Exam 2 Lecture 14 Flashcards
Clinically important Haemophilus species:
- H. influenzae
2. H. ducreyi
Haemophilus Gram Stain
Gram negative, thin, coccobacilli/short rods
Why do we care about H. influenzae diseases?
we have a safe vaccine, but there are still hundreds to thousands of cases of severe disease/deaths
True or false: On the evolutionary tree shown in lecture, there are a bunch of “H. flu”s grouped together, so they are evolutionarily very related to one another.
True
True or false: H. ducreyi is slightly different than H. flu both clinically and genetically.
True
H. flu grows on what media? What do the colonies look like on media?
Chocolate agar; flat/convex
Haemophilus spp are ____ ____, so they can grow both aerobically and anaerobically.
facultative anaerobes
Both H. flu and H. ducreyi like to grow with ___ supplementation
5% CO2
H. flu likes to grow at __-__ ºC
35-37 (right around body temp)
H. ducreyi likes to grow at __-__ ºC
33-35
True or false: clinically, we usually are not able to grow H. flu on media, but we can more easily grow H. ducreyi
False: clinically we usually cannot grow H. ducreyi
Haemophilus spp are __-___ and do not form ____.
non-motile; spores
Haemophilus spp are _____ and require these two factors in order to be cultivated:
fastidious; Protoporphyrin IX (X factor) and NAD (V factor)
What does Haemophilus ferment?
Glucose
Haemophilus cannot ferment ____. Therefore, it will grow on ____ ___ but won’t turn pink.
lactate; MacConkey agar
How can X factor and V factor be acquired?
by lysing erythrocytes (thus why H. influenzae is grown on chocolate agar)
Haemophilus spp are ____ and ____-positive.
catalase and oxidase
Haemophilus spp can reduce ____ to ____
nitrate to nitrite
Which Haemophilus species may grow on blood agar?
H. haemolyticus
True or false: H. influenzae must be encapsulated in order to be pathogenic.
False. Can be encapsulated (serotypes a through f) or not (NTHI)
Which H. influenzae serotype have we created a vaccine against?
Type B (Hib)
H. influenzae Type B _____ capsule is comprised of ___, which is strongly associated with ____.
polysaccharide; PRP (polyribitol phosphate); virulence
What are some characteristics of NTHI? (3)
- non-encapsulated
- typically colonizes the nasopharynx
- majority of diseases now caused by NTHI
Why is majority of disease now NTHI?
Increase in vaccinations against Hib creates a hole in the population, which is filled by NTHI
2 important things to know about Type B capsule
- leads to immune escape (anti-phagocytic)
2. is a component of the vaccine
Describe the epidemiology of H. influenza incidences before vaccination
mainly young children of school age were affected, especially 4 y.o.
What are 2 main severe diseases that can arise from H. influenzae infection?
- Meningitis (50%)
2. Epiglottits (17%)
What happened to disease incidences once the Hib vaccine was introduced?
Drastically changed the epidemiology - as we started to vaccinate, number of incidences drastically reduced to almost 0
What are the consequences of Hib vaccinations? (hint: think about relationship between Hib and NTHI)
shift in epidemiology - as Hib decreased, NTHI increased, meaning that more H. flu infections are caused by NTHI compared to before vaccination
Once H. influenzae enters the ____, the organism can disseminate into the ear canal and can cause ___ ___ ____.
nasopharynx; acute otitis media
What are some symptoms of AOM?
bulging tympanic membrane, redness, swelling, pus
ABM stands for:
acute bacterial meningitis
H. influenza can also infect the eye, causing _____.
conjunctivitis
Why is epiglottitis so life threatening?
The swelling that results from the infection can be a point of potential constriction in the proximal airway. It can also be difficult to get a breathing tube through.
True or false: H. influenzae can also cause lower respiratory tract infections, such as pneumonia.
True
There are __ patient populations of H. flu-induced pneumonia, which include:
2;
- Kids 4 months - 4 years old
- Older adults with bronchociliary dysfunction (can’t clear mucus/bacteria)
Besides the Type B capsule, what other virulence factors does H. influenzae have?
Adhesins such as Protein E, OMP2, Type IV Pilus
Which antibiotics can be used to treat H. influenzae infection?
Amoxicillin (aminopenicillin) or Amox-Clavulonate (w/ beta-lactamase inhibitor)
True or false: H. influenzae has a lot of antibiotic resistance
False: there is some antibiotic resistance, but generally narrow beta-lactamase resistance
True or false: If the H. flu infection is serious, we can use IV antibiotics such as vancomycin.
False: we can use IV, but use ceftriaxone, cefotax, amp-sulbactam
H. aegyptius causes:
conjunctivitis
H. parainfluenzae causes:
AOM, sinusitis (also H. influenzae)
H. haemolyticus causes:
invasive disease
Sequencing distinguishes H. haemolyticus from ______
H. influenzae
H. ducreyi causes disease that is clinically similar to____
syphilis
True or false: H. ducreyi is not a prevalent pathogen in the U.S.
True (roughly dozen cases/year)
How does chancroid present?
multiple ulcerated lesions, adenopathy, pain at the site of the ulcerated lesion, gray/yellow exudate
Which of these symptoms is a key clue that distinguishes chancroid vs primary syphilis?
A. ulcerated lesion appearance
B. pain
C. neither
pain
H. ducreyi can __-____ with other STIs and it is treated empirically with ____.
co-occur; Beta lactams
True or false: once you have been infected with H. ducreyi, you will have life-long immunity.
False
Bordetella Gram Stain
gram negative, coccobacilli/short rods
___-___ is a common media used to cultivate Bordetella, and colonies usually show up as:
Regan-Lowe; small, shiny/silvery, round, domed
When growing Bordetella in ___-___ media, there is slight hemolysis.
Bordet-Gengou
True or false: Bordetella is is a facultative aerobe.
False: strict aerobe
True or false: Bordetella is not encapsulated nor forms spores
True
Bordetella is ____ positive.
Oxidase
True or false: B. bronchiseptica is motile
true
B. parapertussis has ___ ____
brown pigment
True or false: B. bronchiseptica and rare Bordetella spp can grow on MacConkeys
True
The reservoir of B. pertussis is ___, ____, and __ ____. Do these people usually get whooping cough?
adults; adolescents; older children; no, but can get chronic cough
Where do we commonly see B. pertussis disease?
unimmunized patients, young babies (< 6 months), no immune system
Clinical pertussis is characterized by: (4)
- prolonged cough
- distinct whoop
- CFU #’s decrease over time
- lymphocytosis
Those with clinical pertussis are most infectious at:
and most non-infectious at:
~ 3 weeks; ~4-5 weeks
B. pertussis produces ____ ____, which can stick to ciliated airways, but not ____.
filamentous hemagglutin; alveoli
Catarrhal phase
bacterial load is high; cough may start; infectious but not sure if it’s whooping cough at this stage
Intensity of whooping cough peaks at around:
2-3 weeks
B. pertussis produces toxins such as:
- Adenylate Cyclase Toxin
- Pertussis toxin
- Tracheal cytotoxin
Important virulence/adherence factors for B. pertussis
FHA, Toxins, Fimbriae
FHA structure/function
big, long structure that allows relatively close contact with epithelium
Pertussis toxin contains __ and __ subunit, similar to DT toxin. Intake of Pertussis toxin leads to:
A; B; shuts down immune cell response
Adenylate cyclase toxin function
impairs macrophage function by suppressing nitric oxide production
Pertussis treatment
Macrolides (erythromycin for babies); intubation/ventilation for respiratory distress
