Images A and B are Gram stains. Image 1 is a blood agar plate with an optochin disk. Image 2 is a blood agar plate with a bacitracin disk. Which images of strains (A or B) match images of the most consistent blood agar plate result (1 or 2)?
Question 1 - Single Best Answer
Each of the following accurately describes aspects of diagnosing or managing pneumonia EXCEPT:
A) Antibiotics should be initiated within 4 to 8 hours.
B) Sputum culture should not be ordered without a sputum Gram stain.
C) Blood cultures should be drawn for all hospitalized patients.
D) Chest X-ray should be done whenever pneumonia is considered.
E) Pulmonary auscultation over-estimates extent of pneumonia.
Question 2 - Single Best Answer
Images A and B are Gram stains. Image 1 is a blood agar plate with an optochin disk. Image 2 is a blood agar plate with a bacitracin disk. Which images of strains (A or B) match images of the most consistent blood agar plate result (1 or 2)?
A) A-1; B-2
B) A-2; B-1
C) A-1; B-1
D) A-2; B-2
Question 3 - Single Best Answer
Write the letters of the following steps in severe sepsis/shock in the order in which they occur during a typical disease progression. A-cytokine production; B-infection; C-NFKB activation; D-Toll-Like Receptor stimulation; E-vascular effects/symptoms line B D C A E
Question 4 - Single Best Answer
What do diphtheria and Strep throat have in common?
A) They both frequently cause blockage of the trachea and trouble breathing.
B) Damage is caused by the host adaptive immune response.
C) They can both cause heart problems.
D) Neither organism spreads through tissues.
E) There is an effective vaccine to prevent both diseases.
Question 5 - Single Best Answer
At which stage of whooping cough are the number of bacteria the highest in the respiratory tract?
A) Incubation period.
B) Paroxysmal
C) Catarrhal
D) Convalescent
E) Latent
Question 6 - Single Best Answer
Which of the following relationships about antibiotics is correct?
A) Low therapeutic index is good, low minimum inhibitory concentration is good.
B) High therapeutic index is good, low minimum inhibitory concentration is good.
C) High therapeutic index is good, high minimum inhibitory concentration is good.
D) Low therapeutic index is good, high minimum inhibitory concentration is good.
E) None of the above. These values do not predict usefulness of antibiotics.
Question 7 - Single Best Answer
What are the four antibiotics primarily used to treat tuberculosis? line ethambutol, isoniazid, rifampicin, pyrazinamideŠ.dapsone is not used for tb
Question 8 - Single Best Answer
The importance of the third amino acid in the peptidoglycan chain having an amino-containing group is:
A) this is the site of vancomycin activity.
B) it is involved in polymerization of the backbone.
C) that the O-antigen is attached at that site.
D) it is involved with cross-linking.
E) None of the above are true.
Question 9 - Single Best Answer
A person aspirates 1000 cells of Streptococcus pneumoniae into their alveoli. The bacteria double every hour. Assuming that there is no death of the bacteria, how long will it take for the number of bacteria to reach 1 million cells?
A) 6 to 7 hours
B) 9 to 10 hours
C) 12 to 15 hours
D) about 1 day
E) about 1 week
Question 10 - Single Best Answer
Type 3 secreted proteins would most likely be involved with which of the following pathogenic mechanisms?
A) degrading sIgA
B) inducing apoptosis of host cells
C) cleaving receptors off the surface of host cells
D) inducing genetic exchange
E) binding host proteins to the surface of bacteria for antigenic cloaking
Question 11 - Single Best Answer
Tracheal cytotoxin (TCT) is a unique exotoxin because:
A) it is secreted by gram-negative bacteria.
B) it halts transcription of host cells.
C) it is composed of lipopolysaccharide.
D) it is not composed of protein.
E) None of the above. TCT is a typical exotoxin.
Question 12 - Single Best Answer
How does M protein help Streptococcus pyogenes evade phagocytes?
A) It binds factor H which inhibits complement.
B) It kills macrophages and neutrophils.
C) It is a C5a peptidase.
D) It prevents phagosome-lysosome fusion.
E) It quenches oxidative burst.
Question 13 - Single Best Answer
What do antibiotic resistance mechanisms for Methicillin Resistant Staphylococcus aureus and the increasing penicillin resistance in Streptococcus pneumoniae have in common?
A) Plasmids encoding transposons with beta-lactamase.
B) Altered target in the form of D-Ala-D-lactate
C) Penicillin binding proteins that are resistant to beta-lactams.
D) membrane pumps to keep intracellular levels of beta-lactams low.
E) None of the above. MRSA and penicillin-resistant S. pneumoniae have nothing in common.
Question 14 - Single Best Answer
The most important function of transposons in infectious diseases is:
A) moving plasmids between bacterial cells of different species.
B) making bacterial cells competent for transformation.
C) moving antibiotic resistance genes among genetic elements.
D) making plasmids able to be conjugated between cells.
E) All of the above are important functions of transposons.
Question 15 - Single Best Answer
A 73-year-old man was admitted to the hospital because of breathing difficulties, chest pain, chills, and fever of several days' duration. He had been well until 1 week before admission, when he noted the onset of a persistent headache and a productive cough. The patient smoked two packs of cigarettes a day for more than 50 years and drank a six-pack of beer daily; he also had a history of bronchitis. Physical examination revealed an elderly man in severe respiratory distress with a temperature of 39°C, pulse of 120 beats/minutes, respiratory rate of 36 breaths/minutes, and blood pressure of 145/95 mm Hg. Hematocrit was normal. Chest radiograph revealed an infiltrate in the middle and lower lobes of the right lung. The white blood cell count was 14,000 cells/mm3 (80% polymorphonuclear neutrophils). Gram stain of the sputum showed neutrophils but no bacteria, and routine bacterial cultures of sputum and blood were negative for organisms. The absence of observable bacteria in the sputum and cultures are most likely due to:
A) the patient has a viral infection.
B) the patient has an allergic reaction, such as to an antibiotic, causing his symptoms.
C) the organism requires special staining and culture techniques.
D) the patient is suffering from inhalation of nitrogen oxides.
E) the patient has lung cancer.
Question 16 - Single Best Answer
Bacterial cells lack all of the following EXCEPT:
A) Electron transport
B) Microtubules
C) Nuclear membranes.
D) Mitochondria.
E) Bacteria lack all of the above.
Question 17 - Single Best Answer
A barking cough and stridor in a child are most likely signs of:
A) asthma.
B) RSV infection.
C) whooping cough.
D) diphtheria.
E) influenza pneumonia.
Question 18 - Single Best Answer
All of the following about the normal flora are true EXCEPT:
A) The normal flora can cause disease.
B) The normal flora can protect against disease by stimulating cross-protective immunity.
C) The normal flora can protect against disease by occupying sites to prevent colonization by pathogens.
D) The normal flora can produce essential nutrients.
E) All of the above are true.
Question 19 - Single Best Answer
Which of the following is NOT a known mechanism of evasion of antibodies produced by the host?
A) Binding host proteins to the bacterial cell surface.
B) Bacteria producing surface antigens which mimic the host.
C) Genetic rearrangement resulting in changes in the major surface antigens.
D) Secreting proteases that degrade certain classes of antibodies.
E) ALL of the above ARE known mechanisms of evasion of host defenses.
Question 20 - Single Best Answer
Organisms that can cause diseases called "walking" pneumonia include:
A) Mycobacterium and Mycoplasma.
B) Mycobacterium and Streptococcus
C) Mycoplasma and Chlamydia.
D) Streptococcus and Klebsiella
E) Chlamydia and Klebsiella
Question 21 - Single Best Answer
Pseudomonas aeruginosa strains isolated from cystic fibrosis patients are unique from strains causing other infections in that they:
A) are obligate anaerobes.
B) contain no endotoxin in the cell wall.
C) produce mucoid colonies due to alginate overproduction
D) have no peptidoglycan.
E) None of the above. There is nothing unique about Pseudomonas strains isolated from CF patients.
Question 22 - Single Best Answer
Based on the pathogenic process for tuberculosis, the most effective vaccine would elicit which type/form of adaptive immunity? line cell-mediated immunity
Question 23 - Single Best Answer
The major difference between vancomycin and beta-lactam antibiotics is:
A) Vancomycin binds the substrate for transpeptidation, while beta-lactams bind the enzyme.
B) There is no resistance to vancomycin, while resistance to beta-lactams is rampant.
C) Vancomycin inhibits ribosomes, while beta-lactams inhibit peptidoglycan.
D) Vancomycin is only effective against gram-positive organisms, while beta-lactams are effective only against gram-negative organisms.
E) None of the above.
Question 24 - Single Best Answer
What is the single most defining symptom differentiating severe sepsis from septic shock? line hypoperfusion despite fluid administration
Question 25 - Single Best Answer
This image is of a blood agar plate with two different kinds of bacteria. Which of the following correctly describes the hemolysis of these colonies?
A) 1-alpha, 2-beta
B) 1-beta, 2-gamma
C) 1-gamma, 2-beta
D) 1-gamma, 2-alpha
E) 1-alpha, 2-gamma
Question 26 - Single Best Answer
Each of the following bacterial species has strains that are resistant to all useful antibiotics EXCEPT:
A) Pseudomonas aeruginosa.
B) Streptococcus pyogenes.
C) Enterococcus faecalis.
D) Mycobacterium tuberculosis.
E) All of the above have essentially untreatable strains.
Question 27 - Single Best Answer
A homeless 70 year-old man has a 104F fever and respiratory distress. Chest X-ray reveals lower lobe cavitation. Gram-negative rods which were lactose-positive, citrate-positive were cultured from his sputum. His sputum most likely looked like:
A) Current jelly.
B) Thin and watery.
C) Yellow-green.
D) Rust-colored
E) Bloody (hemoptysis).
Question 28 - Single Best Answer
A 10 year old male of an immigrant family from a developing country who has not received childhood vaccinations presents with enlarged cervical lymph nodes, fever, sore throat, and tough, yellow material in the anterior pharynx. Treatment for the most likely disease of this child is: line antibiotics and antitoxin
Question 29 - Single Best Answer
All of the following are part of Jones criteria for post-streptococcal rheumatic fever EXCEPT:
A) polyarthritis
B) chorea
C) diffuse red rash that spares the palms and soles
D) a red rash with well defined borders
E) subcutaneous nodules
Question 30 - Single Best Answer
In terms of toxicity, which single class of antibiotics is the safest and which single class of antibiotics is the most toxic? Note, list the class, not the target. line safest cephalosporins, toxic aminoglycosides
Question 31 - Single Best Answer
Clavulanic acid:
A) inhibits beta-lactamase.
B) inhibits lipopolysaccharide synthesis.
C) is the equivalent of teichoic acid but in gram-negative bacteria.
D) is a component of the cell wall of gram-positive bacteria
E) is active only against acid-fast bacteria.
Question 32 - Single Best Answer
A 5-year-old girl was brought to the local public health clinic because of a severe, intractable cough. During the previous 10 days, she had a persistent cold that had worsened. The cough developed the previous day and was so severe that vomiting frequently followed it. The child appeared exhausted from the coughing episodes. A blood cell count showed a marked leukocytosis with a predominance of lymphocytes. What special medium would you suggest the microbiology lab use to culture the important pathogen in this case?
A) Blood agar
B) Bordet-Gengou agar
C) MacConkey agar
D) Serum tellurite
E) None of the above. This is most likely a viral infection for which culture is not practical.
Question 33 - Single Best Answer
In terms of the bacterial-host interaction with phagocytes, which of the following pairs of microorganisms is most similar?
A) Streptococcus pneumoniae and Legionella pneumophila
B) Streptococcus pneumoniae and Mycobacterium tuberculosis
C) Legionella pneumophila and Mycobacterium tuberculosis
D) Corynebacterium diphtheriae and Mycobacterium tuberculosis
E) Bordetella pertussis and Streptococcus pneumoniae
Question 34 - Single Best Answer
Fetid breath and an abnormal chest X-ray in a patient subject to loss of consciousness point to:
A) Pneumococcal pneumonia.
B) Reactivated tuberculosis.
C) Pneumonia caused by anaerobic bacteria
D) Chronic bronchitis.
E) Influenza virus infection.
Question 35 - Single Best Answer
Mechanisms by which bacteria can become resistant to antibiotics include all of the following EXCEPT:
A) an alteration in the target of the antibiotic.
B) the production of an enzyme that breaks down the antibiotic.
C) a mechanism to pump the antibiotic out of the bacterial cell.
D) production of an alternative metabolic pathway.
E) inhibiting synthesis of the antibiotic.
Question 36 - Single Best Answer
The Phadebact test for Streptococcus pyogenes is an assay for presence of what in a patient's sample?
A) M protein
B) hyaluronic acid capsule
C) lipoteichoic acid
D) Group A carbohydrate
E) Protein A.
Question 37 - Single Best Answer
The difference between anaerobic respiration and fermentation as a means of biological oxidation is:
A) fermentation requires oxygen, anaerobic respiration does not
B) fermentation utilizes inorganic molecules as terminal electron acceptors, anaerobic respiration utilizes organic molecules as terminal electron acceptors
C) anaerobic respiration results in regeneration of NAD while fermentation does not
D) only obligate anaerobes can carry out anaerobic respiration
E) anaerobic respiration directly results in an energized membrane, while fermentation does not.
Question 38 - Single Best Answer
Transposase mediates:
A) conjugation of plasmids.
B) movement of insertion sequences
C) specialized transduction.
D) cross linking of the peptidoglycan.
E) transformation.
Question 39 - Single Best Answer
All of the following are essential steps in pathogenesis of infection for all pathogens EXCEPT:
A) Multiplication within the host.
B) Causing damage to cells or tissues.
C) Evading relevant host defenses.
D) Spreading through tissues.
E) None of the above. There are no optional steps in pathogenesis.
Question 40 - Single Best Answer
The PPD test:
A) is based on measuring induration.
B) is based on measuring erythema.
C) is based on measuring the fluid-filled vesicles.
D) is not valid in a person previously vaccinated with BCG.
E) always means active disease.
Question 41 - Single Best Answer
What is the distinguishing characteristic of group translocation in bacteria?
A) Groups of bacteria invade through the epithelium, as opposed to individual cells.
B) Type 3 secreted proteins enter the cytoplasm of host cells.
C) A sugar is phosphorylated as it is taken up into the bacterial cell.
D) A transposon moves several different antibiotic resistances at once.
E) Phages can only transduce genes next to their integration site in the chromosome.
Question 42 - Single Best Answer
The tubes in this picture contain rabbit plasma mixed with bacteria. Assuming that you performed the test correctly and it is relevant to your diagnosis, the result in tube B means:
A) the organism is incapable of causing disease in humans.
B) the organism was a viridans streptococcus instead of Streptococcus pneumoniae.
C) the organism was not Staphylococcus aureus.
D) the patient did not produce autoreactive antibodies.
E) None of the above.
Question 43 - Single Best Answer
Why are anti-streptolysin O (ASO) antibodies measured in patients suspected of having post-streptococcal rheumatic fever?
A) These cross-reactive antibodies are causing damage to the heart tissue.
B) It is impossible to sample the heart tissue to detect the bacterial infection of those tissues.
C) The bacterial infection that initiated the disease process may be absent upon presentation of symptoms for rheumatic fever.
D) ASO antibodies are used in the Phadebact test to positively identify Group A streptococci from other beta-hemolytic streptococci.
E) None of the above. ASO titers are only used for post-streptococcal glomerulonephritis.
Question 44 - Single Best Answer
If you were told that a bacterial pathogen had a capsular antigen, you would most likely assume that:
A) it was an extracellular pathogen.
B) it was gram-positive.
C) it was sensitive to vancomycin.
D) it was an opportunistic pathogen.
E) all of the above
Question 45 - Single Best Answer
Headache, cough, a low-grade fever, and chills developed in a 21-year-old university student. When she was seen at the student health center, she had a nonproductive cough and shortness of breath on exertion. Her pulse rate was 95 beats/min, and her respiratory rate was 28 breaths/min. Her pharynx was erythematous; scattered rhonchi and rales but no consolidation were noted on auscultation. Results of a chest radiograph showed patchy infiltrates. A Gram stain of sputum revealed many white blood cells but no organisms. Her serum was positive for cold agglutinins. The surface components of the most likely causative agent include:
A) waxes and lipids
B) sterols
C) thick peptidoglycan
D) an outer membrane
E) dipicolinic acid.
Question 46 - Single Best Answer
A previously erythromycin susceptible strain becomes erythromycin resistant. Erythromycin inhibits protein synthesis by binding to a ribosomal RNA. In one form of erythromycin resistance the rRNA is methylated. The most likely genetic basis for such methylation of rRNA is:
A) point mutation in the rRNA gene.
B) plasmid-encoded methylase gene.
C) innate resistance
D) point mutation in a membrane pump.
E) None of the above are consistent with this form of resistance.
Question 47 - Single Best Answer
If you plate an equal mixture of Streptococcus pyogenes and Klebsiella on a blood agar plate and a MacConkey agar plate, which of the following best describes the result?
A) More colonies on the MacConkey agar because it contains lactose that both bacteria can utilize.
B) More colonies on the blood agar because it is a rich medium with no inhibitory ingredients.
C) Equal numbers of colonies on both plates because they are both differential.
D) Equal numbers of colonies on both plates because they are both selective.
E) Only streptococci growing on the blood agar plate and only Klebsiella growing on the MacConkey agar plate.
Question 48 - Single Best Answer
A 13 year old boy presents with a sudden onset of headache, fever, erythematous tonsils with visible exudate, and swollen cervical lymph nodes. A throat swab is used with a Phadebact Group A test in your office, with the results for this patient shown in panels 1 and 2 of the figure. The + and - refer to the reagent used in the panel. The most correct course of action is to:
A) provide symptomatic treatment, since the patient has a viral infection.
B) initiate antibiotic and anti-toxin therapy.
C) culture the throat on blood agar and await the results for possible antibiotics.
D) culture the throat on Bordet-Gengou agar and initiate antibiotic treatment.
E) culture the throat on BCYE agar and initiate antibiotic treatment .
Question 49 - Single Best Answer
Filamentous Hemagglutinin (FHA) of Bordetella pertussis is:
A) an adherence factor present in the current vaccine.
B) an antiphagocytic factor.
C) a toxin that causes neurological damage
D) composed of the peptidoglycan building block
E) a specific target of antibiotic treatment for whooping cough.
Question 50 - Single Best Answer
Each of the following is a symptom of Systemic Inflammatory Response Syndrome EXCEPT:
A) temperature <36C
B) heart rate >90 bpm
C) weight loss of >5% over 2 week period
D) respiratory rate >20 bpm
E) white blood cell count <4,000
Question 51 - Single Best Answer
Having obtained appropriate cultures and initiated empiric therapy, the 3 day rule of Dr. Southwick indicates each of the following EXCEPT:
A) re-examine the patient if culture is negative
B) re-examine the patient if culture indicates colonization without disease
C) use the antibiotics with the narrowest spectrum that is effective
D) use the fewest number of antibiotics that are effective
E) discontinue the antibiotics at 3 days if the symptoms have cleared.
Question 52 - Single Best Answer
In terms of biological activity lipid A is most closely related to
A) sterols
B) pentaglycine bridge
C) superantigens
D) capsule
E) porins
Question 53 - Single Best Answer
To control the number of MRSA, the most productive course of action would be to
A) stop using methicillin to treat MRSA
B) stop using methicillin to treat anything
C) always use clavulanic acid with methicillin
D) always use bacteriophage in conjunction with methicillin to treat MRSA
E) eliminate the use of methicillin in cattle feed
Question 54 - Single Best Answer
Finding an alpha-hemolytic, optochin-sensitive bacterium in a throat swab of a patient with a fever and cough definitely means:
A) the patient is at risk for rheumatic fever.
B) the patient will develop a severe cough in a week-10 days.
C) the patient has otitis media.
D) the patients fever will go away by itself.
E) None of the above.
Question 55 - Single Best Answer
Erythromycin can be used to treat Mycoplasma infections because:
A) Mycoplasma has ribosomes.
B) Mycoplasma does not have a cell wall.
C) Mycoplasma cannot utilize folic acid from the environment.
D) Mycoplasma is an obligate anaerobe.
E) Mycoplasma has rough lipopolysaccharide.
Question 56 - Single Best Answer
The source of the ADP-ribose group that is added to EF2 by diphtheria toxin is
A) NAD
B) cyclic AMP
C) ATP
D) RNA
E) the bacterial cytoplasm
Question 57 - Single Best Answer
Influenza virus predisposes to bacterial pneumonia by Line denuding the ciliated epithelium
Question 58 - Single Best Answer
Protein A of Staphylococcus aureus:
A) makes the bacterium beta hemolytic.
B) attaches the bacterium to epithelial cells.
C) binds antibodies to activate complement.
D) attaches host proteins to the bacteria to make it immunologically invisible.
E) degrades IgA.
Question 59 - Single Best Answer
Name 4 microbes that are potentially carcinogenic Line Helicobacter, EBV, papilloma, Hepatitis B, Hepatitis C, HTLVŠ HIV is not carcinogenic!
Question 60 - Single Best Answer
Which of the following sets of antibiotics has related targets?
A) bacitracin, tetracycline, quinolones
B) cephalosporins, macrolides, trimethoprim
C) aminoglycosides, streptogramins, macrolides
D) vancomycin, bacitracin, oxazolidinones
E) sulfonamides, metronidazole, monobactams
Question 61 - Single Best Answer
Which population/group has the highest incidence of community acquired pneumonia? line elderly or >65 yo
Question 62 - Single Best Answer
A fast and sensitive test for Legionella is:
A) grow on blood agar and look for gamma hemolytic colonies
B) look for Legionella antigen in urine
C) look for IgG antibodies to Legionella
D) do a PPD test
E) do a mouse inoculation test
Question 63 - Single Best Answer
Your patient in an intensive care unit presents with fever, symptoms of hypoperfusion, hypotension, and increased WBC. Blood cultures are drawn. You then initiate empiric broad spectrum antibiotics. The next day the blood cultures are negative, and the patient is still ill. The most correct course of action at this point is to:
A) Stop the antibiotics since there is no infection going on. The patient most likely has pancreatitis.
B) Continue the antibiotic treatment.
C) Change to a more narrow spectrum antibiotic.
D) Order a full body MRI to find the focus of infection.
E) None of the above are appropriate.
Question 64 - Single Best Answer
Each of the following contribute to a positive diagnosis of miliary tuberculosis EXCEPT:
A) positive blood cultures.
B) leukemoid reaction.
C) cavitary lesions on chest X-ray
D) night sweats
E) choroid tubercles on funduscopic examination
Question 65 - Single Best Answer
Mr. G is a 26 yo white male with no significant past medical problems. 1 week prior to admission he developed rhinitis, sinus headache and a nonproductive night time cough. He continued his daily activities 2-3 days prior to hospital admission he noted the onset of severe myalgias associated with fever and shortness of breath. Because of his worsening shortness of breath he went to the emergency room.<br><br>PE: Temp to 39°C; Respiratory Rate: 22; Blood Pressure: 151/75; Pulse: 110<br>Throat mild erythema<br>Teeth in good repair<br>Heart Nl S1 and S2 no murmurs<br>Lungs: e to a changes and loud rhonchi left posterior lung field.<br>Abdomen soft and nontender<br>Extremities: no edema<br>Skin: no rashes<br>LAB: Peripheral WBC 40,000 (89% PMN)<br>Sputum Gram stain and culture performed.<br>CXR showed a Left Lower Lobe infiltrate and a left pleural effusion.<br><br>Please describe how Mr. G most likely developed pneumonia. Speculate on the most likely cause of his pneumonia. Be specific as to the reasons you have chosen this diagnosis. (Mention at least 3 reasons). What two additional tests would be very helpful in assessing the cause of his pneumonia. Text Answers Risk factors (1 point): The only risk factor her was a viral URI. (1 point for the correct answer)<br><br>Etiology (3 points): Acute onset of symptoms including fever and shortness of breath are suggestive of typical pneumonia (1 point) <br><br>Physical findings of e to a changes and rhonchi is more consistent with a typical pneumonia (1 point). CXR: Left lower lobe infiltrate and pleural effusion also suggests a typical pneumonia (1 point) Myalgias are nonspecific and are not helpful in this case. Actual etiology was S. pneumoniae. Other forms of typical bacterial pneumonia are unlikely in this young man.<br><br>Other tests (1 point):<br>Blood cultures (positive for S. pneumoniae)<br>Pleural fluid tap: yielded 1020 WBC (89% PMN) Glucose 10, LDH 600, pH 7.1. A chest tube was placed based on these findings. (0.5 points for each test)