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Owenbacteria Block 2 > Respiratory Pathogens > Flashcards

Respiratory Pathogens Flashcards

1
Q

What is the motility, spore formation, oxygen use, and shape of Mycobacterium?

A
  1. Non-motile
  2. Non-spore forming
  3. Aerobic
  4. Rods
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2
Q

What makes Mycobacterium resistant to disinfectants and common stains?

A

It’s lipid-rich cell wall

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3
Q
  1. What type of staining is used to identify Mycobacterium?
  2. Why is Mycobacterium hard to identify via culture?
A
  1. Acid-fast staining (Not really Gram-positive)
  2. It is very slow growing (3-4 weeks)
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4
Q
  1. What two pathogens of the M. tuberculosis complex infect humans?
  2. What other two Mycobacterium cause disease in humans?
A
  1. M. tuberculosis, and M. africanum
  2. M. leprae (Leprosy), M. avium complex (MAC)
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5
Q

There are two specific MAC bacteria: M. avium and M. intracellulare. Which bug infects which type of patient?

A
  • M. avium* - HIV patients
  • M. intracellulare* - Immunocompromised
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6
Q
  1. What is a defining structural characteristic of M. tuberculosis?
  2. How does this contribute to it’s virulence?
  3. How is this used in screening?
A
  1. It’s complex lipid cell wall (60% of dry weight).
  2. It makes it resistant to antimicrobials, Cord factor participates in production of caseating granulomas
  3. It is an important modulator in immune response used in PPD skin test.
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7
Q
  1. What are the reservoirs for M. tuberculosis?
  2. How many people are infected with TB worldwide?
  3. What is prominent about TB epidemiology in HIV patients?
  4. What is needed for transmission?
A
  1. Humans are the only reservoir
  2. ~2 billion - 1 in 3 people
  3. It is the leading cause of death in HIV patients
  4. Close contact for extended periods of time
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8
Q
  1. What type of transmission/precaution is necessary for M. tuberculosis?
  2. How long is the typical initial bacterial replication phase?
  3. What is the risk of active infection after exposure?
A
  1. Inhalation of droplet transmission
  2. 3-6 weeks
  3. 5% in 1-2 years, 10% lifetime, 10% annually for immunocompromised
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9
Q
  1. Are people with latent infections contagious?
  2. What imaging indicates active disease?
  3. What symptoms are present in active TB?
A
  1. No, only active infections are transmitable
  2. Dense lesions on x-ray
  3. Malaise, weight loss, productive cough, night sweats.
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10
Q
  1. Describe Granulomas.
A
  1. Areas of activated immune cells that arrest infectious bacteria. Future immune insult can result in “reactivation disease.”
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11
Q
  1. Suppression of what cytokines and cellular enzymes result in increased risk for reactivation?
  2. What is the risk of reactivation in healthy vs. immune compromised patients?
A
  1. TNF-alpha, INF-gamma, iNOS
  2. 10% lifetime vs. 10% annually
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12
Q
  1. What is the result of a PPD test for active disease vs. latent disease?
  2. What is the difference in CXR and sputum for active disease vs. latent disease?
  3. How contagious are people with active vs. latent disease?
A
  1. Both are positive
  2. Abnormal CXR and sputum for active disease. Normal for latent disease.
  3. Active disease is highly infectious. Latent disease cannot be spread to others.
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13
Q
  1. What is the major drawback of the PPD test?
  2. What other two tests are quick diagnostic tools for TB?
  3. What is the gold standard for confirming TB? Why can this be problematic?
A
  1. PPD skin test doesn’t tell you which species of Mycobacterium you were exposed to.
  2. Quantiferon test detects INF-gamma. Sputum sample with microscopy.
  3. Culture is gold standard. May take 3-6 weeks.
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14
Q
  1. What is the PPD a mixture of?
  2. What is considered a positive result?
  3. How is active or latent infection determined? Can the PPD alone determine this?
A
  1. Tuberculoproteins from the cell wall.
  2. Induration of >10 mm using 5 TU of PPD is positive.
  3. CXR. No PPD alone is not good enough.
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15
Q
  1. What are the secreted antigens that are specific to TB that are used by the Quantiferon test?
A
  1. ESAT-6 and CFP-10
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16
Q

What type of stain for TB is the following image?

A

Carbol Fuschin

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17
Q

What type of TB stain is shown in the following image?

A

Ziehl-Neelson

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18
Q

What type of stain for TB is shown in the following image?

A

Auramine-Rhodamine

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19
Q

Why isn’t gram-stain effective for TB visualization?

A

It’s hydrophobic cell envelop (lots of long chain fatty acids = mycolic acids

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20
Q

What is the recomended course for acute TB infections?

What is the recommended treatment for latent TB? Why isn’t it entirely effective?

A

2 months of: Isoniazid, Rifampicin, Ethambutol, and Pyrazinamide

Followed by 4 months of: Isoniazid and Rifampicin

9 months of isoniazid. Doesn’t always sterilize b/c Isoniazid is most effective against replicating bacteria.

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21
Q

Why is adherence to TB regimen so critical?

A

Non-compliance can result in emergency of MDR or XDR strains.

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22
Q
  1. What does MDR resistance mean? What impact does this have on treatment?
  2. What does XDR mean? What impact does this have on treatment?
A
  1. Resistance to both Isoniazid and rifampicin. Requires multiple antibiotics for up to 2 years
  2. Resistance to most known antibiotics for TB. Prognosis is grim.
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23
Q
  1. What type of vaccine is the BCG vaccine? What does the BCG TB vaccine protect against? What does it not protect against?
A
  1. It is a live vaccine. It protects against over disease but not infection and has a varied protection rate.
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24
Q
  1. Where is *M. leprae *seen in the US? Why?
  2. How is Leprosy spread?
  3. M. leprae has had a substantial reduction in its genome with 50% no longer coding for proteins. What does this mean clinically?
A
  1. The south. It is endemic in armadillos.
  2. By person to person contact. Transmission by inhalation or direct contact with respiratory secretions
  3. It has limited metabolic capability and cannot be cultured on laboratory medium. Usually cultured in armadillos or nude mice.
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25
Q
  1. What are the two main types of leprosy?
A
  1. Tuberculoidal leprosy, Lepromatous leprosy
26
Q

What differentiates Tuberculoidal vs. Lepromatous leprosy immunologically?

A

Tuberculoidal has a strong cell-mediated immune response but weak humoral response. (Few bacilli present in tissues)

Lepromatous manifests following a strong humoral response, but weak cell mediated response. (Abundance of bacilli in macrophages)

27
Q

What are the hallmarks physical symptoms of Tuberculoidal leprosy? (3 points)

A

Extensive peripheral nerve damage and sensory loss

Enlargement of nerves

They are not infectious due to limited number of bacilli.

28
Q

What are the hallmark symptoms of Lepromatous leprosy? (3 points)

A

Many erythematous plaques resulting in extensive tissue destruction.

Little sensory loss is present.

Highly infections due to number of acid-fast bacilli in lesions.

29
Q

Which type of leprosy is depicted here?

A

Lepromatous

30
Q

What is the following an image of?

A

Tuberculoid leprosy

31
Q
  1. Where is Mycobacterium avium (MAC) commonly found?
  2. Who does it commonly infect?
  3. How is it commonly contracted?
A
  1. Environmental isolate of soil and water
  2. Individuals with HIV creating disseminated disease.
  3. Ingestion
32
Q
  1. What are the reservoirs for Micobacterium bovis?
  2. How is it typically contracted?
  3. What happens if organisms are inhaled?
A
  1. Cattle and Humans
  2. Unpasteurized milk or dairy products.
  3. Disease indistinguishable from M. tuberculosis
33
Q
  1. Who does Mycobacterium marinum infect and what is it frequently associated with?
  2. How is it commonly acquired?
  3. Where is this disease primarily seen?
A
  1. It is an opportunistic pathogen and is associated with skin lesions.
  2. Swimming pools and hot tubs.
  3. In fish and frogs.
34
Q
  1. What is the basic physical structure of Legionella**?
  2. What is Legionella’s relationship with oxygen? How does this affect where the infect?
  3. What type of people are susceptible to Legionella?
  4. How does Legionella appear on gram-stain? How is this overcome?
A
  1. **Gram-negative, **unencapsulated rod with single polar flagella
  2. Obligate aerobes that infect the lungs.
  3. Immunosuppressed. It is an opportunistic pathogen.
  4. They stain poorly and require fuschin rather than safarin.
35
Q
  1. What are the unique growth requirements of Legionella?
  2. How does Legionella derive most of it’s energy?
A
  1. They are complex and require **L-cysteine **and ferric iron.
  2. From breaking down amino acids rather than carbohydrates.
36
Q
  1. Legionella are the cause of what two common name diseases?
  2. What are the rates of new infection in the US?
  3. What percentage of people die after Legionella infection?
A
  1. Legionaire’s disease and Pontiac Fever
  2. 8-18,000/year
  3. 5-30%
37
Q
  1. What Legionella type is responsible for most human disease?
  2. How are individual species differentiated?
A
  1. L. pneumophila serogroup 1
  2. Outer membrane proteins and polysaccharide
38
Q
  1. What is the major non-human reservoir for Legionella?
  2. What accounts for Legionella’s incredible staying power?
A
  1. Water dwelling ameoba
  2. Legionella’s ability to form biofilms
39
Q
  1. Is Legionella also part of normal flora or is it only acquired?
  2. How do we contract Legionella from water?
  3. Can Legionella be transmitted person to person?
  4. Who is most affected by Legionella?
A
  1. They are not part of normal flora. They are typically acquired by inhalation.
  2. Drinking water alone is not enough, one must aspirate contaminated water.
  3. No person to person transmission reported
  4. Legionella are opportunistic pathogens. They primarily affect immunocompromised individuals.
40
Q
  1. Where does Legionella survive within humans?
  2. What does Legionella produce to aid in it’s survival?
  3. What type of secretion system do Legionella use?
  4. What does this system do?
A
  1. Within Macrophages
  2. Cytotoxins, hemolysins, proteases, endotoxins, and lipases
  3. Type IV secretion system
  4. Delivers virulence effectors directly into macrophages
41
Q

How does Legionella resist being killed by macrophage reactive oxygen intermediates?

A

It prevents phagosome-lysosome fusion

42
Q
  1. What are the clinical features of Legionaire’s disease?
  2. Is Legionaire’s visible by radiograph?
  3. What is the incubation period for Legionaire’s disease?
  4. What is the prognosis for Legionaire’s?
A
  1. Pneumonia, cough, fever, chest pain
  2. Yes
  3. 2-14 days
  4. Fatality common - 5%-40%
43
Q
  1. What are the clinical features of Pontiac Fever?
  2. Is Pontiac fever visible on radiograph?
  3. What is the incubation period for Pontiac Fever?
  4. What is the prognosis for Pontiac Fever?
A
  1. Flu-like Illness
  2. NO
  3. 24-48 hrs after exposure
  4. Hospitalization un-common. Fatality rate 0%
44
Q
  1. How can Legionella be identified by Microscopy?
  2. What culture medium is needed for Legionella?
  3. How long might it take to diagnose Legionella by serology?
A
  1. Using a differential fluorescent antibody
  2. **Specialized media - **Buffered charcoal yeast extract
  3. Up to 3 weeks for titers to be high enough
45
Q

What organism is pictured below? By what technique? On what medium?

A

Legionella, by DFA microscopy, on glass slide

46
Q

What organism is pictured below? By what technique? On what medium? Given what “hallmark appearance”?

A

Legionella, by culture, on Buffered charcoal yeast extract, giving a “cut glass” appearance

47
Q

How can infected water sources be cleared of Legionella?

A

Chlorine treatment or by superheating

48
Q
  1. What are the general physical characteristics of Pseudomonas?
  2. What type of pathogen are pseudomonas? Where can they be found?
  3. How are they commonly found to exist?
A
  1. Gram-negative rods with a polar flagella
  2. They are opportunists that are ubiquitous to water and soil.
  3. As biofilms and microcolonies on inanimate objects (plastic tubes)
49
Q

What does Pseudomonas use as an energy source?

A

They oxidize carbohydrates (oxidase-positive)

50
Q

Why is pseudomonas difficult to clear from surfaces?

A

It is highly resistant to chemical disinfection

51
Q

What is a Gram-negative rod with polar flagella, oxidase-positive, strongly hemolytic, and greenish in color and capable of growing in elevated temperatures?

A

Pseudomonas aeruginosa

52
Q

Where is P. aeruginosa commonly isolated in hospitals?

A

Sinks & toilets
Dialysis equipment
Catheters & Respiratory equipment

53
Q
  1. What two types of injuries are commonly infected because of P. aeruginosa’s ubiquity in nature?
  2. What type of chronic illness patient commonly dies from P. Aeruginosa?
A
  1. Burn patients and puncture wounds
  2. Cystic Fibrosis patients with a mucoid phenotype
54
Q
  1. What are common early life colonization bugs?
  2. What is a common late life colonization bug?
A
  1. S. aureus and H. influenzae
  2. P. aeruginosa
55
Q

What virulence factors are produced by P. aeruginosa and to what effect for each?

A

adhesins – promote binding
polysaccharide capsule alginate – mucoid phenotype
Endotoxin – septic shock
Pyocyanin and pyochelin pigments – release of ROS
Exotoxins – Extensive tissue damage
Proteases – host tissue damage

56
Q

Where does psuedomonas create it’s effect relative to host cells?

A

It remains outside the cell compared to Legionella which is an intracellular pathogen.

57
Q

What is the following image depicting? How is it obtained?

A

Pseudomonas corneal ulcer obtained by extended wear contacts.

58
Q
  1. What is the most effective way to positively ID P. aeruginosa?
A
  1. Culture
59
Q

What is another pseudomonad that causes respiratory infections in CF or CGD patients and what is it sensitive to?

A

Burkholderia cepacia which is sensitive to trimethoprim-sulfamethoxazole

60
Q

What is another pseudomonad that is a saphrophyte of soil and water and mainly responsible for opportunistic infections?

A

Burkholderia pseudomallei

Owenbacteria Block 2 (12 decks)

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