Haemophilus, Legionella, Bordetella

Question 1

For the Haemophilus spp, ___ is an important childhood pathogen and ___ causes genital ulcers (aka chancroid)

Answer 1

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)

Question 2

Haemophilus can be described as small, non-motile, Gram __ __ (shape)

T/F: Haemophilus has no capsule

Answer 2

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)

Question 3

What type of agar does Haemophilus grow on? (hint: it requires blood factors)

T/F: Haemophilus is a facultative anaerobe

Answer 3

Chocolate agar (requires factors: hemin (X factor) and NAD (V factor) )

True

Question 4

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

Answer 4

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*

Question 5

The unencapsulated strains of H flu cause otitis media, __, __ and invasive infections

Answer 5

The unencapsulated strains of H flu cause otitis media, sinusitis, resp infections (pneumonia, bronchitis, COPD) and invasive infections

Question 6

The encapsulated form of H flu is responsbile for more systemic infections, namely meningitis, ___, ___ and arthritis

Answer 6

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**

Question 7

The virulence factors of H flu include the ___ present in Hib that is antiphagocytic, adherence factors, ___ (cousin of LPS), and the formation of a ___

Answer 7

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**

Question 8

Dx of H flu includes a standard chocolate agar culture and a ___ test (hint: for the Hib capsule)

Answer 8

Culture (from sterile site – blood or CSF) on chocolate agar - (requires X and V factors)

Latex particle agglutination test (for Hib capsule)

Question 9

Treatment of H flu infection includes:

___ +/- clavulanate for mucosal infections/resistant strains

Ceftriaxone for __

___ prophylaxis for close contacts

Answer 9

Treatment of H flu infection includes:

Amoxicillin +/- clavulanate for mucosal infections/resistant strains

Ceftriaxone for meningitis

Rifampin prophylaxis for close contacts

Question 10

___ spp are pretty closely related to Haemophillus and cause similar diseases (rarely systemic tho)

Answer 10

Moraxella

Question 11

Describe the morphology and Gram characteritics of Moraxella

Answer 11

Gram negative coccobacilli

Question 12

What infections are caused by Moraxella and how do you treat Moraxella infection?

Answer 12

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**

Question 13

Legionella pneumophila (major pathogen) is a gram __ bug with varying shape in lab media vs tissues (___ in media and coccobacilli in tissues)

Answer 13

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)

Question 14

Legionella is typically spread by ___ as it is present in natural water sources

Answer 14

Aerosols

Question 15

2 diseases are caused by Legionella, namely ___ and ___

Answer 15

Legionnaires disease and Pontiac fever (remember the old pontiac looking vehicle coughing up smoke in the Sketchy vid)

Question 16

Legionnaires disease is characterized by severe___, fever, ___cough (productive/non-productive), headaches/confusion

Answer 16

severe pneumonia

fever, non-productive cough, chills and headache, multi-organ involvement possible

• cerebellar involvement in several cases

Question 17

___ is a less serious disease caused by Legionella and is characterized by ___ symtpoms.

T/F: This disease is generally self limiting

Answer 17

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

Question 18

Legionella typically infects alveolar macrophages and it does this by attaching via __ and forming a vacuole within the macrophage

Answer 18

Legionella typically infects alveolar macrophages and it does this by attaching via pili and forming a vacuole within the macrophage

Question 19

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

Answer 19

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

Question 20

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?

Answer 20

Depleted amino acid supply converts bacteria to virulent form

Infection spreads via lysis of vacuole and spent cell, spread to new cells

Question 21

How do you Dx Legionella infection? ( 3 ways)

Answer 21

1. Culture: difficult due to poor gram stain (remember you need to silver stain to see this bug)

culture on BCYE medium

2. Urine antigen test (detects LPS)
   - only detects serogroup 1 strains
3. Direct fluorescent Ab test from sputum

**Note that BCYE = buffered charcoal yeast extract in the presence of iron and cysteine**

Question 22

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?

Answer 22

Legionella produce b-lactamases (so beta lactams wouldn’t work)

Macrolides and fluoroquinolones

Lexofloxacin or Azithromycin

Question 23

___ 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

Answer 23

Coxiella burnetii

Question 24

Infection with Coxiella burnetti causes ___ in humans (self-limiting flu-like illness)

How would Dx and Rx infection with Coxiella?

Answer 24

Q_fever

Dx: serological

Rx: Doxycycline

Question 25

___ is a human pathogen that causes whooping cough

Answer 25

Bordetella pertussis

Question 26

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

Answer 26

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

Question 27

Describe the morphology and gram staining of Bordetella

T/F: this bug has a polysaccharide capsule

Answer 27

Aerobic (slow growing) gram -ve coccobacilli

Falsehood. It don’t got no capsule

Question 28

Bordetella pertussis is a highly contagious bug that is spread by __

Answer 28

Respiratory_Aerosols

Question 29

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

Answer 29

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)

Question 30

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

Answer 30

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

Question 31

The virulence factors of B pertussis include __ toxin, tracheal toxin and ___ toxin

Answer 31

Pertussis toxin

Adenylate Cyclase toxin

Tracheal toxin

Question 32

Describe how Pertussis toxin causes disease

Answer 32

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

Question 33

Dx of pertussis include culture on a ___ plate, PCR and serology

Answer 33

Dx of pertussis include culture on a Bordet-Gengou/Regan-Lowe plate, PCR and serology

Question 34

Treatment of pertussis includes giving a ___ to prevent further spread, or ___ in case of an allergy.

Answer 34

Macrolide (Azithromycin) or TMP/SMX in case of allergy

**note also that there’s supportive therapy, and the acellular pertussis vaccine**

Question 35

The 1st generation pertussis vaccines consisted of ___ and are no longer used

Current vaccines contain ___ and are much less reactogenic

Answer 35

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