Haemophilus - Legionella

Question 1

This is a Gram (-) rod that is ID’d by small rods in CSF. It grows on chocolate agar but not blood agar and requires X and V growth factors on trypstose agar.

Answer 1

Haemophilus influenzae

Question 2

What is the satellite phenomenon of H. flu?

Answer 2

grows on blood agar around Staph. aureus

Question 3

H. flu causes meningitis mostly in un-immunized kids. How does it progress?

Answer 3

initially a mild URI then progresses to fever and systemic signs

Question 4

H. flu causes Epiglottitis and may lead to complete airway blockage. How do patients present?

Answer 4

appear sick, restless, pale or cyanotic, tachycardic

Question 5

Conjunctivitis can result from what type of strains of H. flu?

Answer 5

un-encapsulated

Question 6

H. flu causes Brazilian Purpuric fever. Describe its progression and symptoms.

Answer 6

caused by aegyptius biogroup; initial conjunctivitis, then fever, vomiting and abdominal pain after a few days, then with no treatment it progresses to petechiae, purpura, shock and death

Question 7

What are the virulence factors of H. flu?

Answer 7

virulent strains are capsulated; pili

Question 8

This is a Gram (-) rod with parallel chain rice grain morphology. It is ID’d by gram stain of swab of lesion. It requires factor X for growth.

Answer 8

Haemophilus ducreyi

Question 9

How does one contract H. ducreyi?

Answer 9

STD; individuals are more susceptible when dehydrated

Question 10

H. ducreyi causes what disease? remember, it’s an STD

Answer 10

Chancroid - genital ulcers and inguinal adenitis

Question 11

Describe the progression of Chancroid

Answer 11

4-7 d post exposure a papule develops with surrounding edema, then 2-3 d later it develops into a pustule that will rupture and evolve into a painful ulcer

Question 12

This species of bacteria includes H. parainfluenzae, Actinobacillus, Cardiobacterium, Eikenella, and Kingella. They are Gram (-) rods that grow slowly on blood agar.

Answer 12

HACEK species

Question 13

H. parainfluenzae requires ___ factor only

Answer 13

V

Question 14

Where is the HACEK species found and where do individuals commonly get infected by it?

Answer 14

found in normal flora of URT and oral cavity; daycare setting

Question 15

What diseases do HACEK species cause?

Answer 15

Endocarditis, Septic Arthritis, Bite wounds, Peridontal disease

Question 16

This is a G(-) coccobacilli. It is ID’d on Regan-lowe charcoal agar or Bordet-gengou charcoal agar. It’s oxidase positive and doesn’t grow on MA

Answer 16

Bordatella pertussis

Question 17

Bordatella pertussis causes whooping cough. Describe the progression of this disease.

Answer 17

catarrhal stage: after 7-10 d initial cold symptoms that last 1-2 weeks, most contagious during this stage

Paroxysmal phase: cough becomes frequent and spasmodic with repetitive bursts of 5-10 coughs, vomiting after coughing spell is common

Convalescent stage: coughs are less frequent and severe, may last 1-3 months and they may get neurological events like seizures and encephalopathy

Question 18

In regards to virulence factors, Bordatella pertussis produces pertussis toxin. What does it do?

Answer 18

acts as adhesin and toxin; it causes ADP-ribosylation of a G protein that leads to more cAMP and inhibits phagocytic killing and monocyte migration

Question 19

This is a Gram (-) pleomorphic rod. ID’d by culture on buffered charcoal yeast extract agar, immunofluorescence and pcr. It Gram stains poorly.

Answer 19

Legionella

Question 20

What are clinical clues for Legionaire’s disease?

Answer 20

high fever, diarrhea, high PMNs but no organism in gram stain of samples, hyponatremia

Question 21

L. peumophila causes most of the Legionella infections. It is an ____ ____ and signifcant cause of community ____

Answer 21

aquatic saporphyte (lakes, shower heads, AC’s); pneumonia

Question 22

This disease caused by Legionella can be described as acute, self-limited, flu-like; malaise, fever, fatigue, and myalgia but pneumonia doesn’t develop

Answer 22

Pontiac Fever

Question 23

_____ disease (pneumonia) is usually atypical (non productive cough, non purulent sputum) but more severe than other atypical pneumonia. There is a mild cough and fever - widespread infiltration and multi-organ failure, GI symptoms, systemic signs (fever, dyspnea, DELERIUM, rigors)

Answer 23

Legionnaire’s

Question 24

In regards to virulence, outer membrane proteins help Legionella bind to ____ macrophages and once endocytosed, they prevent ____ ____ fusion by blocking acidification. They then replicate until the cell ruptures.

Answer 24

alveolar; phagosome lysosome