Whooping Cough, Bronchtits, Bronchiolitis &TB

Question 1

Mention virulence factors of B.pertussis

Answer 1

1. Pilli
2. Pertussis toxin
3. Adenylate cyclase
4. Tracheal cytotoxin
5. Capsule
6. Endotoxin

Question 2

Function of pili

Answer 2

Attachment of organism to cilia of the epithelial cells

Question 3

Function of pertussis toxin

Answer 3

Stimulate adenylate cyclase leading to incraesed cAMP, respiratory edema & severe cough.
Prevent entry of lymphocytes to lymphoid tissue causing lymphocytosis

Question 4

Function of adenylate cyclase

Answer 4

Inhibit bactericidal activity

Question 5

Function of tracheal cytotoxin

Answer 5

Damages ciliated cells of respiratory tract

Question 6

Site of B.pertussis colonization

Answer 6

Tracheobronchioles

Question 7

What is the result of adhesion & multiplication of organism on ciliated epithelial surface?

Answer 7

Intefere with ciliary action preventing expulsion of mucus.

Question 8

Pathogenesis of coughing in pertussis infection

Answer 8

Liberation of different toxina & irritation of surface epithelia

Question 9

Obstruction of terminal bronchioles in whooping cough leads to

Answer 9

Diminished oxygenation & convulsions

Question 10

Incubation period of whooping cough

Answer 10

2 weeks

Question 11

Stages and C/P of whooping cough

Answer 11

1. Catarrhal stage: mild coughing and sneezing, highly infectious.
2. Paroxysmal stage: severe successive attacks of cough with charecteristic whoop
3. Convalescent stage: chronic cough

Question 12

Complications of whooping cough

Answer 12

Cyanosis, convuslions, subconjuctival hemorrhage, vomiting & secondary bacterial infection.

Question 13

Mention result of CBC & preferred specimen in whooping cough

Answer 13

Lymphocytosis

Nasopharyngeal wash

Question 14

Medium used for isolation of B.pertussis & colonial morphology

Answer 14

Charcoal blood agar, Bordet-Gengou medium

Mercury drops

Question 15

Complications of DPT vaccine and maximum age of administration.

Answer 15

Convulsion & encephalopathy

Under age of 7 years

Question 16

Contents of DTaP vaccine related to B.pertussis

Answer 16

Endotoxin, toxoid, filamentous hemagglutinin & fimbria

Question 17

Age if administration of Tdap vaccine

Answer 17

Age 11 and adults

Question 18

GR: Smoking predisposes to bronchitis

Answer 18

By damaging the cilia in the bronchi leading to inability to clear mucus from RT.

Question 19

Mention special sign of physical examination of bronchitis

Answer 19

Expiratory wheezes

Question 20

Mention the most common and second causative agent of bronchiolitis

Answer 20

1st Respiratory syncytial virus

2nd Human metapneumovirus

Question 21

Complications of bronchiolitis

Answer 21

Hypoxia, apnea & respiratory failure.

Question 22

Mention diseases caused by respiratory syncytial virus in different ages

Answer 22

Infants, bronchiolitis & pneumonia
Young children: otitis media
Adults: common cold
Elderly/immunosuppressed, pneumonia

Question 23

Target age of bronchiolitis

Answer 23

Under 2 yrs

Question 24

Mention virulence factors of respiratory syncytial virus & their role in pathogenesis.

Answer 24

G protein, attaches to cell to be infected

F protein, fusion of viral envelope to cell membrane, also causes cell fusion leading to syncytia formation.

Question 25

Ab to ..... provide immunity against RSV

Answer 25

F protein

Question 26

Preferred laboratory methods of diagnosis of RSV/HMPV

Answer 26

Antigen detection by ELISA | Nucleic acid detection by RT-PCR

Question 27

The waxy lipid layer of mycobacterium is responsible for:

Answer 27

- Acid fastness - Protection frim lysis once they are phagocytosed - Capability of intracellular growth

Question 28

Teh virulence factor allow M.T. to grow in parallel groups

Answer 28

Cord factor (trehalose dimycolate)

Question 29

……. Allows M.T. to grow intracellularly

Answer 29

Mycolic acid

Question 30

M.T. Is stained by

Answer 30

Ziehl-Neelsen & Kinyoun methods | Fluorescence auramine stain

Question 31

Describe the main virulence factor of M.T.

Answer 31

The organism is non-toxigenic. It produces disease by its ability to survive & multiply within macrophages due to presence of cord factor.

Question 32

MOT of M.T.

Answer 32

Airbone droplet nuclei | Contaminated dust particles

Question 33

Mention the modes of T.B. infection

Answer 33

Symptomatic disease Latent infection Reactivation of latent infection

Question 34

Mention features of symptomatic disease of T.B.

Answer 34

- Night fever, sweats & loss of appetite & weight | - Cough & sputum may be blood stained

Question 35

GR: Mycobacteria in latent infection are metabolically inactive

Answer 35

Due to low pressure and anoxic environment but tehy are viable and can be released later in life.

Question 36

Mention complications of reactivation of latent T.B.

Answer 36

Tuberculous meningitis, osteomyelitis & Pott’s disease

Question 37

Specimens of choice in active pulmonary TB

Answer 37

Sputum (3 successive morning amples) Bronchial washings Pleural fluid Gastric aspirate

Question 38

Mention the egg based medium of MT

Answer 38

Lowenstein-Jensen medium

Question 39

Mention situations in which diagnosis of latent TB is recommended

Answer 39

HIV infection Recent contact wiyh an infectious pateint or immigrant from a country with high TB burden Immunocompromised Imprisoned, homeless, drug users

Question 40

Mention the antigen injected & how to interpret TST

Answer 40

Purified protein derivative INT: Equal/more than 5 mm in immunocompromised patients Equal/more than 10 those at high risk with no medical conditions favouring reactivation as drug abusers, microbiology workers, homeless, children less than 4 yrs exposed to adults in high risk groups Equal/more than 15 no risk factors for TB

Question 41

Mention false positive result conditions of TST

Answer 41

Atypical mycobacteria, BCG vaccination

Question 42

Mention false negative result conditions of TST

Answer 42

Impaired cellular response / BCG vaccination

Question 43

When is IGRA more favourable than TST

Answer 43

BCG vaccination, children less than 5 years and in cases with poor rate of return for reading TST result

Question 44

Advatages of IGRA

Answer 44

Requires a single patient visit, results in 24 hrs, BCG vaccination causes no false +ve

Question 45

Disadvantages of IGRA

Answer 45

Expensive, does not differentiate latent & active, should be processed withinn 8-16 hours when WBCs are still viable.

Question 46

Mention type, route of administration, age & imp of BCG vaccine

Answer 46

Live attenuated ID First 3 months if life Limited protection but reduces morbidity & mortality in children kess than 5 yrs