reduced and NAD is oxidized, while in respiration CO2 is oxidized and O2 is reduced.
C) in fermentation, pyruvic acid is oxidized to lactic acid, while NAD is reduced. In respiration nitrate is reduced and NADH2 is oxidized
D) in fermentation an organic compound is reduced and NADH2 is oxidized. In respiration oxygen is reduced and NADH2 is oxidized.

Question 15 - Single Best Answer

Putting antibiotics in animal feed is a bad idea because:

A) there wonÕt be enough for all of the cases of influenza that occur as a result of no flu vaccine.
B) the antibiotics will cause mutations in the ribosomes that will make the bacteria resistant so antibiotics will not be curative for animal diseases.
C) the antibiotics will cause transposons to jump from the chromosome to plasmids and become transferable.
D) the antibiotics will select for resistant bacteria that may contaminate meat or milk for human consumption.
E) None of the above. Providing antibiotics in animal feed has resulted in no adverse consequences, in fact, halting this process would destroy the agriculture of the United States.

Question 16 - Single Best Answer

A bronchopneumonia pattern on a chest X-ray is indicative of each of the following EXCEPT:

A) Streptococcus pneumoniae
B) Staphylococcus aureus
C) Mycoplasma pneumoniae
D) Chlamydia pneumoniae
E) Viral pneumonia

Question 17 - Single Best Answer

The best way to administer steroids in treating septic shock is:

A) high dose, short course.
B) low dose, long course.
C) orally before admission to the hospital.
D) topically at the site of infection.
E) None of the above - steroids are counter productive.

Question 18 - Single Best Answer

Ear pain due to myringitis is likely to accompany pneumonia that:

A) is caused by an alpha hemolytic organism.
B) is transmitted to humans from parrots.
C) is due to an obligate intracellular organism.
D) is due to a naturally penicillin-resistant organism.
E) is not contagious from person-person.

Question 19 - Single Best Answer

A rapid test to confirm LegionnaireÕs disease is to:

A) see if the organism was transmitted to a family member.
B) look for IgA in the patientÕs lung secretions.
C) look for Legionella antigen in the urine.
D) grow the organism from the sputum on blood agar.
E) look for calcifications on a chest X-ray.

Question 20 - Single Best Answer

The reservoir for Legionella pneumophila is:

A) anterior nares of humans.
B) humans who have had Pontiac Fever.
C) parrots.
D) water sources containing amoeba.
E) water sources contaminated with urine and fecal matter

Question 21 - Single Best Answer

Sickle-cell anemia is a risk factor for pneumococcal pneumonia because:

A) the bacterium grows better in the blood due to the greater availability of iron.
B) the mutation that causes the anemia also causes decreased ciliary activity.
C) sickle-cell anemics are functionally asplenic.
D) sickle-cell anemics do not have functional alveolar macrophages.
E) sickle-cell anemics are more likely to be colonized by anaerobic bacteria because of the decreased ability to transport O2.

Question 22 - Single Best Answer

A 55 year old man has night sweats, chronic cough, weight loss, and fatigue. If acid-fast bacteria are observed in his sputum, another likely characteristic of the sputum would be:

A) rust color of hemolyzed blood
B) thin and watery
C) frank blood (hemoptysis)
D) lots of squamous epithelial cells
E) current jelly consistency and color

Question 23 - Single Best Answer

Which of the following best describes the pathogenesis of acute rheumatic fever?

A) It is characterized by inflammation of the heart and/or the joints.
B) It is due to an immunologic cross reaction between heart muscle and Staphylococcus aureus.
C) Prophylaxis with antibiotics is of little value.
D) It is a complication of Group A streptococcal skin disease as well as pharyngitis.
E) It involves beta-hemolytic Streptococci growing in the heart.

Question 24 - Single Best Answer

Which of the following are direct consequences of gram-negative cell wall structure?

A) Gram-negative bacteria are resistant to beta-lactams and produce no capsules.
B) Gram-negative bacteria are resistant to lysis by complement and produce no capsules.
C) Gram-negative bacteria are resistant to vancomycin and sensitive to lysis by complement
D) Gram-negative bacteria b cannot be cultured on media with bile salts and are resistant to beta-lactam antibiotics
E) Gram-negative bacteria are resistant to polymyxin antibiotics and are sensitive to bacitracin

Question 25 - Single Best Answer

A surface protein of a bacterial cell binds host factor H. A direct consequence of this would be:

A) decrease in activated complement on the cell surface.
B) increase in intracellular growth rate.
C) autoimmune reaction.
D) resistance to beta-lactams
E) invasion through host tissues

Question 26 - Single Best Answer

Which of the following most likely has a pentaglycine bridge in its peptidoglycan?

A) Escherichia coli
B) Klebsiella pneumonia
C) Mycoplasma pneumonia
D) Staphylococcus aureus
E) Bordetella pertussis

Question 27 - Single Best Answer

The normal role for penicillin binding proteins is to:

A) inactivate beta-lactam antibiotics.
B) transport beta-lactam antibiotics out of the cell.
C) produce beta-lactam antibiotics.
D) inactivate beta-lactamase in conjunction with a beta-lactam antibiotic.
E) None of the above.

Question 28 - Single Best Answer

The unique fatty acid component of lipopolysaccharide is called:

A) Beta-hydroxy-myristic acid
B) Wax D
C) Polymyxin
D) Lipoteichoic acid
E) Muramic acid

Question 29 - Single Best Answer

Which of the following represents the least likely source for targets for developing new antibacterial drugs?

A) Lipopolysaccharide
B) Cytoplasmic/inner membrane
C) Ribosomes
D) RNA polymerase
E) Wax D

Question 30 - Single Best Answer

Which of the following best describes why sulfa drugs and trimethoprim are effective antibiotics?

A) Although humans have the target for sulfa drugs, it is different from bacteria; humans lack the target of trimethoprim.
B) Humans lack the target of sulfa drugs; although humans have the target for trimethoprim, it is different from bacteria.
C) Humans lack the targets for both trimethoprim and sulfa drugs.
D) Although humans have the targets for sulfa drugs and trimethoprim, they are different from that of bacteria.
E) None of the above.

Question 31 - Single Best Answer

Microbial glycocalyx would most likely be associated with:

A) Planktonic bacteria
B) Bacteriophage
C) Viruses
D) Biofilms
E) None of the above.

Question 32 - Single Best Answer

Single point mutations in bacteria are likely to result in all of the following EXCEPT:

A) no visible change (silent)
B) change in amino acid sequence (missense)
C) stop codon (nonsense)
D) failure of an antibiotic to bind to its target
E) degradation of an antibiotic

Question 33 - Single Best Answer

The major difference between lysogenic conversion and specialized transduction is:

A) the gene in question is normally phage-encoded versus bacterially encoded.
B) if the host cell is gram-positive versus gram-negative.
C) if the phage is lytic versus temperate.
D) if a plasmid is involved versus uptake of naked DNA.
E) if a virulence gene versus antibiotic resistance gene is transferred.

Question 34 - Single Best Answer

A 5 year old boy presents with pharyngitis and a fever of 102F. He also has a runny nose, is coughing, and is hoarse. These latter symptoms most likely mean that:

A) the patient will experience poststreptococcal rheumatic fever.
B) the patient will experience poststreptococcal glomerulonephritis.
C) the patient will experience scarlet fever.
D) the patient has Sydenham's chorea
E) None of the above.

Question 35 - Single Best Answer

The most important role of integrons in bacteria is:

A) invasion of host cells.
B) invasion through tissues.
C) acquisition of DNA sequences.
D) conjugation of plasmids.
E) acquisition of iron from the host.

Question 36 - Single Best Answer

A site-specific recombination between two inverted repeats of DNA flanking a gene would most likely cause:

A) Transformation
B) Turning the gene on or off.
C) Lysogenic conversion
D) Changing between numerous (>3) forms of the gene
E) Generalized transduction

Question 37 - Single Best Answer

Which of the following best describes the relation between vancomycin and ampicillin?

A) Vancomycin binds the enzyme, ampicillin binds the substrate.
B) Ampicillin binds the enzyme, vancomycin binds the substrate.
C) Vancomycin is bacteriostatic, ampicillin is bactericidal.
D) Ampicillin is bacteriostatic, vancomycin is bactericidal.
E) None of the above. Both antibiotics have the same mechanisms of action on peptidoglycan.

Question 38 - Single Best Answer

Adding radioactive isoleucine will result in its incorporation and accumulation into amino acids. Each of the following will cause a decrease in accumulation of radioactive isoleucine when added to an antibiotic-sensitive bacterial culture EXCEPT:

A) Rifampin
B) Chloramphenicol
C) Tetracycline
D) Mupirocin
E) Clavulanic acid

Question 39 - Single Best Answer

Methicillin resistant Staphylococcus aureus are resistant to methicillin because:

A) they have acquired a plasmid encoding beta-lactamase.
B) they are accumulating point mutations in penicillin binding proteins.
C) they are acquiring transposons as a result of antibiotics in animal feed.
D) they acquired resistant penicillin binding protein genes by genetic exchange.
E) they modify the penicillin binding proteins with an enzyme from a plasmid.

Question 40 - Single Best Answer

Normal bacterial flora:

A) never cause disease.
B) only cause disease in immunocompromised hosts.
C) are present in a significant proportion of healthy people.
D) are only found in the intestinal tract and respiratory tract.
E) have no benefit to the host.

Question 41 - Single Best Answer

Endogenous infections/diseases are different from exogenous infections/disease in that:

A) Endogenous must spread, by definition, whereas exogenous are superficial.
B) Endogenous are intracellular, while exogenous are extracellular
C) Endogenous are cause by bacteriophage, while exogenous are caused by bacteria.
D) Endogenous result after a significant, stable relationship, whereas exogenous initiate the disease process almost immediately upon the encounter
E) Endogenous are from human only reservoirs, while exogenous are from animal only reservoirs.

Question 42 - Single Best Answer

Pili or fimbriae are most often directly associated with which step of pathogenesis?

A) Entry
B) Multiplication
C) Damage
D) Spreading through tissues
E) Evasion of host defenses

Question 43 - Single Best Answer

The difference between antigenic cloaking and antigenic mimicry is:

A) Cloaking is a carbohydrate, mimicry is a protein.
B) Mimicry is a carbohydrate, cloaking is a protein.
C) Cloaking is a host antigen, mimicry is a bacterial antigen.
D) Mimicry is a host antigen, cloaking is a bacterial antigen.
E) None of the above Ð the terms are synonymous.

Question 44 - Single Best Answer

LipopolysaccharideÕs toxic activity is the result of:

A) apoptosis of macrophages.
B) lysis of macrophages.
C) inhibition of protein synthesis.
D) ADP ribosylation
E) stimulation of cytokines by host cells.

Question 45 - Single Best Answer

In which of the following specimens would use of selective plates be most important?

A) Blood
B) Cerebrospinal fluid
C) Feces
D) Pleural effusion
E) None of the above Ð selective plates are not used anymore in the microbiology laboratory.

Question 46 - Single Best Answer

Which of the following would NOT be identifiable by Gram stain?

A) Staphylococcus aureus
B) Streptococcus pneumoniae
C) Mycobacterium tuberculosis
D) Escherichia coli
E) All of the above could be identified by Gram stain.

Question 47 - Single Best Answer

What do diphtheria toxin and pertussis toxin have in common?

A) cause increase in cAMP
B) inhibit protein synthesis
C) ADP-ribosylating activity
D) lysis of host cells
E) only act locally at site of production during disease

Question 48 - Single Best Answer

Anti-toxin antibodies are part of the treatment for:

A) Tuberculosis
B) Diphtheria
C) Whooping cough
D) Rheumatic fever
E) Staphylococcal pneumonia

Question 49 - Single Best Answer

The highest levels of bacteria during whooping cough are during:

A) the incubation period.
B) the catarrhal phase.
C) the paroxysmal phase.
D) the convalescent phase.
E) the post-antibiotic phase.

Question 50 - Single Best Answer

Which of the following is LEAST likely to cause long-term or permanent damage to the lower respiratory tract?

A) Staphylococcus aureus
B) Klebsiella pneumoniae
C) Mycobacterium tuberculosis
D) Streptococcus pneumoniae
E) None of the above Ð all of the agents cause equally destructive tissue damage in the lungs.

Question 51 - Single Best Answer

Which of the following pairs of diseases would you expect to have the most similar form of effective protective immunity?

A) Pneumococcal pneumonia and LegionnaireÕs disease
B) Mycoplasma pneumonia and tuberculosis
C) LegionnaireÕs disease and tuberculosis
D) Diphtheria and tuberculosis
E) None of the above. There is no relationship between type of infection and protective immunity.

Question 52 - Single Best Answer

Given that mycoplasmas lack cell walls, what compensatory mechanism do these bacteria use to survive?

A) Incorporating sterols in their cell membrane
B) Having a thick peptidoglycan layer
C) Having long O-antigen
D) Producing a thick polyglutamate capsule
E) Having a tough fibrillar layer

Question 53 - Single Best Answer

Each of the following is a sign of severe sepsis EXCEPT:

A) temperature >38C or <36C
B) Heart rate >90 bpm
C) Respiratory rate >20 bpm
D) Hypotension that does not respond to fluids
E) WBC >12,000, WBC <4,000, or bands >10%

Question 54 - Single Best Answer

Which of the following best describes the initiation of the host response to microbial antigens leading to sepsis?

A) Invasion of host cells by bacteria resulting in cell death
B) Secretion of toxins by bacteria that stimulate apoptosis
C) Binding of microbial products to Toll-like receptors and transmembrane signalling
D) Production of antibodies by B cells and cytokines by T cells
E) Activation of complement followed by disseminated intravascular coagulation and diapedesis of phagocytes

Question 55 - Single Best Answer

The most important intervention in preventing septic shock is timely administration of:

A) antibiotics and fluids.
B) monoclonal antibodies against bacterial products such as LPS.
C) monoclonal antibodies against cytokines.
D) activated protein C.
E) drugs that increase the plasma pH.

Question 56 - Single Best Answer

Which of the following symptoms is most likely to be present in a patient a the time of a positive anti-Streptolysin O (ASO) test?

A) sore throat
B) sandpaper rash
C) doughnut lesions in the pharynx
D) migratory polyarthritis
E) strawberry tongue

Question 57 - Single Best Answer

Complications of pertussis include each of the following EXCEPT:

A) myocarditis.
B) pneumonia.
C) apnea.
D) seizures.
E) encephalopathy.

Question 58 - Single Best Answer

Which of the following is NOT directly preventable by vaccination?

A) pertussis
B) pneumococcal pneumonia
C) post streptococcal rheumatic fever
D) diphtheria
E) influenza pneumonia

Question 59 - Single Best Answer

Some hospital laboratories will not culture a sputum sample with >10 squamous epithelial cells per low power field because:

A) this is a sign of lack of disease.
B) this is a sign of viral infection.
C) epithelial cells secrete defensins that kill bacteria in the sample.
D) the sample is contaminated with oral secretions.
E) None of the above Ð such a sample would be cultured because the epithelial cells confirm bacterial pneumonia.

Question 60 - Single Best Answer

A chest X-ray should be performed:

A) anytime pneumonia is being considered.
B) anytime the sputum Gram stain is positive for bacteria.
C) only as a backup if the sputum culture is negative.
D) only in the elderly (>65 years old) and very young (<2 years old).
E) only if bacterial pneumonia is being considered.

Question 61 - Single Best Answer

Destruction of the host respiratory ciliated epithelial layer by Mycoplasma pneumoniae is thought to occur through the production of:

A) peptidoglycan.
B) hydrogen peroxide and superoxide ion.
C) P1 protein.
D) catalase and superoxide dismutase.
E) pneumolysin.

Question 62 - Single Best Answer

A major symptom of patients infected with Corynebacterium diphtheriae is heart damage because:

A) heart cells contain the receptor for heparin-binding epidermal growth factor.
B) heart cells contain the receptor for the bacterial pili.
C) the bacteria invade into heart cells.
D) the bacteria trigger an autoimmune reaction against heart tissue.
E) heart muscle cells uniquely possess elongation factor-2 (EF-2), unlike other host cells.

Question 63 - Single Best Answer

An important virulence factor of Mycobacterium tuberculosis is:

A) a plasmid-encoded exotoxin which causes caseating necrosis.
B) cell wall components that prevent phagosome-lysosome fusion.
C) lipopolysaccharide which induces polyclonal B cell activation.
D) an exotoxin that ADP ribosylates host elongation factor-2 (EF-2).
E) capsular polysaccharide which inhibits phagocytosis.

Question 64 - Single Best Answer

Pseudomonas aeruginosa strains isolated from cystic fibrosis patients are unique compared with other P. aeruginosa strains in that they:

A) are gram-variable.
B) are obligate aerobes.
C) contain no endotoxin in the cell wall.
D) produce mucoid colonies due to alginate overproduction.
E) produce lipoteichoic acid.

Question 65 - Single Best Answer

A 33 year old female in the hospital recovering from a splenectomy presents with sudden onset of chills, cough, and pleuritic pain. She has a fever and produces rust-colored sputum. There is dullness to percussion, bronchial breath sounds, and inspiratory crackles. A culture of blood and sputum would most likely produce an organism that is:

A) gram-negative and citrate-positive.
B) beta-hemolytic and coagulase-positive.
C) beta-hemolytic and sensitive to bacitracin.
D) alpha-hemolytic and sensitive to optochin.
E) acid fast and sensitive to isoniazid.

Question 66 - Single Best Answer

Tracheal cytotoxin (TCT) is unusual in that it is:

A) endotoxin produced by gram-positive bacteria.
B) exotoxin produced by mycoplasmas.
C) a protein with endotoxic activity, similar to superantigens.
D) a component of peptidoglycan.
E) an A-B toxin with 5 B subunits and 1 A subunit.

Question 67 - Single Best Answer

Mycobacterium tuberculosis is not killed by macrophages because:

A) it is insensitive to peroxide.
B) it escapes into the cytoplasm.
C) it has no peptidoglycan in its wall.
D) it inhibits fusion of the phagosome with the lysosome.
E) it secretes a toxin that kills the macrophages.

Question 68 - Single Best Answer

Which of the following patients should be isolated to prevent spread of their disease?

A) Patients with a positive Acid Fast Bacillus sputum smear
B) patients with a positive PPD of >5 mm after 48 hours
C) Cystic fibrosis patients with pseudomonas pneumonia
D) patients in the paroxysmal stage of whooping cough
E) patients in the initial stages of Legionnaire's disease

Question 69 - Single Best Answer

Epiphyses of the long bones are susceptible to seeding by M. tuberculosis because:

A) the concentration of O2 there is low.
B) the concentration of O2 there is high.
C) the concentration of glucose is low.
D) the concentration of glucose is high.
E) the pH is optimal.

Question 70 - Single Best Answer

Each of the following antibiotics is used to treat tuberculosis EXCEPT:

A) isoniazid (INH).
B) amoxicillin.
C) ethambutol.
D) pyrazinimide.
E) rifampin.

Question 71 - Single Best Answer

An outbreak of Staphylococcus aureus infection has occurred in a ChildrenÕs hospital neonatal intensive care unit where five newborns have died of this bacterial infection within a two week period. To trace the source of infection, S. aureus isolates from blood cultures of the infected children, water sources in the hospital, hands of nurses, and door knobs were collected. The bacterial chromosomal DNA was isolated, digested with a restriction enzyme, and subjected to Southern hybridization using the collagen binding adhesin gene as a probe. Which of the following conclusions is MOST LIKELY to be correct?

A) The newborns acquired the infection from a contaminated water source.
B) The newborns acquired the infection from sources other than those tested.
C) The newborns are likely to have acquired the infection from a nurse.
D) The source of infection cannot be determined from the results.
E) The sources of infections differ among the five patients.

Question 72 - Single Best Answer

What do the blue color in the citrate tube and the pink colonies on the MacConkey agar plate have in common?

A) They identify antibiotic-resistant bacteria.
B) They confirm that the bacteria are gram-negative.
C) They confirm the ability of the bacteria to utilize particular carbohydrates.
D) They show that the bacteria are aerobes.
E) None of the above.

Question 73 - Single Best Answer

The organism shown in this Gram stain was placed on a slide containing hydrogen peroxide solution. In the proper context of laboratory diagnosis, the bubbles on the slide indicate that the organism:

A) is a streptococcus.
B) is a staphylococcus.
C) is an anaerobe.
D) is coagulase-positive.
E) is acid-resistant.

Question 74 - Single Best Answer

Which of the following best describe the interpretation of colonies 1 and 2 from this blood agar plate?

A) 1 Ð beta hemolysis, 2 Ð alpha hemolysis
B) 1 Ð beta hemolysis, 2 Ð gamma hemolysis
C) 1 Ð gamma hemolysis, 2 Ð alpha hemolysis
D) 1 Ð alpha hemolysis, 2 Ð gamma hemolysis
E) 1 Ð gamma hemolysis, 2 Ð beta hemolysis

Question 75 - Single Best Answer

This figure shows the results of the Phadebact test. The + and Ð are for the reagent used (- being the negative control, + being the test reagent). What is the significance of the reaction seen in section 3?

A) The patient has a staphylococcal infection.
B) The patient has a Group A streptococcal infection.
C) The test cannot be interpreted because of the blue color in the negative controls (they should have remained clear).
D) The patient made an immune response to Group A streptococci.
E) The bacteria are coagulase-positive.

Question 76 - Single Best Answer

This is a blood agar plate, and the disk contains bacitracin. Assuming that this test was arrived at through an appropriate laboratory diagnostic plan, one can tell that the organism most consistent with this result is:

A) capable of causing rheumatic fever.
B) catalase positive.
C) usually observed as clumps on a Gram stain.
D) Citrate positive
E) Optochin sensitive.