FASTIDIOUS GRAM NEGATIVE RODS.1

Question 1

What are fastidious bacterias

Answer 1

are microorganisms that have complex nutritional requirements and need specific conditions for their growth

Question 2

difference between fastidious and non-fastidious bacteria

Answer 2

Fastidious bacterias have complex nutritional requirements and need specific conditions for their growth while non-fastidios bacteria can grow on general media

Question 3

mention three medically important gram negative rods associated with respiratory tract

Answer 3

1. Haemophilus influezae
2. Bordetella pertussis
3. Legionella pneumophila

Question 4

mention zoonotic gram negative rods

Answer 4

Brucella species e.g Francisella tularensis, Yersinia pestis and pasteurella multocida

Question 5

mention the gram negative rods related to the respiratory tract

Answer 5

Haemophilus Influezae
Legionella Pneumophila

Question 6

Which gram negative rod related to the respiratory tract is primarily found in environmental water sources

Answer 6

Legionella pneumophila (L. pneumophila)

Question 7

mention 3 characteristics of haemophilus species

Answer 7

1. they are small nonmotile Pleomorphic gram-negative bacilli
2. The cells are typically coccobacilli or short rods
3. they are facultative anaerobes (produces energy with or without o2)
4. Species of the genus Haemophilus require protoporphyrin IX (a metabolic intermediate of the hemin biosynthetic pathway)
5. Except for Haemophilus ducreyi, Haemophilus spp. normally inhabit the upper respiratory tract of humans
6. Organism is sensitive to drying and extremes in temperature

Question 8

Mention 3 organisms of the haemophilus species

Answer 8

1. Haemophilus influezae
2. Haemophilus aegyptius
3. Haemophilus ducreyi

Question 9

What is the shape and Gram stain characteristic of Haemophilus influenzae?

Answer 9

Haemophilus influenzae is a small gram-negative rod (coccobacillus)

Question 10

What is significant about the polysaccharide capsule of Haemophilus influenzae?

Answer 10

Haemophilus influenzae has a polysaccharide capsule that plays a crucial role in its virulence and pathogenicity.

Question 11

How many serotypes of Haemophilus influenzae are there, and what are they based on?

Answer 11

There are six serotypes associated with invasive diseases. These serotypes (a, b, c, d, e, or f) are based on differences in the sugar-alcohol phosphate complex within the capsule.

Question 12

What is the composition of the capsule for Haemophilus influenzae?

Answer 12

The capsule is composed of a sugar-alcohol phosphate (polyribitol phosphate) complex

Question 13

what are the common types of invasive diseases caused by h. infuezae

Answer 13

1. Pneumoia
2. Bloodstream infection
3. Meningitis
4. Epiglotittis (swelling of the throat)
5. Cellulitis (skin infection)
6. Infectious arthritis (inflammation of the joint)
   common cause of ear infections in children and bronchitis in adults

Question 14

what is the sigificance/virulence factors of capsule on the body of influezae

Answer 14

capsule is for antiphagocytic (prevents the action of phagocytes)

Question 15

what is the sigificance/virulence factors of igA protease

Answer 15

Cleaves IgA on mucosal surfaces

Question 16

what is the sigificance/virulence factors of Lipid A in H. influezae

Answer 16

Affects ciliated respiratory epithelium cells

Question 17

what is the sigificance/virulence factors of pilli

Answer 17

for attachment

Question 18

How does Haemophilus influenzae enter the body?

Answer 18

It enters by the inhalation of airborne droplets, resulting in either asymptomatic colonization or infections such as otitis media, sinusitis, or pneumonia.

Question 19

What does Haemophilus influenzae degrade and what does this facilitate?

Answer 19

produces IgA protease that degrades secretory IgA, thus facilitating attachment to the respiratory mucosa.

Question 20

Can Haemophilus influenzae spread beyond the respiratory tract? If so, how?

Answer 20

Yes, it can spread beyond the respiratory tract by entering the bloodstream (bacteremia) and spreading to sites including meninges and joints.

Question 21

In which age group do most infections occur with this organism?

Answer 21

Most infections occur in children between 6 months and 5 years with a peak in the age group from 6 months to 1 year.

Question 22

mention of specific conditions caused by Haemophilus influenzae outside of colonization?

Answer 22

conditions mentioned include otitis media, sinusitis, pneumonia, bacteremia, meningitis, and joint infections.

Question 23

mention the clinical manifestations of haemophilus influezae

Answer 23

1. Rapid onset and fever
2. Headache
3. Stiff neck, along with drowsiness
4. Sinusitis and otitis media cause pain i the affected area
5. Opacification of the infected sinus
6. Redness with bulging of the tympanic membrane

Question 24

what is the mode of transmission

Answer 24

1. Droplet infection and discharge from the upper respiratory tract during the infectious period
2. it is infectious as long as the organism is present, even in the absence of nasal discharge
3. It is noninfectios within 24 to 48 hours after the start of effective antibiotics

Question 25

what specimens are preferred for culturing haemophilus influezae

Answer 25

1. CSF 2. Blood 3. Nasopharyngeal specimens *specimens should be cultured as soon as possible and not refregerated)

Question 26

What are the gram staining results for hemophilus influezae for (1)blood and (1)CSF

Answer 26

1. H. influezae is a small non motile gram negative coccobacillus 2. Long thread-like and pleomorphic forms may be seen in c.s.f. (with pus cells), or following culture

Question 27

mention 2 ways how can gram staining for haemophilus influezae be enhanced

Answer 27

1. extending time for safranin to 2 minutes 2. substituting carbol fuschin for safranin

Question 28

explain the morphology of coccobacillus bacteria on microscope

Answer 28

Under the microscope they appear as slightly compressed spheres or ovals

Question 29

What are culture characteristics for haemophilus influezae

Answer 29

1. H. influenzae grows poorly anaerobically. 2. Growth is best achieved in a moist carbon dioxide enriched atmosphere 3. The temperature range of growth is 20–40 ºC with an optimum of 35–37ºC. 4. Media used must contain haemin or other iron-containing porphyrin and nicotinamide adenine dinucleotide (NAD) or its phosphate (NADP ~Factor X used to produce essential respiratory enzymes such as cytochromes, catalase, and peroxidase. ~Factor V is used as an electron carrier in the organism’s oxidation-reduction system.

Question 30

explain the results of culture of haemophilus influezae on chocolate agar

Answer 30

1. After overnight incubation at 35–37 ºC in a moist carbon dioxide atmosphere, capsulated H. influenzae strains produce mucoid colonies, 1.5 mm or more in diameter. 2. Cultures have a distinctive smell 3. Heating blood agar to 75 ºC inactivates serum NADase and releases extra factor V from the red cells. 4. Addition of bacitracin (300 mg/litre) provides a selective medium to recover H. influenzae from sputum(not needed when culturing c.s.f. )

Question 31

biochemical reaction results of haemophilus influezae

Answer 31

1. catalase +ve 2. oxidase +ve 3. reduces nitrite to nitrate 4. ferment glucose and galactose 5. cant ferment sucrose, lactose and mannitol

Question 32

treatments for haemophilus influezae

Answer 32

1. Ceftriaxone 2. Ampicillin 3. use of corticosteroids to fight inflammation