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clinical bateriology Flashcards

1
Q

Name the four illnesses most commonly caused by Streptococcus pneumoniae infection.

A

Meningitis, otitis media (in kids), pneumonia, & sinusitis—mops are most optochin sensitive

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2
Q

Name five gram-positive rods. Which one of the five is anaerobic?

A

Clostridium, Listeria, Bacillus, Mycobacterium, and Corynebacterium; Clostridium is anaerobic

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3
Q

Why is silver stain normally used to view Legionella pneumophila?

A

Because it Gram stains poorly

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4
Q

Staphylococcus saprophyticus is novobiocin ____ (resistant/sensitive); S. epidermidis is novobiocin ____ (resistant/sensitive).

A

Resistant; sensitive (on the office staph retreat, there was no stres)s

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5
Q

The two main α-hemolytic bacteria are catalase ____ (positive/negative). ____ is/are optochin sensitive; ____ is/are optochin resistant.

A

Negative; Streptococcus pneumoniae; viridans streptococci

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6
Q

Name four β-hemolytic bacteria and describe how they appear on blood agar.

A

Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Listeria monocytogenes; they form clear areas of hemolysis on agar

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7
Q

Name four diseases that can be caused by Haemophilus influenzae.

A

Epiglottitis, Meningitis, Otitis media, and Pneumonia (these are caused by HaEMOPhilus)

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8
Q

What is the mechanism of action of Staphylococcus aureus protein A?

A

It binds the Fc region of immunoglobulin G (Fc-IgG), inhibiting complement fixation and phagocytosis

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9
Q

Which species of Neisseria has a polysaccharide capsule: meningitidis or gonorrhoeae?

A

N. meningitidis only

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10
Q

Gram-negative bacilli are resistant to penicillin G but may be susceptible to which penicillin derivatives?

A

Ampicillin and amoxicillin

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11
Q

What type of bacteria grow pink colonies on MacConkey agar?

A

Lactose-fermenting enteric bacteria: Citrobacter, Klebsiella, E. coli, Enterobacter, Serratia

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12
Q

What bacterium found in normal skin flora commonly contaminates blood cultures and infects prosthetics and catheters?

A

Staphylococcus epidermidis

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13
Q

A woman develops a non-E. coli urinary tract infection. What is the next most likely organism?

A

Staphylococcus saprophyticus (second most common cause of uncomplicated UTI in young women, after E. coli)

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14
Q

What is the treatment of choice for Pseudomonas aeruginosa infection?

A

Aminoglycoside plus an extended-spectrum penicillin (e.g., piperacillin, ticarcillin, cefepime, imipenem, meropenem)

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15
Q

In the viridans group streptococci, Streptococcus ____ causes subacute bacterial endocarditis; Streptococcus ____ causes dental caries.

A

sanguinis (S. sanguinis = blood; there is a lot of blood in the heart, and the bacterium sticks to damaged valves); mutans

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16
Q

What three pyogenic infections does Streptococcus pyogenes cause?

A

Pharyngitis, cellulitis, and impetigo

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17
Q

Gram-negative organisms can be classified into what four shapes?

A

Diplococci, coccoid rods, rods, and comma-shaped

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18
Q

What is another name for leprosy?

A

Hansen disease

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19
Q

Streptococcus agalactiae is bacitracin ____ (sensitive/resistant) and ____ (α/β/γ)-hemolytic.

A

Resistant; β

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20
Q

Name four clinically important mycobacteria.

A

M. tuberculosis, M. kansasii, M. avium-intracellulare, and M. leprae

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21
Q

Enterococci (E. faecalis, E. faecium) cause urinary tract infections, subacute endocarditis, and ____.

A

Biliary tract infections

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22
Q

In a nonimmune host (e.g., a child), what kind of tuberculosis occurs after infection with Mycobacterium tuberculosis?

A

Primary tuberculosis

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23
Q

A patient with colon cancer develops a Streptococcus bovis infection. What two complications are possible?

A

Bacteremia and subacute endocarditis

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24
Q

A child has pseudomembranous pharyngitis and diffuse lymphadenopathy. What should be used to culture the suspected infectious agent?

A

Cystine-tellurite agar, on which Corynebacterium diphtheriae grows

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25
Q

Name three spore formers that are not found in soil.

A

Bacillus cereus, Clostridium botulinum, and Coxiella burnetii

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26
Q

A pregnant woman is diagnosed with Listeria monocytogenes infection. What present and future complications may result from this infection?

A

Present: amnionitis, septicemia, and spontaneous abortion; future: granulomatosis infantiseptica and neonatal meningitis

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27
Q

Which bacteria are gram-positive, spore-forming, obligate anaerobic bacilli?

A

Clostridium spp.

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28
Q

What non–lactose-fermenting, gram-negative rod is commonly associated with wound and burn infections?

A

Pseudomonas aeruginosa

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29
Q

Neisseria meningitidis ____ (does/does not) have a vaccine; Neisseria gonorrhea ____ (does/does not) have a vaccine.

A

Does; does not—note that type B N. meningitidis also has no vaccine

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30
Q

A patient has rapidly expanding necrosis on her leg; S. pyogenes is suspected. This strain of S. pyogenes has what protein?

A

M protein, present in some strains of S. pyogenes, can evade phagocytosis and rapidly move through tissue, causing necrosis

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31
Q

Name four organisms that are gram-negative, coccoid rods.

A

Haemophilus influenzae, Bordetella pertussis, Pasteurella, and Brucella

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32
Q

Inhalation of Bacillus anthracis spores leads to what symptoms?

A

Flu-like symptoms, which rapidly progress to fever, mediastinitis, pulmonary hemorrhage, and shoc

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33
Q

Name the animal reservoir for Mycobacterium leprae in the United States.

A

Armadillos

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34
Q

What structure of gram-negative bacilli inhibits the entry of penicillin G and vancomycin?

A

The outer membrane

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35
Q

You culture two different α-hemolytic species. What is the catalase and optochin status of each?

A

Streptococcus pneumoniae is optochin sensitive and Streptococcus viridans is resistant; both are catalase negative

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36
Q

In what population does group B strep (Streptococcus agalactiae) cause pneumonia, meningitis, and sepsis?

A

Babies (group B for babies)

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37
Q

Most lactose-fermenting enteric bacteria grow ____ (color) colonies on EMB agar, except E. coli, which grows ____ with a ____ sheen.

A

Purple or black; purple; green

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38
Q

What is the method of transmission of Haemophilus influenzae?

A

Aerosol transmission

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39
Q

A patient has a biliary tract infection due to Lancefield group D cocci. What lab test can differentiate enterococci from nonenterococci?

A

Enterococci grow in 6.5% sodium chloride and bile; nonenterococci can grow only in bile

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40
Q

In a partially immune, hypersensitized host, what kind of tuberculosis occurs after reinfection with Mycobacterium tuberculosis?

A

Secondary tuberculosis

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41
Q

Which β-hemolytic organism has tumbling motility, causes meningitis in newborns, and is found in unpasteurized milk?

A

Listeria monocytogenes

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42
Q

Which is an anaerobe: Actinomyces israelii or Nocardia asteroides?

A

Actinomyces israelii

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43
Q

A patient develops bacteremia, and culture confirms an agent that produces biofilms and is novobiocin sensitive. Name the most likely agent.

A

Staphylococcus epidermidis

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44
Q

Streptococcus bovis infection is associated with what type of cancer?

A

Colon cancer (bovis in the blood = cancer in the colon)

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45
Q

How is Legionnaire disease transmitted?

A

Aerosol transmission from an environmental water source; no person-to-person transmission

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46
Q

The symptoms of diphtheria are caused by what kind of toxin? How does the toxin inhibit protein synthesis?

A

Exotoxin (encoded on the β-prophage); by the ADP ribosylation of elongation factor 2

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47
Q

____ is an aerobic, gram-positive, acid-fast branching filament; ____ is anaerobic and not acid-fast stainable.

A

Nocardia; Actinomyces

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48
Q

Listeria monocytogenes infection can lead to meningitis in what two populations? What is the empirical treatment of meningitis for them?

A

Neonates and the immunocompromised; ampicillin is the empiric treatment

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49
Q

Group A streptococci are bacitracin ____ (resistant/sensitive); group B streptococci are bacitracin ____ (resistant/sensitive).

A

Sensitive; resistant

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50
Q

Some bacteria can form spores at the end of the stationary phase. Explain how spore formation is beneficial for bacterial survival.

A

Spores are highly resistant to heat/chemicals, and are not metabolically active and thus enable survival in nutrient-poor settings

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51
Q

Streptococcus pneumoniae sepsis occurs at a higher rate in which two patient populations?

A

Sickle cell anemia and asplenic patients

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52
Q

Name five inflammatory diseases that can result from infection with Staphylococcus aureus.

A

Skin infections, organ abscesses, pneumonia (often after influenza virus infection), endocarditis, and osteomyelitis

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53
Q

Name four Clostridia species that produce exotoxins.

A

Clostridium perfringens, Clostridium botulinum, Clostridium tetani, and Clostridium difficile

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54
Q

What are the two types of presentations with Bacillus cereus infection?

A

Emetic type and diarrheal type

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55
Q

Which test distinguishes α-hemolytic Streptococcus pneumoniae from Streptococcus viridans?

A

Optochin sensitivity test (S. viridans live in the mouth, as they are not afraid of-the-chin [op-to-chin resistant])

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56
Q

Name two ways Streptococcus pneumoniae evades the immune system.

A

Immunoglobulin A protease and encapsulation

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57
Q

Name two examples of α-hemolytic bacteria. How do these bacteria appear on blood agar?

A

Streptococcus pneumoniae and viridans streptococci; they form green rings around colonies

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58
Q

Lancefield grouping is based on differences in what component of the bacteria?

A

C carbohydrate on the bacterial cell wall

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59
Q

You culture a sputum sample, suspecting either Staphylococcus or Streptococcus. With which two methods can you differentiate the bacteria?

A

Both are gram-positive cocci, but staph is catalase positive and strep is catalase negative; strep grows in chains and staph in clusters

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60
Q

What kind of medium is used to grow Legionella pneumophila?

A

Charcoal yeast extract culture with iron and cysteine

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61
Q

Which is a weakly acid-fast aerobe in soil: Actinomyces israelii or Nocardia asteroides?

A

Nocardia asteroides

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62
Q

Name the enzyme produced by E. coli that breaks down lactose into glucose and galactose.

A

β-galactosidase

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63
Q

Exotoxins produced by Streptococcus pyogenes can cause which three conditions?

A

Scarlet fever (erythrogenic/pyogenic toxin), toxic shock–like syndrome (toxic shock syndrome toxin), and necrotizing fasciitis

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64
Q

How is Helicobacter pylori different from other oxidase-positive, comma-shaped, gram-negative bacteria?

A

Helicobacter pylori produces urease

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65
Q

Which β-hemolytic organism is both catalase and coagulase positive?

A

Staphylococcus aureus

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66
Q

Pseudomonas aeruginosa exhibits what distinctive color and odor?

A

Blue-green color (due to pyocyanin) with a grape-like odor

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67
Q

Because Mycobacterium leprae likes cool temperatures, it tends to infect what areas of the body?

A

The skin and the superficial nerves

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68
Q

N. meningitidis and N. gonorrhoeae both ferment what type of sugar and produce which type of immunoglobulin protease?

A

Both ferment glucose and produce IgA protease

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69
Q

Streptococcus viridans is optochin ____ (resistant/sensitive); Streptococcus pneumoniae is optochin ____ (resistant/sensitive).

A

Resistant; sensitive (ovrps [overpass]: optochin, viridans resistant and Pneumoniae sensitive)

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70
Q

What two mycobacterial species are often resistant to multiple drugs?

A

Mycobacterium tuberculosis and Mycobacterium avium-intracellulare

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71
Q

While scrubbing into the OR, you explain to your colleagues that it is critical to autoclave surgical equipment for what purpose?

A

To kill bacterial spores

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72
Q

What disease is caused by Listeria monocytogenes in healthy adults?

A

Mild gastroenteritis

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73
Q

Toxic shock syndrome, scalded skin syndrome, and rapid-onset food poisoning are all diseases caused by what?

A

Toxins released by Staphylococcus aureus (TSST-1, exfoliative toxin, and enterotoxin, respectively)

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74
Q

Adding Streptococcus agalactiae to a culture of S. aureus results in an enlarged area of hemolysis. Name the causative factor.

A

CAMP factor made by Streptococcus agalactiae (CAMP stands for the authors of the test, not cyclic AMP)

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75
Q

A 27-year-old man has spastic paralysis. You suspect C. tetanus infection. Name the toxin and explain its mechanism of action.

A

Tetanospasmin exotoxin; it blocks glycine and GABA (both are inhibitory neurotransmitters) release from Renshaw cells in the spinal cord

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76
Q

The emetic type of Bacillus cereus infection usually is seen with ingestion of what types of food?

A

Rice and pasta, causing nausea and vomiting within 1–5 hours

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77
Q

Which type of Haemophilus influenzae causes the most invasive disease?

A

Capsular type B

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78
Q

What are the two modes of anthrax inoculation?

A

Cutaneous and pulmonary

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79
Q

What chest x-ray finding can be seen in patients with primary but not secondary tuberculosis?

A

Ghon complex (Ghon focus, typically in mid-zone of the lung, with hilar node involvement)

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80
Q

Streptococcus pyogenes (group ____ strep) and S. agalactiae (group ____ strep) are both catalase ____ (positive/negative).

A

A; B; negative

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81
Q

What kind of virulence factor is produced by Haemophilus influenzae?

A

Immunoglobulin A protease

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82
Q

You culture a cellulitis sample suspecting a Staphylococcus species. How can you differentiate among the three main species?

A

S. aureus is coagulase positive; of the coagulase-negative species, S. epidermidis is novobiocin sensitive and S. saprophyticus is resistant

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83
Q

You determine that your patient developed a pulmonary infection from working with wool and inhaling which bacterial spores?

A

Bacillus anthracis; this patient has woolsorters’ disease

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84
Q

A colleague tells you your next patient has confirmed tetanus toxin in his blood/CNS. What symptoms do you expect this patient to exhibit?

A

Spastic paralysis, trismus (lockjaw), and risus sardonicus (sustained spasm of facial muscles resulting in a ““permanent grin””)

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85
Q

What symptoms are associated with the diarrheal type of Bacillus cereus infection?

A

Nonbloody, watery diarrhea and GI pain (within 8–18 hours).

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86
Q

Which three soil-dwelling, gram-positive rods form spores?

A

Bacillus anthracis, Clostridium perfringens, and Clostridium tetani

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87
Q

You counsel your patients that they can prevent diphtheria by receiving what?

A

Toxoid vaccine; usually coadministered with tetanus vaccine

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88
Q

A pregnant patient wants to know how to avoid contracting Listeria monocytogenes. How do you counsel her?

A

Avoid ingestion of unpasteurized milk/cheese and deli meats

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89
Q

Describe the lesions caused by Actinomyces israelii.

A

Oral/facial abscesses that may drain through sinus tracts—forms yellow ““sulfur granules””

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90
Q

What is a common infection source for Pseudomonas aeruginosa?

A

Water, such as in swimmer’s ear and hot tub folliculitis

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91
Q

Neisseria meningitidis ____ (does/does not) ferment maltose; Neisseria gonorrhoeae____ (does/does not) ferment maltose.

A

Does; does not

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92
Q

What type of hemolysis is induced by Enterococci?

A

Enterococcus species exhibit variable hemolysis

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93
Q

What type of lesion is seen on x-ray of the lung fields of a patient with secondary tuberculosis?

A

A cavitary lesion in the upper lobe

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94
Q

A woman leaves her tampon in for too long and develops an infection that leads to shock. What bacterial toxin is likely responsible?

A

TSST-1 produced by Staphylococcus aureus (this can also happen with nasal tampons)

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95
Q

A 25-year-old pregnant woman presents at week 36 of gestation. What bacterium should you screen for at this time?

A

Streptococcus agalactiae, which colonizes the vagina and can be transmitted to the neonate during delivery—screen at 35–37 weeks

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96
Q

A 75-year-old smoker has mild flu-like symptoms. Labs show hyponatremia. Antigen is detected in the urine. Diagnosis and treatment?

A

The patient likely has Pontiac fever caused by Legionella pneumophila; treat with macrolide or quinolone

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97
Q

A patient has pulmonary TB–like symptoms but no Mycobacterium tuberculosis infection. What is the likely causative organism?

A

Mycobacterium kansasii

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98
Q

What is a common source of Pasteurella infections?

A

Animal bites

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99
Q

A 4-year-old boy with recent pharyngitis has tea-colored urine. Name the illness and causative agent. What other illness(es) is/are a risk?

A

Acute glomerulonephritis; S. pyogenes; rheumatic fever & pharyngitis (pharyngitis can cause rheumatic phever [fever] & glomerulonephritis)

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100
Q

A patient presents with nasal collapse, loss of eyebrows, and lumpy skin. Give the treatment plan, including medications and duration.

A

This patient has the lepromatous form of Hansen disease/leprosy; treat with dapsone, rifampin, and clofazimine for 2–5 years

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101
Q

Chest x-ray of a 70-year-old man with a cough shows left lower lobe pneumonia. What hemolysis pattern does the most likely pathogen exhibit?

A

Streptococcus pneumoniae is the most common cause of pneumonia; it exhibits green partial (α-) hemolysis

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102
Q

Streptococcus pyogenes is bacitracin ____ (sensitive/resistant); S. agalactiae is bacitracin ____ (sensitive/resistant).

A

Sensitive; resistant

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103
Q

A patient contracts a nosocomial infection, and it is notably resistant to vancomycin therapy. What is the likely causative organism?

A

Vancomycin-resistant enterococci (VRE)—VRE are important causes of nosocomial infections

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104
Q

What is the toxin that causes emesis in Bacillus cereus infections?

A

Cereulide, a preformed toxin

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105
Q

A pregnant lady (37 weeks) has a positive hippurate test. Cultures show bacitracin resistance and β-hemolytic bacteria.You give ____ prophylaxis.

A

Intrapartum penicillin prophylaxis for Streptococcus agalactiae infection to prevent neonatal meningitis, pneumonia, and sepsis

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106
Q

You suspect that a patient has Haemophilus influenzae. What medium should you use to grow the culture?

A

Chocolate agar with factors V (NAD+) and X (hematin)

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107
Q

Name the four possible outcomes of primary tuberculosis.

A

Fibrous healing, progressive lung disease, severe bacteremia, and preallergic lymphatic/hematogenous dissemination

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108
Q

The mnemonic ABCDEFG is useful for remembering key information about Corynebacterium diphtheriae. State this mnemonic.

A

ADP ribosylation; beta- (β-)prophage; Vorynebacterium diphtheriae; elongation factor 2; granules

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109
Q

A teen presents with fever, vomiting, rash, desquamation, and shock. Explain the pathogenesis of the causative toxin.

A

This teen likely has toxic shock syndrome due to TSST-1—a superantigen that binds MHC II and TCR, resulting in polyclonal T-cell activation

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110
Q

Name two clinical syndromes caused by Legionella pneumophila.

A

Legionnaire disease and Pontiac fever

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111
Q

A patient had recent S. pyogenes infection. You ask the lab to test for antibodies to M protein to assess risk of what condition?

A

Rheumatic fever—antibodies to M protein enhance host defense against S. pyogenes but can result in rheumatic fever

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112
Q

Bacillus anthracis can be diagnosed based on which unique microscopic cellular morphology?

A

Bacillus anthracis synthesizes a polypeptide capsule (contains D-glutamate)

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113
Q

What are common routes of transmission for Listeria monocytogenes infection?

A

Transplacental transmission or vaginal transmission during birth

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114
Q

An AIDS patient develops disseminated Mycobacterium avium-intracellulare infection. What drug could have likely prevented this?

A

Azithromycin, which is used for prophylaxis, particularly in patients with AIDS

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115
Q

Name two gram-negative cocci and how to differentiate them.

A

Neisseria meningitidis, which ferments maltose, and Neisseria gonorrhoeae, which does not ferment maltose

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116
Q

What five types of infection can Neisseria gonorrhoeae cause?

A

Gonorrhea, pelvic inflammatory disease, septic arthritis, Fitz-Hugh–Curtis syndrome, and neonatal conjunctivitis

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117
Q

A patient develops flaccid paralysis after eating food from a poorly sealed can. What is the likely causative organism?

A

Clostridium botulinum

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118
Q

What type of toxin causes fever and hypotension in Pseudomonas sepsis?

A

Endotoxin

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119
Q

What are the two forms of Hansen’s disease?

A

Lepromatous and tuberculoid

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120
Q

Actinomyces is found in ____ (normal oral flora/soil) and Nocardia is found in ____ (normal oral flora/soil).

A

Normal oral flora; soil

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121
Q

A woman with PID caused by Neisseria gonorrhoeae develops severe RUQ pain from liver capsule inflammation. What complication is this?

A

Fitz-Hugh–Curtis syndrome

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122
Q

What are the characteristics of the toxin produced by Clostridium botulinum?

A

Preformed, heat-labile toxin

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123
Q

A patient develops subacute endocarditis after a gastric bypass surgery. What is the likely causative organism?

A

Enterococci (group D streptococci)—patients are prone to such infections after gastrointestinal and genitourinary procedures

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124
Q

Exotoxin A produced by Pseudomonas aeruginosa inactivates what human enzyme used in protein synthesis?

A

Elongation factor 2

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125
Q

Differentiate Legionnaire disease from Pontiac fever.

A

Legionnaire disease exhibits severe pneumonia with fever, GI, and CNS symptoms; Pontiac fever is a mild flu-like syndrome

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126
Q

In virulent M. tuberculosis strains, ____ inhibits macrophage maturation and induces TNF-α release; ____ inhibit phagolysosome fusion.

A

Cord factor; sulfatides (surface glycolipids)

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127
Q

A young boy with primary tuberculosis develops severe bacteremia. What type of tuberculosis might he develop subsequently?

A

Miliary tuberculosis, characterized by small granulomas in multiple organs

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128
Q

How does Listeria monocytogenes move between cells to avoid the attack of host antibodies?

A

They form ““rocket tails”” via actin polymerization that allow transport through the cytoplasm and into cell membranes

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129
Q

An unvaccinated boy gets meningitis. Bacteria grow on chocolate agar with factors V and X. Diagnosis and treatment plan?

A

Haemophilus influenzae infection; treatment is ceftriaxone, and close contacts should receive rifampin prophylaxis

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130
Q

On agar, partial (green) hemolysis is ___-hemolysis, complete (clear) hemolysis is ___-hemolysis, and absent hemolysis is ___-hemolysis.

A

α; β; γ

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131
Q

A man gets food poisoning soon after eating food contaminated with S. aureus. Name the toxin. What is its incubation period?

A

Preformed enterotoxins; incubation period is 2–6 hours

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132
Q

Which of the two forms of leprosy indicates failed cell-mediated immunity and has a worse prognosis?

A

Lepromatous = lethal

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133
Q

Gram-negative rods are differentiated by their ability to ferment what substance?

A

Lactose

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134
Q

You suspect that your patient has had a recent Streptococcus pyogenes infection. What blood test do you order?

A

Anti–streptolysin O titer

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135
Q

You suspect M. leprae infection in your patient. What characteristic of M. leprae complicates your diagnostic testing options?

A

Mycobacterium leprae cannot be grown in vitro

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136
Q

What happens to patients with primary tuberculosis who develop preallergic lymphatic/hematogenous dissemination?

A

They develop dormant tubercle bacilli in several organs and are susceptible to reactivation of the disease during their adult life

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137
Q

What are the symptoms of tuberculosis?

A

Fever, night sweats, weight loss, hemoptysis

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138
Q

Name three fast lactose-fermenting, gram-negative rods.

A

Klebsiella, E. coli, and Enterobacter

139
Q

A Streptococcus culture exhibits α-hemolysis. How will you further determine the species?

A

S. pneumoniae and S. viridans are α-hemolytic, but only S. pneumoniae has a capsule and is optochin sensitive

140
Q

What protein is altered in MRSA, resulting in resistance to β-lactams? Name two drugs that are useless against MRSA as a result.

A

Penicillin-binding protein; methicillin and nafcillin

141
Q

Two smokers in their 60’s staying in a hotel develop fever, cough, and dyspnea. What test do you order to evaluate for Legionella?

A

Urine Legionella antigen

142
Q

A colleague tells you a patient in the ED meets the Jones criteria. Explain the criteria and name the diagnosis.

A

Joints (polyarthritis), heart (carditis), nb>odules (subcutaneous), erythema marginatum, Sydenham chorea; rheumatic fever

143
Q

A patient has an Actinomyces infection; another has a Nocardia infection. How do you treat each patient?

A

Actinomyces is treated with penicillin; Nocardia is treated with sulfonamides

144
Q

A young woman presents to your office with a UTI caused by Enterococcus faecalis. This bacterium is resistant to what antibiotic?

A

Penicillin G

145
Q

What three clinical syndromes can Neisseria meningitidis cause?

A

Meningococcemia, meningitis, and Waterhouse-Friderichsen syndrome

146
Q

A 2-year-old boy unvaccinated against Haemophilus influenzae has the flu. Can H. influenzae be the cause?

A

No, as influenza virus causes the flu

147
Q

What characteristic microscopic finding can you see while examining Listeria monocytogenes under the microscope?

A

Tumbling motility—Listeria monocytogenes also is the only gram-positive organism that produces LPS

148
Q

How does the toxin produced by Clostridium botulinum cause flaccid paralysis?

A

It inhibits acetylcholine release at the neuromuscular junction.

149
Q

A child with cystic fibrosis has pneumonia and coughs up blue-green sputum. What is the likely causative organism?

A

Pseudomonas aeruginosa

150
Q

A patient presents with lesions over the skin that are diffuse and communicable. What form of Hansen disease is this?

A

Lepromatous

151
Q

A Streptococcus culture exhibits complete hemolysis. How will you further determine the species?

A

Both S. pyogenes and S. agalactiae are β-hemolytic—S. pyogenes is bacitracin sensitive and S. agalactiae is resistant

152
Q

What is the treatment for Listeria monocytogenes infection in infants and immunocompromised patients? In otherwise healthy adults?

A

Ampicillin in infants and immunocompromised patients; gastroenteritis in healthy adults usually is self-limited and requires no treatment

153
Q

Pseudomonas aeruginosa is an ____ (aerobic/anaerobic) gram- ____ (positive/negative) ____ (rod/cocci).

A

Aerobic; negative; rod

154
Q

A patient with meningococcemia develops acute hypotension, petechiae, and bilateral adrenal hemorrhages. Name the complication.

A

Waterhouse-Friderichsen syndrome

155
Q

Describe the vaccine used against Haemophilus influenzae

A

Contains type B capsular polysaccharide (polyribosylribitol phosphate), conjugated to diphtheria toxoid or other proteins

156
Q

A 15-year-old girl presents with a strawberry tongue, sore throat, fever, and a red rash sparing the face. Name the causative agent.

A

Streptococcus pyogenes causes scarlet fever (strawberry tongue, scarlet rash, and circumoral pallor)

157
Q

Name six common sites of extrapulmonary tuberculosis. Infection at which site causes Pott disease?

A

Central nervous system, lymphatics, kidneys, GI tract, adrenals, and vertebral bodies; infection in vertebral bodies causes Pott disease

158
Q

Name two slow lactose-fermenting, gram-negative rods.

A

Citrobacter and Serratia

159
Q

A patient has an abscess draining via the sinuses containing fluid with yellow ““sulfur granules.”” What is the causative organism?

A

Actinomyces israelii

160
Q

Adults contract botulism by ingesting ____ (preformed toxin/spores); infants develop botulism by ingesting ____ (preformed toxin/spores).

A

Preformed toxin; spores, often in honey (botulism is from bad bottles of food and honey [causes floppy baby syndrome])

161
Q

The Haemophilus influenzae vaccine is given to which age group?

A

Infants 2#8211;18 months of age

162
Q

Describe the clinical significance of Staphylococcus aureus being coagulase positive.

A

It allows for the organism to form a fibrin clot around itself, leading toŽ abscess formation

163
Q

A 4-year-old boy presents with a puffy face and tea-colored urine. On examination, there is evidence of what recent skin infection?

A

Impetigo, caused by Streptococcus pyogenes, more commonly precedes glomerulonephritis than pharyngitis

164
Q

How is Neisseria gonorrhoeae transmitted? How can it be prevented?

A

Sexually transmitted; condoms prevent sexual transmission, and erythromycin ointment prevents neonatal transmission

165
Q

A patient has an intact T-cell response and only a few hypoesthetic nodules on his skin. What form of Hansen disease is this?

A

Tuberculoid

166
Q

What two conditions can tuberculosis lead to following central nervous system invasion?

A

Parenchymal tuberculoma and meningitis

167
Q

Among lactose nonfermenters, which gram-negative rod is oxidase positive?

A

Pseudomonas

168
Q

Is Pseudomonas aeruginosa oxidase positive or oxidase negative?

A

Oxidase positive

169
Q

Your patient develops gas gangrene and hemolysis due to the effects of the α-toxin produced by what infectious organism?

A

Clostridium perfringens (perfringens perforates a gangrenous leg)

170
Q

Name two streptococci that are γ-hemolytic.

A

Enterococcus and non-Enterococcus species (e.g., Streptococcus bovis)

171
Q

Among lactose nonfermenters, which gram-negative rods are oxidase negative?

A

Shigella, Salmonella, Proteus, Yersinia

172
Q

Your culture of gram-positive, catalase-negative cocci exhibits no hemolysis. How will you further determine the species?

A

Nonenterococci species (e.g., Streptococcus bovis) will grow in bile but not in 6.5% NaCl; enterococci are the opposite

173
Q

What is the effect of the toxin produced by Clostridium perfringens?

A

α-toxin (lecithinase) causes myonecrosis, gas gangrene, and hemolysis

174
Q

How is Neisseria meningitidis transmitted?

A

Respiratory and oral secretions

175
Q

You are terrified of S. aureus food poisoning and overcook your food. Does this help?

A

No, as enterotoxin is heat stable and not destroyed by cooking

176
Q

A 4-year-old boy is febrile, lethargic, stridorous, and drooling. Likely diagnosis? What vaccine could have prevented it?

A

The patient likely has epiglottitis, which can be prevented with Haemophilus influenzae type B vaccine

177
Q

In what populations does tuberculosis most frequently develop into progressive lung disease?

A

HIV-positive or malnourished individuals

178
Q

Name seven syndromes caused by Pseudomonas.

A

Pneumonia, sepsis, external otitis, UTI, drug use, diabetic osteomyelitis, and hot tub folliculitis

179
Q

A patient presents with impetigo. The most likely causative organism is sensitive to which topical antibiotic?

A

Impetigo is caused by Streptococcus pyogenes; bacitracin

180
Q

A diabetic patient visits your office with fever. You discovered that he has osteomyelitis. What is the likely causative organism?

A

Pseudomonas aeruginosa

181
Q

Of the oxidase-positive, comma-shaped, gram-negative bacteria, ____ grows in 42°C whereas ____ grows in alkaline media.

A

Campylobacter jejuni; Vibrio cholerae

182
Q

Some α-hemolytic cocci are bile soluble. Name the bug. What is the bile doing to the organism? Are any α-hemolytic bugs not bile soluble?

A

The bug is S. pneumoniae; the bile is lysing the bacteria; viridans streptococci (also α-hemolytic) are not lysed by bile

183
Q

A patient has a positive purified purine derivative (PPD) test. Name three possible explanations for this result.

A

Current tuberculosis infection, previous exposure, and BCG vaccination

184
Q

How do you distinguish S. aureus from streptococci in the lab?

A

Staphylococci make catalase, whereas streptococci do not (staph make catalase because they have more ““staff””

185
Q

Why is it not possible to make a vaccine against Neisseria gonorrhoeae?

A

Because of the rapid antigenic variation of the pilus proteins

186
Q

A patient exhibits severe diarrhea. Exam reveals pseudomembranous colitis. Culture shows gram-positive, spore-forming bacilli. Diagnosis?

A

Infection with Clostridium difficile (difficile causes diarrhea)

187
Q

A healthcare worker was potentially exposed to N. meningitidis. What prophylaxis treatment should be offered?

A

Rifampin, ciprofloxacin, or ceftriaxone

188
Q

Name three types of infections caused by nontypeable strains of Haemophilus influenzae.

A

Otitis media, conjunctivitis, and bronchitis (all mucosal infections)

189
Q

A burn victim develops black lesions on his skin. You order treatment with aminoglycosides and piperacillin to eradicate what bacteria?

A

Pseudomonas aeruginosa—black lesions on skin are a sign of sepsis

190
Q

Which two antibiotics are you wary of prescribing, as they can promote pseudomembranous colitis?

A

Clindamycin and ampicillin

191
Q

A patient with sarcoidosis has a negative purified protein derivative (PPD) test, but you still suspect tuberculosis. Justify your thinking.

A

This patient may be anergic; anergy can result from steroids, malnutrition, immunocompromised states, or sarcoidosis, causing a negative PPD

192
Q

Which Clostridium difficile toxin binds to the brush border of the gut?

A

Toxin A, which is an enterotoxin

193
Q

A patient who has had the BCG vaccine presents for a test for tuberculosis infection. What is the most appropriate test to order?

A

Interferon-γ release assay (IGRA)—a more specific test that has fewer false-positive results vs. BCG vaccination

194
Q

What is the treatment for Neisseria gonorrhoeae and Neisseria meningitidis?

A

N. gonorrhoeae: ceftriaxone (plus azithromycin or doxycycline for possible chlamydia); N. meningitidis: ceftriaxone or penicillin G

195
Q

What cellular changes caused by toxin B (cytotoxin) do you see in a patient with Clostridium difficile infection?

A

Destruction of cell cytoskeletal organization

196
Q

How do you diagnose Clostridium difficile?

A

By the presence of toxin A (enterotoxin) and/or toxin B (cytotoxin) in stool

197
Q

Your patient has recurring C. difficile infection. What type of treatment would you recommend that may prevent relapse?

A

Fecal transplant

198
Q

Your patient developed pseudomembranous colitis caused by Clostridium difficile. Which antibiotic do you prescribe?

A

Metronidazole or oral vancomycin

199
Q

A patient has pupil constriction with accommodation but no reaction to light. What is this finding and what is it associated with?

A

Argyll Robertson pupil; tertiary syphilis

200
Q

A 73-year-old woman develops cystitis and pyelonephritis from an E. coli infection. What virulence factor is responsible?

A

Fimbriae

201
Q

What bacterium is most commonly implicated in ““walking”” pneumonia?

A

Mycoplasma pneumoniae

202
Q

Where geographically are Chlamydia trachomatis serotypes A, B, and C found? What do they cause?

A

ABC: they are found in Africa, cause Blindness, and result in Chronic infection

203
Q

During its life cycle, what form of chlamydia is infectious?

A

The rlementary body (small, dense), which rnters the cell by endocytosis

204
Q

What is the treatment of choice for all rickettsial infections?

A

Doxycycline

205
Q

How is anaplasmosis transmitted?

A

Ixodes ticks that dwell on deer and mice

206
Q

A patient receives intramuscular penicillin for syphilis and later feels like he has the flu. What causes this phenomenon?

A

Jarisch-Herxheimer reaction, a flu-like syndrome following administration of antibiotic that is due to killed bacteria releasing pyrogens

207
Q

Which conditions give biologic false-positive results on the Venereal Disease Research Laboratory (VDRL) test? What does it screen for?

A

VDRL: viruses (mononucleosis, hepatitis), drugs, rheumatic fever, lupus, leprosy

208
Q

What bacterium causes Lyme disease?

A

Borrelia burgdorferi

209
Q

A swimmer in a cove develops fever, fatigue, body aches, photophobia, and conjunctival suffusion. What is the water contaminated with?

A

Animal urine with Leptospira interrogans, which causes leptospirosis

210
Q

What are the three spirochete species that most commonly infect humans?

A

Borrelia, Leptospira, and Treponema (BLT)

211
Q

A man with a chronic peptic ulcer has a positive urease breath test. What is the first-line treatment?

A

Triple therapy for H. pylori—treated with proton pump inhibitor, clarithromycin, or amoxicillin or metronidazole

212
Q

An alcoholic passes out and aspirates his vomit. A lung abscess that subsequently develops is most likely caused by what pathogen?

A

Klebsiella infection (4 A’s = Aspiration pneumonia, Abscess in lungs and liver, Alcoholics, diAbetics)

213
Q

What are the usual modes of transmission of Yersinia enterocolitica?

A

Pet feces (e.g., from puppies) and contaminated milk or pork

214
Q

A traveler to a developing country develops rice-water diarrhea due to a pathogen that acts by what mechanism?

A

Vibrio cholerae releases a toxin that activates Gs and increases cAMP

215
Q

Which of the following has flagella: Salmonella or Shigella? What is the pathologic significance?

A

Salmonella (““salmon swim””); flagella enable hematogenous dissemination

216
Q

A 5-year-old boy eats raw beef and develops bloody diarrhea. Two weeks later he cannot move his legs. Why and what is the likely infection?

A

He likely has Guillain-Barré syndrome caused by Campylobacter jejuni

217
Q

A positive Venereal Disease Research Laboratory (VDRL) test indicates that antibodies have formed against what molecule?

A

Beef cardiolipin

218
Q

What kind of discharge is produced in vaginosis caused by Gardnerella vaginalis?

A

Gray vaginal discharge with a fishy odor

219
Q

A 9-year-old boy has progressively ascending weakness. If this is related to an infection, what did he most likely eat to cause it?

A

Poultry, meat, and unpasteurized milk can harbor Campylobacter jejuni, which can cause Guillain-Barrésyndrome

220
Q

A patient develops cat scratch fever after being clawed by her kitten. What is the causative pathogen?

A

Bartonella spp.

221
Q

By culturing Campylobacter jejuni and Vibrio cholerae, how can the two be distinguished as a cause of infection?

A

Campylobacter jejuni grows at 42°C, and Vibrio cholerae grows in alkaline media

222
Q

What property of Klebsiella gives it the description of ““mucoid””?

A

Polysaccharide capsule

223
Q

The differential diagnosis includes Crohn disease and appendicitis, but the real problem is caused by Yersinia enterocolitica. What is it?

A

Mesenteric adenitis

224
Q

Helicobacter pylori causes what two pathologies in the gastrointestinal tract?

A

Gastritis and peptic ulcers (especially duodenal)

225
Q

Rickettsiae are transmitted by what type of vector?

A

Arthropods (except Coxiella, which is transmitted by aerosol)

226
Q

Are humans and primates the only reservoirs for Shigella or Salmonella?

A

Shigella—many animals serve as reservoirs for Salmonella (salmon = animal)

227
Q

What are the symptoms of Mycoplasma pneumoniae pneumonia?

A

Insidious onset, headache, nonproductive cough, diffuse interstitial infiltrates on chest x-ray

228
Q

What is the only spirochete that can be visualized by light microscopy with aniline dyes (Wright or Giemsa stain)?

A

Borrelia (big size)

229
Q

A surfer is diagnosed with leptospirosis because of the history of present illness and what symptoms?

A

Flu-like symptoms, jaundice, and photophobia with conjunctival suffusion suggest leptospirosis

230
Q

A neonate develops pneumonia and meningitis due to an E. coli infection. What virulence factor is responsible?

A

K capsule

231
Q

What vector transmits the organisms that cause Lyme disease and babesiosis?

A

The Ixodes tick

232
Q

During its life cycle, what form of chlamydia replicates by fission in the cell?

A

The reticulate body replicates by fission

233
Q

A man has a painless sore on his penis and rash developing on his palms. What is the treatment of choice?

A

Treat with penicillin G for syphilis

234
Q

Which Chlamydia trachomatis serotypes cause urethritis, PID, ectopic pregnancy, neonatal pneumonia, and neonatal conjunctivitis?

A

Types D–K

235
Q

What is the best treatment for cholera?

A

Prompt oral rehydration

236
Q

Is Gardnerella vaginalis considered a sexually transmitted disease?

A

No—however, it is associated with sexual activity

237
Q

Which spirochete species is visualized by dark-field microscopy?

A

Treponema, which causes syphilis

238
Q

A patient with E. coli infection develops a severe complication due to lipopolysaccharide endotoxin exposure. What complication?

A

Septic shock

239
Q

In culturing Campylobacter jejuni, what observations help to identify it as a cause of infection?

A

It is comma or S shaped, is oxidase positive, and grows at 42°C

240
Q

A patient has this severe form of leptospirosis with elevated bilirubin and creatinine, fever, hemorrhage, and low hemoglobin. Diagnosis?

A

Weil disease (icterohemorrhagic leptospirosis)

241
Q

Rocky Mountain spotted fever is endemic to what area?

A

South Atlantic states, especially North Carolina

242
Q

What hematologic finding may help confirm Mycoplasma pneumoniae infection?

A

High titer of cold agglutinins (IgM), which can agglutinate or lyse RBCs

243
Q

An immunocompromised man gets a Bartonella infection. What complication do you mistake for Kaposi sarcoma?

A

Bacillary angiomatosis

244
Q

How does Helicobacter pylori thrive as a pathogen in the stomach and cause peptic ulcers?

A

It produces an alkaline environment

245
Q

In what stage of syphilis does the disease become disseminated?

A

Secondary syphilis, with constitutional symptoms and skin manifestations—think secondary syphilis = systemic

246
Q

A diabetic patient diagnosed with pneumonia has red ““currant jelly”” sputum. The likely pathogen causes what other type of infection?

A

The pneumonia pathogen is most likely Klebsiella, which also can cause nosocomial urinary tract infections

247
Q

Which Chlamydia trachomatis serotypes cause lymphogranuloma venereum?

A

Types L1, L2, and L3

248
Q

What are one biochemical similarity and one biochemical difference between Shigella and Salmonella?

A

Salmonella produces hydrogen sulfide, but Shigella does not; neither can ferment lactose

249
Q

The vector of the organism that causes Lyme disease relies on what animal as part of its life cycle?

A

Mice play an important role in the life cycle of the Ixodes tick, and serve as a natural reservoir

250
Q

When is neonatal chlamydia acquired?

A

As the infant passes through an infected birth canal

251
Q

Secondary syphilis presents with what type of skin manifestations?

A

A maculopapular rash on palms and soles and condylomata lata on the genitals

252
Q

You suspect bacterial vaginosis in a patient. What would you expect to see in a wet prep of her vaginal discharge?

A

Classically, clue cells, or vaginal epithelial cells covered with bacteria

253
Q

How does enteroinvasive E. coli (EIEC) cause dysentery?

A

EIEC invades the mucosa of the intestine, causing necrosis and inflammation, which results in dysentry

254
Q

Salmonella infection should be treated with which antibiotics?

A

Salmonellosis should not be treated with antibiotics, as doing so can prolong symptoms

255
Q

Which two chlamydial species cause atypical pneumonia, and how are they transmitted?

A

C. pneumoniae and C. psittaci; aerosol transmission

256
Q

What is the vector for the pathogen that causes Lyme disease?

A

Ixodes tick, which carries Borrelia burgdorferi

257
Q

Mycoplasma pneumoniae can be grown on what medium?

A

Eaton agar

258
Q

A camper presents with a headache, fever, and rash that started on the wrists and ankles. What is the diagnosis and causative organism?

A

Rocky Mountain spotted fever; it is caused by Rickettsia rickettsii

259
Q

A 20-year-old patient develops bloody diarrhea from contaminated chicken, and complains of dysuria and sore knees. What else is possible?

A

He possibly has Guillain-Barré syndrome from Campylobacter infection

260
Q

Helicobacter pylori is a risk factor for what two cancers?

A

Gastric adenocarcinoma and lymphoma

261
Q

What is the cause of azotemia and jaundice in patients with Weil disease?

A

Kidney and liver dysfunction

262
Q

A patient is diagnosed with duodenal ulcers caused by a curved gram-negative rod. What three enzymes is this bacterium positive for?

A

Catalase, oxidase, and urease

263
Q

A 35-year-old man complains of pain and swelling along the inguinal lymph nodes that have begun to ulcerate. Likely cause and treatment?

A

Chlamydia trachomatis types L1, L2, and L3; doxycycline

264
Q

What toxins of enterotoxic E. coli are responsible for traveler’s diarrhea?

A

Labile and stable toxins

265
Q

How does the pathogenicity of Salmonella differ from that of Shigella?

A

Salmonella spreads by blood with a monocytic response, and Shigella spreads cell to cell with a PMN response—both invade mucosa

266
Q

In what region of the United States is Lyme disease common?

A

The northeastern United States

267
Q

A bird trader who develops fever and dyspnea is diagnosed with an atypical pneumonia, most likely caused by what pathogen?

A

Chlamydia psittaci, which is carried by birds

268
Q

A patient diagnosed with bacterial vaginosis is prescribed metronidazole. A second medication may also be given and for what?

A

Overgrowth of vaginal anaerobic bacteria characterize bacterial vaginosis; treatment is clindamycin

269
Q

Where can treponemes be found during primary and secondary syphilis? What do you use to visualize them?

A

In chancres during primary syphilis and in condylomata lata during secondary syphilis; use dark-field microscopy to see treponemes

270
Q

What antibiotics are used to treat Mycoplasma pneumoniae infection? Why are penicillins ineffective?

A

Treatments used are macrolides, doxycycline, or fluoroquinolones; the organisms are resistant to penicillin, as they have no cell walls

271
Q

A patient is bitten by a louse and develops a recurrent fever. What bacterium is likely responsible?

A

Borrelia recurrentis

272
Q

Rickettsia ricketsii organisms are ____ (obligate/facultative) intracellular parasites, because they require which two cofactors?

A

Obligate; coenzyme A and nicotinamide adenine dinucleotide (NAD+)

273
Q

What characterizes the initial symptoms of Lyme disease?

A

Erythema chronicum migrans (expanding bull’s eye red rash), flu-like symptoms, and possibly facial nerve palsy

274
Q

A sexually active woman has PID. If it is caused by Chlamydia trachomatis, what do you see on microscopy and how do you treat?

A

Cytoplasmic inclusions on Giemsa or fluorescent antibody staining; treatment is azithromycin or doxycycline

275
Q

What is responsible for the recurrent nature of the fever caused by Borrelia recurrentis?

A

Variable surface antigens on the bacteria

276
Q

Clinically, how do Salmonella and Shigella present?

A

Salmonella can produce bloody diarrhea, and Shigella often results in bloody diarrhea

277
Q

Why are Mycoplasma pneumoniae not seen on Gram stain?

A

They have no cell walls

278
Q

What three types of E. coli do not invade the intestinal mucosa?

A

Enterohemorrhagic (EHEC), enterotoxigenic (ETC), and enteropathogenic (EPEC); only the enteroinvasive (EIEC) type invades intestinal mucosa

279
Q

A man is concerned he has syphilis. What tests do you use to screen and confirm infection?

A

To screen, use VDRL/RPR tests; confirm with FTA-ABS test

280
Q

How does enteropathogenic E. coli cause diarrhea?

A

It adheres to the apical surface and flattens villi, decreasing absorption

281
Q

A patient complains of fever, headache, and diarrhea. Physical exam reveals rose spots on his abdomen. What is the likeliest infection?

A

Typhoid fever caused by Salmonella typhi

282
Q

What characterizes the later symptoms of Lyme disease?

A

Monoarthritis of large joints, migratory polyarthritis, AV node heart block, encephalopathy, facial nerve palsy, polyneuropathy

283
Q

A dairy farmer presents with 1 week of fever that waxes and wanes. Which bacteria caused it?

A

Brucella spp. from unpasteurized dairy, which causes undulant fever

284
Q

Mycoplasma cell membranes are distinct, because they contain ____.

A

Sterols, for stability

285
Q

What is latent syphilis and when does it happen?

A

Latent syphilis is characterized by positive serology but no symptoms; it follows secondary syphilis

286
Q

What is the classic triad of symptoms caused by a Rocky Mountain spotted fever infection?

A

Headache, fever, and rash (vasculitis)

287
Q

The cell wall of chlamydia is unique because it lacks ____.

A

Muramic acid

288
Q

Which stage of syphilis is characterized by broad-based ataxia, positive Romberg sign, Charcot joints, and stroke-like symptoms?

A

Tertiary syphilis

289
Q

Does enteropathogenic E. coli (EPEC) directly cause damage or act via a toxin?

A

EPEC does not produce a toxin—it is directly pathogenic

290
Q

What is the treatment for a patient with a history of bull’s eye rash, arthritis of one knee, and facial nerve palsy?

A

Doxycycline, ceftriaxone

291
Q

A 32-year-old man complains of bloody diarrhea, which results indicate were caused by Campylobacter. How is this transmitted?

A

Fecal-oral route (consumption of undercooked meat)

292
Q

What three diseases start with a rash on the palms and soles?

A

Coxsackievirus A, Rocky Mountain spotted fever, and syphilis (you drive cars using your palms and soles)

293
Q

Why are Chlamydia species intracellular organisms?

A

Because they cannot make their own ATP

294
Q

What characterizes typhoid fever? What causes it?

A

Fever, headache, diarrhea, and abdominal rose spots; caused by Salmonella typhi

295
Q

What age group is more commonly affected by Mycoplasma pneumoniae infection? Outbreaks are frequent in what settings?

A

Individuals <30 years of age are more commonly infected; outbreaks often occur among military recruits and in prisons

296
Q

What is the causative agent for psittacosis and what are its sources?

A

Chlamydophila psittaci; sources are parrots and other birds

297
Q

Tertiary syphilis can present with what?

A

Gummas, aortitis, neurosyphilis, Argyll Robertson pupil

298
Q

A patient is bitten by a flea and develops endemic typhus. What bacterium is responsible for this disease?

A

Rickettsia typhi

299
Q

What population tends to get diarrhea following enteropathogenic E. coli infection?

A

Children (EPEC = Pediatrics)

300
Q

"”FAKE a Key Lyme pie”” is a helpful way to remember key signs/symptoms of Lyme disease. What does it stand for?

A

Facial nerve palsy, arthritis, kardiac (cardiac) block, Erythema migrans

301
Q

A traveler who becomes ill with typhoid fever can transmit it to others, because the pathogen can remain in what organ?

A

The gallbladder

302
Q

A patient with nonproductive cough and headache presents. Eaton agar grows bacteria on culture. What is the diagnosis?

A

Atypical ““walking”” pneumonia caused by Mycoplasma pneumoniae

303
Q

A patient develops pneumonia. On further questioning, he reports having recently purchased a pet parrot. What is the likely causative agent?

A

Chlamydophila psittaci, which causes psittacosis—sources are parrots and other birds

304
Q

An 18-year-old military recruit is diagnosed w/ atypical pneumonia. No organism is seen on Gram stain. What are treatment options?

A

Macrolide, doxycycline or fluoroquinolone for Mycoplasma pneumoniae, which has no cell wall and cannot be visualized on Gram stain

305
Q

A 7-year-old boy eats an undercooked burger and then develops diarrhea, oliguria, and low ____ and ____ counts.

A

RBC and platelet counts, as well as acute kidney injury—this is hemolytic-uremic syndrome due to enterohemorrhagic E. coli (EHEC)

306
Q

A boy is bitten by a human body louse and develops a rash that spreads from his trunk outward, but not to the palms or soles. Cause?

A

Epidemic typhus (think Typhus on the Trunk) from Rickettsia prowazekii

307
Q

A 42-year-old man presents with broad-based gait, positive Romberg, and Argyll Robertson pupil. How do you test for neurosyphilis?

A

Test spinal fluid via VDRL or RPR

308
Q

The rash caused by ____ (Rocky Mountain spotted fever/typhus) starts on the trunk, moving outward, sparing the palms and soles.

A

Typhus (think Rickettsii on the wrists, & typhus on the trunk

309
Q

A 24-year-old veterinary student helps deliver a lamb on a farm; 2 weeks later, he feels unwell and has a fever. What is the likely agent?

A

Coxiella burnetii, which causes Q fever, from cattle/sheep amniotic fluid aerosols

310
Q

How does E. coli O157:H7 induce thrombocytopenia, anemia, and acute renal failure?

A

The toxin causes endothelial damage on which microthrombi form, leading to hemolysis, low renal blood flow, and platelet consumption

311
Q

A patient is suffering from destruction of the vasa vasorum that you determine is due to an infection. What is the likely agent?

A

Treponema pallidum, which causes syphilis

312
Q

A 1-year-old child presents with several abnormalities; you diagnose congenital syphilis. What could these abnormalities include?

A

Saber shins, saddle nose, cranial nerve VIII deafness, Hutchinson teeth, mulberry molars

313
Q

How is ehrlichiosis acquired?

A

Bite of the lone star tick, carrying Ehrlichia chaffeensis

314
Q

What are the differences between dysentery caused by enterohemorrhagic E. coli (EHEC) vs. enteroinvasive E. coli (EIEC)?

A

EHEC produces Shiga-like toxin, which causes necrosis and inflammation; EIEC directly invades the mucosa to cause necrosis and inflammation

315
Q

A patient contracts tularemia from Francisella tularensis. How is this pathogen transmitted?

A

Tick, rabbit, deer fly

316
Q

How can you distinguish enterohemorrhagic E. coli (EHEC) from other types using a culture dish?

A

EHEC does not ferment sorbitol

317
Q

A man is bitten by a tick and has no rash, but on a blood smear, monocytes with berry-like inclusions are seen. Likely diagnosis?

A

Ehrlichiosis, characterized by the presence of morulae in monocytes—morulae are cytoplasmic inclusions that resemble berries

318
Q

An infant with saber shins and saddle nose presents with his mother. How could these manifestations have been prevented?

A

By treating the mother for syphilis early in pregnancy (transmission through the placenta usually happens after the first trimester)

319
Q

After a devastating storm, town officials worry about which bacterium, found in animal urine, might contaminate water supplies? Which?

A

Leptospira spp.

320
Q

A 31-year-old man complains of an ulcer on his penis. He tests positive on VDRL/RPR and confirmatory FTA-ABS. What is treatment of choice?

A

Penicillin G

321
Q

Anaplasmosis has ____ (monocytes/granulocytes) with morulae in cytoplasm; ehrlichiosis has ____ (monocytes/granulocytes) with morulae.

A

Granulocytes; monocytes

322
Q

Q fever is caused by what bacterium? How is it contracted?

A

Coxiella burnetii; transmitted by spores from tick feces and cattle placenta inhaled as aerosols

323
Q

What are sources of the pathogen that causes leprosy?

A

Armadillos and humans with lepromatous leprosy

324
Q

How is Pasteurella multocida transmitted?

A

Animal bite (cats, dogs)

325
Q

A man contracts Coxiella burnetii while visiting his sister on a farm. What does this cause and how does it present?

A

Coxiella burnetii causes Q fever and presents as pneumonia

326
Q

A patient develops cellulitis and osteomyelitis around the site of a dog bite. What is the likely pathogen?

A

Pasteurella multocida

327
Q

What differentiates Q fever from the diseases of the Rickettsia genus, to which it is closely related? What is the pathogen?

A

Coxiella burnetii is the pathogen; it can survive outside in its endospore form, and there is no rash or vector

328
Q

What disease does Rickettsia prowazekii cause and what is its vector?

A

Epidemic typhus; lice

329
Q

A camper from North Carolina presents with fever and rash around the wrists and ankles. What is the treatment?

A

Doxycycline

330
Q

What is the vector for the pathogen that causes Rocky Mountain spotted fever?

A

Dermacentor tick bite transmits Rickettsia rickettsii, which causes Rocky Mountain spotted fever

331
Q

How is endemic typhus transmitted?

A

Fleas are the vectors for Rickettsia typhi

332
Q

What harbors the pathogen that causes the plague?

A

Fleas (rats and prairie dogs as reservoirs) harbor Yersinia pestis

333
Q

A patient contracts bubonic plague after being bitten by a flea containing what bacterium?

A

Yersinia pestis

334
Q

Name five gram-positive rods. Which one of the five is anaerobic?

A

Clostridium, Listeria, Bacillus, Mycobacterium, and Corynebacterium; Clostridium is anaerobic

335
Q

____ is an aerobic, gram-positive, acid-fast branching filament; ____ is anaerobic and not acid-fast stainable.

A

Nocardia; Actinomyces

336
Q

You culture a sputum sample, suspecting either Staphylococcus or Streptococcus. With which two methods can you differentiate the bacteria?

A

Both are gram-positive cocci, but staph is catalase positive and strep is catalase negative; strep grows in chains and staph in clusters

337
Q

You culture a cellulitis sample suspecting a Staphylococcus species. How can you differentiate among the three main species?

A

S. aureus is coagulase positive; of the coagulase-negative species, S. epidermidis is novobiocin sensitive and S. saprophyticus is resistant

338
Q

Chest x-ray of a 70-year-old man with a cough shows left lower lobe pneumonia. What hemolysis pattern does the most likely pathogen exhibit?

A

Streptococcus pneumoniae is the most common cause of pneumonia; it exhibits green partial (α-) hemolysis

339
Q

Some α-hemolytic cocci are bile soluble. Name the bug. What is the bile doing to the organism? Are any α-hemolytic bugs not bile soluble?

A

The bug is S. pneumoniae; the bile is lysing the bacteria; viridans streptococci (also α-hemolytic) are not lysed by bile

340
Q

A Streptococcus culture exhibits α-hemolysis. How will you further determine the species?

A

S. pneumoniae and S. viridans are α-hemolytic, but only S. pneumoniae has a capsule and is optochin sensitive

341
Q

A Streptococcus culture exhibits complete hemolysis. How will you further determine the species?

A

Both S. pyogenes and S. agalactiae are β-hemolytic—S. pyogenes is bacitracin sensitive and S. agalactiae is resistant

342
Q

Name two streptococci that are γ-hemolytic.

A

Enterococcus and non-Enterococcus species (e.g., Streptococcus bovis)

343
Q

Your culture of gram-positive, catalase-negative cocci exhibits no hemolysis. How will you further determine the species?

A

Nonenterococci species (e.g., Streptococcus bovis) will grow in bile but not in 6.5% NaCl; enterococci are the opposite

344
Q

On agar, partial (green) hemolysis is ___-hemolysis, complete (clear) hemolysis is ___-hemolysis, and absent hemolysis is ___-hemolysis.

A

α; β; γ

microbiology (2 decks)

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