Gram-Negative Rods Related to the Respiratory Tract

Question 1

WHAT ARE THE Gram-Negative Rods Related to the Respiratory Tract

Answer 1

Genus - Haemophilus
Genus – Bordetella
Genus – Legionella
Genus – Acinetobacter

Question 2

where can we find the RESPIRATORY TRACT bacteria

Answer 2

Haemophilus influenzae and Bordetella pertussis are found only in
humans, whereas L. pneumophila is found primarily in environmental
water sources. Acinetobacter baumannii is found in environmental water
sources but also colonizes the skin and upper respiratory tract

Question 3

TALK ABOUT -HAEMOPHILUS INFLUENZA

Answer 3

it is a gram negative rod , it is facilitative anaerobe , it has a polysaccharide capsule
it is one of the three important encapsulated pyogenes

it has 6 different antigens ( abcdef ) on the capsule but the most important is Antigen B

the capsule allow the bacteria to resist phagocytosis

Question 4

What are the diseases caused by haemophiles influenza

Answer 4

the leading cause of meningitis in young children,
cause of upper respiratory tract infection
causes pneumonia in adults

Question 5

what are the Pathogenesis & Epidemiology Haemophilus influenza

Answer 5

it infects only humans It enters the body by the inhalation of airborne droplets into the respiratory tract

The organism produces an IgA protease that degrades secretory IgA, thus
facilitating attachment to the respiratory mucosa

it causes meningitis

Pathogenesis of H. influenza involves its antiphagocytic capsule and endotoxin;
no exotoxin is produced.

Question 6

laboratory diagnosis for haemophiles influenza

Answer 6

it depends on the isolation of the organism on chocolate agar 
and add two important growth factors 
which are   ( factor X (a heme compound) and factor V (NAD). ) 

it will grow with the presence of both factors

Question 7

what are the treatment and prevention of the Hemophilus influenza ?

Answer 7

ceftriaxone
upper respiratory tract infections are treated with either amoxicillin-clavulanate

The vaccine contains the capsular polysaccharide of H. influenzae
type b conjugated to diphtheria toxoid or other carrier protein.
Depending on the carrier protein, it is given some time between the
ages of 2 and 15 months.

• Conjugated vaccine is much more effective in young children

Question 8

what is conjugated vaccine

Answer 8

A conjugate vaccine is a type of vaccine which combines a weak antigen with a strong antigen as a carrier so that the immune system has a stronger response to the weak antigen

Question 9

TALK ABOUT BORDTELLA

Answer 9

species - Bordetella pertussis
it is a gram-negative rod, it is aerobic and motile
Disease
• Bordetella pertussis causes whooping cough (pertussis) One remarkable
feature of the disease is a great increase in lymphocytes

Question 10

what is Pathogenesis & Epidemiology Bordetella pertussis,

Answer 10

Bordetella is only for humans caused by air-borne droplets

The organisms attach to the ciliated epithelium of the upper respiratory
tract but do not invade the underlying tissue.

Decreased cilia activity and subsequent death of the ciliated epithelial cells are important aspects of pathogenesis

Question 11

what are the virulence factors for Bordetella ?

Answer 11

1 pili called filamentous hemagglutinin.

2 Pertussis toxin stimulates adenylate cyclase by catalyzing the addition
of adenosine diphosphate ribose—a process called ADP-ribosylation—to
the inhibitory subunit of the G protein complex (Gi protein).
This results in edema of the respiratory mucosa that contributes to the severe cough of pertussis .

(3) The organisms also synthesize and export adenylate cyclase
(4) Tracheal cytotoxin

Question 12

laboratory diagnoses of Bordetella pertussis ?

Answer 12

Bordetella pertussis can be isolated from nasopharyngeal swabs
taken during the paroxysmal stage. ‘

Bordet Gengou Blood Agar

Question 13

Difference Between Agglutination and Precipitation

Answer 13

• Both agglutination and precipitation reactions are the result of interaction between antibody and antigen.

Question 14

What is Agglutination?

Answer 14

It is the antigen-antibody reaction where the antibody reacts with the insoluble antigen to form agglutin

Question 15

What is Precipitation?

Answer 15

it is the antigen-antibody reaction where the antibody reacts with the soluble antigen to form precipitin.

Question 16

treatment and prevention of Bordetella pertussis

Answer 16

Azithromycin

There are two types of vaccines: an acellular vaccine containing
purified proteins from the organism and a killed vaccine containing
inactivated B. pertussis organisms.

The acellular vaccine has fewer side effects than the killed vaccine but
has a shorter duration of immunity

Boostrix contains diphtheria and tetanus toxoids
also. Another vaccine called Adacel also contains diphtheria and
tetanus toxoid.

Question 17

TALK ABOUT GENUS LEGIONELLA

Answer 17

It is gram-negative rod , non-capsulated, non spore-forming

L. pneumophila is the primary human pathogen and is the causative agent o legionellosis.
L. pneumophila is a facultative intracellular parasite

it stain weakly with the standard Gram stain

Question 18

what is the disease for legionella

Answer 18

Legionella pneumophila

Question 19

why During the 1976 outbreak, initial attempts to grow the organisms on
ordinary culture media failed

Answer 19

This is because the organism requires a high concentration of
iron and cysteine.

Question 20

Laboratory diagnosis for Legionella

Answer 20

No growth on standard Sheep Blood Agar
- Silver stain
- Grown on Buffered charcoal yeast extract agar BCYE 
- Growth conditions: 350C ; 3-7 days
Rapid identification:
1. Immunofluorescent microscopy
2. PCR

Question 21

what is the Pathogenesis & Epidemiology of Legionella

Answer 21

in environmental water sources
Legionellae can replicate to large numbers in free-living amebas in these
water sources

The portal of entry is the respiratory tract, and pathologic changes occur
primarily in the lung.

The major virulence factor of the organism is lipopolysaccharide
(endotoxin).

• In humans, L. pneumophila invades and replicates inside macrophages

Question 22

how does legionella cause disease

Answer 22

• L. pneumophila use a type IV-B secretion system (T4SS) known as Dot/Icm to
inject effector proteins into the host. These effectors are involved in increasing
the bacteria’s ability to survive inside the host cell.

• Legionella infecting alveolar lung macrophages

, person-to-person spread does not occur

Question 23

what are the Effector systems ?

Answer 23

Effector systems allow for the interaction between microbes and larger
organisms. The effector systems are used as a toxin delivery method by
many human pathogens such as, Helicobacter pylori (stomach
ulcers), Bordetella pertussis (whooping cough), and Legionella
pneumophila (Legionnaires’ disease)

Question 24

treatment and prevention of legionella

Answer 24

Azithromycin or erythromycin

reducing cigarette and alcohol consumption,
eliminating aerosols from water sources,

there is no vaccine

Question 25

TALK ABOUT Acinetobacter

Answer 25

IT is a genus of gram negative rod
it is oxidative negative and it has twitching motality

they are found in soil and water but they colonize in the upper respiratory tract

Question 26

what are the diseases that cause Acinetobacter

Answer 26

• Pneumonia and urinary tract infections
it can cause various other infections, including skin and wound infections,

i is the greatest cause bacteremia, urinary tract infections (UTIs), secondary meningitis, infective endocarditis, and wound and burn infections.

Question 27

Laboratory diagnosis and pathology for Acinetobacter

Answer 27

Laboratory diagnosis is made by culturing the organism.

• Acinetobacter baumannii is remarkably antibiotic resistant, and some
isolates are resistant to all known antibiotics