Fastidious, GramNeg Rods: Haemophilus, Bordtetella, Legionella Flashcards

1
Q

What is the gram stain for fastidious gram-neg rods? What does fastidious mean?

A

gram neg coccobacilli (very small). require special nurtirent/atmopshere/temperature conditions during specimen transport and growth

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2
Q

What are the three species of gram-neg rods?

A

Haemophilus sp, Bordetella sp., Legionella sp

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3
Q

Describe H. influenza…

A

it is normal flora of the respiratory tract, and it is found in encapsulated strains.

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4
Q

What strain of influenza causes most human disease?

A

B, and they can be systemic and life threatening

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5
Q

What is H. influenzas clinical signifigance?

A

respiratory tract infections (often secondary to viral infections)
Meningitis (dramatic, Hib vaccine)
Otitis Media
Conjunctivitis

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6
Q

What is H. flu’s virulence factor?

A

Capsule, it is antiphagocytic

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7
Q

How can you prevent H. influenzae?

A

Hib vaccine.

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8
Q

Hib treatment:

A
life threatening disease (meningitis): 
1. cefotaxime or ceftriaxone. 
2. alt: amp, beta-lacatamse neg, and FQ
non-life threatening disease:
1. augmentin, oral second or third generation cephalosporins
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9
Q

How do you grow H. flu?

A

on choco agar, and growth will occur in 24-48 hours.

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10
Q

Describe susceptibility testing for H. flu

A

non-life threatening disease: provide beta-lactamase test result. if pos= amp/amox

life threatening disease: provide full susceptibility results

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11
Q

Describe the general info of Bordetella pertussis

A
  1. It is the etiologic agent of pertussis.
  2. only human to human person, and children <1 are at risk for severe disease
  3. infection takes place with aerosals are inhaled
  4. bacteria attach and proliferate on ciliated epithelial cells
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12
Q

Describe the presenting disease of pertussis:

A

incubation: 7-10 days
Catarhal stage: 1-2 weeks, common cold
Paraxysmal state: reptitive cough, inspiratory whoops, and vomitting
Convalesccence: 3-4 weeks (but in med class it says it can be up to 12!)

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13
Q

How do you detect the presence of B. pertussis?

A

direct specimen detection (nucleic acid testing–no FDA approved method), results within 2-24 hours. Organism does not need to remain viable to accurate test results.

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14
Q

Do you have to specifically order a B. pertussis culture?

A

Yes, plate the specimen at the bedside. Submit immediately. Specimen must be cultured within 24 hours of collection. FOR CULTURE–organism must be viable. held 7 days.

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15
Q

What is the specimen choice for all tests?

A

Nasopharyngeal swab. ciliated ephitheal cells need to collected.

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16
Q

What is the treatment for B. pertussis?

A

marcolides or SXT. Prevent with dtap vaccine.

17
Q

Describe the basics of legionella sp.

A

Pontiac fever : self limited, flu like
Pneumonia: Severe

you AQUIRE this from the inhalation of organism from water source. NOT person to person.
you get legion from a region with contaminated water

18
Q

Who is at risk for legionnaire’s disease?

A

> 40 years old, compromised pulmonary function, decreased cellular immunity, nosocmial pathogen.

19
Q

Describe the presentation of Legionnaires disease?

A

after 2-10 days of incubation: fever, chills with pneumonia. Nonproductive, dry cough, multiorgan disease.

20
Q

Legionnaires disease prevention:

A

ID of environmental source, hyperchlorinate the water, maintenence of elevated water temps, immunosuppressed patients need their water pipes flushed out.

21
Q

What is the specimen of choice Legionella?

A

bronchial aveolar lavage. Direct fluroescent antibody, nucleic acid detection, urine antigen detection (only 1 antigen)

22
Q

Culture of legionella

A

MUST be SPECIFICALLY ORDERED. BAL will be inoculated into buffered charcoal yeast extract agar. Growth usually occurs in 3-5 days.

23
Q

Susceptibility testing for legionelle:

A

no methods available due to fastidious nature of organism. Drugs of choice: FQ, macrolides.