Diphtheria And Anthrax

Front 1

Corynebacteria can be broadly divided into 2 types

Back 1

● Lipophilic corynebacteria

● Non-lipophilic corynebacteria

Front 2

Corynebacterium species can be opportunistic. T/F

Back 2

True.

Front 3

What are lipophilic corynebacteria

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They are corynebacteria that are fastidious and slow growing in media (but addition of lipids to media enhances their growth)

Front 4

Disease cause by C. diphtheriae is called

Back 4

Diphtheria

Front 5

Corynebacteria appearance on gram staining

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● Gram positive

● Appear as curved rods with unparalleled sides and slightly wider ends (Club shape)

● V or L formation

Front 6

Diphtheria toxin is produced by what strain of C. diphtheriae

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Produced by those infected with "lysogenic Beta phage that carries TOX gene". Incorporation of the gene into bacteria genome make it a toxic strain.

Front 7

Molecular weight of diphtheria toxic

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62,000 Da (62kD)

Front 8

Is diphtheria toxin very potent?

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Yes, it is. Very potent and lethal in amounts of 130ng/kg of body weight

Front 9

How does diphtheria toxin act

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It inhibits protein synthesis in eukaryotic cells of body by ribosylating and inactivating Elongation factor 2 (EF2). This leads to cell death

Front 10

Is diphtheria toxin produced in toxic or non-toxic form

Back 10

It is first produced in its non-toxic form. Exposure to trypsin activates it by cleaving it into 2 subunits A and B, both of which are needed for its toxic effects.

Front 11

The initial non-toxic form of diphtheria toxin is made toxic by action of

Back 11

Trypsin

Front 12

Discuss the pathogenesis of diphtheria toxin

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● Diphtheria toxin initially produced in non-toxic form is cleaved by trypsin to 2 subunits A and B, making it toxic

● A is Active subunit while B is Binding subunit

● The B subunit binds to membrane receptors of cells creating channel for A subunit to enter the cell

● A subunit acts on NAD and splits it into Nicotinamide and Adenosine Diphosphoribose (ADPR)

● ADPR ribosylates Elongation factor 2 (EF2) inactivating it, hence preventing polypeptide elongation and protein formation.

● This causes cell death and exudate accumulation that form PSEUDOMEMBRANE in sites of infection (tonsils, Larynx, pharynx)

Front 13

Production of diphtheria exotoxin invitro is dependent on certain factors. Mention them

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● Alkaline pH (7-8)

● Availability of iron

● Oxygen

Front 14

The most important factor needed for production of diphtheria exotoxin invitro is

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Availability of Iron (very key)

Front 15

C. diphtheriae causes 2 types of diseases (diphtheria) in humans, mention them.

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● Respiratory diphtheria

● Cutaneous diphtheria

Front 16

The type of vaccine against diphtheria is a

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Toxoid vaccine

Front 17

The ONLY natural hosts of C. diphtheriae are

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Humans

Front 18

C. diphtheriae is spread by

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● Respiratory droplets (as seen in sketchy)

● Hand to mouth contact

Front 19

The common sites of infection of C. diphtheriae are

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● Pharynx

● Tonsils

Front 20

Does diphtheria toxin affect the heart?

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Yes, it causes cardiotoxic effects like arrhythmias, heart block, myocarditis.

Front 21

Cutaneous diphtheria is also known as ? Why is it called that

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● Desert sores

● Because it causes non healing ulcers with dirty grey appearance (like the appearance of pseudomembrane)

Front 22

C. diphtheriae is highly Pleomorphic. T/F

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True (despite being described as club shaped, they are pleomorphic)

Front 23

The metachromatic granules of C. diphtheriae are known as

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Babès-Ernst granules (composed of polymerized polyphosphates)

Front 24

Based on aerobic and anaerobic classification, what type of organism is C. diphtheriae

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Facultative anaerobe (though it grows best at aerobic state like most facultative anaerobes)

Front 25

Growth media of C. diphtheriae are? What optimum temperature does it grow

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● Growth media : Loeffler's media, Pai media, Cystine-Tellurite blood media

● Optimum temperature : 37°C

Front 26

Test to differentiate toxic and non-toxic strain of C. diphtheriae is called

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Elek test

Front 27

Describe C. diphtheriae based on

● Catalase test

● Nitrate test

● Lactose fermenter

● Motility

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● Catalase positive

● Converts nitrate to nitrite

● Lactose fermenter (pink on MacConkey agar)

● Non-motile

It has the same general features as STAPH and STREP.

Front 28

Anthrax is a disease commonly found in

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Cattle, goat, sheep

Front 29

Anthrax is a also known as

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Wool sorter's disease or Rag picker's disease

Front 30

The 3 routes of exposure to B. anthracis are

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● Cutaneous

● Inhalational

● Ingestion