Fastidious, GramNeg Rods: Haemophilus, Bordtetella, Legionella Flashcards
What is the gram stain for fastidious gram-neg rods? What does fastidious mean?
gram neg coccobacilli (very small). require special nurtirent/atmopshere/temperature conditions during specimen transport and growth
What are the three species of gram-neg rods?
Haemophilus sp, Bordetella sp., Legionella sp
Describe H. influenza…
it is normal flora of the respiratory tract, and it is found in encapsulated strains.
What strain of influenza causes most human disease?
B, and they can be systemic and life threatening
What is H. influenzas clinical signifigance?
respiratory tract infections (often secondary to viral infections)
Meningitis (dramatic, Hib vaccine)
Otitis Media
Conjunctivitis
What is H. flu’s virulence factor?
Capsule, it is antiphagocytic
How can you prevent H. influenzae?
Hib vaccine.
Hib treatment:
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
How do you grow H. flu?
on choco agar, and growth will occur in 24-48 hours.
Describe susceptibility testing for H. flu
non-life threatening disease: provide beta-lactamase test result. if pos= amp/amox
life threatening disease: provide full susceptibility results
Describe the general info of Bordetella pertussis
- It is the etiologic agent of pertussis.
- only human to human person, and children <1 are at risk for severe disease
- infection takes place with aerosals are inhaled
- bacteria attach and proliferate on ciliated epithelial cells
Describe the presenting disease of pertussis:
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!)
How do you detect the presence of B. pertussis?
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.
Do you have to specifically order a B. pertussis culture?
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.
What is the specimen choice for all tests?
Nasopharyngeal swab. ciliated ephitheal cells need to collected.