Corynebacterium Diphtheriae: Morphology, Pathogenicity, and Clinical Aspects, Study notes of Medical Microbiology

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CORYNEBACTERIUM

-^ MORPHOLOGY^ ·^ Gram^ +vo^ bacilli

· non 

sporing

non motile

· show club^ shaped swelling · (^) also known as (^) KLB Klebs-Loeffler bacillus · posses (^) polymetaphosphate granules

• (^) serve as energy also called^ storage

Babes Ernst

granules or (^) metachromatic granules · Arranged in pairs ,^ palisades^ (parallel vows)^ or small^

groups

. · show Chinese^ letter^

arrangement

or uniform arrangment PATHOGENICITY · virulent (^) strains of (^) dipthesia bacilli produce a (^) very powerful exotoxin It consists^ of^2 fragments. & ↓ * A B · it is (^) toxic enzyme (^) it is responsible for (^) binding the (^) toxin (^) to (^) cells · when released is (^) inactive as active site is masked (^) on fragment A · Activation happens due^ to

proteases present^

in infected tissues · The incubation period is (^) usually 3- days · site of (^) infection may be-

i) pharyngeal -^ most common

2. nasal

3) Laryngeal

n) Otitic

9. Genital^

• vaginal >^

vulval

6. (^) Conjunctival

cutaneous They (^) may be^ classified^ based^ on^ their^ severity Malignant or (^) hypertoric - > Swere toxemia with marked adenitis^ (bulk^ neck) · death (^) due to circulatory failure · High incedence^ of

paralytic sequelae^

in those who recover

Septic which^ leads (^) to ~ ulcers

cellulitis

even gangrene

Gram stair · granules are more gram

the so they

appear slightly swollen - >^ club shaped Loeffler's (^) methylene blue · granules take^ up (^) bluish-purple color^ hence called (^) metachromatic

granules

· bacilli not^ demonstrated

properly

Leishman stain^ ·^ done^ to^ rule out^ vincent's^ spirochets a fusiform

bacilli

• (^) Immunofluorescere Biochemical Reactions- Hiss scrum' ferments glucose

• galactose

with (^) acid but maltose no gas dextrin doesn't ferment - lactose mannitol sucrose

emonstration

of

Toit

• ~

In vivo test^

• no (^) longer done Invitro test · (^) in animals (^) on agar plate/tissue^ culture

I ↓

-^ I ↓ ↓ (^) * Elek's^ get Tissue Subcutaneous Intravenous (^) ppt +est^ ulture ↓

0.^ 8 m) of emulsion 0. I met is

other with^300 units (^) (previous day) change injected in^2 pigs injected . after (^) culturing on loeffless (^) dope one is^ injected with^ so^ units (^) (4 his after s b after (^) 48-72 his^ necrosis^ can^ be^ seen^ at site of^ injection one (^) pig

other is

injected

with

is (^) unprotected 500 unit^ of^ antitoxin ↓ will die^ after^ 2- days as

strain is^ virulent

Elek's get precipitation test · (^) A filter paper impregnated^ with diptheria antitoxin (^) is placed on horse (^) scrum agar platz · After agar solidites (^) , test strain is streaked (^) at (^) right

angle

to filter^ paper strip tre and-ve control (^) are put up . plate

is incubated at 372 for 24-48 h

· Toxin produced diffuses^ in agar and forms^ a (^) precipitation line ↑

if present not^ present

Strain toxic non-toxic the control^ < & Test strain (^) showing ↓ &^ toxigenicity

filter^ paper soaked^ with diptheria antitoxin poline

• &Y y^ & -ve^ control Tissue culture method · strains are incorporated in^ agar overlay^

of cell culture

monolayers · The (^) toxin produced by^ organism diffuses (^) into the cells below ? causes (^) lysis of^ cells. PROPHYLAXIS

Active Immunisation-^ done

by toxoided form^ of (^) diptheria toxin. I ↓ * formal (^) toxoid Adsorbed^ toxoid · (fluid toxoid) (^) ·

prepared by purifying toxoid^ adsorbed

· prepared by incubating^ toxin with^ onto aluminium phosphate formalin · more immunogenic . DPT vaccine - > diphtheria (^) perfusis tetanus young

children +3^ doses^ at^ internal^ of a month^ (4 weeks)

Booster Rose 1-1"^ up

• (^) DPT 2

by

DT 3

10 ye

TT