The organisms on the Gram stain at the top of this figure were isolated from the sputum of a patient with a lung abscess. The sputum was yellowish and purulent. The next test in the diagnostic pathway would most likely yield results looking like:
Question 1 - Single Best Answer
A 25 year old female medical student presents with a 38.5C fever, malaise, headache, and cough. She has been ill for 3 weeks. When asked to produce a sputum sample, she cannot. Chest X-ray reveals patchy bronchopneumonia. A cold agglutinin test was positive. Damage to the respiratory tract in this case is most likely being caused by:
A) Tracheal cytotoxin (TCT)
B) Hydrogen peroxide
C) Peptidoglycan
D) Lipopolysaccharide
E) Mycolic acid
Question 2 - Single Best Answer
A 65 year old male who smokes a pack of cigarettes a day and drinks a 6-pack of beer per day experiences fever and chills, a dry, nonproductive cough, and headache getting worse over the course of a week. The man is confused. Chest X-ray reveals multilobar consolidation. Although blood agar cultures of sputum are negative for any pathogens, BCYE agar plates reveal the organism. The relationship between the causative agent and alveolar macrophages is best described as:
A) evasion of phagocytosis by a capsule.
B) evasion of phagocytosis by mycolic acid
C) killing macrophages by a hemolysin
D) inhibition of phagosome-lysosome fusion
E) escaping the phagosome into the cytoplasm
Question 3 - Single Best Answer
Which type of organisms cause the highest number of cases of sepsis in the United States?
A) Gram-positive
B) Gram-negative
C) Fungi
D) Viruses
E) Acid Fast
Question 4 - Single Best Answer
Most of the pathogenic effects of severe sepsis occur at:
A) Alveolar membrane
B) Insterstitial fluid
C) Instestinal lumen
D) Blood vessel endothelium
E) Central nervous system
Question 5 - Single Best Answer
An intensive care unit patient is experiencing a respiratory tract infection. Which of the following is most useful in recognizing preshock so that empiric antibiotics can be initiated to prevent more severe disease?
A) Fever >39C
B) Hypoglycemia
C) Low blood pressure
D) Kidney failure (low urine output)
E) Blood pH >7.45
Question 6 - Single Best Answer
Which of the following are NOT considered part of the standard of care for treating septic shock?
A) intravenous fluid
B) antibiotics
C) corticosteroids
D) All of the above ARE part of the standard of care.
E) None of the above are part of the standard of care because nothing has been shown to be effective in clinical trials.
Question 7 - Single Best Answer
The failure of the numerous non-antibiotic therapies tried so far in treating septic shock and sepsis is most likely related to the fact that:
A) there are numerous effects ongoing at the vascular endothelium.
B) the pathogenesis is based on autoimmune IgG.
C) the pathogenesis is based on autoimmune cell mediated immunity
D) only bacteria cause these syndromes, so antibiotics are sufficient.
E) only immunocompromised patients suffer from these syndromes.
Question 8 - Single Best Answer
Name a component that is UNIQUE to gram-positive bacteria that is used for serological classification: line lipoteichoic acid, teichoic acid
Question 9 - Single Best Answer
Of the antibiotics that are useful against Mycobacteria, which are directed against components that are unique to these bacteria? line ethambutol isoniazid
Question 10 - Single Best Answer
Of the following beta-lactam resistant bacteria, which would most likely be rendered susceptible by the addition of clavulanic acid with a beta-lactam?
A) Methicillin resistant Staphylococcus aureus
B) Mycoplasma pneumoniae
C) Plasmid-containing Haemophilus influenzae
D) Mycobacterium tuberculosis
E) All of the above Clavulanic acid always improves efficacy of beta-lactam antibiotics.
Question 11 - Single Best Answer
A lobar pneumonia patient is treated with a fluoroquinolone. After an initial improvement, the patient relapses with severe disease. A fluoroquinolone-resistant derivative of the initial infecting bacterium is isolated from sputum. The resistant organism does not contain any plasmids. Based on this scenario, the most likely mechanism of antibiotic resistance is:
A) a membrane pump that specifically expels the antibiotic from the bacterial cell.
B) point mutation in the gene encoding gyrase.
C) an enzyme that degrades the antibiotic.
D) the bacterium stopped making gyrase.
E) the gyrase protein is now modified by methylation
Question 12 - Single Best Answer
When bacteria cause disease without spreading through host tissues, what is the most common mechanism of damage?
A) intracellular cytotoxicity.
B) production of a capsule.
C) production of pili.
D) secretion of toxins.
E) None of the above bacteria must always spread through tissues to be successful pathogens.
Question 13 - Single Best Answer
The organisms on the Gram stain at the top of this figure were isolated from the sputum of a patient with a lung abscess. The sputum was yellowish and purulent. The next test in the diagnostic pathway would most likely yield results looking like:
A) Figure A
B) The right side of figure B
C) Parts 1 and 2 of figure C
D) The top tube of Figure D
E) The left tube in Figure E
Question 14 - Single Best Answer
A patient experiences bacteremia with E. coli, a gram-negative rod. His macrophages begin secreting TNF-alpha, IL-1, and IL-6. Which component of the bacterial cell was responsible for this cytokine cascade?
A) O antigen
B) core oligosaccharide
C) Lipid A
D) lipoteichoic acid
E) lipoarabinogalactan
Question 15 - Single Best Answer
All of the following can be associated with BOTH gram-positive and gram-negative bacteria EXCEPT:
A) capsules
B) sensitivity to beta-lactams
C) sensitivity to vancomycin
D) flagella
E) exotoxins
Question 16 - Single Best Answer
Where in a bacterial cell would you expect to find electron transport? line cell membrane, inner membrane, cytoplasmic membrane
Question 17 - Single Best Answer
A 25 year old patient has experienced non-productive cough for two weeks, with malaise, and little to no fever. You suspect Chlamydia pneumoniae. When you send the sputum (what little you could get) off to the lab for culture, you will instruct the lab to plate the sputum on which medium to isolate the Chlamydia?
A) Blood agar
B) Serum tellurite
C) MacConkey
D) Bordet Gengou
E) None of the above
Question 18 - Single Best Answer
The fact that enzymes for transcription in bacteria are different from those of eukaryotes has led to the use of which antibiotic?
A) streptomycin
B) bacitracin
C) oxazolidonones
D) rifampin
E) None of the above
Question 19 - Single Best Answer
Normal flora usually cause: The question should have been preceded with "When they cause disease, " As written it was confusing, so it was thrown out.
A) endogenous infection because of the previously stable relationship with the host.
B) exogenous infection because they usually colonize mucosal surfaces.
C) disease that is not transmissible between humans.
D) disease that does not cause damage to the host.
E) no disease by definition.
Question 20 - Single Best Answer
Which of the following is NOT a known mechanism by which bacteria evade complement?
A) binding host proteins that inactivate complement
B) secreting proteases that degrade complement
C) failing to activate complement
D) inhibit the production of complement components by hepatocytes
E) having thick peptidoglycan
Question 21 - Single Best Answer
Some strains of Group A streptococci secrete superantigen toxins. Which host cells will be DIRECTLY affected by these toxins?
A) PMNs
B) T cells
C) B cells
D) endothelial cells
E) epithelial cells
Question 22 - Single Best Answer
Based on the scheme of pathogenesis and appropriate protective host immune response, which relationship is NOT correct?
A) Legionella pneumophila cell-mediated immunity
B) Streptococcus pneumoniae IgG
C) Mycobacterium tuberculosis sIgA
D) Streptococcus pyogenes IgG
E) Corynebacterium diphtheriae IgG
Question 23 - Single Best Answer
The toxin responsible for most of the damage caused by Corynebacterium diphtheriae has all of the following properties EXCEPT:
A) is encoded by a plasmid
B) is an A-B toxin
C) is the target of vaccination
D) ADP Ribosylates a host protein
E) kills host cells
Question 24 - Single Best Answer
The normal flora of the tracheobronchial tree is:
A) usually gram-positive cocci.
B) usually obligate aerobes.
C) usually gram-negative rods both aerobes and anaerobes.
D) usually wall-less bacteria (Mycoplasmas).
E) None of the above there is no normal flora in the tracheobronchial tree.
Question 25 - Single Best Answer
Egophany is a sign that:
A) there is fluid in the lungs.
B) permanent damage has been caused by infection.
C) the pleural membrane has ruptured.
D) the patient has tuberculosis.
E) the patient's lungs are functioning normally.
Question 26 - Single Best Answer
A single episode or rigor, rust-colored sputum, rales, and shortness of breath are indicative of:
A) viral pneumonia such as influenza,
B) pneumonia caused by the most common bacterial causative agent of community acquired pneumonia.
C) pneumonia caused by a catalase-positive, coagulase-positive, gram-positive coccus that is most known for being found in the nares of even healthy people.
D) a life-threatening infection caused by a pleiomorphic gram-positive rod that secretes a toxin that causes the formation of a pseudomembrane in the respiratory tract.
E) pneumonia caused by a gram-negative rod that infects macrophages by altering phagosomal events.
Question 27 - Single Best Answer
Why are antibiotics an important part of treatment for poststreptococcal glomerulonephritis?
A) The streptococci that initiated the disease by infecting the kidneys must be killed.
B) The secondary infecting bacteria in the kidneys from the urinary tract must be killed.
C) Damage to the kidneys renders the tissues more susceptible to hematogenous infection by normal flora, so prophylaxis is needed.
D) The initial respiratory or skin infection might still be present.
E) None of the above because glomerulonephritis is a nonsuppurative disease like rheumatic fever, antibiotics are not important.
Question 28 - Single Best Answer
MacConkey agar is useful in diagnosing pneumococcal pneumonia because:
A) Streptococcus pneumoniae is lactose-positive.
B) the alpha-hemolysis of the colonies shows up well against the pink/red background of the agar.
C) the bile-sensitivity of the bacteria gives the colonies a distinctive appearance.
D) the optochin reaction in the medium is easy to see.
E) None of the above MacConkey agar is not useful in diagnosis pneumococcal pneumonia.
Question 29 - Single Best Answer
Name one common bacterial agent of respiratory tract infection whose reservoir is the environment instead of humans. line Pseudomonas Legionella
Question 30 - Single Best Answer
Which of the following is NOT a universal trait of pathogenic spore-forming bacteria?
A) gram-positive
B) rod
C) produce dipicolinic acid
D) obligate anaerobe
E) None of the above all spore forming bacteria have all of the above characteristics.
Question 31 - Single Best Answer
What is lysogenic conversion?
A) Changing a gram-positive cell to gram-negative.
B) Changing a rod to a coccus.
C) A plasmid integrating into the chromosome.
D) A bacteriophage encoding a gene that changes the host bacterial cell.
E) A bacteriophage that accidentally picks up a piece of chromosomal DNA during lysis and transfers it to a recipient cell.
Question 32 - Single Best Answer
Antibiotics are societal drugs because:
A) their use impacts the health of people other than those taking them.
B) they are regulated by the federal government.
C) society bears the monetary cost of their purchase.
D) they are advertised in the popular media such as television and magazines.
E) None of the above antibiotics are not societal drugs because they kill bacteria in the people taking them.
Question 33 - Single Best Answer
A patient experiences streptococcal pharyngitis. Each of the following three years the patient experiences streptococcal pharyngitis again. The M protein type of the infecting strains is different each year; however, the M protein type of any of the individual infections did not change over the course of infection. What is the most likely reason for the difference in the M protein types during these infections?
A) an inversion of a segment of DNA in the chromosome.
B) an exchange of DNA sequences from a silent locus in the chromosome to an expressed locus in the chromosome.
C) existence of numerous strains of Group A strep with different M protein types among them.
D) development of resistance to the antibiotic regimen most commonly used to treat streptococcal pharyngitis by the infecting strain.
E) All of the above are equally plausible explanations.
Question 34 - Single Best Answer
Which population of the United States has the highest risk for tuberculosis?
A) sickle cell patients
B) infants
C) immigrants from the developing world
D) i.v. drug abusers
E) alcoholics
Question 35 - Single Best Answer
What primarily determines the location of seeding sites in the body with tuberculosis bacteria during the primary stage?
A) numbers of macrophages
B) oxygen tension
C) amount of lipid
D) competition by normal flora
E) pH
Question 36 - Single Best Answer
Which of the following is most predictive of whether a tuberculosis patient is infectious/contagious or not?
A) positive PPD test
B) positive acid fast sputum stain
C) micronodular (millet seed) interstitial chest X-ray pattern
D) Ghon complex on chest X-ray
E) age >35 years old
Question 37 - Single Best Answer
A 3 year old boy is brought to the hospital with a sore throat, fever, malaise, and difficulty breathing. Physical exam reveals the presence of a gray membrane covering the pharynx. Questioning the mother reveals the boy had not received any vaccinations. If the boys breathing is restored with a tracheostomy but he still gets worse and eventually dies, the cause of his death is MOST LIKELY:
A) rheumatic fever
B) death of heart cells
C) scalded skin syndrome
D) pneumonia
E) necrotizing fasciitis
Question 38 - Single Best Answer
An organism isolated from a very sick newborn is a gram-positive coccus. It is catalas- negative and beta-hemolytic. It is resistant to bacitracin (the A disc). This organism is: line Streptococcus agalactiae or Group B Strep
Question 39 - Single Best Answer
This man's disease disease is encountered via:
A) respiratory droplets
B) mosquito bite
C) soil contaminated with spores
D) corneal transplants
E) ingestion of raspberries contaminated with soil
Question 40 - Single Best Answer
The catarrhal stage of whooping cough is most like the infection caused by which of the following?
A) rhinovirus
B) CMV
C) HSV 1
D) Neisseria gonorrhoea
E) Clostridium perfringens
Question 41 - Single Best Answer
Members of the genus Clostridium often produce butyric acid which can make infections smell like rancid butter. This molecule is produced:
A) to stabilize the spore coat
B) to kill cells and allow the organism spread
C) as part of the LPS
D) by oxidation as an end product of respiration
E) by reduction so NADH can be oxidized
Question 42 - Single Best Answer
An energized membrane is produced:
A) when sodium is pumped into the cell
B) when H+ is pumped into the cell
C) when H+ is pumped out of the cell
D) when ATP is pumped out of the cell
E) when pyruvate is converted to lactic acid
Question 43 - Single Best Answer
When a bacterium is grown in the presence of glucose and lactose it will utilize the glucose first. It does this by:
A) turning off the lactose transport system
B) inhibiting production of ATP
C) inhibiting production of an energized membrane
D) inhibiting fermentation
E) inhibiting respiration
Question 44 - Single Best Answer
The genes for enzymes that destroy antibiotics are usually encoded on line plasmids or transposons
Question 45 - Single Best Answer
Giving antibiotics inappropriately (i.e., when they can do no good) will:
A) cause mutations to antibiotic resistance
B) select organisms that have pre-existing antibiotic resistance genes
C) increase the rate of transfer of antibiotic-resistant plasmids
D) stimulate sporulation of bacteria in the GI tract and cause disease
E) kill antibiotic resistant normal flora
Question 46 - Single Best Answer
Finding a catalase-negative, alpha-hemolytic, gram-positive coccus that is optochin-resistant in a sputum sample that contains many epithelial cells of an individual with a severe cough most likely means:
A) the person is in the paroxysmal stage of whooping cough
B) the person has chronic bronchitis
C) the person has pneumonia caused by Streptococcus pneumoniae
D) the person has influenza
E) nothing - This is most likely normal mouth flora
Question 47 - Single Best Answer
Streptococcus pneumoniae can have resistance to penicillin that is unusual in that:
A) it is caused by a heat stable beta lactamase
B) its genetic determinants are on a phage
C) its genetic determinants are on a plasmid
D) its genetic determinants are point mutations on the bacterial chromosome
E) only non-encapsulated organisms are resistant
Question 48 - Single Best Answer
The most common cause of pharyngitis is line viruses
Question 49 - Single Best Answer
Three bacterial causes of pharyngitis are line Neisseria gonorrhoea, Streptococcus pyogenes, Corynebacterium diphtheriae
Question 50 - Single Best Answer
To diagnose acute epiglottitis one:
A) does a blood culture.
B) collects sputum, checks for epithelial cells, then does a sputum culture.
C) swabs the epiglottis and plates on EMB agar.
D) does a bladder aspiration and checks for antigen from the pathogen.
E) looks for IgG with an ELISA test.
Question 51 - Single Best Answer
To identify an organism with PCR one must have previously:
A) partially sequenced the organism to identify unique sequences
B) done a RFLP analysis on the organism
C) done an ELISA test with monoclonal antibody
D) grown the organism on blood agar
E) grown the organism on EMB agar
Question 52 - Single Best Answer
Which of the following is NOT part of the mechanism of action of diphtheria toxin?
A) NAD is hydrolyzed.
B) A protein is ADP-ribosylated.
C) EF2 is inactivated.
D) The level of cAMP rises.
E) The toxin is cleaved and the A portion enters the cytoplasm.
Question 53 - Single Best Answer
A young adult has a sore throat and difficulty swallowing. She had been feeling tired and "achy" for about 10 days. Her temperature was 100F and her throat was red with an exudate. Her tonsils were swollen and touched at mid-line. A throat swab did not produce any beta-hemolytic colonies on a blood agar plate. She is heterophile antibody +.
The causative agent of her sore throat most likely is:
A) Streptococcus pyogenes
B) Streptococcus pneumoniae
C) Bordetella pertussis
D) Herpes simplex virus
E) Epstein Barr virus
Question 54 - Single Best Answer
The components of the currently used whooping cough vaccine are: line FHA and pertussis toxoid
Question 55 - Single Best Answer
A disease of children characterized by a barking cough and stridor is caused by?
A) Bordetella pertussis
B) Corynebacterium diphtheriae
C) Respiratory Syncitial Virus
D) Influenza virus
E) Hemophilus influenzae
Question 56 - Single Best Answer
An epidemic of Staphylococcal infections has appeared in the NICU. In an attempt to curtail the number of infections you wish to determine who is the carrier of the particular strain found in the NICU. You would therefore sample which of the following sites in the hospital personnel?
A) pharynx
B) skin
C) blood
D) nose
E) feces
Question 57 - Single Best Answer
The shortness of breath in pneumococcal pneumonia is due to
A) a toxin that constricts the bronchioles.
B) bacteria killing the lung cells.
C) killer T-cells that kill the lung tissue.
D) infiltration of fluid into the alveoli.
E) death of muscle cells by an ADP-Ribosylating toxin encoded on a phage.
Question 58 - Single Best Answer
Individuals who do NOT smoke or drink will likely suffer from what disease when exposed to Legionella pneumophila?
A) a likely fatal pneumonia
B) amebiasis
C) Pontiac fever
D) heart and nerve damage
E) myringitis and severe ear pain
Question 59 - Single Best Answer
A child with cystic fibrosis is found to be colonized with a bacterium that forms large colonies, produces bluish-green pigmentation, and gives off a fruity odor. Besides cystic fibrosis patients, this bacterium is most likely to be found infecting:
A) burns
B) anaerobic wounds
C) the meninges
D) sickle cell anemics
E) pharynx
Question 60 - Single Best Answer
Why is it important NOT to treat a patient with active TB with isoniazid prohylaxis?
A) It will kill off normal flora and enable the mycobacteria to grow out.
B) Actively growing mycobacteria are not sensitive to isoniazid.
C) During active TB the bacteria are not replicating, and only replicating bacteria are sensitive to isoniazid.
D) The mycobacterial burden is very high, so there is a good chance that there are existing isonoazid-resistant mutants in the patient.
E) None of the above Treating patients with active TB with isoniazid alone is the standard of care.
Question 61 - Single Best Answer
Influenza virus infection may cause three different syndromes of varying severity. The severity of these three syndromes is indicated in the graph above. In which of these syndromes would you be likely to find rusty-colored sputum?
A) the red line (that goes straight up)
B) the black line (that goes up and then comes down)
C) the green line (that starts to go down and then goes up)
D) none of the above
Question 62 - Single Best Answer
Which of the following does NOT require special media for culture (other than blood agar)?
A) Bordetella pertussis
B) Corynebacterium diphtheria
C) Streptococcus pneumoniae
D) Mycoplasma pneumoniae
E) Legionella pneumophila
Question 63 - Single Best Answer
Which of the following most accurately describes the hemolysis of colonies 1 and 2 in the figure of a blood agar plate?
A) 1 alpha, 2 beta
B) 1 gamma, 2 alpha
C) 1 gamma, 2 beta
D) 1 beta, 2 gamma
E) 1 alpha, 2 gamma
Question 64 - Single Best Answer
LS is a 55 year old BM with a past history of TB contact 30 years ago and 85% body burns sustained in a house fire 9 years ago. He presents to the Shands ER with a A chief complaint (CC) of 1 wk history of right pleuritic chest pain He had been feeling well until 1 week ago when he noted the onset of right sided chest pains. Pain was sharp and made much worse by deep inspiration and was located in midlateral part of his right chest. He first noticed the pain several days after lifting heavy objects. He denied fever, chills, night sweats, or anorexia, but noted a recent cough productive of yellow sputum (approximately 6 days). He was unsure if he had lost any weight. On further questioning he reported that he consumed a six-pack of beer daily. He also reported a recent bout of heavy drinking with friends. He denies any loss of consciousness.
Past Medical History: He received one year of INH prophylaxis 20 years ago.
Social History: smoke 1 ppd x 25 years, unemployed, lives alone
PE: Temp 38.4C, BP 120/80, P 90, RR 34 (shallow),
HEENT: Poor dentition with gingivitis
Fundi: no hemorrhages or exudates
Neck: supple, no palpable nodes
Heart: Normal S1 and S2 no murmurs
Lungs: Bronchial breath sounds and egophony in the right upper lung field.
Abdomen: no organomegally, and no tenderness
Extremities: clubbing, but no cyanosis
Lab WBC 9,900 70% mature PMN 7% band forms Hct 35
CXR: RUL mass
CT scan of the chest: A discrete cavity 2 x 2 cm with an air fluid level in the posterior lateral region of the right upper lobe.
1. What is the most likely diagnosis?
2. Explain the basis for your diagnosis. Please refer to specific details of the clinical presentation (provide at least 3 findings that support your diagnosis)
3. We have reviewed many of the risk factors associated with pulmonary infections What risk factors apply to this patient? (List at least 3)
4. What three tests would be most helpful for confirming your presumed diagnosis?
Be sure to include the numbers in your answer to help grading. text