Whooping Cough, Bronchtits, Bronchiolitis &TB Flashcards

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1
Q

Mention virulence factors of B.pertussis

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

Function of pili

A

Attachment of organism to cilia of the epithelial cells

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3
Q

Function of pertussis toxin

A

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

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4
Q

Function of adenylate cyclase

A

Inhibit bactericidal activity

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5
Q

Function of tracheal cytotoxin

A

Damages ciliated cells of respiratory tract

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6
Q

Site of B.pertussis colonization

A

Tracheobronchioles

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7
Q

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

A

Intefere with ciliary action preventing expulsion of mucus.

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8
Q

Pathogenesis of coughing in pertussis infection

A

Liberation of different toxina & irritation of surface epithelia

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9
Q

Obstruction of terminal bronchioles in whooping cough leads to

A

Diminished oxygenation & convulsions

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10
Q

Incubation period of whooping cough

A

2 weeks

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11
Q

Stages and C/P of whooping cough

A
  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
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12
Q

Complications of whooping cough

A

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

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13
Q

Mention result of CBC & preferred specimen in whooping cough

A

Lymphocytosis

Nasopharyngeal wash

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14
Q

Medium used for isolation of B.pertussis & colonial morphology

A

Charcoal blood agar, Bordet-Gengou medium

Mercury drops

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15
Q

Complications of DPT vaccine and maximum age of administration.

A

Convulsion & encephalopathy

Under age of 7 years

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16
Q

Contents of DTaP vaccine related to B.pertussis

A

Endotoxin, toxoid, filamentous hemagglutinin & fimbria

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17
Q

Age if administration of Tdap vaccine

A

Age 11 and adults

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18
Q

GR: Smoking predisposes to bronchitis

A

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

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19
Q

Mention special sign of physical examination of bronchitis

A

Expiratory wheezes

20
Q

Mention the most common and second causative agent of bronchiolitis

A

1st Respiratory syncytial virus

2nd Human metapneumovirus

21
Q

Complications of bronchiolitis

A

Hypoxia, apnea & respiratory failure.

22
Q

Mention diseases caused by respiratory syncytial virus in different ages

A

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

23
Q

Target age of bronchiolitis

A

Under 2 yrs

24
Q

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

A

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.

25
Q

Ab to ….. provide immunity against RSV

A

F protein

26
Q

Preferred laboratory methods of diagnosis of RSV/HMPV

A

Antigen detection by ELISA

Nucleic acid detection by RT-PCR

27
Q

The waxy lipid layer of mycobacterium is responsible for:

A
  • Acid fastness
  • Protection frim lysis once they are phagocytosed
  • Capability of intracellular growth
28
Q

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

A

Cord factor (trehalose dimycolate)

29
Q

……. Allows M.T. to grow intracellularly

A

Mycolic acid

30
Q

M.T. Is stained by

A

Ziehl-Neelsen & Kinyoun methods

Fluorescence auramine stain

31
Q

Describe the main virulence factor of M.T.

A

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

32
Q

MOT of M.T.

A

Airbone droplet nuclei

Contaminated dust particles

33
Q

Mention the modes of T.B. infection

A

Symptomatic disease
Latent infection
Reactivation of latent infection

34
Q

Mention features of symptomatic disease of T.B.

A
  • Night fever, sweats & loss of appetite & weight

- Cough & sputum may be blood stained

35
Q

GR: Mycobacteria in latent infection are metabolically inactive

A

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

36
Q

Mention complications of reactivation of latent T.B.

A

Tuberculous meningitis, osteomyelitis & Pott’s disease

37
Q

Specimens of choice in active pulmonary TB

A

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

38
Q

Mention the egg based medium of MT

A

Lowenstein-Jensen medium

39
Q

Mention situations in which diagnosis of latent TB is recommended

A

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

40
Q

Mention the antigen injected & how to interpret TST

A

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

41
Q

Mention false positive result conditions of TST

A

Atypical mycobacteria, BCG vaccination

42
Q

Mention false negative result conditions of TST

A

Impaired cellular response / BCG vaccination

43
Q

When is IGRA more favourable than TST

A

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

44
Q

Advatages of IGRA

A

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

45
Q

Disadvantages of IGRA

A

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

46
Q

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

A

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