pg 1-6 C. diphtheriae

CORYNEBACTERIUM DIPHTHERIAE

NM, NS, NE

CORYNEBACTERIUM DIPHTHERIAE

Common name: kleb loeffler's bacillus

CORYNEBACTERIUM DIPHTHERIAE

Catalase (+)

CORYNEBACTERIUM DIPHTHERIAE

Urease (-)

CORYNEBACTERIUM DIPHTHERIAE

Dnase (+)

CORYNEBACTERIUM DIPHTHERIAE

Straight or slightly curved with one end that is typically swollen

CORYNEBACTERIUM DIPHTHERIAE

Ferments dextrose & maltose

CORYNEBACTERIUM DIPHTHERIAE

Highly pleomorphic, club shaped, bard shaped

CORYNEBACTERIUM DIPHTHERIAE

"coryne" means "club" in greek

CORYNEBACTERIUM DIPHTHERIAE

Metachromatic granules babes ernst granules made of polyphosphates

chinese letter or picket fence, palisade

Gram stain reaction: forms X,V, Y and L formation resembles "_

Serum, Cysteine, Potassium tellurite

Enrichment medium recommended:

CORYNEBACTERIUM DIPHTHERIAE

Can be found as normal flora

mycobacterium & nocardia

CORYNEBACTERIUM DIPHTHERIAE

Closely related to

Media of choice

Sheep's blood/BAP

48

Incubated at 35 to 37 C w/ 5-10% CO2 | _ hours

lipophilic corynebacterium

If mabagal tumubo = 3 or more days: _

Diphtheria toxin

Virulence factor: _ - exotoxin

Fragment B

Fragment A

Virulence factor fragments: - entry of fragment A in cytoplasm, _ - responsible for cytotoxicity

Respiratory droplets, Direct contact to cutaneous, Hand to mouth contact

Mode of transmission:

CORYNEBACTERIUM DIPHTHERIAE

Incubation period: 2-5 days

CORYNEBACTERIUM DIPHTHERIAE

Humans are the only natural host

Tonsils, Pharynx

Most common site of infection:

beta

BAP: narrow _ hemolysis

CTBA (cystine tellurite blood agar)

gray to black colonies

Tindales medium

black colonies w/ brown halo

Loeffler's serum

poached egg colonies

Loeffler's serum slant and PAI's coagulated egg serum

enhances pleomorphism & granule formation

penicillin, erythromycin

Drug of choice:

ELISA

another test for toxigenicity

Vero cell cytotoxicity assay

gold standard

Diphtheria

CORYNEBACTERIUM DIPHTHERIAE CLINICAL INFECTIONS

acute communicable disease manifested by local infection of upper RT and systemic effects (heart and peripheral nerves)

Respiratory forms and Cutaneous form

CORYNEBACTERIUM DIPHTHERIAE CLINICAL INFECTIONS

Two forms:

Respiratory forms

CORYNEBACTERIUM DIPHTHERIAE CLINICAL INFECTIONS

Pharyngitis w/ exudative membrane that covers tonsils, uvula, palates

Respiratory forms

CORYNEBACTERIUM DIPHTHERIAE CLINICAL INFECTIONS

Acquired through droplet infection or hand to mouth contact

Respiratory forms

Signs and symptoms include low grade fever, thick nasal discharge & cough

Respiratory forms

CORYNEBACTERIUM DIPHTHERIAE CLINICAL INFECTIONS

Gray to white pseudomembranous formation: once developed will cause the

patient to show the unique

symptom which is bull's neck

appearance/swollen neck

Respiratory forms

Death is often result of cardiac failure

Cutaneous form

CORYNEBACTERIUM DIPHTHERIAE CLINICAL INFECTIONS

slow healing ulcers and membrane formation

Cutaneous form

CORYNEBACTERIUM DIPHTHERIAE CLINICAL INFECTIONS

Due to ulcerative toxin

Cutaneous form

MOT includes respiratory droplets, direct contact w/ cutaneous lesions

Cutaneous form

Diagnostic feature is pseudomembrane diphtheria

Toxigenic

capable of producing exotoxin

Mitis, Intermedius, Gravis, Belfanti

Non toxigenic: biotypes (based on CHO fermentation and hemolysis)

Enumerate the 4

Mitis

convex, fried egg colonies, black colonies w/ gray periphery

Intermedius

small, dry gray or black colony on CTA

Gravis

daisy head colonies; large gray colonies —

corynebacterium diphtheriae

var gravis

Belfanti

does not produce any diphtherial toxin

Nasopharyngeal, Throat swabs, Skin/wound lesions

LABORATORY DIAGNOSIS OF CORYNEBACTERIUM DIPHTHERIAE

Specimen:

Gram stain, LAMB, Neisser's, Albert's, and Ljubinsky

Stained smears include

Culture

primary inoculation of throat swab to loeffler serum slant and overnight incubation and subculture of any growth to cysteine-tellurite blood agar (CTBA)

SCHICK'S TEST

Skin test for C. diphtheriae

SCHICK'S TEST

Test arm receives 0.1 ml diphtheria toxin

SCHICK'S TEST

Control arm receives 0.1 ml diphtheria toxin

SCHICK'S TEST

(+) result: Redness & swelling after 3 days, persist to the 6th day, and fades gradually

DPT - diphtheria pertussis tetanus

SCHICK'S TEST

(-) result/no reaction: Indicates immunity through immunization (_)

SCHICK'S TEST

Control reaction time: 24-48 hours

TOXIGENICITY

is a virulence test

In vivo toxigenicity

animal inoculation (Roemer's test) involves guinea pig

In vitro toxigenicity

modified elixir tests —

immunodiffusion test —

definitive test

In vitro toxigenicity

Incubate in 24-48 hours

In vitro toxigenicity

(+) result is precipitin line at 45 degree angle

amie's

Transport medium:

CYSTINE TELLURITE BLOOD AGAR

Colonies appear black/gray

CYSTINE TELLURITE BLOOD AGAR

Modification of tindales medium

CYSTINE TELLURITE BLOOD AGAR

Contains sheep rbcs, bovine serum, cystine & potassium tellurite

CYSTINE TELLURITE BLOOD AGAR

Gun metal colonies

MODIFIED TINSDALE AGAR

Colonies are black w/ brown halos

LOEFFLER'S MEDIUM

May stimulate the growth of C. diphtheriae and the production of metachromatic granules

REVERSE CAMP TEST

Incubation period at 37C for 24-48 hours in aerobic conditions

Tween 80 test

Useful preliminary identification of a

certain coryneform bacteria, such as c.

jeikeium and c. urealyticum

Thioglycollate broth & Brain-Heart

infusion

OTHER ROUTINE BLOOD CULTURE &

NUTRIENT BROTH USED FOR

CORYNEBACTERIUM SPP

If broths are infused w/ rabbit serum,

lipophilic coryneform bacteria will

enhance growth

OTHER ROUTINE BLOOD CULTURE &

NUTRIENT BROTH USED FOR

CORYNEBACTERIUM SPP