Haemophilus, Legionella, Bordetella Flashcards
For the Haemophilus spp, ___ is an important childhood pathogen and ___ causes genital ulcers (aka chancroid)
For the Haemophilus spp, H. influenzae is an important childhood pathogen and H. ducreyi causes genital ulcers (aka chancroid) (Ducreyi is the dude that’ll give you genital ulcers)
Haemophilus can be described as small, non-motile, Gram __ __ (shape)
T/F: Haemophilus has no capsule
Small, non-motile, Gram negative coccobacilli (short rods)
Falsehood. Some strains are encapsulated with a polysaccharide capsule. Most common antigenic type is Hib (type B)
What type of agar does Haemophilus grow on? (hint: it requires blood factors)
T/F: Haemophilus is a facultative anaerobe
Chocolate agar (requires factors: hemin (X factor) and NAD (V factor) )
True
H flu mainly infects the mucosa. ___ (encapsulated/un-encapsulated) strains are responsible for mucosal infections (respiratory disease, otitis media etc), whereas the (encapsulated/un-encapsulated) strains are responsible for systemic disease
H flu mainly infects the mucosa. Un-encapsulated strains are responsible for mucosal infections (respiratory disease, otitis media etc), whereas the encapsulated strains are responsible for systemic disease
*note that H flu doesn’t actually cause the flu*
The unencapsulated strains of H flu cause otitis media, __, __ and invasive infections
The unencapsulated strains of H flu cause otitis media, sinusitis, resp infections (pneumonia, bronchitis, COPD) and invasive infections
The encapsulated form of H flu is responsbile for more systemic infections, namely meningitis, ___, ___ and arthritis
The encapsulated form of H flu is responsbile for more systemic infections, namely meningitis (think about the kid with the space helmet), epiglottitis (remember the red cherries), conjunctivitis, otitis media (remember the kid blcking his ears coz the other kid is screaming), and arthritis
**HaEMOPhilus causes Epiglottitis - Epiglottitis, Meningitis, Otitis media and Pneumonia**
The virulence factors of H flu include the ___ present in Hib that is antiphagocytic, adherence factors, ___ (cousin of LPS), and the formation of a ___
Polysaccharide capsule (made up of PRP - antibodies to this are protective)
Adhesion factors (pili, etc)
Lipo-oligo-saccharide (LOS, modified LPS by addition of terminal **sialic acid >> evasion of immune responses)
Biofilm formation (promoted by LOS sialylation; possible contributor to CF (cystic fibrosis) pathogenesis)
**Note that sialic acid is common on the host cells as well so this is an example of molecular mimicry**
Dx of H flu includes a standard chocolate agar culture and a ___ test (hint: for the Hib capsule)
Culture (from sterile site – blood or CSF) on chocolate agar - (requires X and V factors)
Latex particle agglutination test (for Hib capsule)
Treatment of H flu infection includes:
___ +/- clavulanate for mucosal infections/resistant strains
Ceftriaxone for __
___ prophylaxis for close contacts
Treatment of H flu infection includes:
Amoxicillin +/- clavulanate for mucosal infections/resistant strains
Ceftriaxone for meningitis
Rifampin prophylaxis for close contacts
___ spp are pretty closely related to Haemophillus and cause similar diseases (rarely systemic tho)
Moraxella
Describe the morphology and Gram characteritics of Moraxella
Gram negative coccobacilli
What infections are caused by Moraxella and how do you treat Moraxella infection?
Otitis media, sinusitis, pneumonia, conjunctivitis (rarely systemic)
Treat with amoxicillin/clavulanate, cephalosporins
**when you hear Moraxella, just think the same as H flu in terms of pathogenesis and treatment**
Legionella pneumophila (major pathogen) is a gram __ bug with varying shape in lab media vs tissues (___ in media and coccobacilli in tissues)
long thin bacilli on lab media
short coccobacilli in tissues
Gram negative (note that its gram negative but since it stains poorly, you have to visualize on a silver stain)
Legionella is typically spread by ___ as it is present in natural water sources
Aerosols
2 diseases are caused by Legionella, namely ___ and ___
Legionnaires disease and Pontiac fever (remember the old pontiac looking vehicle coughing up smoke in the Sketchy vid)
Legionnaires disease is characterized by severe___, fever, ___cough (productive/non-productive), headaches/confusion
severe pneumonia
fever, non-productive cough, chills and headache, multi-organ involvement possible
• cerebellar involvement in several cases
___ is a less serious disease caused by Legionella and is characterized by ___ symtpoms.
T/F: This disease is generally self limiting
Pontiac fever is a less serious disease caused by Legionella and is characterized by flu-like symtpoms.
Truth. This disease is generally self limiting and doesn’t require antibiotics
Legionella typically infects alveolar macrophages and it does this by attaching via __ and forming a vacuole within the macrophage
Legionella typically infects alveolar macrophages and it does this by attaching via pili and forming a vacuole within the macrophage
Formation of a vacuole inside the legionella-infected macrophages helps inhibit ___. The bug then takes over the hosts ___ machinery for its growth, which is mediated by a ___ secretion system
Formation of a vacuole inside the legionella-infected macrophages helps inhibit early phagosome acidification and phagolysosome fusion. The bug then takes over the hosts ribosomal machinery for its growth, which is mediated by a Type IV secretion system
Inside the macrophage, Legionella bacteria continue to multiply. How do the bacteria become a virulent form and how does infection spread from cell to cell?
Depleted amino acid supply converts bacteria to virulent form
Infection spreads via lysis of vacuole and spent cell, spread to new cells
How do you Dx Legionella infection? ( 3 ways)
- Culture: difficult due to poor gram stain (remember you need to silver stain to see this bug)
culture on BCYE medium
- Urine antigen test (detects LPS)
- only detects serogroup 1 strains - Direct fluorescent Ab test from sputum
**Note that BCYE = buffered charcoal yeast extract in the presence of iron and cysteine**
Why wouldn’t you use a beta-lactam to treat Legionella infecion?
Which drugs would you use to treat Legionella pneumonia (hint: drug that coves atypicals)?
Which drugs are the drugs of choice if the dx is legionella infection?
Legionella produce b-lactamases (so beta lactams wouldn’t work)
Macrolides and fluoroquinolones
Lexofloxacin or Azithromycin
___ is a gram negative obligate intracellular bacillus most closely related to Legionella. Infection with this bug is mostly seen in vets, farmers and ranchers as the bug’s resevoirs are cattle, sheep and goats
Coxiella burnetii
Infection with Coxiella burnetti causes ___ in humans (self-limiting flu-like illness)
How would Dx and Rx infection with Coxiella?
Q_fever
Dx: serological
Rx: Doxycycline
___ is a human pathogen that causes whooping cough
Bordetella pertussis
Other bugs in the Bordetella family include ___, which causes a milder form of whooping cough, and ___, which is primarily an animal pathogen but can also infect immunocompromised humans
Other bugs in the Bordetella family include B. parapertussis, which causes a milder form of whooping cough, and B. bronchiseptica, which is primarily an animal pathogen but can also infect immunocompromised humans
Describe the morphology and gram staining of Bordetella
T/F: this bug has a polysaccharide capsule
Aerobic (slow growing) gram -ve coccobacilli
Falsehood. It don’t got no capsule
Bordetella pertussis is a highly contagious bug that is spread by __
Respiratory_Aerosols
The clinical presentation of pertussis consists of 3 stages:
___, which is characterized by non-specific symptoms, low grade fever
Paroxysmal phase, which is the stage during which ___ develops
___ phase, which is characterized by a gradual reduction in symptoms
Catarrhal phase, which is characterized by non-specific symptoms, low grade fever (1-2 wks)
Paroxysmal phase, which is the stage during which whooPing cough develops (2 wks to 2 months)
Convalescent phase, which is characterized by a gradual reduction in symptoms (a month plus)
Pertussis develops from bacteria in respiratory aerosols adhering to ___
Upon attachment, the bacteria don’t actually spread but instead release ___ that are responsible for symptoms
Pertussis develops from bacteria in respiratory aerosols adhering to ciliated respiratory epithelium
Upon attachment, the bacteria don’t actually spread but instead release exotoxins that are responsible for symptoms
The virulence factors of B pertussis include __ toxin, tracheal toxin and ___ toxin
Pertussis toxin
Adenylate Cyclase toxin
Tracheal toxin
Describe how Pertussis toxin causes disease
Pertussis toxin ribosylates Gi (inhibitory G proteins) and inactivates them >> increased cAMP and disables chemokine receptors for lymphocytes >> leukocytosis (WBCs can’tget into tissues) and respiratory symptoms
Dx of pertussis include culture on a ___ plate, PCR and serology
Dx of pertussis include culture on a Bordet-Gengou/Regan-Lowe plate, PCR and serology
Treatment of pertussis includes giving a ___ to prevent further spread, or ___ in case of an allergy.
Macrolide (Azithromycin) or TMP/SMX in case of allergy
**note also that there’s supportive therapy, and the acellular pertussis vaccine**
The 1st generation pertussis vaccines consisted of ___ and are no longer used
Current vaccines contain ___ and are much less reactogenic
The 1st generation pertussis vaccines consisted of heat/formalin killed whole cells and are no longer used (due to side effects and waning immunity by adulthood)
Current vaccines contain purified (detoxified) antigens, including PTX, and are much less reactogenic
